Methane steam reforming catalyst, method for preparing the same, and method for producing hydrogen by methane steam reforming

Abstract

The application relates to the field of catalysts, and discloses a methane steam reforming catalyst, a preparation method thereof, and a hydrogen production method through methane steam reforming. The catalyst comprises a carrier, an active metal component and an auxiliary component supported on the carrier; the active metal component is Ni, and the auxiliary component is selected from at least one of rare earth metals; the average grain size of the active metal component is 3-12 nm, the content of the carrier is 72-94 wt% based on the total amount of the catalyst, the content of the active metal component is 5.9-18 wt% based on the oxide, and the content of the auxiliary component is 0.1-10 wt%. The catalyst has higher metal content and smaller grain size of the active metal component, and thus has higher reaction activity and carbon deposition resistance. The finished catalyst does not deactivate after continuous stable operation for 2000 hours under laboratory conditions, and has the feasibility of industrial application.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalysts, in particular to a methane steam reforming catalyst, a preparation method thereof and a method for hydrogen production by methane steam reforming. BACKGROUND

[0002] In the chemical industry, the largest amount of hydrogen is used for synthesis of ammonia and petroleum refining, and hydrogen is also required in other fields, such as metallurgy, electronics, glass, medicine, food, aerospace, energy, etc. On the one hand, in recent years, with the increase in demand for hydrogen in hydrogen reforming and hydrogenation cracking reactions in the oil refining process and the increasing demand for hydrogen in the petrochemical industry, such as synthesis of ammonia, synthetic gasoline, synthetic methanol, Fischer-Tropsch synthesis, etc., the technology for hydrogen production by steam conversion of methane, naphtha and heavy oil and coal gasification has received more attention. In particular, the degree of attention to environmental quality is increasing, and the sulfur content index in fuel gas emissions is decreasing, while the degree of oil refining is continuously deepening, which also increases the demand for hydrogen. On the other hand, hydrogen is a clean fuel with high combustion heat value and water as the product, and does not produce a large amount of greenhouse gases such as CO2 and pollution gases such as SO x , NO x , etc., so the demand for clean fuels is also increasing.

[0003] Natural gas will be the main raw material for the preparation of synthesis gas and thus hydrogen, due to its abundant reserves. Although coal has a larger reserve and is cheaper, its investment is three times that of a synthesis gas plant using natural gas as the raw material. Therefore, in the future, the natural gas reforming process for hydrogen production will still be the most important way of hydrogen production worldwide.

[0004] At present, the natural gas hydrogen production process is very mature, but its most significant disadvantage is high energy consumption, which significantly increases the production cost of hydrogen. In order to reduce the energy consumption of the process, reducing the steam-to-carbon ratio is a feasible path. Foreign hydrogen production technology companies have attempted to do so, such as the Brown process in the United States, the AMV process of ICI Company, the LCA process, etc. In order to adapt to the requirements of new processes, high-efficiency catalysts corresponding to the new processes must be developed. In addition to the various properties of conventional natural gas steam reforming catalysts, such catalysts must also have higher activity and stronger carbon deposition resistance, so as to be able to operate continuously and stably for a long period at a low steam-to-carbon ratio.

[0005] The energy-saving methane steam reforming catalysts for hydrogen production developed at home and abroad at present are mostly prepared by impregnation, and the commonly used hydrogen production catalyst carriers are mostly α-Al2O3, CaO-Al2O3 or MgO-Al2O3 prepared by high-temperature sintering. Although such high-temperature sintering type carriers have high strength, the water absorption rate is relatively low, and when they are used for loading active metals by impregnation, a high-concentration nickel nitrate solution needs to be prepared and heated, and generally two or three impregnations are required to achieve the required metal loading. SUMMARY

[0006] The present application aims to overcome the problems of large grain size of active metal component in the catalyst, low catalyst activity, poor carbon deposition resistance, long preparation process in the prior art, and provides a methane steam reforming catalyst, a preparation method thereof and a hydrogen production method by methane steam reforming, which has high catalytic activity, good carbon deposition resistance and high stability.

[0007] To achieve the above-mentioned purpose, the first aspect of the present application provides a methane steam reforming catalyst, which comprises a carrier and active metal component and auxiliary component supported on the carrier; wherein the active metal component is Ni, and the auxiliary component is selected from at least one of rare earth metals; wherein the average particle size of the active metal component is 3-12 nm, the content of the carrier is 72-94 wt% based on the total amount of the catalyst, the content of the active metal component is 5.9-18 wt% based on the oxide, and the content of the auxiliary component is 0.1-10 wt%.

[0008] The second aspect of the present application provides a preparation method of the methane steam reforming catalyst, which comprises: contacting a carrier loaded with an organic adsorbent with an impregnation solution, and then performing first drying and calcination.

[0009] The impregnation solution contains soluble compounds of the active metal component and the auxiliary component, the active metal component is Ni, and the auxiliary component is selected from at least one of rare earth metals; the use amount of the carrier and the impregnation solution is such that the content of the carrier in the prepared catalyst is 81-91 wt%, the content of the active metal component is 5.9-18 wt% based on the oxide, and the content of the auxiliary component is 0.1-10 wt%.

[0010] The third aspect of the present application provides the methane steam reforming catalyst prepared by the above-mentioned preparation method.

[0011] The fourth aspect of the present application provides a hydrogen production method by methane steam reforming, which comprises: contacting methane and water with a catalyst under the conditions of hydrogen production by methane steam reforming, and the catalyst is the methane steam reforming catalyst provided in the first aspect or the third aspect.

