造孔剂诱导合成FeCoCuAl催化剂及其与ZSM-5复合催化CO_(2)加氢制高碳烃性能

Pore-forming agent induced synthesis of FeCoCuAl catalysts and their performance in hydrogenation of CO_(2) to high carbon hydrocarbons with ZSM-5

CO_(2)加氢制高碳烃(C_(5+))是合成高值化学品和燃料的重要途径之一,这既可以实现碳减排,又有助于缓解能源压力。采用沉淀法和等体积浸渍法制备了K、Na修饰的FeCoCuAl催化剂,考察了造孔剂1,3,5-苯三甲酸(BTA)对其在CO_(2)催化加氢制高碳烃反应(温度为300℃、压力为2.0MPa、原料气n(H_(2)):n(CO_(2))=3:1且空速为3600h^(-1)、时间为6h)中催化性能的影响。在FeCoCuAl-20.0BTA催化剂(n(BTA):n(Fe)=20.0%)中引入ZSM-5分子筛,构建了一系列复合催化剂,并研究了其在CO_(2)催化加氢制高碳烃反应中的催化性能。结合N2吸/脱附、X射线衍射(XRD)、H_(2)-程序升温还原(H2-TPR)、CO_(2)程序升温脱附(CO_(2)-TPD)和H_(2)升温脱附(CO_(2)-TPD)等对催化剂的理化性质进行了表征,采用GC-MS对产物油相成分进行了分析。结果表明,与FeCoCuAl催化剂相比,FeCoCuAl-BTA催化剂的比表面积、孔容等均增大,并生成了更多的表面活性物种(Fe或Fe-Co合金),从而使得FeCoCuAl-BTA催化剂在CO_(2)催化加氢反应中表现出更好的催化性能。FeCoCuAl-20.0BTA催化剂的CO_(2)转化率和C_(5+)选择性分别可达70%和42%。FeCoCuAl-20.0BTA催化剂催化CO_(2)加氢生成的产物以C_(2)~C_(4)产物为主,而在FeCoCuAl-20.0BTA催化剂与ZSM-5分子筛以质量比为1.0、颗粒机械混合方式构建的复合催化剂上,FeCoCuAl-20.0BTA上生成的C_(2)~C_(4)产物可在ZSM-5分子筛上发生原位链增长、异构化和芳构化反应,从而提高了CO_(2)转化率和C_(5+)选择性,分别达到79%和66%。

CO_(2) hydrogenation to high-carbon hydrocarbons(C_(5+))is one of the important ways to synthesize high-value chemicals and fuels,which can achieve carbon emission reduction as well as help to alleviate energy pressure.K-and Na-modified FeCoCuAl catalysts were prepared by precipitation and iso-volumetric impregnation methods,and the effects of the pore-forming agent 1,3,5-benzenetricarboxylic acid(BTA)on their catalytic performance in CO_(2)-catalyzed hydrogenation to high-carbon hydrocarbons reaction(temperature of 300℃,pressure of 2.0 MPa,n(H_(2)):n(CO_(2))=3:1 and space velocity of 3600 h^(-1) of feed gas,reaction for 6 h)were investigated.ZSM-5 molecular sieve was introduced into FeCoCuAl-20.0BTA catalyst(n(BTA):n(Fe)=20.0%)to construct a series of composite catalysts and their catalytic performance in the reaction of catalytic hydrogenation of CO_(2) to high-carbon hydrocarbons was investigated.The physicochemical properties of the catalysts were characterized by combining N_(2) adsorption/desorption,X ray diffraction(XRD),H_(2)-temperature programmed reduction(H_(2)-TPR),CO_(2) temperature programmed desorption(CO_(2)-TPD),and H_(2) temperature programmed desorption(CO_(2)-TPD),and the oil-phase compositions of the products were analyzed by GC-MS.The results show that compared with FeCoCuAl catalysts,the specific surface area and pore volume of FeCoCuAl-BTA catalysts increase,and generate more surface-active species(Fe or Fe-Co alloy),which lead to better catalytic performance of FeCoCuAl-BTA catalysts in CO_(2) catalytic hydrogenation reaction.The CO_(2) conversion rate and C5+selectivity of FeCoCuAl-20.0BTA catalyst are up to 70%and 42%,respectively,and the products generated from CO_(2) hydrogenation catalyzed by FeCoCuAl-20.0BTA catalyst are mainly C_(2)~C_(4) products,while on the composite catalyst constructed with FeCoCuAl-20.0BTA catalyst and ZSM-5 molecular sieve in the form of mechanical mixing of particles with the mass ratio of 1.0,the C_(2)~C_(4) products generated on FeCoCuAl-20.0BTA can undergo in situ chain growth,isomerization and aromatization reactions on ZSM-5 molecular sieves,which lead to the improvement of CO_(2) conversion rate and C_(5+) selectivity,reaching 79% and 66%,respectively.