Platinum-based catalyst supported on NANO rod-shaped alumina and method for aqueous phase reforming of methanol

Abstract

The present invention relates to a platinum-based catalyst supported on nano rod-shaped alumina and a method for aqueous phase reforming of methanol, and also relates to a preparation method for said catalyst. The catalyst of the present invention comprises a carrier and platinum particles supported on the carrier, the carrier being nano rod-shaped alumina. The catalyst of the present invention has high catalytic activity, high selectivity, and strong catalytic stability. The preparation method for said catalyst of the present invention has simple steps, and the obtained catalyst has small platinum particle size and uniform loading. The method for aqueous phase reforming of methanol of the present invention has a simple and efficient process.

Description

Nanorod-shaped alumina-supported platinum-based catalyst and methanol aqueous phase reforming method

[0001] This application claims priority to the Chinese invention patent application with application number 202410354259.X, application date March 26, 2024, and invention name “Nanorod-shaped alumina-loaded platinum-based catalyst and methanol aqueous phase reforming method”, which is hereby incorporated by reference into this document. Technical Field

[0002] The present invention belongs to the technical field of heterogeneous catalysts and methanol aqueous phase reforming, and specifically relates to a nanorod-shaped alumina-supported platinum-based catalyst and a methanol aqueous phase reforming method. Background Art

[0003] Hydrogen energy is a clean, efficient, and energy-dense renewable energy source. In addition to directly utilizing the heat energy released by combustion, converting the heat energy released by hydrogen into electrical energy through fuel cells is also an important way to utilize hydrogen. It is also considered to be an important power system for future automobiles and other portable devices.

[0004] However, the safe storage and release of hydrogen has always been a bottleneck restricting the development of hydrogen energy. Current hydrogen-powered vehicles typically transport hydrogen via onboard hydrogen cylinders. For example, Toyota's commercial hydrogen fuel cell vehicles use two cylinders with a capacity of approximately 120L and a pressure of up to 70MPa to carry hydrogen. This method of hydrogen transportation poses significant safety risks.

[0005] Methanol has attracted widespread attention due to its high hydrogen storage density, ease of storage and transportation, and safety and efficiency. Current methods for releasing hydrogen stored in methanol include methanol steam reforming. However, this process requires a methanol and water vaporization unit, resulting in high reaction temperatures and complex equipment. In comparison, methanol aqueous reforming (AWR) does not require a vaporization unit, has a relatively low reaction temperature, and uses a simpler reactor. Developing efficient AWR catalysts is key to promoting hydrogen release from this process.

[0006] The most widely studied methanol aqueous phase reforming catalyst material can be roughly divided into two classes at present.One class is homogeneous catalyst, and this type of catalyst is usually composed of the metal complex of liquid phase, and it has that catalytic mechanism is simple, catalytic efficiency is high, and the advantage of catalytic selectivity is high, but its shortcoming is to be difficult for recycling, easily causes the loss of catalyst (referring to non-patent literature 1).Another type of catalyst is heterogeneous catalyst, and this type of catalyst is usually composed of oxide or carbide carrier loaded active metal site.The catalytic mechanism of heterogeneous catalyst is complicated, but this type of catalyst has good separation characteristics with reactant, and this makes heterogeneous catalyst receive great attention in methanol aqueous phase reforming.

[0007] For example, Non-Patent Document 2 discloses a series of Pt / α-MoC catalysts and studies their catalytic performance when used for aqueous phase reforming of methanol.

[0008] Pt / Al2O3 catalyst is the earliest heterogeneous catalyst used for methanol aqueous phase reforming. The preparation method of this catalyst is simple and the preparation process is relatively mature.

[0009] For example, non-patent document 3 discloses a Pt / Al2O3 catalyst and studies its catalytic performance when used for aqueous phase reforming of methanol.

