A method for carrying out a water-gas shift reaction

Abstract

The application discloses a method for carrying out water-gas shift reaction and belongs to the technical field of hydrogen production. The method comprises the following steps: contacting gaseous reaction raw material containing carbon monoxide with liquid water in a fixed bed reactor to form a catalyst and reacting; the method uses a carbon-bonded supported noble metal catalyst with high activity, high hydrothermal stability and high mechanical strength to make gaseous reaction raw material containing carbon monoxide with a volume fraction of greater than or equal to 30% and liquid water react in a fixed bed reactor under the conditions of 200-300 DEG C and 3-7 MPa to produce hydrogen. The application overcomes the problem of sharp temperature rise when the traditional process uses an adiabatic reactor to carry out gas-solid two-phase water-gas shift reaction, is beneficial to simplifying a reaction device and a reaction process, reducing reaction energy consumption and saving operation cost, and the preparation method of the water-gas shift reaction catalyst is simple and easy to implement, and can be realized in catalyst preparation processes with different scales such as experimental research and industrial production.

Description

Technical Field

[0001] This application relates to a method for carrying out a water-gas shift reaction, belonging to the field of hydrogen production technology. Background Technology

[0002] Water-gas shift reaction (SFT) refers to the reaction of carbon monoxide and water vapor to produce hydrogen and carbon dioxide (CO + H₂O = H₂ + CO₂). This reaction is an important process in industrial production, mainly used to adjust the CO / H₂ ratio of syngas, produce hydrogen, and remove carbon monoxide. Existing industrial plants all use adiabatic reactors to carry out the gas-solid two-phase reaction at 200-500℃. The gas phase consists of reactants containing carbon monoxide and water vapor, while the solid phase is the catalyst. The gas-solid two-phase water-gas shift reaction is a strongly exothermic reaction with a heat of reaction of approximately 40 kJ / mol. The heat of reaction accumulates in the adiabatic reactor, causing a significant increase in temperature. Excessively high temperatures are detrimental to plant control and can lead to catalyst deactivation. Therefore, in industrial production, a multi-stage conversion process is usually adopted for feedstock gas containing high concentrations of carbon monoxide. Before the next stage of conversion reaction, the temperature of the reactants is reduced by heat exchange (for example, specific examples of the above process are provided in patents such as CN1280180C, CN102001623B, CN102971252B, CN103508416B, CN102992264B, CN103449365B, CN104340958B, CN104098069B, and CN105084313B).

[0003] Compared to adiabatic water gas shift reaction processes, isothermal water gas shift reaction simplifies the reaction process. Patent document CN1204038C discloses an isothermal sulfur-resistant carbon monoxide shift reaction process. This process uses a tubular or internally heat-exchange coil reactor, removing the heat of reaction from the catalyst bed through a heat transfer medium, thereby ensuring the bed temperature is close to isothermal. Patent document CN104085855B discloses an external reverse humidification isothermal carbon monoxide shift reaction process using a dry gas detoxifier, which incorporates heat exchange bent tubes within the reactor. Patent document CN110550602B discloses a high-concentration, controllable semi-isothermal carbon monoxide shift reaction process for carbonyl synthesis. This process uses a reactor divided into an isothermal reaction zone and an adiabatic reaction zone, with heat exchange tubes connected from bottom to top in the isothermal reaction zone.

[0004] By replacing the water vapor used as a reactant with liquid water, a multiphase water-gas shift reaction can be achieved under the action of a solid-phase catalyst. The heat of reaction in this process is close to zero, thus maintaining a stable reaction temperature. This overcomes the problem of severe temperature rise in gas-solid two-phase water-gas shift reactions using adiabatic reactors. Because the liquid water is in direct contact with the catalyst, the heat transfer efficiency is much higher than that of isothermal water-gas shift reaction devices with heat exchange tubes installed within the catalyst bed. Under suitable liquid water input conditions, the water-gas shift reaction can proceed in a near-isothermal state. This significantly simplifies the reaction apparatus and greatly reduces operating costs. For example, patent GB1085613A discloses a reactor for reacting gases, vapors, or liquids, which can be used for multiphase water-gas shift reactions. Patent CN116239082A discloses a method for carrying out a water-gas shift reaction. The method involves dividing the reaction raw materials required for the water-gas shift reaction into two parts: a gas phase and a liquid phase. The gas phase reaction raw materials contain carbon monoxide and water vapor, while the liquid phase reaction raw materials contain water. The gas phase reaction raw materials and the liquid phase reaction raw materials are fed into a reactor containing a catalyst in two separate streams. The two reaction raw materials come into contact in the reactor and undergo a water-gas shift reaction.

