共查询到18条相似文献,搜索用时 93 毫秒
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采用不同硅铝比的介孔分子筛(Al-SBA-15)作为载体负载不同量的铜元素作为催化剂(CuO/AlSBA-15),通过小角X射线衍射、氮气吸附脱附等温线表征其结构性质,并以苯酚羟基化的反应为模型反应考察了材料的催化性能。研究发现,高的铜负载量不利于介孔材料结构的保持,在较低的铜负载量(3%)的情况下就可以使苯酚羟基化达到61.2%的高转化率。通过对Al-SBA-15和SBA-15作为载体的催化剂的循环套用分析,发现Al-SBA-15作为载体经过5次套用之后依然保持着57.9%的高转化率,而SBA-15经5次套用后的转化率仅有43.6%。这种结果应该得益于载体中的铝元素增加了材料表面的电荷,使铜离子与载体的相互作用加强,在循环套用中的铜离子在材料表面的分散更均匀。 相似文献
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首次在三相条件下,在Beta沸石催化剂上研究了苯酚与异丁烯烷基化合成对叔丁基苯酚和2,4-二叔丁基苯酚。通过对Hbeta沸石高温焙烧和吡啶中毒试验研究了烷基化反应活性和选择性的变化规律;用NH3-TPD和Py-IR测定了试样的酸量和酸种类,结果表明Hbeta沸石具有很好的烷基化活性,苯酚的转化率可达92%,经1123K焙烧后苯酚转化率为88%,对叔丁基苯酚和2,4-二叔丁基苯酚的选择性分别为70~75%和14~20%,中等强度的Brnsted酸是苯酚与异丁烯烷基化反应的活性中心。粘合剂含量低于30%对烷基化活性基本无影响 相似文献
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以2,4-二甲基-6-叔丁基苯酚、多聚甲醛和三氯氧磷为原料,在四氯化碳溶剂中合成了6-叔丁基-3-氯甲基-2,4-二甲基苯酚并确定较佳的工艺条件,分别考察了物料配比、反应温度、反应时间和相转移催化剂用量对反应收率的影响。确定较佳工艺为:在四氯化碳溶剂中,反应温度为40℃,2,4-二甲基-6-叔丁基苯酚用量为60 g,多聚甲醛12 g,浓盐酸30 g,相转移催化剂4 g,三氯氧磷40 g。在上述条件下,6-叔丁基-3-氯甲基-2,4-二甲基苯酚的收率为95%,纯度>99%(HPLC面积归一化法),产品结构经IR、MS和~1H-NMR表征。 相似文献
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Zahra MEHRABAN Faezeh FARZANEH Mehdi GHANDI Alireza ABBASI 《催化学报》2007,28(4):357-363
以异丙醇铝、硅酸四乙酯和十六烷基三甲基溴化胺为原料,以乙酰丙酮为螯合剂,采用溶胶-凝胶法合成了硅铝比分别为25,50,100和150的介孔硅铝分子筛,并用其催化苯酚与1-辛烯的液相烷基化反应.X射线衍射、N2吸附、高分辨透射电镜及27Al核磁共振光谱表征结果表明,该介孔分子筛具有蠕虫状骨架结构.在160℃时,硅铝比为25的介孔硅铝分子筛催化剂上苯酚可以完全转化为单烷基苯酚. 相似文献
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用甲基叔丁基甲醚对苯酚叔丁基化的反应研究 总被引:1,自引:0,他引:1
目前我国生产对叔丁基苯酚的方法通常以酚类为原料,烯烃或醚类为烷基化试 剂,其中异丁烯是主要烷基化试剂,但异丁烯在储存、运输等方面存在着一定的弊 端.采用直接以甲基叔丁基甲醚为烷基化试剂,研究了苯酚与甲基叔丁基甲醚的烷 基化反应.并对各影响因素进行了讨论,其中催化剂用量和原料比对反应影响最大 ,温度次之,反应时间影响最小.实验中得出了制备反应的最佳条件;苯酚转化率 大于85%,对叔丁基苯酚产率为78%,得到较理想产率.并与以异丁烯为烷基化试 剂进行了比较,具有成本低、流程短、操作简便、安全等特点,应用前景非常好. 相似文献
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Kandan VENKATACHALAM Pitchai VISUVAMITHIRAN Balachandran SUNDARAVEL Muthiapillai PALANICHAMY Velayutham MURUGESAN 《催化学报》2012,(3):478-486
Al-MCM-48 molecular sieves (Si/Al molar ratios = 25, 50, 75, and 100) were synthesized hydrothermally using cetyltrimethyl-ammonium bromide as the structure directing template. The orderly arrangement of mesopores was evident from the low angle X-ray diffraction patterns and transmission electron microscopy images. The catalytic performance of the materials was evaluated in the vapor phase isopropylation of phenol with isopropyl acetate. Phenol conversion decreased with the increase in the Si/Al ratio of the catalysts. The major reaction product was 4-isopropyl phenol with 78% selectivity. The delocalization of phenolic oxygen electron pair over the aromatic ring promoted para-selective alkylation. Such delocalization could be aided by the hydrophilic surface of the molecular sieves. Although an ester was used as the alkylating agent, phenyl isopropyl ether was not formed in the reaction. 相似文献
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Novel phosphazene cyclomatrix network polymers were synthesized via the nucleophilic displacement of activated nitro groups
of tri(4-nitrophenoxy)tri(phenoxy)cyclotriphosphazene and hexa(p-nitrophenoxy) cyclotriphosphazene with hydroxyls of bisphenol A. Both monomers and polymers were characterized by Fourier
