A method for preparing a catalyst for methanation of biomass straw gas and its application

Abstract

The present invention relates to the technical field of biomass raw material methanation, and specifically to a catalyst preparation method and application for biomass straw gas methanation. The catalyst preparation method for biomass straw gas methanation in the present invention has simple steps and is easy to operate; the catalyst is non-toxic and environmentally friendly, and will not cause secondary pollution; electron-hole pairs are generated under the action of light, and the recombination efficiency of electron-hole pairs is reduced by constructing a heterogeneous structure, and the oxidation capacity can be maintained for a long time; the catalyst prepared by the present invention can be used in the methanation process of straw, enhance the conversion efficiency of straw methanation, and then crack to improve the efficiency of hydrogen production.

Description

Technical Field

[0001] The invention relates to the technical field of methanation of biological raw materials, and in particular to a method for preparing a catalyst for methanation of biological straw fuel gas and application thereof. Background Art

[0002] Farmers in my country have a long history of using crop straw, but with the promotion of firewood-saving and coal-saving technologies, and the popularization of coal and liquefied gas, there is a large surplus of straw. my country is the world's largest agricultural producer, with abundant cellulose biomass resources, totaling more than 1.2 billion tons. Therefore, methanation of biomass straw gas can provide residents with more electricity and heat, especially by cracking methane to produce hydrogen. Hydrogen, as a clean energy source, does not cause environmental pollution and other advantages have attracted the attention of many researchers.

[0003] Therefore, using a new catalyst to increase the methane gas production in the methanation of biostraw gas and then increase the hydrogen production is the key issue that needs to be solved urgently. Summary of the invention

[0004] In order to solve the above problems, the first aspect of the present invention provides a method for preparing a biostraw gas methanation catalyst, which specifically comprises the following steps:

[0005] S1: adding a titanium oxide or aluminum oxide carrier and IVB, IIB and IVA main group metals or their oxides into deionized water, heating and stirring to obtain a solution A;

[0006] S2: Cooling the solution A and subjecting it to ultrasonic treatment to obtain solution B;

[0007] S3: adding VIIB, IB and VIII main group metals or their oxides to solution B while stirring to obtain solution C;

[0008] S4: heating and stirring solution C to obtain solution D;

[0009] S5: drying the solution D and then calcining it to obtain the catalyst.

[0010] Preferably, the heating and stirring time in S1 is 1-2 hours, and the heating temperature is 70-90°C; the heating and stirring time in S4 is 2-3 hours, and the heating temperature is 80-95°C.

[0011] Preferably, the titanium oxide or aluminum oxide carrier is at least one of nano titanium dioxide and nano aluminum oxide.

[0012] Preferably, the titanium oxide or aluminum oxide carrier is nano titanium dioxide.

[0013] The applicant creatively discovered that the calcination temperature in S5 has a great influence on the phase of titanium dioxide, which includes anatase, rutile and brookite titanium dioxide. When the calcination temperature exceeds 550°C, the titanium dioxide phase will be converted from anatase to rutile titanium dioxide. Although rutile titanium dioxide is more stable than anatase titanium dioxide, its catalytic activity is lower than that of anatase titanium dioxide. Because brookite is extremely unstable, it is not considered as a catalyst.

[0014] Preferably, the nano titanium dioxide has a particle size of 10-50 nm and a specific surface area of ​​50±20 m 2 / g.

[0015] As a preferred solution, the nano titanium dioxide is purchased from Chongqing Jingyi New Materials Co., Ltd., model number is P25.

[0016] As a preferred solution, the nano titanium dioxide has a particle size of 20-40 nm and a specific surface area of ​​50±15 m 2 / g.

[0017] Preferably, the IVB, IIB and IVA main group metal or its oxide is at least one of zinc, tin, zirconium or its oxide.

[0018] Preferably, the IVB, IIB and IVA main group metal or its oxide is zinc oxide, and the average particle size of the zinc oxide is 5-50 nm.

[0019] As a preferred solution, the zinc oxide is purchased from Darcy Nanotechnology (Changzhou) Co., Ltd., model number DXN-HQ20W.

[0020] As a preferred solution, the zinc oxide particle size is 10-30nm and the specific surface area is 20-45m 2 / g.

[0021] Preferably, the ultrasonic time in the S2 ultrasonic treatment is 30-60 min and the power is 300-900 W.

[0022] Preferably, the VIIB, IB and VIII main group metals or their oxides are at least one of iron, manganese, cobalt, copper or their oxides.

