As shale oil deposits continue to yield large amounts of light paraffins, technologies to convert waste feedstocks, such as ethane, are important in order to minimize flaring that leads to large amounts of carbon dioxide. Ethane can be directly converted to ethylene, which has a market need of 150 million tons/year. Standard operating reaction conditions for obtaining ethylene often require enormous amounts of energy with operating temperatures higher than 900°C. Low temperature oxidative dehydrogenation not only operates at temperatures of 500°C or lower, but uses oxygen as a co-reagent to switch the reaction from endothermic to exothermic. Nickel based catalysts have shown great promise at low temperatures for conversion. These catalysts have sensitive oxygen density vacancies and the nonstoichiometric nickel oxide concentrations that determine the selectivity of the ethylene compared to over-oxidation of ethane. We template nickel oxide catalysts using metal organic frameworks (MOF) to tune the nonstoichiometric oxygen density through the decomposition atmospheres to obtain optimized yields of ethylene. In this study, we report the optimization of MOF-derived Ni-oxide catalysts through i) decomposition atmospheres and ii) dopants and additives which change the selectivity and conversion of the reaction. Accepted conversion rates for ethane to ethylene are 1 kg ethylene/kg catalyst-hour. We aim to improve this conversion rate by optimizing the nickel-based catalyst and finding new pathways for decreasing energy costs for the reaction. We also present how MOF-derived catalysts can be a new approach for obtaining tuned oxidation states and nanoparticle sizes for metal oxide catalysts used in waste-feedstock conversions.

Catalytic conversion of ethane using a metal-organic-framework templated Ni-catalyst

ACS Spring 2022

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