CN106669819A - AlPO4‑5 Molecular Sieve Supported Cu, Fe and MgO Catalyzed Method and Process for Hydrogen Production by Steam Reforming of Methanol - Google Patents

Abstract

The present invention uses AlPO ₄ ‑5 molecular sieve as carrier, Cu as active component, Fe and MgO as cocatalysts, adopts impregnation method to prepare Cu‑Fe‑MgO/AlPO ₄ ‑5 catalyst for hydrogen production by steam reforming of methanol. The mass fraction of Cu is 10%-20%, the mass fraction of Fe is 3%-10%, the mass fraction of MgO is 1%-3%, and the mass fraction of the carrier AlPO ₄ -5 molecular sieve is 67%-86%. The process conditions for producing hydrogen by steam reforming of methanol are: reaction temperature 240°C-320°C; reaction pressure is normal pressure; The mass space velocity is 1.8～7.2h ^‑1 . Under the optimal reaction conditions, the conversion rate of methanol can reach more than 90%, and the selectivity of hydrogen can reach more than 95%.

Description

AlPO4-5 Molecular Sieve Supported Cu, Fe and MgO Catalytic Method for Hydrogen Production by Steam Reforming of Methanol method and craft

technical field

The invention belongs to the technical field of chemical industry, and in particular relates to a preparation method and an application process of a catalyst that uses AlPO ₄ -5 molecular sieve as a carrier and supports Cu, Fe and MgO to catalyze methanol steam reforming to produce hydrogen.

Background technique

As an efficient and clean alternative energy, hydrogen energy is regarded as the most ideal clean energy in the 21st century. Hydrogen can be prepared in various ways, and steam reforming of methanol is an ideal method for small-scale hydrogen production. For the selection of catalysts, Cu-based catalysts are widely used due to their better activity, lower reaction temperature, and low price; in addition, Pd-based catalysts and bimetallic catalysts have better activity and stability. There are some reports _on catalysts for steam reforming _of methanol using Al ₂ O ₃ , _ATP , etc. as _carriers to support active components. Catalyst, the catalyst Cu-ZrO ₂ -CeO ₂ /Al ₂ O ₃ is prepared by impregnation method, the conversion rate of methanol and the selectivity of hydrogen are both above 95% (Chinese patent CN104857965A); ATP is also used as the carrier, and Cu is the active group The catalyst Cu-ZrO ₂ /ATP was prepared by impregnation method, and ZrO ₂ was used as co-catalyst, which also showed good activity. (Chinese patent CN104857965A); There is also a co-precipitation type palladium-zinc-based catalyst (Chinese patent CN102872867A) that is promoted by carbon nanotubes and scandium.

AlPO ₄ -5 is a microporous molecular sieve, which has the characteristics of large specific surface area, uniform pore size distribution, and adjustable surface acid strength. Moreover, AlPO ₄ -5 molecular sieve is used as a carrier to catalyze the hydrogen production reaction of methanol steam reforming, which has not been reported in the literature so far. The invention uses AlPO ₄ -5 molecular sieve as the catalyst carrier, and uses the impregnation method to support Cu, Fe and MgO to prepare the catalyst, which is used for the reaction of methanol and water vapor to produce hydrogen. The higher the CO, the lower the selectivity.

Contents of the invention

The present invention aims to provide a method for preparing a novel catalyst for methanol steam reforming hydrogen production with AlPO ₄ -5 molecular sieve as the carrier, Cu as the main active component, and Fe and MgO as co-catalysts. The prepared catalyst has high activity , good stability, long service life, can effectively improve the conversion rate of methanol and the selectivity of hydrogen, and reduce the content of carbon monoxide. When the catalyst is a combination of Cu, Fe and MgO catalysts, the mass fraction of Cu is 10% to 20%, the mass fraction of Fe is 3% to 10%, the mass fraction of MgO is 1% to 3%, and the carrier AlPO ₄ - The mass fraction of 5 molecular sieves is 67% to 86%.

In the catalyst, Cu is derived from metal salt Cu(NO ₃ ) ₂ ·3H ₂ O, Fe is derived from metal salt Fe(NO ₃ ) ₂ ·6H ₂ O, and MgO is derived from metal salt Mg(NO ₃ ) ₂ ·6H ₂ O.

The preparation method and the catalytic reaction process of the catalyst for hydrogen production by steam reforming of methanol are as follows:

1. Synthesis of carrier AlPO ₄ -5 molecular sieve:

Mix 18.09g of phosphoric acid and 40ml of distilled water evenly, add 11.765g of pseudoboehmite, stir for 1.5h, measure 15.268ml of triethylamine with a graduated cylinder, add it slowly, add 16.5ml of distilled water after the dropwise addition, and continue stirring for 1.5h , after the stirring is complete, measure its pH and record it, put it into a crystallization kettle, put it in an oven for crystallization at 180°C for 48 hours, take out the crystallization kettle, filter the solution, dry it, and roast it at 550°C to remove the template agent to obtain AlPO _4-5 molecular sieves.

