CN111097536A

CN111097536A - Methanation catalyst and preparation method thereof

Info

Publication number: CN111097536A
Application number: CN201811255468.XA
Authority: CN
Inventors: 徐洋; 鲁树亮; 陈勇; 郝雪松; 吴佳佳
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Priority date: 2018-10-26
Filing date: 2018-10-26
Publication date: 2020-05-05

Abstract

The invention relates to a methanation catalyst and a preparation method thereof in the field of catalysts. The methanation catalyst comprises the following components in percentage by total weight: 3-63 wt% of active component; 37-97 wt% of a carrier; the active component is at least one of Ni, Fe and Co. The methanation catalyst can be obtained by loading components including soluble salts corresponding to active components on a modified carrier by adopting an impregnation method and drying and roasting the modified carrier. The catalyst provided by the invention has good activity, the active component has better dispersity, and the catalyst can be used for methanation reaction.

Description

Methanation catalyst and preparation method thereof

Technical Field

The invention relates to the field of catalysts, and in particular relates to a methanation catalyst and a preparation method thereof.

Background

With the increasing shortage of petroleum resources, the Fischer-Tropsch synthesis-based coal conversion technology attracts great attention from the energy source and academic circles. Methanation is the simplest reaction in Fischer-Tropsch synthesis, is mainly applied to the fields of ethylene industry, ammonia synthesis, hydrogen purification and coal gasification, and aims to convert COx into methane or remove impurity COx in raw material gas so as to achieve the purpose of purification. Wherein the natural gas is one of fossil energy, and is mainly applied to the fields of chemical industry and fuel, and the main component of the natural gas can be synthesis gas (COx, H)₂) Obtained by catalytic conversion. As the simplest Fischer-Tropsch synthesis reaction, methanation has the advantages of high heat value, high conversion rate, single product, good economic benefit and the like.

The reaction equation for methanation is as follows:

CO+3H₂→CH₄+H₂OΔH₀＝-206KJ/mol

CO₂+4H₂→CH₄+2H₂OΔH₀＝-165KJ/mol

the methanation catalysts on the market are very wide in variety, and the composition of the methanation catalysts is basically composed of a carrier and an active component. The carrier is used as the important component of the catalyst, is a dispersant, an adhesive or a support of the main catalyst, and is a framework for loading the main catalyst. The function of the support is mainly to provide an effective surface and a suitable pore structure, to enhance the mechanical strength of the catalyst, to provide the catalyst with a certain ability to adapt to external changes, to improve the thermal conductivity of the catalyst and to provide additional active sites, etc. The macrostructure of the catalyst, such as specific surface, pore structure, porosity and pore size distribution, has a great influence on the activity and selectivity of the catalyst, and the macrostructure is often determined by the carrier. In order to meet the requirement of industrial strong exothermic/endothermic reaction, the carrier generally has large heat capacity and good thermal conductivity, so that the reaction heat can be rapidly transferred out/in, the sintering and inactivation of the catalyst or the equipment damage caused by local overheating can be avoided, and the side reaction at high temperature can be avoided, thereby improving the selectivity of the catalyst.

For the methanation reaction of CO, the active components with high catalytic activity are Ru, Ni, Fe, Co, Pd, Pt and the like. The Fe-based catalyst is a better choice for industrial catalyst design due to low price and rich sources of raw materials. The tolerance of the Co-based catalyst to harsh environments is relatively strong. The CO methanation catalyst with industrial application prospect is mainly a Ru-based catalyst and a Ni-based catalyst, the Ru-based catalyst has higher activity than the Ni-based catalyst and becomes a research hotspot once, but Ru is used as a noble metal and is expensive, and an Ru (CO) x complex formed by Ru and CO is easy to sublimate to cause loss of active components. Therefore, in recent years, Ni-based catalysts have been developed as CO methanation catalysts. The methanation reaction on the Ni-based catalyst has higher activity, good selectivity, low price and easy obtainment, and is the catalyst with the most industrial application prospect, and domestic methanation catalysts are mainly J series, such as J103, J104, J105 and the like. The catalysts mainly use Ni as an active component, and belong to a nickel active component, wherein the content of nickel is generally between 10 and 40wt percent.

