Process for separating multicomponent gas mixtures without off-gas

Abstract

It relates to a vacuum temperature pressure swing adsorption (VTPSA) process for the recovery of individual gas components from a multicomponent gas mixture M without gas emissions into the atmosphere, wherein the multicomponent gas mixture M comprises at least three gas components XA, XB, and XC, and the process comprises at least one cycle of steps carried out with a number of adsorption columns nC which is either nx-1, or alternatively a multiple of nx-1, wherein nx is the number of the gas components of the multicomponent gas mixture M. The process is particularly suitable for the recovery of refrigerant gases and allows obtaining each of the separated gases in high purity (> 95%).

Description

[0001] Process for separating multicomponent gas mixtures without off-gas

[0002] This application claims the priority of the European Patent Application EP23383110.6 filed on 31.10.2023.

[0003] Technical Field

[0004] The present invention relates to process for separating multicomponent gas mixtures, particularly refrigerant gas mixtures, of three or more components and obtaining all of them in high purity without emissions of off-gas.

[0005] Background Art

[0006] Global refrigerant usage encompasses a growing number of applications that are critical to modern society. By the 1930s, Thomas Midgely, Albert L. Henne, and Robert R. McNary had discovered fluorocarbon refrigerants, leading to the widespread use of chlorofluorocarbon (CFG) and hydrochlorofluorocarbon (HCFC) refrigerants (second- generation refrigerants).

[0007] However, by the mid-1980s, CFCs were linked to the depletion of the Earth’s ozone layer. In 1987, the Montreal Protocol was signed limiting the production of ozone depleting substances such as CFCs. In 1992, the Copenhagen amendment to the Montreal protocol called for the phaseout of HCFCs by the year 2030. The phaseout of CFCs and HCFCs led to the development of hydrofluorocarbon (HFC) refrigerants which have zero ozone depletion potential (ODP). HFCs are considered third-generation refrigerants and have been in production and use for the past thirty years.

[0008] Today, concerns over the global warming potential (GWP) of HFCs has become an issue. In fact, some HFCs contribute thousands of times more to global warming than carbon dioxide on an equivalent mass basis. In the global effort to mitigate climate change, a series of legislative actions have been taken that affects HFC use and production.

[0009] The Kyoto Protocol in 2005, F-gas regulations by the European Union in 2014, the Kigali Amendment to the Montreal Protocol in 2016, and the American Innovation and Manufacturing (AIM) act in 2020 are among the most recent actions taken to phase out and limit the use of HFCs.

[0010] As a result of the phaseout of HFCs, the transition to fourth-generation refrigerants is currently underway. As the air-conditioning and refrigeration (RAC) industry transitions to hydrofluoroolefins (HFOs), something must be done with the estimated 2800 ktons of refrigerant currently in use globally. Opposed to venting or incinerating these high GWP refrigerants, a more preferable route would be to reclaim, separate, and recycle them.

[0011] Recycling is considered an important and timely approach to minimize environmental release, production and as an alternative way to meet future demand prior to disposal. Therefore, the design of scalable and industrially applicable processes to recycle these refrigerant gases is considered a highly important priority for the industry. However, this process is becoming more difficult due to the similar thermophysical properties of HFC mixture components and the azeotropic nature of many of these HFC blends.

[0012] The most widely used method for the recovery of fluorinated compounds used on a large scale is cryogenic separation; that is, liquefaction followed by distillation. However, in many cases, the purity of the separated fluorinated compounds does not meet industry applicable standards after distillation. This is because during the distillation process most refrigerant mixtures produce azeotropic mixtures that are extremely difficult to separate by means of cryogenic separation. Cryogenic distillation can perform some separations but is highly energy intensive and not effective at separating azeotropic compositions. However, the use of solid sorbents has been reported in the patent literature for separating azeotropic refrigerant mixtures. The use of sorbents for the separation of HFC refrigerant mixtures based on differences in molecular size and interactions is a promising, less energy-intensive alternative to conventional distillation processes.

[0013] An extensive literature search has been performed for fluorocarbon sorption on porous materials. Literature and patent data have been found on the sorption of fluorocarbons including CFCs, chlorofluoroolefins (CFOs), HCFCs, hydrochlorofluoroolefins (HCFOs), HFCs, HFOs, perfluorocarbons (PFCs), and perfluoroolefins (PFOs) in porous materials such as zeolites, activated carbons, and metal organic frameworks (MOFs). Nevertheless, in the literature there is not published an efficient and viable industrial process for the separation, but just some separation lab tests. The development of these processes is one of the great socioeconomic and environmental challenges of our century and represents a priority not only for the European Union (EU) but also globally.

[0014] Adsorption-based gas separation is a well-established technology that is considered a more energy-efficient method. However, in the processes developed in the current publications by Pressure Swing Adsorption (PSA), Temperature Swing Adsorption (TSA), Vacuum Swing Adsorption (VPSA) and a combination of these only one of the components of the mixture with a high purity by venting or eliminating the remaining gas stream (off-gas) with low purity. Therefore, there is still the need to provide methods for separating and recycling refrigerant multicomponent gas mixtures which overcome the problems of the prior art and can be used in an industrial scale.

[0015] Summary of Invention

[0016] The inventors have developed an adsorption-desorption process by temperature and pressure changes which allows the separation of gas molecules from mixtures of three or more gas components, particularly refrigerant gases, and obtaining each of the separated gases in high purity (> 95%).

[0017] The adsorption process of the invention is based on a modification of the Skarstrom cycle. Typically the Skarstrom cycle is applied to separations of two-component mixtures. The component to be purified or objective is recovered while the fraction enriched with the unwanted product and a fraction of the target component is discarded. By contrast the adsorption process of the invention is completely hermetic, without emissions of off-gas into the atmosphere.

[0018] The process is reproducible, stable, and capable of meeting the technical and functional requirements to be used in industrial processes such as commercial refrigeration processes. The process can be automatically controlled to allow obtaining a product that meets the desired technical specifications where the emission and / or destruction of fluorocarbons and natural refrigerants is eliminated, improving the added value of a waste, and thus contributing to a reduction in environmental impact.

[0019] Altogether, the invention provides an industrial effective process for recovery of gas components used on a large scale, particularly refrigerant gases, for its subsequent recycling, thus minimizing the emission of this type of gases into the environment and also avoiding their production.

[0020] Therefore, an aspect of the present invention relates to a vacuum temperature pressure swing adsorption (VTPSA) process for the recovery of individual gas components from a multicomponent gas mixture M without gas emissions into the atmosphere, wherein:

[0021] - the multicomponent gas mixture M comprises at least three gas components XA, XB, and Xc, and

[0022] - the process is carried out with a number of adsorption columns nc which is either nx-1 , or alternatively a multiple of nx-1 , wherein nxis the number of the gas components of the multicomponent gas mixture M, and comprises at least one cycle of the following steps: a) feeding a multicomponent gas mixture M to an adsorption column (1) at a suitable working pressure HP1 which is in the range from 100 to 6000 kPa, wherein the adsorption column (1) comprises an adsorbent that selectively retains a first gas component Xc, while letting out a light current (LC1) which contains components XA and XB and is depleted in component Xc; b) feeding the light current obtained in step a) to an adsorption column (A) at a suitable working pressure HP2 which is in the range from 100 to 6000 kPa, wherein the adsorption column (A) comprises an adsorbent that selectively retains a second gas component XB, while letting out a light current (LCA) which contains component XA and is depleted in components Xc and XB; c) repeating the process of step b) for each gas present in the multicomponent gas mixture M in addition to XA, XB, and Xc, if present, in further adsorption columns, wherein each of these further adsorption columns comprises an adsorbent that selectively retains one of the further gas components, while letting out a light current which is a gas stream depleted in the gas components already adsorbed in the adsorption columns, until the light current is enriched in component XA; d) collecting the third gas component XA; e) recovering the first gas component Xc from the adsorption column (1) by increasing the temperature up to a desorption temperature Tdesl which is in the range from 50 to 250 °C, and then decreasing the pressure to a desorption pressure PV1 which is below atmospheric pressure and is in the range from -100 to -10 kPa; f) recovering the second gas component XB from the adsorption column (A) by increasing the temperature up to a desorption temperature Tdes2 which is in the range from 50 to 250 °C, and then decreasing the pressure to a desorption pressure PV2 which is below atmospheric pressure and is in the range from -100 to -10 kPa; and g) recovering any other adsorbed gas component in addition to XA, XB, and Xc from the adsorption column in which it is adsorbed by increasing the temperature up to a desorption temperature which is in the range from 50 to 250 °C, and then decreasing the pressure to a desorption pressure which is below atmospheric pressure and is in the range from -100 to -10 kPa.

[0023] In particular, in the above process the feeding of the mixture M to the adsorption column (1) is carried out through at least two inlets, with the condition that the feeding is performed alternately through each of the inlets at a given time.

[0024] Brief Description of Drawings

[0025] FIG. 1 shows a simplified flow diagram illustrating a particular embodiment of the process of the invention, wherein step a) comprises feeding a mixture M containing three gas components XA, XB, and Xc to a first adsorption column (1) that selectively retains a first gas component Xc, while letting out a light current (LC1) which contains components XA and XB and is depleted in component Xc; step b) comprises feeding the light current (LC1) to a second adsorption column (A) that selectively retains a second gas component XB, while letting out a light current (LCA) which contains component XA and is depleted in components Xc and XB; step d) comprises collecting the third gas component XA; step e) comprises recovering the first gas component Xc from the adsorption column (1) by desorption; and step f) comprises recovering the second gas component XB from the adsorption column (A) by desorption. The dotted lines represent that the feeding to the column can be carried out alternately (i.e. , not simultaneously) by different inlets.

[0026] FIG. 2A and 2B show simplified flow diagrams illustrating particular embodiments of the process of the invention, wherein step a) comprises feeding a mixture M to a first adsorption column (1) that selectively retains a first gas component Xc, while letting out a light current (LC1) which is depleted in Xc; and feeding the light current (LC1) to a further adsorption column (2) that selectively retains further Xc, while letting out a light current (LC2) which is more depleted in Xc than the stream leaving column (1) (LC1). The dotted lines represent that the feeding to the column can be carried out alternately (i.e., not simultaneously) by different inlets.

[0027] FIG. 3 shows a simplified flow diagram illustrating a particular embodiment of the process of the invention, wherein step b) comprises feeding the light current obtained in step a) (LC1 and / or LC2) to a second adsorption column (A) that selectively retains a second gas component XB, while letting out a light current (LCA) which contains component XA and is depleted in components Xc and XB; and feeding the light current (LCA) to a further adsorption column (B) that selectively retains further gas component XB, while letting out a light current (LCB) which contains component XA and is more depleted in components Xc and Xsthan the stream leaving column (A) (LCA). The dotted lines represent that the feeding to the column can be carried out alternately (i.e., not simultaneously) by different inlets.

[0028] FIG. 4 is a schematic flow diagram that illustrates a particular embodiment of a process cycle for the separation of a gas mixture of three gas components showing consecutive operations 1 / 6, 2 / 7, 3 / 8, 4 / 9, and 5 / 10 as disclosed in Table 1 , wherein operations 1-5 (1 : Pressurization feed (FP), 2: Feed of the mixture (FM), 3: Equalization (EQ), 4: Pressure reduction (DA), 5: Regeneration by temperature and vacuum (TR / VR)) are performed in adsorption column (1), and operations 6-10 (6: Cooling (ER), 7: Clean-up (RL), 8: Equalization (EQ), 9: Compression (CA), 10: Cooling (ER)) are performed in adsorption column (2). The dotted lines represent that the feeding to the column can be carried out alternately (i.e. , not simultaneously) by different inlets.

