生物大分子的解聚研究

邱學(xué)青

摘 要：為了充分研究生物質(zhì)大分子的解聚機(jī)理，課題組對纖維素水解的關(guān)鍵影響因素、纖維素、半纖維素水解機(jī)理、木質(zhì)素解聚方式和表征、木質(zhì)素模型化合物的制備等關(guān)鍵科學(xué)問題進(jìn)行了探討。借助SEM、BET、XRD研究手段，研究了半纖維素的水解、纖維素的結(jié)晶度、聚合度對對纖維素水解的影響規(guī)律；借助TEM、EDXA-SEM和Raman等分析手段，從超微尺度入手，追蹤解聚過程中木質(zhì)素、半纖維素和纖維素在細(xì)胞壁中的分布變化。結(jié)果表明，半纖維素被水解移除后，生物質(zhì)表面孔洞增多，孔隙率、總孔容增大，從而促進(jìn)了纖維素的水解；相比于聚合度而言，晶型結(jié)構(gòu)對水解的影響更大。在酸性環(huán)境下，木質(zhì)素在細(xì)胞壁各層間發(fā)生遷移，而在堿性環(huán)境中木質(zhì)素會直接脫除。同時，該課題開展了在微波協(xié)同下的木質(zhì)素催化氧化解聚及液化解聚，并通過比較了不同的氧化劑的種類對解聚產(chǎn)物單苯環(huán)物質(zhì)收率的影響，并通過液質(zhì)聯(lián)用，高壓液相色譜等手段對解聚產(chǎn)物進(jìn)行定性和定量分析。結(jié)果表明，微波協(xié)同下在相對較低的溫度和壓力下獲得單苯環(huán)化合物的收率可達(dá)到15.2%。為了對木質(zhì)素的解聚機(jī)理進(jìn)行進(jìn)一步的研究，該課題合成了包含α-o-4，β-o-4和β-5鍵的木質(zhì)素模型物三聚體和四聚體，并通過氣質(zhì)聯(lián)用色譜和核磁共振色譜等手段進(jìn)行分析和表征。木質(zhì)素模型物的合成為后續(xù)的木質(zhì)素解聚機(jī)理奠定基礎(chǔ)，并為木質(zhì)素解聚為單酚類化合物的高收率目標(biāo)提供參考。

關(guān)鍵詞：解聚機(jī)理 纖維素 木質(zhì)素 模型物

Abstract：For the purpose of investigation of the depolymerization mechanism of biomass macromolecule，some key scientific issues were explored，including important factors responsible for the hydrolysis of cellulose，depolymerization mechanism of hemicelluloses and cellulose，characterization of degraded products of lignin，and preparation of model compounds of lignin.The distribution of lignin， hemicellulose and cellulose in the cell walls was traced from the perspective of superfine scale in the process of depolymerization by using TEM， EDXA-SEM and Raman spectroscopy. In addition， the effect of hemicelluloses hydrolysis， degree of crystallization and polymerization on the hydrolysis of cellulose was investigated by using SEM， BET， and XRD. The result revealed that lignin was migrated in the cell walls between the layers in the acidic condition and lignin was removed directly in alkaline environment. For further inspection， the dynamics of alkali treatment to dissolve the lignin were investigated. In the meanwhile， oxidation degradation and liquefaction depolymerization of lignin were carried out assisted with microwave irradiation. And then the different kinds of oxidants on the influence of the yield of the product were studied. Qualitative and quantitative analysis of the product were characterized by LC-MS and HPLC.For further study of the rule of lignin deploymerization， several lignin model compounds composed of α-o-4，β-o-4 and β-5 linkages were synthesized. The target products were characterized by GC-MS and NMR spectroscopy. The lignin model compounds laid the foundation for the subsequent study of the mechanism of lignin deploymerization and provided the reference to achieve high yield of phenolic compounds through the degradation of lignin model compounds.

Key Words：Deploymerization mechanism；Cellulose；Lignin；Model compounds

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