[0005] In addition to the above characteristics, multiphase water-gas shift reaction (MWS) also facilitates the complete conversion of carbon monoxide. In gas-solid two-phase reactions, increasing the water vapor content in the gas phase reactants can promote the MWS reaction. However, transporting water vapor is an energy-intensive process, and simply increasing the water vapor content would significantly increase operating costs, making it impractical. In the liquid phase reaction, water in the feedstock does not need to be pre-vaporized and is directly fed into the reactor in liquid form, thus eliminating the energy consumption required to transport the corresponding amount of water vapor. Simultaneously, it ensures that the molar ratio of water to carbon monoxide in the reactor remains high, thereby promoting the reaction and ensuring the complete conversion of carbon monoxide simply by increasing the water volume without increasing energy consumption.

[0006] Compared to the gas-solid two-phase water-gas shift reaction, the multiphase water-gas shift reaction is characterized by the presence of liquid water in the reaction system. The presence of liquid water leads to different reaction mechanisms, such as hindering the decomposition of formic acid intermediates into hydrogen and carbon dioxide. At the same time, the hydrogen ions and hydroxide ions generated by the high-temperature dissociation of liquid water can react with species on the catalyst surface, leading to catalyst deactivation. For example, the Cu / ZnO / Al2O3 catalyst commonly used in industrial gas-solid two-phase water-gas shift processes undergoes hydrolysis in multiphase water-gas shift processes (ELLIOTT DC, SEALOCK L J. Aqueous catalyst systems for the water-gas shift reaction.1. Comparative catalyst studies[J]. Industrial & Engineering Chemistry Product Research and Development, 1983, 22: 426-431). Pt-Mo2C / C catalysts exhibit poor stability and low activity in heterogeneous water-gas shift reactions (XU Y, LI J, LIW, et al. Direct conversion of CO and H2O into liquid fuels under mild conditions[J]. Nature Communications, 2019, 10: 1389). Furthermore, under the influence of liquid water, commonly used catalyst supports for gas-solid two-phase water-gas shift reactions, such as cerium oxide, undergo hydrolysis, leading to the aggregation of active metals, while molecular sieves experience a decrease in specific surface area due to framework collapse. Therefore, hydrothermal stability is crucial for developing highly efficient heterogeneous water-gas shift reaction catalysts.

[0007] Multiphase water-gas shift reaction catalysts not only need high activity, selectivity, and hydrothermal stability, but also ideal macroscopic structure and mechanical strength. Meeting these requirements necessitates suitable molding methods. Catalysts and their supports are typically powders, which need to be molded into particles with specific shapes. To achieve the desired molding effect, binders are added to the powder during the molding process to improve its adhesion and agglomeration. Commonly used binders include magnesium oxide-magnesium chloride, water glass-calcium chloride, aluminum sol, and silica sol. However, under hydrothermal conditions, alumina can be transformed into the more stable boehmite; in the range of 150-180℃, the activation energy of this reaction is only 15.9±4.8 kJ / mol (KOICHUMANOVA K, GUPTAK BSS, LEFFERTS L, et al. An in situ ATR-IR spectroscopy study of aluminums under aqueous phase reforming conditions[J]. Physical Chemistry Chemical Physics, 2015, 17: 23795). Not only alumina, but also magnesium oxide, silicon dioxide, and other materials undergo structural changes during hydrothermal reforming due to their own chemical reactions (WEN G, XU Y, MAH, et al. Production of hydrogen by aqueous-phase reforming of glycerol[J]. International Journal of Hydrogen Energy, 2008, 33: 6657). With the change in binder structure, the accessibility of active components decreases significantly; simultaneously, the mechanical strength of the catalyst is also significantly impaired. In other words, the development and industrial application of multiphase water-gas shift technology is still constrained by the progress of catalyst forming technology suitable for hydrothermal reactions. Summary of the Invention

