Saba Iqbal, Hina Murtaza, Shahid Nazir, Fiaz Hussaın, Sadaf Ul Hassan
The growing demand for cleaner fuels and stricter regulatory limits on sulfur emissions globally has increased the demand for sustainable desulfurization strategies and processes. Although conventional hydrodesulfurization (HDS) is still the industrial standard, it requires high energy and hydrogen, and is not favorable for removing refractory sulfur-containing compounds, such as 4,6-dimethyldibenzothiophene. Other desulfurization approaches involve oxidative desulfurization (ODS) and adsorptive desulfurization (ADS), which also facilitate desulfurization at milder conditions, but also require a durable and active catalyst. Lignin, a renewable biopolymer obtained from pulping and agro-industrial waste, possesses diverse functional groups that make it a promising precursor and support for catalytic materials. This review critically examines the fundamentals of fuel desulfurization and compares conventional catalyst supports with emerging lignin-derived catalysts. Particular emphasis is placed on catalyst synthesis strategies, structural characteristics, mechanistic insights, stability, and cross-application potential. The review further evaluates the sustainability and techno-economic aspects of lignin-based catalytic systems and identifies current challenges and future opportunities. Integrating lignin-based materials in catalytic processes presents great potential for the purification of fuel while demonstrating a pivotal shift toward circular bioeconomy.