A Pt-based catalyst and its preparation method and application

Abstract

The present invention discloses a Pt-based catalyst and its preparation method and application, belonging to the technical field of dehydrogenation catalysts. The preparation method of the Pt-based catalyst comprises the following steps: mixing an aqueous solution I containing magnesium ions, aluminum ions and platinum ions with an aqueous solution II containing a hydroxide-containing alkaline compound and a carbonate, and reacting to obtain a Pt-based catalyst. The preparation method of the present invention utilizes PtCl6 2‑ The strong electrostatic interaction with the magnesium-aluminum hydrotalcite layer (positively charged) and the change of Pt loading amount realize the microstructural regulation of Pt in the Pt-based catalyst. The Pt-based catalyst prepared by this method has a small Pt particle size, a highly dispersed state, and a high atomic utilization rate. When it is used for the dehydrogenation reaction of methylcyclohexane, compared with the catalyst prepared by the traditional impregnation method, under the same reaction conditions, the methylcyclohexane conversion rate is increased by 3.3 times, and it also has good stability.

Description

Technical Field

[0001] The present invention relates to the technical field of dehydrogenation catalysts, and in particular to a Pt-based catalyst and a preparation method and application thereof. Background Art

[0002] Hydrogen energy is a green, pollution-free, renewable and clean energy source and an important component of the energy system. The application of hydrogen energy mainly includes hydrogen production and storage and transportation. Among them, storage and transportation are the key factors restricting the large-scale application of hydrogen energy. Among many methods, the most common method is to use organic liquid chemical hydrogen storage technology to store and transport hydrogen energy. Organic liquid chemical hydrogen storage technology achieves hydrogen energy storage through catalytic hydrogenation / dehydrogenation reactions. The charging and discharging of hydrogen energy is relatively safe and efficient, and the conversion of hydrogen energy into liquid facilitates long-distance transportation, which has broad application prospects.

[0003] However, the dehydrogenation reaction in organic liquid chemical hydrogen storage technology is an endothermic process, and other side reactions such as cracking are prone to occur at high temperatures, resulting in reduced hydrogen purity and reduced recyclability of hydrogen storage carriers. Therefore, it is crucial to research and develop highly active and highly selective dehydrogenation catalysts to reduce side reactions caused by overheating.

[0004] Pt-based catalysts are widely used in various alkane dehydrogenation reactions because they can efficiently and selectively activate CH bonds. In order to further develop high-performance alkane dehydrogenation catalysts, it is very necessary to master the microstructure regulation strategy of the active metal Pt. As the main active site, Pt has a suitable microstructure that can not only promote the adsorption and activation of reactants, but also enhance the desorption of products, taking into account the high conversion rate, high selectivity and excellent stability of the catalytic process. Therefore, the development of a convenient Pt microstructure regulation strategy can match the optimal microstructure of Pt for different reaction substrates, thereby effectively reducing the reaction energy barrier and enabling the catalyst to exhibit higher catalytic activity and anti-carbon deposition stability. Summary of the invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a Pt-based catalyst and its preparation method and application. The preparation method of the Pt-based catalyst of the present invention makes the prepared catalyst have a small Pt particle size, a highly dispersed state, a high atomic utilization rate, and has high catalytic activity and stability when used in the dehydrogenation reaction of methylcyclohexane.

[0006] The invention provides a method for preparing a Pt-based catalyst, comprising the following steps: mixing an aqueous solution I containing magnesium ions, aluminum ions and platinum ions with an aqueous solution II containing a hydroxide-containing alkaline compound and a carbonate, and reacting to obtain a Pt-based catalyst.

[0007] Preferably, the magnesium ions are provided by one or more of magnesium nitrate hexahydrate, magnesium acetate tetrahydrate, and magnesium chloride; more preferably, the magnesium ions are provided by magnesium nitrate hexahydrate.

