Computational Study of Metal-Organic Frameworks for CO2 Capture and Reduction

Abstract

The escalating levels of carbon dioxide in the Earth's atmosphere present one of the most crucial environmental challenges facing humanity today. Carbon dioxide acts as a heat-trapping agent, leading to an increase in global temperatures. The consequences of unbridled carbon dioxide emissions are vast and concerning, encompassing the potential for widespread devastation to ecosystems, loss of biodiversity, and significant economic and social upheaval. Hence, it is imperative that we undertake meaningful steps to curtail our carbon emissions and reduce the impact of this critical environmental issue. To this end, various technologies have been developed, including carbon dioxide capture and reduction. However, the state-of-the-art catalysts for both these technologies are often expensive and exhibit low selectivity. This thesis endeavors to identify alternative Metal Organic Framework based catalysts for both the capture and reduction of carbon dioxide. Metal Organic Frameworks present an excellent alternative due to their tunability. To assess the ability of the HCALF- 50 and CALF-50 MOFs for carbon dioxide capture, Molecular Dynamics Simulations were employed. It was discovered that both systems, especially CALF-50, were unstable due to temperature variations. Nonetheless, the use of template molecules allowed the systems to retain their configurations. Regrettably, neither system proved capable of capturing carbon dioxide, as determined by the diffusion of carbon dioxide between the pores of both systems. The Computation-Ready Experimental Metal-Organic Framework database was utilized to identify Metal Organic Frameworks for the reduction reaction. For this reaction, the focus was on the two-electron reaction since carbon monoxide is a precursor to the production of syngas. Three Zeolitic Imidazolate Frameworks, specifically ZIF-8, ZIF-70, and ZIF-82, were identified and studied using Density Functional Theory. It was determined that the newly identified ZIF-70 and ZIF-82 were not suitable candidates towards the production of carbon monoxide, and preferentially produced hydrogen gas. Consequently, the findings of this study indicate that HCALF-50 and CALF-50 are inadequate for capturing carbon dioxide, while two catalysts, ZIF-70 and ZIF-82, have been identified as unsuitable catalysts for the reduction reaction to carbon monoxide.