[0029] FIG. 5 is a schematic flow diagram that illustrates a particular embodiment of a process cycle for the separation of a gas mixture of three gas components showing consecutive operations 11 / 16, 12 / 17, 13 / 18, 14 / 19, and 15 / 20 as disclosed in Table 1 , wherein operations 11-15 (11 : Light current recycle (RL), 12: Light current feed (FL), 13: Pressure reduction (DA), 14: Heavy current recycle (RH), 15: Regeneration by temperature and vacuum (TR / VR)) are performed in adsorption column (A), and operations 16-20 (16: Cooling (ER), 17: Light current clean-up (RL), 18: Compression (CA), 19: Purge step (PR), 20: Cooling (ER)) are performed in adsorption column (B). The dotted lines represent that the feeding to the column can be carried out alternately (i.e., not simultaneously) by different inlets.

[0030] FIG. 6 show simplified flow diagrams illustrating particular embodiments of the process of the invention, wherein the feeding step (FM) in adsorption column (1) is carried out by simultaneously recovering the gas component Xc which has been adsorbed in the adsorption column (2).

[0031] FIG. 7A and 7B represents a schematic flow diagram that illustrates a particular embodiment of a process cycle for the separation of a gas mixture of three gas components showing consecutive operations 1-14 in column (1), operations 15-28 in column (2), operations 29-38, 11-14 in column (A), and operations 15-28 in column (B), where the black rectangles on the sides of the columns represent cooling and the empty rectangles represent heating. FIG. 7B is a continuation of FIG. 7A.

[0032] Detailed description of the invention

[0033] All terms as used herein in this application, unless otherwise stated, shall be understood in their ordinary meaning as known in the art. Other more specific terms as used in the present application are as set forth below and are intended to apply uniformly throughout the specification and claims unless an otherwise expressly set out definition provides a broader definition. For the purposes of the invention, any ranges given include both the lower and the upper endpoints of the range. Ranges given, such as temperatures, times, sizes, and the like, should be considered approximate, unless specifically stated.

[0034] As used herein, the indefinite articles “a” and “an” are synonymous with “at least one” or “one or more.” Thus, as used herein, the singular forms ”a”, “an”, and also the definite article “the” include plural referents unless the context clearly dictates otherwise".

[0035] The term “about” or “around” or “approximately” as used herein refers to a range of values ± 10% of a specified value. For example, the expression “about 10” or “around 10” includes ± 10% of 10, i.e., from 9 to 11.

[0036] The percentages referred herein are molar or volume percentages. The term “molar percentage” (mol%) refers to the percentage of a component (in moles) in relation to the total moles present in a determined mixture provided that the sum of the amounts of the components of the mixture is equal to 100%.

[0037] The term “multicomponent gas mixture” is also referred to as “feed mixture”. Besides, the term “feeding” refers to the introduction of a gas mixture into an adsorption column.

[0038] The terms “adsorption column” or “column” are used herein interchangeably and refer to a hollow structure, in particular a cylindrical structure, enclosing an interior volume which contains the solid adsorbent material. Adsorption columns can also be designated as separation modules. The adsorption column has typically a length (e.g., 2 m) which is higher than its width or diameter (e.g., typical diameter 0.15 m). The adsorption column may have different gas inlets and outlets that can be located at the top of the column, at the bottom of the column, or at one side of the column.

[0039] The term “adsorbent” as used herein refers to the material that selectively captures or retains one component (the heavier one) from a gas mixture. An ideal adsorbent should have high working capacity (high adsorption capacity and good regeneration conditions), large pore dimensions to limit mass transfer resistances, thermal and mechanical stability, and recyclability. Since the process of the invention is a VTPSA process, the adsorbent is regenerated by pressure and temperature swings or variations.

[0040] The terms “heavy current stream” or “heavy component” are used herein interchangeably and refer to the gas component of a gas mixture that is more strongly adsorbed by a given adsorbent material, i.e., the gas component that has higher tendency to be physically retained in the pores of the adsorbent. This means that the adsorbent is more selective or has more affinity for the heavy component. By contrast, the terms “light current” or “light component” refer to the component or component mixture that is weaklier adsorbed or is adsorbed with lower selectivity by the adsorbent material, i.e., the component or component mixture that has lower tendency to be retained in the pores of the adsorbent.

[0041] The expression that an adsorbent “selectively” retains a given gas component Xc refers to the fact that the adsorbent retains or captures such gas component Xc in a higher amount with respect to other gas components present in the same gas mixture (e.g., XA orXs) which are allowed to pass. In one embodiment, optionally in combination with one or more features of the various embodiments described above or below throughout all the description, the expression that an adsorbent selectively retains a given gas component Xc means that the amount of gas component Xc which is retained or captured by the adsorbent (in mol%) is at least 20% higher, more particularly at least 50% higher, even more particularly at least 80% higher, than the amount of any other gas component present in the gas mixture.

[0042] The expression "gas stream depleted in one or more given gas components" means that such one or more given gas components are not present in the gas stream or are present lessened in quantity, i.e., only in a low amount, e.g., in an amount equal to or lower than 30 mol%, more particularly equal to or lower than 20 mol%, and even more particularly equal to or lower than 10 mol%, with respect to the amount in mol% present in the mixture before being introduced into the adsorption column.

[0043] The expression "gas stream enriched in one or more given gas components" means that such one or more given gas components are the amin components in the gas stream, i.e., are present in high amounts, e.g., in an amount equal to or lower than 70 mol%, more particularly equal to or lower than 80 mol%, and even more particularly equal to or lower than 90 mol%, with respect to the amount in mol% present in the mixture before being introduced into the adsorption column.

[0044] The term “off-gas” as used herein refers to the fact that none of the gases of the multicomponent gas mixture to be separated is released into the atmosphere.

[0045] The term “room temperature” as used herein refers to a temperature of the environment, without heating or cooling, and it is generally comprised from 20 °C to 25 °C.

[0046] The term “lateral inlet” as used herein refers to the lateral feed position along the length of the adsorption column. In other words, it refers to an inlet located at an axial part of the adsorption column, being the axial part the longer part of the adsorption column. A lateral inlet is located in a direction transverse to the axial direction, typically in an orthogonal manner such lateral inlets are shown for example in FIG. 2 and 3.

[0047] For the purposes of the invention, the pressures indicated herein refer to absolute pressures, i.e., including the atmospheric pressure. In other words, the pressures as indicated herein refer to the pressures above that of an absolute vacuum (which is zero pressure).

[0048] As used herein, the term "pressurize" means to increase the pressure within the adsorption column with respect to the pressure at which the adsorption column was before the pressurization step. By contrast, the term "depressurize" is intended to mean decreasing the pressure within the adsorption column to a pressure lower than the pressure of the adsorption column before the depressurization step is performed. For example, the pressures of the adsorption columns can be monitored and controlled to automate the process.

[0049] The term “liquefaction pressure” of a mixture of components refers to the pressure at which the gas mixture changes its physical state into a liquid state. Thus, a working pressure which is “below the liquefaction pressure” of a mixture of components refers to a pressure at which the mixture of components is in a gaseous state.

[0050] When in the present invention it is stated that two working pressures are substantially the same, this means that the difference between the two pressure values in absolute value is equal to or lower than 50 kPa, particularly equal to or lower than 10 kPa. When in the present invention it is stated that two temperatures are substantially the same, this means that the difference between the two temperature values in absolute value is equal to or lower than 5 °C, particularly equal to or lower than 1 °C.

[0051] Multicomponent gas mixture

[0052] As mentioned above, the multicomponent gas mixture M comprises at least three (i.e., three or more) gas components XA, XB, and Xc. According to one embodiment, optionally in combination with one or more features of the various embodiments described above or below throughout all the description, the gas components of the multicomponent gas mixture M are refrigerant gases.

[0053] According to one embodiment, optionally in combination with one or more features of the various embodiments described above or below throughout all the description, the multicomponent gas mixture M comprises at least three, at least four, at least five, at least six, at least seven, at least eight, at least nine, at least ten, at least eleven, or at least twelve gas components. The gas components may be present in the mixture in any amount. In one particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, each of the gas components is present in the multicomponent gas mixture in an amount from 0.1 to 98 mol%, wherein the mol percentages (mol%) are given with respect to the total amount of moles in the mixture, and with the condition that the sum of the amounts of the components of the multicomponent gas mixture is equal to 100%.

[0054] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below throughout all the description, the multicomponent gas mixture M consists of three gas components XA, XB, and Xc, i.e., the multicomponent gas mixture M is a ternary mixture, and more particularly the gas components XA, XB, and Xc are refrigerant gases.

[0055] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below throughout all the description, the multicomponent gas mixture M consists of four gas components XA, XB, and Xc, and XD. More particularly the gas components XA, XB, and Xc, and XD are refrigerant gases.

[0056] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below throughout all the description, the multicomponent gas mixture M consists of five gas components XA, XB, and Xc, XD, and XE. More particularly the gas components XA, XB, and Xc, XD, and XE are refrigerant gases.

[0057] The term “refrigerant”, as used herein, refers to a fluid substance used as a thermal energy transfer medium in a refrigeration system to remove heat when it evaporates (changes phase from liquid to vapor). Refrigerants are typically designated by ASHRAE numbers also known as R numbers. Non-limiting examples of refrigerants include chlorofluorocarbons (CFC), chlorofluoroolefins (CFO), hydrochlorofluorocarbons (HCFC), hydrochlorofluoroolefins (HCFO), hydrofluorocarbons (HFC), hydrofluoroolefins (HFO), perfluorocarbons (PFC), perfluoroolefins (PFO), ammonia, carbon dioxide, hydrocarbons (HC) and natural refrigerants (NR).

[0058] For the purposes of the invention, “natural refrigerants” are substances that can be found naturally occurring in the environment in the nature's biological and chemical cycles without human intervention. Natural refrigerants include a range of organic and inorganic compounds suitable for use in a variety of refrigeration and air conditioning system applications and presenting a variety of issues and challenges. Natural refrigerants include ammonia, carbon dioxide, hydrocarbons (including methane R-50, ethane R-170, propane R-290, butane R-600, isobutane R-600a, ethylene R-1150, or propylene R-1270), water, and air.

[0059] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below throughout all the description, the gas components of the multicomponent gas mixture M are refrigerant gases selected from the group consisting of haloalkane refrigerant gases, hydrocarbon refrigerant gases, and a mixture thereof.

[0060] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below throughout all the description, the gas components of the multicomponent gas mixture M are haloalkane refrigerant gases. In a more particular embodiment, the haloalkane refrigerant gases are selected from the group consisting of chlorofluorocarbons (CFC), hydrochlorofluorocarbons (HCFC), hydrofluorocarbons (HFC), perfluorocarbons (PFC), and mixtures thereof. In another more particular embodiment, the haloalkane refrigerant gases are selected from the group consisting of hydrochlorofluorocarbons (HCFC), hydrofluorocarbons (HFC), and mixtures thereof.

[0061] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below throughout all the description, the gas components of the multicomponent gas mixture M are haloalkane refrigerant gases, more particularly selected from the group consisting of chlorofluorocarbons (CFC), hydrochlorofluorocarbons (HCFC), hydrofluorocarbons (HFC), perfluorocarbons (PFC), and mixtures thereof.

[0062] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below throughout all the description, the multicomponent gas mixture is selected from: i) R-407c (23 w / w% R-32 + 25 w / w% R-125 + 52 w / w% R-134a) + R-143a ii) R-407f (30 w / w% R-32 + 30 w / w% R-125 + 40 w / w% R-134a) + R-1234yf iii) R-408a (7 w / w% R-125+ 46 w / w% R-143a + 47 w / w% R-22); iv) R-410 (50 w / w% R-125+ 50 w / w% R-32) + R-143a; v) R-410 (50 w / w% R-125+ 50 w / w% R-32) + R-22; vi) R-410 (50 w / w% R-125+ 50 w / w% R-32) + R-134a; vii) R-507 (50 w / w% R-125 +50 w / w% R-143a) + R-1234yf; viii) R-507 (50 w / w% R-125 +50 w / w% R-143a) + R-32; ix) R-507 (50 w / w% R-125 +50 w / w% R-143a) + R-22; x) R-32 + R-22 + R-134a; xi) R-1234yf + R-22 + R-125; xii) R-1234yf + R-22 + R-32; and xiii) R-1234yf + R-143 + R-32. wherein:

[0063] R-22 is chlorodifluoromethane, R-32 is difluoromethane, R-125 is pentafluoroethane, R- 134a is 1 ,1 ,1 ,2-tetrafluoroethane, R-143a is 1 ,1 ,1 -trifluoroethane, and R-1234yf is 2, 3, 3, 3- tetrafluoropropene.

