Process for converting glycerol to propanol

Abstract

The present invention relates to a process for the production of propanol and isopropanol (bio-propanol), which are bio-components for gasoline. The present invention particularly relates to the conversion of bio-glycerol into bio-propanol and bio-isopropanol. In particular, the present invention relates to a process for the conversion of glycerol, in particular from renewable sources, into propanol, which comprises the following steps: a) hydrogenation of a glycerol phase with a Co-Cu-Mn-Mo based hydrogenation catalyst, obtaining an effluent containing water and an organic mixture comprising more than 40 wt% of a mixture of ethanol, 1-propanol and 2-propanol, the rest being unreacted propanediol and glycerol, and traces of ethylene glycol; b) separation of the mixture of ethanol, 1-propanol and 2-propanol from the other components in the effluent of step a) mainly by distillation; c) optionally, recycling all or part of the unreacted propanediol and glycerol from steps a) and / or b) to the hydrogenation step a).

Description

Technical Field

[0001] This invention relates to a method for producing propanol and isopropanol (biopropanol), which are biological components used in gasoline. The invention particularly relates to the conversion of bioglycerol into biopropanol and bioisopropanol. Background Technology

[0002] As is well known, emissions from burning fossil fuels include carbon dioxide (CO2), carbon monoxide (CO), and nitrogen oxides (NOx). x ), sulfur oxides (SO x Unburned hydrocarbons (HC), volatile organic compounds (VOCs), and particulate matter (PM) are the causes of environmental problems, such as ozone generation, the greenhouse effect (in the case of nitrogen oxides and carbon oxides), and acid rain (in the case of sulfur oxides and nitrogen oxides).

[0003] The continued increase in fuel consumption for transportation and growing sensitivity to the environment, along with increasingly stringent international legislative frameworks related to pollutant emissions and greenhouse gases, have led to a growing importance of methods that allow for the production of fuels from renewable resources (so-called biofuels).

[0004] In particular, with the accession to the Kyoto Protocol, the European Union issued a series of directives known as the "20120120 Package," which set out targets for mitigating global warming caused by human activities. A revised version of the RED Directive, known as the "ILUC Directive," encourages the use of "advanced" biofuels (i.e., those derived from municipal waste, algae, wastewater containing crude glycerol, lignocellulosic biomass, etc.).

[0005] Ethanol is a commonly used biofuel additive. However, using ethanol in gasoline blends is not without its drawbacks. Ethanol is hygroscopic, miscible with water over a wide temperature range, and immiscible with hydrocarbon mixtures. Furthermore, ethanol is characterized by its low calorific value and high latent heat of vaporization, which can cause cold-start problems. Additionally, ethanol can form azeotropes with light hydrocarbons, leading to increased volatility in ethanol-containing fuels.

[0006] In terms of ignition quality and calorific value, propanol has the same positive properties as ethanol, but they have a higher energy density (+12%), lower volatility, and a lower latent heat of vaporization (-8%). In principle, a good source of propanol could be glycerol.

[0007] Glycerin (glycerol or 1,2,3-propanetriol) is a polyol of great industrial value, which can be used as is or as an intermediate in the production of cosmetics, pharmaceuticals / health products, and animal feed. It is primarily obtained from triglycerides—the main components of animal and vegetable fats and oils—as a byproduct of saponification, hydrolysis, and transesterification reactions occurring in oleochemical plants and in biodiesel production. Specifically, the amount of glycerin obtained as a byproduct in biodiesel synthesis is estimated to be several million tons annually.

[0008] The literature describes several possibilities for stabilizing glycerol as a raw material, namely the hydrogenolysis of the CO bond, to simultaneously form propylene glycol, propanol, and propane, which are highly valuable for obtaining gasoline and biofuel additives. However, such methods are very complex because the reaction mechanism is strongly dependent on the reaction conditions and the catalyst used.

[0009] Typically, the reaction is carried out in the liquid phase using a batch system (autoclave) operating at high hydrogen pressure, employing a dilution mixture of glycerol and water to maximize the solubility of molecular hydrogen in the liquid phase. This facilitates mass transfer and avoids limitations associated with the low diffusivity (diffusion mode) of hydrogen.

[0010] U.S. Patent No. 5,616,817 discloses a method for producing 1,2-propanediol as a major component by catalytic hydrogenation of glycerol under high temperature and high pressure. This method means using glycerol with a water content of up to 20% by weight and a catalyst containing 40 to 70% by weight of cobalt, 10 to 20% by weight of copper, 0 to 10% by weight of manganese and 0 to 10% by weight of molybdenum, and the catalyst may also contain up to 10% by weight of inorganic polybasic acid and / or heteropolyacid.

[0011] The synthesis of 1,2-propanediol has been industrialized using various catalysts such as copper chromite. It is also well known that transition metal-based catalysts (especially Cu, Ni, and Co-based catalysts, such as Cu / SiO2, Cu / Al2O3, Ni Raney, and cobalt-aluminum alloys) promote this reaction at temperatures of 120–220 °C. These catalysts are generally selective for 1,2-propanediol because they do not promote the sequential reaction that forms propanol.

[0012] Furthermore, various catalysts based on single-metal noble metal nanoparticles have been tested, particularly Ru, Pt, and Rh on various supports (coal, TiO2, SiO2, Al2O3) for the production of propanol in a temperature range of 170–220 °C. Among these catalysts, Rh- and Ru-based catalysts have shown the most activity for hydrogenolysis, resulting in high glycerol conversion and the formation of a mixture rich in 1,2-propanediol and hydrogenolysis continuous reaction products (which have low yields and selectivity). However, noble metal catalysts without co-catalysts do not inherently offer a significant advantage over transition metal-based systems. To optimize catalytic activity and enhance continuous reactions, co-catalysts are typically added to noble metal-based catalysts.

