阅读说明：本技术 一种高稳定性生物乙醇制乙烯催化剂及制备和应用 (High-stability catalyst for preparing ethylene from bioethanol, and preparation and application thereof ) 是由 王峰 李书双 于 2018-09-13 设计创作，主要内容包括：本发明涉及一种具有高稳定性生物乙醇脱水制乙烯催化剂及其制备方法和应用。它是在含硅介孔分子筛的制备过程中原位引入制备含硅杂多酸(盐)的原料,使含硅杂多酸(盐)与含硅介孔分子筛材料原位同步生成,由于二者原料均含有硅酸根组份,通过硅氧四面体的连接,所生成的含硅杂多酸(盐)会被“锚定”在含硅介孔分子筛材料骨架中。不仅可以有效避免杂多酸(盐)活性组份在反应过程中的流失,还可以进一步提升含硅介孔分子筛的水热稳定性。该制备方法操作简单,易于放大。所制备的催化剂具有反应温度低,活性组分不易流失等优点,可应用于生物乙醇制乙烯等酸催化领域,具有较好的工业应用前景。(The invention relates to a catalyst with high stability for preparing ethylene by dehydrating bioethanol, and a preparation method and application thereof. The method is characterized in that raw materials for preparing the siliceous heteropoly acid (salt) are introduced in situ in the preparation process of the siliceous mesoporous molecular sieve, so that the siliceous heteropoly acid (salt) and the siliceous mesoporous molecular sieve material are synchronously generated in situ, and the generated siliceous heteropoly acid (salt) can be anchored in the framework of the siliceous mesoporous molecular sieve material through the connection of silicon-oxygen tetrahedrons because the raw materials of the siliceous heteropoly acid (salt) and the siliceous mesoporous molecular sieve material both contain silicate components. Not only can effectively avoid the loss of active components of heteropoly acid (salt) in the reaction process, but also can further improve the hydrothermal stability of the silicon-containing mesoporous molecular sieve. The preparation method is simple to operate and easy to amplify. The prepared catalyst has the advantages of low reaction temperature, difficult loss of active components and the like, can be applied to the field of acid catalysis for preparing ethylene from bioethanol, and has better industrial application prospect.)

1. A method for preparing a silicon-containing heteropoly acid (salt) and a silicon-containing mesoporous molecular sieve catalyst is characterized in that: firstly, dissolving a corresponding template agent required by a generated molecular sieve into water, adding concentrated hydrochloric acid with the mass concentration of 35-37% to adjust the pH value to 1-5, then respectively adding silicate ester and raw materials for preparing heteropoly acid containing silicon and/or heteropoly acid salt containing silicon, stirring for more than 30 minutes at 20-40 ℃, then transferring into a crystallization kettle, crystallizing for 12-72 hours at 60-150 ℃, performing suction filtration and drying, and roasting at 400-600 ℃ to remove the template agent; obtain the silicon-containing heteropoly acid (salt)/silicon-containing mesoporous molecular sieve catalytic material.

2. The method of claim 1, wherein: the active component of the catalyst contains silicon-containing heteropoly acid and/or silicon-containing heteropoly acid salt with the mass content of 5-60 percent, and the preferred mass content is 10-40 percent.

3. The method of claim 1, wherein: the active component siliceous heteropolyacid and/or siliceous heteropolyacid salt specifically comprises: one or more than two of silicomolybdic acid, silicotungstic acid, silicomolybdic vanadate, silicotungstic vanadate, sodium silicomolybdate, sodium silicotungstate, ammonium silicomolybdate, sodium silicomolybdovanadate and ammonium silicotungstic vanadate.

4. The method of claim 1, wherein: the raw materials for preparing the siliceous heteropolyacid and/or the siliceous heteropolyacid salt specifically include: one or more of ortho-silicic acid, metasilicic acid, sodium silicate, ammonium silicate, potassium silicate, sodium molybdate, ammonium molybdate, sodium tungstate, ammonium tungstate, sodium vanadate, and ammonium vanadate.

5. The method of claim 1, wherein: the silicon-containing mesoporous molecular sieve specifically comprises: one or more of mesoporous molecular sieves such as SBA series, MSU series, KIT series and the like.

6. The production method according to claim 1 or 5, characterized in that: the template agent specifically comprises: p123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer), nonylphenol polyoxyethylene ether, dodecyl polyoxyethylene ether, fatty alcohol polyoxyethylene ether, Tween-40 and/or octadecyl polyoxyethylene ether;

the silicate ester specifically includes: one or more of ethyl orthosilicate, methyl orthosilicate, propyl orthosilicate, butyl orthosilicate and ethyl polysilicate.

