Highly Active Heterogeneous Catalysts for Carbon Dioxide Reduction to Value-Added Chemicals
- Author(s): Kim, Sunkyu
- Advisor(s): Sasmaz, Erdem
- et al.
Carbon dioxide (CO2) utilization is indispensable to reduce high atmospheric CO2 concentration, attributing to global warming and ocean acidification. Reduction of CO2 into high value-added chemicals and fuels is a promising process to mitigate CO2 emissions and opens possibilities to have carbon-based energy production with net-zero carbon emissions. CO2 is the most oxidized form of carbon and thermodynamically stable. To effectively reduce CO2, nanotubular yolk–shell catalysts for methane reforming, and tandem catalysts for direct CO2 hydrogenation to light olefins were developed. In the former process, Ni yolks encapsulated with SiO2 shell demonstrated excellent stability with a high resistance to carbon deposition in the confined morphology due to the efficient CO desorption. Forming Pt–Ni single-atom alloys on the yolks pushed the catalyst operating temperature down to 500 °C and further improved the catalyst stability due to the enhanced Ni reducibility. In the latter process, indium oxide supported on zirconia and SAPO-34 zeolite were operated as a tandem catalyst to produce a high light olefins selectivity by shifting the reaction equilibrium to the right for the CO2 to methanol conversion. Zirconia promoted with yttria (YSZ) inhibited the reduction and hydroxylation of active indium sites. The improved oxygen vacancy formation in YSZ and strong metal–support interaction between indium oxide and YSZ resulted in stable light olefins production. These discoveries can be adopted to the current power generation and manufacturing processes to utilize CO2 emissions to produce high value-added chemicals with net-zero carbon emissions.