[0013] It has been demonstrated that the addition of acidic co-catalysts (Amberlyst resin, sulfonated zirconium oxide, acidic zeolite, heteropolyacid) to Ru and Rh-based catalysts leads to improved catalytic performance in terms of glycerol conversion and 1,2-propanediol yield, while also increasing propanol formation to some extent under more demanding reaction conditions (i.e., higher temperatures and hydrogen pressures).

[0014] Related literature includes: Miyazawa, T., Koso, S., Kunimori, K., Tomishige, K., Development of a Ru / C Catalyst for Glycerol Hydrogenolysis in Combination with an Ion-Exchange Resin, Appl. Catal. A Gen. 2007, 318(3), 244-251; Balaraju, M., Rekha, V., Prasad, PSS, Devi, BLAP, Prasad, RBN, Lingaiah, N., Influence of Solid Acids as Co-Catalysts on Glycerol Hydrogenolysis to Propylene Glycolover Ru / C Catalysts, Appl. Catal. A Gen. 2009, 354(1-2), 82-87.

[0015] The addition of basic co-catalysts (LiOH, NaOH, CaO) is much less frequent and often leads to an increase in glycerol conversion, but also results in poorer PDO selectivity, promotes the breaking of C-C bonds, and forms ethylene glycol (EG) and lactate esters (Maris, EP, Ketchie, WC, Murayama, M., Davis, RJ, Glycerol Hydrogenolysis on Carbon-Supported PtRu and AuRu Bimetallic Catalysts, J. Catal. 2007, 251(2), 281-294; Maris, EP, Davis, RJ, Hydrogenolysis of Glycerol over Carbon-Supported Ru and Pt Catalysts, J. Catal. 2007, 249(2), 328-337). Lactate esters may originate from the Cannizzaro reaction, which occurs in the formation of 2-hydroxypropanal (obtained by dehydrogenation of 1,2-propanediol) with lactic acid and subsequent esterification.

[0016] Propanol can be produced using noble metal-based catalysts modified with dopants and promoters, particularly metal oxides (Groups 4-7) (Shinmi, Y., Koso, S., Kubota, T., Nakagawa, Y., Tomishige, K., Modification of Rh / SiO2 catalyst for the Hydrogenolysis of Glycerol in Water, Appl. Catal. BEnviron. 2010, 94(3-4), 318-326); however, the catalyst cost for this reaction is very high.

[0017] Dopants and promoters can alter the electronic properties of metal active phase nanoparticles, thereby changing the adsorption capacity of reagents. In fact, it is well known that the inclusion of rhenium oxide (ReOx) greatly increases the concentration of Rh (Shinmi, Y., Koso, S., Kubota, T., Nakagawa, Y., Tomishige, K., Modification of Rh / SiO2 catalyst for the Hydrogenolysis of Glycerol in Water, Appl. Catal. B Environ. 2010, 94(3-4), 318-326; Tomishige, K., Nakagawa, Y., Tamura, M., Selective Hydrogenolysis and Hydrogenation Using Metal Catalysts Directly Modified with Metal Oxide Species, Green Chem. 2017, 19(13), 2876-2924) and Pd (Ota, N., Tamura, M., Nakagawa, Y., Okumura, K., Tomishige, K., Performance, Structure, and Mechanism) of ReO x –Pd / CeO2Catalyst for Simultaneous Removal of Vicinal OH Groups with H2,ACSCatal.2016,6(5),3213-3226) and Ru(Tamura,M.,Amada,Y.,Liu,S.,Yuan,Z.,Nakagawa,Y.,Tomishige,K.,Promoting Effect of Ru on Ir-ReO x The catalytic activity of nanoparticles (SiO2 catalyst in Hydrogenolysis of Glycerol, J.Mol.Catal.A Chem.2014,388-389,177-187) promoted the selective formation of 1,3-propanediol.

[0018] Although propylene glycol is a good starting material in some industrial applications, it is not suitable as an additive for biofuels, as reported in the European standard EN 228 for gasoline.

[0019] Therefore, there is a need for a method to convert glycerol into propanol with high conversion rate and selectivity and low propylene glycol content. Summary of the Invention

[0020] One object of the present invention is a hydrogenation method for obtaining propanol from glycerol, particularly from bio-glycerol and bio-isopropanol, as defined in the appended claims, the statements of which are considered part of this specification to satisfy the requirement of adequacy of disclosure.

[0021] In particular, the present invention relates to a method for converting glycerol, especially glycerol from renewable resources, into propanol, the method comprising the following steps:

[0022] a) Hydrogenating the glycerol phase with a Co-Cu-Mn-Mo-based hydrogenation catalyst to obtain an effluent containing a mixture of water and an organic mixture comprising more than 40 wt% of a mixture of ethanol, 1-propanol and 2-propanol, the remainder being unreacted propylene glycol and glycerol, and trace amounts of ethylene glycol.

[0023] b) Separate the mixture of ethanol, 1-propanol and 2-propanol from the other components in the effluent of step a) by primary distillation;

[0024] c) Optionally, all or part of the unreacted propylene glycol and glycerol from steps a) and / or b) are recycled to hydrogenation step a).

