本文選題：密度泛函理論　切入點(diǎn)：ONIOM　出處：《物理化學(xué)學(xué)報(bào)》2017年04期

【摘要】：采用"our own-N-layered integrated molecular orbital+molecular mechanics"(ONIOM)和密度泛函理論(DFT)結(jié)合的方法,在5T、12T、104T_9和104T_(12)H-ZSM-5模型中研究了苯和甲醇甲基化的分步和協(xié)同機(jī)理。描述了中間體物種和過(guò)渡態(tài)的結(jié)構(gòu)�？疾炝薍-ZSM-5催化劑Br?nsted(B)酸強(qiáng)度對(duì)苯和甲醇甲基化反應(yīng)機(jī)理的影響。反應(yīng)活化能結(jié)果表明,在B酸強(qiáng)度更強(qiáng)的H-ZSM-5催化劑上,苯和甲醇甲基化反應(yīng)更容易發(fā)生,反應(yīng)活化能更低。隨著B(niǎo)酸強(qiáng)度增強(qiáng),分步機(jī)理的反應(yīng)活化能比協(xié)同機(jī)理的反應(yīng)活化能降低的更多。B酸強(qiáng)度增強(qiáng)對(duì)分步機(jī)理更有利。當(dāng)分步機(jī)理成為主導(dǎo)反應(yīng)路徑時(shí),分步機(jī)理中甲醇脫水步驟生成的甲氧基中間體進(jìn)一步生成大體積烴類的副反應(yīng)會(huì)導(dǎo)致H-ZSM-5催化劑因積炭而失活。合理調(diào)變H-ZSM-5催化劑的酸強(qiáng)度對(duì)提高催化劑的催化活性和穩(wěn)定性有重要意義。
[Abstract]:Using the method of "our own-N-layered integrated molecular orbital molecular mechanics" and density functional theory (DFT), the stepwise and synergistic mechanism of methylation of benzene and methanol was studied in the 5T ~ (12) T ~ (12) T ~ (10 ~ 4) T _ 9 and 104T_(12)H-ZSM-5 model. The structure of intermediate species and transition state was described. The effect of acid strength on the mechanism of methylation of benzene with methanol. The results of activation energy show that the methylation of benzene with methanol is easier and the activation energy of the reaction is lower with the increase of the strength of B acid on the H-ZSM-5 catalyst with higher strength of B acid. The activation energy of the stepwise mechanism is more favorable to the stepwise mechanism than that of the synergistic mechanism. The side reaction of methoxy intermediate produced by methanol dehydration step in the stepwise mechanism will lead to the deactivation of H-ZSM-5 catalyst due to carbon deposition. The modification of acid strength of H-ZSM-5 catalyst can improve the catalytic activity of the catalyst. Sex and stability are of great significance.
【作者單位】： 遼寧科技學(xué)院冶金工程學(xué)院;大連理工大學(xué)化工學(xué)院精細(xì)化工國(guó)家重點(diǎn)實(shí)驗(yàn)室PSU-DUT聯(lián)合能源研究中心;賓夕法尼亞州立大學(xué)能源與礦物工程系能源研究所PSU-DUT聯(lián)合能源研究中心;
【基金】：遼寧省教育廳科學(xué)研究一般項(xiàng)目基金(L2014503) 遼寧省自然科學(xué)基金項(xiàng)目(201602403) 遼寧科技學(xué)院博士科研啟動(dòng)基金項(xiàng)目(1406B08) 國(guó)家自然科學(xué)基金項(xiàng)目(21503027)資助~~
【分類號(hào)】：O643.36

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