[0064] Adsorbents

[0065] The separation process of the invention is based on the different affinity of a gas component (heavy current) and another gas component or components contained in the multicomponent gas mixture for an adsorbent material. The different affinities are adjusted through the different steps and parametric control over the process design to create the most reduced zone of mass transfer and create a purified light current.

[0066] Non-limiting examples of adsorbent materials include zeolites, metal-organic frameworks (MOFs), silicalites, aluminosilicates, titanosilicates, germanosilicates, covalent-organic frameworks, carbon molecular sieves (CMSs), activated carbon, or silica gel. If a combination of two or more adsorbent materials is used the adsorbents can be of different type, e.g., aluminosilicates and zeolites, or of the same type e.g., with different particle size, e.g., 1.5 mm zeolite and 3 mm zeolite.

[0067] As used herein, the term "zeolite" refers to an open three-dimensional framework structure composed of tetrahedrally-coordinated atoms ("T-atoms") connected with oxygen atoms. Typically, the T-atoms include silicon and aluminum, but may also include phosphorus, titanium, beryllium, germanium, and other metals. The structure may also include extraframework cations, such as hydrogen, sodium, potassium, barium, calcium, magnesium, iron, gallium, germanium, and others. Traditional zeolites include zeolites A, X and Y. The present invention encompasses zeolites with binder containing beads or pellets as well as binderless zeolites, monoliths shaped zeolites, 3D printed shapes or coated materials with zeolite.

[0068] Activated carbon can be conveniently obtained from natural products by proper thermal and / or chemical treatment. Activated carbon can be tailor-made with pore widths in the range of some tenths of a nanometer, giving rise to carbon molecular sieves.

[0069] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the adsorbents are selected from the group consisting of zeolites, activated carbons, metallic organic structures (MOF), and combinations thereof.

[0070] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the adsorbent is selected from the group consisting of activated carbon, zeolite, and mixtures thereof, more particularly, the zeolite is selected from the group consisting of zeolite 4A, zeolite 5A, zeolite 13X, zeolite APG III, and mixtures thereof.

[0071] The adsorbent to be used in each case depends on the gas mixture to be separated. The skilled person can determine by routine tests the most adequate adsorbent for each particular mixture.

[0072] Process

[0073] The present invention relates to an adsorption-desorption process for the recovery of gas components, in particular refrigerant gases, from a multicomponent gas mixture without offgas. The term “adsorption-desorption process” as used herein refers to the fact that the process comprises at least two adsorption steps (steps a and b), in which different gas components are adsorbed onto an adsorbent material, and at least two desorption steps (steps d and e), in which the component that had been previously adsorbed is desorbed from the adsorbent material by temperature and vacuum, and the adsorbent is thus regenerated.

[0074] The VTPSA process of the invention comprises at least one cycle of steps a) to g) as defined above. In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the process of the invention and comprises at least two cycles as defined above.

[0075] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the process comprises more than one cycle of steps as disclosed herein.

[0076] As mentioned above, the process of the invention is carried out with a number of adsorption columns nc which is either nx-1 , or alternatively a multiple of nx-1 , wherein nxis the number of the gas components of the multicomponent gas mixture M.

[0077] The process of the invention may be adapted depending to the needed capacity for separating multicomponent mixtures. Advantageously, the production capacity may be enhanced by increasing the number of columns used for the separation in such a way that each of the columns that performs a cycle of the process of the invention (i.e. , columns 1 and A) comprises two or more single columns (1) connected to each other in parallel or in row.

[0078] Thus, in one particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the number of adsorption columns nc used in the process of the invention is a multiple of nx-1 , more particularly, i.e., the number of adsorption columns nc is nc = R (nx-1), wherein R is a value from 2 to 16, even more particularly, R is 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, or 16. For example, in this embodiment, when the number of the gas components of the multicomponent gas mixture M (nx) is 3, the process is carried out using R pairs of columns.

[0079] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the number of adsorption columns nc is nx-1 .

[0080] The process of the invention may operate in a discontinued manner or continuously. For example, when the multicomponent gas mixture M consists of three gas components XA, XB, and Xc, the number of adsorption columns used in the process is at least 2: columns (1) and (A) as shown in FIG. 1. To operate the system in a continuous manner, columns (2) and (B) may be used as explained below and shown in FIG.4 and FIG. 5.

[0081] As it will be explained in more detail below, in the process of the invention the feeding of the gas mixture M may be carried out through at least two inlets, with the condition that the feeding is performed alternately through each of the inlets at a given time. Similarly, the recovery of the heavier gas components XB and Xc may be carried out through at least two inlets, with the condition that the recovery is performed alternately through each of the inlets at a given time. This is advantageous in terms of yield, purity and allows reducing the cycles of the process.

[0082] Feed of the mixture (FM) into adsorption column (1)

[0083] In step a) of the process of the invention a multicomponent gas mixture M, which comprises at least three gas components XA, XB, and Xc, is introduced to an adsorption column (1) at a suitable working pressure HP1 , wherein the adsorption column (1) comprises an adsorbent that selectively retains a first gas component Xc. Simultaneously, a light current (LC1) which contains components XA and XB and is depleted in component Xc is let out from the adsorption column (1).

[0084] Components XA and XB and optionally further gas components other than Xc (lighter components) have lower affinity for the adsorbent of the adsorbent column (1) in comparison to Xc (heavier component) and mainly pass through the adsorbent without being retained and exit the adsorption column more easily than component Xc.

[0085] The working pressure HP1 of step a) is in the range from 100 to 6000 kPa, more particularly from 200 to 5000 kPa, depending on the mixture to be separated. In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the working pressure HP1 of step a) is about 100 kPa, about 200 kPa, about 500 kPa, about 800 kPa, about 1000 kPa, about 1200 kPa, about 1500 kPa, about 1800 kPa, about 2000 kPa, about 2200 kPa, about 2500 kPa, about 2800 kPa, about 3000 kPa, about 3200 kPa, about 3500 kPa, about 3800 kPa, about 4000 kPa, about 4200 kPa, about 4500 kPa, about 4800 kPa, about 5000 kPa, or about 6000 kPa.

[0086] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the working pressure HP1 of step a) is below the liquefaction pressure of the mix components.

[0087] According to one embodiment, optionally in combination with one or more features of the various embodiments described above or below, step a) is carried out at a temperature from -20 to 80 °C, more particularly from -10 to 60 °C, depending on the mixture to be separated. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, step a) is carried out at a temperature about -20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, or about 80 °C.

[0088] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the amount of gas component Xc of the gas mixture M which is retained or captured by the adsorbent (in mol%) is at least 20% higher, more particularly at least 50% higher, even more particularly at least 80% higher, than the amount retained or captured by the adsorbent of any of XA and XB present in the gas mixture M.

[0089] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the first gas component Xc is present in the light current (LC1) in an amount equal to or lower than 30 mol%, more particularly equal to or lower than 20 mol%, and even more particularly equal to or lower than 10 mol%, with respect to the amount in mol% of gas component Xc present in the multicomponent mixture M.

[0090] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding is carried out until the relative concentration of the gas component Xc in the light current (LC1) with respect to its concentration in the initial multicomponent gas mixture M is equal to or lower than 30 mol%, more particularly equal to or lower than 20 mol%, and even more particularly equal to or lower than 10 mol%. Then, in this embodiment the feeding and the removal of the light current (LC1) is stopped by closing the corresponding inlet and outlet.

[0091] Typically, the feeding of the gas mixture M into the adsorption column (1) may be carried out through one or more inlets located at different positions of the adsorption column (1). In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the multicomponent gas mixture M to the adsorption column (1) is carried out through an inlet located at the bottom of the adsorption column (1). In one alternative embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the multicomponent gas mixture M to the adsorption column (1) is carried out through an inlet located at the top of the adsorption column (1). In another alternative embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the multicomponent gas mixture M to the adsorption column (1) is carried out through a lateral inlet of the adsorption column (1).

[0092] The feeding of the gas mixture M into the adsorption column (1) is particularly carried out through at least two inlets, with the condition that the feeding is performed alternately through each of the inlets at a given time. More particularly, the inlets are located at different parts of the column such including a top inlet, a lateral inlet and a bottom inlet. This means that only one inlet is used at a given time for a suitable period of time. In other words, the feeding is not simultaneously carried out through more than one inlet. This configuration is especially advantageous for refrigerant gases since allows the entry of cold gas into the column thereby reducing the temperature difference along the column which is produced when single feeding is used due to the heat generated by the gas when adsorbed. As shown in the examples this allows increasing both the yield of the separation and the purity of the separated gases at the same time.

[0093] In one particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding is carried out through two inlets, more particularly wherein the first inlet is located at the top the adsorption column (1) and the second inlet is a lateral inlet in the adsorption column (1), with the condition that the feeding is performed either through the top inlet or the lateral inlet at a given time, but not simultaneously through the two inlets. In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of gas mixture M to the adsorption column (1) is carried out through two inlets, wherein the first inlet is located at the bottom of the adsorption column (1) and the second inlet is a lateral inlet in the adsorption column (1), with the condition that the feeding is performed either through the bottom inlet or the lateral inlet at a given time, but not simultaneously through the two inlets.

[0094] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the multicomponent gas mixture M is a liquefied mixture (i.e. , the gas mixture is in a liquid state) and prior to the feeding into the adsorption column (1) the multicomponent gas mixture M is converted from the liquid state to a gas state for example by means of an expansion valve.

[0095] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, during the feeding of gas mixture M, the adsorption column (1) is cooled particularly by cooling column jackets and / or serpentine coils and / or finned tubes, more particularly when the feeding is carried out through an inlet located at the top of the adsorption column (1).

[0096] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the light current (LC1) depleted in component Xc is let out from the adsorption column (1) through an outlet located at the top of the adsorption column (1).

[0097] Regeneration by vacuum (VR) in adsorption column (2)

[0098] The process of the invention can be operated by additional columns in order to achieve a better separation of the components. Additionally, the use of further columns allows the process to be operated in a continuous manner. Thus, in one embodiment, optionally in combination with one or more features of the various embodiments described above or below, particularly wherein the multicomponent gas mixture M consists of three gas components XA, XB, and Xc, the feeding step (FM) is carried out by simultaneously recovering the gas component Xc which has been adsorbed in the adsorption column (2). This step is carried out by decreasing the pressure to a desorption pressure PV1 which is below atmospheric pressure and is in the range from -90 to -50 kPa. Particular embodiments of this configuration are shown in FIG. 6.

[0099] According to one embodiment, optionally in combination with one or more features of the various embodiments described above or below, this step (VR) is carried out at a pressure PV1 in the range from -100 to -10 kPa, more particularly from -90 to -50 kPa, depending on the component to be recovered. In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure PV1 of step e) is about -100 kPa, about -90 kPa, about -80 kPa, about -70 kPa, about -60 kPa, about -50 kPa, about -40 kPa, about -30 kPa, about -20 kPa, or about -10 kPa.

[0100] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the recovery of the gas component Xc (VR) from the adsorption column (2) is carried out through an inlet located at the top of the adsorption column (2). In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the recovery of the gas component Xc (VR) from the adsorption column (2) is carried out through an inlet located at the bottom of the adsorption column (2). In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the recovery of the gas component Xc (VR) from the adsorption column (2) is carried out through a lateral inlet of the adsorption column (2).

[0101] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the recovery of the gas component Xc (VR) from the adsorption column (2) is carried out through at least two inlets, with the condition that the feeding is performed alternately through each of the inlets at a given time. More particularly, the recovery of the gas component Xc (VR) from the adsorption column (2) is carried out through two inlets, more particularly wherein the first inlet is located at the top the adsorption column (2) and the second inlet is a lateral inlet in the adsorption column (2), with the condition that the recovery is performed either through the top inlet or the lateral inlet at a given time, but not simultaneously through the two inlets.

