Catalytic intermediate pyrolysis of post-extraction rapeseed meal by reusing ZSM-5 and Zeolite Y catalysts

This study describes an experimental investigation comparing the effects of two catalysts (ZSM-5 and Zeolite Y) on intermediate pyrolysis. The catalysts are characterized by different acidities, expressed by silica-to-alumina ratios of 352 (ZSM-5) and 26 (Zeolite Y). The post-extraction rapeseed meal was pyrolysed in a fixed-bed furnace at a temperature of 500 °C, and the pyrolysis products (char, liquid phase, and pyro-gas) were characterized in detail. The catalysts were assessed based on their reusage capability. Five-fold more carbon was deposited on Zeolite Y than on ZSM-5 after 10-fold use during the pyrolysis of rapeseed meal. Moreover, the ultimate analysis of the catalysts showed increases in the hydrogen and nitrogen contents, which were significantly higher for Zeolite Y than those for ZSM-5. The catalysts showed different effects on the properties of the products. Better-quality pyro-gas was obtained with Zeolite Y, but reusage of this catalyst resulted in decreases in the hydrogen and carbon oxide concentrations. Compared to Zeolite Y, ZSM-5 afforded bio-oil with a lower oxygen content. Phenols and ketones were dominant compounds in both bio-oils. Regeneration of Zeolite Y caused to increase of specific surface area.