活性炭载体对甲醇氧化羰化合成碳酸二甲酯催化活性的影响

:采用气相直接法甲醇氧化羰化工艺路线合成碳酸二甲酯 ,以 Cu Cl2 为活性组分 ,用浸渍法制备催化剂。关联了两种煤质活性炭作为载体时孔结构与活性的关系 ,并考察了不同表面处理或表面改性方法对催化活性的影响。     

十聚钨酸盐选择性催化H_2O_2氧化苯甲醇合成苯甲醛

合成了6种十聚钨酸盐化合物,考察了它们在无溶剂、无卤素、无相转移催化剂条件下用30%H2O2氧化苯甲醇合成苯甲醛反应中的催化活性。结果表明,该体系是一种高效的环境友好催化体系。6种十聚钨酸盐在反应过程中显示了较高的活性,其中以十聚钨酸十六烷基吡啶盐的催化活性最好,在温度90℃下,反应1.5 h,苯甲醛的收率和选择性分别达到93.5%和98%。时间、H2O2加入量、温度、催化剂加入量等条件对催化剂活性有明显的影响,适宜的反应条件为:n(苯甲醇)∶n(催化剂)∶n(H2O2)=10∶0.05∶11,反应温度为90℃,反应时间为1.5 h。     

无溶剂法OMS-2催化氧化苯甲醇制苯甲醛的研究

以高锰酸钾和富马酸为原料,采用超声波辅助溶胶-凝胶法快速合成氧化锰八面体分子筛（OMS-2）,并考察了不同锰氧化物在无溶剂、无卤素条件下用70%过氧化氢叔丁醇（TBHP）氧化苯甲醇合成苯甲醛反应中的催化活性。结果表明,该体系是一种高效的环境友好催化体系,OMS-2在反应过程中显示了较高的活性,在80 ℃下,反应4 h,苯甲醇转化率、苯甲醛收率和选择性分别为44.72%、34.31%和76.74%。对该催化体系的重复使用性能进行了考察,结果发现,催化剂重复使用3次之后,苯甲醛收率和选择性稍微降低,表明OMS-2催化剂循环使用活性较好。     

硼杂碳包镍负载钯催化芳香醇需氧氧化

以硼杂碳包镍(Ni@BC)为载体,采用乙醇还原前驱体H_2PdCl_4法制备了一种新型磁可分离Pd/Ni@BC催化剂,并对其进行AAS、TEM、XRD和XPS表征,选取苯甲醇需氧氧化为探针反应,考察催化剂用量、反应温度和反应时间对催化性能的影响,研究催化剂对其他芳香醇的催化性能和循环使用性能。AAS结果表明,Pd负载质量分数为9.1%,与理论负载量一致。TEM结果显示,Pd纳米颗粒均匀分散在载体表面,平均粒径为4 nm。XRD和XPS结果均表明,催化剂的活性物种为Pd0。在反应温度80℃、O2_压力101.325 k Pa(流速20 m L·min~(-1))、CH_3CN为溶剂和K_2CO_3为碱性助剂条件下,Pd/Ni@BC对多种芳香醇的氧化反应表现出很高的催化活性和选择性,能将苯甲醇、对甲基苯甲醇、对乙基苯甲醇、对异丙基苯甲醇、肉桂醇、安息香、二苯甲醇以及邻甲基苯甲醇等定量转化为相应的醛或酮。催化剂重复使用5次,苯甲醇转化率由97.3%降至78.9%,Pd的少量脱落和部分氧化是催化剂活性降低的主要原因。     

铜、铁双金属离子交换的Y型沸石的催化性能研究

采用离子交换法制备了系列含双金属离子的Cu-Fe/Y催化剂，考察了该催化剂在环己烷氧化、H₂O₂分解及苯甲醇氧化中的催化性能。结果表明,当n(Cu)∶n(Fe)=2.06时，Cu-Fe/Y在环己烷氧化反应中其催化活性高于相对应的Cu/Y和Fe/Y催化剂，表现出协同效应。Cu-Fe/Y在苯甲醇氧化中的催化活性均低于相应的Cu/Y和Fe/Y催化剂。在H₂O₂分解反应中，Cu-Fe/Y的反应活性近似等于两种金属离子催化活性的加合。在H₂O₂分解反应中，Cu-Fe/Y的反应活性近似等于两种金属离子催化活性的加合。Cu-Fe/Y在苯甲醇氧化中的催化活性均低于相应的Cu/Y和Fe/Y催化剂。     

