CN116212867B

CN116212867B - Water gas shift reaction catalyst, preparation method and application

Info

Publication number: CN116212867B
Application number: CN202111466756.1A
Authority: CN
Inventors: 丛昱; 陈帅; 许国梁; 唐南方; 吴春田; 马玉霞
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2021-12-03
Filing date: 2021-12-03
Publication date: 2024-12-17
Anticipated expiration: 2041-12-03
Also published as: CN116212867A

Abstract

The invention relates to a water gas shift reaction catalyst, a preparation method and application thereof. The water gas shift reaction catalyst provided by the invention comprises Pt/NaNbO ₃-CeO₂, wherein the active component of the catalyst is Pt, the Pt content is 0.5% -10% of the total mass of the catalyst, and the carrier is NaNbO ₃-CeO₂ composite oxide. The active component Pt is introduced by an impregnation method, and the NaNbO ₃-CeO₂ composite oxide carrier is synthesized by a hydrothermal method, wherein the content of NaNbO ₃ is 5% -50% of the total mass of the NaNbO ₃-CeO₂ composite oxide. The catalyst provided by the invention has higher activity and selectivity in the water gas shift reaction, and also has good stability and oxygen impact resistance, and the catalyst provided by the invention does not need reduction before the reaction, is suitable for a fuel cell system which is started quickly and started repeatedly, and has good application prospect.

Description

Water gas shift reaction catalyst, preparation method and application

Technical Field

The invention belongs to the technical field of new energy, and particularly relates to a water gas shift reaction catalyst, a preparation method and application thereof.

Background

With the development of economy, the energy demand is higher and the influence of energy consumption on the environment is increased, and people are eagerly seeking an alternative energy or a cleaner and more efficient fossil energy utilization method. Hydrogen energy is currently recognized as a clean energy source and is considered to be the most promising secondary energy source. Along with the development of hydrogen energy economy, hydrogen fuel cells are becoming an important new energy application platform. The reforming process produces H ₂ with a large amount of CO, whether fossil fuels or ethanol and methanol are used as raw materials. CO has a strong poisoning effect on the electrocatalyst of the fuel cell, so that the fuel cell has a severe limit on the CO content in the hydrogen feedstock, typically below 10ppm. To prevent poisoning of the fuel cell catalyst by CO in a hydrogen fuel cell, the hydrogen fuel is purified by a water gas shift reaction. Therefore, the water gas shift catalyst plays a very important role in the fuel cell, and is a key to commercialization of the hydrogen-supported fuel cell.

The commercial water gas shift reaction is typically carried out in a fixed bed reactor with a catalyst of either Fe ₃O₄-Cr₂O₃ or Cu/ZnO/Al ₂O₃. Fe ₃O₄-Cr₂O₃ is used for the high-temperature water gas shift reaction, the operation temperature is 350-400 ℃, the CO is converted rapidly, but the concentration of the CO cannot be reduced to be very low due to the limitation of thermodynamic equilibrium, and Cu/ZnO/Al ₂O₃ is used for the low-temperature water gas shift reaction, the operation temperature is 200-250 ℃, and the concentration of the CO is further reduced.

Because of the various limitations of conventional water gas shift catalysts in fuel cell applications, the development of new water gas shift catalysts for fuel cell hydrogen production systems has attracted great attention, requiring that new water gas shift catalysts have both high activity and structural stability in both air and cyclic operation. At present, noble metal (such as Pt, au and the like) catalysts supported by various oxide carriers (such as CeO ₂,ZrO₂,TiO₂ and the like) are non-traditional water gas shift catalysts which are researched more at present, and the catalysts have the advantages of (1) high mechanical strength and (2) low sensitivity to poisons such as Cl, S and the like.

K.G.Azzam et al report a Pt/TiO ₂ water gas shift catalyst (APPLIED CATALYSIS A: general,2008,338,66-71) which, although having good initial activity, had poor stability and a 35% decrease in activity after 22h at 300 ℃. Xinsheng Liu et al report a Pt/CeO ₂ catalyst (APPLIED CATALYSIS B: environmental,2005,56,69-75) that has good stability in steady state operation but rapidly decreases in activity after start-stop cycling under feed gas. Wolfgang Ruettinger et al report a Pt/ZrO ₂-CeO₂ catalyst (APPLIED CATALYSIS B: environmental,2006,65,135-141) which has a problem of reduced reaction stability, both in steady state operation and after start-stop cycling, and is not suitable for practical use.

