A system and a process for the generation of syngas

Abstract

The present disclosure relates to a system and a process for the generation of syngas. The system and the process of the present disclosure utilizes a reverse water gas shift reaction and carbon dioxide capture process to reduce the amount of carbon dioxide and water in the product stream. The captured carbon dioxide is then recycled to the reverse water gas shift reactor. The system and the process of the present disclosure reduces the amount of recycle molar ratio, thereby eliminate the need of larger equipments.

Description

[0001] A SYSTEM AND A PROCESS FOR THE GENERATION OF SYNGAS

[0002] FIELD

[0003] The present disclosure relates to a field of fuel generation.

[0004] DEFINITIONS

[0005] As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used, indicate otherwise.

[0006] Conversion per pass: The term “conversion per pass” refers to the amount of reactant converted to a product when fed to a one reactor volume. Generally, in any chemical process, conversion is calculated in terms of ‘mole’.

[0007] Recycle molar ratio: The term “recycle molar ratio” refers to the amount of recovered feed that is recycled to the main feed, when measured in moles.

[0008] Syngas: The term “syngas” also known as “synthesis gas” refers to a mixture of hydrogen and carbon monoxide that is used to produce fuels and chemicals.

[0009] Time on stream (TOS) evaluation: The term “time on stream evaluation” in chemical processes refers to the duration that a chemical reaction operates continuously without interruption over the time. This metric is crucial for assessing the stability and efficiency of catalytic reactions, particularly in processes involving catalysts, where performance can degrade overtime due to factors such as deactivation or coke formation.

[0010] Weight hourly space velocity: The term “weight hourly space velocity” refers to the ratio of the mass flow rate of a feed to the mass of a catalyst in a reactor.

[0011] Yield per pass: The term “yield per pass” refers to the amount of product produced when the reactant is fed to a one reactor volume. Yield per pass may also be defined as mole of product formed per initial mole of reactant fed.BACKGROUND

[0012] The background information herein below relates to the present disclosure but is not necessarily prior art.

[0013] The conventional technologies for the generation of syngas primarily focusses on natural gas as a feed gas which is subjected to the processes such as partial oxidation, catalytic steam methane reforming, two-step reforming, auto-thermal reforming, and heat exchange reforming. The reactor can be chosen based on the requirement and the characteristic of the reactor. The steam methane reforming does not require oxygen and high temperature, but it produces much higher hydrogen to carbon monoxide ratio (1.2 to 2.8) than needed. The partial oxidation process is carried out in the absence of catalyst and thus lowers carbon dioxide content. However, it requires oxygen and high operating temperature causing soot formation that is hard to handle and produces hydrogen to carbon monoxide molar ratio in the range of 1.0 to 1.6. The autothermal reforming process, known as endothermic syngas reforming reactions is carried out by the internal heat obtained by oxidation of a portion of the feed hydrocarbons, has the most favorable hydrogen to carbon monoxide molar ratio (1.9 to 2.6), but it needs oxygen to proceed and has limited commercial experience. While recycling carbon dioxide, and removing hydrogen would decrease ratio, however increasing steam in the product gas would yield opposite effect. The heat exchange for reforming can use compact equipment and introduces flexibility to application. However, in some cases, it must be coupled with other syngas producing techniques to achieve the desired outcome. All the syngas reaction pathway offers specific hydrogen to carbon monoxide molar ratio.

[0014] The catalytic conversion of carbon dioxide has attracted a great deal of attention over a last few decades. However, conversion of carbon dioxide requires a large amount of additional eneigy due to its chemically non-reactive nature. Hence, in any given reaction involving carbon dioxide a high energy is required to induce reactivity. Due to the chemical stability of carbon dioxide, the reaction to convert it to the more reactive molecule is through reverse water gas shift reaction as given by Eq. (1).Eq. (1)

[0015] CO2 + H2 = CO + H2O AH25C = +41 kJ / mol

[0016] Eq. (2)

[0017] CO2 + 4H2= CH4+ 2H2O AH25C = -165 kJ / mol

[0018] The reverse water gas shift reaction is thermodynamically favorable at high temperature due to its endothermic nature and hence, the conversion of carbon dioxide is favored at high reaction temperatures (>500 °C). For example, approximately about 55% conversion can be achieved at -540 °C, while about 80% conversion can be achieved at -950 °C. Increasing the hydrogen to carbon dioxide molar ratio maximizes the carbon dioxide conversion and favours the reverse water gas shift reaction. For this reason, when the reaction is carried out at lower temperatures, the equilibrium will increasingly favour the water gas shift (reverse of Eq. (1)) reaction and subsequently the Sabatier reaction, also known as methanation (Eq. (2)) reaction, as they are exothermic and most prominent side reactions under these conditions.

[0019] Therefore, there is felt a need to provide an efficient system and a process for the generation of syngas to mitigate the above drawbacks or at least provide a useful alternative.

[0020] OBJECTS

[0021] Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:

[0022] It is an object of the present disclosure to ameliorate one or more problems of the background or to at least provide a useful alternative.

[0023] Another object of the present disclosure is to provide a process for the generation of syngas.

[0024] Still another object of the present disclosure is to provide a process for the generation of syngas that is simple and eneigy efficient.

[0025] Yet another object of the present disclosure is to provide a process for the generation of syngas that reduces the amounts of undesired compounds such as carbon dioxide, methane, water andthe like.

[0026] Still another object of the present disclosure is to provide a system for the generation of syngas.

[0027] Yet another object of the present disclosure is to provide a system for the generation of syngas that is simple and eneigy efficient.

[0028] Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.

[0029] SUMMARY

[0030] The present disclosure provides a process for the generation of syngas, the process comprising the following steps: a first stream containing a predetermined molar ratio of hydrogen and carbon dioxide is compressed to a predetermined pressure in at least one compressor to obtain a pressurized stream; the pressurized stream is pre-heated in a first heat exchanger to a first predetermined temperature followed by heating in a furnace to a second predetermined temperature to obtain a hot stream; the hot stream is fed to a first reactor at a predetermined weight hourly space velocity, at the second predetermined temperature and at the predetermined pressure in the presence of a catalyst to obtain a second stream comprising carbon monoxide, water, unconverted carbon dioxide and unconverted hydrogen; the second stream is separated to obtain a third stream comprising the syngas, and a fourth stream containing carbon dioxide and water; and the fourth stream containing carbon dioxide and water is cooled in a second heat exchanger and fed to a gas-liquid separator to obtain a water stream and a fifth stream containing carbon dioxide.

[0031] In accordance with the present disclosure, the second stream is separated by using a carbon dioxide capture process. The carbon dioxide capture process comprises the following steps: the second stream is cooled to a temperature in the range of 70 °C to 90 °C in sequentially arranged the first heat exchanger and a third heat exchanger to obtain a cooled stream; the cooled stream is fed to a second reactor containing a sorbent and treating at a temperature in the range of 70 °C to 90 °C and at a pressure in the range of 1.5 bar to 3.5 bar for a time period in the range of5 minutes to 15 minutes to obtain a rich capture media having adsorbed unconverted carbon dioxide and water on the sorbent, and the third stream comprising the syngas; the rich capture media is heated in a capture media heater to a temperature in the range of 90 °C to 120 °C; the rich capture media is regenerated in a third reactor at a temperature in the range of 130 °C to 150 °C for a time period in the range of 2 minutes to 8 minutes to obtain a lean capture media containing the sorbent devoid of carbon dioxide and water, and the fourth stream containing carbon dioxide and water. The lean capture media is pre-cooled in a capture media cooler and recycled to the second reactor.

