Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst and preparation method thereof

Abstract

The invention discloses a Sm-doped modified Ni / de-USY catalyst for ammonia hydrogen production. The Sm-doped modified Ni / de-USY catalyst is prepared from the following raw materials in percentage by mass: 97.82%-98.85% of a USY molecular sieve, 0.5%-1.4% of a nickel compound and 0.22%-0.79% of a samarium oxide. The invention also discloses a preparation method of the Sm-doped modified Ni / de-USY catalyst for hydrogen production from ammonia, which comprises the following steps: performing hydrothermal pretreatment on the USY molecular sieve, performing acid treatment, and preparing the catalyst for hydrogen production from ammonia by utilizing an ultrasonic-assisted equivalent-volume impregnation method. The catalyst for hydrogen production from ammonia can efficiently decompose ammonia gas and is high in hydrogen production efficiency, and due to the fact that active metal is highly dispersed on the de-USY surface, high relative crystallinity is kept, and the pore channel structure of the complete Y molecular sieve is kept, the catalyst for hydrogen production from ammonia has high stability, and the catalytic effect can be prevented from being affected.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical hydrogen storage material catalysis, and specifically relates to a Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst and a preparation method thereof. Background Art

[0002] Hydrogen is a zero-carbon, high-energy-density fuel that is expected to replace fossil fuels for power generation and clean energy. However, hydrogen still faces huge challenges in production, transportation and storage. Ammonia is a promising hydrogen storage material that can easily overcome the difficulties associated with hydrogen storage and transportation. Therefore, ammonia decomposition to produce hydrogen has attracted increasing attention as a green and environmentally friendly technology. Conventional ammonia decomposition to produce hydrogen uses a Y-type molecular sieve with an ultra-stabilized skeleton structure, namely USY molecular sieve, for efficient release of hydrogen in hydrogen storage materials. Due to the small pore size, this molecular sieve material is prone to problems such as uneven particle size distribution and poor high-temperature catalytic activity. The modification of the molecular sieve is not enough to completely solve these problems. Load modification is required to improve its performance. Different metal loading methods will result in different metal dispersions and particle sizes. Some metal loading methods such as precipitation deposition method, sol-gel method, colloidal deposition method and ion exchange method will cause metal ion leaching, agglomeration and precipitation, thereby limiting its ammonia decomposition activity.

[0003] For example, USY molecular sieve is only dealuminated. Dealumination refers to the use of water and aluminum oxide in zeolite to undergo hydrolysis modification under high temperature conditions, and the use of acid to react with aluminum in zeolite to modify, which is easy to change the acidity of zeolite molecular sieve, which may affect its performance in certain specific catalytic reactions, generate a small number of mesoporous structures, and consume too much energy. In the dealumination process, when the pH of the inorganic acid is less than 2.3, the inorganic acid can effectively remove the framework aluminum. If the acidity is strong, it is easy to destroy the framework structure of USY molecular sieve, or even collapse, resulting in low crystallinity of the molecular sieve; if the acidity is too low, the dealumination degree is insufficient, resulting in the number and distribution of catalyst active sites, decomposition of ammonia, and low hydrogen production efficiency.

[0004] Furthermore, the preparation of USY molecular sieve supported metal catalysts is highly dependent on the introduction of a metal content of less than 1 wt%, which often results in insufficient catalyst active centers during the catalytic process and a low yield of the target product.

[0005] In short, the research on USY molecular sieve-loaded metal catalysts is still in the exploratory stage, and there are many problems that need to be solved, such as the coordination interaction between the electronic properties of single-atom metals and the surface of molecular sieve pores, and the difficulty for gas molecules to enter the microporous channels of the molecular sieve and contact the metal active sites, which will affect the catalytic effect. Therefore, there is an urgent need for an efficient, highly stable USY molecular sieve-loaded metal catalyst and its preparation method. Summary of the invention

[0006] The object of the present invention is to overcome the deficiencies in the above-mentioned prior art and provide a Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst, which can efficiently decompose ammonia and has a high hydrogen production efficiency; the active metal loaded on the USY molecular sieve in the ammonia hydrogen production catalyst is highly dispersed on the de-USY surface and maintains a high relative crystallinity; the ammonia hydrogen production catalyst prepared by the present invention can also maintain the pore structure of the complete Y molecular sieve, has high stability, and can avoid the catalytic effect being affected.

[0007] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst, characterized in that the Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst comprises a USY molecular sieve and a nickel compound and a samarium oxide loaded on the USY molecular sieve; the mass percentage of the USY molecular sieve is 97.82% to 98.85%, the mass percentage of the nickel compound is 0.5% to 1.4%, and the mass percentage of the samarium oxide is 0.22% to 0.79%.

[0008] The above-mentioned Sm-doped modified Ni / de-USY ammonia to hydrogen catalyst is characterized in that the samarium oxide is Sm2O3, the nickel compounds are NiO, NiAl2O4 and other nickel compounds, among which the mass percentage of NiO is 73% to 84%, the mass percentage of NiAl2O4 is 12% to 25%, and the mass percentage of other nickel compounds is 0.1% to 5%, and the other nickel compounds are NiAlOOH and Ni3Al.

[0009] In order to obtain the above-mentioned Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst, the present invention also provides a preparation method of the Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst, comprising the following steps:

[0010] Step 1: Perform high-temperature hydrothermal pretreatment on the USY molecular sieve. The specific operation process is: put the USY molecular sieve into a quartz tube, heat the high-temperature tube furnace, and then introduce an inert gas as a carrier gas into the quartz tube, and at the same time introduce gas into the quartz tube through a water saturator to obtain a pretreated USY molecular sieve;

[0011] Step 2, the pretreated USY molecular sieve obtained in step 1 is subjected to dealumination reaction, and the specific operation process is: mixing the pretreated USY molecular sieve with an acid to obtain a mixture; stirring the mixture to obtain acid-treated USY; repeatedly filtering and washing the acid-treated USY with water until a pH meter detects that the acid-treated USY is neutral to obtain a modified USY molecular sieve; drying the modified USY molecular sieve to obtain de-USY;

[0012] Step 3, placing the de-USY obtained in step 2 in a nickel nitrate solution for ultrasonic-assisted equal-volume impregnation to obtain impregnated de-USY, and then placing the impregnated de-USY in a magnetic stirrer for stirring to obtain a solid-liquid mixture of de-USY loaded with nickel nitrate;

[0013] Step 4, allowing the nickel nitrate-loaded de-USY solid-liquid mixture obtained in step 3 to stand and precipitate at room temperature, placing the precipitated nickel nitrate-loaded de-USY in a vacuum drying oven to dry to obtain dried nickel nitrate-loaded de-USY, and then placing the dried nickel nitrate-loaded de-USY in a muffle furnace for calcination to obtain nickel-modified de-USY;

[0014] Step 5, placing the nickel-modified de-USY obtained in step 4 into a high-temperature tube furnace, heating the high-temperature tube furnace, and then introducing a reducing gas into the high-temperature tube furnace to obtain a Ni / de-USY catalyst;

[0015] Step 6: Place the Ni / de-USY catalyst obtained in step 5 in a Sm(NO3)3 solution for ultrasonic-assisted equal-volume impregnation, and then place the impregnated Ni / de-USY catalyst in a magnetic stirrer for stirring to obtain a Sm2O3-loaded Ni / de-USY solid-liquid mixture.

