Production and characterization of bio-oil from catalytic fast pyrolysis of greenhouse vegetables wastes

Greenhouse vegetables produce high amounts of wastes which need to be addressed for efficient life cycle of raw materials and may cause environmental pollution if managed improperly. In this study, the effects of three parameters (pyrolysis temperature, catalyst type, and catalyst amount) on the distribution of products and quality of bio-oil obtained from fast pyrolysis of the mixture of greenhouse vegetables wastes (GVW) such as tomato, pepper, and eggplant were investigated. Fast pyrolysis experiments were carried out in a drop-tube-reactor system by using four different catalysts such as cerium oxide (CeO2), zinc oxide (ZnO), zirconium oxide (ZrO2), and Lewis acid (50% FeCl3 + 50% Na2SO4) with the amounts of catalysts as 4, 7, and 10 g and pyrolysis temperatures of 450, 500, and 550 degrees C. Bio-oil samples were characterized by elemental and GC-MS analyses. The use of different catalysts affected the products distribution and bio-oil chemical composition. Biochar yield increased with a relatively low pyrolysis reaction temperature, whereas the gas yield increased with temperature and catalyst amount. The bio-oil yield varied with catalyst type, but pyrolysis temperature and amount of catalyst had no significant effect. The bio-oil yield increased during catalytic fast pyrolysis (CFP) and the average maximum bio-oil yield of 45.4% was obtained during Lewis acid application. The lowest and highest bio-oil yields of 36.67% and 46.93% were obtained during the applications of 7g ZnO and 10 g Lewis acid at 450 degrees C, respectively. Chemical groups such as acids, furans, ketones, phenols, hydrocarbons, and benzene were abundant in the bio-oil samples obtained from CFP of GVW. Therefore, GVW is a promising feedstock to produce biofuels and useful chemicals through fast pyrolysis.