2. Preparation of catalyst:

Prepare a nitrate aqueous solution containing Cu, Fe and Mg, impregnate AlPO ₄ -5 molecular sieve, stir evenly at room temperature, place it for 12 hours, put it in an oven for 12 hours at 110°C, and bake it at 550°C for 3 hours. It was reduced at ℃ for 2 hours, and then pressed to form a tablet after cooling down to room temperature, and the catalyst of 40-80 mesh was sieved for future use.

3. Catalytic reaction

Catalysts for hydrogen production by steam reforming of methanol The catalytic activity evaluation of steam reforming of methanol was carried out in a continuous flow fixed-bed reactor at atmospheric pressure. Before the reaction, place a certain amount of catalyst in the constant temperature section of the reactor, add an appropriate amount of quartz sand up and down, activate the catalyst with hydrogen at 300°C for 1.5 hours, then cool down to the temperature required for reaction, and start feeding after the temperature is stable, and the reaction The temperature range is 240°C to 320°C; the molar ratio of water and methanol in the feed is 1 to 1.4; the mass space velocity of the feed is 1.8 to 7.2h ^-1 . The product after the reaction is analyzed online with a gas chromatograph. The conversion rate of methanol is 36% to 90%, the selectivity of hydrogen is 95% to 99%, the selectivity of carbon monoxide is 0.1% to 3%, and the selectivity of carbon dioxide is 85%～99%, the selectivity of dimethyl ether is 0.9%～12%

detailed description

Example 1

Preparation of 1# catalyst (composition: Cu: 12%, Fe: 3%, MgO: 1%, AlPO ₄ -5: 84%).

Weigh 1.6294g Cu(NO ₃ ) ₂ ·3H ₂ O, 0.7750g Fe(NO ₃ ) ₂ ·6H ₂ O and 0.2272gMg(NO ₃ ) ₂ ·6H ₂ O, add 4ml of deionized water to dissolve, then add 3g of AlPO ₄ -5 was added to the completely dissolved nitrate aqueous solution, stirred evenly, and after standing at room temperature for 12 hours, it was moved into an oven and dried at 110°C for 12 hours, then it was roasted at 550°C for 3 hours in a tube furnace, and the temperature was lowered to 300°C Reduction by flowing hydrogen at ℃ for 2 hours, cooling to room temperature, pressing into tablets, and sieving 40-80 mesh particles to obtain 1# catalyst.

Example 2

Preparation of 2# catalyst (the composition is Cu: 15%, Fe: 5%, MgO: 1%, AlPO ₄ -5: 79%).

Weigh 2.1656g Cu(NO ₃ ) ₂ ·3H ₂ O, 1.3734g Fe(NO ₃ ) ₂ ·6H ₂ O and 0.2416gMg(NO ₃ ) ₂ ·6H ₂ O, add 4ml deionized water to dissolve, then add 3g AlPO ₄ -5 was added to the completely dissolved nitrate aqueous solution, stirred evenly, and after standing at room temperature for 12 hours, it was moved into an oven and dried at 110°C for 12 hours, then it was roasted at 550°C for 3 hours in a tube furnace, and the temperature was lowered to 300°C Reduction by flowing hydrogen at ℃ for 2 hours, cooling to room temperature, pressing into tablets, and sieving 40-80 mesh particles to obtain 2# catalyst.

Example 3

Preparation of 3# catalyst (composition: Cu: 15%, Fe: 7%, MgO: 1%, AlPO ₄ -5: 77%).

Weigh 2.2219g Cu(NO ₃ ) ₂ ·3H ₂ O, 1.9728g Fe(NO ₃ ) ₂ ·6H ₂ O and 0.2478gMg(NO ₃ ) ₂ ·6H ₂ O, add 4ml of deionized water to dissolve, then add 3g of AlPO ₄ -5 was added to the completely dissolved nitrate aqueous solution, stirred evenly, and after standing at room temperature for 12 hours, it was put into an oven and dried at 110°C for 12 hours, then it was roasted at 550°C for 3 hours in a tube furnace, and the temperature was lowered to Reduction by flowing hydrogen at 300°C for 2 hours, cooling to room temperature, pressing into tablets, and sieving 40-80 mesh particles to obtain 3# catalyst.

Example 4

Preparation of 4# catalyst (composition: Cu: 15%, Fe: 7%, MgO: 3%, AlPO ₄ -5: 75%).

Weigh 2.2812g Cu(NO ₃ ) ₂ ·3H ₂ O, 2.0254g Fe(NO ₃ ) ₂ ·6H ₂ O and 0.7635gMg(NO ₃ ) ₂ ·6H ₂ O, add 4ml of deionized water to dissolve, then add 3g of AlPO ₄ -5 was added to the completely dissolved nitrate aqueous solution, stirred evenly, and after standing at room temperature for 12 hours, it was put into an oven and dried at 110°C for 12 hours, then it was roasted at 550°C for 3 hours in a tube furnace, and the temperature was lowered to Reduction by flowing hydrogen at 300°C for 2 hours, cooling to room temperature, pressing into tablets, and sieving 40-80 mesh particles to obtain 4# catalyst.