载体及镍源对镍催化剂催化苯酐选择性加氢反应的影响

分别以SiO2、TiO2、TiO2-SiO2、TiO2-Al2O3和TiO2-ZrO2为载体,以硝酸镍为镍源,采用浸溃法制备出一系列镍基催化剂,考察了不同载体对镍催化剂催化苯酐选择性加氢合成苯酞性能的影响;并考察了以TiO2-ZrO2为载体,分别以硝酸镍、乙酸镍和柠檬酸镍为镍源制备的镍催化剂的加氢性能.通过BET、XRD、SEM等方法对催化剂进行了表征.结果表明,载体对镍催化剂上苯酐加氢反应的影响较大,其中复合氧化物TiO2-SiO2和TiO2-ZrO2负载的镍催化剂上Niu活性组分晶粒度较小,分散度较高,催化剂表现出很好的催化活性和苯酞选择性.此外,以不同镍源制备的Ni/TiO2-ZrO2催化剂性能差异较明显,由乙酸镍制备的催化剂上Niu物种粒度较大,活性较低,由硝酸镍和柠檬酸镍制备的催化剂表现出很高的催化活性和选择性,其中由柠檬酸镍制备的催化剂性能略高于硝酸镍,在实验反应条件下,苯酐转化率为97.1%,苯酞收率为92.9%.     

SiO_2负载磷钨酸催化氧化合成苯甲醛的研究

本文通过以30%双氧水为氧化剂,以介孔SiO2负载磷钨酸为催化剂,对苯甲醇氧化合成反应进行了研究,讨论了各因素对反应的影响。结果表明:85℃下催化H2O2氧化苯甲醇,3.5 h可使100mol苯甲醇氧化,其转化率达到92.4%,同时介孔SiO2负载磷钨酸作为催化剂有较好的催化活性,而且可以重复使用。     

二氧化硅负载磷钨酸催化氧化环己醇为环己酮的研究

以二氧化硅为载体,采用等体积浸渍法制备了负载磷钨酸催化剂,利用XRD和FT-IR对催化剂进行了表征,并以H2O2(30%)为氧化剂,初步评价了催化剂催化氧化环己醇为环己酮的催化性能。结果表明,负载催化剂保持了磷钨酸的Keggin结构,在催化氧化环己醇的反应中表现出较强的催化活性,产物中只有环己酮;反应温度、时间等反应条件对催化氧化反应有明显的影响,在最佳条件下,环己醇转化率为86.5%;该氧化体系具有较宽的应用范围,实验所用伯醇、仲醇较好的氧化转化为相应的醛或酮。     

微波制备CuCl_2/SiO_2-TiO_2催化剂的结构及其催化性能

采用浸渍法将CuCl_2分散到SiO_2-TiO_2载体表面,微波炉处理一定时间得到催化剂样品,考察了样品在甲醇氧化羰基化反应中的催化活性。结果表明,样品中负载CuCl_2物质的量分数为15%时,活性最佳,甲醇转化率和碳酸二甲酯选择性分别为8.25%和85.01%。微波辐射导致CuCl_2高度分散于SiO_2-TiO_2上,并与载体表面发生键合作用,降低了催化剂中对设备具有腐蚀作用的Cl含量,同时形成结构稳定的活性铜物种。     

CeO2基氧化物在氧化羰基化合成碳酸二苯酯中的应用

用溶胶一凝胶法制备了系列CeO2基复合金属氧化物载体,用沉淀法负载活性组分Pd得到0．5％Pd固相催化剂,采用XRD、SEM、BET等手段对载体进行了表征。以非均相催化苯酚一步合成碳酸二苯酯的反应为考察对象,对催化活性进行了评价。结果表明,CeO2经金属元素掺杂后其催化活性可得到明显的提升,其中经锰掺杂催化活性最好,DPC收率可达9．33％。     

Enhancing the catalytic activity of carbon nanotubes by nitrogen doping in the selective liquid phase oxidation of benzyl alcohol

Nitrogen-doped carbon nanotubes (N-CNTs) were prepared by chemical vapor deposition method and employed as carbon-based catalysts for selective oxidation of benzyl alcohol to benzaldehyde with molecular oxygen as the terminal oxidant under the mild reaction conditions. The results showed that the N-CNTs exhibited much higher activity than the undoped CNTs, and the improved catalytic activity was probably attributed to the introduction of electron-rich nitrogen atoms in the graphitic domains enhanced electron transfer. Moreover, N-CNTs displayed excellent stability without an obvious loss in activity and selectivity for benzyl alcohol oxidation after eight cycling reactions. The results presented herein pave the way for the development of novel carbon catalyst for the liquid-phase oxidation of benzyl alcohol.     

