Jie Chang

Selective production of 4-ethylphenolics from lignin via mild hydrogenolysis.

Selective production of 4-ethylphenolics from lignin via mild hydrogenolysis was reported in this short communication. The hydrogenolysis of lignin was carried out in an autoclave with 65 vol.% ethanol/water as solvent, with 5% Ru/C, Pd/C and Pt/C as catalysts. The influences of catalysts, lignin species, and reaction conditions including reaction temperature, reaction time, and initial H(2) pressure on yield of target compounds were investigated. 3.1% 4-Ethylphenol and 1.3% 4-ethylguaiacol based on lignin could be obtained simultaneously from hydrogenolysis of corn stalk lignin, which is approximate to the yield obtained from petrochemical route. The results of this work showed that this novel method is a quite promising technique for the substitution of petrochemical route.

Solid fuel production by hydrothermal carbonization of black liquor.

Formaldehyde was used as a polymerization agent to perform hydrothermal carbonization of black liquor for solid fuel production from 220 to 285°C. Compared to hydrochar prepared without formaldehyde, hydrochar produced in the presence of a 2.8wt.% formaldehyde solution (hydrochar-F) had 1.27-2.13 times higher yield, 1.02-1.36 times higher heating value (HHV), 1.20-2.31 times higher C recovery efficiency, 1.20-2.44 times higher total energy recovery efficiency, 0.51-0.64 times lower sulfur content, and 0.48-0.89 times lower ash content. The HHV of hydrochar-Fs ranged from 2.2×10(4) to 3.0×10(4)kJ/kg, while the HHV of hydrochar-F produced at 285°C was 1.90 times greater than that of the raw material (black liquor solid). These considerable improvements indicated that formaldehyde was an effective additive in hydrothermal carbonization of black liquor.

Preparation of biomass hydrochar derived sulfonated catalysts and their catalytic effects for 5-hydroxymethylfurfural production

Amorphous carbon-based sulfonated catalysts were generated from four kinds of biomass (lignin, cellulose, wood meal and D-xylose) by hydrothermal carbonization at various temperatures (225, 245 and 265 °C) followed by sulfonation, with a yield of 36–56%. All of these catalysts showed aromatic structure, hydroxyl and carboxyl groups, with a density of SO3H groups between 0.56 and 0.87 mmol g−1. 5-Hydroxymethylfurfural (HMF) was produced from inulin in ionic liquids (ILs) in one step with the addition of carbon-based sulfonated catalysts, with a factual yield of 47–65% at 100 °C, 60 min. Moderate extension of reaction time (from 30 to 90 min) and increase of temperature (from 80 to 120 °C) promoted HMF production. Ethyl acetate was used as extractant, and about 39–55% of HMF can be recovered from ILs. One problem with these carbon-based sulfonated catalysts was that they would be partly deactivated in ILs for separate reuse, however, they can be easily regenerated by dilute sulfuric acid treatment. The carbon-based sulfonated catalysts exhibited good catalytic activity compared with traditional solid acid catalysts, and the carbon-based sulfonated catalyst/ILs reaction system showed high reusability. In consideration of the renewable as well as the high catalytic activity abilities, these biomass derived carbon-based sulfonated catalysts would be promising for industrial application.

Recovery of ionic liquid via a hybrid methodology of electrodialysis with ultrafiltration after biomass pretreatment

Hybrid membrane-based methodology of electrodialysis (ED) with ultrafiltration (UF) was employed to recover the IL BmimBr (1-Butyl-3-methylimidazolium bromide) after biomass fractionation. Ultrafiltration was used to remove the residual lignin in IL solutions. Influence of molecular weight interception of UF treatment, initial IL concentration in dilute section, applied voltage and flow rate in each section of ED module were studied in detail. In this study, the highest overall IL recovery ratio reached 75.2% and the current efficiency of ED process approached 79.1%. Besides, the highest IL recovery performance of specific energy consumption was about 514.1g/kw·h. Insight gained from this study suggests a potential methodology for IL recovery after the pretreatment process for biomass.

One Step Preparation of Sulfonated Solid Catalyst and Its Effect in Esterification Reaction

A carbon-based sulfonated catalyst was prepared by direct sulfonation and carbonization (in moderate conditions: 200 °C, 12 h) of red liquor solids, a by-product of paper-making process. The prepared sulfonated catalyst (SC) had aromatic structure, composed of carbon enriched inner core, and oxygen-containing (SO3H, COOH, OH) groups enriched surface. The SO3H, COOH, OH groups amounted to 0.74 mmol·g−1, 0.78 mmol·g−1, 2.18 mmol·g−1, respectively. The fresh SC showed much higher catalytic activity than that of the traditional solid acid catalysts (strong-acid 732 cation exchange resin, hydrogen type zeolite socony mobile-five (HZSM-5), sulfated zirconia) in esterification of oleic acid. SC was deactivated during the reactions, through the mechanisms of leaching of sulfonated species and formation of sulfonate esters. Two regeneration methods were developed, and the catalytic activity can be mostly regenerated by regeneration Method 1 and be fully regenerated by regeneration Method 2, respectively.

