Thermal Hydrodealkylation of Alkylbenzenes in the Presence of Methanol or Water

甲醇或水存在下烷基苯的热加氢脱烷基化

• 批准号: 05453128
• 负责人: ITOH Hironori
• 金额: $ 4.74万
• 依托单位: HOKKAIDO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1993
• 资助国家: 日本
• 起止时间: 1993 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05453128/
• 关键词: Themolysis; Dealkylation; Hydrogen of methanol decomposition; Alkylbenzene; Alkylphenol

The thermal hydrodealkylation of alkylbenzenes and alkylphenols were carried out in hydrogen in the presence and absence of methanol. The methanol solution of alkylbenzenes and alkylphenols was injected into the reactor at 850 C for 1 h. For the reaction in the presence of methanol in H2, the yields of benzene increased, and the condensed products and carbon decreased compared with the results of the reaction in H2 without methanol. For the reaction of xylenes, the benzene yield was somewhat lower and the toluene yield was higher than those of the reaction of ethylbenzene. Therefore, the C2-fragment or C2-side chain should play an important role in producing condensed aromatics such as naphthalene, indene, etc.In the reactions of cresols and ethylphenols at 850 C in the presence or absence of methanol, benzene was the most abundant product in all the reactions. Dehydroxylation also occurred in addition to hydtodealkylation. For the reaction in H2 with methanol, the benzene yield increa … More sed for o-cresol and o-ethylphenol, and decreased for m-cresol and m-ethylphenol while the toluene yield slightly increased compared with the results from the reactions without methanol.In order to examine the reaction mechanism, the reaction of dueterated toluene in the presence of methanol was carried out at 750 C.Benzene having no deuterium and toluene having 1-to 5-deutrium were detected after the reaction. These results suggest that the benzyl radical produced initially from thermal cracking of toluene may react with hydrogen radical from methanol decomposition to produce phenyl radical which subtracts from hydrogen of toluene or hydrogen to produce benzene.In the presence of water the reaction did not accelerate effectively because of no decomposition of water.Thermal hydrodealkylation and dehydroxylation reactions in hydrogen in the presence of methanol were confirmed by the reaction of alkylbenzenes and alkylphenols.It is suggested that a suitable catalyst may lower the reaction temperature and the amount of condensed products. Less

在甲醇存在和不存在的情况下，对烷基苯和烷基酚进行了热加氢脱烷基反应。将烷基苯和烷基酚的甲醇溶液在850℃下注入反应器，反应1 h。与不含甲醇的H2反应相比，有甲醇的H2反应中苯的产率提高，缩合产物和碳的产率降低。对于二甲苯的反应，苯的产率略低于乙苯的反应，甲苯的产率略高于乙苯的反应。因此，在生成萘、茚等缩合芳烃时，c2片段或c2侧链应起重要作用。在850℃下甲酚和乙酚在有或无甲醇条件下的反应中，苯是所有反应中含量最多的产物。除氢化脱烷基外，还发生去羟基化反应。与无甲醇反应相比，邻甲酚和邻乙基苯酚的产率提高，间甲酚和间乙基苯酚的产率降低，而甲苯的产率略有提高。为了考察反应机理，在750℃的温度下进行了甲醇存在下的甲苯脱水反应，反应后检测了不含氘的苯和含有1- 5-氘的甲苯。这些结果表明，甲苯热裂解产生的苯自由基可能与甲醇分解产生的氢自由基反应生成苯自由基，苯自由基由甲苯的氢或氢减去生成苯。在有水的情况下，由于没有水的分解，反应不能有效地加速。通过烷基苯和烷基酚的反应，证实了在甲醇存在下，氢的热加氢脱烷基和脱羟基反应。选择合适的催化剂可以降低反应温度和缩合产物的数量。少