Catalytic fast pyrolysis of wood and alcohol mixtures in a fluidized bed reactor

Abstract

Catalytic fast pyrolysis (CFP) of pine wood, alcohols (methanol, 1-propanol, 1-butanol and 2-butanol) and their mixtures with ZSM-5 catalyst were conducted in a bubbling fluidized bed reactor. The effects of temperature and weight hourly space velocity (WHSV) on the product carbon yields and selectivities of CFP of pure pine wood and methanol were investigated. A maximum carbon yield of petrochemicals (aromatics + C₂–C₄olefins + C₅ compounds) from pine wood of 23.7% was obtained at a temperature of 600 °C and WHSV of 0.35 h⁻¹. A maximum petrochemical yield from methanol of 80.7% was obtained at a temperature of 400 °C and WHSV of 0.35 h⁻¹. Thus, the optimal conditions for conversion of pine wood and methanol are different. The CFP of pine wood and methanol mixtures was conducted at 450 °C and 500 °C. The hydrogen to carbon effective (H/C_eff) ratio of the feed was adjusted by changing the relative amount of methanol and wood. The petrochemical yield was a function of the H/C_eff ratio and more petrochemicals are produced from biomass when methanol is added to the CFP process. Co-feeding of ¹²C pine wood and ¹³C methanol was carried out at 450 °C. The isotopic study showed that all the hydrocarbon products contained mixtures of ¹²C and ¹³C, indicating that the carbon is mixed within the zeolite. However, the distribution of carbon was skewed depending on the product. The toluene, xylene, propylene and butenes contained more ¹³C. The naphthalene and ethylene contain more ¹²C. Wood was also co-processed with 1-propanol, 1-butanol, and 2-butanol, which showed a similar effect as methanol with an increasing petrochemical yield with an increasing H/C_eff ratio of the feed. This paper demonstrates that CFP can selectively produce a mixture of compounds where the overall yield is a function of the H/C_eff ratio of the feed.