transform infrared spectroscopy, 1H nuclear magnetic resonance, and elemental analysis measurements, and their structures were identified. Thermal properties
of polymers were investigated using dynamic thermogravimetric analysis in air. The results demonstrated that both cyclomatrix
phosphazene polymers 4 and 6 were of excellent thermal stability, and their char yields in air at 800°C were 45.1 and 43.2%, respectively. According to
combustion phenomenon, polymer 4 was supposed to be processed with a good flame-retardant property because of its excellent crosslinked structure during pyrolysis
or combustion. However, polymer 6 yielded the opposite result.
Translated from the Journal of Beijing University of Chemical Technology, 2005, 32(2) (in Chinese)
This study was supported by the National High Technology Research and Development Foundation (2002AADF3202) 相似文献
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Highly regiospecific mononitration of phenol and substituted phenols was accomplished employing a metal nitrate and a catalytic amount of KHSO4 in acetonitrile. An exclusive ortho‐selectivity was observed with excellent yields. A variety of metal nitrates were used to obtain o‐nitrophenols exclusively in good to excellent yields. The use of KHSO4 is key for the selectivity observed. 相似文献
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地面水中微量2,4-二硝基苯酚测定方法的探讨 总被引:5,自引:0,他引:5
崔玲君 《广东微量元素科学》1999,6(11):45-47
提出了一种地面水中微量2,4-二硝基苯酚测定方法,讨论了其实验条件。结果表明,该法简单,灵敏度高。 相似文献
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Tonge L. Y. Yazaki Y. Blicblau A. S. 《Journal of Thermal Analysis and Calorimetry》1999,56(3):1347-1352
The self-condensation reactions of 2- and 4-mono-methylol phenols (2-MMP and 4-MMP), in the presence of varying concentrations
of NaOH, have been studied by differential scanning calorimetry (DSC). The reaction exotherms were analysed to derive the
activation energy, Ea, and the heat of reaction, HT, for the condensation reactions. In the case of 2-MMP an increase in NaOH:2-MMP molar ratio caused an increased in Ea and a decrease in HT up to a molar ratio of 0.6:1. However, for 4-MMP, an increase in NaOH concentration caused an increase in Ea up to a molar ratio of 0.3:1 beyond which there appeared to be no further effect. The presence of NaOH had no effect on HT for this compound. The results suggest that in the range of NaOH concentration used the effect of NaOH was substantially
greater on 2-MMP compared to 4-MMP.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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《合成通讯》2012,42(1):112-122
AbstractLewis acid ZnCl2 promoted cyclization protocol to 4H-chromenes is accomplished, using readily available phenols and acetophenones as starting materials. Interestingly, the process is feasible under the solvent free environment. Synthesis of a variety of 4H-chromenes have been accomplished using this strategy. In addition, this concept is extended to the synthesis of ortho-benzylphenols by treating phenols either with styrenes or secondary benzylic alcohols. 相似文献