|
The wide range of sources of plant cellulose materials and renewable bioethanol clean sound makes bioethanol countries development and research hotspot. Technical bottleneck of plant cellulose feedstock preparation of fuel ethanol plant cellulose pretreatment, and so far researchers have taken a variety of measures have not achieved the desired effect. This article intends to explore more effective pretreatment method. Respectively using supercritical water, N, N-dimethyl acetamide (LiCl / DMAc), and 1 - butyl-3 - methylimidazolium chloride ([BMIM] Cl) and 1 - allyl-3 - methyl-imidazole chloro ([AMIM] Cl), hydrolyzed or dissolving treatment of straw, microcrystalline cellulose, cotton, regenerated cellulose using cellulase enzymatic pretreatment, as measured by reducing sugar yield pretreatment effect; comprehensive comparison, determine the most reasonable and effective pretreatment method. Hydrolysis of sugar-producing reaction in a batch reactor supercritical rice straw, investigated the influence of various factors on the rate of production of reducing sugar, the results show that the highest conversion rate of the reducing sugar 18.10%, the main byproduct of 5 - (hydroxymethyl) furfural and glycerin aldehyde; also investigated the microcrystalline cellulose, cotton hydrolysis, reducing sugar, the highest conversion rates were 25.10%, 36.02%. Synthesis of two ionic liquids [BMIM] Cl and [AMIM] Cl, infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy (1H NMR) analysis showed that the synthesized product is indeed the target product [BMIM] Cl 90.93% purity, [AMIM] Cl 85.82% purity. LiCl / N, N - dimethylacetamide, respectively, [BMIM] Cl and [AMIM] CL as solvent, using ordinary heating method and microwave heating method, dissolved rice straws, microcrystalline cellulose, cotton, and the enzymatic hydrolysis of a reducing sugar test. The results show that the [BMIM] Cl, [AMIM] Cl, LiCl / DMAc are plant cellulose pretreatment agent, have made a very good effect enzymatic hydrolysis, reducing sugar yield than untreated substantial increase , and were much higher than the reducing sugar yield of supercritical water treatment; LiCl / DMAc solvent rice straw reducing sugar yield of 98.06%, 98.67% (previous figures for ordinary heating conditions, the latter figure [BMIM] Cl as solvent for microwave heating conditions, the same below); rice straw reducing sugar yield of 86.44%, 86.95%; as solvent [AMIM] Cl, the best reducing sugar, rice straw The yield was 94.55%, 96.21%; unprocessed rice straw before reducing sugar yield (30.9%) were significantly higher than. The three solvents role in the strength of the order of [BMIM] Cl lt; [AMIM] Cl lt; LiCl / N, N - dimethylacetamide; microwave heating promoted enzymatic hydrolysis. FT-IR, XRD, SEM and other characterization methods of LiCl / N, N - dimethylacetamide [BMIM] Cl, [AMIM] Cl plant cellulose dissolution process and the dissolution mechanism. FT-IR test results show that the LiCl / N, N - dimethylacetamide [BMIM] Cl, [AMIM] Cl the role of the various types of plant cellulose before and after the treatment, the structure of the group is almost no change, indicating that the solvent and plant cellulose derivatization reaction these three solvents are good solvent. The XRD tests show that the polymorph does not occur before and after the dissolution of rice straw cellulose I type crystal structure, still, while the microcrystalline cellulose, dissolving crystalline structure almost disappeared from prior to dissolution of the cotton cellulose I type crystal structure into II structure. Dissolved, the degree of crystallinity of the various types of cellulose amorphous region increases, or almost amorphous state. SEM observation showed that the the three solvents treated cellulose surface morphology has undergone great changes. In addition, the article also discussed LiCl / DMAc solvent system, the ionic liquid [BMIM] Cl and [AMIM] Cl dissolved rice straw mechanism. In this thesis, processing rice straw after the ionic liquid recycling test. The results show that the [BMIM] Cl recovery rate of 82.5%, a purity of 97.46%, again dissolved rice straw obtained reducing sugar yield was 84.52%; AMIM] Cl recoveries were 85.82%, 93.56% purity, dissolved again rice straw obtained reducing sugar yield of 92.48%; ionic liquid can be successfully recycled and reused. Comprehensive comparison of several methods that [AMIM] Cl can be used as the first choice of plant cellulose pretreatment agent.
|