Liu Sibao, Simonetti Trent, Zheng Weiqing, Saha Basudeb
Catalysis Center for Energy Innovation and Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, 19716, USA.
ChemSusChem. 2018 May 9;11(9):1446-1454. doi: 10.1002/cssc.201800321. Epub 2018 Apr 19.
High yields of diesel-range alkanes are prepared by hydrodeoxygenation of vegetable oils and waste cooking oils over ReO -modified Ir/SiO catalysts under mild reaction conditions. The catalyst containing a Re/Ir molar ratio of 3 exhibits the best performance, achieving 79-85 wt % yield of diesel-range alkanes at 453 K and 2 MPa H . The yield is nearly quantitative for the theoretical possible long-chain alkanes on the basis of weight of the converted oils. The catalyst retains comparable activity upon regeneration through calcination. Control experiments using probe molecules as model substrates suggest that C=C bonds of unsaturated triglycerides and free fatty acids are first hydrogenated to their corresponding saturated intermediates, which are then converted to aldehyde intermediates through hydrogenolysis of acyl C-O bonds and subsequently hydrogenated to fatty alcohols. Finally, long-chain alkanes without any carbon loss are formed by direct hydrogenolysis of the fatty alcohols. Small amounts of alkanes with one carbon fewer are also formed by decarbonylation of the aldehyde intermediates. A synergy between Ir and partially reduced ReO sites is discussed to elucidate the high activity of Ir-ReO /SiO
在温和的反应条件下，通过植物油和废食用油在ReO修饰的Ir/SiO催化剂上进行加氢脱氧反应，可制备出高产率的柴油范围烷烃。Re/Ir摩尔比为3的催化剂表现出最佳性能，在453K和2MPa氢气压力下，柴油范围烷烃的产率达到79 - 85wt%。基于转化油的重量，该产率对于理论上可能的长链烷烃而言几乎是定量的。通过煅烧再生后，催化剂保持了相当的活性。使用探针分子作为模型底物的对照实验表明，不饱和甘油三酯和游离脂肪酸的C=C键首先加氢生成相应的饱和中间体，然后通过酰基C-O键的氢解转化为醛中间体，随后加氢生成脂肪醇。最后，脂肪醇通过直接氢解形成无碳损失的长链烷烃。还讨论了Ir与部分还原的ReO位点之间的协同作用，以阐明Ir-ReO/SiO的高活性。
