Hydrogen storage behavior of zeolite/graphene, zeolite/multiwalled carbon nanotube and zeolite/green plum stones-based activated carbon composites

Abstract

In this study, novel zeolite/carbon composites were synthesized to determine hydrogen storage properties. Activated carbon (AC), graphene (GR) and multi-walled carbon nanotubes (MWCNT) were used as carbon sources in the preparation of the composites with faujasite type zeolite. AC was prepared from green plum stones by using ultrasound assisted chemical activation with the use of potassium hydroxide. In order to compare the textural and hydrogen storage properties of the prepared zeolite/activated carbon, zeolite/graphene and zeolite/multiwalled carbon nanotube composites were prepared from commercial GR and MWCNT, respectively. The structures of the obtained AC and composite samples were characterized using BET, DFT, t-plot and SEM-EDX techniques. AC was synthesized with a relatively high BET surface area (1694 m2/g), total pore volume (1.023 cm3/g) and micropore volume (0.780 cm3/g). Zeolite/activated carbon composite (ZAC) has the highest surface area, total pore volume and micropore volume, and zeolite/multiwalled carbon nanotube composite (ZNT) has the highest average pore width (6.64 nm) among all composite samples. Hydrogen sorption processes have been performed for composite samples at −196 °C and ambient pressure. The relationship between hydrogen sorption capacities, BET surface areas and pore volumes of ZAC, ZGR and ZNT composites have been investigated. The hydrogen storage capacity of the ZAC was found to be 1.3 wt%. This value is 1.47 times the hydrogen storage capacity of AC and 4.16 times the hydrogen storage capacity of zeolite. Results indicated that ZAC is a promising adsorbent for hydrogen storage.