[0008] To address the limitation on industrial application of existing water-gas shift reaction technologies due to catalyst molding, this application proposes a multiphase water-gas shift reaction technology.

[0009] The technical solution adopted in this application is as follows:

[0010] According to a first aspect of this application, a method for carrying out a water-gas shift reaction is provided, comprising the following steps:

[0011] A gaseous reactant containing carbon monoxide is brought into contact with liquid water in a fixed-bed reactor to form a catalyst and react.

[0012] The volume fraction of carbon monoxide in the gaseous reaction feedstock containing carbon monoxide is ≥30%;

[0013] The conditions for contacting and reacting the catalyst in the fixed-bed reactor include: a reaction temperature of 200-300℃ and a reaction pressure of 3-7MPa;

[0014] The molding catalyst was prepared using the following method:

[0015] (1) Obtain catalyst powder;

[0016] (2) A mixture containing catalyst powder, phenolic resin and solvent is shaped and then carbonized by programmed temperature rise to form a shaped body, thereby obtaining the shaped catalyst;

[0017] The conditions for the temperature-heated carbonization process include:

[0018] The temperature is increased from room temperature to the pre-carbonization temperature at a rate of 5-10℃ / min, and then increased from the pre-carbonization temperature to the final carbonization temperature at a rate of 1-4℃ / min and held for 1-5 hours.

[0019] The pre-carbonization temperature is 250-450℃, and the final carbonization temperature is 500-750℃.

[0020] Optionally, the programmed heating carbonization process is carried out in an inactive atmosphere, such as a nitrogen atmosphere.

[0021] Optionally, the process of heating and carbonizing further includes cooling the carbonized product to room temperature and then slowly exposing the carbonized product to air to obtain the shaped catalyst.

[0022] The molding catalyst used in this application is a carbon-bonded supported noble metal catalyst.

[0023] In the preparation process of the shaped catalyst in this application, the carbonization operation in step (2) adopts a segmented heating procedure of "fast first and slow later".

[0024] Optionally, the gas hourly space velocity (GHSV) of the gaseous reactant containing carbon monoxide is 500-2000 h⁻¹. -1 ;

[0025] The liquid hourly space velocity of the liquid water is 3-15 h⁻¹. -1 .

[0026] Optionally, the molar ratio of liquid water to carbon monoxide is 5-10.

[0027] Optionally, in step (1), the method for obtaining the catalyst powder includes the following steps:

[0028] The carrier is mixed with an aqueous solution containing active precious metals, dried, calcined, and then reduced at 350-700℃ for 1-12 hours to obtain catalyst powder.

[0029] Optionally, the reduction process is carried out in a reducing atmosphere, such as a hydrogen atmosphere.

[0030] Optionally, the active noble metal is palladium or platinum. The palladium- or platinum-containing raw materials used are corresponding metal acids, metal salts, or ammonia complexes, and the principles and methods for their selection are well known to those skilled in the art.

[0031] Optionally, the support is titanium dioxide or zirconium dioxide. The crystal phase of titanium dioxide can be anatase, rutile, or may contain an amorphous phase. The crystal phase of zirconium dioxide can be tetragonal, monoclinic, or may contain an amorphous phase. The preparation methods of the above-mentioned titanium dioxide and zirconium dioxide are well known to those skilled in the art, and commercially available reagents are available. Before use, the phase state, crystallite size, and aggregation state of the support can be further adjusted by calcination.

[0032] Optionally, the calcination conditions include: a calcination temperature of 300-600℃ and a calcination time of 4-24h.

