Oxidation Of Ethylene In Microreactors

This work focuses on the research of microreactor, a innovational field. Anoumenal catalyst microreactor was made by silver metal and a capillary microreactorwas made by quartz capillaries successively, and the oxidation of ethylene toepoxyethane has been experimented in both microreactors. The properties ofmicroreactors and characters of oxidation of ethylene in microreactors have beeninspected.This work proves the feasibility of manufactured micrometer channels by drillingin silver metal. Though the experiments of oxidation of ethylene to epoxyethane hasbeen failed in it, the further exploration of manufacturing capillary microreactor bycoating α-Al₂O₃ carrier on quartz capillaries and loading silver catalyst on it hassucceeded. The experiments prove as follows: both the conversion of ethylene and theselectivity of epoxyethane in the oxidation of ethylene to epoxyethane happening inthe capillary microreactor without any catalysts promoter and inhibitors are higherthan the standard of industrialization, the highest selectivity is 82% and the highestyield of ethylene oxide is 57%;the space velocity of capillary microreactor evenreaches 5000h^-1, which exceed far away the standard of industrilization and may bepromoted still when the conversation of ethylene and the selectivity of epoxyethaneare quite balanced;the space-time yield of capillary microreactor is lower than theindustrial reactor because of the different operation condition, but it has greatpotential to be promoted;in addition the temperature of capillary microreactor can beeasily controlled, the safety are high, the chemical reaction can be conducted safelyduring the explosive scope of the mixing raw gas. Further analysis suggest that theflow type in the microchannels of microreactor is laminar flow, the specific surfacearea for heat transfer is large and the capability of heat transfer is great., the effect ofmass transfer are so good that flow in the microchannels can be mixed completelyduring millimeter seconds, and microreactor can be viewed as ideal plug flow reactor.The processes of chemical catalytic reactions in microreactors differ from traditionalfixed-bed reactor, because the velocities of internal diffusion and external diffusion inmicroreactors are very high, chemical reactions in microreactors usually are kineticcontrol reaction processes. Therefore microreactors are in the ascendant when they areused to determine the intrinsic kinetic equations of chemical reactions, of course theycan be used to develop and evaluate catalysis. Microreactors are more suitable forchemical reactions with high intrinsic reaction rates, because they can overcome therestrict of internal diffusion and external diffusion and promote the chemical reactionsrates.Finally as each coin has two sides, microreactors are not the panaceas for theproblem of conversion and selectivity in all chemical reactions processes, they areinevitably confined to certain areas. So combined with the work done an expectationhas been centered on the task and the direction of microreactor research. How torealize microreactors and how to apply them to suitable chemical reaction system arestill the primary task of microreactor research and designing catalyst in the process ofmanufacturing microreactors remains both the core point and difficulty inmicroreactor research.