A direct synthesis of adsorbable hydrochar by hydrothermal conversion of lignin

ABSTRACT Hydrothermal conversion of lignosulfonate with or without formaldehyde as polymerization agent was conducted at 320°C. Compared with the hydrochar produced without formaldehyde addition (WF-hydrochar), the yield and surface area of the hydrochar produced with formaldehyde addition (F-hydrochar) increased 33.8 and 46.4%, respectively. The F-hydrochar showed much higher adsorption ability of Cu2+ than that of WF-hydrochar, while its adsorption ability of methyl orange was a little lower than that of WF-hydrochar. These discoveries explored a high yield of hydrochar production and a potential new application of hydrochar.

Research on the quick and efficient recovery of 1-allyl-3-methylimidazolium chloride after biomass pretreatment with ionic liquid-aqueous alcohol system

Membrane-based methodology electrodialysis (ED) was employed for the quick and efficient recovery of ionic liquid AmimCl from the aqueous solutions after biomass pretreatment with AmimCl-aqueous methanol/ethanol systems. IL recovery performance was relatively stable as the variation of IL-alcohol systems employed in the pretreatment process. IL recovery ratio (R) of 66%-71%, IL recovery performance of specific energy consumption (Sp) of 429-467g/kwh and IL transport rate (Tr) of 5.3-8.2g/(m2min) were obtained by single ED treatment. Enhanced IL recovery performance was resulted with the semi-continuous ED-assisted process with R reached 93% and Sp reached 482g/kwh. Based on the characteristics of IL solutions, influence of different AmimCl-based solvents pretreatment on IL recovery was discussed and feasibility of electrodialysis treatment for such IL recovery task was also analyzed. Potential gained from this study suggests a feasible methodology for the quick and efficient recovery of ionic liquid after biomass pretreatment.

Phenolic Antioxidant Production by Hydrothermal Liquefaction of Lignin

Hydrothermal treatment of lignin was conducted using a batch reactor to obtain phenolic compounds between 260–350°C at various reaction times. It was found that at 320°C, 30 min, the max unit total phenol content of liquid product was obtained. With the 1,1-diphenyl-2-picrylhydrazyl radical method, the antioxidant activity and total phenol content correlated well. The liquid product improved the thermal oxidation stability of tung oil obviously at 130°C. The liquid product is a promising antioxidant at relatively low temperature.

Cellulose enzymatic saccharification and preparation of 5-hydroxymethylfurfural based on bamboo hydrolysis residue separation in ionic liquids

Ionic liquid/ethanol was used in bamboo hydrolysis residue (BHR) to separate lignin and cellulose. The optimal dissolution conditions were as follows: 160xa0°C, 150 min, 1u2006:u20061 of volume ratio of [AMIM]Cl to ethanol, 1u2006:u200610 of mass ratio of solid to liquid, when the dissolution rate was 41.7%, the purity of crude lignin was 86.7%, while that of cellulose product was 92.0%. Additionally the recycling effect of [AMIM]Cl/ethanol was ideal. The crystal structure of cellulose had not been destroyed; its crystallinity increased. Cellulose enzymatic saccharification was investigated, and the optimum process conditions were as follows: 50 °C, 48 h, 2 g L−1 of cellulase concentration, pH = 4.5, when the saccharification yield reached 83.7%. The cellulose crystal structure was destroyed and its degree of crystallinity was decreased after saccharification. Then the monosaccharide was used to convert to 5-hydroxymethylfurfural (5-HMF) under Bronsted acids or Lewis acids catalysis in [AMIM]OAc. It was found that the catalytic effect of Lewis acids was much better than that of Bronsted acids investigated, especially CrCl3. Choosing CrCl3 as catalyst, the optimum process conditions were as follows: 1u2006:u200610 of mass ratio of solid to liquid, 10 mol% (based on monosaccharide) CrCl3, 160 °C, 3 h, when the 5-HMF yield reached 56.8%.

Synthesis and characterization of phenol–furfural resins using lignin modified by a low transition temperature mixture

A new modification method based on an oxalic acid/choline low transition temperature mixture was used to activate the chemical groups of lignin as a substitute for phenol in phenol–furfural resins. The optimum modification conditions were 100 °C and 6 h at a molar ratio of oxalic acid to choline chloride of 1u2006:u20062. The content of phenolic –OH in the modified lignin increased from 1.75 to 3.01 mmol g−1 and the content of –OCH3 decreased from 10.86 to 8.57 wt%, increasing the reactivity of lignin. The modified lignin was partially substituted for phenol at various substitution rates in the synthesis of phenol–furfural (PFU) resins. When the substitution rate of lignin to phenol was 50%, the lignin–PFU had a high bond strength (up to 1.84 MPa) and a low free phenol content and the lignin–PFU showed a higher curing rate and thermostability than PFU alone. The oxalic acid/choline chloride low transition temperature mixture was shown to be an efficient and green lignin modification method for the synthesis of PFU.