Highly Active Catalysts for the Hydrogenation of Styrene

Highly active catalysts composed of titanocene complexes and nanometric sodium hydride have been developed for the hydrogenation of styrene under normal pressure. The highest initial catalytic activity reached 138 s^?1 (average value in the first 1 min), which is higher than previously reported data for the hydrogenation of styrene. The highest number of catalytic turnover reached 21,700 in 2 h. An effect of steric hindrance of substituents of titanocene complexes on the catalytic efficiency was observed.     

环氧丙烷异构化制丙醛催化剂的研究

采用微反-色谱联合装置对环氧丙烷开环异构化反应中催化剂的初活性进行了评选。其中有如Al2(SO4)3/K2SO4(质量比15∶85)混合型催化剂在275℃时,环氧丙烷转化率达到97.60%,丙醛选择性达到94.57%;Al2(SO4)3/γ-Al2O3(质量比60∶40)混合型催化剂在275℃时,转化率达83.37%,选择性达到100%;硅钨酸催化剂也有比较好的催化效果,且解决了成型问题;另外还研究了反应温度以及催化剂活化方法对催化性能的影响。     

Novel Perovskite-Type Oxide Catalysts for Dehydrogenation of Ethylbenzene to Styrene

We investigated novel LaMnOx perovskite-oxide (ABO₃) catalysts for effective catalytic dehydrogenation of ethylbenzene to produce styrene monomer. Comparison with industrial Fe–K catalyst, our La_0.8Ba_0.2Mn_0.6Fe_0.4O_3-δ catalyst showed higher activity. Results show that the A-site in perovskite-type oxides affected catalytic dehydrogenation activities and that the B-site affected stability of the activities.     

Aminolysis of Styrene Oxide Over Heterogeneous Acidic Catalysts

Silica alumina and silica zirconia mixed oxides are shown to be effective and regioselective catalysts for the aminolysis of styrene oxide under very mild experimental conditions, giving the corresponding primary ??-amino-alcohol in good to excellent yield.     

异戊二烯选择性加氢非负载Ni-Mo催化剂的制备与性能

以柠檬酸为络合剂,采用溶胶-凝胶法制备了非负载Ni-Mo复合氧化物催化剂,采用N2吸附-脱附、X射线衍射(XRD)、扫描电镜(SEM)和傅立叶红外光谱(FT-IR)等手段对催化剂进行表征,以含体积分数1%异戊二烯的正辛烷溶液为模拟原料,在连续固定床上考察了Mo与Ni物质的量之比和溶剂量对催化剂二烯烃选择性加氢性能的影响。结果表明:溶胶-凝胶法制备的Ni-Mo复合氧化物催化剂具有较高比表面、分散性和双介孔结构,当Mo与Ni物质的量之比为0.6和每摩尔Ni和Mo所用溶剂量为480 mL时,Ni-Mo复合氧化物催化剂活性较高。     

选择加氢催化剂载体氧化铝的改性及其工业应用(Ⅰ)

报道了将稀土元素加入催化剂载体Al2O3中改进了Al2O3的热稳定性,调节了载体的表面酸度。用这种改性载体制成的Pd-Al2O3催化剂提高了催化剂的活性及选择性。将改性的氧化铝载体用于工业化C2选择加氢催化剂,性能卓越,降低了副产物绿油的生成量。而且改性的Al2O3作为载体,适用于制备所有石油化工加氢催化剂及环保催化剂。     

茂类金属催化剂用于苯乙烯聚合

概述了茂类金属催化剂用于苯乙烯均聚及共聚合的现状。     

正庚烷异构化催化剂研究进展

阐述了当前正庚烷异构化所用的负载型催化剂和过渡金属碳化物和氧化物催化剂的研究进展,对催化剂性能的影响因素及对策进行了分析与讨论。正庚烷异构化催化剂中,研究较多的是以SAPO、HZSM-5和Y、B型分子筛为载体的贵金属催化剂,其中SAPO分子筛载体的性能较优,Pt比Pd具有更好的催化性能,非贵金属／分子筛催化剂的活性比贵金属／分子筛催化剂相差较大。过渡金属Mo、W的碳化物和氧化物也具有较好的正庚烷异构化性能,与碳氧化物或碳化物相比,部分还原氧化物催化正庚烷异构化活性和选择性要高得多,其活性甚至高于传统的Pt/USY双功能催化剂。展望了正庚烷异构化催化剂的研究方向和意义。     

Boosting CO Hydrogenation Performance of Facile Organics Modified Iron Oxide/Reduced Graphene Oxide Catalysts

Catalysis Letters - Organics including terephthalic acid and glucose are added to selectively adsorb on iron oxide or graphene oxide, which can further modify the structure properties and...     

