Catalytic fast pyrolysis of a wood-plastic composite with metal oxides as catalysts

The catalytic fast pyrolysis of a poplar wood-polypropylene composite (WPP) was investigated using Py-GC/MS in the presence of ZnO, CaO, Fe2O3 and MgO. The synergistic effects between wood and plastic components in both non-catalytic and ZnO-catalyzed pyrolysis of WPP were studied. CaO facilitated the removal of oxygen due to its strong basicity, eliminating carboxylic acids and phenols from the products, while slightly increasing cyclopentanones and alkenes. MgO has weaker deoxygenation but stronger chain scission activities versus CaO, and significantly enhanced the alkene yields. Alkene yields were highest using ZnO among the four catalysts. ZnO increased ketone and phenol yields while reducing carboxylic acids. Aromatics were identified in the presence of Fe2O3. A synergistic effect between poplar wood and PP in the uncatalyzed pyrolysis of WPP increased the yields of carboxylic acids, phenols and light alkenes, while it reduced carbonyl-containing oxygenates such as aldehydes, ketones and furans. The synergy in the ZnO-catalyzed pyrolysis of WPP further enhanced the formation of monomeric phenols and alkenes.