[0008] Preferably, the aluminum ions are provided by one or more of aluminum nitrate nonahydrate, aluminum chloride hexahydrate, and anhydrous aluminum chloride; more preferably, the aluminum ions are provided by aluminum nitrate nonahydrate.

[0009] Preferably, the platinum ions are provided by a chloroplatinate-containing compound, and the chloroplatinate-containing compound includes but is not limited to chloroplatinic acid, potassium chloroplatinate, and ammonium chloroplatinate.

[0010] Preferably, the platinum ions are provided by one or more of chloroplatinic acid, potassium chloroplatinate, and ammonium chloroplatinate; more preferably, the platinum ions are provided by chloroplatinic acid.

[0011] Preferably, the molar ratio of magnesium ions to aluminum ions is (1-5):1; more preferably (2-4):1; further preferably 2:1.

[0012] Preferably, the sum of the molar concentrations of the magnesium ions and the aluminum ions is 0.1 to 1 mol / L; more preferably 0.4 to 0.8 mol / L; further preferably 0.6 mol / L.

[0013] Preferably, the molar concentration of the platinum ions is 0.1 to 20 mmol / L; more preferably 1 to 5 mmol / L; further preferably 1.3 mmol / L.

[0014] Preferably, the molar ratio of platinum ions to magnesium ions is (1-25):1000; more preferably (4-8):1000.

[0015] Preferably, the hydroxide-containing alkaline compound in step 2) is selected from sodium hydroxide or potassium hydroxide; more preferably, the hydroxide-containing alkaline compound is sodium hydroxide.

[0016] Preferably, the carbonate is selected from sodium carbonate or potassium carbonate; more preferably, the carbonate is sodium carbonate.

[0017] Preferably, the molar ratio of the hydroxide-containing alkaline compound to the carbonate is (1-5):1; more preferably (1-3):1; further preferably 2:1.

[0018] Preferably, the sum of the molar concentrations of the hydroxide-containing alkaline compound and the carbonate is 1 to 5 mol / L; more preferably 2 to 3 mol / L; and further preferably 2.4 mol / L.

[0019] The aqueous solutions I and II of the present invention both use one or more of distilled water, deionized water, and ultrapure water as solvent; more preferably, deionized water is used as solvent.

[0020] Preferably, the volume ratio of the aqueous solution I to the aqueous solution II is (0.5-4):1, and more preferably (0.5-2):1. In some specific embodiments of the present invention, the volume ratio of the aqueous solution I to the aqueous solution II is 1:1.

[0021] Preferably, the pH value of the reaction is 7 to 14; more preferably, the pH value is 7 to 9.5.

[0022] Preferably, in the process of mixing aqueous solution I and aqueous solution II, the pH value of the system is controlled to remain unchanged, specifically, the pH value can be controlled to remain unchanged by controlling the dropping speed and stirring speed.

[0023] The present invention monitors the pH value of the system through a pH meter and controls it to remain unchanged, thereby ensuring that the carrier (magnesium-aluminum hydrotalcite layer plate) has suitable alkaline properties, thereby reducing the problem of carbon deposition and deactivation of the catalyst occurring during the dehydrogenation reaction.

[0024] Preferably, the reaction further comprises crystallization and calcination after completion.

[0025] In the present invention, solution I and solution II are mixed. Preferably, solution I and solution II are dropped into water respectively for mixing and reaction. After the reaction is completed, the system is subjected to post-treatment such as crystallization, washing, drying, and calcination.

[0026] The crystallization solvent is water, which may be one or more of distilled water, deionized water, and ultrapure water.

[0027] Preferably, the crystallization temperature is 50-100°C; more preferably, the crystallization temperature is 70-100°C.

[0028] Preferably, the crystallization time is 5 to 24 hours; more preferably, the crystallization time is 8 to 16 hours.

[0029] In the preparation method of the present invention, after the crystallization is completed, the suspension is filtered to obtain the crystals, and then the crystals are washed.

