ESCA study of modifying effect by potassium carbonate on Pd/γ?Al2O3 catalysts

ESCA studies of the state of Pd/–Al₂O₃ catalysts modified by potassium carbonate show that such catalysts differ from unmodified samples in much greater changes of a positive charge of palladium ions under redox conversions. This is ascribed to the lower interaction of Pd with the support in modified samples.

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Pd/–Al₂O₃ . , -, Pd .

     

Physicochemical properties and hds activity of CoMo?P?Al2O3 catalysts

Porous structure, acidity and hds activity of the CoMo–P–Al₂O₃ catalysts have been studied. Phosphorus was introduced jointly with molybdenum. This method of phosphorus incorporation gave substantial diminution of surface area, moderate changes of acidity and decrease in hds activity for the catalysts with P₂O₅ content higher than 5 wt.%.

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, CoMo–P–Al₂O₃. . , P₂O₅ 5 .%.

     

Nanostructured ruthenium on γ-Al2O3 catalysts for the efficient hydrogenation of aromatic compounds

Free and trioctylamine (TOA)-stabilized ruthenium nanoparticles have been prepared by decomposition of the metal precursor Ru(η⁶-cycloocta-1,3,5-triene)(η⁴-cycloocta-1,5-diene) under mild conditions (room temperature, hydrogen atmospheric pressure). The nanoparticles have been deposited on γ-Al₂O₃ supports having different surface area. The resulting systems are active in the hydrogenation of methyl benzoate to methyl cyclohexanoate with a reaction rate decreasing in the order Ru(TOA)/γ-Al₂ O₃ (high surface area, catalyst D) > Ru(TOA)/γ-Al₂O₃ (catalyst C) > Ru/γ-Al₂O₃ (high surface area, catalyst B) > Ru/γ-Al₂O₃ (catalyst A). Catalysts A-D are long lived and can be reused without loss of activity; they are considerably more active than a commercial ruthenium on γ-Al₂O₃ sample. High Resolution Transmission Electron Microscopy analyses of such systems show that the nanoparticles are homogeneously dispersed on the support and that the size distribution decreases in the order catalyst A, 2.9 nm > catalyst B, 2.8 nm > catalyst C, 2.4 nm > catalyst D, 2.3 nm. Based on the easy hydrogenation of the aromatic ring to the cyclohexane derivative, an efficient synthesis of 4-carbomethoxyformylcyclohexane, important starting material in the preparation of pharmaceutical products, from the largely available methyl 4-formylbenzoate, has been set up in the presence of catalyst D.     

Ni/Al2O3催化甲烷裂解

分别通过浸渍法和共沉淀法制备了不同Ni负载量的Ni/Al2O3催化剂。考察了Ni负载量、制备方法以及反应温度对Ni/Al2O3催化甲烷裂解性能的影响。结果表明,在550℃,浸渍法制备的Ni/Al2O3催化剂,当Ni负载量为20%(质量分数)、Ni金属平均粒径为11.25 nm时,具有最佳的甲烷催化裂解效果,其每摩尔Ni的氢气产量和每克Ni碳产量分别为164 mol和15.30 g。催化剂制备方法对Ni/Al2O3甲烷催化裂解反应有显著影响,相同Ni负载量共沉淀法制备的Ni/Al2O3甲烷催化裂解总体效果要好于浸渍法制备的Ni/Al2O3,而且反应过程中生成的碳纤维较长,管径也较均一。550℃时,共沉淀法制备的Ni负载量为41.2%(质量分数)的Ni/Al2O3催化剂在反应至350 min时,仍保持着30%以上的转化率。     

Catalytic performance in hydrodesulfurization of thiophene and ir investigation of Co and no adsorption over Co?Mo/Al2O3 and Ru?Co?Mo/Al2O3 catalysts

A new Ru–Co–Mo/Al₂O₃ catalyst has been prepared by impregnation of Ru salt as a secondary promoter onto Co–Mo/Al₂O₃ catalyst, and it was found that the Ru–Co–Mo/Al₂O₃ exhibited higher activity than Co–Mo/Al₂O₃ in hydrodesulfurization of thiophene to hydrocarbons. Ir studies on Ru–Co–Mo/Al₂O₃ revealed that the Co and NO adspecies increased significantly in intesnities and displayed a bathochromic shift in frequencies, as compared with Co–Mo/Al₂O₃.

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Ru–Co–Mo/Al₂O₃ Ru, , Co–Mo/Al₂O₃. Co–Mo/Al₂O₃. CO NO, Co Mo, Co–Mo/Al₂O₃. , Mo , Mo³⁺ Mo³⁺ Co Ru–Co–Mo/Al₂O₃.