[0010] References:

[0011] Non-patent literature 1: Nature, 2013, 495, 85-89:;

[0012] Non-patent literature 2: Nature, 2017, 544, 80-83;

[0013] Non-patent document 3: Nature, 2002, 418, 964-967. Summary of the Invention

[0014] Problems to be solved by the invention

[0015] Currently known Pt / Al2O3 catalysts have the problems of low catalytic activity and low hydrogen release rate.

[0016] The object of the present invention is to provide an alumina-supported platinum-based catalyst with high catalytic activity, high catalytic selectivity and good cyclic stability.

[0017] Solutions for solving problems

[0018] In response to the above problems, the inventors conducted in-depth research and found that by using nanorod-shaped alumina as a carrier, the obtained nanorod-shaped alumina-loaded platinum-based catalyst has high catalytic activity, high hydrogen selectivity, and good cycle stability when used for methanol aqueous phase reforming, thereby completing the present invention.

[0019] Specifically, the present invention solves the problems of the present invention through the following solutions.

[0020] [1] A catalyst comprising a support and platinum particles supported on the support, wherein the support is nanorod-shaped aluminum oxide.

[0021] [2] The catalyst according to [1], wherein the diameter of the nanorod-shaped aluminum oxide is 1 to 30 nm, the length is 5 to 100 nm, and the specific surface area is 50 to 300 m 2 / g.

[0022] [3] The catalyst according to [1] or [2], wherein the diameter of the platinum particles is 1 to 10 nm; and the content of the platinum particles is 0.5 to 8% based on the mass of the catalyst.

[0023] [4] The method for preparing the catalyst according to any one of [1] to [3], comprising the following steps:

[0024] 1) calcining the nanorod-shaped alumina to obtain pretreated nanorod-shaped alumina;

[0025] 2) mixing an aqueous solution of a platinum-based precursor with the pretreated nanorod-shaped aluminum oxide, removing water to obtain a dry powder, and calcining the dry powder to obtain a calcined powder;

[0026] 3) The calcined powder is reduced in a hydrogen atmosphere.

[0027] [5] The preparation method according to [4], wherein the calcination temperature in step 1) is 400-700°C and the calcination time is 1-6 hours; the calcination temperature in step 2) is 300-700°C and the calcination time is 1-6 hours; and the reduction temperature in step 3) is 200-800°C.

[0028] [6] The preparation method according to [4] or [5], wherein the platinum-based precursor is a water-soluble platinum salt, preferably chloroplatinic acid, platinum nitrate, potassium tetrachloroplatinate, potassium hexachloroplatinate, or tetraammineplatinum nitrate, more preferably chloroplatinic acid and / or platinum nitrate.

[0029] [7] The preparation method according to [4] or [5], wherein in step 2), a mixed solution is obtained by adding an aqueous solution of a platinum-based precursor and pretreated nanorod-shaped alumina into water and mixing them, and then the mixed solution is dried to obtain the dried powder; wherein the ratio of the platinum-based precursor, pretreated nanorod-shaped alumina and water in the mixed solution is (0.024-0.072): (1-3): (50-80) in g:g:mL.

[0030] [8] A catalyst obtained by the preparation method according to any one of [4] to [7].

[0031] [9] A method for aqueous methanol reforming, comprising the following steps:

[0032] Methanol and water are reacted in the presence of the catalyst according to any one of [1] to [3] and [8] to produce hydrogen.

[0033]

[0010] The methanol aqueous phase reforming method according to [9], wherein the molar ratio of methanol to water is 1:(3-5); the reaction temperature is 150-260° C., and the reaction pressure is 1-3 MPa; based on the total volume of methanol and water, the amount of catalyst is 1-10 g / L, preferably 1-4 g / L, and more preferably 1-2 g / L.

[0034] Effects of the Invention

[0035] The present invention has the following beneficial effects:

[0036] The catalyst of the present invention has high catalytic activity, high selectivity and strong catalytic stability.

[0037] The preparation method of the catalyst of the present invention has simple steps, and the platinum particles in the obtained catalyst have small particle size and are uniformly loaded.