High molecules generally refer to compounds having a relatively high molecular weight of several thousands to several millions, and are widely used in sophisticated technologies, industrial applications, and residential lives due to their outstanding properties. The polymer is very rich in types, wherein the water-soluble polymer is a polymer material with strong hydrophilicity and can be dissolved or swelled in water to form an aqueous solution or a dispersion system. The water-soluble polymer can be classified into cationic, anionic and nonionic water-soluble polymers according to hydrophilic groups, cationic groups such as tertiary amine groups and quaternary amine groups, anionic groups such as carboxylic acid groups, sulfonic acid groups, phosphoric acid groups and sulfuric acid groups, and polar nonionic groups such as hydroxyl groups, ether groups, amine groups and amide groups. The natural water-soluble polymer is extracted by physical or physical-chemical methods with plants or animals as raw materials, mainly comprising starch, seaweed, vegetable gum, animal gum and the like, the semisynthetic water-soluble polymer is obtained by chemically modifying natural substances with modified cellulose and modified starch, and the synthetic water-soluble polymer comprises two categories of polymerization and condensation.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a methanation catalyst. In particular to a methanation catalyst and a preparation method thereof.

One of the purposes of the invention is to provide a methanation catalyst which comprises the following components in percentage by weight:

3-63 wt% of active component; preferably 8-58 wt%;

37-97 wt% of a carrier; preferably 42 to 92 wt%.

More preferably, the following components may be included in percentages:

28-55 wt% of active component;

45-72 wt% of a carrier.

Wherein,

the active component can be at least one selected from Ni, Fe and Co.

The carrier can be at least one of alumina, zirconia, rare earth oxide, magnesia, barium oxide, hydrotalcite, cement, spinel, periclase, titanium dioxide, kaolin, kieselguhr, silicon dioxide and composite metal oxide.

Wherein the composite metal oxide is selected from Al₂O₃-SiO₂、Al₂O₃-MgO、Al₂O₃-TiO₂、Al₂O₃-ZrO₂、SiO₂-MgO、SiO₂-TiO₂、SiO₂-ZrO₂、MgO-TiO₂、MgO-ZrO₂、TiO₂-ZrO₂、Al₂O₃-SiO₂-MgO、Al₂O₃-SiO₂-TiO₂、Al₂O₃-SiO₂-ZrO₂、SiO₂-MgO-TiO₂、SiO₂-MgO-ZrO₂、MgO-TiO₂-ZrO₂、Al₂O₃-SiO₂-MgO-TiO₂、Al₂O₃-SiO₂-MgO-ZrO₂、SiO₂-MgO-TiO₂-ZrO₂、Al₂O₃-SiO₂-MgO-TiO₂-ZrO₂At least one of (1).

The methanation catalyst is characterized in that components including soluble salts corresponding to active components are soaked on a carrier modified by water-soluble polymers, and the finished product methanation catalyst can be prepared after drying and roasting.

The other purpose of the invention is to provide a preparation method of the methanation catalyst, which can be obtained by loading a component containing soluble salt corresponding to the active component on a carrier modified by a water-soluble polymer by an impregnation method, and drying and roasting the carrier.

Specifically, the preparation method may include the steps of:

preparing soluble salt corresponding to the active component into solution A according to the using amount; preparing a water-soluble polymer into a solution B;

the method comprises the following steps: uniformly stirring the solution B, then soaking the solution B on a carrier, and drying and roasting the solution B to obtain a water-soluble polymer modified carrier;

step two: and uniformly stirring the solution A, soaking the solution A on a carrier modified by a water-soluble polymer, and drying and roasting to obtain the methanation catalyst.

Wherein,

the solvent for preparing the solution A, B is water, preferably deionized water; dissolving according to the maximum solubility, wherein the dosage of the solvent is enough to completely dissolve the soluble salt and the water-soluble polymer corresponding to the active component.

In the specific operation, the weight usage amount of the solvent in the solution a and the soluble salt corresponding to the active component can be 1: (1-4), can be adjusted according to actual conditions, and can be fully dissolved.

The soluble salt corresponding to the active component can be selected from water soluble salts commonly used in the field, and can be selected from nitrate, carbonate and the like, and nitrate is preferred.

The impregnation method can be an equal volume impregnation method, and specifically, the solution A, B can be added to the carrier.

The dosage of the water-soluble polymer can be 0.1-10 wt% of the total weight of the active component and the carrier in the catalyst finished product obtained after reduction.