Bifunctional Catalysts Stabilized on Nanocrystalline Magnesium Oxide for One‐Pot Synthesis of Chiral Diols

New bifunctional catalysts composed of PdCl₄²⁻, OsO₄²⁻ and OsO₄²⁻, WO₄²⁻ designed and prepared by a counterionic stabilization technique involving the reactions of Na₂PdCl₄‐K₂OsO₄ and K₂OsO₄‐Na₂WO₄ with nanocrystalline MgO are well characterized. These bifunctional catalysts, NAP‐Mg‐PdOs and NAP‐Mg‐OsW perform tandem Heck asymmetric dihydroxylation and asymmetric dihydroxylation‐N‐oxidation reactions, respectively, in the presence of the chiral ligand 1,4‐bis(9‐o‐dihydroquinidinyl)phthalazine [(DHQD)₂PHAL] in a single pot. It is quite impressive to note that H₂O₂ is used as a terminal oxidant to provide N‐methylmorpholine N‐oxide (NMO) in situ by the oxidation of N‐methylmorpholine (NMM) in the asymmetric dihydroxylation‐N‐oxidation catalyzed by NAP‐Mg‐OsW.     

Hydrogenation and Isomerization of Methyl 9-Octadecenoates

Both methyl cis-9-octadecenoate and methyl trans-9-octadecenoate (commonly known as methyl oleate and methyl elaidate) were hydrogenated at operating conditions within the following ranges: 100–140°C, 1.7–14.6 at and 0.05–0.14% nickel catalyst. Correlations were developed for both geometrical and positional isomers as a function of iodine value. Decreases in pressure or increases in temperature resulted in a relatively greater increase in the amounts of positional isomers as compared to geometrical isomers. The rates of isomerization were found to vary between 0.7 to 2.5 times the rates of hydrogenation for hydrogenation runs with methyl cis-9-octadecenoate. The ratio between these two rates increased with higher temperatures or lower pressures. The rates of hydrogenation were compared for methyl cis-9-octadecenoate, methyl trans-9-octadecenoate, and cottonseed oil. Hydrogenation rate constants decreased in the following order: methyl trans-9-octadecenoate, methyl cis-9-octadecenoate, and cottonseed oil. The induction period that occurred only when a new catalyst was used depended on the temperature, pressure, and fatty feedstock being hydrogenated. The catalyst was activated to a considerable extent during the induction period.     

Dehydrogenation and Isomerization of n-Butane or Isobutane Over Cr Catalysts Supported on Zeolites

Dehydrogenation and isomerization of n-butane or isobutane into isobutene over Cr catalysts supported on zeolites were investigated. We found that Cr catalyst supported on H-SSZ-35-type zeolite, having one-dimensional cage-type channel structure, was very effective for this reaction and the yield of isobutene was 5.44% from n-butane and 9.57% from isobutane. In this reaction, it is suggested that dehydrogenation of butanes is accelerated by Cr₂O₃ loading, and solid acidity of the zeolite support favors isomerization.     

Dehydrocyclization of Alkanes Over Zeolite-Supported Metal Catalysts: Monofunctional or Bifunctional Route