[0038] The methanol aqueous phase reforming method of the present invention has simple process and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] FIG1 is a transmission electron micrograph of catalyst A obtained in Example 1;

[0040] FIG2 shows the results of Test A in the evaluation of the catalytic performance of methanol aqueous phase reforming;

[0041] FIG3 shows the results of Test B in the evaluation of methanol aqueous phase reforming catalytic performance;

[0042] FIG4 shows the results of Test C in the evaluation of the catalytic performance of methanol aqueous phase reforming;

[0043] FIG5 shows the results of Test D in the evaluation of the catalytic performance of methanol aqueous phase reforming;

[0044] FIG6 shows the results of Test E in the evaluation of the catalytic performance of methanol aqueous phase reforming;

[0045] FIG7 is a schematic diagram of the test device for evaluating the catalytic performance of methanol aqueous phase reforming. DETAILED DESCRIPTION

[0046] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The word "exemplary" is used herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior or preferred over other embodiments.

[0047] In addition, numerous specific details are provided in the following detailed description to better illustrate the present invention. Those skilled in the art will appreciate that the present invention can be practiced without certain specific details. In other instances, methods, means, equipment, and steps well known to those skilled in the art are not described in detail in order to highlight the main points of the present invention.

[0048] <Terms and Definitions>

[0049] Unless otherwise stated, the units used in this specification are international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0050] In this specification, the use of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

[0051] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "embodiments," etc., mean that the specific elements (e.g., features, structures, properties, and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it should be understood that the elements may be combined in various embodiments in any suitable manner.

[0052] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints A and B.

[0053] In this specification, when "normal temperature" or "room temperature" is used, the temperature may be 20 to 30°C.

[0054] In this specification, the "hydrogen generation rate" refers to the amount of substance that can catalyze the generation of hydrogen per unit mass of catalyst per unit time.

[0055] In this specification, the "selectivity of hydrogen" refers to the ratio of the amount of substances in methanol that are converted into hydrogen to the amount of all substances consumed in methanol.

[0056] <Nanorod-shaped alumina-supported platinum-based catalyst>

[0057] One of the objects of the present invention is to provide a catalyst comprising a carrier and platinum particles supported on the carrier, wherein the carrier is nanorod-shaped aluminum oxide.

[0058] The present invention uses nanorod-shaped alumina with a good size effect as a catalyst carrier, utilizes the rich surface defect sites brought about by the good size effect of nanorod-shaped alumina to enhance the anchoring effect of alumina on platinum particles, and utilizes the rich surface hydroxyl sites brought about by the size effect to enhance the hydrophilicity and dispersibility of the catalyst, thereby giving the catalyst excellent catalytic performance (hydrogen generation rate, hydrogen selectivity).

[0059] In one embodiment, the diameter of the nanorod-shaped aluminum oxide is 1 to 30 nm, preferably 5 to 20 nm. Herein, the "diameter" described for the nanorod-shaped aluminum oxide refers to the maximum length of the cross section of the nanorod-shaped aluminum oxide.

[0060] In one embodiment, the length of the nanorod-shaped aluminum oxide is 5 to 100 nm, preferably 10 to 80 nm, more preferably 20 to 70 nm, and even more preferably 30 to 60 nm. Herein, the "length" of the nanorod-shaped aluminum oxide refers to the maximum distance between the two end points in the longitudinal direction of the nanorod-shaped aluminum oxide.

[0061] In one embodiment, the specific surface area is 50 to 300 m 2 / g, preferably 100 to 200 m 2 / g. Specific surface area can be measured by gas adsorption. The test principle is that the surface of the sample particles undergoes reversible physical adsorption of gas molecules at ultra-low temperatures, and a definite equilibrium adsorption capacity exists at a certain pressure. By measuring the equilibrium adsorption capacity of the sample at different pressures, the specific surface area of ​​the sample can be equivalently calculated using a theoretical model.