[0030] The present invention has no particular limitation on the washing method described in the above preparation method, and the washing method may be a method well known to those skilled in the art, such as centrifugation, vacuum filtration, normal pressure filtration, etc.

[0031] After washing the crystals, they are dried and calcined.

[0032] The present invention has no particular limitation on the drying method described in the above preparation method, and it can be a method well known to those skilled in the art, such as normal pressure drying, vacuum drying, freeze drying, etc.

[0033] Preferably, the drying temperature is 40-100°C; more preferably, the drying temperature is 60-100°C.

[0034] Preferably, the drying time is 4 to 24 hours; more preferably, the drying time is 6 to 12 hours.

[0035] Preferably, the calcining atmosphere is selected from one or more of vacuum, nitrogen, argon, helium and air; more preferably, the calcining atmosphere is air.

[0036] Preferably, the calcination temperature is 300-800°C; more preferably, the calcination temperature is 400-600°C.

[0037] Preferably, the calcination time is 2 to 6 hours; more preferably, the calcination time is 2 to 4 hours.

[0038] After the aqueous solution I and the aqueous solution II are mixed and reacted, the Pt-based catalyst is obtained through the above-mentioned crystallization, washing, drying and calcination treatments.

[0039] The specific composition of the above Pt-based catalyst is Pt / MgAlO. Since the components of the catalyst are complex, only the elemental composition is shown here.

[0040] The preparation method of the Pt-based catalyst of the present invention specifically comprises the following steps:

[0041] 1) a compound containing magnesium ions and aluminum ions is prepared into a mixed salt solution, and an aqueous solution containing platinum ions is added and mixed to obtain a mixed system S1;

[0042] 2) preparing a mixed alkaline solution S2 with a hydroxide-containing alkaline compound and a carbonate;

[0043] 3) The mixed alkaline solution S2 and the mixed system S1 are mixed to obtain a suspension, while keeping the pH value unchanged.

[0044] 4) The suspension is crystallized, washed, dried and calcined to obtain a Pt-based catalyst.

[0045] The preparation method of the present invention introduces a platinum source during the pre-synthesis process, using PtCl6 2- The strong electrostatic interaction between Pt and magnesium-aluminum hydrotalcite sheets (positively charged) and the change in loading amount enable the microstructure regulation of Pt in Pt-based catalysts, resulting in high Pt dispersion and electronic and geometric structures suitable for catalytic dehydrogenation of alkanes, which are then applied to the dehydrogenation reaction of methylcyclohexane.

[0046] The present invention also provides a Pt-based catalyst prepared by the above-mentioned preparation method.

[0047] Preferably, in the Pt-based catalyst, based on the mass of the catalyst as 100%, the Pt loading is ≤10wt%; more preferably, the Pt loading is 0.01wt% to 5wt%; further preferably, the Pt loading is 0.1wt% to 3wt%.

[0048] In some specific embodiments of the present invention, based on the mass of the catalyst being 100%, the loading amount of Pt is 0.5 wt%, 0.7 wt%, or 1 wt%.

[0049] The present invention adjusts the loading amount of Pt to change the activation energy of the reaction to a certain extent. In some specific embodiments of the present invention, when the loading amount of Pt is 0.5wt%, the activation energy is 44KJ·mol -1 When the Pt loading is 0.7wt%, the activation energy is 37KJ·mol -1 ; When the Pt loading is 1wt%, the activation energy is 48KJ·mol -1 This indicates that the active sites have undergone certain changes, and thus the amount of Pt loaded in the catalyst will have a certain effect on its microstructure.

[0050] The present invention also provides a methylcyclohexane dehydrogenation method, which uses the Pt-based catalyst prepared by the above preparation method as a dehydrogenation catalyst and directly contacts and reacts with reaction gas containing methylcyclohexane to obtain hydrogen and toluene.

[0051] The present invention has no particular limitation on the reactor for the methylcyclohexane dehydrogenation reaction, and it may be a fixed bed reactor.

