Gas Phase Selective Catalytic Oxidation of Toluene to Benzaldehyde on V_2O_5-Ag2O/η-Al_2O_3 Catalyst

Gas phase selective catalytic oxidation of toluene to benzatdehyde was studied on V_2O_5-Ag_2O/η-Al_2O_3 catalyst prepared by impregnation. The catalyst was characterized by XRD, XPS, TEM, and FT-IR. The catalytic results showed that toluene conversion and selectivity for benzaldehyde on catalyst sample No.4 (V/(V+Ag)=0.68) was higher than other catalysts with different V/Ag ratios. This was attributed to the higher surface area, larger pore volume and pore diameter of the catalyst sample No. 4 than the other catalysts. The XRD patterns recorded from the catalyst before and after the oxidation reaction revealed that the new phases were developed, and this suggested that silver had entered the vanadium lattice. XPS results showed that the vanadium on the surface of No.4 and No.5 sample was more than that in the bulk, thus forming a vanadium rich layer on the surface. It was noted that when the catalyst was doped by potassium promoter, the toluene conversion and selectivity for benzaldehyde were higher than those on the undoped catalyst. This was attributed to the disordered structure of V_2O_5 lattice of the K-doped catalyst and a better interracial contact between the particles.

Selective Oxidation of Toluene with Hydrogen Peroxide Catalyzed by V-Mo-based Catalyst

The selective catalytic oxidation of toluene with hydrogen peroxide over V-Mo-based catalysts under mild conditions was studied.The promotion effect of Mo on the catalysts was studied with V/Al2O3 and Mo/Al2O3 as reference samples.The catalysts were characterized by XRD,TPR,and XPS techniques.The results show that the addition of Mo to V/Al2O3 may change the distribution of V species on Al2O3 surface.Over V-Mo/Al2O3 catalyst,highly dispersed amorphous V species facilitates benzaldehyde formation,and crystalline V2O5 species increases the conversion of toluene but decreases the selectivity to benzaldehyde,while AlVMoO7 species favors both the conversion of toluene and the formation of cresols.The yield of benzaldehyde depends remarkably on the surface O/Al and Mo/V atomic ratios,and gets to a maximum value of 13.2% with a selectivity of 79.5% at an O/Al atomic ratio of 3.0 and Mo/V atomic ratio of 0.7.

Adsorption of toluene, ethylbenzene and xylene isomers on multi-walled carbon nanotubes oxidized by different concentration of NaOCI

Multi-walled carbon nanotubes （MWCNTs） were fabricated and oxidized by different concentrations of sodium hypochlorite （NaOC1） solutions. The untreated MWCNTs and modified MWCNTs were employed as adsorbents to study their characterizations and adsorption performance of toluene, ethylbenzene and xylene isomers （TEX） in an aqueous solution. The physicochemical properties of MWCNTs were greatly affected after oxidation, which influences TEX adsorption capacity. The 3% NaOCl-oxidized MWCNTs shows the greatest enhancement in TEX adsorption, followed by the 30% NaOCl. More interestingly, the 15% NaOCl-oxidized MWCNTs has lower adsorption capacities than untreated MWCNTs. The adsorption mechanism of TEX on treated MWCNTs is attributed to the combined action of hydrophobic interaction, π-π bonding interaction between the aromatic ring of TEX and the oxygen-containing functional groups of MWCNTs and electrostatic interac- tion. 3% NaOCl solution could not only introduce much oxygen-containing functional groups on MWCNTs, but also lead to less damage for the pore structure. This suggests that the CNTs-3% NaOCl is efficient adsorbent for TEX and that they may possess good potential for TEX removal in wastewater treatment.

