Effective pretreatment is essential for producing fermentable sugars from lignocellulosic biomass. In this study, mixed-acid and organic-amine pretreatments were conducted for corncob deconstruction, component fractionation, lignin removal, and enzymatic saccharification. The sulfuric acid/maleic acid system (1:1, w/w) efficiently hydrolyzed hemicellulose, achieving glucose and xylose yields of 78.5% and 99.56%, respectively. 2D HSQC NMR analysis showed a clear decrease in the Cβ signal of β-O-4 linkages in G-type lignin units, indicating acid-catalyzed ether-bond cleavage. However, delignification in the acid system was limited to a maximum of 26.2%. In contrast, aqueous triethylamine pretreatment selectively removed lignin by cleaving ester and ether linkages in lignin-carbohydrate complexes while retaining most cellulose and hemicellulose. 2D HSQC NMR analysis revealed substantially weakened β-O-4 signals after amine pretreatment, indicating selective depolymerization with intact S and G units. Pretreatment with 30% triethylamine achieved 74% lignin removal. Enzymatic hydrolysis of the amine-pretreated residue gave 99.4% glucose, 89.1% xylose, and 93.7% total sugar yields. DFT calculations demonstrated that the amine system exhibits significantly stronger interactions with the lignin model (−32.78 kcal/mol) than organic acids (−18.52 and −15.08 kcal/mol), explaining its superior lignin affinity. These results show that mixed-acid pretreatment is suitable for xylose-oriented fractionation, whereas amine pretreatment is more suitable for delignification and glucose-oriented saccharification.
The sustainable bioeconomy is moving beyond its original role as a renewable-resource substitute for fossil production. That transition is occurring under simultaneous pressures from accelerating climate risk, transgressed Earth-system limits, biodiversity decline, resource insecurity, public-health impacts, rapid digitalization and geopolitical uncertainties. This critical review redefines the sustainable bioeconomy as a dynamic socio-ecological-technological system whose performance must be assessed across six interdependent pillars: climate mitigation and adaptation; circular and regenerative resource management; nature-positive development; human and planetary health; digital intelligence and responsible innovation; and socioeconomic resilience supported by adaptive governance. Recent high-impact evidence is synthesized to show why renewable biological origin alone is insufficient: bio-based pathways can lower emissions, recover nutrients and create new products, yet can also shift burdens to land, water, biodiversity, health, energy demand or vulnerable communities. This paper critically reviews complementary approaches relevant to bioeconomy assessment, including life-cycle assessment (LCA) and techno-economic assessment (TEA), corporate sustainability and Environmental, Social and Governance (ESG) frameworks, Sustainable Development Goal (SDG) and Earth-system-based approaches, Planetary Health and One Health frameworks, and systems, multi-criteria, and digitally enabled assessment methods. This analysis provides operational questions and maps the complementary roles and blind spots of major assessment approaches. Building on this synthesis, an integrated assessment framework and research roadmap are proposed in which minimum environmental and social safeguards, life-cycle and economic performance, resilience testing, transparent governance and continuously updated evidence are combined. The resulting perspective shifts the objectives of the bioeconomy from maximizing biomass utilization to sustaining regenerative, low-carbon and equitable system performance aligned with population health under changing climatic and societal conditions.
