Production of normal paraffins with an even carbon number via selective hydrodeoxygenation of palm fatty acid distillate over Pt-Sn catalysts

Abstract

Two series of supports, SAPO-11 (Si/Al: 0-0.4) and alumina-coated SBA-15 (Al2O3: 0-20 wt %), with different pore structures were synthesized. Subsequently, the PtSn bimetallic catalysts supported on these supports were prepared using a coimpregnation method and were characterized by N2 adsorption measurement, pyridine-adsorbed Fourier transform infrared, CO chemisorption, and H2-TPR. The catalytic performances of the catalysts in the hydrotreatment of palm fatty acid distillate (PFAD) were tested using a fixed-bed flow reactor system. PtSn/ALPO-11 (Si/Al: 0) showed the highest n-C16,18 selectivity (66.4%) among the SAPO-11-based catalysts, and PtSn/20Al/SBA-15 (20% Al2O3) showed the highest n-C16, n-C18 selectivity (61.5%) among the SBA-15-based catalysts. It was found that higher Brønsted acid content on the catalyst showed higher isomerization selectivity. Based on the comparison of PtSn/SAPO-11 (0.1) and PtSn/10Al/ SBA-15, the mesoporous structure favored hydrodeoxygenation activity. Also, it was suggested that Brønsted acid affected the structure of active sites and highly dispersed Pt favored formation of n-hexadecane and n-octadecane.