掺杂Co对CNTs负载Pt催化剂上肉桂醛选择性催化加氢性能的影响

研究了Co的掺杂对Pt/CNTs催化剂催化加氢肉桂醛反应性能的影响。结果发现, Co的掺杂对Pt/CNTs催化剂催化加氢活性起到明显促进作用, 并有利于C＝O基团的选择性加氢。Pt-0.17% Co/CNTs催化剂显示了较高的肉桂醇加氢选择性, 在反应条件为70℃、2 MPa和1.5 h时, 肉桂醛的加氢转化率达到97.1％,生成肉桂醇的选择性达到93.6％。同时, 初步研究了该催化剂上肉桂醛催化加氢反应动力学, 催化反应的活化能为26.5 kJ•mol^-1。     

过渡金属氧化物修饰的金纳米催化剂苯甲醇氧化性能

采用一步法合成介孔二氧化硅负载的金纳米催化剂,以氯化锡为前驱体,通过浸渍法向金纳米催化剂中引入助剂氧化锡,得到过渡金属氧化物修饰的金纳米催化剂。通过N2吸附-脱附、X射线衍射、透射电镜和固体紫外漫反射光谱等对催化剂结构进行表征。将所合成的催化剂用于苯甲醇选择性氧化反应,考察助剂组分对催化剂性能的影响,结果表明,氧化锡的引入改变了金纳米颗粒的表面电子结构,增加了催化剂活性与选择性;但随着氧化锡含量继续增加,催化剂活性降低,这主要是因为金纳米颗粒表面过渡金属氧化物覆盖度增加,减少了催化剂活性组分与苯甲醇的接触。当氧化锡质量分数0.2%时,催化剂效果最佳,在100℃和氧气压力0.2 MPa下反应3 h,苯甲醇转化率25.7%,苯甲醛选择性75.9%,苯甲酸选择性15.8%,苯甲酸苄酯选择性6.3%。     

碳纳米管负载纳米二氧化钌一步催化氧化环己烷

以不同载体负载的纳米二氧化钌作为催化剂，O₂为氧化剂，实现一步催化氧化环己烷制备己二酸，考察催化剂载体、引发剂、反应时间、温度和压力对环己烷转化率和己二酸选择性的影响。结果表明，碳纳米管负载纳米二氧化钌作为催化剂具有高的活性和选择性；在125 ℃、1.5 MPa和反应6 h的条件下，环己烷转化率达到40％，己二酸选择性达80％以上；催化剂可重复使用，具有较好的稳定性。     

Fischer–Tropsch synthesis over cobalt dispersed on carbon nanotubes-based supports and activated carbon

Carbon nanotubes (CNTs) and the ones grown on MgO and alumina are used as supports for cobalt catalyst in Fischer–Tropsch (FT) synthesis. Carbon nanotubes were synthesized by chemical vapor deposition of methane on 5.0 wt.% iron on MgO or alumina at 950 °C. The carbon nanotubes were characterized by SEM and TEM microscopy and Raman spectroscopy. Cobalt nitrate was impregnated onto the supports by impregnation, and the samples were dried and reduced in-situ at 400 °C for 12 h, and then FT synthesis was carried out in a fixed-bed reactor. The catalysts were characterized by BET surface area measurement, TPR and TPD. The effect of carbon nanotubes as cobalt support on CO conversion, product selectivity, and olefin to paraffin ratio of FT synthesis was investigated and compared with activated carbon as well as Al₂O₃, as a traditional support. The results revealed that the activity of the Co/CNT catalyst was improved by 22%, compared to the conventional Co/alumina catalysts. Also the cobalt supported on CNTs grown on MgO (Co/CNT–MgO) shows the highest selectivity to C₅₊ as the most desired FTS products. The C₅₊ selectivity enhancement was about 37, 34, 17, and 77% as compared to the Co/CNT, Co/alumina, Co/CNTs-alumina, and Co/activated carbon, respectively. Also the olefin/paraffin ratio on the Co/CNTs-MgO catalyst is about 7.7 times higher than the conventional cobalt catalysts. It seems that the degree of reduction of cobalt is higher when supported on CNTs than on alumina. This leads to higher FTS activity. Also, the particle size distribution of the cobalt is affected by the CNT–MgO support leading to higher C₅₊ selectivity.     

