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Catalytic Oxidation of Ethane to Carboxylic Acids in the Liquid Phase at Near Room Temperature at Ambient Pressure
- Li, Yuting, Tang, Yu, Nguyen, Luan, Tao, Franklin Feng
- ACS sustainable chemistry & engineering 2018 v.7 no.5 pp. 4707-4715
- ambient pressure, ambient temperature, aqueous solutions, catalytic activity, chemical industry, energy industry, ethane, feedstocks, formic acid, fuels, hydrogen peroxide, liquids, micropores, oxidation, shale gas
- Chemical transformation of shale gas components under mild conditions is ideal for utilizing the shale gas resource to produce high-value intermediates of chemical industries and fuel feedstocks of energy industries. Here we report that single Rh atom sites, Rh₁O₅ anchored in micropores of HZSM-5, can catalyze oxidation of ethane by hydrogen peroxide in aqueous solution to form acetic acid and formic acid at a temperature ≤ 50 °C at a pressure of ethane at 1.5 bar. Conversion of 1.5 bar of ethane to carboxylic acids at 50 °C in a Parr rector reaches 37% within 2 h. Acetic acid and formic acid are formed through two parallel reaction pathways with apparent activation barriers of 32.5 and 35.5 kJ/mol in the temperature range of 50–72 °C, respectively. Turnover rates for forming carboxylic acids are 0.060 acetic acid molecules on each Rh₁O₅ site per second (216 mol of acetic acid per mol Rh per hour) and 0.127 formic acid molecules on each Rh₁O₅ site per second (457 mol of formic acid per mol of Rh per hour) at 50 °C. This study suggests a very promising catalytic process of synthesis of carboxylic acids at near room temperature at ambient pressure.