[0033] Optionally, in step (1), the mass fraction of the active precious metal in the catalyst powder, expressed in elemental form, is 0.3%-6%. In step (1), it should be ensured that the aqueous solution containing the active precious metal is in full and uniform contact with the support so that the dispersion of the active precious metal on the support achieves the desired result. This can be achieved by means well known to those skilled in the art, such as adjusting the concentration of the aqueous solution containing the active precious metal.

[0034] Optionally, in step (2), the mass ratio of the catalyst powder to the phenolic resin is 1-3.

[0035] The catalyst molding process described in this application does not restrict the type or form of phenolic resin used; it can be commercially available phenolic resin, such as thermoplastic and thermosetting types, including solid, aqueous solution, and ethanol solution forms. When using solid phenolic resin as raw material, an organic solvent needs to be added to facilitate uniform mixing of the phenolic resin and catalyst powder. Considering factors such as solvent toxicity, source, price, and ease of operation, ethanol is preferred. When using aqueous solutions or ethanol solutions of phenolic resin, since they already contain a certain amount of solvent, no additional solvent needs to be added. However, during operation, a small amount of solvent may be added to reduce the viscosity of the mixture and facilitate contact and mixing between the phenolic resin and catalyst powder. The choice between adding water or ethanol depends on the properties of the phenolic resin solution.

[0036] Optionally, in step (2), the mixture forming process employs forming methods such as compression molding and extrusion molding. The operation procedures of these forming methods are well known to those skilled in the art, for example, in existing literature (Zhang Jiguang. Catalyst Preparation Process Technology [M]. Beijing: China Petrochemical Press, 2004), Ertl et al. (ERTL G, H, F, et al. Handbook of Heterogeneous Catalysis[M]. 2nd ed. Weinheim: Wiley, 2008).

[0037] Optionally, step (2) further includes drying, which is performed before and / or after molding. Drying can be performed using methods well known to those skilled in the art, such as air drying, oven drying, or vacuum drying.

[0038] Optionally, in step (2), the solvent is water or ethanol.

[0039] Optionally, in step (1), the support and the aqueous solution containing the active noble metal also contain an auxiliary metal; by introducing the auxiliary metal into the catalyst, the performance of the catalyst can be further improved, so as to facilitate the water-gas shift reaction.

[0040] The auxiliary metal is one of manganese, iron, nickel, and tin; the raw materials containing the auxiliary metal are the corresponding acetates, nitrates, chlorides, etc., and the principles and methods for their selection are well known to those skilled in the art.

[0041] The mass ratio of auxiliary metals to active precious metals in the catalyst powder, expressed in elemental form, is 0.5-5.

[0042] In step (1), the active precious metal and the auxiliary metal can be loaded onto the support together by preparing a mixed solution containing both. Alternatively, the active precious metal and the auxiliary metal can be loaded onto the support separately. When loading separately, there are no special requirements for the loading order; those skilled in the art can design the loading order based on the properties of the active precious metal raw material and the auxiliary metal raw material.

[0043] The beneficial effects of this application include:

[0044] The method for water-gas shift reaction provided in this application can achieve multiphase water-gas shift reaction while ensuring that the catalyst has high activity, high hydrothermal stability, and high mechanical strength. This allows for the efficient conversion of carbon monoxide (volume fraction ≥30%) through a single-stage shift process under near-isothermal conditions. This overcomes the problem of severe temperature rise in gas-solid two-phase water-gas shift reactions using adiabatic reactors, and is beneficial for simplifying the reaction apparatus and process, reducing reaction energy consumption, and saving operating costs. The method for preparing the water-gas shift reaction catalyst provided by this invention is simple and easy to implement, and can be achieved in catalyst preparation processes of different scales, including experimental research and industrial production. Detailed Implementation

[0045] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0046] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0047] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.

