Borealis to construct PDH plant for propylene production in Belgium

Abstract

The production of renewable propene from biomass-derived ethanol is highly significance for sustainable chemical production. Herein, propene was produced directly from bioethanol over ZnCeOx and HBeta composites. Although the basicity of ZnCeOx is necessary for the first step of ethanol dehydrogenation, catalyst acidity is much more crucial for propene selectivity. Si/Al ratio of HBeta and its ratio to ZnCeOx oxide were optimized to be 43 and 1:10, respectively. This hybrid catalyst gives an over 55 % yield of propene and only 3% yield of ethene under optimized conditions. NH3-TPD and 31P MAS NMR using trimethylphosphine oxide as a probe show that more weak Brönsted acid sites and relatively strong Lewis acid sites in composites significantly increase propene selectivity. Ethanol-TPD-MS, in situ DRIFTS and acetone model reaction suggest the possible reaction pathways could be ethanol→acetaldehyde→ethyl acetate→acetone→isopropanol→propene. The composite catalyst shows no obvious deactivation, propene selectivity remains around 50 % after three regeneration cycles.