[0052] Preferably, the concentration of methylcyclohexane in the reaction gas is 1% to 100%, and more preferably 20% to 100%. When the reaction gas is fed at a concentration of 100% methylcyclohexane, the catalyst is also stable.

[0053] Preferably, the methylcyclohexane feed volume flow rate is 1.2 to 6 mL / h.

[0054] Preferably, the reaction gas also contains carrier gas. When the concentration of methylcyclohexane is 100%, the reaction gas does not contain carrier gas.

[0055] Preferably, the carrier gas is selected from one or more of nitrogen, argon, helium and hydrogen.

[0056] Preferably, the volume flow rate of the carrier gas is 5 to 20 mL / min.

[0057] Preferably, the volume space velocity of the methylcyclohexane dehydrogenation reaction is 2000-10000h -1.

[0058] Preferably, the temperature of the methylcyclohexane dehydrogenation reaction is 200-400° C., more preferably 250-400° C. In some specific embodiments of the present invention, the temperature of the methylcyclohexane dehydrogenation reaction is 300° C., which is conducive to reducing side reactions caused by overheating.

[0059] Preferably, the reaction pressure is normal pressure.

[0060] Compared with the prior art, the preparation method of the Pt-based catalyst provided by the present invention comprises the following steps: mixing an aqueous solution I containing magnesium ions, aluminum ions and platinum ions with an aqueous solution II containing a hydroxide-containing alkaline compound and a carbonate, and reacting to obtain a Pt-based catalyst. 2- The strong electrostatic interaction with the magnesium-aluminum hydrotalcite layer (positively charged) and the change of Pt loading amount realize the microstructural regulation of Pt in the Pt-based catalyst. The Pt-based catalyst prepared by this method has a small Pt particle size, a highly dispersed state, and a high atomic utilization rate. When it is used for the dehydrogenation reaction of methylcyclohexane, compared with the catalyst prepared by the traditional impregnation method, under the same reaction conditions, the methylcyclohexane conversion rate is increased by 3.3 times, and it also has good stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 is a graph showing the conversion rate of methylcyclohexane dehydrogenation catalyzed by the catalyst;

[0062] Figure 2 This is the stability performance diagram of methylcyclohexane dehydrogenation catalyzed by catalyst 2#;

[0063] Figure 3 The activation energy diagram for the dehydrogenation of methylcyclohexane catalyzed by the catalyst;

[0064] Figure 4 is the X-ray diffraction (XRD) pattern of the catalyst;

[0065] Figure 5 The particle size distribution (TEM) of catalyst #2 is shown;

[0066] Figure 6 This is the particle size distribution (TEM) diagram of catalyst #4. DETAILED DESCRIPTION

[0067] In order to further illustrate the present invention, the Pt-based catalyst provided by the present invention and its preparation method and application are described in detail below in conjunction with examples.

[0068] Example 1

[0069] (I) Preparation of Pt-based catalysts

[0070] 1) Magnesium nitrate hexahydrate and aluminum nitrate nonahydrate are mixed with Mg 2+ and Al 3+ The molar ratio of 2:1 was used for feeding, deionized water was used as the solvent, 50 mL of a 0.6 mol / L mixed salt solution was prepared, and then 27.6 μmol of chloroplatinic acid was added and stirred thoroughly to completely dissolve it.

[0071] 2) Sodium hydroxide and sodium carbonate are reacted with OH - and CO3 2- The molar ratio of 2:1 is used to add materials to prepare 50mL, 2.4mol / L mixed alkali solution, and it is fully stirred to completely dissolve.

[0072] 3) In another beaker, add 25 mL of distilled water, slowly drop the alkaline solution and salt solution into it using a dropper, and continue stirring. Use a pH meter to control the pH of the suspension to 8.