[0102] Heavy current recycle (RH) in adsorption column (1)

[0103] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, when the process is carried out with an additional column (2) as explained herein, after the recovery of Xc (VR) is stopped, the process comprises introducing a stream of pure gas component Xc into the adsorption column (1), and simultaneously letting out from the adsorption column (1) a light current which contains component XA and is depleted in component Xc and XB. In this step the pressure of the adsorption column (1) is lower than the pressure of the adsorption column (2). A particular embodiment of this configuration is shown in FIG. 7.

[0104] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the stream of pure gas component Xc is introduced into the adsorption column (1) through an inlet located at the top of the adsorption column (1).

[0105] Clean-up (RL) in adsorption column (2)

[0106] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, particularly wherein the multicomponent gas mixture M consists of three gas components XA, XB, and Xc, step a) further comprises feeding the light current (LC1), obtained after step (FM) or (RH) for example, to a further adsorption column (2) at a suitable working pressure LP1 which is lower than the working pressure HP1 , wherein the adsorption column (2) comprises an adsorbent that selectively retains further gas component Xc. Simultaneously, a light current (LC2) which contains components XA and XB and is depleted in component Xc is let out from the adsorption column (2). Particular embodiments of this configuration are shown in FIG. 4 and FIG. 7.

[0107] The light current (LC2) is more depleted in Xcthan the light current (LC1), i.e. , it contains a lower amount of Xc. In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the gas component Xc is present in the light current (LC2) in an amount equal to or lower than 30 mol%, more particularly equal to or lower than 20 mol%, and even more particularly equal to or higher than 10 mol%, with respect to the amount in mol% of gas component Xc present in the multicomponent mixture M.

[0108] The working pressure LP1 is in the range from 100 to 3000 kPa, more particularly from 100 to 2000 kPa, depending on the mixture to be separated. In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the working pressure LP1 is about 100 kPa, about 200 kPa, about 500 kPa, 800 kPa, about 1000 kPa, about 1200 kPa, about 1500 kPa, about 1800 kPa, about 2000 kPa, about 2200 kPa, about 2500 kPa, about 2800 kPa or about 3000 kPa.

[0109] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the working pressure LP1 is below the liquefaction pressure of the mix components.

[0110] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the working pressure LP1 is lower than the working pressure HP1 , more particularly LP1 is at least about 20%, particularly is about 50% lower than HP1. According to one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the light current (LC1) to a further adsorption column (2) is carried out at a temperature from -20 to 80 °C, more particularly from -10 to 60 °C, depending on the mixture to be separated. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, step a) is carried out at a temperature about -20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, or about 80 °C.

[0111] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the light current (LC1) to a further adsorption column (2) is carried out at substantially the same temperature of the previous step (feeding of the multicomponent gas mixture M to the adsorption column (1) (FM)).

[0112] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the multicomponent gas mixture M to the adsorption column (1) and the feeding of the light current (LC1) to the adsorption column (2) is carried out simultaneously as shown in FIG. 2A or FIG. 2B.

[0113] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the light current (LC1) to the adsorption column (2) is carried out until the relative concentration of the heavy gas component Xc in the light current (LC2) with respect to its concentration in the initial multicomponent gas mixture M is equal to or lower than 30 mol%, more particularly equal to or lower than 20 mol%, and even more particularly equal to or higher than 10 mol%. Then, in this embodiment the feeding of the light current (LC1) and the removal of the light current (LC2) is stopped by closing the corresponding inlet and outlet.

[0114] The feeding of the light current (LC1) to the adsorption column (2) may be carried out through one or more inlets located at different positions of the adsorption column (2). In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the multicomponent gas mixture M to the adsorption column (2) is carried out through an inlet located at the top of the adsorption column (2). In one alternative embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the light current (LC1) to the adsorption column (2) is carried out through an inlet located at the bottom of the adsorption column (2). In another alternative embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding light current (LC1) to the adsorption column (2) is carried out through a lateral inlet of the adsorption column (2).

[0115] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the light current (LC1) to the adsorption column (2) is carried out through at least two inlets, with the condition that the feeding is performed alternately through each of the inlets at a given time. More particularly, the inlets are located at different parts of the column such including a top inlet, a lateral inlet or a bottom inlet. In a more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the light current (LC1) to the adsorption column (2) is carried out through two inlets, wherein the first inlet is located at the top of the adsorption column (2) and the second inlet is a lateral inlet in the adsorption column (2), with the condition that the feeding is performed either through the top inlet or the lateral inlet at a given time but not simultaneously through the two inlets.

[0116] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the light current (LC2) depleted in component Xc is let out from the adsorption column (2) through an inlet located at bottom of the adsorption column (2).

[0117] Pressurization feed (FP) of adsorption column (1)

[0118] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the process of the invention further comprises a previous pressurization step before step a) which comprises pressurizing the adsorption column (1) by introducing the multicomponent gas mixture M into the adsorption column (1) until the working pressure HP1 as defined above is reached.

[0119] According to one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressurization step (FP) before step a) is carried out at a temperature from -20 to 80 °C, more particularly from -10 to 60 °C, depending on the mixture to be separated. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, step a) is carried out at a temperature about -20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, or about 80 °C.

[0120] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressurization step (FP) before step a) is carried out at substantially the same temperature of the next step (feeding of the multicomponent gas mixture M to the adsorption column (1) (FM)).

[0121] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the multicomponent gas mixture M to the adsorption column (1) for pressurization purposes is carried out through an inlet located at the bottom of the adsorption column (1). In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the multicomponent gas mixture M to the adsorption column (1) for pressurization purposes is carried out through an inlet located at the top of the adsorption column (1).

[0122] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the multicomponent gas mixture M is a liquefied mixture (i.e., the gas mixture is in a liquid state) and prior to the feeding into the adsorption column (1) the multicomponent gas mixture M is converted from the liquid state to a gas state for example by means of an expansion valve.

[0123] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, during the feeding of the multicomponent gas mixture M, the adsorption column (1) is cooled particularly by cooling column jackets and / or serpentine coils and / or finned tubes.

[0124] Cooling (ER) and regeneration by decompression (DR) in adsorption column (2)

[0125] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, when the process is carried out with an additional column (2), the pressurization step (FP) before step a) is carried out by simultaneously cooling (ER) the adsorption column (2). A particular embodiment of this configuration is shown in FIG. 4.

[0126] In one particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the adsorption column (2) during the cooling (ER) is in the range from -20 to 80 °C, more particularly from -10 to 60 °C. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the adsorption column (2) is about -20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, or about 80 °C.

[0127] According to another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the cooling (ER) of the adsorption column (2) is carried out at a pressure which is in the range from 10 to 800 kPa. In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the cooling of the adsorption column (2) is carried out at a pressure which is about 10 kPa, about 50 kPa, about 100 kPa, about 150 kPa, about 200 kPa, about 250 kPa, about 300 kPa, about 350 kPa, about 400 kPa, about 450 kPa, about 500 kPa, about 550 kPa, about 600 kPa, about 650 kPa, about 700 kPa, about 750 kPa, or about 800 kPa.

[0128] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure of this step (ER) is about 100 kPa.

[0129] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, when the process is carried out with an additional column (2), the pressurization step (FP) before step a) is carried out by simultaneously decompressing (DR) the adsorption column (2) and recovering the gas component Xc which has been adsorbed in the adsorption column (2), wherein the pressure is decreased to a desorption pressure which is below atmospheric pressure and is in the range from -90 to -50 kPa. A particular embodiment of this configuration is shown in FIG. 7. More particularly,

[0130] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the recovery of the gas component Xc from the adsorption column (2) is carried out through an inlet located at the top of the adsorption column (2).

[0131] Equalization step (EQ, ED, EP) in adsorption columns (1) and (2)

[0132] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, when the process is carried out with an additional column (2) as explained herein, step a) further comprises an equalization step after the clean-up step (RL) is stopped. The equalization step comprises transferring pressure from the adsorption column (1) at a working pressure HP1 to the adsorption column (2) at a working pressure LP1 until the pressure values of the adsorption column (1) and the adsorption column (2) are substantially the same.

[0133] According to one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the column (1) in the equalization step is from -20 to 80 °C, more particularly from -10 to 60 °C, depending on the mixture to be separated. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the column (1) in the equalization step is about -20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, or about 80 °C.

[0134] According to another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the column (2) in the equalization step is from -20 to 80 °C, more particularly from -10 to 60 °C, depending on the mixture to be separated. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the column (2) in the equalization step is about -20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, or about 80 °C.

[0135] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the column (1) in the equalization step is substantially the same as the temperature of the column (2) in the equalization step. More particularly, the temperature of the columns (1) and (2) in the equalization step is substantially the same temperature as the one of the previous step (feeding FM or RL).

[0136] Pressure reduction (DA) and compression (CA) in adsorption columns (1) and (2)

[0137] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, when the process is carried out with an additional column (2), step a) further comprises a depressurization-compression step after the equalization step (EQ, ED, EP). This depressurization-compression step comprises extracting the remaining pressure in column (1) from the previous equalization step in a pressure reduction step (DA) to a final value of LP1 (low pressure). In the meantime, in the column (2) through a compression step (CA) the pressure is increased to a HP1 value, such that the remaining material coming from column (1) is compressed.

[0138] In one particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure of the adsorption column (1) is reduced until a value LP1 which is in the range from 100 to 3000 kPa, more particularly from 100 to 1000 kPa, and the pressure of the adsorption column (2) is increased until a value HP1 which is in the range from 100 to 6000 kPa, more particularly from 200 to 5000 kPa, with the condition that the pressure of the adsorption column (1) is lower than the pressure of the adsorption column (2).

[0139] In another particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure of the adsorption column (1) is reduced in DA until a value about is about 100 kPa, about 200 kPa, about 500 kPa, about 800 kPa, about 1000 kPa, about 1200 kPa, about 1500 kPa, about 1800 kPa, about 2000 kPa, about 2200 kPa, about 2500 kPa, about 2800 kPa, or about 3000 kPa.

[0140] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure of the adsorption column (2) is increased in CA until a value about 100 kPa, about 200 kPa, about 500 kPa, 800 kPa, about 1000 kPa, about 1200 kPa, about 1500 kPa, about 1800 kPa, about 2000 kPa, about 2200 kPa, about 2500 kPa, about 2800 kPa, about 3000 kPa, about 3200 kPa, about 3500 kPa, about 3800 kPa, about 4000 kPa, about 4200 kPa, about 4500 kPa, about 4800 kPa, about 5000 kPa, or about 6000 kPa.

[0141] According to one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the column (1) in the depressurization-compression step after the equalization step (EQ / ED / EP) is from -20 to 80 °C, more particularly from -10 to 60 °C, depending on the mixture to be separated. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the column (1) in the depressurization-compression step is about -20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, or about 80 °C.

[0142] According to one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the column (2) in the depressurization-compression step after the equalization step (EQ / ED / EP) is from -20 to 80 °C, more particularly from -10 to 60 °C, depending on the mixture to be separated. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the column (2) in the depressurization-compression step is about -20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, or about 80 °C.

[0143] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the column (1) in the equalization step is substantially the same as the temperature of the column (2) in the depressurization-compression step. More particularly, the temperature of the columns (1) and (2) in the depressurization-compression step is substantially the same temperature as the one of the previous step (equalization EQ / ED / EP). In one particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the depressurization-compression step further comprises introducing a stream of pure gas component Xc into the adsorption column (1) while reducing the pressure of the adsorption column (1) and simultaneously increasing the pressure of the adsorption column (2), such that the pressure of the adsorption column (1) is transferred to the adsorption column (2). More particularly, the stream of pure gas component Xc is introduced to adsorption column (1) through an inlet located at top of the adsorption column (1).

