Cellulose polymerization degree and crystal plane changing are both considered to affect acid hydrolysis,however,it is uncertain to identify which one is more important.In this study,the filter paper was treated with dilute hydrochloric acid to investigate the cellulose polymerization degree changing,and cotton linter was treated with NaOH for the purpose of changing its crystal plane.Both the treated and untreated samples were hydrolyzed under the condition of 1.0 wt%dilute hydrochloric acid with solid-liquid ratio 1:40 at 140℃for 30 min to compare the hydrolysis effects.It was found that the glucose yield increased from 9.5%to 19.7%when treated with 15%NaOH at 50℃for 30 min,and new crystal planes(1-10)(1-20)appeared after alkali treatment.According to the experimental results,it is concluded that crystal plane plays a vital role in cellulose acid hydrolysis.
The microwave assisted liquefaction process of wheat straw alkali lignin was investigated to obtain monophenolic compounds as the precursor of bio-fuel. It is found that the total yield of monophenolic compounds is significantly improved under microwave irradiation, reaching 15.77% under a relatively mild liquefaction condition of 10 wt% H2SO4 as the catalyst, 10 wt% phenol as the hydrogen-donor reagent at 120 ℃ for 40 rain. Compared with conventional thermal liquefaction process, microwave irradiation promotes the cleavage of C-C bonds, which gives an extra 29% of Caryl-Cα bond cleavage, and increases the yield of monophenolic compounds from 0.92% to 13.61% under the same conditions. The excessive temperature and prolonged time under microwave irradiation will promote the recondensation of degraded lignin fragments, so the key to obtain high yield of monophenolic compounds is to avoid the recondensation reaction. The selected solid catalyst promotes the dissociation of methoxy groups, and the addition of phenol into liquefaction can only slightly improve the yield of monophencolic compounds.
