(678c) Evaluating Zeolite Supported Pt/ZIF-67 with Low Noble-Metal Loading for the Deoxygenation of Saturated and Unsaturated Fatty Acids

Biomass-derived transportation fuels provide the opportunity for both increased national energy security and reduced greenhouse gas emissions when compared to conventional petroleum fuels. Many processes exist for the production of fuels from biomass including pyrolysis, hydrothermal liquefaction, homogeneous catalysis, and heterogeneous catalysis. Our research is focused on the use of heterogeneous catalysts for the deoxygenation of abundant fatty acids found in vegetable oils, algae oils, and animal fats. The composition of many non-edible plants with high oil content is divided into saturated, unsaturated, and polyunsaturated fatty acids. Across the field of fatty acid upgrading, most researchers have focused on model compounds lauric (12:0), stearic (18:0), and oleic acid (18:1).

In the current study, we evaluate the activity of low platinum loading ZIF-67/zeolite 5A catalysts for the deoxygenation of polyunsaturated linoleic acid (18:2) under nitrogen, hydrogen, and carbon dioxide atmospheres. The results show that a higher degree of unsaturation can cause lower yields to desired alkanes due to the increased reductive demand of the polyunsaturated backbone. Overall, yields to heptadecane (C₁₇) from linoleic acid were as high as 65.3, 63.5, and 58.4% under H₂, CO₂, and N₂ atmospheres, respectively. Reactions in H₂ followed hydrodeoxygenation while N₂ and CO₂ resulted in decarboxylation pathways. Recyclability and textural properties of the catalyst were explored for all reactive atmospheres showing a slight decrease in surface area, good maintenance of crystallinity, and high stability at elevated temperatures by thermogravimetric analysis.