Selective chemical looping combustion of acetylene in ethylene-rich streams

The requirement for C2H2 concentrations below 2 parts per million (ppm) in gas streams for C2H4 polymerization necessitates its semihydrogenation to C2H4. We demonstrate selective chemical looping combustion of C2H2 in C2H4-rich streams by Bi2O3 as an alternative catalytic pathway to reduce C2H2 concentration below 2 ppm. Bi2O3 combusts C2H2 with a first-order rate constant that is 3000 times greater than the rate constant for C2H4 combustion. In successive redox cycles, the lattice O of Bi2O3 can be fully replenished without discernible changes in local Bi coordination or C2H2 combustion selectivity. Heterolytic activation of C-H bonds across Bi-O sites and the higher acidity of C2H2 results in lower barriers for C2H2 activation than C2H4, enabling selective catalytic hydrocarbon combustion leveraging differences in molecular deprotonation energies.