Preparation Of Ethanol Dehydrogenation Cu-based Catalyst And Study The Shaping Process Of Supports

To meet the increased demand for acetaldehyde,the direct dehydrogenation of biomass ethanol into acetaldehyde has been developed,which is alternative green development due to the co-production of hydrogen,high atom economy,and easy separation of products.Ethanol molecule is relatively active and usually undergoes side reactions such as dehydration and aldol condensation,resulting in a decreased selectivity toward acetaldehyde.Cu-based catalysts can selectively dissociate the C-H bond of ethanol and are highly effective for the direct ethanol dehydrogenation.However,Cu-based catalyst supported by common oxides or porous carbon materials usually suffer from the low acetaldehyde selectivity and deactivation,calling for further optimizing.Based on our previous research on h-BN,by controlling surface defect sites and anchoring Cu species,a highly dispersed Cu-based catalyst was prepared,which can avoid secondary side reactions and inhibit Cu agglomeration,achieving high acetaldehyde selectivity and high stability.Firstly,a highly dispersed Cu-based catalyst was prepared by using the ball-milled h-BN as support and the relationship between catalyst structure and catalytic performance of ethanol dehydrogenation was figured out;secondly,the h-BN honeycomb molding process was investigated for the fabrication of monolithic ethanol dehydrogenation catalysts.The detailed research contents are as following:（1）The ball-milled commercial h-BN powder are rich in oxygen species（B-OH）on the defect edge sites,which play the key role in stabilizing Cu through the formation of B-O-Cu more than bringing side reactions.The catalyst exhibit an exceptional high acetaldehyde productivity of 7.33 g _{Ac H}/(g_cat×h)and acetaldehyde selectivity of～98%under high weight hourly space velocity of 9.6 g _{Ac H}/(g_cat×h)with a long lifetime over 50 hours.Cu species are still in near atomically dispersion over the BNS support for 5Cu/BNS catalyst.（2）The influence of process conditions such as binder type,gouacine ratio and calcination temperature on h-BN honeycomb molding were investigated.The synthesized h-BN honeycomb with the optimized process conditions achieves a water absorption of about 30%and a high compressive strength above 1.6 MPa.The honeycomb h-BN supported Cu catalyst exhibits excellent catalytic performance for ethanol dehydrogenation.