[0012] The inventors found in the research that, in the prior art, in order to pursue high loading of the target, it is often necessary to use a high concentration of impregnation liquid and to be subjected to multiple calcinations, so that the crystal grains of the active metal component are too large, and the activity of the catalyst is difficult to reach the expectation. Therefore, the catalyst in the prior art is difficult to balance the high metal loading and the small crystal grain size of the active metal component. The methane steam reforming catalyst provided by the present application can balance the high metal loading and the small crystal grain size of the active metal component, and thus has higher reaction activity and carbon deposition resistance. The finished catalyst does not lose activity after continuous stable operation for 2000 hours under laboratory conditions, and has the feasibility of industrial application. Meanwhile, the catalyst preparation method provided by the present application has a simple production process, and the one-step impregnation can meet the active metal component loading requirement of the target, so as to ensure that the crystal grain size of NiO in the obtained catalyst is small, the operation is convenient, and the catalyst production cost is greatly saved. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is the XRD spectrum of the catalyst obtained in Example 1 and Comparative Example 1;

[0014] Figure 2 is the long-period reaction stability evaluation result of the catalyst obtained in Example 1. DETAILED DESCRIPTION

[0015] The endpoints of the ranges and any values claimed herein are not to be understood as limited to the exact values recited as implicitly split into a narrower range between each pair of endpoints. The ranges or values should be interpreted as being approximate, as encompassing values near the recited values within a range given, and as being endpoints and individual points. For values which are reportedly less than or greater than a specific value, this is intended to encompass values which are next higher or next lower than the recited value as well as the value recited.

[0016] The first aspect of the present application provides a methane steam reforming catalyst, which comprises a carrier and an active metal component and an auxiliary component supported on the carrier; wherein the active metal component is Ni, and the auxiliary component is selected from at least one of rare earth metals; wherein the average crystal grain size of the active metal component is 3-12 nm, the content of the carrier is 72-94 wt% based on the total amount of the catalyst, the content of the active metal component is 5.9-18 wt% based on the oxide, and the content of the auxiliary component is 0.1-10 wt%.

[0017] Compared with the methane steam reforming catalyst in the prior art, the active metal component in the catalyst has a smaller crystal grain size, and thus has higher reaction activity and carbon deposition resistance. The finished catalyst does not lose activity after continuous stable operation for 2000 hours under laboratory conditions, and has the feasibility of industrial application.

[0018] According to the present application, preferably, the average grain size of the active metal component is 4-9 nm. In the above preferred case, the catalytic activity and the anti-carbon deposition performance are improved.

[0019] In the present application, the average grain size of the active metal component can be tested by XRD method and calculated according to Scherrer formula.

[0020] According to the present application, preferably, the content of the carrier is 81-91 wt%, the content of the active metal component is 8-14 wt% and the content of the auxiliary component is 1-5 wt% based on the total amount of the catalyst. In the above preferred composition, the activity and stability of the catalyst are further improved.

[0021] It can be understood that when the catalyst only contains the carrier, the active metal component and the auxiliary component, the total content of the carrier, the active metal component and the auxiliary component adds up to 100%.

[0022] In the present application, the content of each component is measured by fluorescence analysis method.

[0023] In the present application, the carrier can be selected from the conventional ones in the art, and can be commercially available or prepared by the known preparation method in the art. For example, the carrier can be an oxide carrier prepared by high-temperature sintering method, preferably, the carrier can be at least one of α-Al2O3, MgO-Al2O3, CaO-Al2O3, SiC and BN, more preferably, α-Al2O3. When α-Al2O3 is used as the carrier, the catalytic reaction activity and the anti-carbon deposition performance of the catalyst are further improved.

[0024] Preferably, the water absorption rate of the carrier is 0.18-0.25%.

[0025] The inventors have found in the research that for the high-temperature sintering type carrier, since the water absorption rate of this type of carrier is relatively low, multiple impregnations are required to ensure the target metal loading amount. After the active metal component is loaded by the conventional impregnation method, the average particle size of the active metal component is relatively large, thereby resulting in low catalytic activity and poor anti-carbon deposition performance. However, the catalyst provided by the present application still has a suitable grain size of the active metal component when the high-temperature sintering type carrier is used, which is beneficial to improve the catalytic activity of the catalyst.

[0026] In the present application, the rare earth metal refers to 17 elements in total in the group IIIB of the periodic table, i.e. the lanthanide series and the elements similar to the lanthanide series in chemical properties, i.e. scandium and yttrium. Preferably, the auxiliary component is selected from at least one of La, Ce, Pr and Sm, preferably La and / or Ce. The use of the above auxiliary component is beneficial to improve the dispersion of the active metal and the anti-carbon deposition performance.

[0027] According to the present application, preferably, the mole ratio of the soluble compound of the active metal component to the soluble compound of the promoter component is 0.03-0.2:1, preferably 0.04-0.15:1, on an elemental basis. With the above preferred composition, the combination of the active metal component and the promoter component helps to improve the activity and stability of the catalyst.

[0028] The second aspect of the present application provides a method for preparing a catalyst for steam reforming of methane, which comprises: contacting a carrier loaded with an organic adsorbent with an impregnation solution, and then performing first drying and calcination;

[0029] The impregnation solution contains a soluble compound of an active metal component and a soluble compound of a promoter component, the active metal component is Ni, and the promoter component is selected from at least one of rare earth metals; the carrier and the impregnation solution are used in an amount such that, in the prepared catalyst, the content of the carrier is 72-94wt%, the content of the active metal component is 5.9-18wt% on an oxide basis, and the content of the promoter component is 0.1-10wt%.

[0030] The catalysts for hydrogen production by steam reforming of methane in the prior art are mostly prepared by impregnation method. Due to the influence of the water absorption of the carrier, multiple impregnation or a higher concentration of the impregnation solution is often required, which leads to an increase in the grain size of the active metal component, a limitation on the activity, an increase in the preparation process, and an increase in the production cost of the catalyst. The inventors of the present application found in the research that the use of the organic adsorbent pre-adsorbed on the surface of the carrier can strengthen the adsorption of the active metal component and the promoter component onto the surface of the carrier, can realize efficient loading of the active metal component and the promoter component at a lower concentration of the impregnation solution, and can help to reduce the grain size of the active metal component and improve the catalytic activity and stability of the catalyst.