[0025] Another object of the present invention is an apparatus for initiating the method of the present invention, comprising:

[0026] - At least one hydrogenation reactor filled with a hydrogenation catalyst;

[0027] - At least one first distillation column is configured to separate a mixture of propanol, isopropanol, ethanol and water from the at least one hydrogenation reactor from other reactor effluent components, wherein the heaviest components, primarily 1,2-propanediol, 1,3-propanediol and ethylene glycol, as well as unreacted glycerol, are removed from the bottom.

[0028] - At least one second distillation column is configured for extractive distillation to separate water and ethylene glycol as an entrainer solvent from the bottom and to separate high-purity propanol, isopropanol and ethanol from the top.

[0029] - Optionally, at least one third distillation column is configured to separate ethylene glycol from the bottom and water from the top.

[0030] Further features and advantages of the invention will become clear from the following detailed description. Attached Figure Description

[0031] Figure 1 A flowchart of a simplified embodiment of an apparatus for glycerol hydrogenation according to the present invention is shown;

[0032] Figure 2 A flowchart of another embodiment of the apparatus according to the invention for glycerol hydrogenation and subsequent recovery of alcohol fractions is shown;

[0033] Figure 3 A flowchart of a third embodiment of the hydrogenation section of an apparatus for glycerol hydrogenation according to the present invention is shown;

[0034] Figure 4 It shows Figure 3 Flowchart of the distillation section of the equipment;

[0035] Figure 5 The invention is shown Figure 3 A flowchart of a variant of the equipment used for glycerol hydrogenation;

[0036] Figure 6 It shows Figure 4 Flowchart of equipment variations. Detailed Implementation

[0037] For the purposes of this specification and the following claims, unless otherwise stated, the definition of a numerical range always includes the endpoint values.

[0038] In the description of embodiments of the invention, the use of the terms "comprising" and "containing" indicates the described options, such as steps of a method or process, or components of a product or apparatus, and does not necessarily include all. However, it is important to note that this application also relates to embodiments in which the term "comprising" in relation to the described options (e.g., steps of a method or apparatus) must be interpreted as "consistently consisting of" or "component of," even if this is not explicitly stated.

[0039] For the purposes of this invention, the term "fuel" refers to "diesel or gasoline".

[0040] For the purposes of this invention, the term "diesel fuel" refers to a mixture primarily composed of hydrocarbons (such as paraffins, aromatics, and cycloalkanes) typically having 9-30 carbon atoms, which can be used as fuel. Typically, diesel fuel is distilled at temperatures between 180°C and 450°C. The diesel fuel may be selected from diesel fuel conforming to the specifications for transport diesel fuel in standard EN 590:2009, or diesel fuel not conforming to those specifications. The density of the diesel fuel at 15°C, as determined according to standard EN ISO 12185:1996 / C1:2001, may be 780 kg / m³. 3 Up to 845kg / m 3 800kg / m 3 Up to 840kg / m 3According to standard EN ISO 2719:2002, the flash point of the diesel fuel may be greater than or equal to 55°C, preferably greater than or equal to 65°C. The cetane number of the diesel fuel, determined according to standard EN ISO 5165:1998 or standard ASTM 06890:2008, may be greater than or equal to 47, preferably greater than or equal to 51. Diesel fuel suitable for the purposes of this invention can be any known diesel fuel, possibly derived from diesel fuel mixtures of different sources and compositions. Preferably, these diesel fuel mixtures have a sulfur content of 200 to 1 mg / kg, even more preferably 10 to 1 mg / kg. Typical diesel fuel can be a middle fraction, preferably having a boiling point of 180-380°C, such as diesel fuel from primary distillation, diesel fuel from vacuum distillation, diesel fuel from thermal cracking or catalytic cracking, such as desulfurized diesel fuel from fluidized catalytic cracking, light cycle oil (LCO), diesel fuel from Fischer-Tropsch process or synthetic sources. The term "diesel" also includes so-called green diesel and biodiesel blends, as well as mixtures with conventional refinery diesel.

[0041] For the purposes of this specification and the following claims, the term "gasoline" or "gasoline mixture" refers to a mixture primarily comprising hydrocarbons (e.g., alkanes, aromatics, alkenes, and cycloalkanes) typically having 3-12 carbon atoms, which can be used as a fuel, characterized by an end point (ASTM 086) not exceeding 250°C, preferably not exceeding 210°C, wherein the end point is the temperature at which 100% by volume of the hydrocarbon mixture is distilled. The density of the gasoline may be 700 to 800 kg / m³. 3 The preferred value is 720 to 775 kg / m³. 3 The gasoline available is gasoline and its mixtures derived from catalytic processes, preferably fluid catalytic cracking (FCC) processes, reforming processes, and as is known in the art. Preferably, these gasoline mixtures have a sulfur content of 50 to 0.1 mg / kg, even more preferably 10 to 0.5 mg / kg. Unleaded gasoline is particularly preferred, which contains a mixture of hydrocarbons with a boiling point over a relatively narrow temperature range at atmospheric pressure, for example, between 25°C and 225°C. Some gasolines may contain oxygenated compounds, such as alcohols (e.g., ethanol, propanol) or ethers (e.g., methyl tert-butyl ether, MTBE). Gasoline may also contain various additives, such as detergents, antifreeze, demulsifiers, corrosion inhibitors, dyes, anti-deposition agents, and octane boosters.

[0042] For the purposes of this specification and the following claims, “derived from renewable resources” (e.g., “glycerol derived from renewable resources”) means a compound that is not derived from fossil resources such as crude oil, carbon, natural gas, oil sands, etc., but is derived directly from plant biomass, algae, microorganisms, or from the treatment of more complex compounds derived from said plant biomass, algae, and microorganisms.