[0032] In accordance with the present disclosure, the fifth stream containing carbon dioxide is recycled to the first reactor through the compressor to form a mixed feed stream.

[0033] In accordance with the present disclosure, the predetermined molar ratio of hydrogen to carbon dioxide is in the range of 1 : 1 to 4: 1 ; the predetermined pressure is in the range of 2.5 bar to 5 bar; the first predetermined temperature is in the range of 300 °C to 450 °C; the second predetermined temperature is in the range of 550 °C to 650 °C; and the predetermined weight hourly space velocity of feeding the catalyst is in the range of 2 hr"1to 6 hr"1.

[0034] In accordance with the present disclosure, the catalyst is an alkali carbonate impregnated alumina based support, and the alkali carbonate in the catalyst is present in an amount in the range of 5 mass% to 20 mass%; the alkali carbonate is selected from dipotassium carbonate (K2CO3) and disodium carbonate (Na2COs); and the alumina based support is selected from the group consisting of gamma-alumina, silica-alumina, boehmite, pseudo-boehmite and gibbsite.

[0035] In accordance with the present disclosure, the catalyst is 10 mass% dipotassium carbonate impregnated on gamma-alumina support (K2CO3 / Y-AI2O3).

[0036] In accordance with the present disclosure, the sorbent is an alkali carbonate impregnated alumina based support, and the alkali carbonate in the sorbent is present in an amount in the range of 25 mass% to 35 mass% with respect to the total mass of the sorbent; the alkali carbonate is selected from dipotassium carbonate (K2CO3) and disodium carbonate (Na2CC>3);and the alumina based support is selected from the group consisting of gamma-alumina, silica-alumina, boehmite, pseudo-boehmite and gibbsite.

[0037] In an exemplary embodiment, the sorbent is 30 mass% of dipotassium carbonate impregnated in on gamma-alumina support (K2CO3 / y-AhCh) with respect to the total mass of the sorbent. In accordance with the present disclosure, the furnace is heated by combusting natural gas (NG) in air to emit flue gas.

[0038] In accordance with the present disclosure, the fourth stream is cooled in a second heat exchanger to a temperature in the range of 40 °C to 60 °C.

[0039] In accordance with the present disclosure, the gas-liquid separator operates at a temperature in the range of 40 °C to 60 °C and at a pressure is in the range of 1 bar to 3 bar.

[0040] In accordance with the present disclosure, the third stream of syngas comprises 60 mol% to 70 mol% of hydrogen, 30 mol% to 40 mol% of carbon monoxide, 3 mol% to 4 mol% of carbon dioxide, and 0.25 mol%to 0.5 mol% of water.

[0041] The present disclosure provides a system for the generation of syngas, the system comprises:

[0042] (i) a compressor configured to receive a first stream comprising a predetermined molar ratio of hydrogen to carbon dioxide, and further configured to compress the first stream to a predetermined pressure to obtain a pressurized stream;

[0043] (ii) a first heat exchanger configured to receive the pressurized stream and further configured to pre-heat the pressurized stream to a first predetermined temperature to obtain a pre-heated stream;

[0044] (iii) a furnace configured to receive the pre-heated stream and further configured to heat the pre-heated stream to a second predetermined temperature to obtain a hot and pressurized stream;

[0045] (iv) a first reactor containing a catalyst, configured to receive the hot and pressurized first stream at a predetermined weight hourly space velocity, and further configured to carry out areverse water gas shift reaction (rWGS) at the second predetermined temperature and at the predetermined pressure to obtain a second stream comprising carbon monoxide, water, unconverted carbon dioxide and unconverted hydrogen;

[0046] (v) a carbon capture unit configured to receive the second stream and further configured to separate the second stream into a third stream comprising the syngas and a fourth stream containing carbon dioxide and water;

[0047] (vi) a second heat exchanger configured to receive the fourth stream and further configured to cool the fourth stream; and

[0048] (vii) a gas-liquid separator configured to receive the cooled fourth stream and further configured to separate the cooled fourth stream into a water stream and a fifth stream containing carbon dioxide.

[0049] In accordance with the present disclosure, the carbon capture unit comprises:

[0050] (i) at least one third heat exchanger configured to receive the second stream and further configured to cool the second stream to a temperature in the range of 70 °C to 90 °C;

[0051] (ii) a second reactor containing a sorbent, configured to receive the cooled second stream and further configured to treat the cooled second stream at a temperature in the range of 70 °C to 90 °C and at a pressure in the range of 1.5 bar to 2.5 bar for a time period in the range of 5 minutes to 15 minutes to obtain a rich capture media having adsorbed unconverted carbon dioxide and water on the sorbent; and the third stream comprising syngas;

[0052] (iii) a capture media heater configured to receive the rich capture media and further configured to heat the rich capture media to a temperature in the range of 90 °C to 120 °C;

[0053] (iv) a third reactor configured to receive the heated rich capture media and further configured to regenerate the rich capture media at a temperature in the range of 130 °C to 150 °C for a time period in the range of 2 minutes to 8 minutes to obtain a lean capture media containing the sorbent devoid of carbon dioxide and water; and the fourth stream containing carbon dioxideand water; and

[0054] (v) a capture media cooler configured to receive the lean capture media and further configured to cool the lean capture media and recycle to the second reactor.

[0055] In accordance with the present disclosure, the compressor is further configured to receive and recycle the fifth stream containing carbon dioxide.

[0056] In accordance with the present disclosure, the second reactor is equipped with a cool water circulation unit to maintain the temperature within the second reactor.

[0057] In accordance with the present disclosure, the third reactor is equipped with a low pressure steam circulation unit to maintain the temperature within the third reactor.

[0058] In accordance with the present disclosure, the system further comprises a benefit unit, the benefit unit is configured to receive the flue gas emitted from the furnace and further configured to heat water to generate high pressure steam.

[0059] In accordance with the present disclosure, the third heat exchanger, the capture media heater, and the capture media cooler utilizes a thermic fluid as a heat exchange media.

[0060] BRIEF DESCRIPTION OF ACCOMPANYING DRAWING

[0061] The present disclosure will now be described with the help of the accompanying drawing, in which:

[0062] Fig. 1 illustrates a schematic diagram for the system (1000) for the generation of syngas in accordance with the present disclosure;

[0063] Fig.2 illustrates a block flow diagram of the process for the generation of syngas in accordance with the present disclosure;

[0064] Fig.3 illustrates a block flow diagram of an indirect process for the methanol production, which utilizes the syngas generated in accordance with the present disclosure;Fig. 4 illustrates a block flow diagram of a direct process for the methanol production (conventional process);

[0065] Fig. 5 illustrates a time-on-stream evaluation results for 10 mass% K2CO3 / Y-AI2O3 catalyst depicting variation in carbon dioxide conversion and carbon monoxide yield as a function of time in accordance with the process of the present disclosure; and

[0066] Fig. 6 illustrates performance of reverse water gas shift reaction: variation of carbon dioxide conversion and carbon monoxide yield with reaction time for different weighted hour space velocity (WHSV) for 10 mass% K2CO3 / AI2O3 catalyst at 550 °C and 3 bar.

