The
harmful impact on the environment due to SO
x
emissions from fuels and increasingly strict norms over the
years have amplified deep-desulfurization challenges, consequently
enhancing attractiveness of adsorptive separations. The present work
focuses on investigating metal modifications and process intensification
using acoustic cavitation for improving sulfur removal behavior and
selectivity. The proof of concept was elucidated using two model adsorbents:
one commercial Shirasagi TAC adsorbent and another newer adsorbent
derived from Cassia fistula biomass. Single- and
double-metal modifications were studied using zinc, cobalt, nickel,
and copper. An attempt was made to further improve the sulfur removal
using process intensification using acoustic cavitation coupled with
adsorption. The removal of three refractory sulfur compounds (viz.
thiophene, benzothiophene, and dibenzothiophene) was studied, and
the performance was compared for both single- and double-metal modifications
apart from process intensification. In the case of TAC, a high capacity
for sulfur removal, up to 23 mg S/g, was obtained, especially for
dibenzothiophene. Process intensification using cavitation coupled
with adsorption further improved sulfur removal to the extent of 100%,
and for metal-modified TAC, a capacity increase up to 38 mg S/g for
dibenzothiophene was obtained. The results indicate that the combined
effect of metal modification and process intensification can substantially
improve the sulfur-removal efficiency of carbon adsorbents.