[0043] For the purposes of this specification and the appended claims, unless otherwise stated, the term propanol refers to all isomers of propanol, namely 1-propanol, 2-propanol, or isomers of both mixed in any proportion.

[0044] For the purposes of this specification and the following claims, the term "single-pass conversion" refers to the conversion rate of the starting material (i.e., glycerol) calculated from the input to the output of the hydrogenation reactor.

[0045] According to a first aspect, the present invention relates to a method for converting glycerol, particularly glycerol from renewable sources (hereinafter referred to as "bioglycerol"), into propanol, which can be used as a fuel component in biofuel mixtures.

[0046] The method of the present invention includes the following steps:

[0047] a) Hydrogenating the glycerol phase with a Co-Cu-Mn-Mo-based hydrogenation catalyst to obtain an effluent containing a mixture of water and an organic mixture comprising more than 40 wt% of a mixture of ethanol, 1-propanol and 2-propanol, the remainder being unreacted propylene glycol and glycerol, and trace amounts of ethylene glycol.

[0048] b) Separate the mixture of ethanol, 1-propanol and 2-propanol from the other components in the effluent of step a) by distillation;

[0049] c) Optionally, all or part of the unreacted propylene glycol and glycerol from steps a) and / or b) are recycled to hydrogenation step a).

[0050] The organic mixture in the effluent of step a) preferably contains:

[0051] - At least 35% by weight, more preferably at least 40% by weight of 1-propanol;

[0052] - At least 5% by weight, more preferably at least 8% by weight, of a mixture of ethanol and 2-propanol;

[0053] - Less than 45% by weight, more preferably less than 37% by weight of 1,2-propanediol;

[0054] - Less than 16% by weight, more preferably less than 7% by weight of unreacted glycerol.

[0055] Depending on the reaction conditions, the effluent mixture may also contain less than 8% by weight, more preferably less than 5% by weight, a mixture of other alcohol components (ethylene glycol, 1,3-propanediol, acetone alcohol, trace amounts of other alcohols) and acetone.

[0056] Glycerin can be any type of glycerin, preferably or including bio-glycerin. The glycerin phase can consist of glycerin in substantially pure form, or of a glycerin / water mixture containing up to 25% by weight, preferably up to 20% by weight, more preferably up to 15% by weight of water.

[0057] Essentially pure glycerol is preferably commercially available with a purity grade of at least 98%.

[0058] Alternatively, when using glycerol in a substantially pure form, if the glycerol originates from the transesterification of triglycerides, the glycerol can be pre-purified to remove any excess salt and water that may be present. Crude glycerol can undergo a pre-purification treatment to obtain glycerol with the desired purity. This purification can be carried out, for example, by a method comprising two steps:

[0059] - In the first step, the salt contained in the crude glycerol produced from FAME is removed by treatment on an acid exchange resin such as Amberlyst 15 or Amberlyst 36, preferably at a temperature of 0°C to 60°C, or even more preferably at 15°C to 30°C, under atmospheric pressure.

[0060] - In the second step, impurities present in the crude glycerol, mainly water and a small amount of methanol, are removed by fractionation until a glycerol content of at least 95-96% is obtained.

[0061] Further details regarding glycerol purification are described, for example, in "PERP Report Glycerin conversion to propylene glycol 06 / 0784, March 2008". The glycerol obtained from the above steps can be used in the method according to the invention without any further purification.

[0062] Step a) can be carried out in glycerol as is or in the presence of a solvent. Possible solvents that can be used are, for example, the same reaction products propanol and propylene glycol, preferably in the same proportions required for the hydrogenation of the reaction products. Another solvent or co-solvent can be water, but it constitutes the reaction products and is always present in the mixture discharged from step (a).

[0063] The hydrogenation catalyst is preferably a supportless hydrogenation catalyst containing, in its calcined, non-reducing state, 40-70% by weight, preferably 64-68% by weight, cobalt (in the form of Co3O4), 13-22% by weight, preferably 18-20.5% by weight, copper (as CuO), 3-8% by weight, preferably 6.6-7.8% by weight, manganese (as Mn3O4), 0.1-5% by weight, preferably 2.5-3.5% by weight, phosphorus (as H3PO4), 0.5-5% by weight, preferably 3-4% by weight, molybdenum (as MoO3), and 0-10% by weight, alkali metal oxides.

[0064] Hydrogenation is carried out at a temperature of 220°C to 270°C, preferably 240°C to 260°C, more preferably about 250°C, and at a pressure of 130 to 170 bar, preferably 140 to 160 bar, more preferably about 150 bar.

[0065] An important parameter in this process is LHSV. LHSV (Liquid Hourly Space Velocity) (by mass) is defined as the ratio of the weight of the fresh glycerol phase feed (kg / hr) to the weight of the catalyst (kg)—preferably 0.15 to 2 hr. -1 More preferably 0.15 to 1.0 hr -1 Even more preferably 0.2 to 0.7hr -1 The optimal value is 0.23 to 0.5 hr. -1 .

[0066] The hydrogenation catalyst can be obtained according to the method described in US 5,107,018, which is incorporated herein by reference.

