CO2 Reduction and Syngas Production From CO2 and H2O Over Zn Particles In a Packed-Bed Reactor

A two-step solar thermochemical cycle for splitting CO₂ and mixtures of CO₂ and H₂O with Zn/ZnO redox reactions is considered, encompassing: 1) the thermolysis of ZnO with concentrated solar radiation as the heat source; and 2) the non-solar, reduction of CO₂ to CO or mixtures of CO₂ and H₂O to synthesis gas by oxidizing Zn to ZnO; the latter is recycled to the first step, and the resulting synthesis gas is the precursor for producing liquid hydrocarbon fuels from Fischer-Tropsch or other catalytic processes. The second step of the cycle is investigated using a packed-bed reactor where micron-sized Zn particles were immobilized in mixtures with submicron-sized ZnO particles. Experimentation over a range of CO₂-Ar and CO₂-H₂O concentrations was performed at different Zn/ZnO mass fractions. Mixing Zn and ZnO particles in the packed-bed significantly increased Zn-to-ZnO conversions compared with reactions with only Zn particles, where sintering reduced the active surface area needed for the reaction to proceed.