Most efforts to chemically convert CO2 requires the use of H2, which is not desirable because at present the majority of H2 is generated from fuel cells, producing CO2 as a byproduct. How to find better alternatives to replace H2 for CO2 reduction remains a technical challenge. Shale gas primarily consists of methane, but also contains underutilized ethane (∼10% depending on the particular source). Recent efforts in converting CO2 by light alkanes, such as ethane, via the dry reforming pathway to produce synthesis gas (C2H6 + 2CO2 → 4CO + 3H2) paves a new direction for CO2 conversion. Compared with dry reforming of methane and CO2 which usually requires very high temperatures, ethane and CO2 dry reforming is thermodynamically favorable at lower temperatures. This makes it possible to separate methane and ethane in shale gas through dry reforming with CO2, by use of their differences in reaction temperatures, making it possible to produce synthesis gas from ethane and CO2, and leaving methane unreacted in shale gas. In this study, I will talk about CO2 photothermal conversion by light alkanes, with a focus on photocatalytic dry reforming of ethane and CO2, which presents a promising reaction pathway to make use of the abundant solar energy. I will begin from the basic thermodynamics for CO2 conversion by ethane, then summarize the recent effort in photocatalyst design, followed by a discussion of integrating an upscaled photothermal catalytic reactor platform coupled with photocatalyst for this reaction. The combination of vastly underutilized waste CO2 and underutilized ethane in shale gas to transform CO2 back to fuels creates a compelling challenge and exciting opportunity. This will shift the current practice of CO2 reduction by H2 to conversion by light alkanes, under solar irradiation.

Overview and outlook on CO2 photothermal conversion by light alkanes

2019 Spring National Meeting

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