Simultaneous production of ethylene and hydrogen through carbon dioxide assisted conversion of ethane over cobalt-molybdenum catalysts

The necessities of hydrogen and olefins productions are motivations for exploring new and multipurpose processes. Moreover, a suitable strategy to control the emission of carbon dioxide is its utilization in the conversion of chemicals. Carbon-dioxide-assisted conversion of ethane to hydrogen and ethylene is a non-cracking route aimed to reduce the energy consumption and carbon dioxide emission, as well as to produce hydrogen, in the future petrochemical plants. Accordingly, carbon-dioxide-assisted conversion of ethane to ethylene and hydrogen over alumina-supported cobalt-molybdenum catalysts are examined in the present study. This method would decrease the undesired impacts of carbon dioxide release on the environment and also enhance the efficiency of ethane conversion to ethylene in terms of lower energy consumption and hydrogen production. The catalyst samples are characterized by X-ray diffraction and nitrogen adsorption/desorption methods. Moreover, sensitivity analysis experiments are conducted to determine the effects of temperature (600-700 °C) and reactant to catalyst ratio (2250-9000 Lreactant/kgcatalyst.hr) on the conversions of reactants as well as product yields. The highest initial conversions (88.4 % for ethane and 28.3 % for carbon dioxide) are observed at 700 °C and GHSV=2250 Lreactant/kgcatalyst.hr over a catalyst sample including 3.4 wt. % cobalt and 13.6 wt. % molybdenum. The highest initial hydrogen yield (59.10%) was also obtained in the same condition. The highest initial ethylene production (42.95 %) is observed in the case of 4.4 wt.% cobalt and 7.5 wt.% molybdenum at 700 °C and GHSV=9000 Lreactant/kgcatalyst.hr. The effect of time on stream is also determined to investigate the stability of catalyst samples. Slight changes in the conversions and products yields are observed indicating the stable performance of the catalysts in the studied reaction condition.