Example 5

Preparation of 5# catalyst (the composition is Cu: 17%, Fe: 5%, MgO: 2%, AlPO ₄ -5: 76%).

Weigh 2.5513g Cu(NO ₃ ) ₂ ·3H ₂ O, 1.4276g Fe(NO ₃ ) ₂ ·6H ₂ O and 0.5022gMg(NO ₃ ) ₂ ·6H ₂ O, add 4ml deionized water to dissolve, then add 3g AlPO ₄ -5 was added to the completely dissolved nitrate aqueous solution, and after standing at room temperature for 12 hours, it was moved into an oven and dried at 110°C for 12 hours, then it was roasted at 550°C for 3 hours in a tube furnace, and cooled to 300°C for 3 hours. Reduction with hydrogen for 2 hours, cooling to room temperature, pressing into tablets, and sieving out 40-80 mesh particles to obtain 5# catalyst.

Example 6

The catalyst activity was investigated in a continuous-flow atmospheric fixed-bed reactor. Weigh 0.5g of 1# (or 2#~5#) catalyst and place it in the constant temperature section of the reaction tube, add an appropriate amount of quartz sand to the upper and lower parts of the reaction tube, pass hydrogen (30mL·min ^-1 ) to activate and reduce at 300°C for 1.5h; To 300°C, feed the gasified raw materials (methanol and water), the water-alcohol molar ratio is 1.1:1, the mass space velocity of the feed is 3.6h ^-1 , and the product is analyzed online by gas chromatography. See Table 1 for the evaluation results of catalysts 1# to 5#.

Table 1 Catalytic activity of 1~5# catalysts for hydrogen production by steam reforming of methanol at 300°C

Example 7

The catalyst activity was investigated in a continuous flow atmospheric fixed bed reactor. Weigh 0.5g of 2# catalyst and place it in the constant temperature section of the reaction tube, add an appropriate amount of quartz sand to the upper and lower parts of the reaction tube, and pass hydrogen (30mL·min ^-1 ) to activate and reduce at 300°C for 1.5h; the temperature range of the investigation is 240°C to 300°C , feed the gasified raw materials (methanol and water), the water-alcohol molar ratio is 1.1:1, the mass space velocity of the feed is 3.6h ^-1 , and the product is analyzed online by gas chromatography. See Table 2 for the evaluation results.

Table 2 Catalytic activity of catalyst 2# for hydrogen production by steam reforming of methanol at different temperatures

Example 8

Weigh 0.5g of 2# catalyst and place it in the constant temperature section of the reaction tube, pass hydrogen gas (30mL·min ^-1 ) to activate at 300°C for 1.5h; water), the water-alcohol molar ratio is 1-1.4, the mass space velocity of the feed is 3.6h ^-1 , the product is analyzed online by gas chromatography, and the evaluation results are shown in Table 3.

Table 3 Catalytic activity of catalyst 2# for hydrogen production by steam reforming of methanol at different water-alcohol ratios

Claims (4)

1. A methanol steam reforming hydrogen production catalyst with AlPO ₄ -5 molecular sieve as the carrier, its basic characteristics are: AlPO ₄ -5 molecular sieve is the catalyst carrier, and the supporting components are Cu, Fe and MgO. 2. according to the catalyzer that steam reforming of methanol prepares hydrogen described in claim 1, it is characterized in that: the massfraction of Cu is 10%～20%, the massfraction of Fe is 3%～10%, the massfraction of MgO is 1 % to 3%, and the mass fraction of the carrier AlPO ₄ -5 molecular sieve is 67% to 86%. 3. the preparation method of the catalyzer that steam reforming of methanol prepares hydrogen described in claim 1 is characterized in that: adopt impregnation method to prepare catalyzer, step is as follows: (1) take _AlPO4-5 molecular sieve as carrier; (2) prepare The nitrate aqueous solution containing Cu, Fe and Mg is impregnated with AlPO ₄ -5 molecular sieves, placed at room temperature for 12 hours, then placed in an oven to dry at 110°C for 12 hours, roasted in a tube furnace at 550°C for 3 hours, cooled, and then injected with hydrogen at 300°C ℃ reduction for 2 hours, after cooling down to room temperature, tablet molding is carried out, and the catalyst of 40-80 mesh is sieved for use. 4. The application process of preparing hydrogen catalyst by methanol steam reforming according to claim 1: adopt continuous flow type normal pressure fixed bed reactor, place a certain amount of catalyst in the constant temperature section before the reaction, add quartz sand up and down, first at 300 After activation with _H2 at ℃ for 1.5h, adjust to the required reaction temperature, the reaction temperature is 240℃～320℃; the molar ratio of feed water to methanol in the reactor is 1～1.4; the mass space velocity of raw material liquid feed is 1.8 ~7.2h ^-1 .