[0031] According to the present application, preferably, the carrier loaded with the organic adsorbent and the impregnation solution are used in an amount such that, in the prepared catalyst, the content of the carrier is 81-91wt%, the content of the active metal component is 8-14wt% on an oxide basis, and the content of the promoter component is 1-5wt%. With the above preferred composition, the activity and stability of the catalyst are further improved.

[0032] According to the present application, preferably, the mole ratio of the soluble compound of the active metal component to the soluble compound of the promoter component is 0.03-0.2:1, preferably 0.04-0.15:1, on an elemental basis. With the above preferred mole ratio, the combination of the active metal component and the promoter component helps to improve the activity and stability of the catalyst.

[0033] In the present application, the carrier can be selected from the conventional carriers in the art, for example, the carrier can be an oxide carrier prepared by high-temperature sintering method, for example, the carrier can be at least one of α-Al2O3, MgO-Al2O3, CaO-Al2O3, SiC and BN, preferably α-Al2O3. When α-Al2O3 is used as the carrier, the catalytic reaction activity and the anti-carbon deposition performance of the catalyst can be improved.

[0034] In the present application, preferably, the carrier is a shaped carrier, and the shaping can be a conventional shaping method in the art, for example, extrusion or compression.

[0035] In the present application, preferably, the auxiliary component is selected from at least one of La, Ce, Pr and Sm, preferably La and / or Ce. The use of the auxiliary component as described above can improve the catalytic activity and the anti-carbon deposition performance of the catalyst, and the further growth of the active metal component grains can be inhibited by the synergistic effect between the auxiliary component and the active metal component.

[0036] According to the present application, the type of the soluble compound of the active metal component is well known to those skilled in the art and can be selected from the conventional ones in the art. For example, the soluble compound of the active metal component is selected from at least one of nickel nitrate and / or nickel acetate; further preferably, nickel nitrate.

[0037] According to the present application, preferably, the concentration of the soluble compound of the active metal component in the impregnation solution is 0.5-2.5 g / mL, further preferably 0.8-1.5 g / mL; within the above concentration range, the grain size of the active metal component can be further reduced, and the catalytic activity and the anti-carbon deposition performance of the catalyst can be improved.

[0038] According to the present application, the type of the soluble compound of the auxiliary component is well known to those skilled in the art and can be selected from the conventional ones in the art. For example, the soluble compound of the auxiliary component is selected from at least one of metal nitrate, chloride and acetate; further preferably, nitrate.

[0039] In the present application, the soluble compounds of the active metal component and the auxiliary component can both carry crystal water, which is well known to those skilled in the art and will not be described here.

[0040] In the present application, the contacting of the carrier loaded with the organic adsorbent with the impregnation solution can be carried out by using the conventional operation in the art, for example, the equal volume impregnation method or the supersaturation impregnation method. Preferably, the contacting comprises: immersing the carrier loaded with the organic adsorbent in the impregnation solution for contacting. Preferably, only one impregnation is carried out in the preparation method to reach the adsorption saturation. The adsorption saturation can be judged according to the adsorption rate curve obtained in the laboratory. After a certain time of impregnation, if the adsorption amount does not change obviously, it can be judged that the adsorption saturation is reached.

[0041] According to the present application, the conditions of the contacting can be adjusted according to the actual needs, as long as the adsorption saturation described above can be achieved. Preferably, the contacting time is 10-60 min, preferably 20-35 min.

[0042] In the present application, preferably, the preparation method only comprises one contacting process. That is, the target active metal component and the auxiliary component can meet the upper amount requirement through one-step impregnation, so that the grain growth of the active metal component caused by multiple impregnations (including drying and calcination) is avoided.

[0043] In the present application, the first drying and calcination can be carried out by using the conventional operation and conditions in the art, and the present application does not have a particular limitation thereon. Preferably, the conditions of the first drying comprise: the drying temperature is 60-140℃, preferably 70-110℃; the drying time is 1-6h, preferably 2-4h.

[0044] Preferably, the conditions of the calcination comprise: the calcination temperature is 300-800℃, preferably 400-550℃; the calcination time is 1-5h, preferably 2-4h.

[0045] According to the present application, preferably, the organic adsorbent is selected from at least one of starch, glucose, α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin and maltosic; preferably, at least one of glucose, β-cyclodextrin and γ-cyclodextrin; further preferably, β-cyclodextrin and / or γ-cyclodextrin. By using the above preferred organic adsorbent, the effective adsorption of the active metal component and the auxiliary component is facilitated, and the metal upper amount in the one-step impregnation process is improved.

[0046] According to the present application, preferably, the content of the organic adsorbent is 0.05-3wt%, further preferably 0.2-1.5wt%, based on the total amount of the carrier loaded with the organic adsorbent. Under the above preferred loading amount, the suitable loading amount of the active metal and the auxiliary metal is facilitated to be regulated.

[0047] According to the present application, preferably, the carrier loaded with the organic adsorbent is obtained by the following preparation method: contacting the solution containing the organic adsorbent with the carrier, and then carrying out the pre-water removal and the second drying.

[0048] In the present application, the "first drying" and "second drying" do not refer to the order of operation, but are used to distinguish the drying mode and conditions in different steps.

[0049] The contacting can be carried out in a manner conventional in the art, for example, by contacting the solution containing the organic adsorbent with the carrier in a manner of immersion or spraying.

[0050] According to the present application, the solution further contains a solvent, preferably, the solvent is water.

[0051] Preferably, the concentration of the solution containing the organic adsorbent is 0.005-0.1 g / mL, further preferably 0.009-0.07 g / mL.

