Multifaceted effects of HZSM-5 (Proton-exchanged Zeolite Socony Mobil-5) on catalytic cracking of pinewood pyrolysis vapor in a two-stage fixed bed reactor

The pinewood was pyrolyzed in the first reactor at a heating rate of 10   °C   min −1 from room temperature to 700   °C, and the vapor was allowed to be cracked through the second reactor in a temperature range of 450–750   °C without and with HZSM-5. Attempts were made to determine a wide spectrum of gaseous and liquid products, as well as the mass and element partitions to gas, water, bio-oil, coke and char. HZSM-5 showed a preferential deoxygenation effect via the facilitated decarbonylation and decarboxylation with the inhibited dehydration at 550–600   °C. This catalyst also displayed a high selectivity for the formations of aromatic hydrocarbons and olefins by the promoted hydrogen transfer to these products at 550–600   °C. The bio-oil produced with HZSM-5 at 500–600   °C had the yields of 14.5–16.8%, the high heat values of 39.1–42.4   MJ   kg −1 , and the energy recoveries of 33–35% (all dry biomass basis).