[0016] Step seven, the Sm2O3-loaded Ni / de-USY solid-liquid mixture obtained in step six is ​​placed at room temperature for static precipitation, the wet Sm2O3-loaded Ni / de-USY solid obtained by precipitation is placed in a vacuum drying oven for drying to obtain a dry product, and the dry product is then placed in a muffle furnace for roasting to obtain a finished Sm2O3-Ni / de-USY catalyst, i.e., a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst.

[0017] The above-mentioned method for preparing a Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst is characterized in that the heating in step one is to 600°C; the inert gas is nitrogen, the nitrogen flow rate is 100mL / min, the gas introduced into the water saturator is water vapor, and the water vapor introduction time is 1.5h to 3h.

[0018] The above-mentioned method for preparing a Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst is characterized in that the acid in step 2 is benzoic acid, and the molar concentration of the benzoic acid is 0.8 mol / L to 1.0 mol / L; the mixing ratio of the pretreated USY molecular sieve and the acid is: 1 g of the pretreated USY molecular sieve and 5 ml to 10 mL of the benzoic acid solution, the stirring is magnetic stirring, the stirring condition is a constant temperature water bath at 90°C, and the stirring time is 3 hours; the water is deionized water; the drying is vacuum drying, the vacuum drying temperature is 70°C, and the drying time is 6 hours.

[0019] The above-mentioned method for preparing a Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst is characterized in that the molar concentration of the nickel nitrate solution in step three is 1.5 mol / L to 1.8 mol / L.

[0020] The above-mentioned method for preparing a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst is characterized in that the calcination temperature in step 4 is 500° C. and the calcination time is 5 hours.

[0021] In the above-mentioned method for preparing a Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst, the high-temperature tubular furnace in step five is heated to 700° C., the reducing gas is hydrogen, the hydrogen introduction rate is 100 mL / min, and the introduction time is 2 h.

[0022] In the above-mentioned method for preparing a Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst, the molar concentration of the Sm(NO3)3 solution in step six is ​​0.1 mol / L.

[0023] In the above-mentioned method for preparing a Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst, the drying temperature of the vacuum drying in step seven is 110° C., and the drying time is 12 h; the calcination temperature of the muffle furnace calcination is 500° C., and the calcination time is 5 h.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. The preparation method of the ammonia hydrogen production catalyst of the present invention comprises the following steps: performing a 600°C hydrothermal pretreatment on the USY molecular sieve, and then performing a dechlorination reaction using benzoic acid. Compared with the single 600°C hydrothermal pretreatment, the silicon-aluminum ratio of the USY molecular sieve is significantly improved by 56.8%, the dealumination effect is obvious, and the surface acidity and pore structure of the molecular sieve are changed, so that the efficiency and activity of the ammonia decomposition reaction are significantly improved.

[0026] 2. The preparation method of the ammonia hydrogen production catalyst of the present invention adopts USY molecular sieve, which is obtained by modification of NaY and is one of the Y-type molecular sieves, belonging to the faujasite type. The faujasite cage is the main hole, which is connected with four other identical faujasite cages through a twelve-membered oxygen ring. The orifice diameter of the twelve-membered ring is 0.74nm, which is the main channel of the Y-type molecular sieve. The Y-type molecular sieve has a high silicon-aluminum ratio and strong hydrothermal stability.

[0027] 3. The preparation method of the ammonia-to-hydrogen catalyst of the present invention uses a modified de-USY molecular sieve with obvious connected mesopores. The improvement of the connectivity between the pores is beneficial to improving the accessibility of the active center of the molecular sieve and greatly improving the diffusion and mass transfer performance of the active metal in the pores.

[0028] 4. The preparation method of the ammonia hydrogen production catalyst of the present invention adopts the ultrasound-assisted equal volume impregnation method to load the metal to prepare the ammonia hydrogen production catalyst. Compared with the catalyst loaded with metal by the impregnation method and the hydrothermal synthesis method, the active metal loading amount is increased, the metal loading is uniform, and the energy consumption required for the experiment is greatly reduced; and the Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst finished product can maintain a high relative crystallinity and maintain the pore structure of the complete Y zeolite without structural collapse, thereby significantly improving the efficiency and activity of the ammonia decomposition reaction.

[0029] 5. Among the ammonia-to-hydrogen catalysts of the present invention, the Ni / de-USY catalyst modified by Sm2O3 has good catalytic activity, which is mainly reflected in the high dispersion of the active phase Sm2O3, the improvement of the mobility of the active species and the enhancement of Lewis acidity, which greatly improves the catalyst activity and thus improves the product yield.

[0030] The present invention is further described in detail below through the accompanying drawings and examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a flow chart for preparing a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst;

[0032] Figure 2 This is a flow chart of an equipment for a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst in the present invention;

[0033] Figure 3 This is an electron microscope image of the Sm2O3-Ni / de-USY finished product prepared by the present invention;

[0034] Figure 4 This is an electron microscope picture of the USY molecular sieve of the present invention;

[0035] Figure 5A comparison diagram of ammonia decomposition efficiency between the de-USY molecular sieve of the present invention and the dealuminated USY molecular sieve treated with benzoic acid only;

[0036] Figure 6 This is a comparison chart of ammonia decomposition efficiency between Sm2O3-Ni / de-USY obtained by the ultrasonic-assisted equal volume impregnation method of the present invention and Sm2O3-Ni / de-USY synthesized by the normal impregnation method. DETAILED DESCRIPTION

[0037] Through Examples 1-9, a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst and a preparation method thereof provided by the present invention are described in detail:

[0038] Example 1

[0039] The present embodiment provides a Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst, comprising a USY molecular sieve, a nickel compound supported on a USY carrier, and a samarium oxide. The mass percentage of the USY molecular sieve in the supported ammonia decomposition catalyst is 98.85%, the mass percentage of the nickel compound is 0.5%, and the mass percentage of the samarium oxide is 0.65%; the samarium oxide is Sm203 (samarium trioxide), and the nickel compound is mainly NiO (nickel oxide) and NiAl2O4 (nickel aluminum spinel); in the nickel compound, the mass percentage of NiO is 73% to 84%, and the mass percentage of NiAl2O4 is 12% to 25%.

[0040] The nickel compound also includes other nickel compounds, the mass percentage of the other nickel compounds is 0.1% to 5%, and the other nickel compounds are NiAlOOH (nickel aluminate) and Ni3Al (nickel aluminide).

