Production of High-Value Chemicals by Biomass Pyrolysis with Metal Oxides and Zeolites

The catalysis of biomass pyrolysis vapors by metal oxide and zeolite was proposed to produce high-value chemicals. Metal oxides CaO and Al2O3 exhibited strong reactivity with acids and phenols with methoxyl. Acetic acid was reduced by 65.2% and 23.3% under CaO and Al2O3 catalysis, respectively, whereas guaiacols decreased by 40.4% and 27.6%, respectively. The neutralization with acids and the catalytic effect on the oxygenate groups were the main reactions of CaO, while deoxygenation on Lewis sites mainly occurred during the catalyzation by Al2O3. Since the vapors were cracked into low molecular compounds, the combination of CaO and microporous HZSM-5 showed a promotion effect on generating aromatic hydrocarbons, with 56.0% and 44.7% increases of benzene and toluene, respectively. A dual catalyst composed of CaO and mesoporous Al-MCM-41 exhibited a promotion of phenols, furans, etc., due to its large pores, which permitted more vapor to react at acid sites. The enhancement of phenols and furans was 81.2% and 8.78%, respectively. At last, the optimal temperatures for the two dual catalysts, CaO and HZSM-5 and CaO and Al-MCM-41, were 800 degrees C and 700 degrees C, respectively.