Catalytic calcium-looping gasification of biochar with in situ CO2 utilization with improved energy efficiency

Capture and conversion of CO 2 from optimal-scenarios into fuels or chemicals provide a viable solution to combat climate change in reducing greenhouse gas emissions. Here, we propose and experimentally demonstrate that synergistic integration (Catalytic calcium-looping (CaL) gasification of biochar) can realize the capture and in situ conversion of CO 2 . Thermodynamic and kinetic estimations, catalytic conversion and cyclic tests and microstructure characterizations showed that by using a mixture of limestone and K 2 CO 3 -impregnated biochar, calcination fully coupled with the reverse Boudouard reaction can shift thermodynamic equilibrium and simultaneously induce the synergetic catalysis between CaCO 3 and K 2 CO 3 , allowing for accelerating decarbonation kinetics, enhancing CO yield and maintaining stable cyclic CO 2 conversion at lower temperatures (850 °C), as compared to the individual CaL and gasification processes. Theoretical calculations further revealed that the activation energy barriers for the monatomic C-assisted CO 2 dissociation were lower than its desorption energy for CO 2 on the K-doped CaO surface, demonstrating superior conversion reactivity. Importantly, the process is demonstrated in terms of practical scalability using a renewable and cost-effective reductant (biochar), a cheap catalyst (K 2 CO 3 ) and inexpensive natural CO 2 sorbents (limestone and dolomite) in an energy-efficient manner, therefore opening a unique direction for net-negative emission for large CO 2 stationary sources eliminating the need for sequestration.