负载杂多酸(盐)的表征及其在苹果酯合成反应中的催化性能

用浸渍法制备了一系列负载型磷钨酸及其铯盐催化剂,载体包括超稳Y沸石（USY）、脱铝超稳Y沸石（DUSY）、SiO₂和SBA-15,测定了催化剂的比表面积和酸强度,并在乙酰乙酸乙酯与乙二醇液相缩合制取苹果酯反应中考察了催化剂的性能.结果表明,这些负载型杂多化合物催化剂都表现出较高的催化活性.然而,催化剂在水中的溶脱性能实验表明,负载型磷钨酸催化剂存在严重的活性组分流失现象,不能重复使用,而DUSY负载的磷钨酸铯盐催化剂不仅表现出较高的催化活性,而且显示出较好的重复使用性能.在优化的反应条件下30% (质量分数) Cs_2.5H_0.5PW/DUSY催化剂上乙酰乙酸乙酯的转化率可达98.7%,苹果酯的选择性大于97%.     

脱铝超稳Y分子筛负载磷钨酸铯催化水解乙酸甲酯

采用两步浸渍法制备脱铝超稳Y分子筛(DUSY)负载磷钨酸铯(Cs_(2.5)PW)催化剂,用X射线衍射(XRD)、N_2低温吸附-脱附技术(BET)、傅立叶红外光谱(FT-IR)、扫描电镜(SEM)对催化剂进行表征,并考察了USY脱铝及负载量对DUSY/Cs_(2.5)PW在乙酸甲酯水解反应中催化剂性能的影响。结果表明,以DUSY为载体,Cs_(2.5)PW负载量为10%时,Cs_(2.5)PW高度分散,且保持了原有的Keggin结构,催化剂表现出较高的乙酸甲酯水解反应活性,而以USY为载体的催化剂活性低。在反应温度为328 K下,反应2 h,乙酸甲酯水解率为18.70%。催化剂重复使用6次后,乙酸甲酯水解率为15.56%,表明催化剂具有较好的稳定性。     

乙酰乙酸乙酯与乙二醇在活性炭负载磷钨酸催化剂上合反应

表面活性剂处理的活性炭（C）过量浸渍负载磷钨杂多酸（PW）制备活性炭负载磷钨酸催化剂（PW／c）；氨气程序升温脱咐对催化剂酸性质表征，结果显示，负载质量分数为30％，催化剂30％PW／C具有最大酸量。反应测试表明，磷钨酸负载量为30％时催化剂具有最大活性，苹果酯收率为87．5％，适宜的原料配比。（乙酰乙酸乙酯）：n（乙二醇）=1：1.5，最佳反应温度80℃，最佳反应时间30min，表面活性剂处理过的催化剂连续使用9次，苹果酯的收率保持在85％以上。     

乙酰乙酸乙酯与乙二醇在活性炭负载磷钨酸催化剂上缩合反应

表面活性剂处理的活性炭(C)过量浸渍负载磷钨杂多酸(PW)制备活性炭负载磷钨酸催化剂(PW/C);氨气程序升温脱咐对催化剂酸性质表征,结果显示,负载质量分数为30%,催化剂30%PW/C具有最大酸量。反应测试表明,磷钨酸负载量为30%时催化剂具有最大活性,苹果酯收率为87.5%,适宜的原料配比n(乙酰乙酸乙酯)∶n(乙二醇)=1∶1.5,最佳反应温度80℃,最佳反应时间30 m in,表面活性剂处理过的催化剂连续使用9次,苹果酯的收率保持在85%以上。     

硅胶负载磷钨酸催化乙酰乙酸乙酯与乙二醇缩合

采用溶胶-凝胶法制备了一系列硅胶负载磷钨酸催化剂,采用X射线衍射(XRD)、低温N2吸附-脱附和NH3-程序升温脱附(NH3-TPD)实验对催化剂进行了表征,并考察了该系列催化剂用于乙酰乙酸乙酯与乙二醇缩合生成苹果酯的催化性能.结果表明:负载量为40%时,磷钨酸(PW)在硅胶表面处于临界分散状态,并具有规则的孔道结构.比表面积为187 m2/g,具有较高的酸量;在乙酰乙酸乙酯与乙二醇的物质的量之比为1:1.3,反应温度353 K,反应时间30 min条件下,乙酰乙酸乙酯转化率为96.8%,苹果酯选择性为98.5%;该催化剂的稳定性好,反应15次后,乙酰乙酸乙酯转化率为93.1%,苹果酯选择性保持在98%以上.     