[0052] According to the present application, preferably, the pre-dewatering comprises: pre-dewatering the product obtained by the contacting in the presence of warm air until the surface is free of water; for example, the product obtained by the contacting can be placed on a vibrating screen, and then the warm air is introduced until the surface is free of water.

[0053] Preferably, the temperature of the warm air is 30-80℃, preferably 35-60℃.

[0054] According to the present application, preferably, the second drying temperature is not more than 100℃. Too high second drying temperature can cause the structure of the organic adsorbent to be destroyed, thereby affecting the adsorption effect of the active metal component and the adjuvant component.

[0055] In the present application, there is no specific requirement for the time of the second drying, as long as the thorough drying of the product obtained by the contacting is achieved. It can be understood that when the mass of the product obtained by the contacting no longer changes obviously, it can be judged that the product obtained by the contacting is thoroughly dried. For example, the time of the second drying can be 2-20 h.

[0056] According to the present application, preferably, the mode of the second drying is selected from at least one of freeze drying, low-temperature vacuum drying and low-temperature hot air drying, preferably freeze drying.

[0057] Preferably, the conditions of the freeze drying comprise: the temperature is -30℃ to -5℃, preferably -25℃ to -15℃; the drying time is 1-10 h.

[0058] Preferably, the conditions of the low-temperature vacuum drying comprise: the vacuum degree is -0.09 MPa to -0.05 MPa, preferably -0.09 MPa to -0.07 MPa; the temperature is 30-70℃, preferably 40-60℃; the drying time is 2-10 h.

[0059] Preferably, the low-temperature hot-air drying conditions include: a hot-air flow rate of 0.1-0.5 m / s, preferably 0.2-0.4 m / s; a temperature of 40-80℃, preferably 50-70℃; and a drying time of 2-10 h.

[0060] The above-mentioned preferred second drying method is beneficial to the structural stability of the organic adsorbent, and further improves the metal loading, the catalytic activity and the carbon deposition resistance of the catalyst.

[0061] The third aspect of the present application provides a methane steam reforming catalyst prepared by the above-mentioned preparation method.

[0062] The fourth aspect of the present application provides a method for preparing hydrogen by methane steam reforming, which comprises: contacting methane and water with a catalyst under the conditions for preparing hydrogen by methane steam reforming, characterized in that the catalyst is the methane steam reforming catalyst provided in the first aspect and the third aspect.

[0063] The methane steam reforming catalyst provided by the present application is used to prepare hydrogen by methane steam reforming, and a higher methane conversion rate can be obtained at a lower steam-to-carbon ratio.

[0064] The method for contacting methane and water with the catalyst is not particularly limited and can be a conventional selection in the art, and preferably, the contacting is performed in a fixed bed reactor.

[0065] Preferably, the conditions for preparing hydrogen by methane steam reforming include: a volume ratio of water to methane of (1.2-5) : 1, preferably (2.5-3.5) : 1; a reaction temperature of 600-900℃, preferably 650-850℃; a pressure of 0-4 MPa, preferably 1.5-3.5 MPa; a methane carbon space velocity of 400-5000 h -1 , preferably 600-4000 h -1 In the present application, the pressure is a gauge pressure, and the methane carbon space velocity is a volume space velocity.

[0066] According to the present application, preferably, the method further comprises: reducing and activating the catalyst under a hydrogen-containing atmosphere before the reaction.

[0067] Preferably, the reducing and activating conditions include: a reducing temperature of 300-800℃, preferably 400-600℃; a reducing time of 0.5-10 hours, preferably 1-5 hours, and further preferably 2-4 hours; and a reducing pressure of 0-2 MPa, preferably 0-1 MPa, and more preferably 0-0.5 MPa.

[0068] According to the present application, preferably, the hydrogen-containing atmosphere is hydrogen or a mixture of hydrogen and inert gas; for example, the mixture can be a mixture of hydrogen, nitrogen and / or argon. Preferably, in the mixture, the volume content of hydrogen is 10-80%, further preferably 20-60%.

[0069] The present application will be described in detail below by way of examples.

[0070] In the following examples, each of the reaction raw materials is commercially available, unless otherwise specified.

[0071] In the following examples, the content of each component in the catalyst is measured by fluorescence analysis.

[0072] The average grain size of the active metal component is measured by XRD method and calculated according to Scherrer formula.

[0073] The tail gas composition is calculated by online sampling and analysis using gas chromatography. The conversion rate of methane (X CH4 ) is calculated by the following formula:

[0074]

[0075] wherein C CH4 is the volume concentration of methane, and C N2 is the volume concentration of nitrogen.

[0076] Example 1

[0077] (1) Preparation of catalyst

[0078] 100 g of high-temperature a-Al2O3 carrier after molding was weighed for standby, and the water absorption rate of the carrier was 0.21%. 0.8 g of β-cyclodextrin was weighed into deionized water, and the volume was made up to 21 mL, and the solution was fully stirred and dissolved; then the solution was sprayed onto the molded high-temperature a-Al2O3 carrier and mixed uniformly. After that, it was placed on a vibrating screen and dried with warm air at 40°C until the surface was free of water; then it was subjected to a second drying by freeze-drying, fully dried at -20°C for 10 h, to obtain a carrier loaded with organic adsorbent. Based on the total amount of the carrier loaded with organic adsorbent, the content of the organic adsorbent was 0.79 wt%.

[0079] Take 21 g Ni(NO3)2-6H2O and 3.6 g La(NO3)2-9H2O and dissolve them in 15 mL deionized water, stirring to dissolve at room temperature. Take 10 g of the above-mentioned support loaded with organic adsorbent and immerse it in the prepared impregnation solution, stand for 30 minutes, then take out the adsorbent-saturated support from the impregnation solution, drain the water, and place it in an oven to dry at 80°C for 3 hours; place the dried sample in a muffle furnace and calcine it at 500°C for 2 hours to obtain the desired catalyst for hydrogen production by steam reforming of methane. Fluorescence analysis shows that the content of NiO in the catalyst is 12.6 wt%, the content of La2O3 is 2.3 wt%, and the rest is the support. In the catalyst, the molar ratio of the promoter component to the active metal component is about 0.084:1 on an elemental basis.