[0073] 4) After all the salt solution has been added, the suspension is transferred to a constant temperature water bath, the crystallization temperature is controlled to 80°C, and the mixture is stirred continuously for crystallization for 12 hours. After the crystallization is completed, the mixture is filtered until the pH of the filtrate is neutral. The filter cake is placed in a 60°C forced air drying oven and dried for 12 hours. The obtained solid powder is transferred to a muffle furnace and calcined at 500°C for 2 hours to obtain a Pt-based catalyst, which is marked as catalyst #1.

[0074] In the catalyst #1 provided in this embodiment, based on the mass of the catalyst being 100%, the mass content of Pt is 0.5 wt%.

[0075] (II) Catalytic dehydrogenation of methylcyclohexane using catalyst #1

[0076] Weigh 50 mg of 1# catalyst and 0.5 g of 40-60 mesh quartz sand and mix them evenly. Place the mixture in a quartz reaction tube, introduce a hydrogen-nitrogen mixed gas with a total volume flow rate of 60 mL / min and a hydrogen volume concentration of 10%, and pretreat at 400° C. for 1 hour. After the pretreatment, set the reactor temperature to 300° C., introduce 15 mL / min nitrogen to purge for 30 minutes, then introduce nitrogen and start the methylcyclohexane feed pump, the feed flow rate is 0.02 mL / min, the volume concentration of the methylcyclohexane feed is 19%, and the methylcyclohexane and nitrogen are premixed in a preheating furnace, and the preheating furnace temperature is 120° C.

[0077] Reaction product monitoring: During the reaction, the products at different reaction times were analyzed. The detection method was as follows: 10 minutes after the raw material methylcyclohexane was introduced, the products of the reaction system were collected every 20 minutes.

[0078] The obtained instantaneous conversion rate of methylcyclohexane and hydrogen generation rate per unit mass of platinum are shown in Table 1.

[0079] Example 2

[0080] (I) Preparation of Pt-based catalysts

[0081] The preparation method is the same as that in Example 1, but the difference is that 38.6 μmol of chloroplatinic acid is added in 1), and the obtained Pt-based catalyst is marked as catalyst #2.

[0082] In the 2# catalyst provided in this embodiment, based on the mass of the catalyst being 100%, the mass content of Pt is 0.7 wt%.

[0083] (II) Catalytic dehydrogenation of methylcyclohexane using catalyst #2

[0084] This method is the same as the method for catalytic dehydrogenation of methylcyclohexane provided in Example 1, but the difference is that the catalyst is 2# catalyst, and the rest is the same as Example 1.

[0085] The reaction product detection method is the same as that in Example 1, and the detection results are shown in Table 1.

[0086] Example 3

[0087] (I) Preparation of Pt-based catalysts

[0088] The preparation method is the same as that in Example 1, but the difference is that 55.2 μmol of chloroplatinic acid is added in 1), and the obtained Pt-based catalyst is marked as catalyst #3.

[0089] In the 3# catalyst provided in this embodiment, based on the mass of the catalyst being 100%, the mass content of Pt is 1 wt%.

[0090] (II) Catalytic dehydrogenation of methylcyclohexane using catalyst #3

[0091] This method is the same as the method for catalytic dehydrogenation of methylcyclohexane provided in Example 1, except that catalyst #3 is used as the catalyst, and the rest is the same as Example 1.

[0092] The reaction product detection method is the same as that in Example 1, and the detection results are shown in Table 1.

[0093] Comparative Example 1

[0094] (I) Preparation of Pt-based catalysts

[0095] This comparative example provides a platinum-based catalyst prepared by an impregnation method using magnesium-aluminum hydrotalcite as a carrier, which is denoted as 4#. The specific preparation method of the catalyst is as follows:

[0096] 1) Magnesium nitrate hexahydrate and aluminum nitrate nonahydrate are mixed with Mg 2+ and Al 3+The molar ratio of 2:1 was used for feeding, and deionized water was used as the solvent to prepare 50mL, 0.6mol / L mixed salt solution to completely dissolve it.