     

Effect of Fe-modified α-Al2O3 on the properties of Pd/α-Al2O3 catalysts in selective acetylene hydrogenation

The use of nanocrystalline Fe-modified α-Al₂O₃ prepared by sol–gel and solvothermal method as supports for Pd catalysts resulted in an improved catalyst performance in selective acetylene hydrogenation. Moreover, the amount of coke deposits was reduced due to lower acidity of the Fe-modified α-Al₂O₃ supports.     

TiO2对Ni/Al2O3催化剂CO甲烷化性能的影响

采用溶胶凝胶法制备了一系列不同TiO₂含量的TiO₂-Al₂O₃复合载体,并通过浸渍法制备了NiO/TiO₂-Al₂O₃催化剂。分别考察了不同TiO₂含量的NiO/TiO₂-Al₂O₃催化剂及反应温度对CO甲烷化催化性能的影响。实验结果表明,当复合载体中TiO₂质量分数为30%,反应温度为350～450 ℃时,催化剂催化活性较高。利用N₂吸附-脱附(BET)、X射线衍射(XRD)及H₂程序升温还原(H₂-TPR)等手段对催化剂物化性能进行了表征。结果表明,加入适量的TiO₂能抑制镍铝尖晶石NiAl₂O₄物种的生成,改善NiO的表面分散性能,避免大晶粒NiO的形成,也改善了催化剂的还原性能,从而提高催化剂的CO甲烷化活性。     

Al2O3负载Cu,Fe或Ni掺杂氧化钼催化乙苯氧化脱氢（英文）

Molybdenum-based catalysts supported on Al2O3 doped with Ni, Cu, or Fe oxide were synthesized and used in ethylbenzene dehydrogenation to produce styrene. The molybdenum oxide was sup-ported using an unconventional route that combined the polymeric precursor method (Pechini) and wet impregnation on commercial alumina. The samples were characterized by X-ray diffraction (XRD), N2 adsorption-desorption isotherms, temperature-programmed reduction of H2 (H2-TPR), and thermogravimetric (TG) analysis. XRD results showed that the added metals were well dis-persed on the alumina support. The addition of the metal oxide (Ni, Cu, or Fe) of 2 wt% by wet im-pregnation did not affect the texture of the support. TPR results indicated a synergistic effect be-tween the dopant and molybdenum oxide. The catalytic tests showed ethylbenzene conversion of 28%–53% and styrene selectivity of 94%–97%, indicating that the addition of the dopant improved the catalytic performance, which was related to the redox mechanism. Molybdenum oxides play a fundamental role in the oxidative dehydrogenation of ethylbenzene to styrene by its redox and acid–base properties. The sample containing Cu showed an atypical result with increasing conver-sion during the reaction, which was due to metal reduction. The Ni-containing solid exhibited the highest amount of carbon deposited, shown by TG analysis after the catalytic test, which explained its lower catalytic stability and selectivity.     

An efficient and stable Mn–K/CeO2–Al2O3 catalyst for hydrogenation of benzoic acid to benzaldehyde

A Mn–K/CeO₂–Al₂O₃ catalyst for the hydrogenation of benzoic acid (BAC) to benzaldehyde (BAD) has been developed. The catalyst exhibits efficient activity in the reaction and is still stable after 102 h of testing.     

Michael addition of nitromethane to 3-buten-2-one catalyzed by potassium fluoride supported on Al2O3, ZnO, SnO2, sepiolite, AlPO4, AlPO4?Al2O3 and AlPO4?ZnO

The Michael addition of nitromethane to 3-buten-2-one has been carried out in the absence of solvent, using potassium fluoride supported on Al₂O₃, ZnO, SnO₂, sepiolite, AlPO₄, AlPO₄–Al₂O₃ and AlPO₄–ZnO catalysts. We found that KF/ZnO easily performed the Michael addition and thus, ZnO is a better support for the basic reagent than Al₂O₃. Besides, the Michael addition was not successful with AlPO₄ or AlPO₄-metal oxide acidic supports.

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3--2- , , Al₂O₃, ZnO, SnO₂, , AlPO₄, AlPO₄–Al₂O₃ AlPO₄–ZnO. , KF/ZnO .. ZnO, , , Al₂O₃. , , AlPO₄ AlPO₄- .