[0080] The XRD spectrum of the catalyst obtained in Example 1 is shown in Figure 1 From the spectrum, the grain size of NiO is calculated to be 5.6 nm according to the half-peak width of the diffraction of NiO in the spectrum.

[0081] (2) Activity evaluation

[0082] Take 0.2 g of the catalyst obtained in Example 1 and load it into a fixed bed reactor, reduce it at 550°C for 3 hours under a pure hydrogen atmosphere to perform reduction activation. After reduction, heat it to 700°C under a hydrogen atmosphere, switch the feed gas to perform reaction, the volume ratio of water to methane in the feed gas is 2:1, the methane carbon space velocity is 4000 h -1 , and the reaction pressure is atmospheric pressure. Online sampling and analysis of the tail gas composition by gas chromatography shows that the methane conversion rate is 89.7%.

[0083] The long-term reaction stability evaluation results of the obtained catalyst under simulated industrial application reaction conditions are shown in Figure 2 , where the inlet temperature is 600°C, the outlet temperature is 810°C, the volume ratio of water to methane is 2.8:1, the methane carbon space velocity is 1500 h -1 , and the reaction pressure is 2.5 MPa. As can be seen from Figure 2 , the reaction performance of the catalyst is very stable.

[0084] Example 2

[0085] (1) Catalyst preparation

[0086] Prepare the catalyst according to the same method as in Example 1, except that the organic adsorbent is γ-cyclodextrin, to obtain the desired catalyst for hydrogen production by steam reforming of methane. Fluorescence analysis shows that the content of NiO in the catalyst is 11.3 wt%, the content of La2O3 is 2 wt%, and the rest is the support. In the catalyst, the molar ratio of the promoter component to the active metal component is about 0.081:1 on an elemental basis.

[0087] XRD analysis results show that the grain size of NiO in the catalyst is 7.6 nm.

[0088] (2) Activity evaluation

[0089] The catalyst was activated under the same conditions as in Example 1 and subjected to the hydrogen production reaction by steam reforming of methane. The composition of the tail gas was analyzed on-line by gas chromatography, and the conversion of methane was calculated to be 86.5%.

[0090] Example 3

[0091] (1) Preparation of catalyst

[0092] The catalyst was prepared in the same manner as in Example 1, except that the second drying of the organic adsorbent was performed at 50°C for 3 h under vacuum at a vacuum degree of -0.09 MPa. The desired catalyst for hydrogen production by steam reforming of methane was obtained. Fluorescence analysis results show that the content of NiO in the catalyst is 11.9 wt%, the content of La2O3 is 2.1 wt%, and the remainder is the carrier. In the catalyst, the molar ratio of the promoter component to the active metal component is about 0.081: 1 on an elemental basis.

[0093] XRD analysis results show that the grain size of NiO in the catalyst is 7.1 nm.

[0094] (2) Activity evaluation

[0095] The catalyst was activated under the same conditions as in Example 1 and subjected to the hydrogen production reaction by steam reforming of methane. The composition of the tail gas was analyzed on-line by gas chromatography, and the conversion of methane was calculated to be 87.9%.

[0096] Example 4

[0097] (1) Preparation of catalyst

[0098] The catalyst was prepared in the same manner as in Example 1, except that the amount of β-cyclodextrin was weighed to be 1.2 g, and the content of the organic adsorbent was 1.2 wt% based on the total amount of the carrier of the loaded organic adsorbent.

[0099] The desired catalyst for hydrogen production by steam reforming of methane was obtained. Fluorescence analysis results show that the content of NiO in the catalyst is 13.5 wt%, the content of La2O3 is 2.7 wt%, and the remainder is the carrier. In the catalyst, the molar ratio of the promoter component to the active metal component is about 0.092: 1 on an elemental basis. XRD analysis results show that the grain size of NiO in the catalyst is 6.9 nm.

[0100] (2) Activity evaluation

[0101] The catalyst was activated and subjected to the steam reforming of methane under the same conditions as in Example 1. The composition of the tail gas was analyzed on-line by gas chromatography, and the conversion of methane was calculated to be 87.6%.

[0102] Example 5

[0103] (1) Preparation of the catalyst

[0104] The catalyst was prepared in the same manner as in Example 1, except that 0.17 g of β-cyclodextrin was weighed out, and the content of the organic adsorbent was 0.17 wt% based on the total amount of the support on which the organic adsorbent was loaded.

[0105] The desired catalyst for the steam reforming of methane was obtained. Fluorescence analysis showed that the concentration of NiO in the catalyst was 7.4 wt%, the content of La2O3 was 1.3 wt%, and the remainder was the support. The molar ratio of the promoter component to the active metal component in the catalyst was about 0.081:1 on an elemental basis. XRD analysis showed that the grain size of NiO in the catalyst was 4.6 nm.

[0106] (2) Activity evaluation

[0107] The catalyst was activated and subjected to the steam reforming of methane under the same conditions as in Example 1. The composition of the tail gas was analyzed on-line by gas chromatography, and the conversion of methane was calculated to be 78.5%.

[0108] Example 6

[0109] (1) Preparation of the catalyst

[0110] The catalyst was prepared in the same manner as in Example 1, except that 27 g of Ni(NO3)2-6H2O and 4.62 g of La(NO3)2-9H2O were dissolved in 15 mL of deionized water, and the desired catalyst for the steam reforming of methane was obtained. Fluorescence analysis showed that the concentration of NiO in the catalyst was 14.7 wt%, the content of La2O3 was 2.7 wt%, and the remainder was the support. The molar ratio of the promoter component to the active metal component in the catalyst was about 0.084:1 on an elemental basis.

