Carbon-Assisted, Continuous Syngas Production in a Chemical Looping Scheme

In the current energy and environment scenario, it is imperative to develop energy efficient routes for chemical manufacturing that also pave the way for mitigation of greenhouse gas emissions. This work presents an efficient pathway for continuous syngas production via a chemical looping conversion of the two most potent greenhouse gases—CH₄, and CO₂. The well-known dry-reforming process of converting CH₄, and CO₂ to syngas is energy-intensive and suffers from catalyst deactivation. The chemical looping approach, on the other hand, provides avenues for mitigating catalyst deactivation and enabling improved energy efficiency. The key to such process enhancements lies in the intricate structure–function relationships of the catalyst and its correlation to the process variables. We present the reduction and oxidation characteristics of 5 wt.% Ni/Ce_1−xZr _xO₂-based catalysts (x = 0, 0.4, and 0.625). We demonstrate low temperature CH₄ activation over Ni-promoted samples as opposed to pure Ce_1−xZr _xO₂. Moreover, our results depict an optimum regeneration of these catalysts when oxidized by CO₂, and H₂O, which allows for chemical looping operation of steam reforming of methane as well. Process variables were tuned to optimize the CH₄ conversion (over 80%), and H₂/CO ratio at 650 °C. The critical surface reactions—carbon accumulation and gasification, and thermocatalytic CO₂ splitting were investigated to elucidate the dynamic nature of the catalyst surface. The impact of this work lies in showcasing the opportunities to design chemical looping reactors for energy efficient syngas production from waste greenhouse gases.