Glycerol hydro-deoxygenation aided by in situ H2 generation via methanol aqueous phase reforming over a Cu–ZnO–Al2O3 catalyst?

Catalysis Science & Technology Pub Date: 2016-03-16 DOI: 10.1039/C6CY00132G

Abstract

A tandem catalytic cycle of methanol aqueous phase reforming–glycerol hydro-deoxygenation targeted to 1,2-propanediol formation under inert conditions is investigated. The H2 needed for glycerol hydro-deoxygenation is provided in situ via methanol reforming. The effects of reaction time, temperature, methanol concentration and system pressure were investigated over a Cu?:?Zn?:?Al bulk catalyst. The catalytic results showed that 1,2-propanediol selectivity and yield depend on reaction temperature and reaction time combination. Higher methanol concentrations favor glycerol hydro-deoxygenation towards the desired pathway, resulting in a significant increase in 1,2-propanediol selectivity. Under optimum reaction conditions (t = 1 h, T = 250 °C, 36 v/v% CMeOH + 9 v/v% CGLY, 1.0 < PN2 < 3.5 MPa), glycerol was almost fully converted (95.9%), with 79.4% selectivity (76.2% maximum yield) to 1,2-propanediol. Upon catalyst reuse, the Cu?:?Zn?:?Al catalyst showed satisfactory stability. An initial loss of activity (35.8%) was observed, which was ascribed to Cu agglomeration; however, catalyst performance was improved and stabilized after the third run, possibly due to Cu re-dispersion. It is proposed that metallic Cu0 efficiently catalyzes glycerol hydro-deoxygenation, while methanol reforming is mainly catalyzed by metallic Cu0 and facilitated by the interaction of Cu0 with ZnO–Al2O3 structures.

Graphical abstract: Glycerol hydro-deoxygenation aided by in situ H2 generation via methanol aqueous phase reforming over a Cu–ZnO–Al2O3 catalyst
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