Photocatalytic Semi-Hydrogenation of Acetylene to Polymer-Grade Ethylene with Molecular and Metal-Organic Framework Cobaloximes.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39439160.
- Also identified by DOI 10.1002/adma.202408658 and PMC identifier 11707558.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The semi-hydrogenation of acetylene in ethylene-rich gas streams is a high-priority industrial chemical reaction for producing polymer-grade ethylene. Traditional thermocatalytic routes for acetylene reduction to ethylene, despite progress, still require high temperatures and high H<sub>2</sub> consumption, possess relatively low selectivity, and use a noble metal catalyst. Light-powered strategies are starting to emerge, given that they have the potential to use directly the abundant and sustainable solar irradiation, but are ineffective. Here an efficient, >99.9% selective, visible-light powered, catalytic conversion of acetylene to ethylene is reported. The catalyst is a homogeneous molecular cobaloxime that operates in tandem with a photosensitizer at room temperature and bypasses the use of non-environmentally friendly and flammable H<sub>2</sub> gas feed. The reaction proceeds through a cobalt-hydride intermediate with ≈100% conversion of acetylene under competitive (ethylene co-feed) conditions after only 50 min, and with no evolution of H<sub>2</sub> or over-hydrogenation to ethane. The cobaloxime is further incorporated as a linker in a metal-organic framework; the result is a heterogeneous catalyst for the conversion of acetylene under competitive (ethylene co-feed) conditions that can be recycled up to six times and remains catalytically active for 48 h, before significant loss of performance is observed.