[0062] In one embodiment, the particle size of the platinum particles is 1 to 10 nm, preferably 1.2 to 5 nm, and more preferably 1.5 to 3 nm. The particle size of the platinum particles can be determined based on a TEM image of the catalyst.

[0063] The present invention also relates to the use of the catalyst of the present invention for aqueous phase reforming of methanol.

[0064] In one embodiment, when the catalyst of the present invention is used for aqueous phase reforming of methanol, the hydrogen generation rate is 5 μmol g -1 s -1 Above, preferably 7 μmol g -1 s -1 More preferably, 8 μmol g -1 s -1 More preferably, 10 μmol g -1 s -1 Above, particularly preferably 15 μmol g -1 s -1 Above, very particularly preferably 20 μmol g -1 s -1 above.

[0065] In one embodiment, when the catalyst of the present invention is used for aqueous phase reforming of methanol, the hydrogen selectivity is above 95%, preferably above 96%.

[0066] <Catalyst Preparation Method>

[0067] One of the objects of the present invention is to provide a method for preparing the catalyst of the present invention, which comprises the following steps:

[0068] 1) calcining the nanorod-shaped alumina to obtain pretreated nanorod-shaped alumina;

[0069] 2) mixing an aqueous solution of a platinum-based precursor with the pretreated nanorod-shaped aluminum oxide, removing water to obtain a dry powder, and calcining the dry powder to obtain a calcined powder;

[0070] 3) The calcined powder is reduced in a hydrogen atmosphere.

[0071] The preparation method of the present invention has the advantages of simple steps, small particle size of platinum particles in the obtained catalyst and uniform loading.

[0072] Each step in the above preparation method is described below.

[0073] Step 1)

[0074] In step 1), the nanorod-shaped aluminum oxide as a raw material is calcined to obtain pretreated nanorod-shaped aluminum oxide.

[0075] In one embodiment, the calcination temperature in step 1) is 400-700°C, preferably 500-600°C.

[0076] In one embodiment, the calcination time in step 1) is 1 to 6 hours, preferably 2 to 4 hours.

[0077] In one embodiment, the heating rate of the calcination in step 1) is 1 to 20° C. / min, preferably 3 to 10° C. / min.

[0078] In one embodiment, the calcination in step 1) is performed in an air atmosphere.

[0079] Step 2)

[0080] In step 2), the platinum-based precursor is loaded on the pretreated nanorod-shaped alumina as a catalyst support by an impregnation method.

[0081] In one embodiment, the dry powder is obtained by adding an aqueous solution of a platinum-based precursor and pretreated nanorod-shaped aluminum oxide into water, mixing the mixture, and then drying the mixture. Preferably, the mixture is stirred at 80° C. to dry it.

[0082] Preferably, the ratio of the platinum-based precursor, the pretreated nanorod-shaped aluminum oxide and water in the mixed solution is (0.024-0.072): (1-3): (50-80) in terms of mass: mass: volume (g:g:mL).

[0083] Preferably, the content of the platinum-based precursor in the aqueous solution of the platinum-based precursor is 1 to 8 wt %.

[0084] In one embodiment, the platinum-based precursor is a water-soluble platinum salt, preferably one or more selected from chloroplatinic acid, platinum nitrate, potassium tetrachloroplatinate, potassium hexachloroplatinate, and tetraammineplatinum nitrate, more preferably chloroplatinic acid and / or platinum nitrate.

[0085] In one embodiment, the calcination temperature in step 2) is 300-700°C, preferably 350-600°C, more preferably 350-500°C.

[0086] In one embodiment, the calcination in step 2) is carried out in an air atmosphere.

[0087] In one embodiment, the calcination time in step 2) is 1 to 6 hours, preferably 2 to 4 hours.

[0088] The platinum-based precursor is converted into platinum oxide by calcination.

[0089] Step 3)

[0090] In step 3, the calcined powder obtained in step 2) is reduced in a hydrogen atmosphere, so that the platinum oxide is reduced to platinum particles under the action of hydrogen.