The water-soluble polymer can be at least one selected from polyvinyl alcohol, polyacrylamide, polyacrylic acid, polyoxyethylene, polyethylene glycol (molecular weight is 200-20000), polymaleic anhydride, polyvinylpyrrolidone and carboxymethyl cellulose.

The drying temperature in the first step can be 60-140 ℃, and the drying time can be 1-10 h;

the roasting temperature in the first step can be 250-650 ℃, and the roasting time can be 1-10 h.

The drying temperature in the second step can be 60-140 ℃, and the drying time can be 1-10 h;

the roasting temperature in the second step can be 250-650 ℃, and the roasting time can be 1-10 h.

Dissolving water-soluble polymer in water, impregnating and loading the water-soluble polymer on a carrier, so that part of acid centers on the surface of the carrier and in a pore channel are firstly combined with the water-soluble polymer, drying the water-soluble polymer, then tightly combining the polymer with the acid centers of the carrier, changing the property of the carrier, then dissolving an active component in the water, impregnating the modified carrier, combining the rest acid centers on the surface of the carrier and in the pore channel with the active component, drying and roasting the active component to obtain the finished catalyst. The acid centers of the carrier treated by the macromolecules are changed, part of the acid centers are occupied by the macromolecules, the macromolecules play a spacing role on the active components, the active components are prevented from being gathered and accumulated, and then the active centers are covered, after the drying roasting, the macromolecules spaced at the active components are completely decomposed into gas after the roasting, and only the active components are remained on the surface of the carrier, so that the dispersion degree of the active components of the catalyst can be improved, and the activity of the catalyst is increased.

The catalyst has good activity, the active components have better dispersity, and the catalyst is suitable for methanation reaction in the ethylene industry and methanation reaction in the coal gasification or fertilizer industry field, preferably methanation reaction in the ethylene industry.

Detailed Description

The present invention will be further described with reference to the following examples. However, the present invention is not limited to these examples.

In the examples of the application, the raw materials are all commercially available.

Example 1

1g of polyvinyl alcohol is dissolved in deionized water and stirred uniformly, and the carrier of 10g of zirconium oxide (ZrO) is impregnated by an isometric impregnation method₂) Putting the impregnated product into an oven at 80 ℃, drying for 10h, putting the dried catalyst into a muffle furnace, and roasting at 300 ℃ for 4h to obtain the modified zirconium oxide (ZrO)₂) 15g of nickel nitrate (Ni (NO) was added₃)₂.6H₂O) is dissolved in deionized water, is evenly stirred and is soaked in the modified zirconium oxide (ZrO) by an isometric soaking method₂) And placing the impregnated product into a drying oven at 100 ℃, drying for 2h, and placing the dried product into a muffle furnace to roast for 10h at 300 ℃ to obtain a catalyst product.

Example 2

0.5g of polyethylene glycol 20000 is dissolved in deionized water and stirred uniformly, and the carrier 10g of silicon oxide (SiO) is impregnated by an equal volume impregnation method₂) Putting the impregnated product into a drying oven at 100 ℃, drying for 5h, putting the dried catalyst into a muffle furnace, and roasting at 250 ℃ for 10h to obtain modified silicon oxide (SiO)₂) 5g of iron nitrate (Fe (NO)₃)₃) Dissolving in deionized water, stirring, and soaking in modified silicon oxide (SiO) by isovolumetric soaking method₂) Placing the impregnated product into a 120 ℃ oven, drying for 6h, placing the dried product into a muffle furnace, and roasting at 600 ℃ for 1hAnd obtaining the catalyst product.

Example 3

0.6g of carboxymethyl cellulose is dissolved in deionized water and stirred uniformly, and the load of 10g of alumina (Al) is impregnated by an isometric impregnation method₂O₃) Putting the impregnated product into an oven at 140 ℃, drying for 1h, putting the dried catalyst into a muffle furnace, and roasting at 650 ℃ for 1h to obtain modified alumina (Al)₂O₃) 25g of cobalt nitrate (Co (NO) was added₃)₂.6H₂Dissolving O) in deionized water, stirring, soaking in modified aluminum oxide (Al) by isovolumetric immersion method₂O₃) And placing the impregnated product into an oven at 80 ℃, drying for 7h, and placing the dried product into a muffle furnace to roast for 3h at 500 ℃ to obtain a catalyst product.