[0023] Preferably, the VIIB, IB and VIII main group metal or its oxide is cobalt oxide.

[0024] As a preferred solution, the cobalt oxide was purchased from Anhui Kerun Nanotechnology Co., Ltd., model KR-Co 3 O 4 -1.

[0025] As a preferred solution, the cobalt oxide has a particle size of 40-60 nm and a specific surface area of ​​20-45 m 2 / g.

[0026] Preferably, the calcination temperature in S5 is 400-550° C. and the calcination time is 2-5 h.

[0027] The applicant creatively discovered that when the calcination temperature in S5 is not between 400-550°C, there is insufficient contact between the titanium oxide or aluminum oxide carrier and the interface of the VIIB, IB and VIII main group or IVB, IIB and IVA main group metal or metal oxide, resulting in the inability of the electron-hole pairs generated during illumination to fully transfer between substances at the interface, thereby causing the recombination of electrons and holes and reducing the methanation conversion efficiency.

[0028] The second aspect of the present invention provides an application of a catalyst for methanation of biomass straw gas:

[0029] S1: Straw pretreatment: putting the biological straw into a grinder for grinding to obtain straw particles, and putting the straw particles into a photocatalytic reactor;

[0030] S2: mixing the catalyst and coal powder in a certain mass ratio and putting them into a reactor, introducing a certain mass of water vapor into the reactor, and reacting at 700-900° C. to obtain methane-rich gas;

[0031] S3: cracking the methane-rich gas to obtain hydrogen.

[0032] Preferably, the straw particles have a particle size of 200-500 μm.

[0033] Preferably, the coal powder has a particle size of 10-150 μm; the ash content of the coal powder is 2-8%; and the mesh size of the coal powder is 10-800 mesh.

[0034] As an optimized solution, the particle size of the coal powder is 20-50 μm; the ash content of the coal powder is 2-6%; and the mesh size of the coal powder is 100-500 mesh.

[0035] As an optimized solution, the coal powder is purchased from Lingshou County Huayao Mineral Products Processing Plant, model HY.

[0036] The mass ratio of the catalyst to coal powder is 1:(300-500).

[0037] The mass of the water vapor is 1.01-1.32 kg / (kg material·h).

[0038] Beneficial effects:

[0039] 1. The catalyst preparation method for methanation of biomass straw fuel gas in the present invention has simple steps and is easy to operate.

[0040] 2. The catalyst prepared by the catalyst preparation method for methanation of biomass straw fuel gas in the present invention is non-toxic and environmentally friendly and will not cause secondary pollution.

[0041] 3. The catalyst prepared by the catalyst preparation method for methanation of biomass straw fuel gas in the present invention generates electron-hole pairs under light irradiation, and the construction of a heterogeneous structure reduces the recombination efficiency of electron-hole pairs, and can maintain oxidation capacity for a long time.

[0042] 4. The catalyst prepared by the catalyst preparation method for biomass straw fuel gas methanation of the present invention is applied in the straw methanation process to enhance the conversion efficiency of the straw methanation.

[0043] 5. The catalyst prepared by the catalyst preparation method for methanation of biomass straw gas in the present invention is applied to the methanation process of straw. Methanation can be achieved only with sufficient humidity, temperature and light in the device, and the operation is simple and the steps are concise. DETAILED DESCRIPTION

[0044] Example 1

[0045] A method for preparing a catalyst for methanation of biomass straw gas, comprising the following steps:

[0046] S1: Add 50 mg zinc oxide and 100 mg titanium dioxide into 200 ml deionized water, heat and stir for 1.5 h at 80 °C to obtain solution A;

[0047] S2: subjecting the above solution A to ultrasonic treatment, with an ultrasonic time of 45 min and an ultrasonic power of 500 W to obtain solution B;

[0048] S3: Add 20 mg of cobalt oxide to the above solution B while stirring to obtain solution C;

[0049] S4: heating and stirring the above solution C for 1.5 h at 90° C. to obtain solution D;

[0050] S5: After drying the solution D, calcining it at a temperature of 450° C. for 3.5 h to obtain the catalyst.

[0051] The zinc oxide was purchased from Darcy Non Nanotechnology (Changzhou) Co., Ltd., model number DXN-HQ20W.

[0052] The zinc oxide particle size is 20nm and the specific surface area is 35m 2 / g.

[0053] The cobalt oxide was purchased from Anhui Kerun Nanotechnology Co., Ltd., model KR-Co 3 O 4 -1.

[0054] The cobalt oxide has a particle size of 50 nm and a specific surface area of ​​30 m 2 / g.

