Junfeng Feng

One-step method to produce methyl-D-glucoside from lignocellulosic biomass

One-pot acid-catalyzed methanolysis was applied to the liquefaction of biomass to obtain a high molar yield of methyl-D-glucoside at moderate temperature in a short time. A high bamboo conversion ratio (85 wt%) of bamboo and high molar yield of methyl-D-glucoside (40.6 mol%) were achieved. The conditions for high yield were methanol/bamboo mass ratio of 7 (350 mL methanol and 40 g bamboo), 2.0 wt% of catalyst, reaction temperature of 200 °C and reaction time of 10 min. Both hemicelluloses and cellulose (holocellulose) in the lignocellulosic biomass can convert into methyl-D-glucoside, a key and stable product. Methanolysis of biomass proved more efficient than its hydrolysis with an acid catalyst under similar reaction conditions, in water glucose yields were reduced to only 2–8 mol%.

Effective saccharification of holocellulose over multifunctional sulfonated char with fused ring structures under microwave irradiation

An environmentally benign process for hydrolysis of holocellulose conversion into sugars has been presented in this work, using sulfonated char (SC) catalysts derived from microcrystalline cellulose, hemicellulose, lignin and lignin-rich residues. Significantly, the SC catalysts exhibited remarkable hydrolysis performance for holocellulose under microwave irradiation, especially with sulfonated char from lignin (SCL) and sulfonated char from residues (SCR). The maximum conversion of holocellulose could reach 82.9% using SCR catalyst, with 26.8 wt% content of monose and 72.2 wt% content of oligose. The as-synthesized SC catalysts were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy (RS), Fourier transform infrared spectroscopy (FT-IR), thermal gravity analysis (TG) and elemental analysis (EA), which demonstrated that the SC catalysts possess a graphene-like fused ring structures, bearing SO3H, COOH and phenolic OH groups. The excellent catalytic performance could be attributed to the synergetic combination of the fused ring structures and multifunctional groups in the SC catalysts. This process could offer a promising strategy for efficient conversion of biomass in the future.

Renewable platform chemicals from directional microwave-assisted liquefaction coupling stepwise extraction of waste biomass

Directional microwave-assisted liquefaction and stepwise extraction are introduced for producing platform chemicals: aromatics and monosaccharides. When sulfuric acid was used as a catalyst, a 45% monosaccharides yield and a 29% aromatics yield were obtained from bamboo with 0.3g catalyst per 18g methanol and 2g bamboo at 160°C with 10min. Approximately 78-86wt% of the six biomass materials were converted into liquid products. After the stepwise extraction and precipitation process, the yields of monosaccharide derivatives and three phenolic compound fractions were 39-45% and 28-32%, respectively. Monosaccharides from holocellulose collected with a high purity of methyl glycosides were higher than 90%. Aromatic derivatives with different weight-molecular distributions were separated into three fractions with more than 80% phenolics. As their similar chemical properties within each fraction, platform chemicals have great commercial potential for producing high-quality chemicals and biofuels using mild upgrading conditions.

Characterization of depolymerized lignin and renewable phenolic compounds from liquefied waste biomass

This investigation aimed to analyze the renewable phenolic compounds that separate from liquefied mason pine. One-step thermal conversion of biomass to phenolic products from waste mason pine using an acidic catalyst and methanol was accomplished under mild conditions. Three fractions (fractions 1#, 2#, and 3#) of phenolic compounds with high added-value were extracted with water–organic solvent from liquefied oil via a stepwise fractionation process. The structural features of three phenolic compounds and depolymerized lignin were analyzed and identified by a combination of heteronuclear single quantum correlation-nuclear magnetic resonance, gel permeation chromatography, Fourier transform infrared spectroscopy, and thermogravimetric analysis, showing interesting functionalities for biochemical and biofuel applications. In this investigation, guaiacyl (G) and p-hydroxybenzoate (PB) aromatics were the basic units of three phenolic compound fractions. Etherified syringyl aromatics were evident in fractions 1# and 3#. There were only single-aromatic-ring units (such as G and PB units) in phenolic compound fraction 2#. In the aromatic region, the absence of β-O-4′ ether linkage, resinol, and phenylcoumaran units in three phenolic compound fractions indicated that depolymerization of lignin occurred during the liquefied biomass process. The molecular weights of three phenolic compound fractions were significantly different (797, 249, and 497, respectively) along with fractions 1#, 2#, and 3#. The phenolic compounds could be separated into a high, lower, and lowest molecular weight fraction in this study. As evidenced by GC-MS spectra, the three phenolic compound fraction products and depolymerized lignin were mainly comprised of phenolic derivatives, such as 3-methyl-4-ethylphenol, 4-ethyl-2-methoxyphenol, and 3-methylcatechol. Percentages of the total phenols and derivatives in the three phenolic compound fractions and depolymerized lignin were 77.59%, 81.76%, 80.19%, and 78.86%, respectively. Therefore, the three phenolic compound fractions were clearly quantified and valuable, and can be used as chemical products.