One-Pot Synthesis of Bismuth Basic Nitrate-Bi_(2)MoO_(6) Photocatalyst for Selective Oxidation of Toluene

The key issues to improve the performance of photocatalysts for selective oxidation of toluene are promoting the migration and separation of charge carrier,and enhancing the generation of active oxygen species.It is known that the construction of compact heterojunction is an efficient protocol to inhibit photogenerated electron-hole recombination.In this work,a 2D-2D[Bi_(6)O_(6)(OH)_(3)](NO_(3))3·1.5H2O-Bi_(2)MoO_(6)(denoted as BBN-BMO)composite heterojunction has been prepared by one-step hydrothermal method for the first time.The tetragonal phase BBN in the composite plays the role of transferring electrons from the visible light activated orthorhombic phase BMO and promoting the generation of active·O_(2)^(-),the holes left in BMO are used to activate toluene and produce benzyl radical,thus greatly improving the photocatalytic performance for selective oxidation of toluene.The toluene conversion rate of BBN-BMO is 3466μmol·g^(-1)·h^(-1),which is three times that of pure BMO.The selectivity to benzalde-hyde is 94.2%.In addition,reasonable mechanism has been speculated based on a series of control experiments.

无溶剂下钴卟啉/NHPI催化甲苯选择性氧化制备苯甲醛

以钴卟啉/N-羟基邻苯二甲酰亚胺(NHPI)为催化剂,分子氧为氧化剂,在无溶剂的条件下,研究温和条件下催化甲苯选择性氧化制备苯甲醛的工艺。在甲苯0.2 mol、钴卟啉物质的量分数1×10^(-4)%、NHPI物质的量分数0.25%、70℃、O_(2)压力2.0 MPa和3 h优化条件下,甲苯转化率为5.5%,苯甲醛、苯甲醇和苯甲酸选择性分别为88.0%、10.2%和0.8%。通过原位红外和电子顺磁共振波谱仪等表征方法,表明该反应机理为典型的自由基反应过程。

Influence of doping nitrogen on the catalytic performance of carbon nanotubes encapsulating cobalt for selective oxidation of arylalkanes

Efficient selective oxidation of hydrocarbons to corresponding ketones has been a significant but challenging work in the past decades.Here,a nitrogen-doped bamboo-like carbon nanotubes encapsulating cobalt catalyst(NCNTs-X)using citric acid,melamine and CoCl_(2)·6H_(2)O as precursors was synthesized by a simple pyrolysis method.A series of characterization techniques were employed to investigate the physicochemical properties of samples.And the results show that the as-prepared catalysts achieve a high catalytic performance for selective ethylbenzene oxidation(78.3% ethylbenzene conversion)using molecular oxygen as oxidant,especially giving a high selectivity(93.8% selectivity to acetophenone).According to the investigation of the structure-activity relationship of the catalysts,it can be deduced that the Co-N_(x) sites have an obvious positive effect on catalytic performance thanks to the synergistic effect between metallic cobalt and pyridinic N.

V-Sn氧化物催化甲苯气相氧化制苯甲醛

采用溶液混合法和浸渍法制备了一系列 V2 O5- Sn O2 二元氧化物和 V2 O5- Sn O2 / η- Al2 O3 负载型催化剂 .V2 O5与 Sn O2 构成的二元氧化物样品与单氧化物及其 V2 O5- Sn O2 / η- Al2 O3 的性质不同 .负载型催化剂的活性明显高于二元氧化物样品的活性 ,甲苯转化率和苯甲醛选择性与催化剂的组成有较好的对应关系 .随着 Sn O2 的引入 ,催化剂活性缓慢降低 ,苯甲醛的选择性逐渐减小 ,可见 Sn O2 不适合作为甲苯氧化反应的催化剂组分 .X射线衍射实验结果表明 ,Sn O2 的作用主要是为钒的分散提供骨架 .