[0041] The present embodiment provides a method for preparing a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst, comprising the following steps:

[0042] Step 1: Introduce quartz sand into the fixed bed catalyst bed to fix 5g USY molecular sieve, heat it in a high-temperature tubular furnace, the tubular furnace carrier gas is nitrogen, the tubular furnace carrier gas flow rate is 100mL / min, the gas introduced into the water saturator is water vapor, the reaction temperature is 600°C, the reaction time is 1.5h, and obtain the pretreated USY molecular sieve;

[0043] Step 2: Dealumination reaction is performed on the pretreated USY molecular sieve obtained in step 1. The specific operation process is: mixing the pretreated USY molecular sieve with 0.8 mol / L benzoic acid to obtain a mixture; magnetically stirring the mixture in a constant temperature water bath at 90°C for 3 hours to obtain acid-treated USY; repeatedly filtering and washing the acid-treated USY with deionized water until a pH meter detects that the acid-treated USY is neutral to obtain a modified USY molecular sieve; placing the modified USY molecular sieve in a vacuum drying oven at 70°C and drying for 6 hours to obtain de-USY; the mixing ratio is 1 g of the pretreated USY molecular sieve and 10 mL of the benzoic acid solution.

[0044] Step 3, placing the de-USY in step 2 in a nickel nitrate solution with a molar concentration of 1.5 mol / L for ultrasonic-assisted equal volume impregnation, and then placing it in a magnetic stirrer for stirring, so that the nickel nitrate is loaded in the pores of the de-USY, to obtain a solid-liquid mixture of de-USY loaded with nickel nitrate;

[0045] Step 4: The nickel nitrate-loaded de-USY solid-liquid mixture obtained in step 3 is allowed to settle at room temperature, the wet nickel nitrate-loaded de-USY solid obtained by precipitation is placed in a vacuum drying oven for drying, and then placed in a muffle furnace at 500° C. for calcination for 5 hours to obtain nickel-modified de-USY;

[0046] Step 5: Place the nickel-modified de-USY obtained in step 4 into a high-temperature tube furnace, then heat the high-temperature tube furnace to 700°C, introduce hydrogen, and reduce the Ni(NO3)2 loaded in the de-USY pores to nickel compounds to form a Ni / de-USY catalyst; the gas flow rate is 100 mL / min, and the hydrogen introduction time is 2 h.

[0047] Step 6: Place the Ni / de-USY catalyst described in step 5 in a samarium nitrate solution with a molar concentration of 0.1 mol / L for ultrasonic-assisted equal volume impregnation to load samarium oxide in the pores of the Ni / de-USY, and then place it in a magnetic stirrer for stirring to obtain a Ni / de-USY solid-liquid mixture loaded with Sm2O3.

[0048] Step seven, the Sm2O3-loaded Ni / de-USY solid-liquid mixture obtained in step six is ​​placed at room temperature for static precipitation, the precipitated wet Sm2O3-loaded Ni / de-USY solid is placed in a vacuum drying oven at 110°C for 12 hours, and then placed in a muffle furnace for calcination at 500°C for 5 hours to obtain a finished Sm2O3-Ni / de-USY catalyst, i.e., a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst.

[0049] Example 2

[0050] The present embodiment provides a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst, which includes a USY molecular sieve carrier, a nickel compound supported on the USY carrier, and a samarium oxide. The mass percentage of USY zeolite in the supported ammonia decomposition catalyst is 98.57%, the mass percentage of the nickel compound is 0.7%, and the mass percentage of the samarium oxide is 0.73%.

[0051] The samarium oxide is Sm2O3, and the nickel compound is mainly NiO and NiAl2O4; among the nickel compounds, the mass percentage of NiO is 73% to 84%, and the mass percentage of NiAl2O4 is 12% to 25%.

[0052] The nickel compound also includes other nickel compounds, the mass percentage of the other nickel compounds is 0.1% to 5%, and the other nickel compounds are NiAlOOH and Ni3Al.

[0053] The present embodiment provides a method for preparing a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst, comprising the following steps:

[0054] Step 1: Introduce quartz sand into the fixed bed catalyst bed to fix 5g USY molecular sieve, heat in a high-temperature tubular furnace, the tubular furnace carrier gas is nitrogen, the tubular furnace carrier gas flow rate is 100mL / min, the gas introduced into the water saturator is water vapor, the reaction temperature is 600°C, the reaction time is 2h, and a pretreated USY molecular sieve is obtained;

[0055] Step 2: Dealumination reaction is performed on the pretreated USY molecular sieve obtained in step 1. The specific operation process is: mixing the pretreated USY molecular sieve with 1 mol / L benzoic acid to obtain a mixture; magnetically stirring the mixture in a constant temperature water bath at 90°C for 3 hours to obtain acid-treated USY; repeatedly filtering and washing the acid-treated USY with deionized water until a pH meter detects that the acid-treated USY is neutral to obtain a modified USY molecular sieve; placing the modified USY molecular sieve in a vacuum drying oven at 70°C and drying for 6 hours to obtain de-USY; the mixing ratio is 1 g of the pretreated USY molecular sieve and 5 mL of the benzoic acid solution.

[0056] Step 3, placing the de-USY in step 2 in a nickel nitrate solution with a molar concentration of 1.6 mol / L for ultrasonic-assisted equal volume impregnation, and then placing it in a magnetic stirrer for stirring, so that the nickel nitrate is loaded in the pores of the de-USY, to obtain a solid-liquid mixture of de-USY loaded with nickel nitrate;

[0057] Step 4: The nickel nitrate-loaded de-USY solid-liquid mixture obtained in step 3 is allowed to settle at room temperature, the wet nickel nitrate-loaded de-USY solid obtained by precipitation is placed in a vacuum drying oven for drying, and then placed in a muffle furnace at 500° C. for calcination for 5 hours to obtain nickel-modified de-USY;

[0058] Step 5: Place the nickel-modified de-USY obtained in step 4 into a high-temperature tube furnace, then heat the high-temperature tube furnace to 700°C, introduce hydrogen, and reduce the Ni(NO3)2 loaded in the de-USY pores to nickel compounds to form a Ni / de-USY catalyst; the gas flow rate is 100 mL / min, and the hydrogen introduction time is 2 h.

[0059] Step 6: Place the Ni / de-USY catalyst described in step 5 in a samarium nitrate solution with a molar concentration of 0.1 mol / L for ultrasonic-assisted equal volume impregnation to load samarium oxide in the pores of the Ni / de-USY, and then place it in a magnetic stirrer for stirring to obtain a Ni / de-USY solid-liquid mixture loaded with Sm2O3.

[0060] Step seven, the Sm2O3-loaded Ni / de-USY solid-liquid mixture obtained in step six is ​​placed at room temperature for static precipitation, the precipitated wet Sm2O3-loaded Ni / de-USY solid is placed in a vacuum drying oven at 110°C for 12 hours, and then placed in a muffle furnace for calcination at 500°C for 5 hours to obtain a finished Sm2O3-Ni / de-USY catalyst, i.e., a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst.

[0061] Example 3

[0062] The present embodiment provides a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst, which includes a USY molecular sieve carrier, a nickel compound supported on the USY carrier, and a samarium oxide. The mass percentage of USY zeolite in the supported ammonia decomposition catalyst is 98.68%, the mass percentage of the nickel compound is 0.9%, and the mass percentage of the samarium oxide is 0.42%.

[0063] The samarium oxide is Sm2O3, and the nickel compound is mainly NiO and NiAl2O4; among the nickel compounds, the mass percentage of NiO is 73% to 84%, and the mass percentage of NiAl2O4 is 12% to 25%.