[0048] In the water-gas shift reaction described in the various embodiments of this application, pure carbon monoxide is used as the gaseous reaction feedstock. This extreme condition is chosen to verify the feasibility of the water-gas shift reaction method provided by this invention, and does not imply that the water-gas shift reaction method provided by this invention is only applicable to the case of pure carbon monoxide.

[0049] Example 1

[0050] Preparation of Pt / TiO2 catalyst powder: 5.0 mL of a dichlorotetraammineplatinum aqueous solution with a Pt concentration of 0.025 g / mL was mixed evenly with 3.0 g of rutile titanium dioxide. The mixture was air-dried at room temperature and then dried overnight in an oven at 120 °C. The dried product was calcined in a muffle furnace at 400 °C for 12 h and then reduced in a tube furnace under hydrogen atmosphere at 600 °C for 4 h to obtain Pt / TiO2 catalyst powder. The mass fraction of Pt was 4.0%.

[0051] Pt / TiO2 catalyst molding: 2.1g of the above Pt / TiO2 catalyst powder was mixed evenly with 1.5g of 70% water-soluble phenolic resin and air-dried at room temperature. The mass ratio of catalyst powder to phenolic resin in the air-dried product was 2.0. The air-dried product was pressed into ingots using a 20mm diameter mold under compression conditions of 16MPa for 5min. The resulting ingots were dried overnight in an oven at 120℃ and then carbonized in a tube furnace under nitrogen atmosphere. The carbonization heating program consisted of two stages. The first stage involved heating from room temperature to 300℃ at a heating rate of 5℃ / min; the second stage involved heating from 300℃ to 600℃ at a heating rate of 2℃ / min and holding at that temperature for 2h. After the holding period ended and the temperature was lowered to room temperature, the carbonized product was slowly exposed to air to obtain the molded Pt / TiO2 catalyst.

[0052] Water-gas shift reaction: The above-mentioned shaped Pt / TiO2 catalyst was crushed and sieved, and 20-40 mesh particles were loaded into a fixed-bed reactor. Air was purged with nitrogen and leaks were checked. The system pressure was adjusted to the target reaction pressure. Water was introduced into the reactor and the temperature was increased. After the temperature at the center of the bed reached the target reaction temperature, carbon monoxide was introduced into the reactor. The reaction conditions and results are shown in Table 1.

[0053] Example 2

[0054] Preparation of PdMn / ZrO2 catalyst: 3.1 mL of palladium nitrate aqueous solution with a concentration of 0.0097 g / mL (based on Pd), 0.6 mL of manganese nitrate aqueous solution with a concentration of 0.10 g / mL (based on Mn), and 3.0 g of zirconium dioxide containing both tetragonal and monoclinic phases were mixed evenly, air-dried at room temperature, and then dried overnight in an oven at 120 °C. The dried product was calcined in a muffle furnace at 500 °C for 8 h and reduced in a tube furnace under hydrogen atmosphere at 650 °C for 3 h to obtain PdMn / ZrO2 catalyst powder, wherein the mass fractions of Pd and Mn were 0.97% and 1.9%, respectively, and the Mn / Pd mass ratio was 2.0.

[0055] PdMn / ZrO2 catalyst molding: 2.5g of the above PdMn / ZrO2 catalyst powder was mixed evenly with 1.5g of thermosetting phenolic resin and 1.0g of ethanol. The mass ratio of catalyst powder to phenolic resin in the mixture was 1.7. The mixture was manually extruded into strips using a powder press equipped with a die with an opening diameter of 2mm, at an extrusion pressure of 7MPa. The resulting extruded strips were air-dried at room temperature and then carbonized in a tube furnace under a nitrogen atmosphere. The carbonization heating program consisted of two stages. The first stage involved heating from room temperature to 400℃ at a heating rate of 10℃ / min; the second stage involved heating from 400℃ to 550℃ at a heating rate of 1.5℃ / min and holding at that temperature for 3 hours. After the holding period ended and the temperature was lowered to room temperature, the carbonized product was slowly exposed to air to obtain the molded PdMn / ZrO2 catalyst.