[0111] XRD analysis showed that the grain size of NiO in the catalyst was 7.4 nm.

[0112] As can be seen from the comparison between Example 1 and Example 6, when the concentration of the soluble compound of the active metal component in the impregnation solution is too high, the grain size of NiO loaded on the support increases.

[0113] (2) Activity evaluation

[0114] The catalyst was activated and subjected to the steam reforming of methane under the same conditions as in Example 1. The composition of the tail gas was analyzed on-line by gas chromatography, and the conversion of methane was calculated to be 88.5%.

[0115] Example 7

[0116] (1) Preparation of the catalyst

[0117] The catalyst was prepared in the same manner as in Example 1, except that 21 g of Ni(NO3)2-6H2O and 1.2 g of La(NO3)2-9H2O were weighed out and dissolved in 15 mL of deionized water to obtain the desired catalyst for the steam reforming of methane. Fluorescence analysis showed that the concentration of NiO in the catalyst was 12.2 wt%, the content of La2O3 was 0.98 wt%, and the remainder was the carrier. In the catalyst, the molar ratio of the promoter component to the active metal component was about 0.03:1 on an elemental basis.

[0118] XRD analysis showed that the grain size of NiO in the catalyst was 5.3 nm.

[0119] (2) Activity evaluation

[0120] The catalyst was activated and subjected to the steam reforming of methane under the same conditions as in Example 1. The composition of the tail gas was analyzed on-line by gas chromatography, and the conversion of methane was calculated to be 86.5%.

[0121] Example 8

[0122] (1) Preparation of the catalyst

[0123] The catalyst was prepared in the same manner as in Example 1, except that the second drying method for the pre-adsorbed organic adsorbent was ordinary hot air drying at 120°C for 3 h. Fluorescence analysis showed that the content of NiO in the catalyst was 9.2 wt%, the content of La2O3 was 1.7 wt%, and the remainder was the carrier. In the catalyst, the molar ratio of the promoter component to the active metal component was about 0.085:1 on an elemental basis.

[0124] The loadings of both the active component and the promoter component were greatly reduced, indicating that high-temperature hot air drying affected the structure of the organic adsorbent, making it less capable of selectively adsorbing cations. XRD analysis showed that the grain size of NiO in the catalyst was 6.6 nm.

[0125] (2) Activity evaluation

[0126] The catalyst was activated and subjected to the steam reforming of methane under the same conditions as in Example 1. The composition of the tail gas was analyzed on-line by gas chromatography, and the conversion of methane was calculated to be 75.6%.

[0127] Example 9

[0128] (1) Preparation of catalyst

[0129] The catalyst was prepared in the same manner as in Example 1 except that the support was a high-temperature calcined MgO-Al2O3 composite oxide having a water absorption of 0.22%, to obtain a desired catalyst for hydrogen production by steam reforming of methane. Fluorescent analysis showed that the catalyst contained 13.1 wt% of NiO, 2.5 wt% of La2O3, and the remainder was the support. In the catalyst, the molar ratio of the promoter component to the active metal component was about 0.087:1 on an elemental basis.

[0130] XRD analysis showed that the grain size of NiO in the catalyst was 6.4 nm.

[0131] (2) Activity evaluation

[0132] The catalyst was activated and subjected to the hydrogen production reaction by steam reforming of methane under the same conditions as in Example 1. The composition of the tail gas was analyzed on-line by gas chromatography, and the conversion of methane was calculated to be 86.1%.

[0133] Example 10

[0134] (1) Preparation of catalyst

[0135] The catalyst was prepared in the same manner as in Example 1 except that the organic adsorbent was starch, to obtain a desired catalyst for hydrogen production by steam reforming of methane. Fluorescent analysis showed that the catalyst contained 10.9 wt% of NiO, 1.8 wt% of La2O3, and the remainder was the support. In the catalyst, the molar ratio of the promoter component to the active metal component was about 0.076:1 on an elemental basis.

[0136] XRD analysis showed that the grain size of NiO in the catalyst was 5.2 nm.

[0137] (2) Activity evaluation

[0138] The catalyst was activated and subjected to the hydrogen production reaction by steam reforming of methane under the same conditions as in Example 1. The composition of the tail gas was analyzed on-line by gas chromatography, and the conversion of methane was calculated to be 84.3%.

[0139] Comparative Example 1

[0140] (1) Preparation of catalyst

[0141] The catalyst was prepared in the same way as in Example 1, except that no organic adsorbent was adsorbed on the surface of the carrier in advance. In this case, the adsorption capacity of the carrier was poor, and the active metal content could not reach the required amount after one impregnation. Fluorescence analysis showed that the content of NiO was 6.7% and the content of La2O3 was 1.2% by weight after one impregnation, and the rest was the carrier. After two impregnations, the content of NiO in the catalyst was 11.5% by weight, the content of La2O3 was 2.2% by weight, and the rest was the carrier. The XRD spectrum of the obtained catalyst is shown in Figure 1 From the XRD spectrum, the grain size of NiO was calculated to be 13.7 nm according to the half-peak width of the diffraction of NiO in the spectrum. Figure 1 It can also be seen from the comparison of the XRD spectra of

[0142] From the comparison of Example 1 and Comparative Example 1, it can be seen that the carrier without loading of the organic adsorbent needs to be impregnated twice or three times to reach the required metal content. Due to multiple impregnations, each impregnation needs to be dried, calcined and other procedures, which also leads to an increase in the grain size of NiO on the carrier, complicated preparation process and increased production cost of the catalyst.

