Main content area

Synthesis, characterization and modification of monolithic ZSM-5 from geopolymer for CO2 capture: Experiments and DFT calculations

Chen, Hao, Zhang, Yao Jun, He, Pan Yang, Li, Chan Juan
Energy 2019 v.179 pp. 422-430
adsorption, binding agents, carbon dioxide, condensation reactions, cost effectiveness, crystallization, density functional theory, energy, industrial wastes, ion exchange, nickel, polymers, powders, silica, sodium, value added, zeolites
Zeolites exhibit the highest performance metrics among the second generation of post-combustion CO2 capture materials; however, conventional synthetic zeolite powders are relatively expensive and need to be shaped by binding agents for end use. In this study, cost-effective monolithic Na/ZSM-5 was successfully prepared for the first time using metakaolin and industrial silica fume waste as starting materials via polycondensation and seed-induced hydrothermal crystallization. The synthesised Na/ZSM-5 exhibited an adsorption capacity of 1.79 mmol/g CO2. To further enhance the CO2 adsorption capacity, the Ni/ZSM-5 was modified by ion-exchange of Na+ with Ni2+, revealing an improved adsorption capacity of 2.38 mmol/g CO2. Density functional theory (DFT) calculations were employed to explain the adsorption mechanism and the superior CO2 adsorption performance of Ni/ZSM-5 compared to Na/ZSM-5. The results show that the sorption of CO2 in both Na/ZSM-5 and Ni/ZSM-5 is physisorption by ion–dipole interaction, and the energy emission using Ni/ZSM-5 is higher than that using Na/ZSM-5 for the same CO2 capture efficiency. This research demonstrates a new method of preparing cost-effective shape-controllable zeolites with excellent CO2 capture capacity. Furthermore, it enables the high value-added utilization of the industrial waste of silica fume.