Introducing mesoporosity in zeolite 4A bodies for Rapid CO2capture

Abstract

In this study, we introduced mesoporosity by post-synthesis modification of binder-containing zeolite 4A (Z4A) bodies using urea treatment, to synthesize hierarchical zeolite 4A (HZ4A) with tailored textural properties. Hierarchical zeolite 4A such as HZ4A-1-3, HZ4A-1-1, and HZ4A-3-1 were synthesized by varying the urea to zeolite weight ratio as 1:3, 1:1, and 3:1 respectively. The synthesized HZ4A displayed tunable physicochemical characteristics, where HZ4A-1-3 exhibited improved surface area (126m2g-1), enhanced mesopore volume (0.44cm3g-1) and co-existence of both micro (ca. 0.4nm) and mesopores (5.5nm). HZ4A-1-3 also exhibited enhanced CO2 adsorption performance even when exposed to moisture at 1bar and 40°C. Moreover, HZ4A-1-3 displayed excellent CO2 adsorption stability over ten consecutive adsorption-desorption cycles. The presence of mesopores in HZ4A-1-3 facilitated rapid gas diffusion within the pores during both adsorption (29s faster) and desorption (92s faster), low water adsorption capacity (20 % lesser), mild desorption temperature (13°C lesser) and low CO2 heat of adsorption (14 % lesser) as compared to Z4A bodies, and hence achieved better CO2 adsorption efficacy for HZ4A-1-3 with reasonable CO2 regeneration energy. These results suggested the potential of hierarchical zeolite 4A (HZ4A) as a cost-effective sorbent for post-combustion CO2 capture application. © 2020 Elsevier Ltd.