AIR: Towards a CO2-free, Sustainable, Ethylene Oxide Technology

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Conventional ethylene oxide (EO) processes emit CO2 as byproduct (roughly 3.4 MM tons/yr) from the combustion of both the ethylene and EO, the elimination of which has been a major grand challenge in industrial chemistry for decades. In a NSF-funded project, an alternate technology concept that is 99% selective toward EO was recently demonstrated at the University of Kansas with no detectable CO2 formation. This alternate process is based on homogeneous ethylene oxidation with H2O2 at 25-40C and ~50 bars using methyltrioxorhenium (MTO) as catalyst. This proposal addresses the key barrier to commercialization, viz., the design and demonstration of a recyclable MTO catalyst. Both heterogeneous supports and bulky soluble polymers (capable of retention in solution by nanofiltration membranes) are being considered. Quantitative catalyst performance metrics (activity, selectivity and durability) for practical viability have been established through preliminary economic analysis and will guide catalyst design. Successful completion of the project objectives will result in novel, recyclable catalyst formulations for epoxidation reactions in general. The demonstration of a continuous ethylene-expanded liquid phase catalytic reactor will be the first of its kind. The project guidance from ADM (interested in epoxidation of vegetable oils), Evonik (a major H2O2 producer) and P&G (a major EO consumer) personnel increases the probability of project success and eventual commercialization. The proposed concept has the potential to result in significant conservation of oil and gas reserves (~13 million barrels crude oil/year) and reduction of carbon emissions as byproduct (3.4 million metric tons of CO2 each year). The application of this technology to mixed feeds containing ethylene and ethane will also result in significant energy savings associated with their separation required in conventional processing. The technical outcomes from this proposed work will be integrated into an ongoing course titled Development of Sustainable Chemical Processes, impacting both the undergraduate and graduate curricula.