[0091] In one embodiment, the reduction temperature in step 3) is 200-800°C, preferably 300-700°C.

[0092] In one embodiment, the reduction time in step 3) is 1 to 4 hours, preferably 1.5 to 3 hours.

[0093] In one embodiment, the reduction is carried out by continuously introducing hydrogen into a container containing the calcined powder, wherein the container is preferably a tube furnace.

[0094] Preferably, the hydrogen flow rate is 150 to 600 mL / min / g, preferably 200 to 500 mL / min / g, based on the mass of the calcined powder.

[0095] The present invention also accordingly relates to the catalyst obtainable by the process of the present invention.

[0096] <Methanol Aqueous Phase Reforming>

[0097] One of the objects of the present invention is to provide a method for aqueous methanol reforming, which comprises the following steps:

[0098] Methanol and water are reacted in the presence of the catalyst of the present invention to produce hydrogen.

[0099] The methanol aqueous phase reforming method of the present invention can be carried out in a known suitable reactor, such as a kettle reactor (autoclave), a high-pressure fixed-bed reactor, etc. The method of the present invention uses aqueous phase reforming as the basic method for releasing hydrogen, and the kettle reactor is the site for hydrogen release, making the methanol aqueous phase reforming more simple and efficient.

[0100] In one embodiment, methanol, water and a catalyst are added to a reaction vessel, and an inert gas (such as nitrogen) is introduced to exclude air until the reaction pressure is reached, and the temperature is raised to the reaction temperature to carry out the methanol aqueous phase reforming reaction.

[0101] In one embodiment, the molar ratio of methanol to water is 1:(3-5);

[0102] In one embodiment, the reaction temperature is 150 to 260°C, preferably 180 to 240°C, more preferably 185 to 245°C, and further preferably 190 to 230°C.

[0103] In one embodiment, the reaction pressure is 1 to 3 MPa, preferably 1.5 to 2.5 MPa.

[0104] In one embodiment, the reaction time is 0.1 to 10 hours, preferably 0.5 to 5 hours, more preferably 0.8 to 3 hours.

[0105] In one embodiment, the amount of the catalyst used is 1 to 10 g / L, preferably 1 to 4 g / L, and more preferably 1 to 2 g / L, based on the total volume of methanol and water.

[0106] In one embodiment, in the methanol aqueous phase reforming method of the present invention, the hydrogen generation rate is 5 μmol g -1 s -1 Above, preferably 7 μmol g -1 s -1 More preferably, 8 μmol g -1 s -1 More preferably, 10 μmol g -1 s -1 Above, particularly preferably 15 μmol g -1 s -1 Above, very particularly preferably 20 μmol g -1 s -1 above.

[0107] In one embodiment, in the methanol aqueous phase reforming method of the present invention, the hydrogen selectivity is above 95%, preferably above 96%.

[0108] Example

[0109] The above scheme is further described below with reference to non-limiting examples, so that those skilled in the art can have a more comprehensive understanding of the present invention. It should be noted that this does not limit the scope of protection of the present invention. Professionals and technicians can make several improvements and modifications without departing from the principles of the present invention. Such improvements and modifications should also be included in the scope of protection of the embodiments of the present invention.

[0110] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or those recommended by the manufacturer. All reagents or instruments used, if the manufacturer is not specified, are commercially available conventional products.

[0111] The description of the nanorod-shaped aluminum oxide used in the following examples is as follows:

[0112] Brand: Aladdin; CAS No.: 1344-28-1; Product No.: A102091; Diameter: approximately 5 nm; Length: 30 nm; Specific surface area: 150 m 2 g -1 .

[0113] Example 1:

[0114] 1) Pretreatment of nanorod-shaped alumina support

[0115] The nanorod-shaped aluminum oxide was pretreated by calcining in an air atmosphere in a muffle furnace at a calcination temperature of 550° C., a muffle furnace heating rate of 5° C. / min, and a calcination time of 4 h.

