阅读说明：本技术 一种合成气直接制乙醇的催化剂及应用 (Catalyst for directly preparing ethanol from synthesis gas and application thereof ) 是由 苏海全 屈皓 贺思慧 苏越 孙健 于 2020-03-26 设计创作，主要内容包括：一种用于合成气直接制乙醇的催化剂,各组分的质量百分含量为：硒化钼65-95%,助剂5-35%。本发明涉及的催化剂总醇选择性高、总醇中乙醇含量高、适合于H<Sub>2</Sub>/CO比较低的合成气,具有良好的应用前景。(A catalyst for directly preparing ethanol from synthesis gas comprises the following components in percentage by mass: 65-95% of molybdenum selenide and 5-35% of auxiliary agent. The catalyst related by the invention has high total alcohol selectivity and high ethanol content in the total alcohol, and is suitable for H 2 The synthesis gas with low CO ratio has good application prospect.)

1. A catalyst for directly preparing ethanol from synthesis gas and an application thereof are characterized in that the catalyst comprises the following components: 65-95 wt% of molybdenum selenide and 5-35 wt% of assistant.

2. The catalyst of claim 1 wherein the promoter is one or more of potassium carbonate, potassium oxide, potassium hydroxide or potassium acetate.

3. The catalyst of claim 1, wherein the catalyst is used in the preparation of ethanol or lower alcohol mixture from syngas.

4. The catalyst according to claim 1, characterized in that the catalyst is used under the conditions: h in synthesis gas₂The volume ratio of/CO is 0.8-1.2, the reaction temperature is 300-400 ℃, the reaction pressure is 8-12 MPa, and the space velocity is 1000-10000 h^-1。

Technical Field

The invention relates to a catalyst for preparing ethanol from synthesis gas and application thereof, in particular to a molybdenum selenide catalyst for preparing ethanol from synthesis gas and application thereof.

Background

Ethanol is an important chemical raw material, fuel and fuel additive, and has very wide application in various fields of chemical industry, pharmacy, energy sources and the like. On one hand, ethanol is used as a fuel additive, so that the combustion efficiency of fuel can be effectively improved, the octane number of the fuel is increased, and the emission of CO is reduced; on the other hand, the ethanol prepared from coal through synthesis gas does not contain N, S and other elements, and does not generate NOx, SOx and other pollution after combustion, thereby being an environment-friendly clean fuel. In addition, ethanol can also be used as solvent for nitrolacquer, varnish, cosmetics, ink, paint remover, etc., and raw material for producing pesticide, medicine, rubber, plastic, rayon, detergent, etc., and can also be used as antifreeze, adhesive, disinfectant, etc. The method for preparing ethanol by CO catalytic hydrogenation is not only an important branch of C1 chemical research, but also one of important ways for realizing high-efficiency and clean utilization of coal resources. Although researchers have done a lot of research works in this field, the large-scale industrial production of ethanol by catalytic hydrogenation of CO has not been realized at present, and the main reason is that no catalyst suitable for industrial production has been developed. The research of the catalyst with excellent performance and low cost is still the key point of the research in the field of preparing ethanol from synthesis gas.

Chinese patent (201610898404.6) reports a catalyst for producing ethanol from synthesis gas, which is composed of copper oxide, zirconium oxide, potassium oxide and a carrier. The catalyst is reduced and then is subjected to reaction in H₂/CO＝2，6MPa、250℃、6000h^-1Under the conditions of (1), the conversion rate of CO is 15.8%, alcohols, hydrocarbons and CO₂The selectivities (Cmol.%) were 23.6, 30.7, 22.4, respectively, methanol, ethanol, propanol, butanol and C in alcohol₅₊The alcohol distribution (wt.%) was 39.2, 55.7, 2.4, 2.3 and 0.7, respectively. Although the catalyst exhibits excellent ethanol selectivity, the higher hydrocarbon selectivity remains to be optimized.

The noble metal rhodium catalyst can synthesize ethanol with high selectivity under mild conditions. Chinese patent (201410589965.9) reports that a catalyst for preparing ethanol from synthesis gas consisting of rhodium, iron and aluminum oxide has the reaction temperature of 280 ℃, the reaction pressure of 3MPa and the gas space velocity of 5400h^-1、H₂And a CO molar ratio of 2, the conversion rate of CO is up to 32.5%, and the selectivity of the prepared ethanol is 39.2%. The higher cost of noble metal catalysts also limits further applications of the catalysts.

Among various catalyst systems for preparing ethanol from synthesis gas, molybdenum-based catalysts are considered as the most promising catalyst systems due to their high alcohol selectivity and excellent sulfur resistance, and have received extensive attention from researchers. The application of molybdenum sulfide-based catalyst in the preparation of low carbon alcohol from synthesis gas is first reported in the patent of the U.S. Dow chemical company in 1986 (EP 0170973), and the catalyst system has good sulfur resistance, low water content of low carbon alcohol products and high alcohol selectivity of the products. The domestic patents on the molybdenum sulfide-based catalyst for preparing the low-carbon alcohol from the synthesis gas mainly include CN 1431049, CN1631527, CN 1663683 and CN 108325548. Wherein, it is worth mentioning that the auxiliary agents such as Ni, Fe, Mn, K, etc. are added into the molybdenum sulfide catalyst to obtain the low-carbon alcohol catalyst prepared from the synthesis gas with excellent performance, the total alcohol selectivity can reach more than 60%, but the main product of the catalyst system is methanol.

Despite MoS₂Based on the catalyst, alcohol products have higher selectivity, but the traditional MoS₂Catalyst-based alcohol products are predominantly methanol, typically accounting for over 50% of the total alcohol, which also greatly limits MoS₂The application prospect of the base catalyst. For MoS₂Base catalyst C₂₊The problem of low alcohol selectivity has been a great deal of research by researchers. It is generally believed that the addition of transition metals (e.g., Fe, Co, Ni) is effective in increasing MoS₂Catalytic activity of the base catalyst and C₂₊Alcohol selectivity, but a large amount of hydrocarbon byproducts can be generated due to high hydrogenation activity of Fe, Co and Ni. Meanwhile, these transition metals are lost due to the formation of carbonyl compounds having a low boiling point during the reaction, thereby causing a decrease in catalyst activity. Therefore, synthesizing a catalyst with excellent overall alcohol selectivity and ethanol selectivity at the same time remains a challenge in this field.

Disclosure of Invention

The invention provides a catalyst for preparing ethanol from synthesis gas, which has high ethanol selectivity and is suitable for preparing ethanol from low H/C ratio, and an application field and reaction process conditions thereof.

The catalyst of the invention comprises the following components: 65-95 wt% of molybdenum selenide and 5-35 wt% of assistant. Wherein the auxiliary agent is one or more of potassium carbonate, potassium oxide, potassium hydroxide or potassium acetate.

The application field of the catalyst of the invention is the preparation of ethanol or low-carbon mixed alcohol from synthesis gas.

The catalyst of the invention is used under the following conditions: h in synthesis gas₂Volume ratio of/CO of 08-1.2, the reaction temperature is 300-400 ℃, the reaction pressure is 8-12 MPa, and the space velocity is 1000-10000 h^-1。

Detailed Description