Study On Copper-Based Catalysts For Hydrogenation Of Methyl Acetate To Ethanol

As a widely used organic chemical and fuel,the global demand for ethanol has increased sharply in recent years,and research and improvement of ethanol production processes need to be on the agenda.Among the many ethanol production routes,methyl acetate（MA）hydrogenation to ethanol（Et OH）stands out due to the high process economics,mild reaction conditions,and high selectivity of target products,will be the most promising ethanol production process technology in the future.The core of the process of hydrogenation of methyl acetate to ethanol is the preparation and development of catalysts.The work focuses on the improvement of the conversion of methyl acetate and the selectivity of ethanol.The reaction of hydrogenation of methyl acetate to ethanol has been analyzed by thermodynamics,including the factors affecting the heat of reaction and adiabatic temperature rise,the effects of reaction conditions on the conversion of MA and the selectivity of main and by-products.It provides theoretical guidance for the reaction from the perspective of thermodynamics.The effects of the preparation method on the hydrogenation performance of the catalysts have been investigated,evaluated and compared,the modified catalysts and the reaction conditions for the catalytic conversion of methyl acetate to ethanol have been studied.The research results of this paper are as follows.（1）Through thermodynamic simulation of the hydrogenation reaction of MA,it is found that at low temperature,high pressure,and high hydrogen to ester ratio is favorable for the reaction of MA hydrogenation to ethanol thermodynamically,while the conversion of MA and the selectivity of ethanol are high,and the main side reaction transesterification is suppressed.（2）Evaluation of the hydrogenation reaction of the catalysts prepared by the hydrothermal synthesis method,the impregnation method,and the co-precipitation method.In contrast,the co-precipitation method was found to be a more suitable method for preparing copper-based catalysts.The catalyst Cu-01 has excellent catalytic performance,the conversion of MA and the selectivity of ethanol on the catalyst Cu-01is high.In-depth studies have found that the main factors affecting the selectivity of ethanol are the basicity of the catalyst and the Cu⁰ content in the catalyst.A certain basicity of the catalyst is good for the selectivity of ethanol,while a large amount of Cu⁰promotes the reaction of methyl acetate and ethanol is not good for the selectivity of ethanol.The main factors affecting the conversion of MA are the Cu O crystal phase and the valence state of the copper after reduction.The good Cu O crystal phase structure is a prerequisite for the high conversion of MA.On this basis,the coexistence of Cu⁺and Cu⁰after catalyst reduction is a necessary condition for high conversion of MA.（3）The evaluation of the Cu-01 catalyst promoted by the barium compound shows that the addition of the barium compound can effectively improve the conversion of MA and the selectivity of ethanol.Ba（OH）₂ modified catalyst Cu-01 is more suitable for high reaction temperature,while Ba（NO₃）₂ modified catalyst Cu-01 is for low reaction temperature.In practical applications,the Ba（OH）₂ modified catalyst and the Ba（NO₃）₂modified catalyst can be used in combination to adapt to various reaction temperature conditions and obtain better catalytic performance.（4）The result of hydrogenation of MA to ethanol under different reaction conditions indicate that the suitable reaction temperature is 240°C-260℃,the reaction pressure is1.5 MPa-2.5 MPa,and the hydrogen to ester ratio is 30-50.