Optimising Zeolite Synthesis for Efficient Carbon Capture and Conversion to Renewable Natural Gas

Abstract

The growing need for cleaner energy production has spurred the development of advanced materials capable of addressing environmental challenges. This has driven research into materials that can capture carbon dioxide while maintaining sustainability and cost-effectiveness. Zeolites, aluminosilicate materials synthesised from abundant elements, present a promising solution as dual-function materials (DFMs) for both CO₂ capture and conversion to renewable natural gas (RNG) via methanation. To understand how structural differences can affect CO₂ adsorption, this study investigates the synthesis and performance of three zeolite types: small (Chabazite, CHA), medium (MFI, ZSM-5), and large (Faujasite, FAU, Y-zeolite). Each was synthesised from scratch using silica and aluminium precursors, with fluoride and alkali promoters to facilitate framework formation. This encompassed a sequence of material addition, gel aging, crystallisation, and drying to produce the powder. Among these materials, the Y-zeolite was hypothesised as the optimal candidate due to its large pore structure—-providing the most abundant number of sites for CO₂ adsorption, assessed by exposing the materials to simulated air streams (400 ppm CO₂). Confirmed through X-ray Diffraction (XRD) and CO₂ Temperature-Programmed Desorption (TPD), Y-zeolite demonstrated high CO₂ adsorption capacity and structural stability across repeated cycles. However, CHA exhibited sensitivity to water, whereas ZSM-5 synthesis trials remained inconsistent, requiring further optimisation to be achievable in the laboratory. Future work will focus on refining synthesis procedures for repeatability, evaluating long-term performance under realistic conditions, and assessing candidacy for industrial scale-up. These findings propel zeolites as viable materials for power-to-gas (P2G) applications, contributing to carbon emission reduction measures.