[0116] 2) Platinum particle loading

[0117] Chloroplatinic acid and pretreated nanorod-shaped alumina were added to deionized water and stirred thoroughly. The solid-to-liquid ratio (g:g:mL) of chloroplatinic acid, nanorod-shaped alumina, and deionized water was 0.048:1:50. The mixed suspension was placed in an oil bath and stirred until dry. The dried powder sample was calcined in an air atmosphere in a muffle furnace at 500°C, a heating rate of 5°C / min, and a calcination time of 4 hours.

[0118] 3) Hydrogen reduction

[0119] In a tubular furnace, 0.3 g of the powder material obtained in step 2) was reduced under a hydrogen atmosphere at a reduction temperature of 500° C., a hydrogen reduction gas flow rate of 80 mL / min, and a reduction time of 2 h to obtain catalyst A.

[0120] Examples 2-3

[0121] Except that the nanorod-shaped alumina carrier is replaced by block alumina (brand: McLean; CAS number: 1344-28-1; item number: A820850) or flake alumina (brand: Hengyi Chemical; CAS number: 14762-49-3; item number: HY-305-1), other conditions are the same as those in Example 1 to obtain Catalyst B and Catalyst C.

[0122] Examples 4-5

[0123] Except that the calcination time of the pretreatment was changed to 2 h and 3 h, other conditions were the same as those in Example 1, and catalysts D and E were obtained.

[0124] Example 6

[0125] Except that chloroplatinic acid in Example 1 was replaced by platinum nitrate, other conditions were the same as those in Example 1 to obtain Catalyst F.

[0126] Examples 7 to 17

[0127] Except that the solid-liquid ratio of chloroplatinic acid, nanorod-shaped aluminum oxide and deionized water in Example 1 was changed to 0.024:1:50, 0.032:1:50, 0.040:1:50, 0.048:1:50, 0.048:2:50, 0.072:3:50, 0.056:2:50, 0.064:2:50, 0.024:1:60, 0.032:1:70, and 0.040:1:80, other conditions were the same as those in Example 1 to obtain catalysts G to Q.

[0128] Examples 18 to 20

[0129] Except that the calcination temperature of the powder sample in step 2) was changed to 350°C, 400°C, and 450°C, and the calcination time was changed to 2 h, other conditions were the same as those in Example 1, and catalysts R to catalyst T were obtained.

[0130] Examples 21 to 24

[0131] Except that the reduction temperature in step 3) was changed to 300°C, 400°C, 600°C, and 700°C, other conditions were the same as those in Example 1, and catalysts U to X were obtained.

[0132] The preparation conditions of Examples 1 to 24 are shown in Table 1. For Examples 2 to 24, the conditions not shown in Table 1 are the same as those of Example 1.

[0133] Table 1

[0134] <Evaluation>

[0135] Transmission electron microscopy evaluation

[0136] A transmission electron microscope (TEM) photograph of the catalyst A of Example 1 was obtained using a transmission electron microscope, as shown in FIG1 .

[0137] As shown in Figure 1, the alumina support in Catalyst A exhibits a nanorod-like morphology, with the nanorods filled with pores. Platinum particles are uniformly loaded on the support, with a particle size of approximately 2 nm.

[0138] Evaluation of catalytic performance of methanol aqueous phase reforming

[0139] The hydrogen generation rate and hydrogen selectivity in the following tests were determined as follows.

