Optimization for online catalytic upgrading of bio-oil from rape straw over MCM-22 zeolite

Abstract

ABSTRACTOnline vacuum catalytic upgrading of pyrolysis vapor from rape straw over MCM-22 zeolite was performed. The effects of catalytic temperature, catalytic bed height, and holding time on the yield of bio-oil organic phase were discussed. The response surface method was used to optimize the process parameters of the experiment. The composition and physicochemical properties of bio-oil organic phase were analyzed. The results showed that catalytic temperature and catalytic bed height had great influence on the yield of bio-oil organic phase, while holding time had little effect on the yield of bio-oil organic phase. The interaction between catalytic temperature and catalytic bed height was significant, but the interaction between catalytic temperature and holding time and the interaction between catalytic bed height and holding time were not significant. The optimal conditions for the maximum yield of bio-oil organic phase were obtained at catalytic temperature of 486.3°C, catalytic bed height of 1.82 cm, holding time of 42 min, and the maximum yield reached 17.53%. Compared with the bio-oil organic phase without catalytic reaction, the density, kinematic viscosity, oxygen content, and acid content of the refined bio-oil organic phase obtained under optimal conditions decreased, and the pH value, hydrocarbon content, and heating value increased. In addition, the refined bio-oil organic phase was mainly composed of C5–C9 compounds, and most of the compounds above C12 converted into small molecular compounds. The comprehensive quality of bio-oil was improved significantly after catalytic reaction.