[0064] The nickel compound also includes other nickel compounds, the mass percentage of the other nickel compounds is 0.1% to 5%, and the other nickel compounds are NiAlOOH and Ni3Al.

[0065] The present embodiment provides a method for preparing a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst, comprising the following steps:

[0066] Step 1: Introduce quartz sand into the fixed bed catalyst bed to fix 5g USY molecular sieve, heat in a high-temperature tubular furnace, the tubular furnace carrier gas is nitrogen, the tubular furnace carrier gas flow rate is 100mL / min, the gas introduced into the water saturator is water vapor, the reaction temperature is 600°C, the reaction time is 3h, and a pretreated USY molecular sieve is obtained;

[0067] Step 2: Dealumination reaction is performed on the pretreated USY molecular sieve obtained in step 1. The specific operation process is: mixing the pretreated USY molecular sieve with 1 mol / L benzoic acid to obtain a mixture; magnetically stirring the mixture in a constant temperature water bath at 90°C for 3 hours to obtain acid-treated USY; repeatedly filtering and washing the acid-treated USY with deionized water until a pH meter detects that the acid-treated USY is neutral to obtain a modified USY molecular sieve; placing the modified USY molecular sieve in a vacuum drying oven at 70°C and drying for 6 hours to obtain de-USY; the mixing ratio is 1 g of the pretreated USY molecular sieve and 5 mL of the benzoic acid solution.

[0068] Step 3, placing the de-USY in step 2 in a nickel nitrate solution with a molar concentration of 1.8 mol / L for ultrasonic-assisted equal volume impregnation, and then placing it in a magnetic stirrer for stirring, so that the nickel nitrate is loaded in the pores of the de-USY, to obtain a solid-liquid mixture of de-USY loaded with nickel nitrate;

[0069] Step 4: The nickel nitrate-loaded de-USY solid-liquid mixture obtained in step 3 is allowed to settle at room temperature, the wet nickel nitrate-loaded de-USY solid obtained by precipitation is placed in a vacuum drying oven for drying, and then placed in a muffle furnace at 500° C. for calcination for 5 hours to obtain nickel-modified de-USY;

[0070] Step 5: Place the nickel-modified de-USY obtained in step 4 into a high-temperature tube furnace, then heat the high-temperature tube furnace to 700°C, introduce hydrogen, and reduce the Ni(NO3)2 loaded in the de-USY pores to nickel compounds to form a Ni / de-USY catalyst; the gas flow rate is 100 mL / min, and the hydrogen introduction time is 2 h.

[0071] Step 6: Place the Ni / de-USY catalyst described in step 5 in a samarium nitrate solution with a molar concentration of 0.1 mol / L for ultrasonic-assisted equal volume impregnation to load samarium oxide in the pores of the Ni / de-USY, and then place it in a magnetic stirrer for stirring to obtain a Ni / de-USY solid-liquid mixture loaded with Sm2O3.

[0072] Step seven, the Sm2O3-loaded Ni / de-USY solid-liquid mixture obtained in step six is ​​placed at room temperature for static precipitation, the precipitated wet Sm2O3-loaded Ni / de-USY solid is placed in a vacuum drying oven at 110°C for 12 hours, and then placed in a muffle furnace for calcination at 500°C for 5 hours to obtain a finished Sm2O3-Ni / de-USY catalyst, i.e., a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst.

[0073] Example 4

[0074] The present embodiment provides a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst, which includes a USY molecular sieve carrier, a nickel compound supported on the USY carrier, and a samarium oxide. The mass percentage of USY zeolite in the supported ammonia decomposition catalyst is 97.82%, the mass percentage of the nickel compound is 1.4%, and the mass percentage of the samarium oxide is 0.78%.

[0075] The samarium oxide is Sm2O3, and the nickel compound is mainly NiO and NiAl2O4; among the nickel compounds, the mass percentage of NiO is 73% to 84%, and the mass percentage of NiAl2O4 is 12% to 25%.

[0076] The nickel compound also includes other nickel compounds, the mass percentage of the other nickel compounds is 0.1% to 5%, and the other nickel compounds are NiAlOOH and Ni3A1.

[0077] The present embodiment provides a method for preparing a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst, comprising the following steps:

[0078] Step 1: Introduce quartz sand into the fixed bed catalyst bed to fix 5g USY molecular sieve, heat in a high-temperature tubular furnace, the tubular furnace carrier gas is nitrogen, the tubular furnace carrier gas flow rate is 100mL / min, the gas introduced into the water saturator is water vapor, the reaction temperature is 600°C, the reaction time is 1.5h, and obtain the pretreated USY molecular sieve;

[0079] Step 2: Dealumination reaction is performed on the pretreated USY molecular sieve obtained in step 1. The specific operation process is: mixing the pretreated USY molecular sieve with 0.9 mol / L benzoic acid to obtain a mixture; magnetically stirring the mixture in a constant temperature water bath at 90°C for 3 hours to obtain acid-treated USY; repeatedly filtering and washing the acid-treated USY with deionized water until the pH meter detects that the acid-treated USY is neutral to obtain a modified USY molecular sieve; placing the modified USY molecular sieve in a vacuum drying oven at 70°C and drying for 6 hours to obtain de-USY; the mixing ratio is 1g of the pretreated USY molecular sieve and 10mL of the benzoic acid solution.

[0080] Step 3, placing the de-USY in step 2 in a nickel nitrate solution with a molar concentration of 1.7 mol / L for ultrasonic-assisted equal volume impregnation, and then placing it in a magnetic stirrer for stirring, so that the nickel nitrate is loaded in the pores of the de-USY, to obtain a solid-liquid mixture of de-USY loaded with nickel nitrate;

[0081] Step 4: The nickel nitrate-loaded de-USY solid-liquid mixture obtained in step 3 is allowed to settle at room temperature, the wet nickel nitrate-loaded de-USY solid obtained by precipitation is placed in a vacuum drying oven for drying, and then placed in a muffle furnace at 500° C. for calcination for 5 hours to obtain nickel-modified de-USY;

[0082] Step 5: Place the nickel-modified de-USY obtained in step 4 into a high-temperature tube furnace, then heat the high-temperature tube furnace to 700°C, introduce hydrogen, and reduce the Ni(NO3)2 loaded in the de-USY pores to nickel compounds to form a Ni / de-USY catalyst; the gas flow rate is 100 mL / min, and the hydrogen introduction time is 2 h.

[0083] Step 6: Place the Ni / de-USY catalyst described in step 5 in a samarium nitrate solution with a molar concentration of 0.1 mol / L for ultrasonic-assisted equal volume impregnation to load samarium oxide in the pores of the Ni / de-USY, and then place it in a magnetic stirrer for stirring to obtain a Ni / de-USY solid-liquid mixture loaded with Sm2O3.