[0140] Hydrogen generation rate: The gas generated after the reaction is collected using a gas bag, and the composition of the generated gas is tested by gas chromatography. The inert gas nitrogen is used as the internal standard to calculate the hydrogen generation rate R H The calculation formula is as follows, where n H is the amount of hydrogen in the generated gas, t is the time of reaction, m catalyst is the mass of the catalyst involved in the reaction,

[0141] The selectivity of hydrogen S H : refers to the ratio of the amount of substances in methanol converted into hydrogen to the total amount of methanol consumed. The calculation formula is as follows, where n H is the amount of hydrogen in the produced gas, n methanol is the consumption of methanol during the reaction,

[0142] Test A

[0143] Methanol aqueous phase reforming catalytic reaction method: As shown in Figure 7, 30 mL of a mixture of methanol and deionized water (1:3 molar ratio, where the volume ratio of methanol to water is 12.86:17.14) and 100 mg of Catalyst A were placed in a 100 mL autoclave. The reaction system was purged of air with nitrogen and pressurized to 2 MPa. The reaction was conducted at 190°C for 1.25 hours, and the hydrogen generation rate and selectivity were measured.

[0144] Aqueous methanol reforming was performed using Catalyst B, Catalyst C, and the reference catalyst in the same manner, and the hydrogen generation rate and hydrogen selectivity were measured. The results are shown in Figure 2.

[0145] The reference catalyst was prepared according to the Pt / Al2O3 method in the literature Lin, L., Zhou, W., Gao, R. et al. Low-temperature hydrogen production from water and methanol using Pt / α-MoC catalysts. Nature 544, 80-83 (2017).

[0146] As shown in Figure 2, the hydrogen generation rate of catalyst A is about 4 times that of the reference catalyst and is also significantly higher than that of catalysts B and C. The hydrogen generation rate of the reference catalyst is 4.9 μmol g -1 s -1 The hydrogen generation rate of catalyst A was 20.4 μmol g -1 s -1 , the hydrogen generation rate of catalyst B is 5.4g -1 s -1 The hydrogen generation rate of catalyst C is 6.5 μmol g -1 s -1 As for the selectivity, the selectivities of the four catalysts were 99.9%, 97.1%, 95.0% and 96.7%, respectively.

[0147] Test B

[0148] Except for setting the reaction temperature to 190°C, 210°C, and 230°C, the methanol aqueous phase reforming catalytic reaction was carried out according to the above method, and the hydrogen generation rate and hydrogen selectivity were tested respectively. The results are shown in Figure 3.

[0149] As shown in Figure 3, the hydrogen generation rate increases with the increase of reaction temperature. At 210 and 230 °C, the hydrogen generation rates reach 44.1 and 106.7 μmol g, respectively. -1 s -1 This is presumably because aqueous methanol reforming is an endothermic reaction. As the reaction temperature increases, the reaction proceeds in the endothermic direction, i.e., the forward direction, thereby increasing the hydrogen production rate. Figure 3 also shows that the catalyst's hydrogen selectivity remains above 96% at various temperatures.

[0150] Test C

[0151] Except for setting the catalyst dosage to 50 mg, 100 mg, and 150 mg, respectively, the methanol aqueous phase reforming catalytic reaction was carried out according to the above method, and the hydrogen generation rate and hydrogen selectivity were tested respectively. The results are shown in Figure 4.

[0152] Figure 4 shows that catalyst dosage affects the hydrogen generation rate during aqueous methanol reforming. The highest hydrogen generation rate is achieved at a catalyst dosage of 50 mg. However, increasing the catalyst dosage (100 and 150 mg) significantly decreases the hydrogen generation rate. This suggests that increasing the catalyst dosage may lead to excessive catalyst use, which in turn prevents the full catalytic activity per unit mass of catalyst.

[0153] Test D

[0154] Catalyst A, Catalyst U, Catalyst V, Catalyst W, and Catalyst X were used to carry out methanol aqueous phase reforming catalytic reactions according to the above method, and the hydrogen generation rate and hydrogen selectivity were tested respectively. The results are shown in FIG5 .

[0155] As shown in Figure 5, the reduction temperature during catalyst preparation also affects the catalytic activity of the catalyst. The hydrogen generation rates of catalysts U, V, A, W, and X are 8.7 μmol g -1 s -1 , 10.8 μmol g -1 s -1 , 20.4 μmol g -1 s -1 , 8.9 μmol g -1 s -1 , 5.1 μmol g -1 s -1 The hydrogen selectivities were 96.6%, 98.8%, 96.6%, 98.5% and 95.1% respectively.

