Catalytic conversion of enzymatic hydrolysis lignin into cycloalkanes over a gamma-alumina supported nickel molybdenum alloy catalyst

Effect of W Modification on MoS2 Surface Edge in the Ethanolysis of Lignin into Platform Chemicals

A series of metal-doped MoS2, including W-, V-, and Re-doped MoS2, are prepared via a two-step hydrothermal method, which presents higher activity on the depolymerization of enzymatic hydrolysis lignin (EHL) in ethanol as compared to undoped MoS2. At 320 °C for 6 h, the highest overall aromatic monomer yield of 231 mg/g EHL, including alkylphenols (A-Ps) as the main products with a yield of 126.5 mg/g EHL, is obtained over two-step hydrothermally prepared W-doped MoS2 with the W/Mo molar ratio of 0.1 (Ts-W0.1@MoS2). The W-doped MoS2 sample gives higher enhancement of EHL bio-oils' heating value to 37.1 MJ/kg as compared to Re and V modified MoS2. Large distribution of W atoms on the MoS2 surface in two-step hydrothermally synthesized samples leads to the higher activity of EHL depolymerization than one-step prepared samples. The reduction of W precursors on the MoS2 surface in the preparation process promotes the generation of more Mo5+ and Mo6+, which plays important roles in the improvement of EHL depolymerization activity. The effect of the W-doping modification and the stability of W-doped MoS2 are discussed. The anti-sulfur loss and antioxidant abilities are significantly enhanced after W-doping modification. In the recyclability test, the good incorporation of W atoms with MoS2 surface and the gradual oxidation of W-based sites improve the balance of catalytic cycles among different Mo-based sites, which results in the increase of catalyst stability.

One pot bioprocessing in lignocellulosic biorefinery: A review

Practically, high-yield conversion of biomass into value-added products at low cost is a primary goal for any lignocellulosic refinery. In the industrial context, the limitation in the practical adaptation of the conventional techniques practically involves multiple reactors for the conversion of biomass to bioproducts. Therefore, the present manuscript critically reviewed the advancements in one-pot reaction systems with a major focus on the scientific production of value-added products from lignocellulosic biomass. In view of that, the novelty of one-pot reactions is shown during the fractionation of biomass into their individual constituents. The importance of the direct conversion of cellulose and lignin into a range of valuable products including organic acids and platform chemicals are separately discussed. Finally, the article is concluded with the opportunities, existing troubles, and possible solutions to overcome the challenges in lignocellulosic biorefinery. This article will assist the readers to identify the economic-friendly-one-pot conversion of lignocellulosic biomass.

Highly selective hydropyrolysis of lignin waste to benzene, toluene and xylene in presence of zirconia supported iron catalyst

The use of lignin to produce Benzene, Toluene and Xylene (BTX) is a promising pathway to strength the economic case, over the production of advanced bio-fuels alone. In this work, Ce, Na, Pd and Fe supported on zirconium oxide were evaluated for the ex-situ hydropyrolysis (HyPy)/hydrodeoxygenation (HDO) of Etek lignin under mild conditions (600 °C, 1 atmosphere) towards the production of BTX. Fe/ZrO₂ was able to selectively produce BTX (67 area%) and cycloalkenes (13.5 area%) and strongly deoxygenate the HyPy oil to about 5 wt% oxygen content, resulting in an oil with a carbon distribution of 85.5 % in C₅-C₁₀ hydrocarbons. The high selectivity of Fe/ZrO₂ was related to the iron oxophilicity, the strong reduction potential of zero-valent iron, the good dispersion of Fe nanoparticles on the support and the presence of mesopores and acid sites, which enhanced the interactions between the reacting species and the catalyst surface.

Detoxification of lignocellulosic prehydrolyzate by lignin nanoparticles prepared from biorefinery biowaste to improve the ethanol production

This study proposed a recyclable p-toluenesulfonic acid (p-TsOH) fractionation process for co-producing lignin nanoparticles (LNPs) and fermentable sugars from lignocellulosic biorefinery biowaste (enzymatic hydrolysis residue (EHR)). The prepared LNPs were used to detoxify the inhibitors in the xylose-rich prehydrolyzate for improving ethanol production. Results showed that the EHR was fractionated into a cellulose-rich water-insoluble solid (WIS) fraction and a lignin-rich spent liquor (SL) fraction. Cellulase hydrolysis of WIS produced 97.7% of glucose yield, while the LNPs of an average particle size of 98.0 nm with 76.3 % yield (based on the untreated EHR) were obtained from the diluted SL. LNPs demonstrated higher detoxification ability than EHR at the same dosage. Moreover, the fermentability of the detoxified xylose-rich prehydrolyzate was significantly improved. The sugar utilization ratio was 94.8%, and the ethanol yield reached its peak value of 85.4% after 36 h of fermenting the detoxified xylose-rich prehydrolyzate.

Fast hydropyrolysis of biomass Conversion: A comparative review

Recent studies show that fast hydropyrolysis (i.e., pyrolysis under hydrogen atmosphere operating at a rapid heating rate) is a promising technology for the conversion of biomass into liquid fuels (e.g., bio-oil and C₄₊ hydrocarbons). This pyrolysis approach is reported to be more effective than conventional fast pyrolysis in producing aromatic hydrocarbons and also lowering the oxygen content of the bio-oil obtained compared to hydrodeoxygenation (a common bio-oil upgrading method). Based on current literature, various non-catalytic and catalytic fast hydropyrolysis processes are reviewed and discussed. Efforts to combine fast hydropyrolysis and hydrotreatment process are also highlighted. Points to be considered for future research into fast hydropyrolysis and pending challenges are also discussed.