Hydrotreating of Methyl Laurate and Crude Coconut Oil over PtSn/MgO/ZSM-5 Catalysts

The involvement of base sites in the deoxygenation pathways of fatty acid methyl esters, were investigated using a series of PtSn/MgO(m)/ZSM-5 (m = 1, 2.5, and 5 wt%) bifunctional catalysts were prepared by incipient wetness impregnation and applied to the hydrotreating of methyl laurate (ML) and crude coconut oil (CCO). Higher MgO content decreased Brønsted acidity and suppressed the reducibility of Sn species, indicating strong metal-support and acid-base interactions. Catalytic evaluation in a continuous fixed-bed reactor revealed that PtSn/ZSM-5 favored the hydrodeoxygenation (HDO) pathway for ML, whereas MgO-modified catalysts progressively shifted the reaction toward decarboxylation (DCO) through selective modification of the acid-base site balance and hydrogen availability. Single-step hydrotreating of CCO over PtSn/MgO(2.5)/HZSM-5 achieved a C8-C16 hydrocarbon yield of 30.4 % at 375 °C, 1 MPa, a hydrogen/CCO ratio of 500 mL mL−1, and a WHSV of 1.5 h−1, and suppressed excessive cracking and light gas formation. The product consisted mainly of paraffins (80.9 wt%), with low oxygenates (<1 wt%) and moderate olefins (4.7 wt%). MgO addition reduced hydrogen consumption by optimizing the acidity and promoting the DCO pathway, indicating more effective design of hydrogen-efficient bifunctional catalysts for selective and sustainable aviation fuel production.