[0144] Regeneration by temperature and vacuum (TR / VR) and regeneration by temperature (TR) in adsorption column (1)

[0145] In step e) of the process of the invention the gas component Xc which has been adsorbed in the adsorption column (1) is recovered from the said column by desorption. Step e) is carried out by increasing the temperature up to a desorption temperature Tdesl which is in the range from 50 to 250 °C, and then decreasing the pressure to a desorption pressure PV1 which is below atmospheric pressure and is in the range from -90 to -50 kPa. Thus, the temperature of the adsorption column (1) in step e) is higher than the temperature of the adsorption column (1) in step a), and the pressure of the adsorption column (1) in step e) is lower than the pressure of the adsorption column (1) in step a).

[0146] In this step not only the gas component Xc is recovered but also the adsorbent in the adsorption column (1) is regenerated and thus can be reused in other cycles of the process.

[0147] According to one embodiment, optionally in combination with one or more features of the various embodiments described above or below, step e) is carried out at a pressure PV1 in the range from -100 to -10 kPa, more particularly from -90 to -50 kPa, depending on the component to be recovered. In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure PV1 of step e) is about -100 kPa, about -90 kPa, about -80 kPa, about -70 kPa, about -60 kPa, about -50 kPa, about -40 kPa, about -30 kPa, about -20 kPa, or about -10 kPa.

[0148] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, step e) is carried out at a temperature Tdesl from 50 to 250 °C, more particularly from 90 to 150 °C, depending on the component to be recovered. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, step e) is carried out at a temperature about 50 °C, about 60 °C, about 70 °C, about 80 °C, about 90 °C, about 100 °C, about 110 °C, about 120 °C, about 130 °C, about 140 °C, about 150 °C, about 160 °C, about 170 °C, about 180 °C, about 190 °C, about 200 °C, about 210 °C, about 220 °C, about 230 °C, about 240 °C, or about 250 °C.

[0149] Alternatively, the gas component Xc which has been adsorbed in the adsorption column (1) may be recovered from the said column by desorption by increasing the temperature up to a desorption temperature Tdesl which is in the range from 50 to 250 °C.

[0150] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the recovery of the gas component Xc from the adsorption column (1) is carried out through an inlet located at the bottom of the adsorption column (1). In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the recovery of the gas component Xc from the adsorption column (1) is carried out through an inlet located at the top of the adsorption column (1).

[0151] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, during the recovery step (VR), the adsorption column (1) is heated particularly by heating column jackets and / or serpentine coils and / or finned tubes.

[0152] Cooling (ER) in adsorption column (2)

[0153] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, when the process is carried out with an additional column (2), step e) is carried out by simultaneously cooling the adsorption column (2) after the depressurization-compression step.

[0154] In one particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the adsorption column (2) is in the range from -20 to 80 °C, more particularly from -10 to 60 °C. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the adsorption column (2) is about -20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, or about 80 °C.

[0155] According to another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the cooling of the adsorption column (2) is carried out at substantially the same pressure as the pressure in column (1) in step e), which is in the range from -100 to 10 kPa. In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure PV1 of step e) is about -90 kPa. In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure PV1 of step e) is about -100 kPa, about -90 kPa, about -80 kPa, about -70 kPa, about -60 kPa, about -50 kPa, about -40 kPa, about -30 kPa, about -20 kPa, or about -10 kPa.

[0156] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, during the cooling step (ER), the adsorption column (2) is cooled particularly by cooling column jackets and / or serpentine coils and / or finned tubes.

[0157] Light current feed (FL) in adsorption column (A)

[0158] In step b) of the process of the invention the light current obtained in step a) is introduced to an adsorption column (A) at a suitable working pressure HP2, wherein the adsorption column (A) comprises an adsorbent that selectively retains a second gas component XB. Simultaneously, light current (LCA) which contains component XA and is depleted in components Xc and XB is let out from the adsorption column (A).

[0159] Component XA and optionally further gas components other than XB and Xc (lighter components) have lower affinity for the adsorbent of the adsorbent column (A) in comparison to XB (heavier component) and mainly pass through the adsorbent without being retained and exit the adsorption column more easily than component XB.

[0160] The working pressure HP2 is in the range from 100 to 6000 kPa, more particularly from 200 to 5000 kPa, depending on the mixture to be separated.

[0161] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the working pressure HP2 is below the liquefaction pressure of the mix components.

[0162] The working pressure HP2 in column (A) may be the same or different than the working pressure HP1 in column (1). According to one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the working pressure HP1 and the working pressure HP2 are the same. In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the working pressure HP1 and the working pressure HP2 are different, more particularly the working pressure HP2 is lower than the working pressure HP1 , more particularly HP2 is at least 5% lower than HP1 , particularly HP2 is about 10% lower than HP1. In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the working pressure HP2 of step b) is about 100 kPa, about 200 kPa, about 500 kPa, about 800 kPa, about 1000 kPa, about 1200 kPa, about 1500 kPa, about 1800 kPa, about 2000 kPa, about 2200 kPa, about 2500 kPa, about 2800 kPa, about 3000 kPa, about 3200 kPa, about 3500 kPa, about 3800 kPa, about 4000 kPa, about 4200 kPa, about 4500 kPa, about 4800 kPa, about 5000 kPa, or about 6000 kPa.

[0163] According to one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the light current (LCA) to a further adsorption column (A) is carried out at a temperature from -20 to 80 °C, more particularly from -10 to 60 °C, depending on the mixture to be separated. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, step b) is carried out at a temperature about -20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, or about 80 °C.

[0164] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the light current (LCA) to a further adsorption column (A) is carried out at substantially the same temperature of step a) (feeding of the multicomponent gas mixture M to the adsorption column (1) (FM) or feeding the light current (LC1) to a further adsorption column (2) (RL)).

[0165] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the amount of gas component XB present in LC1 or LC2 which is retained or captured by the adsorbent (in mol%) is at least 20% higher, more particularly at least 50% higher, even more particularly at least 80% higher, than the amount retained or captured by the adsorbent of any of XA and Xc present in LC1 or LC2.

[0166] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the gas component XB is present in the light current (LCA) in an amount equal to or lower than 30 mol%, more particularly equal to or lower than 20 mol%, and even more particularly equal to or higher than 10 mol%, with respect to the amount in mol% of gas component XB present in the multicomponent mixture M.

[0167] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding is carried out until the relative concentration of the gas component XB in the light current (LCA) with respect to its concentration in the initial multicomponent gas mixture M is equal to or lower than 30 mol%, more particularly equal to or lower than 20 mol%, and even more particularly equal to or higher than 10 mol%. Then, in this embodiment the feeding and the removal of the light current (LCA) is stopped by closing the corresponding inlet and outlet.

[0168] The feeding of the light current feed (FL) into the adsorption column (A) may be carried out through one or more inlets located at different positions of the adsorption column (A). In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the light current obtained in step a) to the adsorption column (A) is carried out through an inlet located at the bottom of the adsorption column (A). In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the light current obtained in step a) to the adsorption column (A) is carried out through an inlet located at the top of the adsorption column (A). In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the light current obtained in step a) to the adsorption column (A) is carried out through a lateral inlet of the adsorption column (A).

[0169] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of light current (LCA) to the adsorption column (A) is carried out through two inlets, wherein the first inlet is located at the bottom of the adsorption column (A) and the second inlet is a lateral inlet in the adsorption column (A).

[0170] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the light current (LCA) depleted in components Xc and XB is let out from the adsorption column (A) through an inlet located at the top of the adsorption column (A). In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the light current (LCA) depleted in components Xc and XB is let out from the adsorption column (A) through an inlet located at the bottom of the adsorption column (A). In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the light current (LCA) depleted in components Xc and XB is let out from the adsorption column (A) through a lateral inlet of the adsorption column (A).

[0171] When the multicomponent gas mixture comprises further gas components in addition to XA, XB, and Xc, the process of the invention further comprises step c) which comprises repeating an analog process to step b) for each additional gas if present. Thus, the mixture containing component XA and further gases which is depleted in components Xc and XB is passed through further adsorption columns which comprise adsorbents that selectively retain each time one of the further gas components, while letting out a light current which is a gas stream depleted in the gas components already adsorbed in the adsorption columns. This process is repeated until a light current is obtained which is enriched in component XA and depleted in any other gas components. The pressure and temperature conditions indicated for step b) apply to these additional steps.

[0172] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, during the decompression step, the adsorption column (A) is cooled particularly by cooling column jackets and / or serpentine coils and / or finned tubes.

[0173] Regeneration by vacuum (VR) in adsorption column (B)

[0174] As mentioned above, the process of the invention can be operated by additional columns in order to achieve a better separation of the components. Additionally, the use of further columns allows the process to be operated in a continuous manner. Thus, in one embodiment, optionally in combination with one or more features of the various embodiments described above or below, step FL in column (A) is carried out by simultaneously recovering the gas component XB which has been adsorbed in the adsorption column (B). This step is carried out by decreasing the pressure to a desorption pressure PV1 which is below atmospheric pressure and is in the range from -90 to -50 kPa.

[0175] According to one embodiment, optionally in combination with one or more features of the various embodiments described above or below, this step (VR) is carried out at a pressure PV1 in the range from -100 to -10 kPa, more particularly from -90 to -50 kPa, depending on the component to be recovered. In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure PV1 of step e) is about -100 kPa, about -90 kPa, about -80 kPa, about -70 kPa, about -60 kPa, about -50 kPa, about -40 kPa, about -30 kPa, about -20 kPa, or about -10 kPa.

[0176] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the recovery of the gas component XB (VR) from the adsorption column (B) is carried out through an inlet located at the top of the adsorption column (B). In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the recovery of the gas component XB (VR) from the adsorption column (B) is carried out through an inlet located at the bottom of the adsorption column (B). In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the recovery of the gas component XB (VR) from the adsorption column (B) is carried out through a lateral inlet of the adsorption column (B). In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the recovery of the gas component XB (VR) from the adsorption column (B) is carried out through at least two inlets, with the condition that the feeding is performed alternately through each of the inlets at a given time. More particularly, the recovery of the gas component XB (VR) from the adsorption column (B) is carried out through two inlets, more particularly wherein the first inlet is located at the bottom the adsorption column (B) and the second inlet is a lateral inlet in the adsorption column (B), with the condition that the recovery is performed either through the top inlet or the lateral inlet at a given time, but not simultaneously through the two inlets.

[0177] Heavy current recycle (RH) in adsorption column (A)

[0178] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, when the process is carried out with an additional column (B) as explained herein, after the recovery of XB (VR) is stopped, the process comprises introducing a stream of pure gas component XB into the adsorption column (A), and simultaneously letting out from the adsorption column (A) a light current which contains component XA and is depleted in component Xc and XB. In this step the pressure of the adsorption column (A) is lower than the pressure of the adsorption column (B). A particular embodiment of this configuration is shown in FIG. 7.

[0179] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the stream of pure gas component XB is introduced into the adsorption column (A) through an inlet located at the top of the adsorption column (A).

[0180] Light current clean-up (RL) in adsorption column (B)

[0181] Thus, in one embodiment, optionally in combination with one or more features of the various embodiments described above or below, step b) further comprises feeding the light current (LCA), obtained after step (FL) for example, to a further adsorption column (B) at a suitable working pressure LP2, which is lower than the working pressure PH2, wherein the adsorption column (B) comprises an adsorbent that selectively retains further gas component XB. Simultaneously, a light current (LCB) which contains component XA and is depleted in component Xc and XB is let out from the adsorption column (B).

[0182] The light current (LCB) is more depleted in Xs than the light current (LCA), i.e. , is contains a lower amount of XB. In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the gas component XB is present in the light current (LCB) in an amount equal to or lower than 30 mol%, more particularly equal to or lower than 20 mol%, and even more particularly equal to or higher than 10 mol%, with respect to the amount in mol% of gas component XB present in the multicomponent mixture M.

[0183] The working pressure LP2 is in the range from 100 to 3000 kPa, more particularly from 100 to 2000 kPa, depending on the mixture to be separated. In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the working pressure LP2 is about 100 kPa, about 200 kPa, about 500 kPa, 800 kPa, about 1000 kPa, about 1200 kPa, about 1500 kPa, about 1800 kPa, about 2000 kPa, about 2200 kPa, about 2500 kPa, about 2800 kPa or about 3000 kPa.

[0184] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the working pressure LP2 is below the liquefaction pressure of the mix components.

