Catalytic co-conversion of glycerol and oleic acid to bio-aromatics: Catalyst deactivation studies for a technical H-ZSM-5/Al₂O₃ catalyst

The catalytic co-conversion of glycerol and oleic acid (45/55 wt%) to bio-based aromatics (benzene, toluene, and xylenes, bio-BTX) over a technical H-ZSM-5/Al₂O₃ catalyst in a fixed-bed reactor was investigated with special attention to catalyst deactivation phenomena. The spent catalysts after a time on stream (TOS) of 12 h were regenerated by an ex-situ oxidative treatment to remove coke and reused for another run. In total, 5 reaction-regeneration cycles were performed. The performance and characteristics of the fresh and regenerated catalysts were determined to identify and quantify the effects of co-feeding on catalyst stability and regenerability. The performance of the catalyst changes upon the number of reaction-regeneration cycles. Despite a negative effect on the peak BTX yield, a remarkable improvement in catalyst stability was found, leading to higher BTX productivity (1260–1505 g_BTX g_cat^-1 for the regenerated catalysts during a TOS of 12 h vs. 834 g_BTX g_cat^-1 for the fresh one during a life-time of 11 h). Detailed catalyst characterization studies show irreversible changes in the catalyst structure after reaction-regeneration cycle(s), such as textural property, crystal structure, framework, and acidity, which impact catalyst performance.