Tandem distributing Ni into CaO framework for isothermal integration of CO2 capture and conversion

Calcium Looping Dry Reforming of Methane (CaLDRM) could realize CO2 capture and in-situ valorization into syngas. The key to its success is the availability of a high-performance Ni-CaO based bifunctional material. The addition of promoters generally increases the material performance, but so does the material cost. Here, we tandem distribute Ni in CaO framework for material improvement, thereby lowering the reliance on promoters. Pre-doping of a trace amount of Ni into CaO matrix yields a mesopore-rich CO2 sorbent, which serves as an advantageous support to introduce the major Ni component via impregnation, resulting in highly dispersed active catalytic sites on the sorbent. Results demonstrate that the tandem Ni-CaO bifunctional material (Ni/NiCa) significantly outperforms the ordinary-one (Ni/Ca, without Ni pre-doping) in cyclic CO2 capture-conversion capacity and structural stability. After 10 cycles of isothermal CaLDRM at 650 degrees C, Ni/NiCa holds about 38 % higher CO2 uptake, 35 % higher CO2 and CH4 conversions as well as better resistance to particle sintering, carbon deposition and Ni oxidation than Ni/Ca. This work provides new insights into the design of low-cost "capture -catalytic" bifunctional materials aided by rational active component distribution.