Sustainable aviation fuel (SAF) production from distributed biogenic carbon resources remains limited by the high capital intensity and process complexity of conventional gas-to-liquids (GTL) technologies. Here, we report the development and pilot-scale validation of Cool GTL™, an electrified, integrated GTL platform designed for the decentralized conversion of biogenic gas and CO2-derived carbon into drop-in transportation fuels. The process combines an internally electrically heated reformer, Fischer–Tropsch (FT) synthesis, and direct product upgrading in a compact configuration that eliminates external fired reformers, intermediate syngas conditioning, and stand-alone hydrocracking. The electrically heated reformer simultaneously converts CH4, C2⁺ hydrocarbons, steam, and CO2 through bi-reforming to produce synthesis gas with an H2/CO ratio of 2.0–2.55, enabling direct FT conversion without downstream adjustment. Unlike conventional GTL systems, the integrated upgrading reactor enables hydrocracking and hydroisomerization directly in the presence of CO, eliminating the need for CO removal and reducing the requirement for high-purity hydrogen supply. The fully integrated pilot plant demonstrated stable operation for more than 2,400 h using multiple carbon feedstocks and produced over 190 L of liquid hydrocarbons, with approximately 50 wt% distributed in the SAF boiling range. The optimized SAF fraction satisfied applicable ASTM fuel specifications, including freeze-point requirements. Compared with scaled-down conventional GTL designs, the simplified configuration reduced estimated capital cost by approximately 78% for a 2,500 bbl/d system. These results demonstrate an electrified, low-complexity GTL pathway that enables economically attractive decentralized production of SAF from biogenic carbon and CO2.
Biowaste valorization is increasingly promoted as a strategy for climate-change mitigation, yet converting waste into useful products does not inherently guarantee decarbonization. This review critically examines how biowaste can function as a renewable carbon resource and identifies the conditions under which its valorization delivers genuine life-cycle greenhouse-gas benefits. Biowaste streams are first classified according to physicochemical characteristics that govern pathway selection, followed by evaluation of biological, biochemical, thermochemical, chemical, and integrated biorefinery routes. Particular attention is given to five mechanisms through which valorization can contribute to decarbonization: avoidance of conventional waste-management emissions, displacement of fossil energy, displacement of fossil-derived chemicals and materials, carbon retention and durable removal, and decarbonization of the conversion process itself. The carbon value of resulting products is further assessed according to their function and residence time, distinguishing rapidly cycled fuels from chemicals, long-lived materials, stable carbon products, and geological storage of biogenic CO2. Methodological challenges in quantifying climate benefits are critically evaluated, with emphasis on system boundaries, functional units, allocation, substitution, counterfactual waste-management scenarios, temporal carbon accounting, and geographic energy mixes. Environmental burden shifting, economic viability, technological maturity, and scale-up constraints are also considered. Based on this synthesis, harmonized metrics and a feedstock-specific decision framework are proposed for selecting valorization pathways according to carbon performance, product function, economics, technological readiness, and spatial context. The review concludes that future biorefineries should evolve from biomass-conversion facilities toward integrated carbon-management systems that optimize fossil displacement, carbon utilization and permanence, environmental performance, and economic viability simultaneously.
The catalytic hydrogenolysis of aromatic C–O bonds in lignin to produce phenolic jet fuel precursors offers a promising route for lignin valorization. However, conventional methods often suffer from reliance on noble metal catalysts, harsh reaction conditions, and external hydrogen gas. Herein, we report a strategy using isopropanol as the in-situ hydrogen donor with non-precious Ni/CeO2 catalyst to hydrogenolyze lignin and lignin dimers under N2 atmosphere. The Ni/CeO2 catalyst proved highly effective in cleaving aromatic C–O bonds, mainly producing aromatic hydrocarbons and cyclohexanol. At 240 oC for 2.5 h, complete conversion of benzyloxybenzene (BOB) and 2-phenoxyphenylethanol (POPE) was achieved, and diphenyl ether (DPE) achieved 96.9 mol% conversion. A series of control experiments confirmed that Ni0 species serve as the primary active sites of Ni/CeO2, and the strong interfacial interaction between Ni and CeO2 also plays an indispensable role. For the depolymerization of organosolv lignin, syringyl (S), guaiacyl (G), and p-hydroxyphenyl (H) phenolic monomers are the main products, with carbon numbers ranging from C7 to C11, serving as effective phenolic precursors for jet fuel. A maximum monophenol yield of 36 wt% was achieved under the conditions of 240 oC, 7.5 h, and a catalyst/lignin mass ratio of 75/100. Characterization of the lignin oil and the spent catalyst confirmed that this system effectively depolymerizes lignin, with the catalyst exhibiting excellent structural stability and regenerability. In summary, this work provided an efficient approach for producing valuable phenolic precursors for jet fuel from lignin.
