Hydrothermally stable HZSM-5 zeolite catalysts for the transformation of crude bio-oil into hydrocarbons

The hydrothermal stability of two alternative catalysts for the production of hydrocarbons from crude bio-oil has been studied. The valorisation of crude bio-oil from lignocellulosic biomass pyrolysis has been studied by means of a two-step process (thermal-catalytic) and co-feeding methanol, which are strategies that attenuate both the deposition of pyrolytic lignin and catalyst deactivation by coke deposition. A catalyst prepared based on a HZSM-5 zeolite with a SiO2/Al2O3 ratio of 80 produces a C2–C4 olefins yield of 32 wt% at 500 °C and with a space time of 0.371 (g of catalyst) h (g of oxygenates)−1. The modification of a HZSM-5 zeolite (SiO2/Al2O3 ratio of 30) by impregnation with 1 wt% of Ni produces a yield of aromatics of 42 wt% for the same temperature and space time. These catalysts are very active for bio-oil valorisation (conversion above 90%) with high hydrothermal stability, given that their kinetic behaviour is similar throughout 10 successive reaction–regeneration cycles carried out under severe operating conditions.

Figure optionsDownload as PowerPoint slideResearch highlights▶ Two-step process (thermal-catalytic) and co-feeding of methanol attenuates pyrolytic lignin deposition and catalyst deactivation. ▶ HZSM-5 zeolite catalyst with a SiO2/Al2O3 ratio of 80 produces a C2–C4 olefins yield of 32 wt% at 500 °C and with a space time of 0.371 (g of catalyst) h (g of oxygenates)−1. ▶ HZSM-5 zeolite with SiO2/Al2O3 ratio of 30 and modified by impregnation with 1 wt% of Ni produces a yield of aromatics of 42 wt%. ▶ Both catalysts are very active for bio-oil valorisation (conversion above 90%) with high hydrothermal stability.