[0143] (2) Activity evaluation

[0144] The catalyst was activated under the same conditions as in Example 1 and subjected to the reaction of steam reforming of methane to produce hydrogen. The composition of the tail gas was analyzed online by gas chromatography, and the conversion rate of methane was calculated to be 72.2%.

[0145] At the same time, the catalyst obtained in Comparative Example 1 was subjected to carbon deposition analysis after 50 hours of reaction, and the catalyst obtained in Example 1 was subjected to carbon deposition analysis after 2000 hours of reaction. It was found that the carbon deposition amount of the catalyst obtained in Comparative Example 1 after 50 hours of reaction was 1.7% by weight, and the carbon deposition amount of the catalyst obtained in Example 1 after 2000 hours of reaction was 0.06% by weight. This shows that the catalyst prepared by the method of the present application has excellent anti-coking performance.

[0146] Comparative Example 2

[0147] (1) Preparation of catalyst

[0148] The catalyst was prepared in the same way as in Example 1, except that no additive was added when preparing the metal impregnation solution, and the desired catalyst for steam reforming of methane to produce hydrogen was obtained. Fluorescence analysis showed that the concentration of NiO in the catalyst was 13.5% by weight, and the rest was the carrier. The grain size of NiO was calculated to be 6.2 nm.

[0149] (2) Activity evaluation

[0150] The 0.2 g of the above catalyst was packed in a fixed bed reactor, reduced and activated at 550 ℃ for 3 hours under normal pressure in a pure hydrogen atmosphere. After the reduction was completed, the temperature was raised to 700 ℃ under a hydrogen atmosphere, the feed gas was switched to perform the reaction, the volume ratio of water and methane in the feed gas was 2:1, the methane carbon space velocity was 4000 h-1, the reaction pressure was normal pressure. The tail gas composition was analyzed on-line by gas chromatography, and the conversion rate of methane was calculated to be 84.8%. -1 , the reaction pressure was normal pressure. The tail gas composition was analyzed on-line by gas chromatography, and the conversion rate of methane was calculated to be 84.8%.

[0151] From the above results, it can be seen that the catalyst prepared by the preparation method provided by the present application and the catalyst prepared by the preparation method have better reaction activity and stability and anti-coking performance, and can be continuously and efficiently and stably operated for more than 2000 hours without deactivation.

[0152] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A catalyst for steam reforming of methane, characterized by, The catalyst comprises a carrier, and an active metal component and an auxiliary component supported on the carrier; wherein the active metal component is Ni, and the auxiliary component is selected from at least one of rare earth metals; wherein the average grain size of the active metal component is 3-12 nm, the content of the carrier is 72-94 wt% based on the total amount of the catalyst, the content of the active metal component is 5.9-18 wt% in terms of oxides, and the content of the auxiliary component is 0.1-10 wt%; The preparation method of the catalyst comprises the following steps: contacting a carrier loaded with an organic adsorbent with an impregnation solution, and then performing first drying and calcination; The organic adsorbent is selected from at least one of starch, glucose, α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin and maltodextrin; The carrier loaded with the organic adsorbent is obtained by the following method: contacting a solution containing the organic adsorbent with the carrier to obtain a contact product, and then performing pre-water removal and second drying; The pre-water removal comprises: pre-removing water from the contact product in the presence of warm air until no visible water is present on the surface; the temperature of the warm air is 30-80 ℃; and the second drying temperature is not higher than 100 ℃.

2. The catalyst of claim 1, wherein, The average grain size of the active metal component is 4-9 nm.

3. The catalyst of claim 1, wherein, The content of the carrier is 81-91 wt% based on the total amount of the catalyst, the content of the active metal component is 8-14 wt% in terms of oxides, and the content of the auxiliary component is 1-5 wt%.

4. The catalyst of claim 1, wherein, The temperature of the warm air is 35-60 ℃.

5. The catalyst of claim 1, wherein, The carrier is at least one of α-Al2O3, MgO-Al2O3, CaO-Al2O3, SiC and BN.

6. The catalyst of claim 5, wherein, The carrier is α-Al2O3.

7. The catalyst of claim 1, wherein, The auxiliary component is selected from at least one of La, Ce, Pr and Sm.

8. The catalyst of claim 7, wherein, The auxiliary component is La and / or Ce.

9. The catalyst of claim 1, wherein, The molar ratio of the auxiliary component to the active metal component is 0.03-0.2:1 in terms of elements.

10. The catalyst of claim 9, wherein, The molar ratio of the auxiliary component to the active metal component is 0.04-0.15:1 in terms of elements.

11. A method of making a methane steam reforming catalyst, the method comprising: The preparation method of the catalyst comprises the following steps: contacting a carrier loaded with an organic adsorbent with an impregnation solution, and then performing first drying and calcination; The impregnation solution contains soluble compounds of an active metal component and soluble compounds of an auxiliary component; the active metal component is Ni, and the auxiliary component is selected from at least one of rare earth metals; and the carrier loaded with the organic adsorbent and the impregnation solution are used in an amount such that, in the prepared catalyst, the content of the carrier is 72-94 wt%, the content of the active metal component is 5.9-18 wt% in terms of oxides, and the content of the auxiliary component is 0.1-10 wt%; The organic adsorbent is selected from at least one of starch, glucose, α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin and maltodextrin; The carrier loaded with the organic adsorbent is obtained by the following method: contacting a solution containing the organic adsorbent with the carrier to obtain a contact product, and then performing pre-water removal and second drying; The pre-removing water includes: pre-removing water of the contact product in the presence of warm air, to the surface without water; the temperature of the warm air is 30-80℃; the second drying temperature is not more than 100℃.

12. The production method according to claim 11, wherein The load organic adsorbent carrier, the soluble compound of active metal component and the soluble compound of auxiliary component are used in the amount that makes, with the total amount of the prepared catalyst as the basis, the content of the carrier is 81-91wt%, the content of the active metal component is 8-14wt% in oxide, the content of the auxiliary component is 1-5wt%.