[0156] Among them, Catalyst A, prepared at a reduction temperature of 500°C, had the highest hydrogen generation rate, while catalysts prepared at higher and lower reduction temperatures had relatively low hydrogen generation rates. Catalysts U, V, A, and W, prepared at reduction temperatures between 300°C and 600°C, all achieved hydrogen selectivities exceeding 96%. However, Catalyst X, prepared at a reduction temperature of 700°C, had a lower hydrogen selectivity.

[0157] Test E

[0158] Using catalyst A, methanol aqueous phase reforming catalytic reaction was carried out according to the above method. The number of cycle reactions was 3, and the hydrogen generation rate and hydrogen selectivity were tested respectively. The results are shown in Figure 6.

[0159] As shown in Figure 6, the hydrogen generation rate of the catalyst in the first three cycles was 20 μmol g -1 s -1 As shown above, the selectivity of hydrogen is above 96%, which indicates that the catalyst has excellent cycle stability when reused.

[0160] Industrial applicability

[0161] The catalyst of the invention can be widely used in aqueous phase reforming of methanol to prepare hydrogen.

Claims

1. A catalyst, characterized in that The invention comprises a carrier and platinum particles loaded on the carrier, wherein the carrier is nanorod-shaped aluminum oxide.

2. The catalyst according to claim 1, characterized in that The diameter of the nanorod-shaped aluminum oxide is 1 to 30 nm, the length is 5 to 100 nm, and the specific surface area is 50 to 300 m 2 / g.

3. The catalyst according to claim 1 or 2, characterized in that The diameter of the platinum particles is 1 to 10 nm; based on the mass of the catalyst, the content of the platinum particles is 0.5 to 8%.

4. The method for preparing a catalyst according to any one of claims 1 to 3, characterized in that: The following steps are involved: 1) calcining the nanorod-shaped alumina to obtain pretreated nanorod-shaped alumina; 2) mixing an aqueous solution of a platinum-based precursor with the pretreated nanorod-shaped aluminum oxide, removing water to obtain a dry powder, and calcining the dry powder to obtain a calcined powder; 3) The calcined powder is reduced in a hydrogen atmosphere.

5. The preparation method according to claim 4, characterized in that The calcination temperature in step 1) is 400-700° C. and the calcination time is 1-6 hours; the calcination temperature in step 2) is 300-700° C. and the calcination time is 1-6 hours; and the reduction temperature in step 3) is 200-800° C.

6. The preparation method according to claim 4 or 5, characterized in that The platinum-based precursor is a water-soluble platinum salt, preferably chloroplatinic acid, platinum nitrate, potassium tetrachloroplatinate, potassium hexachloroplatinate, tetraammineplatinum nitrate, more preferably chloroplatinic acid and / or platinum nitrate.

7. The preparation method according to claim 4 or 5, characterized in that In step 2), a mixed solution is obtained by adding an aqueous solution of a platinum-based precursor and pretreated nanorod-shaped alumina into water and mixing them, and then the mixed solution is dried to obtain the dry powder; wherein the ratio of the platinum-based precursor, pretreated nanorod-shaped alumina and water in the mixed solution is (0.024-0.072): (1-3): (50-80) in g:g:mL.

8. A catalyst obtained by the preparation method according to any one of claims 4 to 7.

9. A method for aqueous phase reforming of methanol, characterized in that: The following steps are involved: Methanol and water are reacted in the presence of the catalyst according to any one of claims 1 to 3 and 8 to produce hydrogen.

10. The methanol aqueous phase reforming method according to claim 9, characterized in that: The molar ratio of methanol to water is 1:(3-5); the reaction temperature is 150-260°C, and the reaction pressure is 1-3 MPa; based on the total volume of methanol and water, the catalyst dosage is 1-10 g / L, preferably 1-4 g / L, and more preferably 1-2 g / L.

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