【作者】 王媛媛；

【导师】 朱明乔；

【作者基本信息】 浙江大学 ， 工程（专业学位）， 2020， 硕士

【摘要】 ε-己内酯是一种优良的有机合成中间体,在医学、环境、化工等领域均有应用。工业生产中常用过氧酸来氧化环己酮制备ε-己内酯,但由于成本高、收率低和原料储存危险等原因需要被替代。H2O2、O2/醛类是目前较为合适的氧化剂,且研发高效的催化剂来提高反应效率已成为重要方向。本文分别以双氧水氧化和氧气/醛共氧化环己酮制ε-己内酯作为性能评价实验,重点探究对体系具有高效催化作用的双金属氧化物催化剂。研究和分析了催化剂的制备、表征、催化性能以及反应条件对环己酮Baeyer-Villiger(B-V)氧化反应的影响,结合论述内容得出以下主要结论:首先,以Mg(Ⅱ)和Sn(Ⅳ)为活性中心,制备不同镁和锡摩尔比例的双金属氧化物催化剂,实验筛选得到较优投料摩尔比为2:1。分别采用共沉淀法和水热法制备不同模板剂修饰的催化剂Mg0.67Sn0.33-N-T和Mg0.67Sn0.33-N/Na-T(H)。催化剂通过X射线衍射(XRD)、扫描电子显微镜(SEM)、N2吸附-脱附等手段进行表征,结果显示模板剂的加入对催化剂形貌、晶相、比表面积等结构性能均有影响,能够提高催化剂稳定性。其中Mg0.67Sn0.33-N-CTAC在双氧水氧化环己酮反应中显示最优催化性能和较少回收损失。优化之后的反应条件为:催化剂0.28g,环己酮 12mmol,H2O2(30wt%)96mmol,乙腈 10 mL,75℃,6h,环己酮转化率达89.92%,ε-己内酯选择性为91.20%。其次,通过O2/苯甲醛共氧化环己酮反应,从多种单金属、双金属氧化物以及分子筛负载型催化剂中选出Ce和Fe为适宜的催化中心;以铈铁摩尔比为3:1为定值,探究共沉淀法、溶胶凝胶法、氢气还原法、直接混烧法制备的催化剂催化性能;选择采用共沉淀法,改变铈铁投料摩尔比制得一系列催化剂Ce/Fe(a:b)-600,通过环己酮氧化实验得出较适比例为2:1;在此基础上制不同焙烧温度催化剂Ce/Fe(2:1)-T,结合XRD、N2吸附-脱附、X射线光电子能谱(XPS)等手段的表征结果可知CeO2和Fe2O3之间存在协同作用。Ce/Fe(2:1)-500具有相对最高的表面氧浓度,有利于苯甲醛和环己酮的活化,在氧气/苯甲醛共氧化环己酮反应中展现最优催化效果。筛选得出较适反应条件为:催化剂50mg,环己酮12mmol,苯甲醛 24mmol,O2 10mL/min,1,2-二氯乙烷(DCE)20mL,反应温度 45℃,时间4h,环己酮转化率99.20%,ε-己内酯选择性99.93%,苯甲醛转化率97.22%,苯甲酸选择性99.32%,催化剂循环使用4次没有明显活性下降。接着,将上述催化剂Ce/F e(a:b)-600和催化剂Ce/Fe(1:1)-T用于催化O2/异丁醛共氧化环己酮制ε-己内酯反应,筛选得到Ce/Fe(1:1)-500为最适催化剂。对催化剂用量、反应温度、时间、醛酮比等条件进行探究,得到适宜的反应条件为:催化剂 50mg,环己酮 12mmol,异丁醛18mmol,O2 15mL/min,DCE 15mL,反应温度45℃,时间1.5h,环己酮转化率35.60%,ε-己内酯选择性99.91%,异丁醛转化率99.94%,异丁酸选择性91.90%,催化剂循环使用5次仍保持较高活性。最后,对氧气/异丁醛氧化环己酮年产1000吨ε-己内酯工艺进行放大方案设计,可为以后实际生产设计提供一定参考。更多还原

