Kinetics Study Of Ethylene Combustion Over A Cumno Hopcalite Catalyst

With the aid of a catalytic combustion process, the carbon dioxide stream fromethylene oxidation or ethylene glycol (EO/EG) process can be purified to reach thestandard of food grade carbon dioxide. The kinetics and kinetic model of the traceamount ethylene combustion in a carbon dioxide stream over a Cu-Mn-O mixed oxidecatalyst have been investigated in this work. The ethylene combustion mechanism isdiscussed. Effort has been made to improve the catalyst preparation and to optimizethe operating conditions of the combustion process.The Cu-Mn-O mixed oxide catalyst was prepared with a co-precipitation methodunder a sub-commercial scale. The preparation was done in a2000L stirring tankreactor with industrial grade reagents following the coprecipitation conditions setup inthe laboratory. The prepared catalytic material was shaped as extrudates for pilot test.The activity test in laboratory showed that the preparation repeated exactely theactivity value measured with the samples prepared in laboratory. The XRD and BETmeasurement results show also that the catalyst phase composition texture data arealso repeated well. The preparation scale-up and the extruding of the catalyst materialhave no adverse impact on the resulting catalyst.In order to understand the catalytic reaction mechanism, and to describe theinfluence of the reaction temperature, pressure and space velocity on the reaction rate,the intrinsic reaction kinetic model of the catalyst is investigated. The effect of theexternal and internal diffusions was excluded firstly. The Nelder-Mead simplexmethod was employed in the non-linear regress of the intrinsic kinetic experimentaldata. The Power Rate Law, and the Langmuir-Hinshelwood (LH), Eley-Rideal (ER)and Mars-van Krevelen (MVK) models were compared to obtained a most fit modelequation for the ethylene combustion reaction. Finally, with the help of the situDRIFTS technique, the catalytic reaction mechanism of trace amount ethylenecombustion over Cu-Mn-O catalyst is discussed.The activity and stability of the extruded catalyst were tested with an industrialside-stream. The experimental data were analysed. Combined with the intrinsickinetic research, the effectiveness factor of the extruded catalyst was calculated andthe condition of the commercial application in industry was predicted.