Poplar Liquefaction in Water/Methanol Cosolvents

Abstract

Poplar liquefaction (PL) in methanol, water or water/methanol co-solvents (WMCSs) was investigated at 240-320 o C for 0-90 min. The results show that the yields of bio-oils (BOs) obtained from PL in WMCSs are higher than those in either methanol or water, indicating that methanol has synergic effect with water on PL. The maximum BO yield of 44.2% was obtained at 270 o C for 15 min in a WMCS containing 70 vol% of water. The BOs were analyzed with a gas chromatograph/mass spectrometer (GC/MS) and Fourier transform infrared (FTIR) spectrometer.Poplar and its residues were analyzed with the FTIR spectrometer and a scanning electron microscope (SEM). The fiber structure of poplar was significantly destroyed during PL in WMCS based on the SEM observation. According to GC/MS analysis, the BOs mainly consist of hydrocarbons, phenols, furans, other ethers, aldehydes, ketones, carboxylic acids, esters, and nitrogen-containing organic compounds. Among of them, phenols, ketones, and esters are the main group components. To investigate the liquefaction mechanism, the three major components in biomass, i.e., cellulose, hemicellulose, and lignin, were subjected to degradation in the same solvents. The results suggest that WMCS exhibits better synergic effects for cellulose and hemicellulose than for lignin. Further investigations are needed for detailed mechanism on synergic effects.

Sweet sorghum stalk liquefaction in supercritical methanol: Effects of operating conditions on product yields and molecular composition of soluble fraction

“…In other words, the optimal temperature should be 300°C for obtaining maximum BO yield of 40.5% from SSS liquefaction. Comparing to our previous studies [26,28], the BO yield obtained from either cornstalk or poplar liquefaction is ca. 10% less than that from SSS liquefaction.…”

“…MBs (Table 5) should be originated from the depolymerization of lignin in SSS [26]. The total yield of PCs first increased but then decreased under the reaction conditions.…”

“…Functional groups of SSS, the residues, and the BOs were measured with a Nicolet Magna IR-560 Fourier transform infrared (FTIR) spectrometer equipped with an EQUINOX55 spectrophotometer using KBr daf: dry and ash-free base; db: dry base: M ad : moisture (air dried base); A d : ash (dry base); V daf : volatile matter (dry and ash-free base); a by difference. (GC/MS) equipped with a HP-5MS capillary column and a quadrupole analyzer with a m/z range from 33 to 500 and operated in electron impact mode [26]. The column temperature was programmed from 60 to 240°C at a rate of 3°C min −1 , then raised to 300°C at a rate of 10°C min −1 and held at that temperature for 5 min.…”

“…Noteworthily, the total yield of ketones almost trended contrary to that of esters under the reaction conditions. Ketones and esters mainly come from cellulose and hemicellulose decomposition [26,38]. As a result, the competition may exist in the formation process of ketones and esters.…”

A Review of Hydrothermal Liquefaction of Biomass for Biofuels Production with a Special Focus on the Effect of Process Parameters, Co-Solvents, and Extraction Solvents

“…It was found that a 50/50 (v/v) ratio of a methanol-water mixture provided heavy oil with the highest phenol content. In a similar study, Yan et al [134] reported that methanol is effective for the degradation of cellulose and hemicellulose, whereas better lignin degradation is found when only water is used. Water contributed to the hydrolysis of cellulose and hemicellulose components, and led to ketone formation through cyclization reactions and methanol-facilitated esterification reactions [131,134].…”