Chinese patent CN108144608a discloses a platinum-based water gas shift catalyst and a method for preparing the same. Concretely, a cerium source solution is dropwise added into a precipitator solution, the solution is continuously stirred and kept at a pH value of about 10, and then a CeO ₂ carrier is obtained through suction filtration, washing, drying and roasting. The platinum source and the cobalt source are loaded on a CeO ₂ carrier by a Co-impregnation method, the content of Pt is 2wt% and the content of Co is 0.1-1wt%. The catalyst prepared by the method is subjected to water vapor shift reaction in typical reformed gas, and has higher activity and stability. Under the same noble metal loading, the addition of Co obviously improves the water vapor shift reaction activity and stability of Pt/CeO ₂.

Chinese patent CN105983427a discloses a Pt/apatite water gas shift reaction catalyst, specifically, hydroxyapatite and halogen substituted apatite are prepared by a coprecipitation method, and platinum is introduced by an impregnation method. The loading of platinum in the catalyst is 0.3% -5% of the total mass of the catalyst. The catalyst prepared by the method performs water vapor shift reaction in typical reformed gas, and shows higher activity than noble metal loaded on a reducible rare earth oxide carrier (CeO ₂) under the same noble metal loading.

Chinese patent CN1674328 discloses a catalyst for water gas shift reaction of carbon monoxide for hydrogen source process of fuel cell, its preparation method and application. The catalyst comprises noble metal/CeO ₂ -transition metal oxide, the loading range of the noble metal is 0.1-3% of the total weight of the catalyst, the mol ratio of the transition metal oxide to CeO ₂ is 1:1-9, and the catalyst has better water gas shift reaction performance.

Chinese patent CN1000429814C discloses a Pt/CeO ₂-ZrO₂ monolithic water gas shift catalyst with a CO conversion of about 30% at 250 ℃ at an airspeed of 10000h ^-1, wang Shudong et al (journal of fuel chemistry, 2008,36,625-630) report a Re/Pt/Ce _0.8Zr_0.2O₂ monolithic catalyst with a CO conversion of about 70% at 250 ℃ at an airspeed of 10000h ^-1.

In summary, although the performance of Pt-based shift catalysts has been greatly improved through many years of research, there are disadvantages in that 1 the catalyst activity is insufficient, especially the activity below 300 ℃ is to be improved, 2 the catalyst has insufficient long-term operation and start-up stability, and 3a new carrier for making the catalyst have higher activity and stability is still needed.

Disclosure of Invention

Based on the current research situation, the invention provides a carbon monoxide water gas shift catalyst, a preparation method and application thereof. The catalyst provided by the invention takes NaNbO ₃-CeO₂ composite oxide as a carrier and Pt as active metal, and has the advantages of high activity, high selectivity and good stability when being used in carbon monoxide water gas shift reaction.

In order to achieve the above purpose, the technical scheme of the invention is as follows:

The first aspect of the invention provides a water gas shift reaction catalyst, wherein the composition of the catalyst is Pt/NaNbO ₃-CeO₂. The active component of the catalyst is Pt, and the content of Pt is 0.5-10% of the total mass of the catalyst, preferably 0.8-8 wt%, and more preferably 1-5wt%. The carrier of the catalyst is NaNbO ₃-CeO₂ composite oxide, and the content of NaNbO ₃ in the carrier is 5-50%, preferably 8-40%, more preferably 10-30% of the total mass of the NaNbO ₃-CeO₂ composite oxide.

The second aspect of the invention provides a preparation method of a Pt/NaNbO ₃-CeO₂ catalyst, which comprises the following steps:

(1) The NaNbO ₃-CeO₂ composite oxide carrier is prepared by dissolving cerium nitrate in deionized water, adding Nb ₂O₅ into cerium nitrate solution, stirring uniformly, adding sodium hydroxide solution into Nb ₂O₅ -cerium nitrate suspension, and stirring vigorously for 1-60 minutes. Transferring the obtained suspension into a hydrothermal kettle, and carrying out hydrothermal reaction for 0.5-24 h at the temperature of 100-220 ℃. After the hydrothermal reaction is finished, the hydrothermal kettle is cooled to room temperature, the obtained solid is filtered, and deionized water is washed to be neutral. And finally, drying the obtained solid for 2-24 hours at the temperature of 60-120 ℃, and performing calcination at the temperature ranging from room temperature to the drying temperature to 300-600 ℃ at the temperature rising rate of 1-20 ℃ per minute for 0.5-10 hours to obtain the NaNbO ₃-CeO₂ composite oxide carrier. The concentration of the cerium nitrate solution is 0.05-1 mol/L, and the concentration of the sodium hydroxide solution is 1-30 mol/L.