有机锡催化合成乙酸苄酯新工艺研究

以新型不同类型的有机锡化合物为催化剂,对乙酸苄酯的酯化反应进行了研究,重点考察了不同类型的有机锡催化剂的催化效果、催化剂用量、反应温度、反应时间、酸醇摩尔比和带水剂等因素对乙酸苄酯产率的影响。实验结果表明,Ph3SnCl对合成乙酸苄酯有着良好的催化活性,当催化剂用量为苯甲醇和乙酸总质量1．5％,乙酸和苯甲醇的摩尔比为2．5：1,甲苯为10mU与苯甲醇的摩尔比为0．60）,温度110℃,反应150min后,乙酸苄酯产率可达98．4％．且催化剂重复使用5次仍保持较高活性。     

An Efficient and Recyclable Catalyst for N‐Alkylation of Amines and β‐Alkylation of Secondary Alcohols with Primary Alcohols: SBA‐15 Supported N‐Heterocyclic Carbene Iridium Complex

A mesoporous silica (SBA‐15)‐supported pyrimidine‐substituted N‐heterocyclic carbene iridium complex was prepared and used as a catalyst for both environmentally friendly N‐alkylation of amines and β‐alkylation of secondary alcohols with primary alcohols. The structure of the supported iridium catalyst was characterized by Fourier transform infrared (FT‐IR), ¹³C and ²⁹Si solid‐state nuclear magnetic resonance (NMR), small‐angle X‐ray scattering (SAXS), transmission electron microscopy (TEM), iridium K‐edge X‐ray absorption near‐edge structure (XANES) and extended X‐ray absorption fine structure (EXAFS) spectroscopic analyses which demonstrated that the coordination environment of the iridium centre and the 3‐dimensional‐hexagonal pore structure of SBA‐15 were retained after the immobilization. The catalyst was found to be highly efficient for both kinds of reaction on a wide range of substrates under mild conditions. Moreover, the supported iridium catalyst was obviously superior to the unsupported one in the N‐alkylation of aniline and β‐alkylation of 1‐phenylethanol with benzyl alcohol as substrate, which indicated that not only the iridium complex moiety but also the support material contributed to the catalytic activity of the supported iridium catalyst in these reactions. The supported iridium catalyst can be easily recycled by simple washing without chemical treatment, and exhibited excellent recycling performance without notable decrease in catalytic efficiency even after twelve test cycles for N‐alkylation of aniline with benzyl alcohol, nine cycles for N‐alkylation of different amines with different alcohols, and eight cycles for β‐alkylation of 1‐phenylethanol with benzyl alcohol, respectively.     

Enhancement of MoO3–K2O/CNTs nanocatalyst activity and selectivity in higher alcohols synthesis using microemulsion technique

Alkalized MoS₂ nanocatalysts supported on carbon nanotubes (CNTs) is prepared using microemultion technique with water-to-surfactant ratios of 1–4. The nanocatalysts were extensively characterized by different methods and their activity and selectivity in higher alcohols synthesis (HAS) been assessed in a fixed bed micro-reactor. The physico-chemical properties and performance of the nanocatalysts were compared with the catalyst prepared by impregnation method. Very narrow particle size distribution has been produced by the microemulsion technique at the relatively high loading of active metal (15 wt.% Mo). The TEM images showed that small Mo nanoparticles are confined inside the CNTs and the on the outer surface of the CNTs (2–7 nm). Using microemultion technique with water to surfactant ratio of one; the average MoO₃ particle sizes decreased to 4.5 nm, the %dispersion increased to 60.75 and the %reduction increased by 43%. Also, the chemical interactions between K–Mo–O species increased, enhancing the conditions for the formation of alcohols. Activity and selectivity were found to be dependent on the catalyst preparation method and water to surfactant ratio. The %CO conversion increased to 43.8%. The CNTs-supported MoO₃–K₂O nanocatalyst synthesized by the proposed microemulsion technique with water to surfactant ratio of one, decreased the hydrocarbons selectivity to 21.98% and increased the alcohols selectivity to 65.21%. Finally, using microemultion method dramatically decreased the methanol selectivity and increased ethanol and other higher alcohols selectivities.     

Selective oxidation of olefins and aromatic alcohols with tert‐butylhydroperoxide catalyzed by polymer‐anchored transition‐metal complexes

Three polymer‐anchored metal complexes (Co, Cu, and Pd) were synthesized and characterized. The catalytic performance of these complexes was tested for the oxidation of olefins and aromatic alcohols. These complexes showed excellent catalytic activity and high selectivity. These complexes selectively gave epoxides and aldehydes from olefins and alcohols, respectively. Individually, the effect of various solvents, oxidants, substrate oxidant molar ratios, temperatures, and catalyst amounts for the oxidation of cyclohexene and benzyl alcohol were studied. Under optimized reaction conditions, 96, 81, and 71% conversions of cyclohexene and 86, 79, and 73% conversions of benzyl alcohol were obtained with Co(II), Cu(II), and Pd(II) catalysts, respectively. The catalytic results reveal that these complexes could be recycled more than five times without much loss in activity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011