In order to explore the feasibility of one-pot preparation of methyl levulinate (MLA)from biomass catalyzed by dilute sulfuric acid in near-critical methanol,the kinetics of MLA production were investigated at initial glucose concentration of 10—30 mg·ml-1,temperature range from 160 ℃ to 190 ℃,and sulfuric acid concentration between 0.01—0.06 mol·L-1.The results show that reaction temperature has a significant effect on the selectivity of MLA and higher yield of MLA is obtained at higher temperature.With the first-order kinetic equations,the activation energies evaluated are 107.5 kJ·mol-1 and 68.4 kJ·mol-1,and the reaction orders to H+ concentration are 0.981 and 0.953 for main and side alcoholysis reactions of glucose,respectively.The paper demonstrates that the one-pot process is promising for MLA production catalyzed by dilute sulfuric acid in near-critical methanol.
The decomposition kinetics of glucose and 5-hydroxymethylfurfural catalyzed by copper chloride were measured in small volume high-pressure vessel batch reactors,at various temperatures from 423.15 K to 463.15 K and catalyst concentration from 0 to 0.08 mol·L-1.The results showed that their conversion went up with the increase of reaction temperature and catalyst concentration,resulting in higher yield of levulinic acid.By comparing the correlation coefficients,it was confirmed that both glucose and 5-hydroxymethylfurfural decomposition are first order reaction.By using first order kinetics equation,the activation energies of desired and undesired reaction were estimated,134.65 kJ·mol-1 and 144.1 kJ·mol-1 for glucose decomposition,131.97 kJ·mol-1 and 135.18 kJ·mol-1 for 5-hydroxymethylfurfural decomposition,respectively.This work would provide important basic data not only for the exploration of reaction mechanism of glucose decomposition,but also for the development of high activity and high selectivity catalyst.
The solubilities of nizatidine in methanol + water, ethanol + water and i-propanol + water mixtures were determined in the temperature range from 273.15 K to 303.15 K at atmospheric pressure by a static analytical method. The general single model was used to correlate the experimental data, which fits the data very well.
The application of high temperature liquid water（HTLW） to decomposition of lignin as efficient and green solution for phenolic compounds recovery was studied.Benzyl phenyl ether（BPE）,the lignin model compound,was treated at temperatures ranging from 220 to 250℃.BPE undergo hydrolysis in HTLW,and main products were phenol and benzyl alcohol with the minimum selectivities of 75.7%and 82.8%,respectively.Lower temperature led to higher selectivity in 220-250℃temperature range.The kinetics on BPE hydrolysis was studied and the activation energy was determined as 150.3±12.5 kJ/mol with the first-order kinetic equations.Based on products distribution,the reaction mechanism for decomposition of benzyl phenyl ether was proposed.The investigated process provides insights into the design of a commercial method for utilization of lignin.
