本文關(guān)鍵詞：基于分子篩制備生物柴油影響研究　出處：《山東理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 生物柴油 動(dòng)力學(xué)模型 改性分子篩 響應(yīng)面 酯化反應(yīng)

【摘要】：本文以油酸與乙醇的酯化反應(yīng)作為探針?lè)磻?yīng),研究分子篩孔結(jié)構(gòu)以及表面疏水性對(duì)分子篩催化制備生物柴油催化性能的影響,并在此基礎(chǔ)上對(duì)分子篩進(jìn)行改性,進(jìn)一步提高分子篩催化性能,此外本文同時(shí)使用不同動(dòng)力學(xué)模型對(duì)酯化反應(yīng)進(jìn)行模擬預(yù)測(cè)并對(duì)不同模型進(jìn)行對(duì)比研究。實(shí)驗(yàn)首先選取不同硅鋁比的微孔型分子篩(BEA型Beta分子篩和MFI型ZSM-5分子篩)以及微孔-介孔復(fù)合分子篩(MFI型ZRP-5分子篩)作為催化劑催化制備生物柴油,采用西勒模數(shù)計(jì)算研究分子篩孔徑對(duì)反應(yīng)過(guò)程中內(nèi)傳質(zhì)阻力的影響。結(jié)果顯示,硅鋁比較高的分子篩催化性能較好,并且在硅鋁比相同時(shí),ZRP-5分子篩在反應(yīng)過(guò)程中內(nèi)傳質(zhì)阻力最小但催化性能最差。通過(guò)對(duì)樣品表征分析與動(dòng)力學(xué)模型推導(dǎo)證明在表面疏水性較弱的ZRP-5分子篩表面,乙醇與油酸存在競(jìng)爭(zhēng)吸附現(xiàn)象,極性較弱的油酸分子較難吸附在分子篩表面,導(dǎo)致分子篩表面油酸覆蓋程度較低,進(jìn)而導(dǎo)致酯化反應(yīng)轉(zhuǎn)化率下降。在所有分子篩樣品中,Beta(50)分子篩催化性能最高,在優(yōu)化反應(yīng)條件下(乙醇油酸摩爾比20:1,反應(yīng)溫度78.0°C,反應(yīng)時(shí)間10.0 h,攪拌速度600 rpm,催化劑用量0.167 meq/g)最高轉(zhuǎn)化率達(dá)到73.6%,且Beta(50)分子篩催化劑重復(fù)使用五次后活性組分Al沒(méi)有明顯流失。實(shí)驗(yàn)進(jìn)一步采用表面包覆接枝方法對(duì)分子篩樣品進(jìn)行改性,制備聚苯乙烯磺酸包覆接枝分子篩。通過(guò)對(duì)樣品分析表征證明,采用包覆接枝方法能夠?qū)⒕郾揭蚁┗撬岱�(wěn)定包覆在分子篩表面,且催化劑重復(fù)使用5次后,聚苯乙烯磺酸仍然能夠包覆在分子篩表面。實(shí)驗(yàn)使用響應(yīng)面法對(duì)反應(yīng)條件進(jìn)行優(yōu)化,在優(yōu)化反應(yīng)條件下一次轉(zhuǎn)化率最高達(dá)到96.4%(優(yōu)化條件包括:反應(yīng)時(shí)間4.1 h,催化劑用量47.8 wt%,乙醇油酸摩爾比15:1)。與分子篩樣品以及苯乙烯系陽(yáng)離子交換樹(shù)脂相比,聚苯乙烯磺酸包覆接枝分子篩能夠顯著提高油酸轉(zhuǎn)化率,并縮短反應(yīng)時(shí)間。
[Abstract]:In this paper, the esterification of oleic acid with ethanol was used as a probe to study the effect of pore structure and surface hydrophobicity of molecular sieve on the catalytic performance of molecular sieve to prepare biodiesel. Further improve the catalytic performance of molecular sieve. In addition, different kinetic models were used to simulate and predict the esterification reaction, and different models were compared. Firstly, microporous molecular sieves with different Si-Al ratios were selected. BEA type Beta molecular sieve and MFI type ZSM-5 molecular sieve) and microporous / mesoporous composite molecular sieve MFI ZRP-5 molecular sieve) were used as catalysts to prepare biodiesel. The influence of molecular sieve pore size on internal mass transfer resistance in the reaction process was studied by using Schiller modulus. The results showed that the molecular sieve with higher Si-Al catalyst had better catalytic performance, and when the ratio of Si to Al was the same. ZRP-5 molecular sieve has the least internal mass transfer resistance but the worst catalytic performance in the reaction process. The characterization analysis and kinetic model analysis of the sample show that the surface hydrophobicity of ZRP-5 molecular sieve surface is weak. There is a competitive adsorption phenomenon between ethanol and oleic acid, and it is difficult for oleic acid molecules with weak polarity to adsorb on the surface of molecular sieve, resulting in low oleic acid coverage on the surface of molecular sieve. Therefore, the conversion of esterification reaction decreased. Among all the molecular sieve samples, the catalytic activity of the zeolite was the highest, and the molar ratio of ethanol to oleic acid was 20: 1 under the optimized reaction conditions. The reaction temperature was 78.0 擄C, the reaction time was 10.0 h, the stirring rate was 600rpm, the amount of catalyst was 0.167meq / g) and the highest conversion was 73.6%. The active component Al was not significantly lost after the catalyst was reused for five times. The surface coating grafting method was further used to modify the molecular sieve samples. Polystyrene sulfonic acid coated molecular sieve was prepared. The results of sample analysis and characterization showed that polystyrene sulfonic acid could be stably coated on the surface of molecular sieve by coating grafting method, and the catalyst was reused for 5 times. Polystyrene sulfonic acid can still be coated on the surface of molecular sieve. Response surface method is used to optimize the reaction conditions. Under the optimized reaction conditions, the maximum conversion rate was 96.4wt% (the optimum conditions were as follows: reaction time 4.1 h, catalyst dosage 47.8 wt%). The molar ratio of ethanol to oleic acid is 15: 1. Compared with the molecular sieve sample and the styrene cationic exchange resin, the graft molecular sieve coated with polystyrene sulfonic acid can significantly increase the conversion of oleic acid and shorten the reaction time.
【學(xué)位授予單位】：山東理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TE667

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相關(guān)期刊論文 前1條

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本文編號(hào)：1423289