Example 4

Dissolving 1.5g of polyvinyl alcohol in deionized water, stirring uniformly, and impregnating a carrier of 10g of titanium oxide (TiO) by using an isometric impregnation method₂) Putting the impregnated product into a 120 ℃ oven, drying for 4h, putting the dried catalyst into a muffle furnace, and roasting at 400 ℃ for 4h to obtain modified titanium oxide (TiO)₂) 30g of nickel nitrate (Ni (NO) was added₃)₂.6H₂O) is dissolved in deionized water, evenly stirred and dipped in the modified titanium oxide (TiO) by an isometric dipping method₂) And placing the impregnated product into a drying oven at 90 ℃, drying for 8h, and placing the dried product into a muffle furnace to roast for 4h at 400 ℃ to obtain a catalyst product.

Example 5

0.8g of polyacrylic acid is dissolved in deionized water and stirred uniformly, and the carrier of 10g of alumina-zirconia (Al) is impregnated by an isovolumetric impregnation method₂O₃-ZrO₂) Putting the impregnated product into an oven at 130 ℃, drying for 1h, putting the dried catalyst into a muffle furnace, and roasting at 450 ℃ for 3h to obtain modified alumina-zirconia (Al)₂O₃-ZrO₂) 45g of iron nitrate (Fe (NO)₃)₃) Dissolving in deionized water, stirring, and soaking in modified alumina-zirconia (Al) by isovolumetric immersion method₂O₃-ZrO₂) And placing the impregnated product into an oven at 80 ℃, drying for 8h, and placing the dried product into a muffle furnace to roast for 9h at 250 ℃ to obtain a catalyst product.

Example 6

Dissolving 1g of polyacrylamide in deionized water, stirring uniformly, impregnating and loading on 10g of barium oxide (BaO) by using an isometric impregnation method, placing the impregnated product in an oven at 140 ℃, drying for 5h, placing the dried catalyst in a muffle furnace, roasting for 8h at 500 ℃ to obtain modified barium oxide (BaO), and adding 20g of cobalt nitrate (Co (NO)₃)₂.6H₂And O) dissolving in deionized water, uniformly stirring, soaking in modified barium oxide (BaO) by using an isometric soaking method, placing the soaked product in a drying oven at 100 ℃, drying for 5h, placing the dried product in a muffle furnace, and roasting at 300 ℃ for 6h to obtain the catalyst product.

Example 7

0.4g of polyvinylpyrrolidone is dissolved in deionized water and stirred uniformly, and the carrier of 10g of alumina-titanium oxide (Al) is impregnated by an isometric impregnation method₂O₃-TiO₂) Putting the impregnated product into a baking oven at 140 ℃, drying for 2h, putting the dried catalyst into a muffle furnace, and roasting at 500 ℃ for 6h to obtain modified alumina-titanium oxide (Al)₂O₃-TiO₂) 40g of nickel nitrate (Ni (NO))₃)₂.6H₂Dissolving O) in deionized water, stirring, soaking in modified alumina-titanium oxide (Al) by isovolumetric immersion method₂O₃-TiO₂) And placing the impregnated product into a drying oven at 100 ℃, drying for 5h, and placing the dried product into a muffle furnace to roast for 3h at 500 ℃ to obtain a catalyst product.

Comparative example 1

15g of nickel nitrate (Ni (NO))₃)₂.6H₂O) is dissolved in deionized water and evenly stirred, the solution is evenly stirred and dipped and loaded in 10g of zirconium oxide (ZrO) after being mixed₂) Putting the impregnated product into a drying oven at 100 ℃, drying for 2h, putting the dried product into a muffle furnace, and roasting at 300 ℃ for 10h to obtain a catalyst product。

Comparative example 2

5g of iron nitrate (Fe (NO)₃)₃) Dissolving in deionized water, stirring, mixing the above solutions, stirring, soaking and loading 10g of silicon oxide (SiO)₂) And (3) placing the impregnated product into a 120 ℃ oven, drying for 6h, and placing the dried product into a muffle furnace to roast for 1h at 600 ℃ to obtain a catalyst product.

