this intermediate undergoes stabilisation, deoxygenation, and further upgrading. Subsequently, the upgraded bio-oil can be integrated into suitable refinery infrastructure and co-processed alongside conventional hydrocarbon feeds at 1-5 wt% blend ratios. This cross-industry value chain creates potential advantages for both sides. The Kraft mill valorises a lignin stream beyond its conventional energy-recovery role and debottlenecks its recovery boiler, while the refinery gains access to biogenic carbon without replacing its core processing infrastructure. Can lignin become a refinery feedstock? Thermodynamic, chemical, and operability limits directly influence whether lignin- derived streams are suitable for refinery operations. Although lignin is an important source of renewable aromatic carbon for the petrochemical industry, raw lignin is not a drop- in feedstock for standard distillation columns or catalytic reactors. Making lignin-derived products commercially viable requires practical process engineering rather than chemical feasibility alone. Successful integration depends on several operational steps: developing a suitable thermochemical conversion route, removing alkali and oxygen contaminants, stabilising and upgrading the feed through processes such as HDO, and demonstrating compatibility with existing catalytic or hydroprocessing units. In short, the same molecule that creates processing challenges in pulp and paper mills could also help bridge the gap between the pulp and refining industries, provided it undergoes the necessary upgrading. Lignin is not a simple plug-and-play solution. However, with targeted pretreatment and the use of existing brownfield infrastructure where technically appropriate, it has the potential to become a valuable renewable carbon feedstock for the refining sector.
per day generates approximately 1,000-1,500 metric tons of dissolved lignin daily in its black liquor ( Paulapuro & Gullichsen, 2000 ). Extracting 15-20% of this lignin yields approximately 150-300 metric tons/day of solid isolated lignin ( Tomani, 2010; Benali, Kouisni, & Paleologou, 2014 ). • Petroleum refinery scale: A medium-to- large petroleum refinery processing 100,000- 200,000 barrels of crude oil per day (bpd) processes roughly 14,000-28,000 metric tons of crude oil daily (assuming standard crude density conversion of ~7.33 barrels/metric ton) ( American Petroleum Institute, 2021 ). • Co-processing context: The entire daily lignin extraction from a major pulp mill (~200 t/d) accounts for less than 1-2% of the daily feedstock volume processed by a mid-sized oil refinery. More circular carbon relationship between pulp and refining The technical constraints, upgrading strategies, and processing routes discussed in this article converge on a broader strategic framework: “ By positioning lignin as a potential carbon bridge, the pulp and petrochemical sectors could develop a more connected carbon value chain in which a currently lower-value stream is converted into higher-value fuels and chemicals ” cross-sector industrial symbiosis. By positioning lignin as a potential carbon bridge, the pulp and petrochemical sectors could develop a more connected carbon value chain in which a currently lower-value stream is converted into higher-value fuels and chemicals. The described value chain follows a clear mass-flow concept. The process begins with biomass feedstock, which is fractionated in the Kraft pulping process into cellulose for paper and packaging and lignin-rich black liquor. Rather than recovering all of the lignin solely through combustion, part of the lignin is precipitated and thermochemically converted into a bio-oil intermediate. To overcome hydraulic and catalytic incompatibilities,
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Simge Oğuz simge200346@gmail.com Vahide Nuran Mutlu vahide.mutlu@socar.com.tr
www.decarbonisationtechnology.com
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