[0185] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the working pressure LP2 is lower than the working pressure HP2, more particularly LP2 is at least about 10%, particularly is about 50% lower than HP2.

[0186] According to one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the light current (LCA) to a further adsorption column (B) is carried out at a temperature from -20 to 80 °C, more particularly from -10 to 60 °C, depending on the mixture to be separated. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, step a) is carried out at a temperature about -20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, or about 80 °C.

[0187] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the light current (LCA) to a further adsorption column (B) is carried out at substantially the same temperature of the previous step (feeding of the light current obtained in step a) to the adsorption column (A) (FL)).

[0188] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the light current (LC1) or (LC2) to the adsorption column (A) and the feeding of the light current (LCA) to the adsorption column (B) is carried out simultaneously as shown in FIG. 3 or FIG. 7. In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the light current (LCA) to the adsorption column (B) is carried out until the relative concentration of the heavy gas component XB in the light current (LC2) with respect to its concentration in the initial multicomponent gas mixture M is equal to or lower than 30 mol%, more particularly equal to or lower than 20 mol%, and even more particularly equal to or higher than 10 mol%. Then, in this embodiment the feeding of the light current (LCA) and the removal of the light current (LCB) is stopped by closing the corresponding inlet and outlet.

[0189] The feeding of the light current (LCA) to the adsorption column (B) may be carried out through one or more inlets located at different positions of the adsorption column (B). In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the light current (LCA) to the adsorption column (B) is carried out through an inlet located at the bottom of the adsorption column (B).

[0190] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the feeding of the light current (LCA) to the adsorption column (B) is carried out through two inlets, wherein the first inlet is located at the bottom of the adsorption column (B) and the second inlet is a lateral inlet in the adsorption column (B), with the condition that the feeding is performed either through the top inlet or the lateral inlet at a given time but not simultaneously through the two inlets.

[0191] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the light current (LCB) depleted in component XB is let out from the adsorption column (B) through an inlet located at the top of the adsorption column (B).

[0192] Recovery of gas component XA

[0193] In step d) of the process of the invention the gas component XA is collected.

[0194] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the gas component XA is recovered directly from the adsorption column (A) after the feeding step of the light current obtained in step a) to an adsorption column (A) (FL) through an inlet located at the top of the adsorption column (A) (see FIG. 1).

[0195] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the gas component XA is recovered directly from the adsorption column (B) after the feeding step of the light current (LCA) to an adsorption column (B) (RL) through an inlet located at the top of the adsorption column (B) (see FIG. 5).

[0196] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the gas component XA is recovered directly from the adsorption column (B) after the depressurization-compression through an inlet located at the top of the adsorption column (B) (see FIG. 5).

[0197] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the gas component XA is recovered directly from the adsorption column (B) after the purge step through an inlet located at the top of the adsorption column (B) (see FIG. 5).

[0198] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the gas component XA is recovered directly from the adsorption column (B) after the feeding step of the light current (LCA) to an adsorption column (B) (RL), after the depressurization-compression through an inlet located at the top of the adsorption column (B), and after the purge step, through an inlet located at the top of the adsorption column (B) (see FIG. 5).

[0199] Light current clean-up (RL) in adsorption column (A)

[0200] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the process of the invention further comprises a previous step before step b) which comprises introducing a stream of pure gas component XA into the adsorption column (A) while increasing the pressure and reducing the temperature of the adsorption column (A).

[0201] In one particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure of the adsorption column (A) is in the range 5 to 500 kPa. In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure of the adsorption column (A) is about 5 kPa, about 10 kPa, about 20 kPa, about 30 kPa, 40 kPa, about 50 kPa, about 60 kPa, about 70 kPa, about 80 kPa, about 90 kPa, about 100 kPa, about 150 kPa, about 200 kPa, about 250 kPa, about 300 kPa, about 350 kPa, about 400 kPa, about 450 kPa, or about 500 kPa.

[0202] According to one embodiment, optionally in combination with one or more features of the various embodiments described above or below, this step is carried out at a temperature from -20 to 80 °C, more particularly from -10 to 60 °C, depending on the mixture to be separated. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, this step is carried out at a temperature about -20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, or about 80 °C.

[0203] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, this step (RL) is carried out at substantially the same temperature of the next step (FL).

[0204] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the stream of pure gas component XA is introduced to adsorption column (A) through an inlet located at top of the adsorption column (A).

[0205] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, during the cooling step, the adsorption column (A) is cooled particularly by cooling column jackets and / or serpentine coils and / or finned tubes.

[0206] Cooling (ER) and regeneration by decompression (DR) in adsorption column (B)

[0207] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, when the process is carried out with an additional column (B), the RL step is carried out by simultaneously cooling (ER) the adsorption column (B) after the recycle-purge step. A particular embodiment of this configuration is shown in FIG. 5.

[0208] In one particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the adsorption column (B) during the cooling (ER) is in the range from -20 to 80 °C, more particularly from -10 to 60 °C. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the adsorption column (B) is about -20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, or about 80 °C.

[0209] According to another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the cooling (ER) of the adsorption column (B) is carried out at a pressure which is in the range from 100 to 6000 kPa. In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure of this step is about 100 kPa.

[0210] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, when the process is carried out with an additional column (B), step RL in column (A) is carried out by simultaneously decompressing (DR) the adsorption column (B) and recovering the gas component XB which has been adsorbed in the adsorption column (B), wherein the pressure is decreased to a desorption pressure which is below atmospheric pressure and is in the range from -90 to -50 kPa. A particular embodiment of this configuration is shown in FIG. 7.

[0211] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the recovery of the gas component XB from the adsorption column (B) is carried out through an inlet located at the top of the adsorption column (B).

[0212] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, during the recovery of the gas component XB, the adsorption column (B) is cooled particularly by cooling column jackets and / or serpentine coils and / or finned tubes.

[0213] Pressure reduction (DA) and compression (CA) in adsorption columns (A) and (B)

[0214] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, when the process is carried out with an additional column (B), step b) further comprises a depressurization-compression step after the feeding step of the light current (LCA) to a further adsorption column (B) (RL).

[0215] In one particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure of the adsorption column (A) is reduced until a value LP2 which is in the range from 100 to 3000 kPa, more particularly from 100 to 2000 kPa, and the pressure of the adsorption column (B) is increased until a value HP2 which is in the range from 100 to 6000 kPa, more particularly from 200 to 5000 kPa, with the condition that the pressure of the adsorption column (A) is lower than the pressure of the adsorption column (B).

[0216] In another particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure of the adsorption column (A) is reduced in CA until a value about is about 100 kPa, about 200 kPa, about 500 kPa, about 800 kPa, about 1000 kPa, about 1200 kPa, about 1500 kPa, about 1800 kPa, about 2000 kPa, about 2200 kPa, about 2500 kPa, about 2800 kPa, or about 3000 kPa.

[0217] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure of the adsorption column (B) is increased in DA until a value about 100 kPa, about 200 kPa, about 500 kPa, 800 kPa, about 1000 kPa, about 1200 kPa, about 1500 kPa, about 1800 kPa, about 2000 kPa, about 2200 kPa, about 2500 kPa, about 2800 kPa, about 3000 kPa, about 3200 kPa, about 3500 kPa, about 3800 kPa, about 4000 kPa, about 4200 kPa, about 4500 kPa, about 4800 kPa, about 5000 kPa, or about 6000 kPa.

[0218] According to one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the column (A) in the depressurization-compression step after the feeding step of the light current (LCA) to a further adsorption column (B) (RL) is from -20 to 80 °C, more particularly from -10 to 60 °C, depending on the mixture to be separated. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, temperature of the column (A) in the depressurization-compression step is about - 20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, or about 80 °C.

[0219] According to another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the column (B) in the depressurization-compression step after the feeding step of the light current (LCA) to a further adsorption column (B) (RL) is from -20 to 80 °C, more particularly from -10 to 60 °C, depending on the mixture to be separated. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, temperature of the column (B) in the depressurization-compression step is about - 20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, or about 80 °C.

[0220] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the column (A) in the in the depressurization-compression step is substantially the same temperature of the column (B). More particularly, the temperature of the columns (A) and (B) in the in the depressurizationcompression step is substantially the same as the temperature of the previous step (FL and RL).

[0221] In one particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the depressurization-compression step further comprises letting out from the adsorption column (B) a light current which contains component XA and is depleted in component XB and Xc. In this step the pressure of the adsorption column (A) is transferred to the adsorption column (B). More particularly, the stream of gas component XA is let out from adsorption column (B) through an inlet located at top of the adsorption column (B).

[0222] Heavy current recycle (RH) and purge step (PR) in adsorption columns (A) and (B)

[0223] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, when the process is carried out with an additional column (B), step b) further comprises a recycle-purge step after the depressurizationcompression step. This recycle-purge step comprises introducing a stream of pure gas component XB into the adsorption column (A), and simultaneously letting out from the adsorption column (B) a light current which contains component XA and is depleted in component XB and Xc. In this step the pressure of the adsorption column (A) is lower than the pressure of the adsorption column (B).

[0224] In one particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure of the adsorption column (A) is LP2 which is in the range from 100 to 3000 kPa, and the pressure of the adsorption column (B) is HP2 which is in the range from 100 to 6000 kPa, with the condition that the pressure of the adsorption column (A) is lower than the pressure of the adsorption column (B).

[0225] In one particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure of the adsorption column (1) is LP1 which is in the range from 100 to 3000 kPa, more particularly from 100 to 2000 kPa, and the pressure of the adsorption column (2) is HP1 which is in the range from 100 to 6000 kPa, more particularly from 200 to 5000 kPa, with the condition that the pressure of the adsorption column (1) is higher than the pressure of the adsorption column (2).

[0226] In another particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure of the adsorption column (A) is a value about is about 100 kPa, about 200 kPa, about 500 kPa, about 800 kPa, about 1000 kPa, about 1200 kPa, about 1500 kPa, about 1800 kPa, about 2000 kPa, about 2200 kPa, about 2500 kPa, about 2800 kPa, about 3000 kPa, about 3200 kPa, about 3500 kPa, about 3800 kPa, about 4000 kPa, about 4200 kPa, about 4500 kPa, about 4800 kPa, about 5000 kPa, or about 6000 kPa.

[0227] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure of the adsorption column (B) is a value about 100 kPa, about 200 kPa, about 500 kPa, 800 kPa, about 1000 kPa, about 1200 kPa, about 1500 kPa, about 1800 kPa, about 2000 kPa, about 2200 kPa, about 2500 kPa, about 2800 kPa or about 3000 kPa.

[0228] According to one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the column (A) in the recycle-purge step after the depressurization-compression step is from -20 to 80 °C, more particularly from -10 to 60°C, depending on the mixture to be separated. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, temperature of the column (A) in the recycle-purge step is about -20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, or about 80 °C.

[0229] According to another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the column (B) in the recycle-purge step after the depressurization-compression step is from -20 to 80 °C, more particularly from -10 to 60 °C, depending on the mixture to be separated. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, temperature of the column (B) in the recycle-purge step is about -20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, or about 80 °C.

[0230] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the column (A) in the recyclepurge step is substantially the same temperature of the column (B). More particularly, the temperature of the columns (A) and (B) in the in the recycle-purge step is substantially the same as the temperature of the previous step (DA and CA).

[0231] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the stream of pure gas component XB is introduced to adsorption column (A) through an inlet located at bottom of the adsorption column (A).

[0232] Regeneration by temperature and vacuum (TR / VR) and regeneration by temperature (TR) in adsorption column (A)

[0233] In step f) of the process of the invention the gas component XB which has been adsorbed in the adsorption column (A) is recovered from the said column by desorption. Step f) is carried out by increasing the temperature up to a desorption temperature Tdes2 which is in the range from 50 to 250 °C, and then decreasing the pressure to a desorption pressure PV2 which is below atmospheric pressure and is in the range from -100 to -10 kPa. Thus, the temperature of the adsorption column (A) in step f) is higher than the temperature of the adsorption column (A) in step b), and the pressure of the adsorption column (2) in step f) is lower than the temperature of the adsorption column (2) in step a).

