Study on K-modified Ca-based dual-functional materials for carbon capture and in-situ methane dry reforming

Abstract

Integrated carbon capture and in-situ methane dry reforming (ICCU-DRM) is a promising technology for chemical looping transformation, this process involves the sequential switching of feedstocks within a single reactor, allowing CO2 capture to occur before methane dry reforming without direct CO2-CH4 contact. However, a significant challenge in the ICCU-DRM process is the disparity between the optimal temperatures required for carbon capture and dry reforming, with the latter necessitating considerably higher temperatures. This could lead to substantial CO2 losses when the reaction temperature is elevated to the optimal level for dry reforming. To address this issue and improve CO2 conversion efficiency, this study explores K doping in synthesizing a dual-functional material, NiCa1.6K0.4@Al2O3, through extrusion-spheronization. The synthesized material exhibits a stable pore structure and a large internal surface area, crucial for enhancing CO2 capture. The optimum temperature for DRM is around 800 °C. Notably, the formation of 1K2Ca(CO3)2 during the calcination of NiCa1.6K0.4@Al2O3, with a thermal decomposition temperature of approximately 800°C, plays a crucial role in minimizing CO2 release during the heating process, thereby significantly improving the CO2 conversion. To evaluate the impact of K doping on the material, the samples were subjected to carbon capture at 650 °C and dry reforming of methane at 750 °C. The results showed that the CO2 conversion rate of NiCa1.6K0.4@Al2O3 reached 52.8%, compared to only 18.9% for NiCa2@Al2O3 under the same conditions. Moreover, this study also investigates the impact of carbon capture temperature, dry reforming temperature, and catalytic metal loading on the performance of the ICCU-DRM process.