Abstract:
With a focus on rice husk, this study explores the possibilities of supercritical water
gasification (SCWG) for the effective synthesis of hydrogen from biomass. Compared
to conventional fossil fuels, biomass is a possible substitute, and SCWG provides an
energy- and environmentally friendly method of producing hydrogen. The need to
maximize catalytic efficiency and reduce this process's environmental impact is what
motivates the study. The main focus is on Ni/eggshell catalysts, with the goal of filling
up important information gaps about catalytic activity, stability, and the generation of
clean hydrogen from biomass sources that are renewable. This research assesses the
performance of Ni/eggshell catalysts in biomass SCWG and seeks to establish the
suitable working conditions that would yield the highest levels of hydrogen with
negligible levels of by-products. The catalyst synthesized with three loadings (5 wt%,
10 wt%, and 20 wt%) in the production of hydrogen in SCW at three different
temperatures (370°C, 450°C, and 500°C) and two residence time (60 minutes and 80
minutes) Also, it reviews the Ni/eggshell catalysts in the aspects of activity, stability,
and impact on the environment in SCWG. Ni/eggshell proved to be very active in
SCWG of rice husk biomass especially with moderate loading of Ni, (10 wt% provided
adequate active sites with least chance of particle sintering). According to the
experiments, the best conditions for hydrogen production were the temperature 500°C;
the residence time of 80 minutes, and the catalyst loading of 10 wt%. These conditions
gave the highest gas yields and hydrogen content, and the least solid residues implied
that the biomass was almost fully converted. The SEM and XRD studies revealed that
there are no morphological changes, and the Ni particles were effectively dispersed and
uniformly distributed on the CaO support, thus the catalytic activity was constant.
According to the obtained FTIR and XRD results, the catalyst was stable in the course
of the reaction.