[0067] LIST OF REFERENCE NUMERALS

[0068] 1000 - system for generation of syngas

[0069] 10 - first stream comprising hydrogen and carbon monoxide

[0070] 12 - a mixture of natural gas (NG) and air

[0071] 14 - second stream comprising carbon monoxide, water, unconverted carbon dioxide and unconverted hydrogen

[0072] 16 - flue gas (FG)

[0073] 18 - high pressure (HP) steam

[0074] 20 - third stream containing syngas

[0075] 22 - rich capture media

[0076] 24 - lean capture media

[0077] 26 - make up thermic fluid

[0078] 28 - fourth stream containing carbon dioxide and water

[0079] 30 - water stream

[0080] 32 - fifth stream containing carbon dioxide

[0081] 34 - mixed feed stream

[0082] 102 - compressor

[0083] 104 - first heat exchanger

[0084] 106 - furnace108 - first reactor

[0085] 200 - carbon dioxide capture unit

[0086] 202 - third heat exchanger

[0087] 204 - second reactor

[0088] 206 - capture media heater

[0089] 208 - third reactor

[0090] 210 - capture media cooler

[0091] 212 - cooling water circulation unit

[0092] 214 - low pressure steam circulation unit

[0093] 216 - fourth heat exchanger / thermic fluid cooler

[0094] 302 - second heat exchanger

[0095] 304 - gas liquid separator

[0096] 400 - benefit unit

[0097] DETAILED DESCRIPTION

[0098] The present disclosure relates to a field of fuel generation.

[0099] Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.

[0100] Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.

[0101] The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may beintended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises”, “comprising," “including,” and “having,” are open-ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units, and / or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0102] As used herein, the term "and / or" includes any combinations of one or more of the associated listed elements.

[0103] The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer, or section from another component, region, layer, or section. Terms such as first, second, third, etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.

[0104] The catalytic conversion of carbon dioxide to methanol has attracted a great deal of attention over a last few decades. However, conversion of carbon dioxide requires a large amount of additional energy due to its chemically non-reactive nature. Hence, in any given reaction involving carbon dioxide a price needs be paid to induce reactivity. So, there is a need to provide an efficient process for conversion of carbon dioxide to carbon monoxide.

[0105] In an aspect, the present disclosure provides a system (1000) for the generation of syngas. The system is now explained with reference to Fig. 1. The system comprises a compressor (102), a first heat exchanger (104), a furnace (106), a first reactor (108), a carbon capture unit (200), a second heat exchanger (302) and a gas-liquid separator (304).

[0106] The compressor (102) is configured to receive a first stream (10) comprising a predetermined molar ratio of hydrogen to carbon dioxide, and further configured to compress the first stream (10) to a predetermined pressure to obtain a pressurized stream.

[0107] In accordance with the present disclosure, the predetermined molar ratio of hydrogen to carbon dioxide is in the range of 1: 1 to 4: 1. In an exemplary embodiment, the predetermined molarratio of hydrogen to carbon dioxide is 2.7:1.

[0108] In accordance with the present disclosure, the predetermined pressure is in the range of 2.5 bar to 5 bar. In an exemplary embodiment, the predetermined pressure is 3 bar. In another exemplary embodiment, the predetermined pressure is 3.45 bar.

[0109] The first heat exchanger (104) is configured to receive the pressurized stream and further configured to pre-heat the pressurized stream to a first predetermined temperature to obtain a pre-heated stream.

[0110] In accordance with the present disclosure, the first predetermined temperature is in the range of 300 °C to 450 °C. In an exemplary embodiment, the first predetermined temperature is 400 °C.

[0111] The furnace (106) is configured to receive the pre-heated stream and further configured to heat the pre-heated stream to a second predetermined temperature to obtain a hot and pressurized stream.

[0112] In accordance with the present disclosure, the second predetermined temperature is in the range of 550 °C to 650 °C. In an embodiment, the second predetermined temperature is 575 °C. In an exemplary embodiment, the second predetermined temperature is 600 °C.

[0113] The first reactor (108) containing a catalyst, configured to receive the hot and pressurized first stream at a predetermined weight hourly space velocity, and further configured to carry out a reverse water gas shift reaction (rWGS) at the second predetermined temperature and at the predetermined pressure to obtain a second stream (14) comprising carbon monoxide, water, unconverted carbon dioxide and unconverted hydrogen.

[0114] In accordance with the present disclosure, the predetermined weight hourly space velocity of feeding the catalyst is in the range of 2 hr"1to 6 hr"1. In an exemplary embodiment, the weight hourly space velocity of feeding the catalyst is 3 hr"1. In another exemplary embodiment, the weight hourly space velocity of feeding the catalyst is 4 hr"1. In still another exemplary embodiment, the weight hourly space velocity is 6 hr"1.The carbon capture unit (200) configured to receive the second stream (14) and further configured to separate the second stream (14) into a third stream (20) comprising the syngas and a fourth stream (28) containing carbon dioxide and water.

[0115] The second heat exchanger (302) configured to receive the fourth stream (28) and further configured to cool the fourth stream. In an embodiment, the second heat exchanger (302) cools the fourth stream to a temperature in the range of 40 °C to 50 °C.

[0116] The gas-liquid separator (304) configured to receive the cooled fourth stream and further configured to separate the cooled fourth stream into a water stream (30) and a fifth stream (32) containing carbon dioxide.

[0117] In accordance with the present disclosure, the carbon capture unit (200) comprises at least one third heat exchanger (202), a second reactor (204), a capture media heater (206), a third reactor (208), and a capture media cooler (210).

[0118] The at least one third heat exchanger (202) configured to receive the second stream (14) and further configured to cool the second stream (14) to a temperature in the range of 70 °C to 90 °C.

[0119] The second reactor (204) containing a sorbent, configured to receive the cooled second stream (14) and further configured to treat the cooled second stream at a temperature in the range of 70 °C to 90 °C and at a pressure in the range of 1.5 bar to 2.5 bar for a time period in the range of 5 minutes to 15 minutes to obtain a rich capture media having adsorbed unconverted carbon dioxide and water on the sorbent, and the third stream (20) comprising syngas.

[0120] The capture media heater (206) configured to receive the rich capture media (22) and further configured to heat the rich capture media to a temperature in the range of 90 °C to 120 °C.

[0121] The third reactor (208) configured to receive the heated rich capture media and further configured to regenerate the rich capture media at a temperature in the range of 130 °C to 150 °C for a time period in the range of 2 minutes to 8 minutes to obtain a lean capture media (24) containing the sorbent devoid of carbon dioxide and water, and the fourth stream (28)containing carbon dioxide and water.

[0122] The capture media cooler (210) configured to receive the lean capture media (24) and further configured to cool the lean capture media and recycle to the second reactor (204).

[0123] In accordance with the present disclosure, the compressor (102) is further configured to receive and recycle the fifth stream (32) containing carbon dioxide.

[0124] In accordance with the present disclosure, the second reactor (204) is equipped with a cool water circulation unit (212) to maintain the temperature within the second reactor (204).

[0125] In accordance with the present disclosure, the third reactor (208) is equipped with a low pressure steam circulation unit (214) to maintain the temperature within the third reactor (208).

[0126] In accordance with the present disclosure, the system further comprises a benefit unit (400), the benefit unit (400) is configured to receive the flue gas (16) emitted from the furnace (106) and further configured to heat water to generate high pressure steam (18).

[0127] In accordance with the present disclosure, the third heat exchanger (202), the capture media heater (206), and the capture media cooler (210) utilizes a thermic fluid as a heat exchange media.

