Decarbonisation Technology November 2026 issue

Can lignin become a refinery feedstock? With targeted pretreatment and use of existing brownfield infrastructure, lignin could become a valuable renewable carbon feedstock for the refining sector

Simge Oğuz Ankara University, Department of Chemical Engineering Vahide Nuran Mutlu SOCAR Türkiye R&D and Innovation Co.

R efineries are built around carbon. The question is increasingly where that carbon comes from. As the refining and petrochemical industries look beyond fossil feedstocks, attention has increasingly turned to biomass-derived carbon that can be connected to existing industrial infrastructure. However, not all biomass streams are equally attractive to a refinery. Their composition, oxygen content, moisture, inorganic contaminants, and conversion requirements can determine whether they can be integrated into established processes or require an entirely new value chain. Lignin presents a different case. Unlike conventional aliphatic biomass, lignin provides an industrial-scale source of aromatic carbon with potential relevance to petrochemical infrastructure. Under appropriate cracking and upgrading conditions, its phenolic structure can be converted into aromatic and cycloalkane- rich products. This makes lignin a potential refinery feedstock, provided the challenges of conversion and integration can be addressed. When integrated into suitable catalytic conversion routes, lignin-derived streams can contribute to gasoline-range products, marine and middle-distillate fuels, and high-value aromatic building blocks for the petrochemical industry. By serving a broader product portfolio, lignin could therefore move beyond its traditional role as a source of process energy and become a potential feedstock for higher-value applications. The question, however, is how this carbon can be converted into a form that a refinery can process. Beyond the paper: The Kraft fibre economy To enable large-scale refinery integration,

securing a reliable lignin source is essential. Viewing this resource merely as a by-product of the printing paper industry does not capture the broader Kraft fibre economy. Kraft pulping supports a wide range of paper, packaging, paperboard, and fibre products, creating an established industrial basis for lignin generation. On a global scale, the pulp and paper industry generates approximately 50 million metric tons of Kraft lignin annually ( Bajwa, Pourhashem, Ullah, & Bajwa, 2019; Dessbesell, Paleologou, Leitch, Pulkki, & Xu, 2020 ). Currently, more than 98% of this lignin is burned on-site within “ When integrated into suitable catalytic conversion routes, lignin- derived streams can contribute to gasoline-range products, marine and middle-distillate fuels, and high-value aromatic building blocks for the petrochemical industry ” mill recovery boilers as black liquor to meet internal energy requirements for steam and power generation, leaving less than 2% isolated for non-energy applications ( Chio, Sain, & Qin, 2019 ). While internal combustion enables energy self-sufficiency, recovery boilers often represent the principal operational bottleneck for pulp production expansions ( Tomani, 2010 ). Consequently, extracting a portion of the lignin for downstream refining not only provides an abundant biogenic carbon stream, but also debottlenecks the recovery boiler, allowing pulp mill throughput to increase ( Tomani, 2010; Benali, Kouisni, & Paleologou, 2014 ).