The stereochemistry of ethylene-1,2-d2 epoxidation over silver catalysts

摘要

The stereochemistry of the catalytic epoxidation of cis-ethylene-1,2-d2 to ethylene oxide over four unsupported and two supported silver catalysts as well as over Ag2O and AgO was studied. Variations of the stereochemistry with reaction composition including addition of C4H2Cl2 to moderate the catalyst and the use of N2O as the oxidant were also explored. Equilibration in the product ranged between 57 and 99%. A correlation in the equilibration with extent of oxidation of the surface was proposed. Several models were discussed which could rationalize the observed partial equilibration and the sensitivity of the randomization kinetics to certain reaction variables such as oxygen concentration or addition of C2H4Cl2 or N2O but not others such as temperature and catalyst selectivity.