Selective chemical looping combustion of acetylene in ethylene-rich streams
Matthew Jacob, Huy Nguyen, Rishi Raj, Javier García‐Barriocanal, Jiyun Hong, Jorge E. Perez-Aguilar, Adam S. Hoffman, K. Andre Mkhoyan, Simon R. Bare, Matthew Neurock, Aditya Bhan
Abstract
The requirement for C 2 H 2 concentrations below 2 parts per million (ppm) in gas streams for C 2 H 4 polymerization necessitates its semihydrogenation to C 2 H 4 . We demonstrate selective chemical looping combustion of C 2 H 2 in C 2 H 4 -rich streams by Bi 2 O 3 as an alternative catalytic pathway to reduce C 2 H 2 concentration below 2 ppm. Bi 2 O 3 combusts C 2 H 2 with a first-order rate constant that is 3000 times greater than the rate constant for C 2 H 4 combustion. In successive redox cycles, the lattice O of Bi 2 O 3 can be fully replenished without discernible changes in local Bi coordination or C 2 H 2 combustion selectivity. Heterolytic activation of C–H bonds across Bi–O sites and the higher acidity of C 2 H 2 results in lower barriers for C 2 H 2 activation than C 2 H 4 , enabling selective catalytic hydrocarbon combustion leveraging differences in molecular deprotonation energies.