The direct catalytic conversion of alkanes into aromatics has found potentially important industrial applications. Initially only alkanes with 6 and more carbon atoms in the chain were concerned. Supported platinum catalysts were found active for the aromatization of alkanes; the drawbacks of these catalysts were their deactivation with time on stream and the existence of simultaneous parallel reactions. Much discussion has been published on the aromatization of C₆₊ alkanes. A bifunctional mechanism which involves both the metal and the acid sites of the support and a monofunctional mechanism involving only the metallic sites operate over, respectively, Pt supported on acidic support and Pt supported on nonacidic support. In the present review the mechanisms proposed for the aromatization of alkanes are described. Over monofunctional Pt catalysts two possible mechanisms prevail: 1,6 ring closure on the Pt surface involving primary and secondary C-H bond rupture, followed by dehydrogenation of the cycloalkanes into aromatics (1,5 ring closure to a lesser extent also contributes to aromatic production); or dehydrogenation of the alkanes into olefins, dienes, and trienes followed by thermal ring closure. Zeolites were found most suitable as support for preparing catalysts more active and more selective in the alkane aromatization. In addition catalysts based on noble metals supported on zeolite appeared more resistant against deactivation by coke. In this review the aromatization of hexane, heptane, and octane over Pt-zeolite catalysts is discussed in detail. Comparisons between different zeolite structures and different dehydrogenation sites are given. In particular a critical analysis of the results and interpretation concerning Pt-KL catalysts strongly suggests that the exceptional high selectivity towards aromatization of n-hexane exhibited by Pt-KL could not be explained by only the nest or constraint effect exerted by the channel dimension and morphology, not by only the terminal cracking properties, not by only the partial electron transfer from the zeolite support to the Pt particles, and not by only the Pt particle size. Zeolite structure also affects the aromatic product distribution, in particular when the alkane contains more than 7 carbon atoms. It is shown how Pt on medium-pore zeolites such as In-ZSM-5, silicalites will favor the aromatization of C₈ alkane isomers into ethylbenzene-styrene with respect to other C₈ aromatics. Aromatization of light alkanes, C₂-C₅, requires the increase of the hydrocarbon chain length up to 6 carbon atoms and higher, followed by cyclization reaction. Recently new processes to convert C₂-C₅ alkanes into aromatics have been disclosed, M2-forming from Mobil, Cyclar from BP-UOP, and Aroforming from IFP-Saluted. In general these processes use bifunctional catalysts possessing a dehydrogenating and an acid function. The catalysts consist of a metal ion or metal oxide supported on a microporous acid solid. In this review we analyze the results concerning mainly platinum supported on pentasil-type zeolite. It is shown that althoug Pt has better dehydrogenating properties as compared with gallium and zinc, the efficiency of catalysts based on Pt-ZSM-5 for light alkane aromatization is less because undersirable reactions such as hydrogenolysis and ethene (olefins) hydrogenation occur on the platinum surface, resulting in the production of unreactive alkanes, CH₂, C₂H₆. These drawbacks could be partially suppressed by alloying Pt and by increasing the reaction temperature.     

Dehydrocyclization of Alkanes Over Zeolite-Supported Metal Catalysts: Monofunctional or Bifunctional Route

The direct catalytic conversion of alkanes into aromatics has found potentially important industrial applications. Initially only alkanes with 6 and more carbon atoms in the chain were concerned. Supported platinum catalysts were found active for the aromatization of alkanes; the drawbacks of these catalysts were their deactivation with time on stream and the existence of simultaneous parallel reactions. Much discussion has been published on the aromatization of C₆₊ alkanes. A bifunctional mechanism which involves both the metal and the acid sites of the support and a monofunctional mechanism involving only the metallic sites operate over, respectively, Pt supported on acidic support and Pt supported on nonacidic support. In the present review the mechanisms proposed for the aromatization of alkanes are described. Over monofunctional Pt catalysts two possible mechanisms prevail: 1,6 ring closure on the Pt surface involving primary and secondary C-H bond rupture, followed by dehydrogenation of the cycloalkanes into aromatics (1,5 ring closure to a lesser extent also contributes to aromatic production); or dehydrogenation of the alkanes into olefins, dienes, and trienes followed by thermal ring closure. Zeolites were found most suitable as support for preparing catalysts more active and more selective in the alkane aromatization. In addition catalysts based on noble metals supported on zeolite appeared more resistant against deactivation by coke. In this review the aromatization of hexane, heptane, and octane over Pt-zeolite catalysts is discussed in detail. Comparisons between different zeolite structures and different dehydrogenation sites are given. In particular a critical analysis of the results and interpretation concerning Pt-KL catalysts strongly suggests that the exceptional high selectivity towards aromatization of n-hexane exhibited by Pt-KL could not be explained by only the nest or constraint effect exerted by the channel dimension and morphology, not by only the terminal cracking properties, not by only the partial electron transfer from the zeolite support to the Pt particles, and not by only the Pt particle size. Zeolite structure also affects the aromatic product distribution, in particular when the alkane contains more than 7 carbon atoms. It is shown how Pt on medium-pore zeolites such as In-ZSM-5, silicalites will favor the aromatization of C₈ alkane isomers into ethylbenzene-styrene with respect to other C₈ aromatics. Aromatization of light alkanes, C₂-C₅, requires the increase of the hydrocarbon chain length up to 6 carbon atoms and higher, followed by cyclization reaction. Recently new processes to convert C₂-C₅ alkanes into aromatics have been disclosed, M2-forming from Mobil, Cyclar from BP-UOP, and Aroforming from IFP-Saluted. In general these processes use bifunctional catalysts possessing a dehydrogenating and an acid function. The catalysts consist of a metal ion or metal oxide supported on a microporous acid solid. In this review we analyze the results concerning mainly platinum supported on pentasil-type zeolite. It is shown that althoug Pt has better dehydrogenating properties as compared with gallium and zinc, the efficiency of catalysts based on Pt-ZSM-5 for light alkane aromatization is less because undersirable reactions such as hydrogenolysis and ethene (olefins) hydrogenation occur on the platinum surface, resulting in the production of unreactive alkanes, CH₂, C₂H₆. These drawbacks could be partially suppressed by alloying Pt and by increasing the reaction temperature.     