(2) The preparation of the catalyst comprises the steps of taking NaNbO ₃-CeO₂ composite oxide solid powder obtained in the step (1) as a carrier, loading soluble salt of active metal platinum on the carrier in an impregnation mode, drying at 60-120 ℃ for 4-24 hours, placing the dried product in an air atmosphere and/or an inert atmosphere, programming the temperature to 300-600 ℃ at a rate of 1-20 ℃ per minute from room temperature to the drying temperature, and roasting for 0.5-10 hours to obtain the Pt/NaNbO ₃-CeO₂ catalyst.

The concentration of the cerium nitrate solution in the step (1) is preferably 0.1-0.8 mol/L, more preferably 0.15-0.5 mol/L, the concentration of the sodium hydroxide solution is preferably 2-25 mol/L, more preferably 5-20 mol/L, the hydrothermal reaction temperature is preferably 140-190 ℃, more preferably 150-180 ℃, the hydrothermal reaction time is preferably 1-10 h, more preferably 2-8 h, the drying temperature of the obtained solid is preferably 70-110 ℃, more preferably 80-100 ℃, the drying time is preferably 2-20 h, more preferably 4-15 h, the temperature is programmed to the baking temperature from room temperature to the drying temperature, the heating rate is preferably 3-10 ℃ per min, more preferably 5-8 ℃ per min, the baking temperature is preferably 350-550 ℃, the baking time is preferably 400-500 ℃, and the baking time is preferably 1-8 h, more preferably 2-4 h.

In the step (2), the soluble salt of platinum is one or more of chloroplatinic acid, platinum chloride, platinum nitrate, tetra-ammine platinum dichloride, tetra-ammine platinum nitrate, tetra-ammine platinum acetate or platinum acetylacetonate, the drying temperature of the catalyst is preferably 70-110 ℃, more preferably 80-100 ℃, the drying time is preferably 2-20 hours, more preferably 4-15 hours, the temperature is programmed to be raised to a roasting temperature from room temperature to the drying temperature, the heating rate is preferably 3-10 ℃ per minute, more preferably 5-8 ℃ per minute, the roasting temperature is preferably 350-550 ℃, more preferably 400-500 ℃, and the roasting time is preferably 1-8 hours, more preferably 2-4 hours.

In a third aspect, the invention provides the use of a Pt/NaNbO ₃-CeO₂ catalyst for carbon monoxide water gas shift reactions. The catalyst does not need to be reduced in advance in the application to the water gas shift reaction. The water gas shift reaction conditions are that water and CO are necessary components in the reaction gas, the molar ratio of water to CO is (2.0-12): 1, preferably (2.5-10): 1, more preferably (3-8): 1, the reaction gas contains no or unnecessary components, the unnecessary components are one or more of N ₂、CO₂、H₂, ar and He, the mole fraction of the unnecessary components in the reaction gas is 0-90%, the space velocity of the reaction raw material passing through the catalyst bed layer is 5000-500000ml.h ^-1·g^-1 _Catalyst, preferably 10000-400000ml.h ^-1·g^-1 _Catalyst, more preferably 20000-300000ml.h ^-1·g^-1 _Catalyst, the pressure of the reaction system is 0.1-4 MPa, preferably 0.1-2 MPa, more preferably 0.1-1 MPa, and the reaction temperature is 200-550 ℃, preferably 225-450 ℃, more preferably 250-450 ℃.

The flow of the reaction evaluation device for verifying the technical scheme of the invention is shown in figure 1. Feed gas ① is metered by flow meter ② into preheater ⑤ and water ③ is metered into preheater ⑤ by metering pump ④. The mixture is preheated to 100-400 ℃ in a preheater ⑤, the preheated mixture enters a reactor ⑦ arranged in a heating area of a reaction furnace ⑥, a constant temperature area of the reactor ⑦ is provided with a catalyst bed ⑧, the reacted mixture is separated into a gas phase product and condensed water after passing through a condenser ⑨, the condensed water is discharged by a stop valve ⑩ at proper time, and the gas phase product passes through a back pressure valveAfter the pressure is reduced to normal pressure, the gas is passed through a gas flowmeterEmptying after metering, and emptying the pipelineThe sampling branch is arranged on the gas supply phase chromatographAnd (5) sampling and analyzing.

Compared with the traditional high-temperature shift and low-temperature shift catalysts, the invention has the following advantages:

(1) The Pt/NaNbO ₃-CeO₂ catalyst provided by the invention is prepared by adopting a hydrothermal method and an impregnation method, and has the advantages of simple preparation method, maturity and good repeatability.

(2) The Pt/NaNbO ₃-CeO₂ catalyst provided by the invention has the advantages that in the hydrothermal treatment process, naNbO ₃ is formed to be beneficial to the generation of oxygen defects, and the concentration of Ce ³⁺ on the surface of CeO ₂ in the composite oxide is greatly increased, so that the water gas shift reaction activity of the catalyst is improved.

