Modified kenaf via nickel nitrate for hydrogen gas storage

Abstract

Hydrogen is one of the renewable energy sources that are viable as an alternative fuel source. Hydrogen fuel offers protection towards the environment. Hence, hydrogen storage is a necessity in order for hydrogen fuels can be used for mobile purposes. However, one of the major barrier for hydrogen fuels is the storage technique. To prevent high pressure problem during storing, kenaf as adsorptive hydrogen storage was introduced in this study. Since kenaf is a natural adsorbent with porous structure, modification with nickel metal for hydrogen adsorption process was conducted. The objectives of the study were to characterize kenaf and modified kenaf as adsorbents, to assess adsorptive capacity of the adsorbents and to assess delivery performance of the adsorptive gas storage. In this study, nickel nitrate (Ni(NO3)2) was used to modify kenaf using nickel metal deposition method. The concentration of Ni(NO3)2 was varied for each sample to determine the suitable amount of modifier for the kenaf sample. The pressure applied during the experiment was also varied in order to observe the delivery performance of the hydrogen adsorption. The physisorption occurred between hydrogen molecules and kenaf samples showed that modified kenaf was capable to adsorb more hydrogen as the hydrogen molecules was trapped within metal surface and kenaf surface itself. From this study, kenaf with 0.4 M of nickel (Ken-0.4MNi) showed better result in adsorbing hydrogen compared to raw kenaf sample. The specific area measurement for this sample was 1.315 m2/g as it was a combination of mesoporous and macroporous structures. The field scanning electron microscopy micrograph of Ken-0.4MNi showed convincing surface structure for hydrogen molecules that had been adsorbed and stored since 0.4 M N-metal added improved the molecules arrangement in adsorbent. Based on the findings, Ken-0.4MNi could adsorbed 15.0 mmol/g hydrogen at pressure of 4 bar.