7. The method of claim 1, wherein: the crystallization temperature is 60-250 ℃ (preferably 100-.

8. A catalyst prepared by the method of any one of claims 1 to 7.

9. Use of the catalyst of claim 8 in a reaction for producing ethylene by dehydration of bioethanol.

10. Use according to claim 9, characterized in that:

filling the active components of the siliceous heteropoly acid and/or the siliceous heteropoly acid salt in a layering manner from top to bottom according to the gradually increasing sequence of the mass loading capacity of the active components, wherein the reaction tube is in a tower shape with a thin top and a thick bottom; under normal pressure, the mass purity of the bioethanol is 10-95%, the reaction temperature is 150-^-1The space velocity of the carrier gas is 500-15000h^-1。

Technical Field

The invention belongs to the field of preparation of novel catalytic materials, and particularly relates to a preparation method of a silicon-containing heteropoly acid (salt)/silicon-containing mesoporous molecular sieve catalyst.

Background

As one of the most important basic raw materials in the petrochemical field, ethylene is known as a "petrochemical parent", and at present, about 75% of petrochemical products are produced from ethylene. Ethylene production has become an important indicator of the state petrochemical industry. Currently, ethylene is obtained primarily by petroleum hydrocarbon cracking techniques. However, the method uses non-renewable fossil resources as raw materials, the selectivity of ethylene is low, and the subsequent separation process is complex. In recent years, smaller scale ethylene production has had a considerable market where large scale cracking units have not been commercially viable. With the annual decline of the reserves of fossil resources such as petroleum, the route of producing ethylene by dehydration of bioethanol using renewable resources as raw materials is receiving wide attention again. With the continuous progress of biological fermentation technology in recent years, the raw materials for preparing the bioethanol have been changed from initial grains to materials such as wood and straws, so that the cost of the bioethanol is greatly reduced. In addition, compared with the petroleum hydrocarbon cracking technology, the bioethanol dehydration technology has the advantages of simple process, small environmental pollution, easy product separation, small-scale preparation and the like. Therefore, this technology has shown increasing market competitiveness in recent years.

The existing process for preparing ethylene by ethanol dehydration mostly adopts alumina as a catalyst, the catalyst has better activity and selectivity, but the reaction temperature is usually more than 350 ℃, so that the energy consumption of the whole process is higher. In addition, the water content of the raw material ethanol also has certain requirements, and the bioethanol can be dehydrated only by first dehydrating and purifying, so that the energy consumption of the reaction process is further increased. CN 101837298B reports a small-grain ZSM-5 molecular sieve catalyst for preparing ethylene from bioethanol and a preparation method thereof, and the catalyst shows higher ethanol conversion rate and ethylene selectivity. Compared with the traditional alumina catalyst, the reaction temperature is also reduced to about 250 ℃. But still has the problems of short service life, easy activation and the like of the catalyst, and limits further industrial application of the catalyst.

In conclusion, the existing ethanol dehydration catalyst generally has the problems of high reaction temperature, easy loss of active components of the catalyst, poor water-resistant stability and the like. Aiming at the problems, the invention develops a novel method for preparing the catalyst for preparing the ethylene by dehydrating the bioethanol. The method introduces a certain amount of raw materials for preparing the siliceous heteropoly acid (salt) in the process of preparing the siliceous mesoporous molecular sieve, so that the siliceous heteropoly acid (salt) and the siliceous mesoporous molecular sieve material are synchronously generated in situ. Because both raw materials contain silicate components, the generated siliceous heteropoly acid (salt) can be anchored in the framework of the siliceous mesoporous molecular sieve material through the connection of silicon-oxygen tetrahedron. Not only can effectively avoid the loss of active components of heteropoly acid (salt) in the reaction process, but also can improve the hydrothermal stability of the mesoporous molecular sieve. Meanwhile, the mesoporous pore canal of the silicon-containing mesoporous molecular sieve can effectively inhibit the generation of carbon deposit species. In addition, according to the order that the loading capacity of the active components is gradually increased, the catalyst is filled from top to bottom in a layered mode, the traditional cylindrical reaction tube is optimized to be a tower-shaped reaction tube with a thin upper part and a thick lower part, and the leaching effect of water vapor generated by the reaction on the active components can be further reduced. Thereby further improving its stability. The preparation method is simple to operate and easy to amplify. Can be applied to the field of acid catalysis for preparing ethylene from bioethanol.

Disclosure of Invention

The invention aims to provide a preparation method of a catalyst for preparing ethylene by dehydrating bioethanol, and the catalyst prepared by the method can effectively improve the water-resistant stability of the catalyst on the premise of keeping the activity and the selectivity.

The invention provides a preparation method of a catalyst for preparing ethylene by dehydrating bioethanol, which comprises the steps of dissolving a corresponding template agent in water, adding hydrochloric acid to adjust the pH value to be 1-5, then respectively adding silicate ester and raw materials for preparing silicon-containing heteropoly acid (salt), stirring at 35 ℃ for more than 30 minutes, then transferring into a stainless steel crystallization kettle with a polytetrafluoroethylene lining, crystallizing at 60-150 ℃ for 12-72 hours, carrying out suction filtration, drying, and roasting at 400-600 ℃ to remove the template agent. To obtain a series of siliceous heteropoly acid (salt)/siliceous mesoporous molecular sieve catalytic materials with different loading capacity.