And (3) testing the methanation reaction performance:

measuring 5mL of catalyst, loading the catalyst into a stainless steel fixed bed reactor, and introducing high-purity N₂Heating to 120 ℃ at a flow rate of 300mL/min to obtain high-purity N₂Switch to H₂The flow rate is 200mL/min, the temperature is raised to 400-450 ℃ and kept for 4H, and then H is added₂Switching to raw material gas, cutting in the raw material gas at different reaction temperatures of 150-250 ℃, wherein the reaction pressure is 3.0MPa, and the gas composition after reaction is analyzed by Agilent 7890 gas chromatography. (raw material gas composition: CO 0.5%; CO₂0.05％；H₂99.45％)

The catalysts prepared in examples 1 to 7 and comparative examples 1 to 2 were subjected to reaction evaluation according to the above evaluation methods, and the detailed evaluation results are shown in table 1.

TABLE 1 evaluation results of COx methanation reaction of catalyst (at a temperature of 200 ℃ in the reaction bed)

As can be seen from the results in Table 1, the catalysts of the examples of the present invention have higher COx conversion rate of methanation reaction than the comparative examples under the same conditions, which indicates that the catalysts have high activity; the catalysts in the examples have a higher degree of dispersion.

Claims

1. A methanation catalyst comprises the following components in percentage by weight:

3-63 wt% of active component;

37-97 wt% of a carrier;

the active component is at least one of Ni, Fe and Co.

2. Methanation catalyst according to claim 1, characterized in that it comprises, in percentages by total weight:

8-58 wt% of active component;

42-92 wt% of a carrier.

3. Methanation catalyst according to claim 1 or 2, characterized in that:

the carrier is at least one of alumina, zirconia, rare earth oxide, magnesia, barium oxide, hydrotalcite, cement, spinel, periclase, titanium dioxide, kaolin, kieselguhr, silicon dioxide and composite metal oxide;

the composite metal oxide is selected from Al₂O₃-SiO₂、Al₂O₃-MgO、Al₂O₃-TiO₂、Al₂O₃-ZrO₂、SiO₂-MgO、SiO₂-TiO₂、SiO₂-ZrO₂、MgO-TiO₂、MgO-ZrO₂、TiO₂-ZrO₂、Al₂O₃-SiO₂-MgO、Al₂O₃-SiO₂-TiO₂、Al₂O₃-SiO₂-ZrO₂、SiO₂-MgO-TiO₂、SiO₂-MgO-ZrO₂、MgO-TiO₂-ZrO₂、Al₂O₃-SiO₂-MgO-TiO₂、Al₂O₃-SiO₂-MgO-ZrO₂、SiO₂-MgO-TiO₂-ZrO₂、Al₂O₃-SiO₂-MgO-TiO₂-ZrO₂At least one of (1).

4. The methanation catalyst according to any one of claims 1 to 3, characterized in that a component containing a soluble salt corresponding to the active component is supported on a carrier modified with a water-soluble polymer by an impregnation method, and the catalyst is obtained by drying and calcining.

5. The preparation method of the methanation catalyst according to any one of claims 1 to 4, characterized by comprising the steps of:

preparing soluble salt corresponding to the active component into solution A; preparing a water-soluble polymer into a solution B;

the method comprises the following steps: uniformly stirring the solution B, then soaking the solution B on a carrier, and drying and roasting the solution B to obtain a modified carrier;

step two: and uniformly stirring the solution A, soaking the solution A on the modified carrier, and drying and roasting to obtain the methanation catalyst.

6. The preparation method of a methanation catalyst according to claim 5, characterized in that:

the dosage of the water-soluble polymer is 0.1-10 wt% of the total weight of the active component and the carrier.

7. The preparation method of a methanation catalyst according to claim 5, characterized in that:

the water-soluble polymer is at least one selected from polyvinyl alcohol, polyacrylamide, polyacrylic acid, polyoxyethylene, polyethylene glycol, polymaleic anhydride, polyvinylpyrrolidone and carboxymethyl cellulose.

8. The preparation method of a methanation catalyst according to claim 5, characterized in that:

the drying temperature in the first step is 60-140 ℃, and the drying time is 1-10 h;

the roasting temperature in the first step is 250-650 ℃, and the roasting time is 1-10 h.

9. The preparation method of a methanation catalyst according to claim 5, characterized in that:

the drying temperature in the second step is 60-140 ℃, and the drying time is 1-10 h;

and the roasting temperature in the second step is 250-650 ℃, and the roasting time is 1-10 h.

10. A methanation catalyst prepared by the preparation method according to any one of claims 5 to 9.