Dong Li

Furfural is an essential platform chemical for the lignocellulosic bioeconomy, yet its sustainable synthesis in pure aqueous media remains severely bottlenecked by the hydrolytic instability and poor selectivity of conventional solid acids. Herein, we report on the rational design of highly robust, tunable phosphorus (P)-doped carbon solid acids that overcome these limitations, enabling the highly efficient, hydrothermal conversion of biomass-derived hemicellulose to furfural. By precisely modulating the P-doping threshold, an optimal synergistic equilibrium between highly specific Lewis acid (LA) and Brønsted acid (BA) sites has been achieved. The top-performing catalyst, CBSA-P0.3, delivered an exceptional furfural yield of 71.1% from xylose (180 ºC, 4 h) and 39.2% from raw corncobs (180 ºC, 2 h), operating exclusively in an environmentally benign aqueous medium. Comprehensive mechanistic elucidations revealed that uniquely active P-containing moieties, specifically C3–P=O and C–PO3/C2–PO2 groups, function as kinetically dominant LA engines driving the critical xylose isomerization step, while intrinsic oxygenates on the carbon scaffold (–COOH and –OH) act as robust BA reservoirs for subsequent rapid dehydration. Crucially, tailored P-functionalization maximizes active-site accessibility while suppressing the non-specific interfacial adsorption of furfural, thereby inhibiting humin polymerization pathways. Conversely, excessive doping severely impedes catalytic turnover by inducing structural pore collapse and the heavy accumulation of sterically hindering, catalytically inert adsorbed phosphates. This study provides profound mechanistic insights into the precision regulation of acid sites in P-doped carbons, establishing a disruptive, scalable, and entirely green catalytic blueprint for next-generation aqueous-phase biorefineries.

Global demand for protein now exceeds 200 million tonnes annually and is projected to rise to around 280 million tonnes by 2050. Meeting this demand requires diversifying protein sources beyond conventional animal- and plant-based products. Microbial proteins offer a promising alternative to traditional food and feed sources by reducing dependence on conventional agricultural systems and mitigating the environmental impacts of livestock farming. However, large-scale production of microbial proteins is currently hindered by the scarcity of cost-effective raw materials and the lack of efficient bioconversion technologies. This paper outlines strategies to accelerate the near-term scale-up of microbial proteins using low-value carbon sources. These include establishing feedstock databases, engineering robust strains for crude substrate utilization, and integrating advances in metabolic and process engineering. We further emphasize the importance of pilot- and demo-scale validation, regulatory streamlining, and cross-sector collaboration to enable sustainable and economically viable industrial deployment.

Conventional biorefining of lignocellulosic biomass, such as corn stover (CS), is hampered by poor carbon efficiency, as nearly half of the substrate carbon is lost as CO₂ during ethanol fermentation. This study presents a holistically integrated cascade process designed to capture and valorize all major carbon streams. The system synergistically couples three stages: (1) high-productivity ethanol fermentation (1.68 g/L/h) using the engineered yeast Saccharomyces cerevisiae CE10; (2) anaerobic digestion of the resulting stillage, which efficiently converted residual organics into methane (171 L/kg COD) with ca. 80% COD removal; and (3) cultivation of the cyanobacterium Desertifilum tharense BERC03 using the nutrient-rich digestate and captured fermentation CO₂. This integrated approach boosted the carbon utilization from a baseline of 48% to 62%. A comprehensive techno-economic analysis of an industrial-scale (2000 t/d) facility projected a Minimum Ethanol Selling Price (MESP) of $2.44 per gallon, a value approaching current market competitiveness. The analysis identified the feedstock (30%) and cellulase (17%) as the primary cost drivers. These findings demonstrate a validated biorefinery model that significantly enhances carbon recovery and outlines a viable pathway for the coproduction of multiple biofuels from lignocellulosic resources.

The development of a cost-effective process for biomass conversion into sugar platforms is a cornerstone of sustainable biorefining. Here, we report a Lewis acid-controlled catalytic strategy for nonenzymatic sugar production from hemicellulose in biomass using a highly active, magnetically separable core–shell catalyst. The catalyst comprises a Fe₃O₄ magnetic core, an acid-resistant silica interlayer, and a phosphorus (P)-doped porous carbon shell. Under mild hydrothermal conditions, the optimized catalyst (MC₆₀₀P_1.2) achieved a xylose yield of 86.9% from xylan (100 °C for 2 h) and 60.3–91.0% from diverse biomass feedstocks (corncob, corn stover, poplar, and bamboo, 160 °C for 2 h), outperforming previously reported systems. Such remarkable catalytic activity is attributed to the unique structural design of the catalyst. The silica interlayer acts as a protective shield of Fe₃O₄ core and bonds with the carbon layer to form a silica–carbon shell that provides an ideal scaffold. Meanwhile, P doping introduces defects and hydrogen bonds, enhancing the active site accessibility. The formation of thermally stable PO_x species (C–P–O, C₃–PO, and C–O–P) on the carbon support acts as Lewis acid sites. C–P–O efficiently activates H₂O to produce H⁺ for glycosidic bond cleavage and suppresses xylose degradation, ensuring a high yield. These features result in high catalytic stability and reusability, maintaining high xylose yields after three consecutive cycles. This work provides new research avenues to produce nonenzymatic sugar based on active, deactivation-resistant, and easily recoverable heterogeneous catalysts.

Transporting water contained in lignocellulosic biomass is both costly and impractical. Thus, the inevitable increase in the utilization of biomass derived products such as hygroscopic nanocellulose and dissolving pulp cellulose prior to downstream chemical/enzymatic processing will necessitate a greater understanding of the potential drying induced impacts on the reactivity/accessibility of cellulose. To assess the effects of hemicellulose and lignin on the drying behavior and enzymatic hydrolysis of cellulose, corn stover was subjected to steam pretreatment, bleaching, and LiBr·3H₂O treatment to produce model substrates rich in holocellulose, cellulose-lignin, pure cellulose and the original composition. The model substrates were freeze-dried, air-dried, and oven-dried, and were subjected to Simons’ staining (both wet and dried samples) and N₂ adsorption analysis (dried samples) to assess cellulose accessibility and surface area. Drying-induced hornification reduced cellulose accessibility, with freeze-drying preserving the structure more effectively than oven or air drying. The presence of hemicellulose and lignin influenced drying-induced hornification by significantly increasing cellulose accessibility. Hemicellulose removal was as effective as lignin removal in enhancing enzymatic hydrolysis at low enzyme loading, but its presence played a key role in mitigating drying effects. Additionally, cellulose properties, such as the degree of polymerization, affected drying responses, as seen in the reduction of hydrolysis yield in endoglucanase-treated dissolving pulp.