13. The method of making according to claim 11, wherein, The temperature of the warm air is 35-60℃.

14. The method of making according to claim 11, wherein, The amount of the soluble compound of the auxiliary component and the soluble compound of the active metal component is calculated in elements, so that in the prepared catalyst, the molar ratio of the auxiliary component and the active metal component is 0.03-0.2:

1.

15. The method of manufacturing according to claim 14, wherein, The amount of the soluble compound of the auxiliary component and the soluble compound of the active metal component is calculated in elements, so that in the prepared catalyst, the molar ratio of the auxiliary component and the active metal component is 0.04-0.15:

1.

16. The method of making according to claim 11, wherein, The carrier is at least one of α-Al2O3, MgO-Al2O3, CaO-Al2O3, SiC and BN.

17. The method of making according to claim 16, wherein, The carrier is α-Al2O3.

18. The method of making according to claim 11, wherein, The auxiliary component is selected from at least one of La, Ce, Pr and Sm.

19. The method of making according to claim 18, wherein, The auxiliary component is La and / or Ce.

20. The method of manufacturing according to claim 11, wherein, The concentration of the soluble compound of the active metal component in the impregnation solution is 0.5-2.5g / mL.

21. The method of making according to claim 20, wherein, The concentration of the soluble compound of the active metal component in the impregnation solution is 0.8-1.5g / mL.

22. The method of making according to claim 11, wherein, The time of contacting the load organic adsorbent carrier with the impregnation solution is 10-60min.

23. The method of making according to claim 22, wherein, The time of contacting the load organic adsorbent carrier with the impregnation solution is 20-35min.

24. The method of manufacturing according to claim 11, wherein, The conditions of the first drying include: the drying temperature is 60-140℃; the drying time is 1-6h.

25. The method of manufacturing according to claim 24, wherein, The conditions of the first drying include: the drying temperature is 70-110℃; the drying time is 2-4h.

26. The method of manufacturing according to claim 11, wherein, The conditions of the calcination include: the calcination temperature is 300-800℃; the calcination time is 1-5h.

27. The method of making according to claim 26, wherein, The conditions of the calcination include: the calcination temperature is 400-550℃; the calcination time is 2-4h.

28. The method of manufacturing according to claim 11, wherein, The organic adsorbent is selected from at least one of glucose, β-cyclodextrin and γ-cyclodextrin.

29. The method of making according to claim 28, wherein, The organic adsorbent is β-cyclodextrin and / or γ-cyclodextrin.

30. The method of manufacturing according to claim 11, wherein, The content of the organic adsorbent is 0.05-3wt% based on the total amount of the load organic adsorbent carrier.

31. The method of manufacturing according to claim 30, wherein, The content of the organic adsorbent is 0.2-1.5wt% based on the total amount of the load organic adsorbent carrier.

32. The method of manufacturing according to claim 11, wherein, The concentration of the solution containing the organic adsorbent is 0.005-0.1g / mL.

33. The method of manufacturing according to claim 32, wherein, The concentration of the solution containing the organic adsorbent is 0.009-0.07g / mL.

34. The method of manufacturing according to claim 11, wherein, The second drying mode is selected from at least one of freeze drying, low-temperature vacuum drying and low-temperature hot air drying.

35. The method of manufacturing according to claim 34, wherein, The second drying mode is freeze drying.

36. The method of manufacturing according to claim 34 or 35, wherein, The freeze-drying conditions include a temperature of -30 to -5℃ and a time of 1-20 hours.

37. The method of manufacturing according to claim 34, wherein, The low-temperature vacuum drying conditions include a vacuum degree of -0.09 to -0.05 MPa, a temperature of 30-70℃, and a drying time of 2-10 hours.

38. The method of manufacturing according to claim 34, wherein, The low-temperature hot air drying conditions include a temperature of 40-80℃, a hot air flow rate of 0.1-0.5 m / s, and a drying time of 2-10 hours.

39. The methane steam reforming catalyst prepared by the preparation method of any one of claims 11-38.

40. A method of steam reforming of methane to produce hydrogen, the method comprising: Under the conditions of hydrogen production by methane steam reforming, methane and water are contacted with a catalyst, characterized in that the catalyst is the methane steam reforming catalyst of any one of claims 1-10 and 39.

41. The method of claim 40, wherein, The contacting is performed in a fixed bed reactor.

42. The method of claim 40, wherein, The conditions for hydrogen production by steam reforming of methane include a volume ratio of water to methane of (1.2-5):1, a reaction temperature of 600-900°C, a pressure of 0-4 MPa, and a methane carbon space velocity of 400-5000 h -1 .

43. The method of claim 42, wherein, The conditions for hydrogen production by steam reforming of methane include a volume ratio of water to methane of (2.5-3.5): 1, a reaction temperature of 650-850°C, a pressure of 1.5-3.5 MPa, and a methane carbon space velocity of 600-4000 h -1 .

44. The method of claim 40, wherein, The method further comprises, before the reaction, reduction activation of the catalyst under a hydrogen-containing atmosphere.

45. The method of claim 44, wherein, The reduction activation conditions include a reduction temperature of 300-800℃, a reduction time of 0.5-10 hours, and a reduction pressure of 0-2 MPa.

46. The method of claim 45, wherein, The reduction activation conditions include a reduction temperature of 400-600℃, a reduction time of 1-5 hours, and a reduction pressure of 0-1 MPa.

47. The method of claim 46, wherein, The reduction activation conditions include a reduction time of 2-4 hours and a reduction pressure of 0-0.5 MPa.

48. The method of claim 44, wherein, The hydrogen-containing atmosphere is hydrogen or a mixture of hydrogen and an inert gas.

49. The method of claim 48, wherein, The volume content of hydrogen in the mixture is 10-80%.

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