[0067] According to this method, salts of cobalt, copper, and manganese, along with phosphoric acid, are mixed in an aqueous solution and precipitated as metal salts in a two-stage precipitation process. This two-stage precipitation involves first adjusting the pH of the solution to 8 by adding an alkali metal carbonate solution at a temperature of 30°C to 70°C, and then adjusting the pH to less than 7.5 by adding another metal salt solution. The precipitate is collected by filtration or centrifugation and then calcined at a temperature of 400°C to 600°C to form the corresponding oxides. The recovered material is cooled after calcination, washed if necessary, impregnated with molybdate, and then fixed to the material (mass) by acid treatment with molybdate. The material is then shaped, dried, and activated by hydrogen reduction.

[0068] In step a), the conversion rate of glycerol to the product in a single pass is greater than 70%, preferably greater than 80%, and more preferably greater than 90%.

[0069] The method according to the present invention can be performed using conventional pressure equipment known to those skilled in the art.

[0070] More specifically, step a) can be performed as follows.

[0071] Glycerol is first compressed and heated to reach the operating conditions for the reaction. The heating process can be carried out by recovering heat from the reactor effluent.

[0072] The reactor is a trickle bed, consisting of a single or multiple catalytic beds alternating by gas quenching, filled with a catalyst as defined above.

[0073] A gaseous feed stream, primarily containing hydrogen, is mixed with the feed stream before entering the reactor. The mixed stream then enters the reactor and comes into contact with the catalyst. Here, the conversion of glycerol to 1,2-propanediol is achieved, followed by the conversion of the latter to 1-propanol and isopropanol. Ethanol, 1,3-propanediol, ethylene glycol, trace amounts of acetone and acetone, and small amounts of gases such as methane, propane, and ethane are produced as byproducts of hydrogenation. Water is also a byproduct.

[0074] Downstream of the reactor and upstream of step b), a series of flash evaporation units with reduced temperature and pressure are provided to separate the gaseous products from the liquid.

[0075] Since hydrogenation is highly exothermic, a rise in temperature is expected within the catalytic volume. To keep the temperature within acceptable ranges for catalyst stability, according to some embodiments, a portion of the flash liquid effluent from the flash unit is recycled and mixed with the feed. Another embodiment provides for controlling the exothermic reaction by introducing a cold gas into the catalytic volume, which can be divided into two or more beds with intermediate quenching.

[0076] On the other hand, the flash gas stream leaving the aforementioned flash unit provides a gas circulation loop and provides the task of preheating the hydrogen and the feed from the upstream step b).

[0077] Because the waste gas containing hydrogen may cause problems in the distillation section, a series of additional flash evaporation units (e.g., three flash evaporation units) are placed downstream of the reactor to separate the waste gas containing excess hydrogen, methane, and trace amounts of propane and ethane from the liquid phase.

[0078] Step b) involves separating ethanol, 1-propanol, and 2-propanol (alcohol phase) from other components (diol phase) in the effluent of step a) by distillation, comprising the following stages:

[0079] i) Distilling the effluent by top separation of the glycol phase and unreacted glycerol from the alcohol phase and water; ii) Distilling the alcohol phase and water from stage i) by top separation of water from the alcohol phase using ethylene glycol as an entrainer.

[0080] iii) Optionally, ethylene glycol and water from stage ii) are distilled by bottom recovery of ethylene glycol.

[0081] Step b) can be performed at atmospheric pressure, under slight overpressure, or under vacuum.

[0082] In stage ii), the ratio between the ethylene glycol feed rate (in Kmol / hr) and the alcohol / water feed rate (in Kmol / hr) is 2 to 3.5. When calculated based on the feed rate in kg / hr, this ratio is 0.5 to 6.5.

[0083] Distillation can be carried out by fractionation, continuously or discontinuously, preferably continuously, using, for example, fractionation columns of suitable size. Each of stages i), ii), and iii) of separation step (b) can be carried out by two or more distillation columns placed in series with each other. The boiling points and phase diagrams of different compounds and their mixtures are well known and suitable for separation as needed.

[0084] Based on what is known in the prior art, the tower used can be made of stainless steel or other suitable materials.

[0085] According to a preferred embodiment of the invention, the unreacted glycerol separated in step (b) is recycled together with ethylene glycol and propylene glycol to step (a).

[0086] In a preferred embodiment, the distillation section consists of three distillation columns.

[0087] The first distillation column separates the mixture of propanol, isopropanol, ethanol, and water from the effluent components of the other reactors. The heaviest components, mainly 1,2-propanediol, 1,3-propanediol, and ethylene glycol, as well as unreacted glycerol, are removed from the bottom.

[0088] The second column is an extractive distillation unit, which separates water and alcohol from the azeotropic mixture. For this purpose, the column requires ethylene glycol as a solvent capable of carrying away water. As a result, high-purity propanol, isopropanol, and ethanol can be recovered from the top, while the solvent and water are removed from the lowest stage and can be sent to the entrainer recovery column.

[0089] The third column regenerates ethylene glycol, which is then recycled from the bottom of the column to the extraction unit, while water is separated at the top.

[0090] For the use of 1-propanol as a component of gasoline mixtures, the presence of ethanol in the mixture does not represent any disadvantage and it can be successfully used as a component of gasoline without any further separation.

[0091] When performing the recycling step c), the combined feed ratio (CFR, given by the ratio between the combined fresh feed and the recycled feed / fresh feed) is preferably less than 20 and greater than 5. A CFR below 5 will not adequately control the temperature in the hydrogenation reactor (the reaction is exothermic), while a CFR above 20 will mean a significant increase in plant CAPex and OPex costs.

[0092] Example 1

[0093] Figure 1 A simplified process flow at the laboratory scale is shown.