[0084] Step seven, the Sm2O3-loaded Ni / de-USY solid-liquid mixture obtained in step six is ​​placed at room temperature for static precipitation, the precipitated wet Sm2O3-loaded Ni / de-USY solid is placed in a vacuum drying oven at 110°C for 12 hours, and then placed in a muffle furnace for calcination at 500°C for 5 hours to obtain a finished Sm2O3-Ni / de-USY catalyst, i.e., a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst.

[0085] Example 5

[0086] The present embodiment provides a Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst, comprising a USY molecular sieve carrier, a nickel compound supported on the USY carrier, and a samarium oxide, wherein the mass percentage of USY zeolite in the supported ammonia decomposition catalyst is 98.05%, the mass percentage of the nickel compound is 1.3%, and the mass percentage of the samarium oxide is 0.65%.

[0087] The samarium oxide is Sm2O3, and the nickel compound is mainly NiO and NiAl2O4; among the nickel compounds, the mass percentage of NiO is 73% to 84%, and the mass percentage of NiAl2O4 is 12% to 25%.

[0088] The nickel compound also includes other nickel compounds, the mass percentage of the other nickel compounds is 0.1% to 5%, and the other nickel compounds are NiAlOOH and Ni3Al.

[0089] The preparation method of a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst provided in this embodiment comprises the following steps:

[0090] Step 1: Introduce quartz sand into the fixed bed catalyst bed to fix 5g USY molecular sieve, heat in a high-temperature tubular furnace, the tubular furnace carrier gas is nitrogen, the tubular furnace carrier gas flow rate is 100mL / min, the gas introduced into the water saturator is water vapor, the reaction temperature is 600°C, the reaction time is 2h, and a pretreated USY molecular sieve is obtained;

[0091] Step 2: Dealumination reaction is performed on the pretreated USY molecular sieve obtained in step 1. The specific operation process is: mixing the pretreated USY molecular sieve with 0.8 mol / L benzoic acid to obtain a mixture; magnetically stirring the mixture in a constant temperature water bath at 90°C for 3 hours to obtain acid-treated USY; repeatedly filtering and washing the acid-treated USY with deionized water until the pH meter detects that the acid-treated USY is neutral to obtain a modified USY molecular sieve; placing the modified USY molecular sieve in a vacuum drying oven at 70°C and drying for 6 hours to obtain de-USY; the mixing ratio is 1 g of the pretreated USY molecular sieve and 5 mL of the benzoic acid solution.

[0092] Step 3, placing the de-USY in step 2 in a nickel nitrate solution with a molar concentration of 1.6 mol / L for ultrasonic-assisted equal volume impregnation, and then placing it in a magnetic stirrer for stirring, so that the nickel nitrate is loaded in the pores of the de-USY, to obtain a solid-liquid mixture of de-USY loaded with nickel nitrate;

[0093] Step 4: The nickel nitrate-loaded de-USY solid-liquid mixture obtained in step 3 is allowed to settle at room temperature, the wet nickel nitrate-loaded de-USY solid obtained by precipitation is placed in a vacuum drying oven for drying, and then placed in a muffle furnace at 500° C. for calcination for 5 hours to obtain nickel-modified de-USY;

[0094] Step 5: Place the nickel-modified de-USY obtained in step 4 into a high-temperature tube furnace, then heat the high-temperature tube furnace to 700°C, introduce hydrogen, and reduce the Ni(NO3)2 loaded in the de-USY pores to nickel compounds to form a Ni / de-USY catalyst; the gas flow rate is 100 mL / min, and the hydrogen introduction time is 2 h.

[0095] Step 6: Place the Ni / de-USY catalyst described in step 5 in a samarium nitrate solution with a molar concentration of 0.1 mol / L for ultrasonic-assisted equal volume impregnation to load samarium oxide in the pores of the Ni / de-USY, and then place it in a magnetic stirrer for stirring to obtain a Ni / de-USY solid-liquid mixture loaded with Sm2O3.

[0096] Step seven, the Sm2O3-loaded Ni / de-USY solid-liquid mixture obtained in step six is ​​placed at room temperature for static precipitation, the precipitated wet Sm2O3-loaded Ni / de-USY solid is placed in a vacuum drying oven at 110°C for 12 hours, and then placed in a muffle furnace for calcination at 500°C for 5 hours to obtain a finished Sm2O3-Ni / de-USY catalyst, i.e., a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst.

[0097] Example 6

[0098] The present embodiment provides a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst, comprising a USY molecular sieve carrier, a nickel compound supported on the USY carrier, and a samarium oxide. The mass percentage of USY zeolite in the supported ammonia decomposition catalyst is 98.28%, the mass percentage of the nickel compound is 1.0%, and the mass percentage of the samarium oxide is 0.72%.

[0099] The samarium oxide is Sm2O3, and the nickel compound is mainly NiO and NiAl2O4; among the nickel compounds, the mass percentage of NiO is 73% to 84%, and the mass percentage of NiAl2O4 is 12% to 25%.

[0100] The nickel compound also includes other nickel compounds, the mass percentage of the other nickel compounds is 0.1% to 5%, and the other nickel compounds are NiAlOOH and Ni3Al.

[0101] A method for preparing a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst comprises the following steps:

[0102] Step 1: Introduce quartz sand into the fixed bed catalyst bed to fix 5g USY molecular sieve, heat in a high-temperature tubular furnace, the tubular furnace carrier gas is nitrogen, the tubular furnace carrier gas flow rate is 100mL / min, the gas introduced into the water saturator is water vapor, the reaction temperature is 600°C, the reaction time is 3h, and a pretreated USY molecular sieve is obtained;

[0103] Step 2: Dealumination reaction is performed on the pretreated USY molecular sieve obtained in step 1. The specific operation process is: mixing the pretreated USY molecular sieve with 1 mol / L benzoic acid to obtain a mixture; magnetically stirring the mixture in a constant temperature water bath at 90°C for 3 hours to obtain acid-treated USY; repeatedly filtering and washing the acid-treated USY with deionized water until the pH meter detects that the acid-treated USY is neutral to obtain a modified USY molecular sieve; placing the modified USY molecular sieve in a vacuum drying oven at 70°C and drying for 6 hours to obtain de-USY; the mixing ratio is 1g of the pretreated USY molecular sieve and 8mL of the benzoic acid solution.

[0104] Step 3, placing the de-USY in step 2 in a nickel nitrate solution with a molar concentration of 1.7 mol / L for ultrasonic-assisted equal volume impregnation, and then placing it in a magnetic stirrer for stirring, so that the nickel nitrate is loaded in the pores of the de-USY, to obtain a solid-liquid mixture of de-USY loaded with nickel nitrate;

[0105] Step 4: The nickel nitrate-loaded de-USY solid-liquid mixture obtained in step 3 is allowed to settle at room temperature, the wet nickel nitrate-loaded de-USY solid obtained by precipitation is placed in a vacuum drying oven for drying, and then placed in a muffle furnace at 500° C. for calcination for 5 hours to obtain nickel-modified de-USY;

[0106] Step 5: Place the nickel-modified de-USY obtained in step 4 into a high-temperature tube furnace, then heat the high-temperature tube furnace to 700°C, introduce hydrogen, and reduce the Ni(NO3)2 loaded in the de-USY pores to nickel compounds to form a Ni / de-USY catalyst; the gas flow rate is 100 mL / min, and the hydrogen introduction time is 2 h.

