TPR studies of the effects of preparation conditions on supported nickel catalysts

Mile, B.; Stirling, Diane; Zammitt, M.A.; Lovell, A.; Webb, M. B.

doi:10.1016/0304-5102(90)85212-z

Cited by 121 publications

(91 citation statements)

References 17 publications

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“…Four peaks were identified (Table 1) for the former case: a small ill-defined peak at T, , = 528 K, which has been ascribed (45) to an endothemic phase transition from rhombohedra1 to cubic NiO which occurs simultaneously with reduction; a minor (573 K) and a major (610 K) peak, which can be attributed to the process H, + NiO + H20 + Ni where the minor peak (with a T, , , similar to that for bulk NiO) is associated with the reduction of very weakly interacting NiO and the higher temperature peak represents the reduction of NiO which interacts to a greater extent with the canier; and a broad peak with T, , = 693 K, which may be due to the more difficult reduction of a surface nickel silicate species. The reduction of the precalcined sample generated a small peak at T,, = 503 K, which is thought to be due to the reduction of traces of Ni(II1) oxide (43), and a broad peak at T, , , = 658 K with a shoulder, which can be considered to represent the reduction of both surface NiO and nickel silicate. As with the HPD catalysts, the introduction of the calcination step shifted the T, , of the principal peak to a higher value.…”

Section: Resultsmentioning

confidence: 99%

“…The calcination step, in effect, removed the low temperature peak and stabilized the unreduced surface nickel, possibly by eliminating some of the structural water of the hydrosilicate species and making it more difficult to reduce. In contrast to the HPD technique, catalyst preparation by impregnation has received considerable attention (41)(42)(43)(44). The TPR profiles generated during the direct reduction and precalcination-reduction of the impregnated catalyst are shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

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The role of catalyst activation in the enantioselective hydrogenation of methyl acetoacetate over silica-supported nickel catalysts

Keane¹

1994

Can. J. Chem.

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A range of Ni-Si02 catalysts have been prepared by homogeneous precipitation-deposition and impregnation techniques and modified with aqueous solutions of R-(+)-tartaric acid (TA) to induce enantioselectivity in the asymmetric hydrogenation of a prochiral P-ketoester (methyl acetoacetate) to a P-hydroxyester ((R)-(-)-methyl3-hydroxybutyrate). The effects of catalyst precursor preparation, nickel loading, and precalcination on the reduction of the precursor were examined and the nature of the resultant nickel particle size distribution is described. The influence of metal-support interactions on the uptake of TA was investigated and data on the corrosive metal leaching and the consequent changes in metal dispersion are presented. Modification of the catalysts with TA not only induced enantioselectivity, but also increased the turnover frequency by up to 15 times that observed for the unmodified surface. The amount of TA adsorbed and the fractional surface coverage by TA is related to the degree of enantiodifferentiation. The effects of variations in supported nickel metal particle sizes (in the overall range of 1.4-13.6 nm) on the reaction rate and enantioselectivity were examined; while the selectivity was independent of metal particle size, the rate of hydrogenation was found to be structure sensitive and a correlation between reaction rate sensitivity and particle size is presented.MARK A. KEANE. Can. J. Chem. 72,372 (1994). On a prCparC une sene de catalyseurs Ni-Si02 par des techniques de prCcipitation-dCp6t et d'imprkgnation homogbnes et on les a modifiCs avec des solutions aqueuses d'acide R-(+)-tartrique (AT) dans le but d'induire de I'CnantiosClectivitC dans l'hydrogCnation asymCtrique d'un ester P-cCtonique prochiral (acetoacetate de mCthyle) en ester P-hydroxylC, (R)-(-)-3-hydroxybutyrate de mCthyle. On a CvaluC les effets de la prCparation des prCcurseurs des catalyseurs, de la quantitC de nickel et de la prCcalcination sur la reduction du prCcurseur et on dCcrit la nature de la distribution des grosseurs des particules de nickel qui en rCsulte. On a CtudiC l'influence des interactions mCtal-support sur la quantitC d'AT adsorb6 et on prCsente des donnCes concernant le lixiviation par des mCtaux corrosifs et sur les changements qui en rCsultent sur la dispersion du mCtal. La modification des catalyseurs par I'AT n'induit pas seulement de l'CnantiosClectivitC, le frCquence dlCchange est 15 fois plus rapide que sur une surface non modifiCe. La quantitC d'AT adsorbke et la fraction de la surface qui est couverte sont relikes au degrC d'Cnantiodiffkrentiation. On a examink les effets des variations dans les grosseurs des particules du nickel support6 (grosseurs allant de 1,4 B 13,6 nm) sur la vitesse de rCaction et sur llCnantiosClectiviC; alors que l'on a trouvC que la sClectivitC est indCpendante de la grosseur des particules mktalliques, la vitesse d'hydrogknation est sensible ? I la structure et on prCsente une corrClation entre la sensibilitC de la vitesse rkactionnelle et la grosseur des particules.[...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

