【作者】 祝明霞；

【导师】 袁友珠；

【作者基本信息】 厦门大学 ， 物理化学， 2008， 博士

【摘要】 本论文以烷基芳烃及醇类的液相选择氧化为目标反应,研究了多核铜配合物和官能团化SBA-15固定化铜配合物等催化剂的合成、表征和催化性能,取得以下主要结果。通过改进合成方法,从硝酸铜原料和三乙醇胺（标记为H₃tea）配体出发,合成了四种多核铜配合物,即双核铜配合物[Cu₂（H₂tea）₂（C₆H₅COO）₂]·2H₂O（标记为Cul）,三核铜配合物[Cu₃（H₂tea）₂（4-OC₆H₄COO）₂（H₂O）]·4H₂O（标记为Cu2）,四核铜配合物[O（?）Cu₄（tea）₄（BOH）₄]·[BF₄]2（标记为Cu3）和多核铜配合物[Cu₂（H₂tea）₂{μ-C₆H₄（COO）₂-1,4}]₄·2nH₂O（标记为Cu4）,这四种铜配合物的结构得到了元素分析和红外结果的确认。在此基础上,研究了所得到的多核铜配合物对C₂以上烷基苯的选择氧化催化性能。实验结果表明:（ⅰ）在温和条件和叔丁基过氧化氢（TBHP）存在下,四个多核铜配合物均可选择性的使C₂以上烷基苯以较高转化率和选择性转化成相应的酮;（ⅱ）受中心金属Cu（Ⅱ）在配合物中的配位方式以及配合物在催化反应体系中溶解性的影响,各配合物在TBHP存在下对烷基芳烃选择氧化反应的催化性能相差较大,其中,四核铜配合物Cu3比其它三种配合物表现出更高的活性和选择性。在TBHP存在下,Cu3催化剂对乙苯选择性氧化主产物苯乙酮的最高选择性大于90%,最高收率接近60%;（ⅲ）芳烃上取代烷基的结构以及其它取代基的电子效应对催化性能有较大的影响,吸电子取代基使转化率下降。实验结果还表明,在TBHP或O₂/TEMPO存在下,各配合物催化剂均能使各种取代芳香伯/仲醇以及杂环醇等以不同程度的转化率和选择性转化成相应的醛或酮,其中,配合物Cu3在O₂/TEMPO存在下可使苯甲醇和烯丙醇等以较高转化率和近100%的选择性转化成相应的醛,而对其它芳香醇和脂肪伯/仲醇等的催化性能则较差;在TBHP存在下,配合物Cu3则可使1-苯乙醇和其它仲醇以较高转化率和近100%的选择性转化为相应的酮,但对各类其它伯醇选择氧化的性能相对较差。两种条件下底物的电子效应和位阻效应对Cu3配合物催化剂性能的影响也不尽相同。在上述研究的基础上,进一步制备了双吡啶官能团化及其固定化铜配合物催化剂SBA-15-bipy-Cu,并考察了该固定化铜配合物催化剂对乙苯选择氧化催化性能。多种表征结果表明,介孔分子筛经有机官能团修饰并固载Cu后,保持分子筛特有的骨架和规整孔道结构,可提供反应分子扩散与反应的适度空间。催化反应的实验结果表明,在乙苯氧化研究中,存在于分子筛表面的铜吡啶胺配合物结构稳定,在TBHP存在下表现出较好的乙苯选择氧化反应催化活性和苯乙酮的选择性,并在多次催化剂的循环使用过程中,催化活性和选择性无明显下降趋势。更多还原

【Abstract】 This dissertation has set the selective oxidation of alkylaromatics and alcohols as the object of study,focusing on the synthesis,characterization and catalytic performance of multinuclear copper complexes and organo-functionalized SBA-15 encapsulated copper complexes.The main achievements are summarized as followings.By modifying the synthetic methods in literature,four multinuclear copper complexes,that is,dinuclear[Cu₂（H₂tea）₂（C₆H₅COO）₂]·2H₂O（designated as Cul）, trinuclear[Cu₃（H₂tea）₂（4-OC₆H₄COO）₂（H₂O）]·4H₂O（designated as Cu₂）,tetranuclear [O（?）Cu₄（tea）₄（BOH）₄]·[BF₄]₂（designated as Cu3）,polynuclear[Cu₂（H₂tea）₂ {μ-C₆H₄（COO）₂-1,4}]_n·2nH₂O（designated as Cu4）,have been synthesized.Their structures have been confirmed by means of FT-IR spectroscopic studies and elemental analyses.These complexes have been employed as catalysts for the selective oxidation of ethylbenzene and other alkylaromatics using tert-BuOOH（TBHP）.Several conclusions have been obtained:（ⅰ） The four complexes showed significant activity for the selective oxidation of alkylaromatics with alkyl substitute groups larger than C2 in the presence of TBHP under mild conditions,affording corresponding ketones as the major products.（ⅱ） The catalytic performances of the complexes are different from each other,due to the different coordinations and solubility.Among them,the acetophenone with a selectivity higher than 90%and a yield at about 60%can be achieved with Cu3 catalyst using TBHP.（ⅲ） The alkyl structures in alkylaromatics and the electron effect of their substitute groups were crucial for the catalytic results. Lower conversion was obtained when the alkylaromatics have electron withdrawing substitute groups.Moreover,the selective oxidation of primary and secondary alcohols to corresponding carbonyl compounds with the multinuclear copper complexes Cul-Cu4 as catalysts have been conducted using TBHP and O₂/TEMPO,respectively.Among them,the copper complex Cu3 showed the best performance.On the performances of the two classes of oxidants,benzylic and heterocyclic alcohols could be effectively oxidized to carbonyl compounds.Specifically,the secondary alcohols could be effectively oxidized to ketones with excellent selectivity up to 100%in the presence of TBHP and the allylic alcohols could be effectively oxidized to aldehydes in the presence of O₂/TEMPO system.Electronic and steric effects are different from each other on the two classes of oxidative systems due to different reaction mechanisms.Next,a new class of heterogenized Cu complexes catalysts were prepared by anchoring Cu（OAc）₂ into the mesoporous channels of the bipyridylamine-modified SAB-15 and applied to the selective oxidation of ethylbenzene.Evidences from the experiments revealed that the mesoporous silicas retained their skeletion and ordered mesoporous structures after the organo-functionalization and Cu encapsulation.The remained channels were enough for the diffusion and reaction of substrate.The catalysts exhibited high efficiency for the selective oxidation of ethylbenzene to acetophenone using TBHP under mild conditions.The results also showed that the bipyridylamine-Cu complex species formed at the support surfaces were structurally stable.The resulting catalyst could be reused several times with negligible losses in activity and selectivity.更多还原