油脂一步加氢制异构烷烃催化反应机制的研究

Lipids hydrotreatment to produce iso-alkanes has found great applications in high quality diesel and jet fuel production, because of the unique properties of the iso-alkanes product such as high cetane number and low freezing point. Recently, we have reported a new method for directly converting lipids to iso-alkanes over the supported metal zeolite catalyst with one dimensional ten-membered-ring channels in a single-step hydrotreatment process, in which the lipids feedstock was completely converted and the iso-alkanes were the main product. In this proposal, the hydrogenation, deoxygenation and isomerization properties of the catalyst will be finely tuned by investigation of the influence of zeolite modification and metal loading conditions. The mechanism of C-C and C-O cracking will be specially studied from the immediate formation in the catalyst evaluation by using model ester reactant such as tristearin and in-situ reaction by using small molecular probe such as methyl acetate as reactant. The structure-activity relationship of the catalyst will be demonstrated from the result of structure changes in the in-situ characterization and the study of the ex-situ characterization and evaluation. Our study will provide new recognition for selective conversion of lipids as well as designing high selective catalyst in the single-step hydrotreatment process..

油脂加氢制得的异构烷烃具有高十六烷值、低凝点等特性，可作为调和组分改善现有柴油和航空煤油品质，具有重要的应用价值。申请人最近报道了一种油脂在负载型金属/十元环一维直孔道分子筛催化剂上一步加氢制异构烷烃的新方法。本项目拟基于前期研究结果，通过深入研究分子筛改性和金属负载条件的影响，掌握催化剂上加氢、脱氧和异构化活性位的调变规律；通过硬脂酸甘油酯等模型原料评价反应和乙酸甲酯等探针分子原位反应，跟踪油脂加氢中间产物的形成过程，深入理解酯类分子加氢催化转化过程中C-C键、C-O键断裂行为，揭示油脂一步加氢制异构烷烃的脱氧机理；通过采用原位/离位表征手段，研究催化剂在反应时的结构变化，结合催化剂评价结果，阐明催化剂结构和催化活性的构效关系。本研究工作为设计高选择性油脂一步加氢制异构烷烃催化剂和实现油脂定向转化提供理论依据，具有重要的科学意义。

油脂加氢制得的异构烷烃具有高十六烷值、低凝点等特性，可作为调和组分改善现有柴油和航空煤油品质，具有重要的应用价值。本项目工作通过对一维十元环孔道分子筛载体后处理方式、金属负载方式和还原方法的探索和优化，调控了催化剂的酸性、孔结构和负载金属电子状态；通过模型原料反应评价和探针分子原位反应，深入研究了油脂转化过程中C-C键、C-O键断裂行为，提出油脂脱氧机理；结合催化剂表征，确定了催化剂结构和催化活性的构效关系，设计并制备同时具有高选择性脱羧和异构化性能的催化剂；探索了预成型制磷酸铝分子筛的新方法，研制出具有优异异构化性能的成型磷酸铝分子筛催化材料。本项目开展的研究，为设计高选择性油脂一步加氢制异构烷烃催化剂和实现油脂定向转化提供理论依据，具有重要的科学意义。