[0234] In this step not only the gas component XB is recovered but also the adsorbent in the adsorption column (A) is regenerated and thus can be reused in other cycles of the process.

[0235] According to one embodiment, optionally in combination with one or more features of the various embodiments described above or below, step f) is carried out at a pressure PV2 in the range from -100 to -10 kPa, more particularly from -100 to -90 kPa, depending on the component to be recovered. In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure PV2 of step f) is about -100 kPa, about -90 kPa, about -80 kPa, about -70 kPa, about -60 kPa, about -50 kPa, about -40 kPa, about -30 kPa, about -20 kPa, or about -10 kPa.

[0236] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, step f) is carried out at a temperature Tdes2 from 50 to 250 °C, more particularly from 90 to 150 °C, depending on the component to be recovered. In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, step f) is carried out at a temperature about 50 °C, about 60 °C, about 70 °C, about 80 °C, about 90 °C, about 100 °C, about 110 °C, about 120 °C, about 130 °C, about 140 °C, about 150 °C, about 160 °C, about 170 °C, about 180 °C, about 190 °C, about 200 °C, about 210 °C, about 220 °C, about 230 °C, about 240 °C, or about 250 °C.

[0237] Alternatively, the gas component XB which has been adsorbed in the adsorption column (A) may be recovered from the said column by desorption by increasing the temperature up to a desorption temperature Tdesl which is in the range from 50 to 250 °C.

[0238] In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the recovery of the gas component XB from the adsorption column (A) is carried out through an inlet located at the bottom of the adsorption column (A). In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the recovery of the gas component XB from the adsorption column (A) is carried out through an inlet located at the top of the adsorption column (A).

[0239] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, during the recovery step (VR), the adsorption column (A) is heated particularly by heating column jackets and / or serpentine coils and / or finned tubes. When the multicomponent gas mixture comprises further gas components in addition to XA, XB, and Xc, the process of the invention further comprises step g) of recovering any other adsorbed gas component in addition to XA, XB, and Xc from the adsorption column in which it is adsorbed by increasing the temperature up to a desorption temperature which is in the range from 50 to 250 °C, and then decreasing the pressure to a desorption pressure which is below atmospheric pressure and is in the range from -100 to -10 kPa. The pressure and temperature conditions indicated for step f) apply to these additional steps.

[0240] Regeneration by cooling (ER) in adsorption column (B)

[0241] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, when the process is carried out with an additional column (B), step f) is carried out by simultaneously cooling the adsorption column (B) after the recycle-purge step.

[0242] In one particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the adsorption column (B) is in the range from -20 to 80 °C, more particularly from -10 to 60 °C, with the condition that the temperature of the adsorption column (B) is lower than the temperature of the adsorption column (A). In one more particular embodiment, optionally in combination with one or more features of the various embodiments described above or below, the temperature of the adsorption column (B) is about -20 °C, about -10 °C, about 0 °C, about 10 °C, about 20 °C, about 30 °C, about 40 °C, about 50 °C, about 60 °C, about 70 °C, or about 80 °C.

[0243] According to another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the cooling of the adsorption column (B) is carried out at substantially the same pressure in step f), which is in the range from 10 to 800 kPa. In one embodiment, optionally in combination with one or more features of the various embodiments described above or below, the cooling of the adsorption column (B) is carried out at a pressure which is about 10 kPa, about 50 kPa, about 100 kPa, about 150 kPa, about 200 kPa, about 250 kPa, about 300 kPa, about 350 kPa, about 400 kPa, about 450 kPa, about 500 kPa, about 550 kPa, about 600 kPa, about 650 kPa, about 700 kPa, about 750 kPa, or about 800 kPa.

[0244] In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, the pressure of this step is about 100 kPa. In another embodiment, optionally in combination with one or more features of the various embodiments described above or below, during the cooling step (ER), the adsorption column (B) is cooled particularly by cooling column jackets and / or serpentine coils and / or finned tubes.

[0245] In one example, the VTPSA process comprising steps a) to g) is performed with a multicomponent mixture of three gas components and two pairs of adsorption columns (i.e., 4 columns), as shown in Table 1. In the column pair I adsorbent column (1) goes through operations 1-5 and adsorbent column (2) executes operations 6-10. In column pair II adsorbent column (A) goes through operations 11-15 and adsorbent column (B) executes operations 16-20. Once the above step sequence is complete, the same sequence is repeated, changing column 1 to column 2 and column (A) to column (B). Thus, in column pair II adsorbent column (A) goes through operations 16-20, and adsorbent column (B) executes operations 11-15, and in the column pair I adsorbent column (1) goes through operations 6-10 and adsorbent column (2) executes operations 1-5.

[0246] Table 1

[0247] In another example, the VTPSA process comprising steps a) to g) is performed with a multicomponent mixture of three gas components and four pairs of adsorption columns (i.e., 8 columns), as shown in Table 2. In the column pair I adsorbent column (1) goes through operations 1-5 and adsorbent column (2) executes operations 6-10. In column pair II adsorbent column (3) goes through operations 8-10, 1-2 and adsorbent column (4) executes operations 3-7. In column pair III adsorbent column (A) goes through operations 11-15 and adsorbent column (B) executes operations 16-20. In column pair IV adsorbent column (C) goes through operations 18-20, 11-12 and adsorbent column (D) executes operations 13- 17. Once the above step sequence is complete, the same sequence is repeated, changing column 1 to column 2, column 3 to column 4, column (A) to column (B), and column (C) to column (D). Operations 1-20 are shown in Table 7. Table 2

[0248] In another example, when the VTPSA process comprising steps a) to g) is performed with a multicomponent mixture of three gas components and two pairs of adsorption columns (i.e., 4 columns), as shown in Tables 3 and 4. In the column pair I adsorbent column (1) goes through operations 1-28 and adsorbent column (2) executes operations 15-28, 1-14. In column pair II adsorbent column (A) goes through operations 29-38, 11-28, and adsorbent column (B) executes operations 15-38, 11-14. Once the above step sequence is complete, the same sequence is repeated, changing column 1 to column 2 and column (A) to column (B). Thus, in column pair II adsorbent column (A) goes through operations 15-38, 11-14, and adsorbent column (B) executes operations 29-38, 11-28, and in the column pair I adsorbent column (1) goes through operations 15-28, 1-14 and adsorbent column (2) executes operations 1-28. Operations 1-38 are shown in Table 7. Table s Table 4

[0249] In another example, the VTPSA process comprising steps a) to g) is performed with a multicomponent mixture of three gas components and four pairs of adsorption columns (i.e., 8 columns), as shown in Tables 5 and 6. in the column pair I adsorbent column (1) goes through operations 1-28 and adsorbent column (2) executes operations 15-28, 1-14. In column pair II adsorbent column (3) goes through operations 24-28, 1-23, and adsorbent column (4) executes operations 10-28, 1-9. In column pair III adsorbent column (A) goes through operations 29-38, 11-28, and adsorbent column (B) executes operations 15-38, 11- 14. In column pair IV adsorbent column (C) goes through operations 24-38, 11-23, and adsorbent column (D) executes operations 38, 11-37. Once the above step sequence is complete, the same sequence is repeated, changing column 1 to column 2, column 3 to column 4, column (A) to column (B), and column (C) to column (D). Operations 1-38 are shown in Table 7.

[0250] Table 5 Table 6

[0251] Table 7

[0252] Throughout the description and claims the word "comprise" and variations of the word, are not intended to exclude other technical features, additives, components, or steps. Furthermore, the word “comprise” encompasses the case of “consisting of”. Additional objects, advantages and features of the invention will become apparent to those skilled in the art upon examination of the description or may be learned by practice of the invention. The following examples and drawings are provided by way of illustration, and they are not intended to be limiting of the present invention. Reference signs related to drawings and placed in parentheses in a claim, are solely for attempting to increase the intelligibility of the claim, and shall not be construed as limiting the scope of the claim. Furthermore, the present invention covers all possible combinations of particular and preferred embodiments described herein.

[0253] Examples

[0254] Pilot-scale experiments were carried out. The initial gas mixture contained R-410 (50 w / w% R-125+ 50 w / w% R-32) + R-22, wherein the w / w % of R-125, R-32 and R-22 was 33.3%, 33.3%, and 33.4%, respectively. The system included 4 bed adsorbers (anodized aluminium, Height: 75 cm, diameter: 5 cm).

[0255] First pair of columns (1) and (2) contained Zeolite 5A (670 g per bed; bead diameter 2 mm; apparent density 660 g / L). Adsorption temperature: 40 °C, regeneration temperature: 120 °C, HP1 = 500 kPa, LP1 = 100 kPa; PV1 = 35 kPa, DA = 90 kPa.

[0256] Second pair of columns (A) and (B) contained Zeolite 4A (660 g per bed; bead diameter 2 mm; apparent density 650 g / L). Adsorption temperature: 50 °C, regeneration temperature: 100 °C, HP2 = 300 kPa, LP2 = 100 kPa; PV2 = 35 kPa, DA = 100 kPa.

[0257] Example 1

[0258] The separation of the ternary refrigerant gas mixture was carried out by separating first one of the three components in the first column pair I and then the other two components in the next column pair II as shown in FIG. 4 and FIG. 5. For the tested mixture, R-32 was first retained as heavy current and thus separated in the first column pair, and the resulting binary mixture R-125 + R-22 (light current in the first column pair) was separated in the second column pair; R-22 was retained as heavy current and R-125 was recovered as light current.

[0259] The following results were obtained:

[0260] Example 2

[0261] In this experiment the separation of the ternary refrigerant gas mixture was carried out according to configuration shown in FIG. 7, i.e., including alternate feeding of the mixture (lateral and top inlets). An analogue experiment was carried out wherein the mixture was fed from the bottom. The results are shown in the table below:

[0262] As can be seen when the alternate feeding was used higher yields and purities were consistently obtained.

[0263] Example 3

[0264] In this experiment the separation of the ternary refrigerant gas mixture was carried out according to configuration shown in FIG. 7. The recovery of the gases from a bottom inlet only was compared with the recovery from an alternate recovery from lateral and bottom inlets. The results are shown in the table below:

[0265] As can be observed when the alternate recovery was used the amount of purified gas per cycle increased. This allows shortening the process which has important advantages for a process to be implemented at industrial scale.

[0266] The above pilot-scale experiments show that the process of the invention allows the separation of refrigerant gas mixtures into the individual gases in good yields and purity without off-gas. For reasons of completeness, various aspects of the invention are set out in the following numbered clauses:

[0267] Clause 1. A vacuum temperature pressure swing adsorption (VTPSA) process for the recovery of individual gas components from a multicomponent gas mixture M without gas emissions into the atmosphere, wherein:

[0268] - the multicomponent gas mixture M comprises at least three gas components XA, XB, and Xc, and

[0269] - the process is carried out with a number of adsorption columns nc which is either nx-1 , or alternatively a multiple of nx-1 , wherein nxis the number of the gas components of the multicomponent gas mixture M, and comprises at least one cycle of the following steps: a) feeding a multicomponent gas mixture M to an adsorption column (1) at a suitable working pressure HP1 which is in the range from 100 to 6000 kPa, wherein the adsorption column (1) comprises an adsorbent that selectively retains a first gas component Xc, while letting out a light current (LC1) which contains components XA and XB and is depleted in component Xc; b) feeding the light current obtained in step a) to an adsorption column (A) at a suitable working pressure HP2 which is in the range from 100 to 6000 kPa, wherein the adsorption column (A) comprises an adsorbent that selectively retains a second gas component XB, while letting out a light current (LCA) which contains component XA and is depleted in components Xc and XB; c) repeating the process of step b) for each gas present in the multicomponent gas mixture M in addition to XA, XB, and Xc, if present, in further adsorption columns, wherein each of these further adsorption columns comprises an adsorbent that selectively retains one of the further gas components, while letting out a light current which is a gas stream depleted in the gas components already adsorbed in the adsorption columns, until the light current is enriched in component XA; d) collecting the third gas component XA; e) recovering the first gas component Xc from the adsorption column (1) by increasing the temperature up to a desorption temperature Tdesl which is in the range from 50 to 250 °C, and then decreasing the pressure to a desorption pressure PV1 which is below atmospheric pressure and is in the range from -100 to -10 kPa; f) recovering the second gas component XB from the adsorption column (A) by increasing the temperature up to a desorption temperature Tdes2 which is in the range from 50 to 250 °C, and then decreasing the pressure to a desorption pressure PV2 which is below atmospheric pressure and is in the range from -100 to -10 kPa; and g) recovering any other adsorbed gas component in addition to XA, XB, and Xc from the adsorption column in which it is adsorbed by increasing the temperature up to a desorption temperature which is in the range from 50 to 250 °C, and then decreasing the pressure to a desorption pressure which is below atmospheric pressure and is in the range from -100 to -10 kPa.