[0128] In another aspect, the present disclosure provides a process for the generation of syngas. The process is described in detail with the help of drawings given in Fig. 1 to 4.

[0129] With reference to Fig. 1, a first stream (10) containing a predetermined molar ratio of hydrogen to carbon dioxide is compressed in at least one compressor (102) to a predetermined pressure to obtain a pressurized stream.

[0130] In accordance with the present disclosure, carbon dioxide in the first stream is derived from stationary sources such as power plant, refinery, chemical plant, cement plant, bio-gas plant or from non-stationary sources such as air, and the like. Hydrogen in the first stream is derived from biomass gasification, hydrogen manufacturing unit in refinery / chemical plant, electrolyzer and the like which are a stationary source. In accordance with the presentdisclosure, the first stream has a temperature in the range of 30 °C to 45 °C.

[0131] In accordance with the present disclosure, the predetermined molar ratio of hydrogen to carbon dioxide is in the range of 1: 1 to 4: 1. In an exemplary embodiment, the predetermined molar ratio of hydrogen to carbon dioxide is 2.7:1.

[0132] In accordance with the present disclosure, the predetermined pressure is in the range of 2.5 bar to 5 bar. In an exemplary embodiment, the predetermined pressure is 3.45 bar.

[0133] In an embodiment, the compressor is a multi-stage compressor to maintain the pressure in the range of 2.5 bar to 5 bar to satisfy the pressure drop downstream. This is required to meet pressure drop requirement due to the presence of other downstream units that are working at some pressure ratings.

[0134] The pressurized stream is pre-heated in a first heat exchanger (104) to a first predetermined temperature followed by heating in a furnace (106) to a second predetermined temperature to obtain a hot stream.

[0135] In accordance with the present disclosure, the first predetermined temperature is in the range of 300 °C to 450 °C. In an exemplary embodiment, the first predetermined temperature is 400 °C.

[0136] In accordance with the present disclosure, the second predetermined temperature is in the range of 550 °C to 650 °C. In an exemplary embodiment, the second predetermined temperature is 600 °C.

[0137] In accordance with the present disclosure, the furnace heats the pressurized stream to a temperature in the range of 550 °C to 600 °C by combusting natural gas (NG) in air (12) to emit flue gas (16). The furnace with NG firing provides necessary heat for endothermic reverse water gas shift reaction (AH298K = +41 kJ / mol). The heat quality of the flue gas from the furnace can be utilized for the generation high pressure (HP) steam in the benefit unit (400) comprising steam generation unit.In the next step, the hot stream is fed to a first reactor (108) to carry out a reverse water gas shift reaction at a predetermined weight hourly space velocity, at the second predetermined temperature and at the predetermined pressure in the presence of a catalyst to obtain a second stream (14) comprising carbon monoxide, water, unconverted hydrogen and unconverted carbon dioxide.

[0138] In accordance with an embodiment of the present disclosure, the second stream has a temperature in the range of 500 °C to 550 °C.

[0139] In accordance with an embodiment of the present disclosure, the second stream has a molar ratio of carbon dioxide to water in the range of l:0.8 to 1:1.5.

[0140] In accordance with the present disclosure, the catalyst is an alkali carbonate impregnated alumina based support, and the alkali carbonate in the catalyst is present in an amount in the range of 5 mass% to 20 mass% with respect to the total mass of the catalyst. The alkali carbonate is dipotassium carbonate (K2CO3) and disodium carbonate (Na2CC>3), and the alumina based support is selected from the group consisting of gamma-alumina, silica-alumina, boehmite, pseudo-boehmite and gibbsite. In an exemplary embodiment, the catalyst is dipotassium carbonate impregnated on a gamma-alumina support (K2CO3 / Y-AI2O3) with respect to the total mass of the catalyst.

[0141] In an exemplary embodiment, the catalyst is 10 mass% dipotassium carbonate impregnated on gamma-alumina support (K2CO3 / Y-AI2O3) with respect to the total mass of the catalyst.

[0142] In accordance with the present disclosure, the predetermined weight hourly space velocity of feeding the catalyst is in the range of 2 hr"1to 6 hr"1. In an exemplary embodiment, the weight hourly space velocity of feeding the catalyst is 3 hr"1. In another exemplary embodiment, the weight hourly space velocity of feeding the catalyst is 4 hr"1. In still another exemplary embodiment, the weight hourly space velocity is 6 hr"1.

[0143] The first reactor is loaded with K2CO3 / AI2O3 catalyst to achieve carbon dioxide conversion or carbon monoxide yield in the range of 50% to 60% per pass with minimal formation of lowerhydrocarbons such as methane and the like.

[0144] In accordance with the present disclosure, the first reactor is at least one selected from the group consisting of fixed bed reactor, fluidized bed reactor and moving bed reactor. In an exemplary embodiment, the first reactor is a bubbling fluidized bed reactor.

[0145] The second stream (14) is separated by using a carbon dioxide capture process to obtain a third stream (20) comprising the syngas (a mixture of carbon monoxide, unconverted hydrogen), and a fourth stream containing carbon dioxide and water.

[0146] In accordance with the present disclosure, the second stream (14) comprising carbon monoxide, water, unconverted carbon dioxide and unconverted hydrogen so obtained through reverse water gas shift reaction is integrated with carbon dioxide capture process, as illustrated in Fig.

[0147] 1 and 2.

[0148] In an embodiment, the second stream (14) is separated in a carbon dioxide capture unit (200).

[0149] In an embodiment, the third stream (20) 60 mol% to 70 mol% of hydrogen, 30 mol% to 40 mol% of carbon monoxide, 3 mol% to 4 mol% of carbon dioxide, and 0.25 mol% to 0.5 mol% of water. The syngas so obtained in the third stream (20) can be routed for different applications. The amount of the carbon dioxide in the third stream satisfies stoichiometric number between 2 to 2.05.

[0150] In accordance with the present disclosure, the third stream (20) comprises hydrogen and carbon monoxide in a molar ratio in the range of 1.2: 1 to 4: 1. The different molar ratios of hydrogen and carbon dioxide in the first stream (or pressurized stream) fed to reverse water gas shift reaction yields specific molar ratio of hydrogen to carbon monoxide. The molar ratio of hydrogen to carbon dioxide to in the first stream (10) is in the range of 2: 1 to 2.5: 1 results in syngas product with molar ratio of hydrogen to carbon monoxide in the range of 1.4: 1 to 1.8:1 which is useful for Fischer-Tropsch synthesis (FTS) processes comprising synthesis of olefins, heavy hydrocarbon (wax), oxo-compounds such as dimethyl ether and the like. On the other hand, higher molar ratio of hydrogen to carbon dioxide (3:1) results in the formation of syngaswith molar ratios of hydrogen and carbon monoxide in the range of 2: 1 to 2.5: 1 which finds application in the synthesis of alkane, alcohol and the like.

[0151] The fourth stream (28) containing carbon dioxide and water is cooled in a second heat exchanger (302) and fed to a gas-liquid separator (304) to obtain a water stream (30) and a fifth stream (32) containing carbon dioxide. In an embodiment, the second heat exchanger (302) is a condenser, which works at lower temperature to condense out water from the fourth stream (28). In another embodiment, the second heat exchanger (302) is a two phase separator that separates out CO2 gas from the fourth stream (28). The water settles to the bottom of the separator, while the gas phase rises to the top and exits from there.