油脂在镍基催化剂上氢化性能的研究

研究由共沉淀方法制备的镍基催化剂上大豆色拉油加氢活性,测定氢化反应温度180℃,反应压力0．8MPa,反应时间120min,催化剂用量4％g／mL、搅拌转速360r／min条件下氢化油脂的碘值、折光指数、熔点数据,考察改变镍铝比、添加助剂铜铁镧等对催化剂在油脂氢化过程中活性的影响,镍基催化剂有较好的加氢活性。     

正丁烷异构化的研究进展

正丁烷异构化产物异丁烷是烷基化反应的主要原料和合成MTBE、ETBE等汽油添加剂的重要前躯体。从烷烃异构化反应机理、影响因素、工艺进展、催化剂研究进展等几个方面,论述了烷烃异构化催化剂的发展概况。催化剂研究新进展主要包括：贵金属改性、非贵金属改性、Mo（W）体系、硫酸锆、杂多酸等,并展望了新型催化剂的应用前景。     

介孔分子筛在长链正构烷烃异构化中的研究进展

介绍了长链正构烷烃异构化的催化剂,并着重探讨了介孔分子筛催化剂在这方面的研究进展。随着对介孔材料的不断研究,许多人从不同的合成路径和操作条件出发,合成出了多种不同组分及结构的介孔分子筛催化剂,并对有规则孔结构的介孔催化剂进行了改性,结果表明改性后的介孔催化剂对长链正构烷烃异构化具有较好的催化活性和选择性。其中一些研究成果在石油炼制和石油化学工业领域得到了广泛的应用。     

Control of the Basicity in Ni–MgO Systems: Influence in the Hydrogenation of Styrene Oxide

The addition of basic solutions to the reaction medium in the catalytic hydrogenation of styrene oxide improves the selectivity to 2-phenylethanol (used in perfumery) but also can favour condensation reactions. To study the influence of different basic sites on the reaction products, we prepared several catalysts by mixing a commercial magnesia (MgO), and other previously rehydrated (MgOr), with different amounts of NiO followed by reduction (NiMgO, 4NiMgO, NiMgOr, 4NiMgOr), and by mixing directly MgO with Ni (NiMgOa, 4NiMgOa). Ni–MgO catalysts showed the best conversion and selectivity to 2-phenylethanol values, arriving to 100% when increasing the MgO content. Interestingly, CO₂-TPD study of catalyst NiMgO indicates that metallic nickel covers the weakest basic sites of magnesia. On the other hand, CO₂-TPD profiles of Ni–MgOr and Ni–MgOa catalysts, which present low catalytic activity, showed an important amount of available basic sites that favour the formation of higher amounts of condensation products, which are responsible for the catalyst deactivation.