[0107] Step 6: Place the Ni / de-USY catalyst described in step 5 in a samarium nitrate solution with a molar concentration of 0.1 mol / L for ultrasonic-assisted equal volume impregnation to load samarium oxide in the pores of the Ni / de-USY, and then place it in a magnetic stirrer for stirring to obtain a Ni / de-USY solid-liquid mixture loaded with Sm2O3.

[0108] Step seven, the Sm2O3-loaded Ni / de-USY solid-liquid mixture obtained in step six is ​​placed at room temperature for static precipitation, the precipitated wet Sm2O3-loaded Ni / de-USY solid is placed in a vacuum drying oven at 110°C for 12 hours, and then placed in a muffle furnace for calcination at 500°C for 5 hours to obtain a finished Sm2O3-Ni / de-USY catalyst, i.e., a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst.

[0109] Example 7

[0110] A Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst comprises a USY molecular sieve carrier, a nickel compound supported on the USY carrier, and a samarium oxide. The mass percentage of USY zeolite in the supported ammonia decomposition catalyst is 98.85%, the mass percentage of the nickel compound is 1.3%, and the mass percentage of the samarium oxide is 0.22%.

[0111] The samarium oxide is Sm2O3, and the nickel compound is mainly NiO and NiAl2O4; among the nickel compounds, the mass percentage of NiO is 73%-84%, and the mass percentage of NiAl2O4 is 12%-25%.

[0112] The nickel compound also includes other nickel compounds, the mass percentage of the other nickel compounds is 0.1% to 5%, and the other nickel compounds are NiAlOOH and Ni3Al.

[0113] A method for preparing a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst comprises the following steps:

[0114] Step 1: Introduce quartz sand into the fixed bed catalyst bed to fix 5g USY molecular sieve, heat in a high-temperature tubular furnace, the tubular furnace carrier gas is nitrogen, the tubular furnace carrier gas flow rate is 100mL / min, the gas introduced into the water saturator is water vapor, the reaction temperature is 600°C, the reaction time is 1.5h, and obtain the pretreated USY molecular sieve;

[0115] Step 2: Dealumination reaction is performed on the pretreated USY molecular sieve obtained in step 1. The specific operation process is: mixing the pretreated USY molecular sieve with 0.9 mol / L benzoic acid to obtain a mixture; magnetically stirring the mixture in a constant temperature water bath at 90°C for 3 hours to obtain acid-treated USY; repeatedly filtering and washing the acid-treated USY with deionized water until a pH meter detects that the acid-treated USY is neutral to obtain a modified USY molecular sieve; placing the modified USY molecular sieve in a vacuum drying oven at 70°C and drying for 6 hours to obtain de-USY; the mixing ratio is 1 g of the pretreated USY molecular sieve and 6 mL of the benzoic acid solution.

[0116] Step 3, placing the de-USY in step 2 in a nickel nitrate solution with a molar concentration of 1.8 mol / L for ultrasonic-assisted equal volume impregnation, and then placing it in a magnetic stirrer for stirring, so that the nickel nitrate is loaded in the pores of the de-USY, to obtain a solid-liquid mixture of de-USY loaded with nickel nitrate;

[0117] Step 4: The nickel nitrate-loaded de-USY solid-liquid mixture obtained in step 3 is allowed to settle at room temperature, the wet nickel nitrate-loaded de-USY solid obtained by precipitation is placed in a vacuum drying oven for drying, and then placed in a muffle furnace at 500° C. for calcination for 5 hours to obtain nickel-modified de-USY;

[0118] Step 5: Place the nickel-modified de-USY obtained in step 4 into a high-temperature tube furnace, then heat the high-temperature tube furnace to 700°C, introduce hydrogen, and reduce the Ni(NO3)2 loaded in the de-USY pores to nickel compounds to form a Ni / de-USY catalyst; the gas flow rate is 100 mL / min, and the hydrogen introduction time is 2 h.

[0119] Step 6: Place the Ni / de-USY catalyst described in step 5 in a samarium nitrate solution with a molar concentration of 0.1 mol / L for ultrasonic-assisted equal volume impregnation to load samarium oxide in the pores of the Ni / de-USY, and then place it in a magnetic stirrer for stirring to obtain a Ni / de-USY solid-liquid mixture loaded with Sm2O3.

[0120] Step seven, the Sm2O3-loaded Ni / de-USY solid-liquid mixture obtained in step six is ​​placed at room temperature for static precipitation, the precipitated wet Sm2O3-loaded Ni / de-USY solid is placed in a vacuum drying oven at 110°C for 12 hours, and then placed in a muffle furnace for calcination at 500°C for 5 hours to obtain a finished Sm2O3-Ni / de-USY catalyst, i.e., a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst.

[0121] Example 8

[0122] A Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst comprises a USY molecular sieve carrier, a nickel compound supported on the USY carrier, and a samarium oxide. The mass percentage of USY zeolite in the supported ammonia decomposition catalyst is 98.46%, the mass percentage of the nickel compound is 1.2%, and the mass percentage of the samarium oxide is 0.34%.

[0123] The samarium oxide is Sm2O3, and the nickel compound is mainly NiO and NiAl2O4; among the nickel compounds, the mass percentage of NiO is 73%-84%, and the mass percentage of NiAl2O4 is 12%-25%.

[0124] The nickel compound also includes other nickel compounds, the mass percentage of the other nickel compounds is 0.1% to 5%, and the other nickel compounds are NiAlOOH and Ni3Al.

[0125] The present embodiment provides a method for preparing a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst, comprising the following steps:

[0126] Step 1: Introduce quartz sand into the fixed bed catalyst bed to fix 5g USY molecular sieve, heat in a high-temperature tubular furnace, the tubular furnace carrier gas is nitrogen, the tubular furnace carrier gas flow rate is 100mL / min, the gas introduced into the water saturator is water vapor, the reaction temperature is 600°C, the reaction time is 1.5h, and obtain the pretreated USY molecular sieve;

[0127] Step 2: Dealumination reaction is performed on the pretreated USY molecular sieve obtained in step 1. The specific operation process is: mixing the pretreated USY molecular sieve with 1 mol / L benzoic acid to obtain a mixture; magnetically stirring the mixture in a constant temperature water bath at 90°C for 3 hours to obtain acid-treated USY; repeatedly filtering and washing the acid-treated USY with deionized water until the pH meter detects that the acid-treated USY is neutral to obtain a modified USY molecular sieve; placing the modified USY molecular sieve in a vacuum drying oven at 70°C and drying for 6 hours to obtain de-USY; the mixing ratio is 1g of the pretreated USY molecular sieve and 8mL of the benzoic acid solution.

