Optimizing KOH/cPVC Ratio for Improved CH<sub>4</sub> and CO<sub>2</sub> Adsorption Capacities of Porous Carbon Adsorbents

Abstract

As the global imperative to achieve net zero emissions has intensified, innovative technologies for hydrogen production have become critical. In this study, an advanced approach based on the use of chlorinated polyvinyl chloride (cPVC) activated with potassium hydroxide (KOH) was introduced to synthesize porous carbon adsorbents for enhanced capture of methane (CH4) and carbon dioxide (CO2). When the KOH/cPVC ratio and carbonization temperature were adjusted, the structural properties of the adsorbents were tailored to improve their performance significantly. Various analytical techniques were also employed, including scanning electron microscopy, X-ray diffraction, and adsorption isotherm measurements, to characterize the morphological and chemical properties of the synthesized adsorbents. The results revealed that under specific conditions, significant improvements in the CH4 and CO2 adsorption capacities were achieved, with the cPVCK1-800 sample reaching uptake values of 1.94 and 4.20 mmol/g, respectively, at 25 degrees C and 1 bar. These results underscore the utility of cPVC-derived porous carbon materials for environmental applications, thereby marking a significant advancement in materials for gas separation and storage. Moreover, density functional theory calculations were performed to elucidate the interactions of the oxygen functional groups within the adsorbents, which contributed to their superior performance. These theoretical insights complement the experimental findings and provide a comprehensive understanding of the behavior of these materials in various gas adsorption scenarios. Moreover, these findings suggest novel pathways for developing cost-effective and efficient adsorbents, thereby supporting global efforts toward achieving environmental sustainability.