[0097] 2) Sodium hydroxide and sodium carbonate are reacted with OH - and CO3 2- The molar ratio of 2:1 is used to add materials to prepare 50mL, 2.4mol / L mixed alkali solution, and it is fully stirred to completely dissolve.

[0098] 3) In another beaker, add 25 mL of distilled water, slowly drip the mixed alkali solution and mixed salt solution into it using a dropper, and continue stirring. Use a pH meter to control the pH of the suspension to 8.

[0099] 4) After all the salt solution has been added, move the suspension into a constant temperature water bath, control the crystallization temperature to 80°C, and stir continuously for 12 hours. After the crystallization is completed, filter until the pH of the filtrate is neutral. Place the filter cake in a 60°C forced air drying oven and dry it for 12 hours.

[0100] 5) Weigh 0.5 g of the above-mentioned magnesium aluminum hydrotalcite solid powder, add 38.6 μmol of chloroplatinic acid into 1 mL of saturated ammonium chloride solution, mix well, then add the mixture into the above-mentioned magnesium aluminum hydrotalcite solid powder, stir well, place in a 60° C. forced drying oven, and dry for 6 h. Place the dried powder in a muffle furnace and calcine at 500° C. for 2 h.

[0101] In the 4# catalyst provided in this comparative example, based on the mass of the catalyst being 100%, the mass content of Pt is 0.7 wt%.

[0102] (II) Catalytic dehydrogenation of methylcyclohexane using catalyst #4

[0103] This method is the same as the method for catalytic dehydrogenation of methylcyclohexane provided in Example 1, except that the catalyst is the 4# catalyst provided in this comparative example, and the rest is the same as in Example 1.

[0104] The reaction product detection method is the same as that in Example 1, and the detection results are shown in Table 1.

[0105] Table 1 Methylcyclohexane dehydrogenation reaction results

[0106]

[0107]

[0108] Wherein, methylcyclohexane instantaneous conversion rate = (methylcyclohexane instantaneous consumption ÷ methylcyclohexane instantaneous feed amount) × 100%

[0109] Hydrogen generation rate per unit mass of platinum = (methylcyclohexane consumption rate × toluene selectivity × 3) / mass of platinum in the catalyst participating in the reaction

[0110] The present invention adopts the method of online detection to analyze the product composition, and the conversion rate obtained is the instantaneous conversion rate. By comparing the conversion rate of methylcyclohexane in Table 1, it is shown that the catalytic performance of the catalyst for the conversion reaction of methylcyclohexane is 3# catalyst>2# catalyst>1# catalyst>4# catalyst (such as Figure 1 As shown in the figure, catalyst 3# has the highest methylcyclohexane conversion rate, while catalyst 4# prepared by the impregnation method has the worst catalytic performance. The mass content of Pt in catalyst 2# and catalyst 4# is 0.7wt%, but due to the different preparation methods, the catalytic effects of the final catalysts when applied to the conversion reaction of methylcyclohexane are significantly different.

[0111] like Figure 2 As shown, the 2# catalyst has good stability in the dehydrogenation reaction of methylcyclohexane, and the instantaneous conversion rate of methylcyclohexane and the selectivity of toluene are relatively stable.

[0112] like Figure 3 As shown, the catalysts (catalyst #1, catalyst #2, catalyst #3) prepared by the preparation method of the present invention show higher conversion rate and lower activation energy when applied to the conversion reaction of methylcyclohexane compared with catalyst #4 prepared by the impregnation method.

[0113] like Figure 4 As shown, catalyst 1#, catalyst 2#, and catalyst 3# do not have the characteristic peak of Pt, which proves that the Pt particle size in the catalyst is small and is highly dispersed; while catalyst 4# has an obvious characteristic peak of Pt, indicating that the Pt particle size in the catalyst obtained by the traditional impregnation method is large and the atomic utilization rate is low.