[0128] Step 3, placing the de-USY in step 2 in a nickel nitrate solution with a molar concentration of 1.8 mol / L for ultrasonic-assisted equal volume impregnation, and then placing it in a magnetic stirrer for stirring, so that the nickel nitrate is loaded in the pores of the de-USY, to obtain a solid-liquid mixture of de-USY loaded with nickel nitrate;

[0129] Step 4: The nickel nitrate-loaded de-USY solid-liquid mixture obtained in step 3 is allowed to settle at room temperature, the wet nickel nitrate-loaded de-USY solid obtained by precipitation is placed in a vacuum drying oven for drying, and then placed in a muffle furnace at 500° C. for calcination for 5 hours to obtain nickel-modified de-USY;

[0130] Step 5: Place the nickel-modified de-USY obtained in step 4 into a high-temperature tube furnace, then heat the high-temperature tube furnace to 700°C, introduce hydrogen, and reduce the Ni(NO3)2 loaded in the de-USY pores to nickel compounds to form a Ni / de-USY catalyst; the gas flow rate is 100 mL / min, and the hydrogen introduction time is 2 h.

[0131] Step 6: Place the Ni / de-USY catalyst described in step 5 in a samarium nitrate solution with a molar concentration of 0.1 mol / L for ultrasonic-assisted equal volume impregnation to load samarium oxide in the pores of the Ni / de-USY, and then place it in a magnetic stirrer for stirring to obtain a Ni / de-USY solid-liquid mixture loaded with Sm2O3.

[0132] Step seven, the Sm2O3-loaded Ni / de-USY solid-liquid mixture obtained in step six is ​​placed at room temperature for static precipitation, the precipitated wet Sm2O3-loaded Ni / de-USY solid is placed in a vacuum drying oven at 110°C for 12 hours, and then placed in a muffle furnace for calcination at 500°C for 5 hours to obtain a finished Sm2O3-Ni / de-USY catalyst, i.e., a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst.

[0133] Example 9

[0134] A Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst comprises a USY molecular sieve carrier, a nickel compound supported on the USY carrier, and a samarium oxide. The weight percentage of USY zeolite in the supported ammonia decomposition catalyst is 98.5%, the weight percentage of the nickel compound is 0.5%, and the weight percentage of the samarium oxide is 0.65%.

[0135] The samarium oxide is Sm2O3, and the nickel compound is mainly NiO and NiAl2O4; among the nickel compounds, the mass percentage of NiO is 73% to 84%, and the mass percentage of NiAl2O4 is 12% to 25%.

[0136] The nickel compound also includes other nickel compounds, the mass percentage of the other nickel compounds is 0.1% to 5%, and the other nickel compounds are NiAlOOH and Ni3Al.

[0137] The present embodiment provides a method for preparing a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst, comprising the following steps:

[0138] Step 1: Introduce quartz sand into the fixed bed catalyst bed to fix 5g USY molecular sieve, heat in a high-temperature tubular furnace, the tubular furnace carrier gas is nitrogen, the tubular furnace carrier gas flow rate is 100mL / min, the gas introduced into the water saturator is water vapor, the reaction temperature is 600°C, the reaction time is 3h, and a pretreated USY molecular sieve is obtained;

[0139] Step 2: Dealumination reaction is performed on the pretreated USY molecular sieve obtained in step 1. The specific operation process is: mixing the pretreated USY molecular sieve with 0.8 mol / L benzoic acid to obtain a mixture; magnetically stirring the mixture in a constant temperature water bath at 90°C for 3 hours to obtain acid-treated USY; repeatedly filtering and washing the acid-treated USY with deionized water until a pH meter detects that the acid-treated USY is neutral to obtain a modified USY molecular sieve; placing the modified USY molecular sieve in a vacuum drying oven at 70°C and drying for 6 hours to obtain de-USY; the mixing ratio is 1 g of the pretreated USY molecular sieve and 6 mL of the benzoic acid solution.

[0140] Step 3, placing the de-USY in step 2 in a nickel nitrate solution with a molar concentration of 1.7 mol / L for ultrasonic-assisted equal volume impregnation, and then placing it in a magnetic stirrer for stirring, so that the nickel nitrate is loaded in the pores of the de-USY, to obtain a solid-liquid mixture of de-USY loaded with nickel nitrate;

[0141] Step 4: The nickel nitrate-loaded de-USY solid-liquid mixture obtained in step 3 is allowed to settle at room temperature, the wet nickel nitrate-loaded de-USY solid obtained by precipitation is placed in a vacuum drying oven for drying, and then placed in a muffle furnace at 500° C. for calcination for 5 hours to obtain nickel-modified de-USY;

[0142] Step 5: Place the nickel-modified de-USY obtained in step 4 into a high-temperature tube furnace, heat the high-temperature tube furnace to 700°C, and introduce hydrogen to reduce the Ni(NO3)2 loaded in the de-USY pores to nickel compounds to form a Ni / de-USY catalyst; the gas flow rate is 100 mL / min, and the hydrogen introduction time is 2 h.

[0143] Step 6: Place the Ni / de-USY catalyst described in step 5 in a samarium nitrate solution with a molar concentration of 0.1 mol / L for ultrasonic-assisted equal volume impregnation to load samarium oxide in the pores of the Ni / de-USY, and then place it in a magnetic stirrer for stirring to obtain a Ni / de-USY solid-liquid mixture loaded with Sm2O3.

[0144] Step seven, the Sm2O3-loaded Ni / de-USY solid-liquid mixture obtained in step six is ​​placed at room temperature for static precipitation, the precipitated wet Sm2O3-loaded Ni / de-USY solid is placed in a vacuum drying oven at 110°C for 12 hours, and then placed in a muffle furnace for calcination at 500°C for 5 hours to obtain a finished Sm2O3-Ni / de-USY catalyst, i.e., a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst.

[0145] Next, Examples 1 to 9 are briefly described as follows:

[0146] First, in Examples 1-9, Figure 1 and Figure 2 The preparation process of a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst shown in the figure is used to prepare Sm2O3-Ni / de-USY.

[0147] Secondly, in Examples 1-9, de-USY was loaded with nickel, and then the de-USY molecular sieve was modified with Sm to obtain Sm2O3-Ni / de-USY. Figure 3 It can be seen that the Sm2O3-Ni / de-USY prepared by the present invention has obvious connected mesopores. The improvement of the connectivity between the pores is conducive to improving the accessibility of the active centers of the molecular sieve and greatly improving the diffusion and mass transfer performance of the active metals in the pores. Figure 4 It can be seen that the mesopores in the unmodified USY molecular sieve are mostly "inner hollow" type, the mesopores exist in isolation, and the connectivity between the pores is poor. Therefore, the present invention can effectively increase the active metal component of the catalyst after the catalyst is loaded with active metal.

[0148] Secondly, the preparation method of the Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst in Examples 1-9 is to hydrothermally pretreat the USY molecular sieve at 600°C and then treat it with benzoic acid to obtain de-USY. The dealuminated USY ammonia decomposition efficiency obtained by treating it with benzoic acid alone is obviously poor; Figure 5 As shown, the higher the temperature is, the higher the ammonia decomposition efficiency of the two catalysts is, and the efficiency of de-USY obtained by hydrothermal treatment followed by benzoic acid treatment is always greater than the efficiency of de-aluminum USY obtained by only benzoic acid treatment. It can be seen that the step of hydrothermal treatment followed by benzoic acid treatment adopted in the preparation method of the present invention can greatly improve the dealumination rate of USY, increase secondary pores, and increase the contact area between the reactant ammonia and the catalyst, thereby improving the ammonia decomposition efficiency of the catalyst.

