Microalgae hydrothermal liquefaction and derived biocrude upgrading with modified SBA-15 catalysts

Abstract

In this study, a novel route was proposed for microalgae biofuel production by catalytic upgrading of Chlorella hydrothermal liquefaction (HTL) derived biocrude. Al-SBA-15, CuO/Al-SBA-15, ZuO/Al-SBA-15, and CuO-ZnO/Al-SBA-15 catalysts were synthesized in a facile, one-pot way, and tested for methyl palmitate decarboxylation and biocrude upgrading without H₂ addition. These modified SBA-15 catalysts enhanced alkane selectivity of methyl palmitate decarboxylation from 7.6 wt% up to 79.6 wt% at 340-350 °C. FT-IR, TG and GC-MS characterizations were employed to identify the composition and properties of the upgraded bio-oils. Compared with thermal upgrading, modified SBA-15 catalysts enriched the yield of low boiling point compounds, and the content of heavy bio-oil (>400 °C) declined from 9.57 wt% to 1.89 wt%. Hydrocarbon yield was greatly enriched on the catalysts, and aromatics predominant on Al-SBA-15 while aliphatics abundant on metal oxide(s) supported catalysts. The hydrocarbon yield was increased from 25.1 wt% (thermal) to 65.7 wt% on the CuO/Al-SBA-15.

Keywords: Bio-oil upgrading; Hydrocarbon yield; Hydrothermal liquefaction; Methyl palmitate decarboxylation; SBA-15 catalyst.