(3) The Pt/NaNbO ₃-CeO₂ catalyst provided by the invention has the advantages of high activity, high selectivity, good stability and high airspeed operation resistance in the water gas shift reaction.

(4) The Pt/NaNbO ₃-CeO₂ catalyst provided by the invention does not need reduction operation before use, is resistant to air oxidation, can adapt to the application environment of quick start and repeated start and stop of a fuel cell system, overcomes various limitations of the traditional shift catalyst under an unsteady state condition, and has a wide application prospect.

Drawings

FIG. 1 is a schematic flow diagram of a CO water gas shift reaction evaluation device;

① CO feed gas, ② flow meter, ③ water, ④ metering pump, ⑤ preheater, ⑥ reactor, ⑦ reactor, ⑧ catalyst bed, ⑨ condenser, ⑩ shut-off valve, The back pressure valve is provided with a valve,A gas flow meter is provided which,A gas chromatograph,And (5) emptying the pipeline.

Fig. 2 shows XRD patterns of the catalyst supports prepared in examples 1 to 4, comparative example 1, and comparative example 2.

Fig. 3 shows XRD patterns of the catalysts prepared in examples 1 to 4, comparative example 1 and comparative example 2.

FIG. 4 shows the water gas shift reaction test data obtained in examples 12 to 15.

FIG. 5 shows water gas shift reaction test data obtained in examples 12 and examples 16 to 19

FIG. 6 shows the water gas shift reaction test data obtained in examples 12 and 20.

FIG. 7 is water gas shift reaction test data for the catalyst obtained in example 21 at various space velocities.

FIG. 8 is the catalyst stability test data obtained in example 22.

FIG. 9 shows the oxygen impact stability test data of the catalyst obtained in example 23.

FIG. 10 shows water gas shift reaction test data obtained in example 12 and comparative examples 3 to 6.

Detailed Description

The present invention will be further described with reference to the following specific examples, but the present invention is not limited to these specific examples.

Example 1

(1) 5.05G of cerium nitrate hexahydrate is weighed and dissolved in 30mL of deionized water, then 0.6307g of Nb ₂O₅ is weighed and added into cerium nitrate solution, and the mixture is stirred vigorously and uniformly, then 40mL of prepared 5mol/L sodium hydroxide solution is added into Nb ₂O₅ -cerium nitrate suspension, and the mixture is stirred vigorously for 30 minutes. The resulting suspension was transferred to a 100ml hydrothermal kettle and reacted hydrothermally at 150 ℃ for 2h. After the hydrothermal reaction is finished, the hydrothermal kettle is cooled to room temperature, the obtained solid is filtered, and the solid is washed to be neutral by deionized water. The obtained solid was dried at 80℃for 4 hours, and finally, the obtained solid was calcined at a rate of 5℃/min from room temperature to a drying temperature and then programmed to 400℃for 2 hours, to obtain 28wt% NaNbO ₃-CeO₂ composite oxide support, the XRD pattern of which was shown in FIG. 2. The result shows that the XRD pattern is mainly NaNbO ₃、CeO₂ diffraction peak, which shows that the obtained substance is NaNbO ₃-CeO₂ composite oxide.

(2) Weighing 1.0g of the 28wt% NaNbO ₃-CeO₂ composite oxide solid powder obtained in the step (1), weighing 0.0265g of chloroplatinic acid, dissolving in 1ml of deionized water to obtain an impregnating solution, adding the impregnating solution into a NaNbO ₃-CeO₂ composite oxide carrier, uniformly stirring, drying at 80 ℃ for 2h, placing the dried product in an air atmosphere, programming the temperature to 400 ℃ from room temperature to the drying temperature at a rate of 5 ℃ per minute, and roasting for 2h, wherein the obtained catalyst is expressed as 1Pt/28wt% NaNbO ₃-CeO₂, and the XRD pattern is shown in figure 3. The result shows that the diffraction peak of the active metal platinum is not seen in the XRD pattern, which indicates that the active metal is uniformly distributed on the composite oxide carrier.

Example 2:

The procedure of example 1 was repeated except that Nb ₂O₅ was added in an amount of 0.0854g in step (1), and the resulting catalyst was 1Pt/5wt% NaNbO ₃-CeO₂, the XRD pattern of the support was shown in FIG. 2, and the XRD pattern of the catalyst was shown in FIG. 3. The diffraction peak of the carrier XRD pattern is mainly CeO ₂, the diffraction peak of NaNbO ₃ is not seen, the NaNbO ₃ is uniformly dispersed in CeO ₂, the diffraction peak of the active metal platinum is not seen in the catalyst XRD pattern, and the active metal is uniformly distributed on the composite oxide carrier.