[0055] The nano titanium dioxide was purchased from Chongqing Jingyi New Materials Co., Ltd., model number P25.

[0056] The nano titanium dioxide has a particle size of 25 nm and a specific surface area of ​​50 m 2 / g.

[0057] A biomass straw gas methanogenization catalyst is used for straw methanogenization cracking to produce hydrogen.

[0058] S1: Straw pretreatment: The biological straw is put into a grinder for grinding to obtain straw particles with a particle size of 300 μm, and 100 g of the straw particles are put into a photocatalytic reactor;

[0059] S2: 30 mg of the catalyst and 12 g of coal powder are mixed and put into a photocatalytic reactor, 1.2 kg / (kg material·h) of water vapor is introduced into the reactor, and the reaction is carried out at 800° C. to obtain methane-rich gas;

[0060] S3: cracking the methane-rich gas to obtain hydrogen.

[0061] The particle size of the coal powder is 40 μm; the ash content of the coal powder is 4%; and the mesh number of the coal powder is 300 meshes.

[0062] The coal powder was purchased from Lingshou County Huayao Mineral Products Processing Plant, model number HY.

[0063] Example 2

[0064] A method for preparing a catalyst for methanation of biomass straw gas, comprising the following steps:

[0065] S1: Add 50 mg zinc oxide and 100 mg titanium dioxide into 200 ml deionized water, heat and stir for 2 h at 90 °C to obtain solution A;

[0066] S2: subjecting the above solution A to ultrasonic treatment, with an ultrasonic time of 60 min and an ultrasonic power of 900 W to obtain solution B;

[0067] S3: Add 20 mg of cobalt oxide to solution B while stirring to obtain solution C;

[0068] S4: Heat and stir solution C for 2 h at 95°C to obtain solution D;

[0069] S5: After drying the solution D, calcining it at a temperature of 550° C. for 5 h to obtain the catalyst.

[0070] The zinc oxide was purchased from Darcy Non Nanotechnology (Changzhou) Co., Ltd., model number DXN-HQ20W.

[0071] The zinc oxide particle size is 30nm and the specific surface area is 20m 2 / g.

[0072] The cobalt oxide was purchased from Anhui Kerun Nanotechnology Co., Ltd., model KR-Co 3 O 4 -1.

[0073] The cobalt oxide has a particle size of 60 nm and a specific surface area of ​​20 m 2 / g.

[0074] The nano titanium dioxide was purchased from Chongqing Jingyi New Materials Co., Ltd., model number P25.

[0075] The nano titanium dioxide has a particle size of 30 nm and a specific surface area of ​​65 m 2 / g.

[0076] A biomass straw gas methanogenization catalyst is used for straw methanogenization cracking to produce hydrogen.

[0077] S1: Straw pretreatment: The biological straw is put into a grinder for grinding to obtain straw particles with a particle size of 300 μm, and 100 g of the straw particles are put into a photocatalytic reactor;

[0078] S2: 30 mg of the catalyst and 15 g of coal powder are mixed and put into a photocatalytic reactor, 1.32 kg / (kg material·h) of water vapor is introduced into the reactor, and methane-rich gas is obtained by reaction at 900° C.;

[0079] S3: cracking the methane-rich gas to obtain hydrogen.

[0080] The particle size of the coal powder is 50 μm; the ash content of the coal powder is 6%; and the mesh number of the coal powder is 150 meshes.

[0081] The coal powder was purchased from Lingshou County Huayao Mineral Products Processing Plant, model number HY.

[0082] Example 3

[0083] A method for preparing a catalyst for methanation of biomass straw gas, comprising the following steps:

[0084] S1: Add 50 mg zinc oxide and 100 mg titanium dioxide into 200 ml deionized water, heat and stir for 1 h at 70 °C to obtain solution A;

[0085] S2: subjecting the above solution A to ultrasonic treatment, with an ultrasonic time of 30 min and an ultrasonic power of 500 W to obtain solution B;

[0086] S3: Add 20 mg of cobalt oxide to solution B while stirring to obtain solution C;

[0087] S4: Heat and stir solution C for 1 h at 80°C to obtain solution D;

[0088] S5: drying the solution D and then calcining it at a temperature of 400° C. for 2 h to obtain the catalyst.

[0089] The zinc oxide was purchased from Darcy Non Nanotechnology (Changzhou) Co., Ltd., model number DXN-HQ20W.

[0090] The zinc oxide particle size is 10 nm and the specific surface area is 45 m 2 / g.

