本文選題：生物質(zhì)　切入點(diǎn)：木質(zhì)纖維素　出處：《中國(guó)科學(xué)技術(shù)大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：由于化石燃料的枯竭和對(duì)燃料需求的增加,開(kāi)發(fā)可再生資源用于生產(chǎn)替代能源和化學(xué)品顯得日益重要。木質(zhì)纖維素類生物質(zhì)以其來(lái)源廣、儲(chǔ)量大、不與人類爭(zhēng)糧食等優(yōu)點(diǎn),受到人們的關(guān)注。木質(zhì)纖維素類生物質(zhì)通過(guò)化學(xué)或生物手段可以轉(zhuǎn)化為許多產(chǎn)品,例如生物燃料(生物柴油、生物乙醇和沼氣)和化學(xué)品(醋酸、丙酮和乳酸),而現(xiàn)在部分產(chǎn)品可以替代石油的應(yīng)用。目前,通過(guò)酸水解或直接由兩級(jí)間接轉(zhuǎn)化等預(yù)處理手段將木質(zhì)纖維素中的碳水化合物轉(zhuǎn)化為可溶性單糖,再進(jìn)一步轉(zhuǎn)化為乙醇等生物燃料和高附加值化學(xué)品成為主要的處理過(guò)程。固體酸催化劑具有活性高、選擇性好、腐蝕性小、催化劑壽命長(zhǎng)和易于回收再利用等優(yōu)點(diǎn),能夠?qū)⒛举|(zhì)纖維素生物質(zhì)很好地轉(zhuǎn)化為生物燃料,在水解和預(yù)處理過(guò)程中替代了許多常規(guī)的液體酸。磁性固體酸作為一種復(fù)合型的催化劑,不僅具有固體酸的高活性,而且還具有磁分離特性,在水解過(guò)程中簡(jiǎn)化了分離步驟,節(jié)約了成本。在本文的研究中,采用共沉淀法合成出Fe3O4粒子,然后通過(guò)碳化磺化步驟對(duì)磁性粒子進(jìn)行包裹合成出磁性固體酸Fe3O4/C-SO3H,以催化水解只經(jīng)簡(jiǎn)單處理后生物質(zhì)玉米芯生成的木糖得率為考察目標(biāo)優(yōu)化制備條件,通過(guò)響應(yīng)面法對(duì)磁性固體酸Fe3O4/C-SO3H的四個(gè)制備條件進(jìn)行模擬優(yōu)化。利用FT-IR、XRD、VSM、TG/DTG、BET等手段對(duì)以上最優(yōu)制備條件的磁性固體酸Fe3O4/C-SO3H(Fe3O4、Fe3O4/C)進(jìn)行分析,另對(duì)催化劑的循環(huán)回收及使用作了初步探討。并對(duì)磁性固體酸催化玉米芯水解進(jìn)行優(yōu)化研究及探討催化機(jī)理和過(guò)程,提出磁性固體酸催化水解纖維素及半纖維素的機(jī)理,為磁性固體酸水解木質(zhì)纖維素類生物質(zhì)提供理論基礎(chǔ)。(1)首先以NaOH溶液為沉淀劑、在80℃下反應(yīng)8h的條件下合成出Fe3O4粒子;并以Fe3O4粒子為磁性載體合成出磁性固體酸Fe3O4/C-SO3H,得到的最優(yōu)條件是碳化溫度為450 ℃、碳化時(shí)間為3 h、磺化溫度為100 ℃、磺化時(shí)間為9 h。利用響應(yīng)面法對(duì)磁性固體酸Fe3O4/C-SO3H的四個(gè)制備條件進(jìn)行模擬優(yōu)化得到的最佳工藝是:碳化溫度455 ℃、碳化時(shí)間4.8 h、磺化溫度107 ℃、磺化時(shí)間10.0 h,影響磁性催化劑活性的主次因素為:磺化時(shí)間碳化時(shí)間碳化溫度磺化溫度。(2)通過(guò)多種分析測(cè)試手段對(duì)最優(yōu)制備條件的磁性固體酸催化劑Fe304/C-SO3H(Fe3O4、Fe3O4/C)進(jìn)行分析得出:飽和磁化強(qiáng)度為7.78Am2/kg、比表面積為4.26 m2/g、粒徑約為20 nm、總酸量為1.66 mmol/g及化學(xué)式為CH0.689O0.443S0.021Fe0.124。固體酸催化劑能穩(wěn)定分散在反應(yīng)體系中,在外部磁場(chǎng)的作用能從反應(yīng)體系中快速分離,并重復(fù)使用多次。(3)催化水解玉米芯得到的最佳反應(yīng)條件為反應(yīng)時(shí)間應(yīng)10 h、反應(yīng)溫度140 ℃、催化劑用量1.5g、固液比2:50g/mL(玉米芯含量為0.5g)、木糖得率為51.01%。并總結(jié)了磁性固體酸催化木質(zhì)纖維素的水解過(guò)程和機(jī)理,對(duì)木質(zhì)纖維素選擇性水解產(chǎn)生單糖及催化劑的合成應(yīng)用提供指導(dǎo)。
[Abstract]:Because of the depletion of fossil fuels and the increasing demand for fuels, the development of renewable resources for the production of alternative energy sources and chemicals has become increasingly important. Lignocellulosic biomass can be converted into many products by chemical or biological means, such as biofuels (biodiesel, bio-ethanol and biogas) and chemicals (acetic acid, acetic acid). Acetone and lactic acid, and now some products can replace the application of petroleum. At present, the carbohydrates in lignocellulose are converted into soluble monosaccharides by acid hydrolysis or direct and indirect conversion. The solid acid catalyst has the advantages of high activity, good selectivity, low corrosion, long catalyst life and easy to recycle and reuse. The lignocellulosic biomass can be converted to biofuel very well. In the process of hydrolysis and pretreatment, many conventional liquid acids have been replaced. Magnetic solid acids, as a composite catalyst, not only have the high activity of solid acids. It also has magnetic separation characteristics, simplifies separation steps and saves cost during hydrolysis. In this paper, Fe3O4 particles are synthesized by coprecipitation method. The magnetic solid acid Fe _ 3O _ 4 / C-SO _ 3H was synthesized by carbonation and sulfonation. The optimum preparation conditions were as follows: the xylose yield of biomass corncob after catalytic hydrolysis was simply treated. Four preparation conditions of magnetic solid acid (Fe3O4/C-SO3H) were simulated and optimized by response surface method. The magnetic solid acid Fe3O4 / C-SO3HNFe3O4Fe3O4Fe3O4Fe3O4 / C was analyzed by means of FT-IR, XRDX, TG- / DTGET, etc. In addition, the recycling and utilization of the catalyst were discussed. The mechanism of magnetic solid acid catalyzed hydrolysis of corn cob was studied, and the mechanism of magnetic solid acid catalyzed hydrolysis of cellulose and hemicellulose was put forward. To provide a theoretical basis for magnetic solid acid hydrolysis of lignocellulosic biomass. (1) firstly, Fe3O4 particles were synthesized by using NaOH solution as precipitant and reacting at 80 鈩，

本文編號(hào)：1628648