[0094] 183 g of hydrogenation catalyst C as defined above is charged into a 1” fixed-bed reactor 100. A glycerol-water mixture (feed A) is fed for an extended period of time along with hydrogen (150 Nl / hr) at a feed rate of 80 g / hr (of which 68 g / h is glycerol). Mixture A is fed into the fixed-bed reactor 100 at 240 °C and 150 bar via pump 103 and heat exchanger 102.

[0095] Based on fresh feed, the liquid hourly space velocity (LSHV) is 0.44 h⁻¹. -1 A liquid recirculation rate of 1.8 kg / hr and a combined feed ratio (CFR) of 22.5 were applied.

[0096] Two separation containers 104 and 105 are located downstream of reactor 100 to remove gaseous products (waste gas), including unreacted hydrogen, from reactor effluent B.

[0097] The final product mixture E is recovered from the bottom of the second separation vessel 105. A portion of this product mixture is recycled (feed stream F) back into the feed stream A.

[0098] The composition (wt%) of liquid effluent B from reactor 100 is reported as follows based on analysis:

[0099] • Aqueous mixture: 37%

[0100] Water: 100%

[0101] • Organic mixture: 73%

[0102] ο Ethanol + Isopropanol = 8.0%

[0103] o-Propanol = 40.0%

[0104] 1,2-Propane glycol = 35.0%

[0105] οEthylene glycol + 1,3-propylene glycol = 2.0%

[0106] 0.0% glycerol = 15.0%.

[0107] Example 2

[0108] Figure 2 This describes an apparatus for processing 200-500 cc / h of 85wt% glycerol using 1.44 kg of catalyst C loaded in a tubular reactor 200 with an inner diameter of 55 mm. The feed stream A is mixed with pure hydrogen before entering the reactor 200. The apparatus includes a mixing vessel 201 to contain the combined feed and recirculated streams F1 and F2 (see below) made from fresh glycerol / water fed into the reactor. Feed stream A is circulated by pump 202 and heated by heat exchanger 210.

[0109] Reactor effluent B passes through a first separation vessel 203, which operates at high temperature, to separate the waste gas. The gaseous phase from 203 is sent to another separation vessel 204, while being pre-cooled in a heat exchanger 211 to recover some of the evaporated products so as not to be lost in the waste gas. A portion of the product leaving the bottom of the first separation vessel 203 is recycled to a mixing vessel 201, while the remaining product, along with the liquid phase from separation vessel 204, is sent to a low-pressure distillation column 208. In distillation column 208, the product fractions (propanol and ethanol) and water (feed stream E1) are separated at the top of the column. If complete conversion of the reagents is required, the bottom feed stream of distillation column 208, containing unreacted glycerol and propylene glycol, can be recycled to the mixing vessel 201.

[0110] Feed stream E1 is fed to two additional separation vessels 205 and 206 for further separation of waste gas from the liquid phase (feed stream G). Feed stream G, containing product and water, is sent to a second distillation column 209, which uses ethylene glycol (EG) as an entrainer for product dehydration. In distillation column 209, the product fractions (propanol and ethanol) are separated at the top of the column, with a water content below 2500 ppmw, and are recovered after final waste gas removal through a fourth separation vessel 207. The ethylene glycol and water feed streams from the bottom are ultimately regenerated offline by heating the mixture.

[0111] The basic LHSV of this device is approximately 0.3h. -1 The inlet temperature of the hydrogenation reactor 200 is 250°C. The reactor pressure is 150 bar. The table below summarizes the main parameters of the equipment during standard testing:

[0112] Reactor inlet T [°C] 250 Catalyst loading [kg] 1.44 Reactor inlet P [bar] 150 Fresh feed [kg / h] 0.41 Material flow F1 feed [kg / h] 2.415 Feed rate F2 [kg / h] 0.4 <![CDATA[LHSV[h -1 ]]]> 0.28 Combined Feed Ratio (CFR) by weight 7.9 Hydrogen [NL / h] 450

[0113] The composition (wt%) of reactor liquid effluent B, based on analysis, is reported as follows:

[0114] • Aqueous mixture: 40%

[0115] Water: 100%

[0116] • Organic mixture: 60%

[0117] ο Ethanol + Isopropanol = 9.0%

[0118] o-Propanol = 42.0%

[0119] 1,2-Propane glycol = 41.0%

[0120] οEthylene glycol + 1,3-propylene glycol = 2.0%

[0121] 0.0% glycerol = 6.0%

[0122] The reactor effluent B is then fed into the distillation section. The final product stream exiting the top of column 209 has the following composition:

[0123] Ethanol = 8.0%

[0124] Isopropanol = 10.0%

[0125] • n-Propanol = 82%

[0126] Water: ≤2500ppmw.

[0127] Figure 3 and 4 Another example of equipment used in an industrial process for carrying out the present invention is illustrated.

[0128] Specifically, Figure 3 Part of the equipment used to carry out the hydrogenation reaction (step a) is shown, while Figure 4 A specific part of the equipment used for performing separation step b) is shown.

[0129] Fresh glycerol feed (pure or mixed with water) is conveyed in mixing vessel 301, where it is mixed with a recycled feed stream F containing ethylene glycol + propylene glycol (from distillation column 401, see [link]). Figure 4 Mixing. The feed stream A is compressed and heated (via heat exchanger 302) under hydrogenation conditions (see description below), and hydrogen stream D is added, which is also heated and compressed at the required temperature and pressure.

