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Hydrogenation of CO2 to Aromatics over Fe–K/Alkaline Al2O3 and P/ZSM-5 Tandem Catalysts
Industrial & Engineering Chemistry Research ( IF 3.8 ) Pub Date : 2020-09-28 , DOI: 10.1021/acs.iecr.0c03598
Chengyi Dai 1, 2 , Xiao Zhao 1 , Borui Hu 1 , Jiaxing Zhang 3 , Qingqing Hao 1, 2 , Huiyong Chen 1, 2 , Xinwen Guo 3 , Xiaoxun Ma 1, 2
Affiliation  

A highly efficient tandem catalyst comprising an iron–potassium bimetal-modified alkaline Al2O3 catalyst and a phosphorus-modified ZSM-5 zeolite (denoted as Fe–K/a-Al2O3&P/ZSM-5) for directly hydrogenating CO2 to aromatics is reported. The hydrogenation conversion route of CO2 → olefins → aromatics on the tandem catalyst is demonstrated. The Fe–K/a-Al2O3 catalyst solely serves as a metal active center to hydrogenate CO2 to lower olefin intermediates with high selectivity, and the P/ZSM-5 zeolite, which provides acid sites, can rapidly convert lower olefin intermediates to aromatics by polymerization and dehydrocyclization. Moreover, the addition of alkaline Al2O3 as the support leads to the improved dispersion of the Fe–K bimetal and subsequently promotes CO2 adsorption, thereby inhibiting the adsorption of H2 and benefitting the formation of lower olefin intermediates. Strong acid sites of HZSM-5 zeolites with low Si/Al ratios are essential for the formation of aromatics. The appropriate proximity of two active components in the tandem catalyst is critical to the highly selective catalytic process for hydrogenating CO2 to aromatics. The granule-mixing catalyst maintains strong acidity and CO2 adsorption capacity, boosting the hydrogenation of CO2 to aromatics. Phosphorus modification changes the acid strength of HZSM-5 zeolites and increases the amount of medium-strength acid sites, further promoting the generation of aromatics, which exhibits a 36.4% CO2 conversion as well as a 35.5% selectivity for aromatics among the carbon products within CO, and the tandem catalyst is suitable at a low H2/CO2 ratio with merely a 10.2% byproduct CO selectivity. In addition, HZSM-5 with a low phosphorus loading is conducive to the aromatization of lower olefins, and the phosphorus loading of 0.8 wt % is found to be suitable.

中文翻译:

Fe–K /碱性Al 2 O 3和P / ZSM-5串联催化剂上将CO 2加氢成芳烃

一种高效的串联催化剂,包括铁-钾双金属改性的碱性Al 2 O 3催化剂和磷改性的ZSM-5沸石(表示为Fe–K / a-Al 2 O 3&P / ZSM-5),用于直接加氢据报道,CO 2为芳烃。说明了串联催化剂上CO 2 →烯烃→芳烃的加氢转化路线。Fe–K / a-Al 2 O 3催化剂仅充当金属活性中心以氢化CO 2具有高选择性的低烯烃中间体,提供酸位的P / ZSM-5沸石可通过聚合和脱氢环化作用迅速将低烯烃中间体转化为芳烃。此外,添加碱性Al 2 O 3作为载体可改善Fe-K双金属的分散性,并随后促进CO 2的吸附,从而抑制H 2的吸附并有利于形成低级烯烃中间体。低Si / Al比的HZSM-5沸石的强酸位对于形成芳族化合物至关重要。串联催化剂中两种活性成分的适当接近度对于氢化CO 2的高选择性催化过程至关重要芳香剂。颗粒混合催化剂保持强酸性和CO 2吸附能力,促进了CO 2加氢成芳烃。磷改性改变了HZSM-5沸石的酸强度,增加了中强度酸位的数量,进一步促进了芳烃的生成,该芳烃在碳产品中的CO 2转化率为36.4%,对芳烃的选择性为35.5%。串联催化剂适合于低H 2 / CO 2比,副产物CO选择性仅为10.2%。另外,磷负载量低的HZSM-5有利于低级烯烃的芳构化,并且发现磷负载量为0.8重量%是合适的。
更新日期:2020-10-29
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