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Design and assessment of alkaline kraft lignin valorization routes for high-added value applications
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Kemian tekniikan korkeakoulu |
Master's thesis
Electronic archive copy is available via Aalto Thesis Database.
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CHEM3057
Language
en
Pages
70
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Abstract
Lignin, a biopolymer found in plant tissues, represents the most abundant source of renewable aromatics, accounting for approximately 20-30% of the dry weight of woody species. Despite its abundance, lignin is often underutilized, typically considered a low-value by-product in the pulp and paper industry, and burned for steam and electricity generation. This limited utilization presents an opportunity for the bioeconomy, as the valorization of lignin into high-added value products can address environmental concerns and also stimulate economic growth. Phenol-formaldehyde resins, traditionally derived from petroleum-based phenol and formaldehyde, can be effectively produced using lignin as a substitute for the phenol. Similarly, polyurethane foams, which also come from petroleum-based chemicals, can incorporate lignin-based polyols to achieve comparable mechanical properties and thermal insulation. In the first part of this thesis, an LCA was con-ducted to assess the environmental impact of extracting lignin using the novel Large Pore Membrane Filtration (LPMF) technology on a pilot scale. The second part assesses the economic feasibility of using this lignin in two different process-es, producing either lignin-based phenol-formaldehyde resins or rigid polyurethane foams. The LCA used mainly primary data and Ecoinvent v3.10 as a data-base, and the software Aspen Plus v.14 was used for process simulation and eco-nomic evaluation. The process simulations include detailed design and sensitivity analyses to assess the impact of raw material and product price fluctuations. The LCA results showed a cradle-to-gate climate change impact of 0.22 kg CO2/kg lignin, which is comparable to other lignin extraction processes. The TEA indicate that lignin-based phenol-formaldehyde resins and polyurethane foams are eco-nomically viable. For both industries operating a capacity of 15kton of lignin per year, payback periods of 4.06 and 2.08 years were found for phenol-formaldehyde resins and polyurethane, respectively. In addition, a replacement ratio of 30% (wt% of phenol or polyol) can potentially lead to a reduction in CO2 emissions of 17.2% in the case of phenolic resins and 11.5% for the polyurethane one. Future research should focus on increasing the replacement ratio and development of improved functionalities.