钒基催化剂在双氧水存在下对甲、乙苯液相选择氧化的研究

研究了若干钒基催化剂在双氧水存在下对甲、乙苯的液相选择性氧化催化性能 .结果表明 :在乙腈为溶剂的反应体系中 ,所研究的钒基催化剂包括VPO ,VOPO4,V2 O5,VO(acac) 2 和NH4VO3 等均表现出以苯甲醛为甲苯选择性氧化主产物和以苯乙酮为乙苯选择氧化主产物的反应结果 ;从反应活性和主产物选择性来看 ,按以下顺序递减 :VPO >V2 O5>VOPO4>VO(acac) 2 >NH4VO3 .对于具有 (VO) 2 P2 O7晶相的VPO催化剂 ,在双氧水存在下对甲苯选择性氧化主产物苯甲醛的最高选择性为 5 8 8% ,乙苯选择性氧化主产物苯乙酮的最高选择性为 67 8% ;其催化性能与P/V比、焙烧条件、双氧水的使用量、反应溶剂等有关 .从已有的实验结果推测 ,钒基催化剂在双氧水存在下的甲、乙苯选择氧化反应与V5+ /V4+ 的“氧化 -还原”作用密切相关 .

苯甲醛清洁生产工艺技术研究进展

介绍了苯甲醛清洁生产工艺的甲苯气相氧化、甲苯液相氧化、苯甲醇氧化、苯甲酸还原法、苯甲酸甲酯还原法、间接电解氧化法及其氧化反应动力学、甲苯三氧化二锰非均相氧化、甲苯超(近)临界流体法、近临界水法等; 提出三氧化二锰非均相氧化法和近临界水法具有比较好的工业应用前景。

CO_2选择性氧化乙苯制苯乙烯

本文评述了近年来国内外利用温室气体CO2 选择性氧化乙苯制苯乙烯的研究进展。和乙苯直接脱氢法相比 ,新工艺不仅能降低反应温度 ,大幅度降低能耗 ,还能在一定程度上抑制催化剂的失活。氧化铝负载的Fe系催化剂和活性炭负载的La等过渡金属改性的V系催化剂具有较好的催化活性。CO2 对乙苯脱氢的显著促进作用要归因于金属氧化物催化剂的氧化还原机制以及乙苯脱氢和逆水煤气变换反应耦合的协同作用。尽管新工艺显示了良好的应用前景 ,但在将来的研究工作中还要强化催化剂失活机理的研究 ,开发新型高效催化剂并对新工艺的成本进行详细的评估。

微波条件下V_2O_5/TiO_2低温选择氧化甲苯制苯甲酸

在微波辐射条件下，考察了甲苯选择氧化过程中催化剂床层温度、Ｏ２／甲苯比、原料气总空速、Ｖ２Ｏ５担载量和添加氧化物助剂等条件对Ｖ２Ｏ５／ＴｉＯ２催化剂活性的影响．结果表明，在微波作用下，当床层温度在２５０℃，Ｏ２／甲苯摩尔比６和原料气总空速１００００ｈ－１时，１％ＭｏＯ３－８％Ｖ２Ｏ５／ＴｉＯ２上的苯甲酸和苯甲醛的收率分别达到４１％和１４％．与传统加热的催化过程相比，苯甲酸和含氧化物的收率均有较大的提高．还初步探讨了微波对催化剂活性的影响．

碱金属改性Y分子筛的甲苯氧化甲基化反应性能及其酸碱性质

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镧-钼复合氧化物超细微粒催化剂结构和甲苯选择氧化催化性能

镧－钼复合氧化物超细微粒催化剂结构和甲苯选择氧化催化性能匡文兴范以宁陈开东邱金恒王镇浦＊陈懿（南京大学化学系，南京２１００９３；＊南京化工大学应化系，南京２１０００９）关键词：镧－钼复合氧化物超细微粒结构甲苯选择氧化近年来，有关甲苯选择氧化方面的文献...