[0130] Feed stream A is fed to hydrogenation reactor 300, which is filled with hydrogenation catalyst C. Effluent B is cooled in heat exchanger 303 and then sent to first separation vessel 304, where liquid effluent B1 is recovered from the bottom and partially recycled (feed stream F') back to feed stream A. The gaseous product, along with some stripped liquid product, is sent to second separation vessel 305, which continues to separate the gaseous product (top effluent) from the liquid product (bottom effluent B2).

[0131] Liquid product streams B1 and B2 are sent to the third separation vessel 306, and then to the fourth separation vessel 307, where the gaseous product and the liquid product (stream B) are completely separated. Stream B is then sent to the distillation separation step b).

[0132] The gaseous products (mainly containing hydrogen) recovered from the second separation vessel 305 are partially recycled and added to the fresh hydrogen feed sent to the reactor 300, while the gaseous products from the third and fourth separation vessels 306 and 307 and the remaining gaseous effluent from the second separation vessel 305 are recovered as waste gas.

[0133] refer to Figure 4 Step b) of the separation by distillation includes a first distillation column 401 into which the liquid product (stream B) from step a) is fed. In distillation column 401, the alcohol fraction and water (stream E) are separated at the top, while a mixture of ethylene glycol, propylene glycol, and unreacted glycerol is recovered from the bottom and at least partially recycled to the hydrogenation reactor 300 (stream F).

[0134] The alcohol fraction containing propanol and ethanol, along with water (stream E), is partially recycled to the top of distillation column 401. The remaining portion, after being heated by heat exchanger 405, preferably a shell-and-tube heat exchanger, is fed into the middle section of the second distillation column 402. At the top of the same column 402, ethylene glycol is fed as an entrainer (stream G). The second distillation column 402 separates the dehydrated alcohol fraction at the top (stream H) and separates the mixture of ethylene glycol and water at the bottom (stream I), which is then fed into the third distillation column 403.

[0135] The third distillation column 403 is a recovery column for ethylene glycol. In column 403, water is distilled off, and the essentially anhydrous ethylene glycol is recovered at the bottom (stream G2), and it is added to fresh ethylene glycol (stream G1) to form stream G as the feed to the second distillation column 402. Since stream G2 leaves the third column 403 at a high temperature (approximately 200°C), the collected stream G must be cooled in heat exchanger 405' before being fed into the second column 402.

[0136] The product stream B from hydrogenation step a) is preferably heated at 140-150°C before being fed into the first distillation column 401. This column is preferably an 11-stage column and is operated under slight overpressure, for example, about 1.5 atmospheres.

[0137] The second distillation column 402 is preferably a 60-stage column. Feed stream E is preferably fed at a temperature of 140°C-160°C or about 150°C, while ethylene glycol (feed stream G) is fed at a temperature selected from room temperature to 150°C. Water absorption is maximized when operating at temperatures from room temperature to 40°C. On the other hand, a temperature range of 120-140°C is preferred if improved heat recovery and energy saving are desired.

[0138] The alcohol fraction (stream H) recovered at the top of the second distillation column 402 typically contains less than 1 mol%, preferably less than 0.5 mol%, of a mixture of ethylene glycol and propylene glycol, and less than 3000 ppm, preferably less than 2600 ppm, of water.

[0139] In one example, the alcohol fraction of feed stream H has the following composition:

[0140] - 1-Propanol 27.4 mol%

[0141] - 2-Propanol 46.6 mol%

[0142] - Ethanol / Methanol 24.7 mol%.

[0143] The third distillation column 403 can be a 20-stage column, in which the ethylene glycol / water mixture is fed in the middle section at a temperature of 155°C to 170°C.

[0144] The above equipment is just an example and can be modified according to specific needs.

[0145] For example, more than one hydrogenation reactor 300 may be provided. If at least two hydrogenation reactors 300 are provided, they may be connected in parallel or in series.

[0146] The number of separation vessels 304, 305, 306, and 307 can be calculated based on the reaction conditions, equipment size, and productivity.

[0147] When the glycerol conversion rate is very high or when required by other operations, the recirculation stream F can be omitted.

[0148] Figure 5 Describes the combination Figure 3 The described equipment variant. This process design is combined with the above. Figure 3 The process is the same as described above, but a second hydrogenation reactor 300', similar to reactor 200, exists, serving as a finisher for the reaction. This finishing reactor 300' contains a catalyst with a mass 3 to 5 times lower than that of the main reactor 300. The finishing reactor 300' can receive feed stream F", which is a portion of feed stream F from the bottom of the first distillation column 401 (see [link to documentation]). Figure 4 The product is rich in active substances, namely propylene glycol and residual glycerol. In the refining reactor 300', complete conversion of glycerol and near-complete conversion of propylene glycol can be achieved. The effluent from the hydrorefining reactor 300' is then sent to the first distillation column 401 to separate the alcohol fraction and water formed during the reaction.

[0149] The advantage of an alternative configuration with a secondary reactor is the possibility of conducting the reaction on a highly concentrated feed stream, thus removing or reducing the amount of unreacted material recycled back to the main reactor. The disadvantage is the cost associated with installing another reactor, which includes designing a more efficient method to control the exothermic reaction (i.e., gas quenching), which acts as a diluent and helps control temperature rise when operating with an anhydrous inlet feed stream.

[0150] Figure 6 Described Figure 4 The variation shown is a distillation section provided to improve equipment consumption and the amount of entrainer required for alcohol purification.

[0151] The distillation section includes a first distillation column 401 into which the liquid product (stream B) from step a) is fed. In distillation column 401, the alcohol fraction and water (stream E) are separated at the top, while a mixture of ethylene glycol, propylene glycol, and unreacted glycerol is recovered from the bottom and at least partially recycled to the hydrogenation reactor 300 (stream F).