[0091] The cobalt oxide was purchased from Anhui Kerun Nanotechnology Co., Ltd., model KR-Co 3 O 4 -1.

[0092] The cobalt oxide has a particle size of 40 nm and a specific surface area of ​​50 m 2 / g.

[0093] The nano titanium dioxide was purchased from Chongqing Jingyi New Materials Co., Ltd., model number P25.

[0094] The nano titanium dioxide has a particle size of 30 nm and a specific surface area of ​​50 m 2 / g.

[0095] A biomass straw gas methanogenization catalyst is used for straw methanogenization cracking to produce hydrogen.

[0096] S1: Straw pretreatment: The biological straw is put into a grinder for grinding to obtain straw particles with a particle size of 300 μm, and 100 g of the straw particles are put into a photocatalytic reactor;

[0097] S2: 30 mg of the catalyst and 9 g of coal powder are mixed and put into a photocatalytic reactor, 1.01 kg / (kg material·h) of water vapor is introduced into the reactor, and the reaction is carried out at 700° C. to obtain methane-rich gas;

[0098] S3: cracking the methane-rich gas to obtain hydrogen.

[0099] The particle size of the coal powder is 20 μm; the ash content of the coal powder is 2%; and the mesh number of the coal powder is 450 meshes.

[0100] The coal powder was purchased from Lingshou County Huayao Mineral Products Processing Plant, model number HY.

[0101] Example 4

[0102] Example 4 provides a method for preparing a catalyst for methanation of biomass straw gas. The preparation method is the same as that of Example 1, but the difference from Example 1 is that:

[0103] The cobalt oxide described in Example 4 is replaced by copper oxide.

[0104] The copper oxide was purchased from Beasley New Materials (Suzhou) Co., Ltd., model number ZD-CuO-2.

[0105] The copper oxide has a particle size of 50 nm and a specific surface area of ​​120 m 2 / g.

[0106] Example 4: The catalyst prepared by the preparation method of the present application is applied to straw methanogenesis and cracking to produce hydrogen, which is the same as Example 1.

[0107] Example 5

[0108] Example 5 provides a method for preparing a catalyst for methanation of biomass straw gas. The preparation method is the same as that of Example 1, but the difference from Example 1 is that:

[0109] The nano titanium dioxide described in Example 5 is replaced by nano aluminum oxide.

[0110] The nano aluminum oxide has a particle size of 20 nm and a specific surface area of ​​140 m 2 / g.

[0111] The nano-aluminum oxide was purchased from Nanjing Baoket New Materials Co., Ltd., model number PAT-G02R.

[0112] Example 5: The catalyst prepared by the preparation method of the present application is applied to straw methanogenesis and cracking to produce hydrogen, which is the same as Example 1.

[0113] Example 6

[0114] Example 6 provides a method for preparing a catalyst for methanation of biomass straw gas. The preparation method is the same as that of Example 1, but the difference from Example 1 is that:

[0115] The zinc oxide described in Example 6 is replaced by nickel oxide.

[0116] The nickel oxide was purchased from Shanghai Naio Nano Technology Co., Ltd., model number NO-O-007-1.

[0117] The particle size of the nickel oxide is 20 nm.

[0118] Example 6 The catalyst prepared by the preparation method of the present application is applied to straw methanogenesis and cracking to produce hydrogen, which is the same as Example 1.

[0119] Comparative Example 1

[0120] Comparative Example 1 provides a method for preparing a catalyst for methanation of biostraw gas, and the preparation method is the same as that of Example 1.

[0121] Example 5 The catalyst prepared by the preparation method of the present application is applied to straw methanogenic cracking to produce hydrogen, which is different from Example 1 in that:

[0122] The amount of water vapor introduced is 0.5 kg / (kg material·h).

[0123] Comparative Example 2

[0124] Comparative Example 2 provides a method for preparing a catalyst for methanation of biostraw gas, and the preparation method is the same as that of Example 1.

[0125] Comparative Example 2 The catalyst prepared by the preparation method of the present application is applied to straw methanogenic cracking to produce hydrogen, which is different from Example 1 in that:

[0126] The particle size of the coal powder is 2000 μm; the ash content of the coal powder is 15%; and the mesh number of the coal powder is 80 meshes.

[0127] Comparative Example 3

[0128] Comparative Example 3 provides a method for preparing a catalyst for methanation of biomass straw gas. The preparation method is the same as that of Example 1, but the difference from Example 1 is that:

[0129] The heating and stirring temperature in S1 is 50° C., and the heating and stirring time is 3 h.