HMCM-22分子筛负载磷钨酸催化合成聚甲醛二甲醚

为提高HMCM-22催化剂的酸性,增强其催化聚甲醛二甲醚(DMMn)合成反应活性,通过在HMCM-22分子筛上负载磷钨酸(PW)来增强HMCM-22催化剂的酸性,并以制得的PW/HMCM-22为催化剂,甲醇和三聚甲醛为原料,对聚甲醛二甲醚的合成反应进行了研究。考察了磷钨酸的负载量、焙烧温度和焙烧时间对催化性能的影响。结果表明,当磷钨酸负载量为总催化剂质量的30%,焙烧温度为300℃,焙烧时间为4 h的条件下,PW/HMCM-22催化剂的催化活性较高,三聚甲醛转化率和DMM2~8选择性分别达到了87.12%和54.84%。催化剂循环使用五次后,其活性基本没变化,表明该催化剂的稳定性能很好。     

SiO2负载磷钨酸铯盐催化剂上香兰素与1，2-丙二醇的缩合反应

制备一系列硅胶(SiO2)负载的磷钨酸铯盐催化剂,将其用于香兰素与1,2-丙二醇的缩合反应,合成香兰素丙二醇缩醛,考察催化剂中Cs+取代数、磷钨酸铯盐负载量、催化剂用量、1,2-丙二醇与香兰素摩尔比及反应时间对缩合反应的影响.结果表明:磷钨酸铯盐的Cs+取代数为2.5、负载量为40%时催化剂活性最高;在反应温度368 K、n(1,2-丙二醇)/n(香兰素)=2.4、催化剂用量占反应体系质量分数1.5%、带水剂苯的用量30 mL、回流反应3 h的条件下,香兰素的转化率达到86.6%,香兰素丙二醇缩醛的选择性为100%.     

HM负载磷钨酸催化合成对叔丁基甲苯的研究

以HM沸石分子筛负载磷钨酸(PW)作为催化剂,在100 mL高压釜反应器中进行甲苯与叔丁醇合成对叔丁基甲苯的烷基化反应。考察不同磷钨酸负载量对甲苯与叔丁醇烷基化反应的影响,并用XRD、TG-DSC和NH3-TPD手段对不同负载量催化剂进行了表征,并在反应中考察了他们的催化性能。结果表明,中低负载量的磷钨酸均匀分散于HM表面,当磷钨酸的负载量为25%时,磷钨酸在HM表面高度分散呈现较高活性,催化剂的焙烧温度为350℃。采用25%PW/HM作为催化剂,研究各种反应条件对催化剂性能的影响,在适宜的反应条件下,即反应温度为160℃,叔丁醇与甲苯摩尔比为3,初始压力为0.6 MPa,催化剂的质量分数为20%时,甲苯的转化率为36.3%,对叔丁基甲苯的选择性为82.1%。     

活性炭负载磷钨酸催化合成乙酸苄酯

采用杂多化合物为催化剂,以磷钨酸(PW12)为活性组分,活性炭为载体,用浸渍法和回流吸附法制备出一系列的负载型PW12/C催化剂,并将其用于苯甲醇和冰乙酸合成乙酸苄酯的过程。通过考察酯化率的影响因素,得出PW12/C催化合成乙酸苄酯的较佳工艺条件为:苯甲醇与冰乙酸的摩尔比为1∶2.5,催化剂用量为反应物总量的2.54%,带水剂甲苯10.0 mL,反应时间2.0 h。在此条件下,酯化产率可达90%以上。该催化剂经回收处理后重复使用效果好。     