     

Reduction of an amorphous NiO?Al2O3/SiO2 catalyst by different olefins and hydrogen

By static magnetic measurements it was found that the ability to reduction of an amorphous NiO–Al₂O₃/SiO₂ catalyst decreases in the order: but-2-eneshydrogen isobutene>but-1-ene>propeneethene. The reduction temperatures are significantly higher than the dimerization reaction temperatures.

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, NiO–Al₂O₃/SiO₂ : -2>-1> . .

     

Doping of CoMo?Al2O3 catalyst with Mg and Zn

Effect of Mg (Zn) addition to CoMo–Al₂O₃ catalyst on its activity in hydrogenation of toluene and HDS of thiophene has been determined. These additives decrease the catalyst activity and modify the mechanism of thiophene HDS.

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Mg (Zn) CoMo/Al₂O₃ () . .

     

Pt–Sn/Al2O3 catalyst for the selective hydrodeoxygenation of esters

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Ammoxidation of 3- and 4-picolines over V2O5?SnO2/γ?Al2O3 catalyst

The ammoxidation of 3- and 4-picolines has been studied over V₂O₅–SnO₂/–Al₂O₃ catalysts prepared by surface impregnation technique. Best results were obtained for the generation of cyanopyridines in the temperature range 400–450°C and sub-stoichiometric value with respect to O₂. Catalysts that were calcined above 700°C showed no activity.

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3- 4- V₂O₅–SnO₂/–Al₂O₃, . 400–450°C O₂. , 700 K, .

     

Preparation and Characterization of Storage and Emission Functional Material of Cs2O-doped 12CaO·7Al2O3

We provides a novel approach to generate low-temperature atomic oxygen anions (O^-) emis-sion using the cesium oxide-doped 12CaO·7Al₂O₃ (Cs₂O-doped C12A7). The maximal emis-sion intensity of O^- from the Cs₂O-doped C12A7 at 700 oC and 800 V/cm reached about 0.54 μA/cm², which was about two times as strong as that from the un-doped C12A7(0.23 μA/cm²) under the same condition. The initiative temperature of the O^- emission from the Cs₂O-doped C12A7 was about 500 oC, which was also much lower than the initiative temperature from the un-doped C12A7 (570 oC) in the given field of 800 V/cm. High pure O^- emission close to 100% could be obtained from the Cs₂O-doped C12A7 under the lower temperature (<550oC). The emission features of the Cs₂-doped C12A7, including the emis-sion distribution, temperature effect, and emission branching ratio have been investigated in detail and compared with the un-doped C12A7. The structure and storage characteristics of the resulting material were also investigated via X-ray diffraction and electron paramag-netic resonance. It was found that doping Cs₂ to C12A7 will lower the initiative emission temperature and enhance the emission intensity.     

Selective hydrogenation of furfuryl alcohol to tetrahydrofurfuryl alcohol over Ni/γ-Al2O3 catalysts

Research on Chemical Intermediates - A series of nickel-based catalysts (with &lt;5&nbsp;nm Ni particle size) with γ-alumina as a support (x wt% Ni/γ-Al2O3, x represents the Ni...     

Pd@SiO2/Al2O3的制备及其催化氧化CO性能评价

从Pd纳米粒子出发制备具有核壳结构的Pd@SiO₂纳米粒子,并将其负载于不同形貌Al₂O₃载体上,制备出具有良好CO催化氧化活性的催化剂。以纳米球形Al₂O₃为载体时,Pd@SiO₂/Al₂O₃催化剂活性优于无核壳结构的Pd/Al₂O₃催化剂。将纳米Pd@SiO₂负载到球形和菱形Al₂O₃上,制备出Pd@SiO₂/Al₂O₃催化剂。结果表明:具有较大比表面积的Al₂O₃载体(球形)有利于Pd@SiO₂的分散,且SiO₂层可以抑制Pd粒子的团聚,能在一定程度上改善催化活性。而较小比表面积的载体(菱形)上出现了Pd@SiO₂的团聚,表现出较低的CO氧化活性,但在降低负载量后,CO氧化活性明显提高。该结果为推动新型热稳定、高效纳米三效催化剂的研发具有一定的启示意义。     

α-Phenylselenenylation of aldehydes and ketones with diphenyl diselenide mediated by KF/Al2O3

The utility of KF/Al₂O₃ for the synthesis of α-phenylseleno aldehydes and ketones from the corresponding aldehydes or ketones and diphenyl diselenide has been investigated. Simple stirring of a mixture of aldehyde or ketone and diphenyl diselenide in the presence of KF/Al₂O₃ at room temperature selectively produces the corresponding α-phenylseleno aldehyde or ketone in good to excellent yields.