【Abstract】 ε-Caprolactone is an excellent intermediate in organic synthesis,which has been used in the fields of medicine,environment,chemical industry and so on.Peroxy acid is commonly used to oxidize cyclohexanone to produce ε-caprolactone in industrial production,but it needs to be replaced because of high cost,low yield and risk of raw materials storage.H2O2 and O2/aldehydes are suitable oxidants at present,and it has been an important direction to develop efficient catalysts for improving reaction efficiency.In this paper,the oxidation of cyclohexanone to ε-caprolactone with H2O2 and O2/aldehyde were used as performance evaluation experiments respectively,and the bimetallic oxide catalyst with high catalytic effect on the system was mainly explored.The preparation,characterization,catalytic performance and effects of reaction conditions on the Baeyer-Villiger(B-V)oxidation of cyclohexanone were studied and analyzed.The main conclusions were as follows:First of all,bimetallic oxide catalysts with different molar ratios of magnesium to tin were prepared with Mg(Ⅱ)and Sn(Ⅳ)as active centers,the optimum molar ratio was 2:1.The template modifi ed catalyst Mg0.67Sn0.33-N-T and Mg0.67Sn0.33-N/Na-T(H)with different templates was obtained by coprecipitation and hydrothermal method,respectively.The results of X-ray-diffraction(XRD),scanning electron microscope(SEM)and N2 adsorption-desorption,showed that templates can improve the stability of the catalyst by affecting the structural properties such as morphology,crystal phase and specific surface area of the catalyst.Mg0.67Sn0.33-N-CTAC showed best catalytic performance and less recovery loss in the oxidation of cyclohexanone.The optimized reaction conditions were as follows:catalyst 0.28 g,cyclohexanone 12 mmol,96 mmol H2O2(30wt%),acetonitrile 10 mL,75℃,6 h,the conversion of cyclohexanone was 89.92%,and the selectivity of ε-caprolactone was 91.20%.Secondly,through the oxidation of cyclohexanone with O2/benzaldehyde,Ce and Fe were selected as the suitable catalytic centers from a variety of monometallic,bimetallic oxides and molecular sieve supported catalysts;Taking the molar ratio of Ce to Fe at 3:1,the different properties of the catalysts prepared by coprecipitation,sol-gel,hydrogen reduction and direct mixed combustion method were studied;A series of catalysts Ce/Fe(a:b)-600 with diffierent molar ratio of Ce to Fe were obtained,the optimum ratio was 2:1 according to experiments;Catalysts Ce/Fe(2:1)-T was prepared at different calcination temperature,it was found that there was a synergistic effect between CeO2 and Fe2O3 combined with the characterization results of XRD,N2 adsorption-desorption and X-ray photoelectron spectroscopy(XPS).Ce/Fe(2:1)-500 had the highest surface oxygen concentration,which was beneficial to activation of benzaldehyde and cyclohexanone,showing the best catalytic performance.The optimum reaction conditions were as follows:catalyst 50 mg,cyclohexanone 12 mmol,benzaldehyde 24 mmol,O2 10 mL/min,1,2-dichloroethane(DCE)20mL,reaction temperature 45℃,reaction time 4 h,conversion of cyclohexanone 99.20%,selectivity of ε-caprolactone 99.93%,the conversion of benzaldehyde was 97.22%and the selectivity of benzoic acid was 99.32%.There was no obvious change in the activity of the catalyst when it was recycled for 4 times.Then,the above catalyst Ce/Fe(a:b)-600 and Ce/Fe(1:1)-T was used to catalyze the oxidation of cyclohexanone to ε-caprolactone with O2/isobutyraldehyde,Ce/Fe(1:1)-500 was selected as the optimum catalyst.The effects of the amount of catalyst,reaction temperature,reaction time and the ratio of aldehyde to ketone were investigated and suitable reaction conditions are as follows:catalyst 50 mg,cyclohexanone 12 mmol,isobutyraldehyde 18 mmol,O2 15 mL/min,DCE 15 mL,reaction temperature 45℃,reaction time 1.5 h.The conversion of cyclohexanone and isobutyraldehyde was 35.60%and 99.94%,the selectivity of ε-caprolactone and isobutyric acid was 99.91%and 91.90%.Finally,the scale-up design of the oxygen/isobutyraldehyde co-oxidation of cyclohexanone to ε-caprolactone with an output of 1000 t/a was proposed,which can provide some reference for the actual production design in the future.更多还原