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Effect of ZSM-5 pore modification and gallium ions proximity inside the zeolite channels on ethanol conversion to liquid hydrocarbon yields.

Plasmonic nanostructures have been proposed as useful materials for photon harvesting applications. However, the mechanisms by which energy transfer occurs across interfaces formed between plasmoni...

Lignin valorization is significantly hindered by the intrinsic heterogeneity of its complex structures and variability of biomass feedstocks. Fractionation of lignin can overcome these challenges by producing functionally distinct lignin cuts that can be further tailored to end products. Herein, lignin was extracted and depolymerized from poplar by the co-solvent enhanced lignocellulosic fractionation method with renewable THF to obtain CELF lignin. Several solvents were screened to separate soluble and insoluble fractions from the parent CELF lignin. The ethanol soluble portion was then fractionated into different molecular weight cuts via sequential precipitation of the lignin by reducing the concentration of THF. The physicochemical structures of different CELF lignin cuts were elucidated by GPC and NMR techniques. These results suggest that CELF lignin cuts with lower molecular weight contain progressively higher phenolic and carboxylic acid OH groups, which can be more suitable as green antioxidants than the parent lignin.

The conversion of biomass derived furfural to 2-pentanol, a useful organic solvent and precursor for various types of fuels, was demonstrated with ∼71.1% yield in a single step over a Co–Cu/Al2O3 catalyst at 240 °C and 45 bar H2 pressure. The catalyst demonstrated sustained activity and selectivity for four subsequent recycles without regeneration. Co was proposed as the primary active site that enabled hydrodeoxygenation of furfural to produce methyl furan followed by ring opening, while Cu mitigated product degradation that occurred on pure Cu catalysts.

A robust method is needed to achieve high yield all-catalytic conversion of recalcitrant lignocellulosic biomass to transportation fuels while maximizing carbon utilization from raw substrates. To accomplish this, we developed an integrated strategy that combines homogeneous and heterogeneous reactions with a treatment-extraction step to coproduce 2-methylfuran (MF) and 2,5-dimethylfuran (DMF) directly from hardwood poplar while maintaining high catalyst activity. In the first step, poplar wood chips were treated with dilute FeCl3 in THF–water at subpyrolytic temperature to yield 93.5% furfural (FF) from xylan and 66.0% 5-hydroxymethylfurfural (HMF) from glucan. Concurrently, a highly pure lignin powder was obtained from the liquor by precipitation upon room temperature vacuum recovery of THF from the water. Afterward, FF and HMF were extracted from water into an organic phase consisting of toluene and 1,4-dioxane treated with Ca(OH)2. A second hydrodeoxygenation reaction using Cu–Ni/TiO2 catalyst yielded...

Converting lignocellulosic biomass to biofuels and bioproducts is significantly hindered by the innate recalcitrance of biomass to chemical and biological breakdown, and it usually requires a pretreatment stage in order to improve conversion yields. A promising novel pretreatment named Cosolvent Enhanced Lignocellulosic Fractionation (CELF) involving dilute acid treatment of biomass in a THF–water mixture was recently developed to overcome biomass recalcitrance. Detailed elucidation of physicochemical structures of the fractionated lignin that is precipitated from CELF pretreatment of hardwood poplar, also called CELF lignin, reveals transformations in its molecular weights, monolignol composition, and hydroxyl group content. Isolated CELF lignin revealed dramatic reductions in its molecular weight by up to ∼90% compared with untreated native lignin. Furthermore, CELF lignin’s β-O-4 interunit linkages were extensively cleaved after CELF pretreatment as indicated by a semiquantitative HSQC NMR analysis. Th...

5-(Hydroxymethyl)furfural (HMF) and furfural (FF) have been identified as valuable biomass-derived fuel precursors suitable for catalytic hydrodeoxygenation (HDO) to produce high octane fuel additives such dimethyl furan (DMF) and methyl furan (MF), respectively. In order to realize economically viable production of DMF and MF from biomass, catalytic processes with high yields, low catalyst costs, and process simplicity are needed. Here, we demonstrate simultaneous coprocessing of HMF and FF over Cu–Ni/TiO2 catalysts, achieving 87.5% yield of DMF from HMF and 88.5% yield of MF from FF in a one pot reaction. The Cu–Ni/TiO2 catalyst exhibited improved stability and regeneration compared to Cu/TiO2 and Cu/Al2O3 catalysts for FF HDO, with a ∼7% loss in FF conversion over four sequential recycles, compared to a ∼50% loss in FF conversion for Cu/Al2O3 and a ∼30% loss in conversion for Cu/TiO2. Characterization of the Cu–Ni/TiO2 catalyst by X-ray photoelectron spectroscopy, scanning transmission electron microsc...

Supported bimetallic catalysts have been demonstrated to enhance catalytic activity, product selectivity, and catalyst stability over supported monometallic catalysts for a range of catalytic reactions. However, the surface structure and composition of bimetallic particles can differ significantly from the bulk due to variations in surface energies and interactions with adsorbates, making the design of bimetallic catalysts with targeted properties and reactivities challenging. We report here the influence of catalyst support (Al2O3 and TiO2) on the surface composition and structure of bimetallic Cu–Ni nanoparticles with varying Ni weight loading (0, 0.5, 1.5, 3, 5, and 10 wt %) at a constant Cu loading of 5 wt % and a correlation to catalytic reactivity and stability in furfural (FF) hydrodeoxygenation (HDO). Analysis via depth-profiling X-ray photoelectron spectroscopy suggested that over a range of Ni compositions in Cu–Ni/Al2O3 catalysts, Cu and Ni were distributed evenly within bimetallic particles, a...