[0130] Comparative Example 3: The catalyst prepared by the preparation method of the present application is applied to straw methanogenesis and cracking to produce hydrogen, which is the same as Example 1.

[0131] Comparative Example 4

[0132] Comparative Example 4 provides a method for preparing a catalyst for methanation of biomass straw gas, which is different from Example 1 in that:

[0133] The nano titanium dioxide in S1 is replaced by silicon dioxide.

[0134] The silicon dioxide was purchased from Shanghai Yuanjiang Chemical Co., Ltd., model number is YJ-0316.

[0135] The specific surface area of ​​the titanium dioxide is 240 m 2 / g.

[0136] Comparative Example 4: The catalyst prepared by the preparation method of the present application is applied to straw methanogenesis and cracking to produce hydrogen, which is the same as Example 1.

[0137] Comparative Example 5

[0138] Comparative Example 5 provides a method for preparing a catalyst for methanation of biomass straw gas, which is different from Example 1 in that:

[0139] The calcination temperature in S5 is 600°C.

[0140] Comparative Example 5: The catalyst prepared by the preparation method of the present application is applied to straw methanogenesis and cracking to produce hydrogen, which is the same as Example 1.

[0141] Comparative Example 6

[0142] Comparative Example 6 provides a method for preparing a catalyst for methanation of biomass straw gas, which is different from Example 1 in that:

[0143] No VIIB, IB or VIII main group metal or metal oxide is added to S1.

[0144] Comparative Example 6: The catalyst prepared by the preparation method of the present application is applied to straw methanogenesis and cracking to produce hydrogen, which is the same as Example 1.

[0145] Performance Testing

[0146] Methane-rich gas cracking experiment

[0147] The catalysts, coal powder and pretreated straw particles prepared in Examples 1-6 and Comparative Examples 1-6 were put into a photocatalytic reactor, water vapor was introduced, and straw methanation was carried out under sunlight conditions (500W xenon lamp was used for irradiation at night and on cloudy days), and then cracking was carried out to produce hydrogen. Fermentation was required for 24 hours in the early stage. The reactor could monitor the hydrogen production in real time. Hydrogen production was continued for 100 hours, and the maximum hydrogen production rate and hydrogen concentration were recorded. The data were recorded in Table 1.

[0148] Table 1

[0149] <![CDATA[Maximum hydrogen production rate (mL·h -1 )]]> Hydrogen concentration Example 1 78.3 53.2 Example 2 70.8 50.8 Example 3 69.4 49.7 Example 4 72.9 51.9 Example 5 65.7 45.3 Example 6 74.1 50.8 Comparative Example 1 31.5 30.6 Comparative Example 2 52.1 42.1 Comparative Example 3 42.5 37.8 Comparative Example 4 40.3 35.7 Comparative Example 5 38.9 28.6 Comparative Example 6 20.9 18.6

Claims

1. A method for preparing a biomass straw gas photocatalytic methanation catalyst, characterized in that: The specific steps include: S1: adding titanium oxide or aluminum oxide carrier and zinc oxide into deionized water, heating and stirring to obtain solution A; S2: cooling the solution A and then subjecting it to ultrasonic treatment to obtain solution B; S3: adding cobalt oxide or copper oxide to the above solution B while stirring to obtain solution C; S4: heating and stirring solution C to obtain solution D; S5: drying the solution D and then calcining it to obtain the catalyst; The titanium oxide or aluminum oxide carrier is at least one of titanium dioxide and aluminum oxide; The titanium dioxide particle size is 20-100nm and the specific surface area is 30-80m 2 / g; the aluminum oxide particle size is 5-70nm, and the specific surface area is 20-100m 2 / g; The heating and stirring time in S1 is 1-2h, and the heating temperature is 70-90°C; The calcination temperature in S5 is 400-550° C. and the calcination time is 2-5 hours.

2. The method for preparing the biomass straw gas photocatalytic methanation catalyst according to claim 1, characterized in that: The heating and stirring time in S4 is 2-3 hours, and the heating temperature is 80-95°C.

3. According to the method for preparing the biostraw gas photocatalytic methanation catalyst according to claim 1, the ultrasonic time in the S2 ultrasonic treatment is 30-60 min and the power is 300-900 W.

4. A catalyst prepared according to the method for preparing a biostraw gas photocatalytic methanation catalyst according to any one of claims 1 to 3.

5. The catalyst prepared by the method for preparing the biomass straw gas photocatalytic methanation catalyst according to claim 4 is applied in the field of straw methanation.