2025-02-18 ミネソタ大学
This illustration depicts the combustion of small amounts of acetylene in mixtures with ethylene. Credit: Greg Stewart/SLAC National Accelerator Laboratory
＜関連情報＞
- https://cse.umn.edu/college/news/selective-combustion-provides-energy-efficient-alternative-remove-pollutants
- https://www.science.org/doi/10.1126/science.ads3181
エチレンリッチ流におけるアセチレンの選択的化学ループ燃焼 Selective chemical looping combustion of acetylene in ethylene-rich streams
Matthew Jacob, Huy Nguyen, Rishi Raj, Javier Garcia-Barriocanal, […], and Aditya Bhan
Science Published:13 Feb 2025
Editor’s summary
Trace acetylene can be removed from ethylene feedstocks by selective combustion of acetylene. Jacob et al. found that the lattice oxygen of bismuth oxide can combust acetylene with more than 99% selectivity for gas streams containing equimolar or dilute amounts acetylene in ethylene. Lattice oxygen removed by combustion could be regenerated over many cycles by reaction with molecular oxygen. This alternative purification route to semihydrogenation of acetylene does not require elevated pressures and is tolerant to carbon dioxide and water impurities. —Phil Szuromi
Abstract
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.