The active component of the catalyst contains silicon-containing heteropoly acid (salt) with the mass content of 5-60 percent and the preferential content of 10-40 percent.

The active component siliceous heteropoly acid (salt) specifically comprises: silicomolybdic acid, silicotungstic acid, silicomolybdic vanadate, silicotungstic vanadate, sodium silicomolybdate, sodium silicotungstate, ammonium silicomolybdate, sodium silicomolybdic vanadate, ammonium silicotungstic vanadate and one or more than two of the components are mixed for use.

The raw materials for preparing the siliceous heteropoly acid (salt) specifically comprise: ortho-silicic acid, metasilicic acid, sodium silicate, ammonium silicate, potassium silicate, sodium molybdate, ammonium molybdate, sodium tungstate, ammonium tungstate, sodium vanadate, ammonium vanadate, and one or more of the above components.

The silicon-containing mesoporous molecular sieve specifically comprises: SBA series, MSU series, KIT series and other mesoporous molecular sieves.

The template agent specifically comprises: p123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer), nonylphenol polyoxyethylene ether, dodecyl polyoxyethylene ether, fatty alcohol polyoxyethylene ether, Tween-40, octadecyl polyoxyethylene ether and one or more of the components.

The silicate ester specifically includes: ethyl orthosilicate, methyl orthosilicate, propyl orthosilicate, butyl orthosilicate, ethyl polysilicate and one or more of the components are mixed for use.

The crystallization temperature is 60-150 ℃, the crystallization time is 12-72h, and the product is filtered, dried and roasted at the temperature of 400-600 ℃.

According to the order that the loading capacity of the active component siliceous heteropoly acid and/or siliceous heteropoly acid salt is gradually increased, the active component siliceous heteropoly acid and/or siliceous heteropoly acid salt is filled layer by layer from top to bottom, and the appearance of the reaction tube is a tower shape with a thin top and a thick bottom.

The application of the catalyst in the reaction of preparing ethylene by dehydrating the bioethanol is characterized in that under the normal pressure condition, the purity of the bioethanol is 10-95%, the reaction temperature is 150-300 ℃, and the volume space velocity of the raw material ethanol is 0.1-15h^-1The space velocity of the carrier gas is 500-15000h^-1Under the condition, the high-efficiency conversion of the bioethanol can be realized, and higher stability is obtained at the same time.

Compared with the reported preparation method of the catalyst for preparing ethylene by dehydrating bioethanol, the method has the following advantages: during the preparation of silicon-containing mesoporous molecular sieve, certain amount of material for preparing silicon-containing heteropoly acid (salt) (sodium silicate, ammonium tungstate, ammonium molybdate, ammonium vanadate, etc.) is introduced to make the silicon-containing heteropoly acid (salt) and silicon-containing mesoporous molecular sieve grow synchronously. Because both raw materials contain silicate components, the generated siliceous heteropoly acid (salt) can be 'anchored' in the framework of the siliceous mesoporous molecular sieve material through the connection of silicon-oxygen tetrahedron. Not only can effectively avoid the loss of active components of heteropoly acid (salt) in the reaction process, but also can improve the hydrothermal stability of the mesoporous molecular sieve. In addition, according to the order that the loading capacity of the active components is gradually increased, the catalyst is filled from top to bottom in a layered mode, the traditional cylindrical reaction tube is optimized to be a tower-shaped reaction tube with a thin upper part and a thick lower part, and the leaching effect of water vapor generated by the reaction on the active components can be further reduced. Thereby further improving its stability. The preparation method is simple to operate and easy to amplify. The prepared catalyst has the advantages of low reaction temperature, difficult inactivation of active components and the like, and can be applied to the field of acid catalysis for preparing ethylene from bioethanol.

In addition, the mesoporous pore canal of the silicon-containing mesoporous molecular sieve can effectively inhibit the generation of carbon deposit species. Thereby further improving its stability. The catalyst of the invention is used, the bioethanol solution with the mass fraction of 5-95% is used as the reaction raw material, the reaction temperature is 150 ℃ and 300 ℃, and the volume space velocity of the raw material ethanol is 0.1-15h^-1The space velocity of the carrier gas is 500-15000h^-1Under the condition, the high-efficiency conversion of the bioethanol can be realized, and higher stability is obtained at the same time. The preparation method is simple to operate and easy to amplify. The prepared catalyst has the advantages of low reaction temperature, difficult loss of active components and the like, can be applied to the field of acid catalysis for preparing ethylene from bioethanol, and has better industrial application prospect.

Detailed Description