[0149] Finally, the preparation methods of the Sm-doped modified Ni / de-USY ammonia hydrogen production catalysts in Examples 1-9 all adopt the ultrasound-assisted equal volume impregnation method, and the ammonia decomposition efficiency of the Sm2O3-Ni / de-USY prepared thereby is compared with that of the Sm2O3-Ni / de-USY prepared by the conventional impregnation method. Figure 6 As shown, the higher the temperature is, the higher the ammonia decomposition efficiency of the two catalysts is, and the efficiency of ammonia decomposition of Sm2O3-Ni / de-USY obtained by ultrasound-assisted equal volume impregnation method is always greater than the efficiency of ammonia decomposition of Sm2O3-Ni / de-USY obtained by conventional impregnation method. This shows that the use of ultrasound-assisted equal volume impregnation method can greatly increase the metal components on the surface and inside of the catalyst, and improve the ammonia decomposition efficiency of the catalyst.

[0150] In summary, the present invention adopts dealumination by hydrothermal pretreatment followed by acid treatment, which can effectively improve the dealumination efficiency of the molecular sieve, increase the secondary pores of the molecular sieve, increase the contact between ammonia and the active center of the molecular sieve, and improve the catalytic performance of the ammonia-to-hydrogen catalyst; the ammonia-to-hydrogen catalyst prepared by the method of ultrasonic-assisted equal-volume impregnation of loaded metals can improve the diffusion of nickel metal and samarium oxide in the active sites of the molecular sieve pores, and enhance the coordination interaction on the USY pore surface, thereby improving the ammonia decomposition efficiency of the ammonia-to-hydrogen catalyst.

[0151] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst, characterized in that: The Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst comprises a USY molecular sieve and a nickel compound and a samarium oxide supported on the USY molecular sieve; the mass percentage of the USY molecular sieve is 97.82% to 98.85%, the mass percentage of the nickel compound is 0.5% to 1.4%, and the mass percentage of the samarium oxide is 0.22% to 0.79%.

2. The Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst according to claim 1, characterized in that: The samarium oxide is Sm2O3, the nickel compounds are NiO, NiAl2O4 and other nickel compounds, among which the mass percentage of NiO is 73% to 84%, the mass percentage of NiAl2O4 is 12% to 25%, and the mass percentage of other nickel compounds is 0.1% to 5%, and the other nickel compounds are NiAlOOH and Ni3Al.

3. A method for preparing a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst as claimed in claim 1, comprising the following steps: Step 1: Perform high-temperature hydrothermal pretreatment on the USY molecular sieve. The specific operation process is: put the USY molecular sieve into a quartz tube, heat the high-temperature tube furnace, and then introduce an inert gas as a carrier gas into the quartz tube, and at the same time introduce gas into the quartz tube through a water saturator to obtain a pretreated USY molecular sieve; Step 2, the pretreated USY molecular sieve obtained in step 1 is subjected to dealumination reaction, and the specific operation process is: mixing the pretreated USY molecular sieve with an acid to obtain a mixture; stirring the mixture to obtain acid-treated USY; repeatedly filtering and washing the acid-treated USY with water until a pH meter detects that the acid-treated USY is neutral to obtain a modified USY molecular sieve; drying the modified USY molecular sieve to obtain de-USY; Step 3, placing the de-USY obtained in step 2 in a nickel nitrate solution for ultrasonic-assisted equal-volume impregnation to obtain impregnated de-USY, and then placing the impregnated de-USY in a magnetic stirrer for stirring to obtain a solid-liquid mixture of de-USY loaded with nickel nitrate; Step 4, allowing the nickel nitrate-loaded de-USY solid-liquid mixture obtained in step 3 to stand and precipitate at room temperature, placing the precipitated nickel nitrate-loaded de-USY in a vacuum drying oven to dry to obtain dry nickel nitrate-loaded de-USY, and then placing the dry nickel nitrate-loaded de-USY in a muffle furnace for calcination to obtain nickel-modified de-USY; Step 5, placing the nickel-modified de-USY obtained in step 4 into a high-temperature tube furnace, heating the high-temperature tube furnace, and then introducing a reducing gas into the high-temperature tube furnace to obtain a Ni / de-USY catalyst; Step 6: placing the Ni / de-USY catalyst obtained in step 5 in a Sm(NO3)3 solution for ultrasonic-assisted equal-volume impregnation, and then placing the impregnated Ni / de-USY catalyst in a magnetic stirrer for stirring to obtain a Ni / de-USY solid-liquid mixture loaded with Sm2O3; Step seven, the Sm2O3-loaded Ni / de-USY solid-liquid mixture obtained in step six is ​​placed at room temperature for static precipitation, the wet Sm2O3-loaded Ni / de-USY solid obtained by precipitation is placed in a vacuum drying oven for drying to obtain a dry product, and the dry product is then placed in a muffle furnace for roasting to obtain a finished Sm2O3-Ni / de-USY catalyst, i.e., a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst.

4. The method for preparing a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst according to claim 3, characterized in that: The temperature in step 1 is raised to 600° C.; the inert gas is nitrogen, the nitrogen flow rate is 100 mL / min, the gas introduced into the water saturator is water vapor, and the water vapor introduction time is 1.5 h to 3 h.

5. The method for preparing a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst according to claim 3, characterized in that: The acid in step 2 is benzoic acid, and the molar concentration of the benzoic acid is 0.8 mol / L to 1.0 mol / L; the mixing ratio of the pretreated USY molecular sieve and the acid is: 1 g of the pretreated USY molecular sieve and 5 ml to 10 mL of the benzoic acid solution, the stirring is magnetic stirring, the stirring condition is a constant temperature water bath at 90° C., and the stirring time is 3 hours; the water is deionized water; the drying is vacuum drying, the vacuum drying temperature is 70° C., and the drying time is 6 hours.

6. The method for preparing a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst according to claim 3, characterized in that: The molar concentration of the nickel nitrate solution in step 3 is 1.5 mol / L to 1.8 mol / L.

7. The method for preparing a Sm-doped modified Ni / de-USY ammonia-to-hydrogen catalyst according to claim 3, characterized in that: The calcination temperature in step 4 is 500° C. and the calcination time is 5 h.

8. According to the method for preparing a Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst as described in claim 3, the high-temperature tube furnace in step 5 is heated to 700° C., the reducing gas is hydrogen, the hydrogen introduction rate is 100 mL / min, and the introduction time is 2 h.

9. According to the method for preparing a Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst as described in claim 3, the molar concentration of the Sm(NO3)3 solution in step six is ​​0.1 mol / L.

10. According to the method for preparing a Sm-doped modified Ni / de-USY ammonia hydrogen production catalyst as described in claim 3, the drying temperature of the vacuum drying in step 7 is 110° C., and the drying time is 12 hours; the calcination temperature of the muffle furnace calcination is 500° C., and the calcination time is 5 hours.

Images