[0152] In accordance with the present disclosure, the fourth stream (28) is cooled in the second heat exchanger to a temperature in the range of 40 °C to 60 °C. In an exemplary embodiment, the fourth stream is cooled in the second heat exchanger to a temperature of 50 °C.

[0153] In accordance with the present disclosure, the gas-liquid separator operates at a temperature in the range of 40 °C to 60 °C and at a pressure is in the range of 1 bar to 3 bar. In an exemplary embodiment, the gas-liquid separator operates at a temperature of 50 °C and at a pressure of 2 bar.

[0154] The fifth stream (32) so obtain after removal of water comprises carbon dioxide of a purity in the range of 95 mol% to 99 mol%. The fifth stream may have the reduced water content in the range of 0.05 mol% to 0.1 mol% to enhance carbon monoxide yield during recycling.

[0155] In accordance with the present disclosure, the fifth stream (32) containing carbon dioxide is recycled to the first reactor (108) through the compressor (102) to form a mixed feed stream (34) along with the first stream (10). The mixed feed stream (34) after being pressurized in the compressor (102) is fed to the first heat exchanger (104) for further processing. Due to carbon dioxide capture process and removal of water, there was minimum loss of CO2 gas, thereby reducing the recycle molar ratio to the range of 1.0 to 2.0. The recycling of the fifth stream to the first reactor produces water-free syngas of exact same stoichiometry as required for methanol synthesis.Fig. 2 also illustrates the heat integration to compensate heat requirement in the carbon dioxide capture process through the heat available with the second stream. The heat content in the second stream is recovered with the help of thermic fluid such as Dowtherm™ in the second heat exchanger. Dowtherm™ is a mixture of diphenyl and diphenyl oxide, which forms a eutectic mixture that has advantageous thermal properties.

[0156] The removal of water from the first reactor (108) is demonstrated to be a key element in improving the catalytic activity and the efficiency of reverse water gas shift reaction (rWGS) reaction.

[0157] Hence, the reverse water gas shift reaction with an option to recycle the separated carbon dioxide and water scheme employs flexibility in tuning specific ratio of hydrogen to carbon monoxide in the final syngas product with improved efficiency.

[0158] Carbon dioxide capture process in accordance with the present disclosure

[0159] In accordance with the present disclosure, the second stream is separated by using carbon dioxide capture process, the carbon dioxide capture process comprises the following steps: The second stream (14) is sequentially cooled to a temperature in the range of 200 °C to 230 °C in the first heat exchanger (104) and to a temperature in the range of 70 °C to 90 °C in a third heat exchanger (202) to obtain a cooled stream. In an exemplary embodiment, the second stream is cooled sequentially to a temperature of 215 °C in the first heat exchanger ( 104) and to a temperature of 80 °C in a third heat exchanger (202) to obtain a cooled stream.

[0160] The cooled stream is fed to a second reactor (204) containing a sorbent followed by treating at a temperature in the range of 70 °C to 90 °C and at a pressure in the range of 1.5 bar to 3.5 bar for a time period in the range of 5 minutes to 15 minutes to obtain a rich capture media (22) having adsorbed unconverted carbon dioxide and water on the sorbent, and the third stream (20) comprising the syngas (a mixture of carbon monoxide, unconverted hydrogen and other contents). In an exemplary embodiment, the cooled stream is fed to a second reactor (204) containing a sorbent followed by treating the cool stream with the sorbent at a temperature of80 °C and at a pressure of 2 bar for a time period of 7.5 minutes to obtain the rich capture media (22) having adsorbed unconverted carbon dioxide and water on the sorbent, and the third stream (20) comprising syngas (a mixture of carbon monoxide, unconverted hydrogen and other contents).

[0161] In accordance with the present disclosure, the sorbent is an alkali carbonate impregnated alumina based support, and alkali carbonate in the sorbent is present in an amount in the range of 25 mass%to 35 mass%. The alkali carbonate is selected from dipotassium carbonate (K2CO3) and disodium carbonate (NazCCh); and the alumina based support is selected from the group consisting of gamma-alumina, silica-alumina, boehmite, pseudo-boehmite and gibbsite.

[0162] In an exemplary embodiment, the sorbent is 30 mass% of dipotassium carbonate impregnated in gamma-alumina support (K2CO3 / AI2O3).

[0163] In accordance with the present disclosure, the second reactor (204) is at least one selected from the group consisting of fixed bed reactor, fluidized bed reactor and moving bed reactor.

[0164] The rich capture media (22) is heated to a temperature in the range of 90 °C to 120 °C in a capture media heater (206).

[0165] In accordance with the present disclosure, the rich capture media (22) is pre-heated in a capture media heater (206) to a temperature in the range of 90 to 120 °C before supplying to the third reactor (208) for regeneration. In an exemplary embodiment, the rich capture media (22) is preheated in a capture media heater (206) to a temperature of 110 °C.

[0166] The rich capture media (22) is regenerated in a third reactor (208) at a temperature in the range of 130 °C to 150 °C for a time period in the range of 2 minutes to 8 minutes with the help of a low pressure (LP) steam to obtain a lean capture media (24) containing the sorbent devoid of carbon dioxide and water, and the fourth stream (28) containing carbon dioxide and water. In an exemplary embodiment, the rich capture media is regenerated in a third reactor (208) at a temperature of 140 °C for a time period of 3.5 minutes to obtain a lean capture media (24) containing the sorbent devoid of carbon dioxide and water, and the fourth stream (28) containing carbon dioxide and water.In accordance with the present disclosure, the third reactor (208) is at least one selected from the group consisting of fixed bed reactor, fluidized bed reactor and moving bed reactor. In an exemplary embodiment, the second reactor (204) and the third reactor (208) are circulating bubbling fluidized bed reactor.

[0167] The lean capture media is pre-cooled in a capture media cooler and recycled to the second reactor (204).

[0168] The carbon dioxide is captured in the second reactor (204) by carbon dioxide capture process which follows carbonate -bicarbonate chemistry with the following reaction scheme:

[0169] Pretreatment:

[0170] Eq. (3)

[0171] K2CO3(S) + 1.5 H2O (g) = K2CO31.5 H2O (S) AH = -101 kJ / mol Adsorption:

[0172] Eq. (4)

[0173] K2CO31.5 H2O (s) + CO2(g) = 2KHCO3(S) + 0.5H2O (g) AH = - 40 kJ / mol Regeneration:

[0174] Partial regeneration'.

[0175] Eq. (5)

[0176] 2KHCO3(S) + 0.5 H2O (g) = K2CO31.5 H2O (s) + CO2(g) AH = + 40 kJ / mol Full regeneration:

[0177] Eq. (6)

[0178] 2KHCO3= i cc^ + CO2+ H2O AH = +141kJ / mol

[0179] The exothermic adsorption reaction heat is controlled in the second reactor (204) by effective cooling arrangement.

[0180] The heat available with the thermic fluid, for example, Dowtherm™ from the fourth heat exchanger (216) at a temperature in the range of 185 °C to 215 °C is utilized to satisfy partial heat requirement in the third reactor (208). The mixed thermic fluid stream from the third reactor (208) and the capture media cooler (210) at the temperature in the range 120 °C to 125°C is utilized for heating the rich capture media in the capture media heater (206). Further, the thermic fluid is cooled from 95 °C to 70 °C in a thermic fluid cooler i.e. fourth heat exchanger (216)) and further circulated to the third heat exchanger (202) and the capture media cooler (210). The thermic fluid loss in the process is compensated with make-up quantity (26) of the thermic fluid at the inlet of the capture media cooler (210).