硅胶负载磷钨酸催化剂上金刚烷的制备

采用过量浸渍法制备了一系列硅胶（SiO2）负载磷钨酸（PW）催化剂,考察了催化剂在桥式四氢双环戊二烯（endo-TCD）异构化制备金刚烷反应中的催化性能,并采用XRD、N2吸附和NH3-TPD等手段对催化剂的物化性质进行了表征。结果表明,当PW负载量为40%时,PW仍能在SiO2表面高度分散;随着PW负载量的增加,催化剂的酸量增加,负载量为40%时酸量最大,负载量进一步增大,酸量下降,40% PW/SiO2表现出最高的催化活性。采用40% PW/SiO2为催化剂,考察了各种反应条件对催化性能的影响。实验结果发现,适宜的反应条件为：催化剂活化温度200℃,反应温度260℃,反应时间3h,初始压力1.1MPa。当催化剂与原料的质量比为0.7,溶剂环己烷与原料的摩尔比为5.0时,endo-TCD的转化率达到99.5%,金刚烷的收率达到24.7%。     

负载型Cs2.5H0.5PW12O40醚化催化剂的制备与催化性能

制备了负载型磷钨酸铯 (Cs2 5H0 5PW1 2 O4 0 )催化剂 ,考察了载体种类、载体性质、制备方法和制备条件对催化剂性能的影响 ,对制备的催化剂进行了表征 ,并考察了负载型Cs2 5H0 5PW1 2 O4 0 作为醚化催化剂的催化活性 结果表明 ,大孔硅胶是Cs2 5H0 5PW1 2 O4 0 的适宜载体 ,硅胶的钠含量越低制备的Cs2 5H0 5PW1 2 O4 0 SiO2 催化剂的活性越高 .采用一步法和二步法制备的Cs2 5H0 5PW1 2 O4 0 SiO2 催化剂均具有较强的酸性、催化活性以及良好的稳定性 ,可以替代液体酸和阳离子交换树脂 ,成为一种环境友好的固体酸催化剂     

One-pot hydrothermal preparation of SBA-15 supported Keggin-type 12-tungstophosphoric heteropolyacid mesoporous material and its bifunctional catalytic performance

In this work, a series of 12-tungstophosphoric acid (HPW) catalysts supported on mesoporous molecular sieves SBA-15 were prepared by a one-pot hydrothermal method and their physical and chemical properties were characterized by various techniques such as fourier transform infrared spectroscopy, powder X-ray diffraction, nitrogen adsorption–desorption and transmission electron microscopy. It has been found that all the catalysts retained the mesopore structure of SBA-15 and the primary Keggin-type structure of heteropoly acid. The surface areas and pore volumes of HPW-SBA-15 decreased with the increase of HPW heteropoly acid loadings. HPW units were mostly encapsulated inside the mesopores of SBA-15. The prepared catalysts showed excellent multifunctional catalytic properties. Their bifunctional catalytic performances were examined by photo-catalytic degradation of rhodamine-B dye and microwave-catalytic synthesis of isoamyl acetate. The sample with 20 wt% loading of 12-tungstophosphoric acid was found to be more active than the other catalysts under the photo and microwave-catalytic reaction conditions. Accordingly, reasons for the catalytic activity difference were simply explicated by the effect of HPW concentration on the physicochemical characteristic of HPW-SBA-15 catalysts such as surface areas, porosity, and mesostructure.     

Catalytic combustion of benzene over metal oxides supported on SBA-15

The catalytic combustion of benzene over metal oxides supported on SBA-15 was investigated. The catalysts were prepared by the incipient wetness method and characterized by XRD, BET, TEM, ESR and TPR. The calcined siliceous SBA-15 and CuO/SBA-15 samples displayed well-resolved patterns with a sharp peak at about 1.0°. It is clear that the loading of CuO on the silica matrix drastically decreases the surface area and pore volume of the catalysts, as would be expected for the incorporation of CuO. Among the supported metal oxides, CuO supported on SBA-15 was found to have the highest activity for benzene oxidation. In addition, copper oxide supported on SBA-15 gives higher catalytic activity than copper oxide supported on MCM-41. From the ESR results, the CuO dispersed on the SBA-15 acts as the active site of the CuO/SBA-15 catalysts in the oxidative decomposition of benzene. The catalytic activity gradually increases with increasing CuO loading on SBA-15.     