[0056] Water-gas shift reaction: The above-mentioned shaped PdMn / ZrO2 catalyst was used for water-gas shift reaction. The reaction operation was the same as in Example 1. The reaction conditions and results are shown in Table 1.

[0057] Example 3

[0058] Preparation of PdFe / ZrO2 catalyst: 3.8 mL of palladium chloride aqueous solution (0.020 g / mL, Pd concentration), 0.5 mL of ferrous acetate aqueous solution (0.15 g / mL, Fe concentration) and 3.0 g of monoclinic zirconium dioxide were mixed evenly, air-dried at room temperature, and then dried overnight in an oven at 120 °C. The dried product was calcined in a muffle furnace at 450 °C for 10 h and reduced in a tube furnace under hydrogen atmosphere at 550 °C for 7 h to obtain PdFe / ZrO2 catalyst powder, wherein the mass fractions of Pd and Fe were 2.4% and 2.4%, respectively, and the Fe / Pd mass ratio was 1.0.

[0059] PdFe / ZrO2 catalyst molding: 2.2g of the above PdFe / ZrO2 catalyst powder was mixed evenly with 2.0g of 70% (w / w) water-soluble phenolic resin and dried overnight in an oven at 160℃. The mass ratio of catalyst powder to phenolic resin in the dried product was 1.6. The dried product was pressed into ingots using a 20mm diameter mold under compression conditions of 18MPa for 5min. The resulting ingots were carbonized in a tube furnace under a nitrogen atmosphere. The carbonization heating program consisted of two stages. The first stage involved heating from room temperature to 300℃ at a heating rate of 6℃ / min; the second stage involved heating from 300℃ to 700℃ at a heating rate of 1.5℃ / min and holding at that temperature for 1.5h. After the holding period ended and the temperature was lowered to room temperature, the carbonized product was slowly exposed to air to obtain the molded PdFe / ZrO2 catalyst.

[0060] Water-gas shift reaction: The above-mentioned shaped PdFe / ZrO2 catalyst was used for water-gas shift reaction. The reaction operation was the same as in Example 1. The reaction conditions and results are shown in Table 1.

[0061] Example 4

[0062] Preparation of PtNi / TiO2 catalyst: 3.0 mL of a platinum tetrachloride aqueous solution with a Pt concentration of 0.0066 g / mL, 0.2 mL of a nickel nitrate aqueous solution with a Ni concentration of 0.16 g / mL, and 3.0 g of anatase phase titanium dioxide were mixed evenly, air-dried at room temperature, and then dried overnight in an oven at 120 °C. The dried product was calcined in a muffle furnace at 500 °C for 10 h, and then reduced in a tube furnace at 500 °C under hydrogen atmosphere for 6 h to obtain PtNi / TiO2 catalyst powder. The mass fractions of Pt and Ni were 0.65% and 1.0%, respectively, and the Ni / Pt mass ratio was 1.5.

[0063] PtNi / TiO2 catalyst molding: 2.5g of the above PtNi / TiO2 catalyst powder was mixed evenly with 1.4g of 70% water-soluble phenolic resin and 0.5g of water, and dried in an oven at 120℃ for 2 hours to remove some moisture. The mass ratio of catalyst powder to phenolic resin in the dried product was 2.6. The mixture was manually extruded into strips using a powder press equipped with a 2mm orifice die at an extrusion pressure of 8MPa. The resulting extruded strips were dried overnight in an oven at 160℃ and then carbonized in a tube furnace under nitrogen atmosphere. The carbonization heating program consisted of two stages. The first stage involved heating from room temperature to 425℃ at a heating rate of 10℃ / min; the second stage involved heating from 425℃ to 600℃ at a heating rate of 3℃ / min and holding at that temperature for 4 hours. After the holding period ended and the temperature was lowered to room temperature, the carbonized product was slowly exposed to air to obtain the molded PtNi / TiO2 catalyst.

[0064] Water-gas shift reaction: The above-mentioned shaped PtNi / TiO2 catalyst was used for water-gas shift reaction. The reaction operation was the same as in Example 1. The reaction conditions and results are shown in Table 1.