[0181] The carbon dioxide capture process limits the concentration of carbon dioxide and water in the third stream (20) obtained from the second reactor (204) in the range of 3 mol% to 4 mol% and in the range of 0.2 mol% to 0.5 mol%, respectively.

[0182] The carbon dioxide capture process of the present disclosure has a carbon dioxide removal efficiency in the range of 85% to 90%.

[0183] Methanol production from the so obtained syngas in accordance with the process of the present disclosure

[0184] The syngas (a mixture of hydrogen and carbon monoxide) so obtained in the form of the third stream (20) can be utilized formethanol production. Fig. 3 depicts an indirect process for the methanol production which comprises carbon dioxide hydrogenation through reverse water gas shift reaction followed by carbon dioxide capture, recycling of CO 2 to reverse water gas shift reaction for the generation of syngas and subsequently for methanol synthesis with the separation and purification steps. During methanol synthesis, the carbon monoxide conversion per pass is found to be in the range of 60 mol% to 70 mol% and methanol yield per pass is in the range of 65 mol% to 75 mol%. In accordance with the present disclosure, the purification of methanol is performed by using a series of distillation column.

[0185] In accordance with the present disclosure, the conversion of syngas to methanol is carried out in a fourth reactor in the presence of a supported metal oxide catalyst. The fourth reactor is at least one selected from a fixed bed, a fluidized bed and a moving bed. The metal oxide in the supported metal oxide catalyst is at least one selected from copper oxide and zinc oxide.

[0186] The present disclosure evaluates reverse water gas shift reaction operating condition needed toproduce a gas mixture with the composition compatible with the methanol production process requirements. In addition to Eq. (1), methanol synthesis reaction is exothermic reaction and takes place with loss in volume.

[0187] Eq. (7)

[0188] CO + 2H2= CH3OH AH25C = - 1 kJ / mol

[0189] The removal of carbon dioxide and water from the first reactor product stream (14) prior feeding to methanol converter significantly improves the methanol production. This is because water removal from the first reactor product stream enhances the carbon monoxide yield in the first reactor (108). Also, the removal of water from the reaction mixture also enhances the methanol yield in methanol converter. The syngas so obtained in the form of the third stream (20) from second reactor (204) as described and shown in Fig. 2 is characterized by the stoichiometric number (SN) which is defined as:

[0190] Eq. (8)

[0191]

[0192] The value of the parameter SN for feed gas mixture to methanol converter is maintained in the range of 2 and 2.05. This SN ratio can be maintained by achieving the carbon dioxide concentration in the third stream (20) of less than 7 mol%.

[0193] The third stream of syngas (20) so obtained has a higher molar ratio of carbon monoxide to carbon dioxide in the range of 2.5 to 9.0, which increases the reaction rate and conversion per pass in the methanol converter and also reduces the formation of water and hence, decrease rate of catalyst deactivation in the methanol production. The process of the methanol conversion mostly operates by using copper oxide and zinc oxide based catalysts and in gas phase. The main differences among different processes of methanol synthesis are related to the reactor design and catalyst arrangement. The syngas so obtained in the form of third stream is pressurized to 80 bar to 100 bar and heated to temperature in the range of 215 °C to 240 °C.

[0194] As shown in Fig. 3, the mixed feed gas stream for methanol conversion comprises the third stream (20) and a recycle stream (CO and H2) from methanol converter after separation. Themixed feed gas stream, having a hydrogen to carbon oxides (carbon dioxide and carbon monoxide) molar ratio in the range of 3 : 1 to 8 : 1 are fed to the methanol converter. The methanol converter is followed by methanol separation and purification unit operations as mentioned in conventional processes. By using the syngas so obtained by using the process of the present disclosure improved the purity of methanol in the range of 98% to 99.9%.

[0195] Fig. 4 depicts direct hydrogenation of carbon dioxide for methanol production without following any process route for production of syngas. The reaction scheme for direct hydrogenation is shown in Eq. (9) wherein the carbon dioxide and hydrogen react together to form methanol and water.

[0196] Eq. (9)

[0197] CO2+ 3H2= CH3OH + H2O AH = -49.5 kJ / mol

[0198] The aforementioned formed water consumes one third of the hydrogen that is charged for reaction, requiring more hydrogen than in the methanol formation reaction from the syngas. The methanol formation reaction is exothermic and take place with a loss in reaction volume; the high pressure and low temperature helps to achieve a higher conversion. A mixed feed gas stream, having a hydrogen to carbon dioxide molar ratio in the range of 3: 1 to 4: 1 are fed to a methanol converter. The methanol converter is followed by methanol separation and purification unit operations as mentioned in conventional processes.

[0199] The reverse water gas shift reaction can be regarded as a process or as an intermediate reaction in other carbon dioxide conversion processes. The carbon monoxide product from reverse water gas shift reaction can be used directly as industrial intermediate for value added chemicals. The carbon dioxide and hydrogen content in the feed is significant in determining the overall conversion and product selectivity of the reaction. For equimolar amounts of carbon dioxide and hydrogen in the pressurized stream to reverse water gas shift reactor, the resulting syngas (at complete conversion and water removal) mainly yields carbon monoxide-rich syngas, suited for use in carbonylation reactions, e.g. carbonylation of methanol into acetic acid.For the pressurized stream with hydrogen and carbon dioxide in the molar ratio of 2:1 may results in a syngas composition with hydrogen to carbon monoxide of about 1.4:1, primarily used for producing oxygenates, like dimethyl ether (DME). The pressurized stream containing hydrogen and carbon dioxide in the molar ratio of 3: 1 may result in the syngas composition with hydrogen to carbon monoxide molar ratio of about 2.3:1, which can be advantageously used in olefin production by Fisher Tropsch synthesis (FTS), methanol, oxo-alcohols synthesis and the like. The carbon dioxide concentration in the final syngas for FTS and oxo-alcohol production should be restricted to very low level. Thus, the syngas composition need be tuned and controlled to match the desired end-use requirements. Commercial processes for converting the syngas to methanol and long chain hydrocarbons through FTS are mature technologies which makes reverse water gas shift process an attractive platform to feed carbon dioxide as Ci building block for the chemical industry. Therefore, the reverse water gas shift catalysts and process of the present disclosure are being developed for commercially viable pathway to recycle carbon to fullest extent. The process of the present disclosure can be flexibly and efficiently integrated with intensified industrial scale carbon dioxide-based processes and able to deliver syngas at the desired operation conditions and yields.

[0200] The process of the present disclosure is capable to achieve carbon dioxide conversion of 50%, and carbon monoxide yield of -50% in the reverse water gas shift reaction with minimum formation of by-product such as methane and the like. In an exemplary embodiment, the conversion of carbon dioxide is 52% at 600 °C.

[0201] The carbon dioxide capture process in accordance with the present disclosure is energy efficient for removal of water from the second stream.

[0202] The present disclosure takes credits of rWGS catalyst and process benefits which can be flexibly and efficiently integrated with intensified industrial scale CCF-bascd processes and able to deliver syngas at the desired operation, conditions and yields . The process of the present disclosure if coupled with downstream methanol production process, the life cycle cost of methanol will be significantly reduced by 15% to 20% as compared to direct CO2 conversion methanol process.The process of the present disclosure can have tunable hydrogen to carbon monoxide ratio in the third stream and restricted or no water content to be used for different process applications.

