Structural and textural evolution of Ni/γ-Al2O3 catalyst under hydrothermal conditions

Li, Haitao; Xu, Yixiang; Gao, Chunguang; Zhao, Yongxiang

doi:10.1016/j.cattod.2010.07.015

Cited by 44 publications

(28 citation statements)

References 33 publications

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“…The catalyst used for this process was the 17%Ni/Al 2 O 3 prepared by the wet impregnation method [15]. In this work, a similar catalyst (17%Ni/Al 2 O 3 ) was prepared for comparison by the incipient wetness impregnation method.…”

Section: Preparation Of Catalystsmentioning

confidence: 99%

“…Thus, the catalysts must withstand the severe hydrothermal environments for the hydrogenation reactions with water as a solvent or a product. The supports may be hydrolyzed, causing the collapse of pore structures and leading to the aggregation of supported active components and finally the deactivation of catalysts [15]. Thus, it is important to develop the highly active and hydrothermally stable catalysts.…”

Section: Introductionmentioning

confidence: 99%

“…However, the hydrothermal stability of Ni/ Al 2 O 3 catalysts was poor, due to the easy hydration of Al 2 O 3 , leading to the significant decrease of surface areas and pore volumes and thus the aggregation of supported nickel particles and the loss http://dx.doi.org/10.1016/j.jcis.2015.01.081 0021-9797/Ó 2015 Elsevier Inc. All rights reserved. of catalytic activities [15]. In order to improve the hydrothermal stability of Ni/Al 2 O 3 catalysts, it is necessary to improve the hydrothermal stability of the Al 2 O 3 support.…”

Section: Introductionmentioning

confidence: 99%

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Preparation of highly active and hydrothermally stable nickel catalysts

Chen

Shen

2015

Journal of Colloid and Interface Science

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Section: Preparation Of Catalystsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Preparation of highly active and hydrothermally stable nickel catalysts

Chen

Shen

2015

Journal of Colloid and Interface Science

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“…Water on the catalysts surface typically converts Lewis acid sites to Brønsted ones, which were found to deteriorate the selectivity in terms of the cyclohexanone oxime formation [9,10]. The hydroxyl groups, created by the hydration of Lewis acid sites can be reversibly dehydrated upon calcination, thus restoring the original Lewis acidity [17] Another effect of water, formed as a reaction product, is that it shifts the equilibrium of Schiff base formation back to cyclohexylamine and cyclohexanone (Scheme S1) [6]. Thus, water decomposes the Schiff base on the catalysts surface and-as the Schiff base readily undergoes condensation reactions [18]-prolongs the lifetime of the catalyst.…”

Section: Extraction Of the Adsorbed Reaction Productsmentioning

confidence: 99%

Towards the mechanism of the oxidation of cyclohexylamine by molecular oxygen over alumina-based catalysts

Horváth

Kaszonyi

Rakottyay

et al. 2015

Reac Kinet Mech Cat

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The oxidation of cyclohexylamine with molecular oxygen over a heterogeneous catalyst is an attractive one-step route to prepare a commercially important cyclohexanone oxime. The effect of the reaction conditions on the conversion of cyclohexylamine during its oxidation by molecular oxygen and on the selectivity of cyclohexanone and cyclohexanone oxime formation was investigated over heterogeneous catalysts (alumina and alumina supported silicotungstic acid). The present work is aimed at the enhancement of the cyclohexanone oxime yield, for which the optimized conditions were found as: reaction temperature of 180°C, LHSV of cyclohexylamine 1 ml g -1 h -1 , oxidant 33 % O 2 in nitrogen with a total GHSV of 24 ml min -1 . Cyclohexanone, formed from cyclohexylamine, reacts with cyclohexylamine to N-cyclohexylidenecyclohexylamine, their Schiff base. The most intense formation of cyclohexanone was observed in the initial period of the catalytic tests. Carbonaceous deposits, responsible for the catalyst deactivation, are formed mainly from the Schiff base; their amount increases by time on stream, and the rate of their formation correlates with the concentration of oxygen in the reaction mixture, as well as with the formation rate of cyclohexanone and the Schiff base. Injection of water to the reactant stream prolongs the catalyst lifetime and reduces the tar formation. However, it deteriorates the catalysts activity and selectivity. The supposed mechanism of cyclohexylamine oxidation is discussed.Electronic supplementary material The online version of this article (

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“…1,4-Butanediol (BDO) is one of the most important organic and ne chemical raw materials; its derivatives are widely used in medicine, ber and engineering plastics. [1][2][3][4][5][6] The main process of BDO production is the Reppe method, which includes two steps; 7,8 the production of 1,4-butynediol (BYD) from acetylene and formaldehyde and the hydrogenation of 1,4-butenediol (BED) to prepare 1,4-butanediol occur by two sequential processes, namely BYD to BED and BED to BDO. However, depth hydrogenation of BED is accompanied by side reactions, including double migration, hydrogenolysis, and isomerization, to form 4-hydroxybutanal (HALD), tetrahydrofuran, 1-ene-3-octanol, 2-hydroxytetrahydrofuran (HTHF), and 2-(4hydroxybutoxy)-tetrahydrofuran (HBOTHF) by-products.…”

Section: Introductionmentioning

confidence: 99%