SBA-15分子筛负载磷钨酸催化合成己二酸

采用SBA-15分子筛等体积浸渍负载磷钨杂多酸制备了PW/SBA-15催化剂,应用XRD、DSG-TGA等对催化剂结构进行分析和表征。结果表明,SBA-15分子筛在负载磷钨酸后,磷钨杂多酸完全引入到SBA-15分子筛的骨架结构中,其稳定性大幅增加。同时采用"一锅煮"的方法用过氧化氢氧化环己烯制得己二酸,运用正交试验法和单因素实验法对催化剂性能进行评价。结果表明,催化剂用量1.75 g、反应时间9 h、反应温度80℃、n(H_2O_2)∶n(环己烯)=5.47∶1,反应开始加入13.75 mL的H_2O_2,4 h后再加入13.75 mL的H_2O_2条件下合成的己二酸收率和纯度最高。     

PW/MCM-41催化剂的合成及对合成柠檬酸三丁酯反应的研究

制备了负载H₃PW₁₂O₄₀(PW)杂多酸的PW/MCM-41催化剂,用XRD和BET等方法表征了催化剂的结构。在负载质量分数达40%的催化剂上,XRD未检测到PW杂多酸的晶相峰。考察了不同负载质量分数的 PW/MCM-41催化剂对反应的影响。重点讨论了催化剂的活化温度、酸醇摩尔比和反应温度等因素对酯化反应的影响。最佳操作条件：PW/MCM-41负载杂多酸催化剂的磷钨酸最佳负载质量分数 40%,催化剂焙烧温度300 ℃,酸醇摩尔比1∶4,反应温度140 ℃,反应时间6～7 h。实验结果表明,负载质量分数为40%的PW/MCM-41催化剂是替代硫酸合成柠檬酸三丁酯的理想催化剂,且稳定性良好。     

负载型杂多酸的制备及其光催化性能研究

采用溶胶-凝胶法制备了负载型杂多酸H3PW12O40/SiO2、H4SiW12O40/SiO2、H3PMo12O40/SiO2催化剂,利用X射线衍射（XRD）对其结构进行了表征;考察了负载型催化剂对甲基橙溶液的光催化降解,探究了催化剂的循环使用次数。结果表明,负载型杂多酸是一种非晶态复合物;H3PW12O40/SiO2对甲基橙溶液的降解有最高的活性,其经回收循环利用,第4次脱色率仍能达到60%左右。     

Bifunctional Materials for the Catalytic Conversion of Cellulose into Soluble Renewable Biorefinery Feedstocks

The combination of Br?nsted acidity with metallic functionality in a mesoporous catalyst offers a potential pathway for the conversion of cellulose into sugar alcohols that may be used as a sustainable source of renewable biorefinery feedstock. Supported Ru catalysts were prepared by evaporative deposition on various ordered mesoporous silicas (SBA-15) with different functionalities and characterized using multiple experimental techniques. The catalytic performance of the supported Ru catalysts was compared to that of the corresponding supports and of Ru/C. We studied the effects of functional group loading, reaction time and temperature on the activity and products yield of the bifunctional catalysts by monitoring the cellulose conversion and the production of sugars and sugar alcohols in a high-pressure batch reactor. Sorbitol is the main product obtained by the hydrolysis of cellulose to glucose followed by the corresponding reduction. Secondary products include sugars, ethylene glycol and glycerol. The activity of mesoporous silica catalysts increases with an increase in acid loading and the addition of Ru allows control of the selectivity towards sugar alcohols. Ruthenium supported on arenesulfonic acid-functionalized mesoporous silica (Ru/SBA-15S) displays the best catalytic performance. Ru/SBA-15S is more hydrothermally stable than SBA-15, but loses a significant fraction of its surface area, crystallinity, acidity and activity after prolonged exposure to water at 483?K.