[0152] The alcohol fraction containing propanol and ethanol, along with water (stream E), is partially recycled to the top of distillation column 401. The remainder is fed into liquid-liquid extraction vessel 410, where stream E is contacted with a processing solvent preferably selected from toluene, hexane, cyclohexane, methylcyclohexane, heptane, isooctane, and DIPE. Water is discharged from the bottom of vessel 410, while the alcohol fraction and processing solvent (stream H') are separated at the top of vessel 410.

[0153] Feed stream H' is fed into the second distillation column 402. At the top of the same column 402, an entrainer (feed stream G'), such as ethylene glycol, is fed. The second distillation column 402 (extractive distillation column) separates the substantially anhydrous alcohol fraction (mainly ethanol, 1-propanol, and 2-propanol, feed stream H) at the top and a mixture of entrainer and treatment solvent (feed stream I') at the bottom, which is then fed into the third distillation column 403.

[0154] The third distillation column 403 separates the entrainer (stream G') at the bottom and then feeds it into the second distillation column 402, while the processing solvent is recovered at the top of column 403 and fed into the liquid-liquid extraction vessel 410 (stream S).

[0155] The above variants minimize the heat and energy consumption during the distillation stage.

Claims

1. A method for converting glycerol to propanol, the method comprising the following steps: a) Hydrogenating the glycerol phase with a Co-Cu-Mn-Mo-based hydrogenation catalyst to obtain an effluent containing a mixture of water and an organic mixture comprising more than 40 wt% of a mixture of ethanol, 1-propanol and 2-propanol, the remainder being unreacted propylene glycol and glycerol, and trace amounts of ethylene glycol; step a) is carried out at a temperature of 220°C to 270°C and a pressure of 130 to 170 bar; b) The mixture of ethanol, 1-propanol and 2-propanol in the effluent of step a) is separated from other components mainly by distillation; c) Optionally, all or part of the unreacted propylene glycol and glycerol from steps a) and / or b) are recycled to hydrogenation step a), wherein the LHSV, by mass, is defined as the ratio of the weight of the fresh glycerol phase feed in kg / hr to the weight of the catalyst in kg, which is 0.15 to 2 hr. -1 .

2. The method according to claim 1, wherein the organic mixture in the effluent of step a) comprises: - At least 35% by weight of 1-propanol; - A mixture of at least 5% by weight of ethanol and 2-propanol; - Less than 45% by weight of 1,2-propanediol; - Less than 16% by weight of unreacted glycerol.

3. The method according to claim 1 or 2, wherein the glycerol phase consists of glycerol in substantially pure form or a glycerol / water mixture containing up to 25% by weight of water.

4. The method according to claim 1 or 2, wherein the hydrogenation catalyst is a supportless hydrogenation catalyst containing, in its calcined, non-reducing state, 40-70 wt% cobalt in the form of Co3O4, 13-22 wt% copper as Cu, 3-8 wt% manganese as Mn3O4, 0.1-5 wt% phosphorus as H3PO4, 0.5-5 wt% molybdenum as MoO3, and 0-10 wt% alkali metal oxides.

5. The method according to claim 1 or 2, wherein hydrogenation is carried out at a temperature of 240°C to 260°C and a pressure of 140 to 160 bar.

6. The method according to claim 1 or 2, wherein the LHSV is 0.15 to 1.0 hr by mass. -1 .

7. The method according to claim 1 or 2, wherein in step a), the conversion rate of glycerol to the product in a single pass is greater than 70%.

8. The method according to claim 1 or 2, wherein step b) of separating the ethanol, 1-propanol, and 2-propanol as alcohol phases from the other components as diol phases in the effluent of step a) by distillation comprises the following stages: i) Distilling the effluent by top separation of the alcohol phase and water from the diol phase and unreacted glycerol; ii) Distillation of the alcohol phase and water from stage i) by top separation of the alcohol phase and water using extractive distillation with ethylene glycol as an entrainer; iii) Optionally, the ethylene glycol and water from stage ii) are distilled by bottom recovery of ethylene glycol.

9. The method of claim 8, wherein in stage ii), the ratio between the ethylene glycol feed rate in kg / hr and the alcohol / water feed rate in kg / hr is 2 to 3.5; or the ratio between the ethylene glycol feed rate in kg / hr and the alcohol / water feed rate in kg / hr is 0.5 to 6.

5.

10. The method according to claim 8, wherein, When performing recycling step c), the combined feed ratio is less than 20 and greater than 5, whereby the combined feed ratio is the ratio between the combined fresh feed and the recycled feed / fresh feed.

11. The method of claim 8, wherein step b) is performed at atmospheric pressure, or under slight overpressure or vacuum.

12. The method according to claim 1, wherein step b) of separating the ethanol, 1-propanol, and 2-propanol as alcohol phases from the other components as diol phases in the effluent of step a) by distillation comprises the following stages: i) Distilling the effluent by top separation of the alcohol phase and water from the diol phase and unreacted glycerol; ii) Liquid-liquid extraction of the alcohol phase and water with a treatment solvent, followed by top separation of the alcohol fraction and treatment solvent from the water; iii) The alcohol phase and the treatment solvent from stage ii) are distilled by top separation of the alcohol phase and the treatment solvent using extractive distillation with an entrainer; iv) Optionally, the entrainer and treatment solvent from stage iii) are distilled by top recovery of the treatment solvent.

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