Example 3:

The procedure of example 1 was repeated except that Nb ₂O₅ was added in an amount of 0.2640g in step (1), and the resulting catalyst was 1Pt/14wt% NaNbO ₃-CeO₂, the XRD pattern of the support was shown in FIG. 2, and the XRD pattern of the catalyst was shown in FIG. 3. The diffraction peak of the carrier XRD pattern is mainly CeO ₂, the diffraction peak of NaNbO ₃ is not seen, the NaNbO ₃ is uniformly dispersed in CeO ₂, the diffraction peak of the active metal platinum is not seen in the catalyst XRD pattern, and the active metal is uniformly distributed on the composite oxide carrier.

Example 4:

The procedure of example 1 was repeated except that Nb ₂O₅ was added in an amount of 1.6219g in step (1), and the resulting catalyst was 1Pt/50wt% NaNbO ₃-CeO₂, the XRD pattern of the support was shown in FIG. 2, and the XRD pattern of the catalyst was shown in FIG. 3. The diffraction peak of NaNbO ₃、CeO₂ is shown in the XRD graph of the carrier, the intensity of the diffraction peak of NaNbO ₃ is obviously stronger than that of 28wt% NaNbO ₃-CeO₂, and the diffraction peak of active metal platinum is not shown in the XRD graph of the catalyst, so that the active metal is uniformly distributed on the composite oxide carrier.

Example 5:

The procedure of example 1 was repeated except that chloroplatinic acid was added in an amount of 0.0530g in step (2), and the resulting catalyst was 2Pt/28wt% NaNbO ₃-CeO₂.

Example 6:

The procedure of example 1 was repeated except that chloroplatinic acid was added in an amount of 0.1325g in step (2), and 5Pt/28wt% NaNbO ₃-CeO₂ was obtained as a final catalyst.

Example 7:

the procedure of example 1 was repeated except that chloroplatinic acid was added in an amount of 0.2650g in step (2), and 10Pt/28wt% NaNbO ₃-CeO₂ was obtained as a final catalyst.

Example 8:

The procedure of example 1 was repeated except that chloroplatinic acid was added in an amount of 0.0133g in step (2), and the resulting catalyst was 0.5Pt/28wt% NaNbO ₃-CeO₂.

Example 9:

The procedure of example 1 was repeated except that the hydrothermal reaction temperature in step (1) was 160℃and the hydrothermal reaction time was 18 hours, and the resulting catalyst was 1Pt/28wt% NaNbO ₃-CeO₂ -160℃to 18 hours.

Example 10:

The procedure of example 1 was repeated except that in step (1), the concentration of sodium hydroxide was 10mol/L, the hydrothermal reaction temperature was 100℃and the hydrothermal reaction time was 24 hours, the drying time was 60℃and the drying time was 24 hours, the firing temperature-raising rate was 1℃per minute, the firing temperature was 300℃and the firing time was 10 hours. In the step (2), the drying time temperature is 60 ℃, the drying time is 24 hours, the roasting heating rate is 1 ℃ per minute, the roasting temperature is 300 ℃, and the roasting time is 10 hours. The final catalyst was 1Pt/28wt% NaNbO ₃-CeO₂ -100℃for 24h.

Example 11:

The procedure of example 1 was repeated except that in step (1), the concentration of sodium hydroxide was 30mol/L, the hydrothermal reaction temperature was 220℃and the hydrothermal reaction time was 0.5h, the drying time temperature was 120℃and the drying time was 2h, the firing temperature-raising rate was 20℃per minute, the firing temperature was 600℃and the firing time was 0.5h. In the step (2), the drying time temperature is 120 ℃, the drying time is 2 hours, the roasting heating rate is 20 ℃ per minute, the roasting temperature is 600 ℃, and the roasting time is 0.5 hour. The final catalyst was 1Pt/28wt% NaNbO ₃-CeO₂ -220℃for 0.5h.

Example 12:

CO water gas shift reaction evaluation:

The catalyst of example 1 was tabletted and pelletized with 1Pt/28wt% NaNbO ₃-CeO₂, and then 0.2g (40-60 mesh) was placed in a micro fixed bed reactor as shown in FIG. 1 for water gas shift reaction evaluation. The composition of the reaction raw material gas is 40% H ₂/15％CO/13％CO₂/32% Ar (volume ratio), the molar ratio of water to CO is 3, the feeding flow rate of the mixed gas is 230ml min ^-1, the mass space velocity (WHSV) converted into the feed is about 100000ml h ^-1·g^-1 _Catalyst, the reaction pressure is 0.1MPa, the reaction temperatures are respectively 200 ℃, 250 ℃, 275 ℃, 300 ℃, 325 ℃, 350 ℃, 400 ℃ and 550 ℃, and the reaction is carried out for 30min at each temperature, and the specific result is shown in figure 4.

