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

Abstract

Biomass-derived C1-C6 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 γ-Al2O3). We find that methanol and C5-C6 alcohol have negative effects on the catalytic dehydration of HZSM-5, SAPO-34, and γ-Al2O3. We find that HZSM-5 is more selective for C2-C6 mixed alcohols, while SAPO-34 and γ-Al2O3 are more suitable for C2-C4 mixed alcohols. We also demonstrate that removing methanol and C5-C6 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 C1-C6 mixed alcohols, which involves separating methanol and C5-C6 mixed alcohols for recycling and catalyzing the remaining mixed alcohols over γ-Al2O3 (olefin selectivity 97.0%). This method provides a feasible and economical route for further utilization of biomass-derived mixed alcohols.