本文選題：汽爆玉米秸稈 + 半同步糖化發(fā)酵��； 參考：《江南大學(xué)》2017年碩士論文

【摘要】：目前,纖維素乙醇生產(chǎn)過程中過高的生產(chǎn)成本嚴(yán)重阻礙了其商業(yè)化進(jìn)程。研究者們認(rèn)為造成纖維乙醇生產(chǎn)成本較高的主要原因之一是纖維素乙醇生產(chǎn)工藝未達(dá)到淀粉基乙醇發(fā)酵的“三高”(高濃度、高轉(zhuǎn)化率和高發(fā)酵強(qiáng)度)指標(biāo),并且認(rèn)為實現(xiàn)纖維素乙醇高濃發(fā)酵是解決此問題的關(guān)鍵。為此,本文以汽爆處理后玉米秸稈為原料,考察不同處理方法對其組分和可酶解性的影響,并進(jìn)一步的研究處理后汽爆玉米秸稈的半同步糖化高濃發(fā)酵產(chǎn)乙醇工藝,具體研究內(nèi)容和結(jié)果如下:(1)汽爆玉米秸稈甘油有機(jī)溶劑處理和堿性過氧化氫處理條件優(yōu)化以及處理方法的選擇。其中甘油有機(jī)溶劑處理最優(yōu)工藝條件為:溫度110℃、處理時間1 h、甘油濃度70%和NaOH添加量為0.1 g·(g原料)~(-1),在該處理條件下汽爆玉米秸稈中纖維素含量提高到57.4%,木質(zhì)素降低到15.5%。堿性過氧化氫處理最優(yōu)工藝條件為:過氧化氫濃度2%、溫度23℃、固液質(zhì)量比10/110和處理時間2 h,在該處理條件下汽爆玉米秸稈中纖維素含量提高到61%,木質(zhì)素含量降為7.0%。另外,對甘油有機(jī)溶劑處理后汽爆玉米秸稈(GOT-SECS)、堿性過氧化氫處理后汽爆玉米秸稈(AHT-SECS)和未處理的汽爆玉米秸稈(SECS)進(jìn)行可酶解性考察,發(fā)現(xiàn)在15 FPU·(g底物)~(-1)加酶量和2%底物濃度下,酶解48 h后GOT-SECS、AHT-SECS和SECS的產(chǎn)糖率分別為515 mg·g~(-1)、620 mg·g~(-1)和265 mg·g~(-1)。因此,選擇堿性過氧化氫處理作為汽爆玉米秸稈的再處理方法。(2)AHT-SECS半同步糖化高濃發(fā)酵產(chǎn)乙醇過程優(yōu)化:通過對AHT-SECS高底物濃度酶解過程特性考察,確定其預(yù)酶解工藝為:以15.6%(w·v~(-1))為起始底物濃度,在酶解12 h時補(bǔ)加相當(dāng)于20%(w·v~(-1))初始底物濃度的干物料以及相應(yīng)量酶液后繼續(xù)酶解24 h。在該預(yù)酶解工藝基礎(chǔ)上,探究了培養(yǎng)基成分和培養(yǎng)條件對乙醇發(fā)酵的影響,確定了發(fā)酵條件:酵母提取物16 g·L~(-1)、接種齡20 h、接種量0.6 g·L~(-1)、發(fā)酵溫度39℃和PEG40000.01 g·(g干基質(zhì))~(-1)。在此發(fā)酵工藝條件下,發(fā)酵24 h后,乙醇產(chǎn)量達(dá)73.7 g·L~(-1),發(fā)酵強(qiáng)度為3.07 g·(L·h)~(-1),乙醇得率為61%。(3)通過強(qiáng)化AHT-SECS預(yù)酶解過程來提高其半同步糖化高濃發(fā)酵產(chǎn)乙醇效率。強(qiáng)化后的AHT-SECS半同步糖化高濃發(fā)酵產(chǎn)乙醇工藝為:以14.5%(w·v~(-1))為起始底物濃度,分別在酶解4 h、8 h和16 h向酶解體系中補(bǔ)加相當(dāng)于5%、7%和9%初始底物濃度的干物料,在酶解開始時加入所有所需酶液和4個直徑為9 mm的玻璃珠,整個預(yù)酶解過程為36 h,其他發(fā)酵培養(yǎng)基和發(fā)酵條件同(2),在該工藝條件下發(fā)酵24 h后乙醇產(chǎn)量達(dá)到81.2 g·L~(-1),發(fā)酵強(qiáng)度為3.38 g·(L·h)~(-1),乙醇得率為67.2%。
[Abstract]:At present, the high production cost of cellulosic ethanol seriously hinders its commercialization process. The researchers believe that one of the main reasons for the high cost of cellulosic ethanol production is that the cellulosic ethanol production process does not meet the "three high" (high concentration, high conversion and high fermentation intensity) targets for starch-based ethanol fermentation. The key to solve this problem is to realize high concentration fermentation of cellulosic ethanol. Therefore, the effects of different treatment methods on the composition and enzymatic hydrolysis of corn straw after steam explosion treatment were investigated, and the semi-synchronous saccharification and high concentration fermentation process of ethanol production from steam explosion corn stalk was further studied. The specific research contents and results are as follows: 1) Optimization of organic solvent treatment and alkaline hydrogen peroxide treatment of glycerin from steam explosion corn straw and selection of treatment methods. The optimum conditions of glycerol organic solvent treatment were as follows: temperature 110 鈩，

本文編號：1864919