Example 13:

The procedure of example 12 was repeated except that the catalyst used was 1Pt/5wt% NaNbO ₃-CeO₂ as prepared in example 2, and the specific results are shown in FIG. 4.

Example 14:

The procedure of example 12 was repeated except that the catalyst used was 1Pt/14wt% NaNbO ₃-CeO₂ as the catalyst prepared in example 3, and the specific results are shown in FIG. 4.

Example 15:

the procedure of example 12 was repeated except that the catalyst used was 1Pt/50wt% NaNbO ₃-CeO₂ as prepared in example 4, and the specific results are shown in FIG. 4.

Example 16:

The procedure of example 12 was repeated except that the catalyst used was 2Pt/28wt% NaNbO ₃-CeO₂ as prepared in example 5, and the specific results are shown in FIG. 5.

Example 17:

The procedure of example 12 was repeated except that the catalyst used was 5Pt/28wt% NaNbO ₃-CeO₂ as the catalyst prepared in example 6, and the specific results are shown in FIG. 5.

Example 18:

Example 12 was repeated except that the catalyst used was 10Pt/28wt% NaNbO ₃-CeO₂ as prepared in example 7, and the specific results are shown in FIG. 5.

Example 19:

The procedure of example 12 was repeated except that the catalyst used was 0.5Pt/28wt% NaNbO ₃-CeO₂ as the catalyst prepared in example 8, and the specific results are shown in FIG. 5.

Example 20:

The procedure of example 12 was repeated except that the catalyst used was 1Pt/28wt% NaNbO ₃-CeO₂ -160℃to 18h as prepared in example 9, and the specific results are shown in FIG. 6.

Example 21:

The procedure of example 12 was repeated except that the reaction temperature was fixed at 400℃and the feed flow rate of the reaction mixture was adjusted, and the activities of the 1Pt/28wt% NaNbO ₃-CeO₂ catalyst at different space velocities as measured by mass space velocity (WHSV) of the feed at 400℃were examined by 5000ml·h^-1·g^-1 _Catalyst、100000ml·h^-1·g^-1 _Catalyst、200000ml·h^-1·g^-1 _Catalyst、300000ml·h^-1·g^-1 _Catalyst、500000ml·h^-1·g^-1 _Catalyst,, respectively, as shown in FIG. 7.

Example 22:

The procedure of example 12 was repeated except that the reaction temperature was set at 400℃and the space velocity (WHSV) was set at 200000 ml.multidot.h ^-1·g^-1 _Catalyst, and the analysis results were sampled every 1 hour, and the stability of 1Pt/28wt% NaNbO ₃-CeO₂ catalyst was examined for 100 hours, as shown in FIG. 8.

Example 23:

The procedure of example 12 was repeated except that the reaction temperature was set at 400℃and the space velocity (WHSV) was set at 200000 ml.multidot.h ^-1·g^-1 _Catalyst, and the analysis result was sampled after 30 minutes of reaction. Then stopping the reaction, switching the raw material gas into air, keeping the temperature of the reactor at 400 ℃ for 30min, then performing activity evaluation, repeating the process for 10 times, and examining the oxygen impact resistance of the catalyst, wherein the specific result is shown in fig. 9.

Example 24:

the procedure of example 12 was repeated, except that the molar ratio of water to CO was adjusted to 2:1 and the pressure was adjusted to 4MPa.

Example 25:

The procedure of example 12 was repeated, except that the molar ratio of water to CO was adjusted to 12:1.

Comparative example 1

The procedure of example 1 was repeated except that Nb ₂O₅ was not added in step (1), the resulting catalyst was 1Pt/CeO ₂, the XRD pattern of the support CeO ₂ was shown in FIG. 2, and the XRD pattern of the catalyst 1Pt/CeO ₂ was shown in FIG. 3. The result shows that the diffraction peak in the carrier XRD pattern is CeO ₂ diffraction peak, and the diffraction peak of the active metal platinum is not seen in the catalyst XRD pattern, which shows that the platinum is uniformly dispersed on the carrier CeO ₂.

Comparative example 2

The procedure of example 1 was repeated except that cerium nitrate was not added in step (1), the resulting catalyst was 1Pt/NaNbO ₃, the XRD pattern of the support NaNbO ₃ was shown in FIG. 2, and the XRD pattern of the catalyst 1Pt/NaNbO ₃ was shown in FIG. 3. The result shows that the diffraction peak in the carrier XRD pattern is NaNbO ₃ diffraction peak, and the diffraction peak of active metal platinum is not seen in the catalyst XRD pattern, which shows that platinum is uniformly dispersed on the carrier NaNbO ₃.