[0114] By comparison Figure 5 and Figure 6 The particle size distribution (TEM) diagram shown in FIG. 1 shows that when the two catalysts (catalyst #2 and catalyst #4) have the same Pt ​​loading, the catalyst #2 prepared by the preparation method of the present invention has a smaller particle size and a more uniform size.

[0115] In summary, the preparation method of the present invention introduces a platinum source during the pre-synthesis process of the Pt-based catalyst, using PtCl6 2-The strong electrostatic interaction between the Pt and the magnesium-aluminum hydrotalcite layer (positively charged) and the change of the Pt loading amount realize the microstructure regulation of Pt in the Pt-based catalyst, and apply it to the dehydrogenation reaction of methylcyclohexane to achieve efficient activation of CH and improve the conversion rate of the dehydrogenation reaction of methylcyclohexane. The preparation method of the Pt-based catalyst of the present invention is simple in process, easy to operate, and suitable for industrial production. The Pt particle size in the Pt-based catalyst of the present invention is small, presents a highly dispersed state, and has a high atomic utilization rate. When used for the dehydrogenation reaction of methylcyclohexane, it has high catalytic activity and good stability.

[0116] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for producing hydrogen by dehydrogenating methylcyclohexane, characterized in that: A Pt-based catalyst is used as a dehydrogenation catalyst to directly contact and react with a reaction gas containing methylcyclohexane to obtain hydrogen and toluene; The preparation method of the Pt-based catalyst comprises the following steps: mixing an aqueous solution I containing magnesium ions, aluminum ions and platinum ions with an aqueous solution II containing a hydroxide-containing alkaline compound and a carbonate, and reacting to obtain a Pt-based catalyst; the pH value of the reaction is 7-8; during the mixing of the aqueous solution I with the aqueous solution II, the pH value of the system is controlled to remain unchanged; the platinum ions are provided by one or more of chloroplatinic acid, potassium chloroplatinate, and ammonium chloroplatinate; and after the reaction is completed, crystallization and calcination are also included; The temperature of the methylcyclohexane dehydrogenation reaction is 300°C.

2. The method for producing hydrogen by dehydrogenating methylcyclohexane according to claim 1, characterized in that: The magnesium ion is provided by one or more of magnesium nitrate hexahydrate, magnesium acetate tetrahydrate, and magnesium chloride; The aluminum ions are provided by one or more of aluminum nitrate nonahydrate, aluminum chloride hexahydrate, and anhydrous aluminum chloride.

3. The method for producing hydrogen by dehydrogenating methylcyclohexane according to claim 1, characterized in that: The molar ratio of magnesium ion to aluminum ion is (1-5):1; The sum of the molar concentrations of the magnesium ions and the aluminum ions is 0.1 to 1 mol / L; The molar concentration of the platinum ions is 0.1-20 mmol / L; The molar ratio of the platinum ions to the magnesium ions is (1-25):1000.

4. The method for producing hydrogen by dehydrogenating methylcyclohexane according to claim 1, characterized in that: The hydroxide-containing alkaline compound is selected from sodium hydroxide or potassium hydroxide; The carbonate is selected from sodium carbonate or potassium carbonate.

5. The method for producing hydrogen by dehydrogenating methylcyclohexane according to claim 1, characterized in that: The molar ratio of the hydroxide-containing alkaline compound to the carbonate is (1-5):1; The sum of the molar concentrations of the hydroxide-containing alkaline compound and the carbonate is 1 to 5 mol / L.

6. The method for producing hydrogen by dehydrogenating methylcyclohexane according to claim 1, characterized in that: The volume ratio of the aqueous solution I to the aqueous solution II is (0.5~4):

1.

7. The method for producing hydrogen by dehydrogenating methylcyclohexane according to claim 1, characterized in that: After the reaction is completed, the process further includes crystallization and calcination; The crystallization temperature is 50-100°C; The crystallization time is 5 to 24 h; The calcining atmosphere is selected from one or more of vacuum, nitrogen, argon, helium and air; The calcination temperature is 300-800°C; The calcination time is 2 to 6 h.

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