[0065] Example 5

[0066] Preparation of PtSn / TiO2 catalyst powder: 4.8 mL of stannous chloride aqueous solution with a Sn concentration of 0.025 g / mL was mixed evenly with 3.0 g of titanium dioxide containing both rutile and anatase phases. The mixture was air-dried at room temperature and then dried overnight in an oven at 120 °C. The dried product was calcined in a muffle furnace at 550 °C for 6 h. 0.8 mL of chloroplatinic acid aqueous solution with a Pt concentration of 0.038 g / mL and 3.0 mL of deionized water were mixed evenly with the calcined product. The mixture was air-dried at room temperature and then dried overnight in an oven at 120 °C. The dried product was calcined again in a muffle furnace at 550 °C for 6 h and then reduced in a hydrogen atmosphere tube furnace at 600 °C for 4 h to obtain PtSn / TiO2 catalyst powder, wherein the mass fractions of Pt and Sn were 0.96% and 3.8%, respectively, and the Sn / Pt mass ratio was 4.0.

[0067] PtSn / TiO2 catalyst molding: 2.0g of the above PtSn / TiO2 catalyst powder was mixed evenly with 1.2g of thermoplastic phenolic resin and 1.7g of ethanol, and dried overnight in an oven at 160℃. The mass ratio of catalyst powder to phenolic resin in the dried product was 1.7. The dried product was pressed into ingots using a mold with a diameter of 20mm, under compression conditions of 15MPa for 5min. The resulting ingots were carbonized in a tube furnace under a nitrogen atmosphere. The carbonization heating program consisted of two stages. The first stage involved heating from room temperature to 400℃ at a heating rate of 8℃ / min; the second stage involved heating from 400℃ to 600℃ at a heating rate of 3℃ / min and holding at that temperature for 2h. After the holding period ended and the temperature was lowered to room temperature, the carbonized product was slowly exposed to air to obtain the molded PtSn / TiO2 catalyst.

[0068] Water-gas shift reaction: The above-mentioned shaped PtSn / TiO2 catalyst was used for water-gas shift reaction. The reaction operation was the same as in Example 1. The reaction conditions and results are shown in Table 1.

[0069] After the water-gas shift reaction described in Examples 1-5 is completed, the catalyst is discharged from the reactor. After discharge, each catalyst particle remains intact, hard, and shows no signs of breakage or pulverization.

[0070] Comparative Example 1

[0071] The Pt / TiO2 catalyst powder preparation, catalyst forming, and water-gas shift reaction process described in Example 1 were repeated, but the reduction temperature in the catalyst powder preparation step was changed to 300℃. The reaction results are shown in Table 1.

[0072] The results of Example 1 and Comparative Example 1 show that below the reduction temperature of the catalyst powder provided by this invention, the performance of the obtained catalyst in the water-gas shift reaction decreases sharply. In other words, controlling the reduction temperature of the catalyst powder is a necessary means to ensure the efficient conduction of the water-gas shift reaction.

[0073] Comparative Example 2

[0074] The Pt / TiO2 catalyst powder preparation process described in Example 1 was repeated, but the obtained Pt / TiO2 catalyst powder was directly pressed into ingots using a mold with a diameter of 20 mm. The compression conditions were 25 MPa for 5 min to obtain a shaped Pt / TiO2 catalyst. The shaped Pt / TiO2 catalyst was crushed and sieved, and 20-40 mesh particles were loaded into a fixed-bed reactor. Nitrogen was used to purge the air and test for leaks, and the system pressure was adjusted to the target reaction pressure. Water was introduced into the reactor and the temperature was increased. When the temperature at the center of the bed reached approximately 200°C, the pressure inside the reactor increased sharply. The reaction operation was immediately stopped. After the reactor cooled down, the catalyst was unloaded from the reactor. The catalyst had been completely pulverized into a mud-like substance, clogging the bed.