[0203] The foregoing description of the embodiments has been provided for purposes of illustration and is not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment but are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.

[0204] The present disclosure is further illustrated herein below with the help of the following nonlimiting examples. The experiments disclosed under these examples herein are intended merely to facilitate an understanding of how the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the experiments should not be construed as limiting the scope of embodiments herein. These laboratory-scale experiments can be scaled up to an industrial / commercial scale and the results obtained can be extrapolated to industrial / commercial scale.

[0205] EXPERIMENTAL DETAILS

[0206] Example 1- The process for the generation of syngas in accordance with the present disclosure and its implication for the production of methanol

[0207] As depicted in Fig. 3, the process of the generation of syngas in accordance with the present disclosure and its implication for the production of methanol (an indirect methanol production process) explained as follows:

[0208] (i) carbon dioxide hydrogenation through reverse water gas shift reaction followed by carbon dioxide capture and recycling; (ii) methanol conversion by using syngas (carbon monoxide and hydrogen); (iii) methanol separation and recycling of unconverted carbon monoxide and hydrogen; and (iv) methanol purification.

[0209] The process as disclosed in Fig. 4 illustrates a conventional direct methanol production process.The process as depicted in Fig. 3 was compared with a conventional direct methanol production process. The direct / conventional methanol production process explained as follows:

[0210] (i) methanol conversion by using carbon dioxide and hydrogen; (ii) methanol separation and recycling of unconverted carbon dioxide and hydrogen; and (iii) methanol purification as shown in Fig. 4.

[0211] The removal of carbon dioxide from the first reactor product stream i.e. the second stream (14) involved dual benefits such as increase in the overall carbon dioxide conversion in the first reactor (108) and decrease in the recycle volume in methanol converter recycle loop. The selectivity to carbon monoxide of the reverse water gas shift reaction in the first reactor (108) was fundamental to achieve enough production of methanol in the methanol converter. The higher concentration of the carbon dioxide in the feed stream to methanol conversion was also not beneficial to methanol synthesis catalyst activity due to lower rate of carbon dioxide conversion to methanol as compared to carbon monoxide.

[0212] The separation of water from the second stream (14) helps in enhancing the carbon monoxide yield appreciably. The process of the present disclosure introduced lower content of carbon dioxide and water in the feed stream to the methanol conversion due to the introduction of carbon dioxide capture process. Also, with higher proportion of hydrogen and carbon oxides (carbon dioxide and carbon monoxide) molar ratio (3:1) in the mixed feed stream to methanol convertor enhanced the methanol yield significantly to >71% with low recycle molar ratio (=1.55). The lower recycle ratio facilitated in lowering the CAPEX of the methanol convertor and the multi-stage recycle compressor. The recycle ratio in the indirect process was very low, which gave immense benefits in reduction in CAPEX of methanol convertor and multi-stage recycle compressor.

[0213] The minimal concentration of carbon dioxide and water in the feed stream to methanol convertor in the indirect process significantly increased the methanol yield. The performance characteristics of the indirect process and the direct process for methanol production are shown below in Table 1 and 2 respectively.Table 1. Performance characteristics of indirect process

[0214]

[0215]

[0216] The results in Table 1 are provided based on multiple runs

[0217] In the first reactor, the catalyst used was 10 mass% of dipotassium carbonate impregnated on a gamma-alumina support. In the second reactor, the sorbent used was 30 mass% of dipotassium carbonate impregnated on a gamma-alumina support.

[0218] Table 2. Performance characteristics of direct / conventional process

[0219]

[0220] As per reaction kinetics of the direct process, the water formation as shown in Eq. (9) requires special attention to protect the methanol conversion catalyst. The recycle ratio was quite high which resulted in higher feed compression cost and reactor size and hence, operating andcapital expenses. With continued recycle, the partial pressure of the by-product (methane) formed increased and hence, significant amount of stream needed to be purged out. The purging operation resulted in loss of valuable hydrogen which led to decrease in the final methanol yield. Thus, the indirect process of methanol production was found to be beneficial as compared to the direct process of methanol production. The suitable use of catalyst results in increase in reverse water gas shift reaction activity and suppressing carbon dioxide methanation.

[0221] Example 2- Time-on-stream evaluation of K2CO3 / Y-AI2O3 for the generation of syngas in accordance with the present disclosure

[0222] Fig. 5 illustrates a time-on-stream evaluation results for 10 mass% K2CO3 impregnated on y-AI2O3 depicting variation in carbon dioxide conversion and carbon monoxide yield as a function of time in accordance with the process of the present disclosure. Fig. 5 depicts that the carbon dioxide conversion and carbon monoxide yield were 57% and 55% respectively with respect to time. The K2CO3 / Y-AI2O3 catalyst was found to be active and stable for more than 200 hours at 550 °C and 3 bar.

[0223] The process described in the above-mentioned scheme for carbon dioxide hydrogenation through reverse water gas shift reaction was carried out with different weight hourly space velocity (WHSV) in the range of 3 hr"1to 6 hr"1for 10 mass% K2CO3 / Y-AI2O3 catalyst. The results are illustrated in Fig. 6 and it was inferred that with decrease in WHSV of the gas entering the reactor, both carbon dioxide conversion and carbon monoxide yield increases.

[0224] TECHNICAL ADVANCEMENTS

[0225] The present disclosure described herein above has several technical advantages including, but not limited to, the realization of:

[0226] a process for the generation of syngas that:

[0227] reduces the volume of recycle, thereby eliminating the need of larger equipments; and - can tune the molar ratios of hydrogen and carbon monoxide in the generated syngas to be used in various applications;and a system for the generation of syngas that:

[0228] - is simple and energy efficient.

[0229] The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

[0230] The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and / or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

[0231] Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

[0232] The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.

[0233] Any discussion of documents, acts, materials, devices, articles or the like that has been includedin this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

[0234] The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher / lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.

[0235] While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

Claims

CLAIMS:

1. A process for the generation of syngas, said process comprising the following steps:(a) compressing a first stream (10) comprising a predetermined molar ratio of hydrogen and carbon dioxide to a predetermined pressure in at least one compressor (102) to obtain a pressurized stream;(b) pre-heating the pressurized stream in a first heat exchanger (104) to a first predetermined temperature followed by heating in a furnace (106) to a second predetermined temperature to obtain a hot stream;(c) feeding said hot stream to a first reactor (108) at a predetermined weight hourly space velocity, at said second predetermined temperature and at said predetermined pressure in the presence of a catalyst to obtain a second stream (14) comprising carbon monoxide, water, unconverted hydrogen and unconverted carbon dioxide; (d) separating said second stream (14) to obtain• a third stream (20) comprising said syngas; and• a fourth stream (28) containing carbon dioxide and water; and (e) cooling said fourth stream (28) containing carbon dioxide and water in a second heat exchanger (302) and feeding to a gas-liquid separator (304) to obtain a water stream (30) and a fifth stream (32) containing carbon dioxide.