[0270] Clause 2. The process according to clause 1 , wherein the gas components of the multicomponent gas mixture M are refrigerant gases.

[0271] Clause 3. The process according to any of the clauses 1-2, wherein the feeding of the mixture M to the adsorption column (1) is carried out through two inlets, wherein the first inlet is located at the bottom of the adsorption column (1) and the second inlet is a lateral inlet in the adsorption column (1), with the condition that the feeding is performed either through the bottom inlet or the lateral inlet at a given time, but not simultaneously through the two inlets.

[0272] Clause 4. The process according to any of the clauses 1-3, wherein the feeding of the light current obtained in step a) to the adsorption column (A) is carried out through two inlets, wherein the first inlet is located at the bottom of the adsorption column (A) and the second inlet is a lateral inlet in the adsorption column (A), with the condition that the feeding is performed either through the bottom inlet or the lateral inlet at a given time, but not simultaneously through the two inlets.

[0273] Clause 5. The process according to any of the clauses 1-4, wherein the multicomponent gas mixture M consists of three gas components XA, XB, and Xc, and step a) further comprises feeding the light current (LC1) to a further adsorption column (2) at a suitable working pressure LP1 which is in the range from 100 to 3000 kPa, wherein the adsorption column (2) comprises an adsorbent that selectively retains further gas component Xc, while letting out a light current (LC2) which contains XA and XB, and is more depleted in Xc than the stream (LC1).

[0274] Clause 6. The process according to clause 5, wherein the feeding of the light current (LC1) to the adsorption column (2) is carried out through an inlet which is located at the top of the adsorption column (2).

[0275] Clause 7. The process according to any of the clauses 5-6, wherein step a) after the feeding step into the adsorption column (2) further comprises an equalization step by which pressure is transferred from the adsorption column (1) at a working pressure HP1 to the adsorption column (2) at a working pressure LP1 until the pressure values of the adsorption column (1) and the adsorption column (2) are substantially the same.

[0276] Clause 8. The process according to clause 7, wherein step a) after the equalization step, further comprises a depressurization-compression step by which a stream of pure gas component Xc is introduced into the adsorption column (1) while reducing the pressure of the adsorption column (1) to a value LP1 which is in the range from 100 to 3000 kPa, and simultaneously increasing the pressure of the adsorption column (2) until it has a working pressure HP1 which is in the range from 100 to 6000 kPa.

[0277] Clause 9. The process according to clause 8, wherein step e) is carried out by simultaneously cooling the adsorption column (2) after the depressurization-compression step to a temperature which is in the range from -20 to 80 °C, with the condition that the temperature of the adsorption column (2) is lower that the temperature of the adsorption column (1).

[0278] Clause 10. The process according to any of the clauses 5-9, wherein step b) further comprises feeding the light current (LCA) to a further adsorption column (B) at a suitable working pressure LP2 which is in the range from 100 to 3000 kPa, wherein the adsorption column (B) comprises an adsorbent that selectively retains further gas component XB, while letting out a light current (LCB) which contains component XA and is more depleted in components Xc and Xsthan the stream (LCA).

[0279] Clause 11. The process according to clause 10, wherein the feeding of the light current (LCA) to the adsorption column (B) is carried out through an inlet which is located at the bottom of the adsorption column (B).

[0280] Clause 12. The process according to any of the clauses 10-11 , wherein step b) further comprises a depressurization-compression step by which the pressure of the adsorption column (A) is reduced until a value LP2 which is in the range from 100 to 3000 kPa, and simultaneously increasing the pressure of the adsorption column (B) until a value HP2 which is in the range from 100 to 6000 kPa, while letting out from the adsorption column (B) a light current which contains component XA and is depleted in component XB and Xc. Clause 13. The process according to clause 12, wherein step b) after the depressurizationcompression step, further comprises a recycle-purge step by which a stream of pure gas component XB is introduced into the adsorption column (A), and simultaneously letting out from the adsorption column (B) a light current which contains component XA and is depleted in component XB and Xc.

[0281] Clause 14. The process according to clause 13, wherein step f) is carried out by simultaneously cooling the adsorption column (B) after the recycle-purge step to a temperature which is in the range from -20 to 80 °C, with the condition that the temperature of the adsorption column (B) is lower that the temperature of the adsorption column (A).

[0282] Clause 15. The process according to any of the clauses 1-14, wherein the adsorbents are selected from the group consisting of zeolites, activated carbons, metallic organic structures (MOF)s, silicalites, aluminosilicates, titanosilicates, germanosilicates, covalent-organic frameworks, carbon molecular sieves (CMSs), activated carbon, silica gel, and combinations thereof.

Claims

Claims1. A vacuum temperature pressure swing adsorption (VTPSA) process for the recovery of individual gas components from a multicomponent gas mixture M without gas emissions into the atmosphere, wherein:- the multicomponent gas mixture M comprises at least three gas components XA, XB, and Xc, and- the process is carried out with a number of adsorption columns nc which is either nx-1 , or alternatively a multiple of nx-1 , wherein nxis the number of the gas components of the multicomponent gas mixture M, and comprises at least one cycle of the following steps: a) feeding a multicomponent gas mixture M to an adsorption column (1) at a suitable working pressure HP1 which is in the range from 100 to 6000 kPa, wherein the adsorption column (1) comprises an adsorbent that selectively retains a first gas component Xc, while letting out a light current (LC1) which contains components XA and XB and is depleted in component Xc; b) feeding the light current obtained in step a) to an adsorption column (A) at a suitable working pressure HP2 which is in the range from 100 to 6000 kPa, wherein the adsorption column (A) comprises an adsorbent that selectively retains a second gas component XB, while letting out a light current (LCA) which contains component XA and is depleted in components Xc and XB; c) repeating the process of step b) for each gas present in the multicomponent gas mixture M in addition to XA, XB, and Xc, if present, in further adsorption columns, wherein each of these further adsorption columns comprises an adsorbent that selectively retains one of the further gas components, while letting out a light current which is a gas stream depleted in the gas components already adsorbed in the adsorption columns, until the light current is enriched in component XA; d) collecting the third gas component XA; e) recovering the first gas component Xc from the adsorption column (1) by increasing the temperature up to a desorption temperature Tdesl which is in the range from 50 to 250 °C, and then decreasing the pressure to a desorption pressure PV1 which is below atmospheric pressure and is in the range from -100 to -10 kPa; f) recovering the second gas component XB from the adsorption column (A) by increasing the temperature up to a desorption temperature Tdes2 which is in therange from 50 to 250 °C, and then decreasing the pressure to a desorption pressure PV2 which is below atmospheric pressure and is in the range from -100 to -10 kPa; and g) recovering any other adsorbed gas component in addition to XA, XB, and Xc from the adsorption column in which it is adsorbed by increasing the temperature up to a desorption temperature which is in the range from 50 to 250 °C, and then decreasing the pressure to a desorption pressure which is below atmospheric pressure and is in the range from -100 to -10 kPa; wherein the feeding of the mixture M to the adsorption column (1) is carried out through at least two inlets of the adsorption column (1), with the condition that the feeding is performed alternately through each of the inlets at a given time.

2. The process according to claim 1 , wherein the gas components of the multicomponent gas mixture M are refrigerant gases.

3. The process according to any of the claims 1-2, wherein the recovery of the gas components Xc from the adsorption column (1) and the recovery of the gas component XB from the adsorption column (A) is carried out through at least two inlets, with the condition that the feeding is performed alternately through each of the inlets at a given time.

4. The process according to any of the claims 1-3, wherein the feeding of the light current obtained in step a) to the adsorption column (A) is carried out through two inlets, wherein the first inlet is located at the bottom of the adsorption column (A) and the second inlet is a lateral inlet in the adsorption column (A), with the condition that the feeding is performed either through the bottom inlet or the lateral inlet at a given time, but not simultaneously through the two inlets.

5. The process according to any of the claims 1-4, wherein the multicomponent gas mixture M consists of three gas components XA, XB, and Xc, and step a) further comprises feeding the light current (LC1) to a further adsorption column (2) at a suitable working pressure LP1 which is in the range from 100 to 3000 kPa, wherein the adsorption column (2) comprises an adsorbent that selectively retains further gas component Xc, while letting out a light current (LC2) which contains XA and XB, and is more depleted in Xcthan the stream (LC1).

6. The process according to claim 5, wherein the feeding of the light current (LC1) to the adsorption column (2) is carried out through an inlet which is located at the top of the adsorption column (2).

7. The process according to any of the claims 5-6, wherein step a) after the feeding step into the adsorption column (2) further comprises an equalization step by which pressure is transferred from the adsorption column (1) at a working pressure HP1 to the adsorption column (2) at a working pressure LP1 until the pressure values of the adsorption column (1) and the adsorption column (2) are substantially the same.

8. The process according to claim 7, wherein step a) after the equalization step, further comprises a depressurization-compression step by which a stream of pure gas component Xc is introduced into the adsorption column (1) while reducing the pressure of the adsorption column (1) to a value LP1 which is in the range from 100 to 3000 kPa, and simultaneously increasing the pressure of the adsorption column (2) until it has a working pressure HP1 which is in the range from 100 to 6000 kPa.

9. The process according to claim 8, wherein step e) is carried out by simultaneously cooling the adsorption column (2) after the depressurization-compression step to a temperature which is in the range from -20 to 80 °C, with the condition that the temperature of the adsorption column (2) is lower that the temperature of the adsorption column (1).

10. The process according to any of the claims 5-9, wherein step b) further comprises feeding the light current (LCA) to a further adsorption column (B) at a suitable working pressure LP2 which is in the range from 100 to 3000 kPa, wherein the adsorption column (B) comprises an adsorbent that selectively retains further gas component XB, while letting out a light current (LCB) which contains component XA and is more depleted in components Xc and Xsthan the stream (LCA).11 . The process according to claim 10, wherein the feeding of the light current (LCA) to the adsorption column (B) is carried out through an inlet which is located at the bottom of the adsorption column (B).

12. The process according to any of the claims 10-11 , wherein step b) further comprises a depressurization-compression step by which the pressure of the adsorption column (A) is reduced until a value LP2 which is in the range from 100 to 3000 kPa, and simultaneously increasing the pressure of the adsorption column (B) until a value HP2 which is in the range from 100 to 6000 kPa, while letting out from the adsorption column (B) a light current which contains component XA and is depleted in component XB and Xc.

13. The process according to claim 12, wherein step b) after the depressurizationcompression step, further comprises a recycle-purge step by which a stream of pure gascomponent XB is introduced into the adsorption column (A), and simultaneously letting out from the adsorption column (B) a light current which contains component XA and is depleted in component XB and Xc.

14. The process according to claim 13, wherein step f) is carried out by simultaneously cooling the adsorption column (B) after the recycle-purge step to a temperature which is in the range from -20 to 80 °C, with the condition that the temperature of the adsorption column (B) is lower that the temperature of the adsorption column (A).

15. The process according to any of the claims 1-14, wherein the adsorbents are selected from the group consisting of zeolites, activated carbons, metallic organic structures (MOF)s, silicalites, aluminosilicates, titanosilicates, germanosilicates, covalent-organic frameworks, carbon molecular sieves (CMSs), activated carbon, silica gel, and combinations thereof.

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