Reactive catalytic fast pyrolysis of biomass to produce high-quality bio-crude

Abstract

Reactive catalytic fast pyrolysis (RCFP) of biomass with atmospheric pressure hydrogen was investigated in a lab-scale fluidized bed reactor with varying reaction conditions (temperature and hydrogen concentration) and catalysts. Presence of atmospheric hydrogen with candidate RCFP catalysts was found to improve the yield and quality of bio-crude and minimize the char and coke formation. A molybdenum-based catalyst was the most effective at hydrodeoxygenating biomass pyrolysis vapors to produce a hydrocarbon-rich bio-crude intermediate with low oxygen content (<10 wt%). Higher hydrogen concentration and moderate reaction temperature (450 °C) favored higher bio-crude yields and quality. A yield of 43.2 C% in the C₄₊ organic fraction with as low as 6.2 wt% oxygen in the liquid was obtained under optimized reaction conditions. The resulting bio-crude contained primarily aliphatic and aromatic hydrocarbons, with small amounts of simple ketones, furans, and phenols. Up to 41.5% carbon in the biomass feed was converted into gas and condensable hydrocarbons with 29.7% in the condensable C₄₊ fraction. The improved bio-crude quality is expected to be more compatible with existing petroleum refining infrastructure.