Performance Evolution of Ethanol Carbonylation on Ni/Activated Carbon Catalyst
Ni-based catalysts supported by activated carbon(Ni/AC)have been observed to display good activity for the heterogeneous ethanol carbonylation reaction.However,it has also been demonstrated that Ni/AC catalysts are susceptible to deactivation during the reaction process.Therefore,it is crucial to gain insight into the deactivation mechanism and the rationale during the reaction process,with an aim to enhance the catalyst's stability.In this study,the Ni/AC catalyst was prepared using an impregnation method,and the catalysts with varying reaction times were characterized and analyzed.The findings demonstrated that the re-dispersion of Ni nanoparticles in the presence of co-catalyst ethane iodide led to an enhancement in the initial ethanol conversion.Conversely,the aggregation of Ni species resulted in a notable reduction in the ethanol conversion over the 10 to 30 h period.The amount of carbon species deposited on the catalyst rises in conjunction with the duration of the reaction,which consequently results in a reduction in the specific surface area and pore volume of the catalyst.It was further determined that the carbon deposited species may contain propionic acid,ethyl propionate,or intermediates containing propionyl.The deposition of carbon significantly impeded the CO adsorption of the catalyst,resulting in a reduction in the selectivity of propionic acid and ethyl propionate.Subsequent investigation revealed that a reduction in the proportion of ethyl iodide led to a notable decline in catalyst activity,accompanied by an enhancement in catalytic stability.
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