Comparative example 3

The procedure of example 12 was repeated except that the catalyst used was 1Pt/CeO ₂ as the catalyst prepared in comparative example 1, and the specific results are shown in FIG. 10.

Comparative example 4

The procedure of example 12 was repeated except that the catalyst used was catalyst 1Pt/NaNbO ₃ prepared in comparative example 1, and the specific results are shown in FIG. 10.

Comparative example 5

The procedure of example 12 was repeated except that the catalyst used was a Fe ₃O₄-Cr₂O₃ industrial high-temperature shift catalyst, and the result is shown in FIG. 10.

Comparative example 6

The procedure of example 12 was repeated except that the catalyst used was a Cu/ZnO/Al ₂O₃ industrial low temperature shift catalyst, and the results are shown in FIG. 10.

The application test result shows that the Pt/NaNbO ₃-CeO₂ catalyst provided by the invention has excellent water gas shift reaction catalytic performance, wherein (1) the 1Pt/28wt% NaNbO ₃-CeO₂ catalyst has the molar ratio of water to CO of 3:1 in a simulated atmosphere of 40% H ₂/15％CO/13％CO₂/32% Ar, the CO conversion rate is close to the equilibrium conversion rate at 300 ℃ under the condition that the airspeed is 100000 ml.h ^-1·g^-1 _Catalyst, and the activity is far higher than that of the Pt/CeO ₂ water gas shift catalyst. (2) The 1Pt/28wt% NaNbO ₃-CeO₂ catalyst has good stability, and the CO conversion rate is always maintained to be more than 75% within 100 hours under the conditions that the molar ratio of water to CO is 3:1, the reaction temperature is 400 ℃ and the airspeed is 200000 ml.multidot.h ^-1·g^-1 _Catalyst in a simulated atmosphere of 40% H ₂/15％CO/13％CO₂/32% Ar, so that the equilibrium conversion rate is close. (3) The 1Pt/28wt% NaNbO ₃-CeO₂ catalyst has good performance at high space velocity, the molar ratio of water to CO is 3:1 in a simulated atmosphere of 40% H ₂/15％CO/13％CO₂/32% Ar, and the CO conversion rate can still exceed 70% at 400 ℃ under the condition that the space velocity is up to 500000 ml.multidot.h ^-1·g^-1 _Catalyst, which indicates that the catalyst is suitable for high space velocity operation. (4) As can be seen from FIG. 9, the 1Pt/28wt% NaNbO ₃-CeO₂ catalyst has excellent oxygen impact resistance, and is suitable for the application environment of repeated start-up and stop of a fuel cell system. (5) As can be seen from FIG. 10, the activity of 1Pt/28wt% NaNbO ₃-CeO₂ is much higher than that of the conventional Fe ₃O₄-Cr₂O₃ high temperature shift and Cu/ZnO/Al ₂O₃ low temperature shift catalysts, and also much higher than that of the Pt/CeO ₂ catalysts.

The foregoing description is only of the preferred embodiments of the invention and is not intended to limit the invention thereto. Various modifications of the invention will be apparent to those skilled in the art. Any modification, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A water-gas shift reaction catalyst, characterized in that: the catalyst composition is Pt/NaNbO ₃ -CeO ₂ ; the active component of the catalyst is Pt, and the Pt content is 0.5% to 10% of the total mass of the catalyst; the carrier of the catalyst is NaNbO ₃ -CeO ₂ composite oxide, and the NaNbO ₃ content in the carrier is 5% to 50% of the total mass of the NaNbO ₃ -CeO ₂ composite oxide.

2. The water-gas shift reaction catalyst according to claim 1, characterized in that: the content of the active component Pt of the catalyst is 0.8~8wt%; the content of _NaNbO3 in the carrier of the catalyst is 8~40wt%.

3. The water-gas shift reaction catalyst according to claim 1, characterized in that: the content of the active component Pt of the catalyst is 1-5wt%; and the content of NaNbO ₃ in the carrier of the catalyst is 10-30wt%.