2. The process as claimed in claim 1, wherein said second stream (14) is separated by using a carbon dioxide capture process, said carbon dioxide capture process comprises the following steps:(i) cooling said second stream (14) to a temperature in the range of 70 °C to 90 °C in sequentially arranged said first heat exchanger (104) and a third heat exchanger (202) to obtain a cooled stream;(ii) feeding said cooled stream to a second reactor (204) containing a sorbent and treating at a temperature in the range of 70 °C to 90 °C and at a pressure in the range of 1.5 bar to 3.5 bar for a time period in the range of 5 minutes to 15 minutes to obtain• a rich capture media (22) having adsorbed unconverted carbon dioxide and water on said sorbent; and• said third stream (20) comprising syngas;(iii) heating said rich capture media (22) in a capture media heater (206) to a temperature in the range of 90 °C to 120 °C;(iv) regenerating said rich capture media (22) in a third reactor (208) at a temperature in the range of 130 °C to 150 °C for a time period in the range of 2 minutes to 8 minutes to obtain• a lean capture media (24) containing said sorbent devoid of carbon dioxide and water; and• said fourth stream (28) containing carbon dioxide and water;and(v) pre-cooling said lean capture media (24) in a capture media cooler (210) and recycling to said second reactor (204).

3. The process as claimed in claim 1, wherein said fifth stream (32) containing carbon dioxide is recycled to said first reactor (108) through said compressor (102) to form a mixed feed stream (34).

4. The process as claimed in claim 1 , wherein said predetermined molar ratio of hydrogen to carbon dioxide is in the range of 1 : 1 to 4: 1.

5. The process as claimed in claim 1, wherein said predetermined pressure is in the range of 2.5 bar to 5 bar.

6. The process as claimed in claim 1, wherein said first predetermined temperature is in the range of 300 °C to 450 °C.

7. The process as claimed in claim 1, wherein said second predetermined temperature is in the range of 550 °C to 650 °C.

8. The process as claimed in claim 1, wherein said predetermined weight hourly space velocity of feeding said hot stream is in the range of 2 hr"1to 6 hr"1.

9. The process as claimed in claim 1, wherein said catalyst is an alkali carbonate impregnated alumina based support, and said alkali carbonate in said catalyst is present in an amount in the range of 5 mass% to 20 mass%.

10. The process as claimed in claim 9, wherein said alkali carbonate is selected from dipotassium carbonate (K2CO3) and disodium carbonate (Na2CC>3); and said alumina based support is selected from the group consisting of gamma-alumina, silica-alumina, boehmite, pseudo-boehmite and gibbsite.

11. The process as claimed in claim 9, wherein said catalyst is 10 mass% dipotassium carbonate impregnated on gamma-alumina support (K2CO3 / Y-AI2O3).

12. The process as claimed in claim 2, wherein said sorbent is an alkali carbonate impregnated alumina based support, and said alkali carbonate in said sorbent is present in an amount in the range of 25 mass% to 35 mass%.

13. The process as claimed in claim 12, wherein said alkali carbonate is selected from dipotassium carbonate (K2CO3) and disodium carbonate (Na2CO3); and said alumina based support is selected from the group consisting of gamma-alumina, silica-alumina, boehmite, pseudo-boehmite and gibbsite.

14. The process as claimed in claim 12, wherein said sorbent is 30 mass% dipotassium carbonate impregnated on gamma-alumina support (K2CO3 / Y-AI2O3).

15. The process as claimed in claim 1, wherein said furnace (106) is heated by combusting natural gas (NG) in air (12) to emit flue gas (16).

16. The process as claimed in claim 1, wherein said fourth stream (28) is cooled in a second heat exchanger (302) to a temperature in the range of 40 °C to 60 °C.

17. The process as claimed in claim 1, wherein said gas-liquid separator (304) operates at a temperature in the range of 40 °C to 60 °C and at a pressure is in the range of 1 bar to 3 bar.

18. The process as claimed in claim 1, wherein said third stream (20) of syngas comprises 60 mol% to 70 mol% of hydrogen, 30 mol% to 40 mol% of carbon monoxide, 3 mol% to 4 mol% of carbon dioxide, and 0.25 mol% to 0.5 mol% of water.

19. A system for the generation of syngas (1000), said system comprises:(i) a compressor (102) configured to receive a first stream (10) comprising a predetermined molar ratio of hydrogen and carbon dioxide, and further configured to compress said first stream (10) to a predetermined pressure to obtain a pressurized stream;(ii) a first heat exchanger (104) configured to receive said pressurized stream and further configured to pre-heat said pressurized stream to a first predetermined temperature to obtain a pre-heated stream;(iii) a furnace (106) configured to receive said pre-heated stream and further configured to heat said pre-heated stream to a second predetermined temperature to obtain a hot and pressurized stream;(iv) a first reactor (108) containing a catalyst, configured to receive said hot and pressurized first stream at a predetermined weight hourly space velocity, and further configured to carry out a reverse water gas shift reaction (rWGS) at said second predetermined temperature and at said predetermined pressure to obtain a second stream (14) comprising carbon monoxide, water, unconverted carbon dioxide and unconverted hydrogen;(v) a carbon capture unit (200) configured to receive said second stream and further configured to separate said second stream (14) into a third stream (20) comprising said syngas and a fourth stream (28) containing carbon dioxide and water;(vi) a second heat exchanger (302) configured to receive said fourth stream (28) and further configured to cool said fourth stream; and(vii) a gas-liquid separator (304) configured to receive said cooled fourth stream and further configured to separate said cooled fourth stream into a water stream (30) and a fifth stream (32) containing carbon dioxide.

20. The system as claimed in claim 19, wherein said carbon capture unit (200) comprises:(i) at least one third heat exchanger (202) configured to receive said second stream (14) and further configured to cool said second stream to a temperature in the range of 70 °C to 90 °C;(ii) a second reactor (204) containing a sorbent, configured to receive said cooled second stream and further configured to treat said cooled second stream at a temperature in the range of 70 °C to 90 °C and at a pressure in the range of 1.5 bar to 2.5 bar for a time period in the range of 5 minutes to 15 minutes to obtain(a) a rich capture media (22) having adsorbed unconverted carbon dioxide and water on said sorbent; and(b) said third stream (20) comprising syngas;(iii) a capture media heater (206) configured to receive said rich capture media (22) and further configured to heat said rich capture media to a temperature in the range of 90 °C to 120 °C;(iv) a third reactor (208) configured to receive said heated rich capture media and further configured to regenerate said rich capture media at a temperature in the range of 130 °C to 150 °C for atime period in the range of 2 minutes to 8 minutes to obtain• a lean capture media (24) containing said sorbent devoid of carbon dioxide and water; and• said fourth stream (28) containing carbon dioxide and water; and (v) a capture media cooler (210) configured to receive said lean capture media (24) and further configured to cool said lean capture media and recycle to the second reactor (204).

21. The system as claimed in claim 19, wherein said compressor (102) is further configured to receive and recycle said fifth stream (32) containing carbon dioxide.

22. The system as claimed in claim 19, wherein said second reactor (204) is equipped with a cool water circulation unit (212) to maintain the temperature within said second reactor (204).

23. The system as claimed in claim 19, wherein said third reactor (208) is equipped with a low pressure steam circulation unit (214) to maintain the temperature within said third reactor (208).

24. The system as claimed in claim 19 further comprises a benefit unit (400), said benefit unit (400) is configured to receive the flue gas (16) emitted from said furnace (106) and further configured to heat water to generate high pressure steam (18).

25. The system as claimed in claim 19, wherein said third heat exchanger (202), said capture media heater (206), and said capture media cooler (210) utilizes a thermic fluid as a heat exchange media.

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