甲苯液相选择氧化反应催化剂研究进展

以过渡金属氧化物及其负载型催化剂、杂多酸及其负载型催化剂、过渡金属络合物及其负载型催化剂、沸石分子筛基催化剂、超临界CO2介质催化反应体系为线索,评述了各类甲苯液相选择氧化反应催化剂的特性和近年来的研究进展,展望了甲苯液相选择氧化反应催化剂的发展方向,提出以反应对催化剂的结构和性质为指导来研制高效、"绿色"的催化剂仍是甲苯液相选择氧化反应的关键。

镧钼钒磷杂多配合物催化乙苯选择性氧化制苯乙酮

The lanthanum molybdovanadophosphoric tetrabasic heteropoly complex was synthesized.Catalytic properties of the title heteropoly complex for selective oxidation of ethylbezene to acetonphenone was investigated.The suitable reaction conditions was discussed.

铈钼氧化物表面氧性质和催化性能

A series of Ce-Mo oxide catalysts with different Ce/Mo atomic ratio were prepared and applied to selective oxidation of toluene to benzaldehyde. The structures and properties of the surfaces of catalysts were characterized by XRD, TPR and DR-UVS. The natures of oxygen species on the surfaces of these samples were studied by using temperature programmed desorption-mass spectrography(TPD-MS). The results showed that the oxygen species of multiple adsorption existed on the sample surface. And in the range of desorption temperature<900℃, for the Ce-Mo samples, not only the desorption peaks of O- species on surfaces of samples be discoved, but also the O2- species appeared. As the content of Ce in Ce-Mo oxides was changed, the activation energy of oxygen desorption(Ed) also changed. The Ed value of sample 3 (Ce/Mo=1/1) is the lowest and its selectivity of benzaldehyde in toluene oxidation is the highest. Thus, a Parallel relation between the Ed value and the selectivity for benzaldehyde existed in these Ce-Mo oxides.

铈钼氧化物对甲苯气相选择氧化制苯甲醛的催化性能

研究了一系列铈钼复合氧化物对甲苯选择性氧化制苯甲醛反应的催化性能．结果表明，当Ｃｅ／Ｍｏ比为２／１，温度为４５０℃，空气／甲苯比为１０时，反应活性最好．采用ＸＲＤ，ＩＲ，ＸＰＳ和Ｈ２ＴＰＲ等技术对该样品的组成、结构、表面状态以及氧化还原性质进行了表征．

As-V-O簇合物对乙苯选择氧化反应的催化活性

通过水热方法合成了簇合物［Ｎ（ＣＨ３）４］４［Ａｓ８Ｖ１４Ｏ４２（８Ｈ２Ｏ）］及其相近的同多及杂多钒氧簇Ｋ６Ｖ１０Ｏ２８·９Ｈ２Ｏ，ＮａＫＶ２Ｏ６，（Ｈ２Ｅｎ）０．５Ｖ２Ｏ５，（Ｈ２Ｅｎ）３（ＶＯ）９（ＰＯ４）８，Ｎａ３ＶＯ（ＨＰＯ４）（ＰＯ４）·Ｈ２Ｏ．运用ＸＲＤ和ＩＲ等手段表征了［Ｎ（ＣＨ３）４］４［Ａｓ８Ｖ１４Ｏ４２（８Ｈ２Ｏ）］的结构．该类化合物对于催化乙苯过氧化氢选择氧化制苯乙酮具有较高的催化活性．通过比较含钒与不含钒化合物的活性情况，讨论了催化氧化的活性中心．

负载钴催化剂的合成及其催化环己烷和甲苯选择氧化的研究

采用溶胶 凝胶法制备了系列负载型钴催化剂 ,并将其用于催化环己烷和甲苯选择氧化制备环己醇、环己酮和苯甲酸的反应 .考察了不同钴含量、催化剂焙烧温度、反应温度、反应时间和压力对催化剂活性的影响 .结果表明 ,在 3%Co/Al(OH) x 15 0上环己烷的转化率为 15 1% ,环己醇和环己酮的选择性为 91 2 % ;在V(乙酸 ) ∶V(甲苯 ) =1∶8的条件下 ,在 1%Co/Al(OH) x 15 0上甲苯的转化率为 4 8 9% ,苯甲酸的选择性为 96 1% .采用AES ,BET ,XRD及XPS等技术对催化剂进行了表征 .