Catalytic conversion of biomass-derived C1-C6 mixed alcohols to olefins: A comparison of HZSM-5, SAPO-34 and γ-Al2O3 catalysts

Biomass-derived C-1-C-6 mixed alcohols can be obtained by one-step conversion of biomass in supercritical methanol. However, the dehydration of these mixed alcohols to olefins, a valuable chemical feedstock, has not been well studied. Here we show that the composition and proportion of mixed alcohols affect the catalytic performance and product distribution of dehydration over three acidic catalysts (HZSM-5, SAPO-34 and gamma-Al2O3). We find that methanol and C-5-C-6 alcohol have negative effects on the catalytic dehydration of HZSM-5, SAPO-34, and gamma-Al2O3. We find that HZSM-5 is more selective for C-2-C-6 mixed alcohols, while SAPO-34 and gamma-Al2O3 are more suitable for C-2-C-4 mixed alcohols. We also demonstrate that removing methanol and C-5 -C-6 mixed alcohols from the feed stream can significantly improve the olefin selectivity over SAPO-34. Based on these results, we propose a dehydration conversion method for biomass-derived C-1-C-6 mixed alcohols, which involves separating methanol and C-5-C-6 mixed alcohols for recycling and catalyzing the remaining mixed al-cohols over gamma-Al2O3 (olefin selectivity 97.0%). This method provides a feasible and economical route for further utilization of biomass-derived mixed alcohols.