[0075] The results of Example 1 and Comparative Example 2 show that catalyst particles obtained by conventional compression molding instead of using the catalyst molding method provided by the present invention are easily broken and pulverized under hydrothermal conditions and cannot be used in the multiphase water-gas shift reaction process provided by the present invention.

[0076] Comparative Example 3

[0077] The PdMn / ZrO2 catalyst powder preparation, catalyst forming, and water-gas shift reaction process described in Example 2 were repeated, but the carbonization heating program was changed to a direct increase from room temperature to 550℃ at a heating rate of 10℃ / min and a holding time of 3 hours. The reaction results are shown in Table 1. After the reaction was completed, the catalyst was removed from the reactor. The catalyst was easily crushed by hand.

[0078] The results of Example 2 and Comparative Example 3 indicate that during carbonization, if the "fast-then-slow" staged heating procedure provided by this invention is not used, and the temperature is increased to the final carbonization temperature in one step at a faster rate, the resulting catalyst particles exhibit poor strength under hydrothermal conditions and are not suitable for the multiphase water-gas shift reaction process provided by this invention. This may be because rapid high-temperature carbonization leads to violent gas production, which disrupts the stability of the catalyst composite structure.

[0079] Table 1

[0080]

[0081] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for carrying out a water-gas shift reaction, characterized in that, Includes the following steps: A gaseous reactant containing carbon monoxide is brought into contact with liquid water in a fixed-bed reactor to form a catalyst and react. The volume fraction of carbon monoxide in the gaseous reaction feedstock containing carbon monoxide is ≥30%; The conditions for contacting and reacting the catalyst in the fixed-bed reactor include: a reaction temperature of 200-300℃ and a reaction pressure of 3-7MPa; The molding catalyst was prepared using the following method: (1) Obtain catalyst powder; (2) A mixture containing catalyst powder, phenolic resin and solvent is shaped and then carbonized by programmed temperature rise to form a shaped body, thereby obtaining the shaped catalyst; The conditions for the temperature-heated carbonization process include: The temperature is increased from room temperature to the pre-carbonization temperature at a rate of 5-10℃ / min, and then increased from the pre-carbonization temperature to the final carbonization temperature at a rate of 1-4℃ / min and held for 1-5 hours. The pre-carbonization temperature is 250-450℃, and the final carbonization temperature is 500-750℃.

2. The method according to claim 1, characterized in that, The gas hourly space velocity (GHSV) of the gaseous reactant containing carbon monoxide is 500-2000 h⁻¹. -1 ; The liquid hourly space velocity of the liquid water is 3-15 h⁻¹. -1 ; Preferably, the molar ratio of liquid water to carbon monoxide is 5-10.

3. The method according to claim 1, characterized in that, In step (1), the method for obtaining the catalyst powder includes the following steps: The carrier is mixed with an aqueous solution containing active precious metals, dried, calcined, and then reduced at 350-700℃ for 1-12 hours to obtain catalyst powder.

4. The method according to claim 3, characterized in that, The active noble metal is palladium or platinum; Preferably, the carrier is titanium dioxide or zirconium dioxide.

5. The method according to claim 3, characterized in that, The calcination conditions include: a calcination temperature of 300-600℃ and a calcination time of 4-24h.

6. The method according to claim 3, characterized in that, In step (1), the mass fraction of active noble metals in the catalyst powder, expressed in elemental form, is 0.3%-6%.

7. The method according to claim 1, characterized in that, In step (2), the mass ratio of the catalyst powder to the phenolic resin is 1-3.

8. The method according to claim 1, characterized in that, Step (2) also includes drying, which is performed before and / or after molding.

9. The method according to claim 1, characterized in that, In step (2), the solvent is water or ethanol.

10. The method according to claim 3, characterized in that, In step (1), the carrier and the aqueous solution containing the active noble metal also contain auxiliary metals; The auxiliary metal is one of manganese, iron, nickel, and tin; The mass ratio of auxiliary metals to active precious metals in the catalyst powder, expressed in elemental form, is 0.5-5.

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