4. A method for preparing the catalyst according to any one of claims 1 to 3, characterized in that it comprises the following steps:

(1) Preparation of NaNbO ₃ -CeO ₂ composite oxide support: dissolve cerium nitrate in water, then add Nb ₂ O ₅ to the cerium nitrate solution and stir evenly; then add sodium hydroxide solution to the Nb ₂ O ₅ -cerium nitrate suspension and stir for 1-60 minutes; transfer the obtained suspension to a hydrothermal reactor and perform a hydrothermal reaction at 100-220 °C for 0.5-24 h; after the hydrothermal reaction, cool the hydrothermal reactor to room temperature, filter the obtained solid, and wash it with deionized water until it is neutral; finally, dry the obtained solid at 60-120 °C for 2-24 h; program the temperature from room temperature to the drying temperature to 300-600 °C at a rate of 1-20 °C/min, and calcine for 0.5-10 h to obtain a NaNbO ₃ -CeO ₂ composite oxide support; the concentration of the cerium nitrate solution is 0.05-1 mol/L, and the concentration of the sodium hydroxide solution is 1-30 mol/L;

(2) Catalyst preparation: The soluble salt of active metal platinum is loaded onto the NaNbO ₃ -CeO ₂ composite oxide carrier obtained in step (1) by impregnation, and dried at 60-120 °C for 4-24 h; the dried product is placed in an air atmosphere and/or an inert atmosphere, and the temperature is programmed to rise from room temperature to the drying temperature to 300-600 °C at a rate of 1-20 °C/min, and calcined for 0.5-10 h to obtain a Pt/NaNbO ₃ -CeO ₂ catalyst.

5. The method for preparing the catalyst according to claim 4, characterized in that:

The concentration of the cerium nitrate solution in step (1) is 0.1-0.8 mol/L; the concentration of the sodium hydroxide solution is 2-25 mol/L; the sodium hydroxide solution is added to the _Nb2O5 - _cerium nitrate suspension and stirred for 5-50 minutes; the hydrothermal reaction temperature is 140-190°C; the hydrothermal reaction time is 1-10 h; the drying temperature is 70-110°C, and the drying time is 2-20 h; the temperature is programmed from room temperature to the drying temperature to the roasting temperature, the heating rate is 3-10°C/min, the roasting temperature is 350-550°C, and the roasting time is 1-8 h;

In the step (2), the soluble salt of platinum is one or more of chloroplatinic acid, platinum chloride, platinum nitrate, tetraamine platinum dichloride, tetraamine platinum nitrate, tetraamine platinum acetate or platinum acetylacetonate; the drying temperature is 70-110°C, and the drying time is 2-20 h; the temperature is programmed from room temperature to the drying temperature to the roasting temperature, the heating rate is 3-10°C/min, the roasting temperature is 350-550°C, and the roasting time is 1-8 h.

6. The method for preparing the catalyst according to claim 4, characterized in that:

The concentration of the cerium nitrate solution in step (1) is 0.15-0.5 mol/L; the concentration of the sodium hydroxide solution is 5-20 mol/L; the sodium hydroxide solution is added to the _Nb2O5 - _cerium nitrate suspension and stirred for 15-40 minutes; the hydrothermal reaction temperature is 150-180°C; the hydrothermal reaction time is 2-8 h; the drying temperature is 80-100°C, and the drying time is 4-15 h; the temperature is programmed from room temperature to the drying temperature to the roasting temperature, the heating rate is 5-8°C/min, the roasting temperature is 400-500°C, and the roasting time is 2-4 h;

The drying temperature in step (2) is 80-100°C; the drying time is 4-15h; the temperature is raised from room temperature to the drying temperature to the calcination temperature at a heating rate of 5-8°C/min; the calcination temperature is 400-500°C; and the calcination time is 2-4h.

7. Use of the catalyst according to any one of claims 1 to 3, characterized in that the catalyst is used for water-gas shift reaction.

8. The use according to claim 7, characterized in that: the catalyst is suitable for water-gas shift reaction conditions: the reaction temperature is 200-550°C, water and CO are essential components in the reaction gas, and the molar ratio of water to CO is (2-12):1; the reaction gas does not contain or contains non-essential components, the non-essential components are one or more of _N2 , _CO2 , _H2 , Ar, and He, and the molar fraction of the non-essential components in the reaction gas is 0-90%; the space velocity of the reaction raw materials passing through the catalyst bed is 5000-500000ml·h ^-1 ·g ^-1 _catalyst ; the pressure of the reaction system is 0.1-4 MPa.

9. The use according to claim 8, characterized in that: the molar ratio of water to CO is (2.5~10):1; the reaction temperature is 225~500°C; the space velocity of the reaction raw materials through the catalyst bed is 10000~400000 ml·h ^-1 ·g ^- _1catalyst ; and the pressure of the reaction system is 0.1~2 MPa.

10. The use according to claim 8, characterized in that: the molar ratio of water to CO is (3-8):1; the reaction temperature is 250-450°C; the space velocity of the reaction raw materials through the catalyst bed is 20000-300000 ml·h ^-1 ·g ^-1 _catalyst ; the pressure of the reaction system is 0.1-1 MPa;

The catalyst does not need to be reduced before catalyzing the reaction.