The role of catalyst activation in the enantioselective hydrogenation of methyl acetoacetate over silica-supported nickel catalysts

Keane¹

1994

Can. J. Chem.

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“…It has been reported [24] that the nickel oxide powders showed a single reduction peak at 300-400°C. In [25] Brynmor Mile reported that there were two kinds of the reducible nickel oxide on SiO 2 support. One resembling bulk NiO located mainly in the small pores (\9 nm) has negligible interaction with the silica and easily to be reduced at low temperature.…”

Section: Catalysts Characterizationmentioning

confidence: 98%

Catalytic Performance of Monolithic Foam Ni/SiC Catalyst in Carbon dioxide Reforming of Methane to Synthesis Gas

Liu

Zhang

et al. 2007

Catal Lett

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Carbon dioxide reforming of methane to synthesis gas has been investigated with Ni catalysts supported on monolithic foam SiC, which were prepared by the initial wetness impregnation method. The catalyst of 7 wt%Ni/ SiC was verified to be the best one in different Ni content catalysts. Compared with other catalysts such as 7 wt%Ni/ SiO 2 and 7 wt%Ni/Al 2 O 3 , the 7 wt%Ni/SiC catalyst exhibited not only the highest activity but also remarkable stability and excellent coke resistance during 100 h reaction. Furthermore, the conversion of CO 2 and CH 4 remained at about 96% and 94%, respectively in 100 h reaction time. The structure and properties of the catalysts were characterized by BET, XRD, H 2 -TPR, XPS and TEM techniques.

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“…TPR experiments were carried out to explore the extent of reducibility of nickel species and the metal-support interactions [55]. The reduction profiles of the calcined Ni/SBA-15 catalysts are shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Hydrogenation of levulinic acid with and without external hydrogen over Ni/SBA-15 catalyst

et al. 2018

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A series of Ni/SBA-15 catalysts were prepared by impregnation method for the hydrogenation of levulinic acid (LA) to γ-valerolactone in a fixed bed reactor at atmospheric pressure. The catalysts were characterized by XRD, TPR, AAS, Pulse chemisorption, SEM-EDAX, TEM, BET Surface area and XPS. The catalyst 30 wt% Ni/SBA-15 exhibited excellent catalytic performance (97% yield) at 250 °C due to the presence of superior number of active surface Ni species. While 30 wt% Ni/ SiO 2 catalyst showed lower catalytic activity (87% yield) at about similar conversion. The co-feeding of formic acid (FA) and water (impurities) with levulinic acid was also evaluated over 30 wt% Ni/SBA-15 which yielded excellent levulinic acid conversion. The noteworthy results were obtained at a molar ratio of FA/LA = 5. The constant catalytic activity during 10 h experiment with an external H 2 flow has showed the sturdiness of the Ni/SBA-15 catalyst. On the other hand, a slight decrease in conversion as well as yield during the time-on-stream in the absence of external H 2 flow was attributed to the accumulation of carbon species on the catalyst surface.

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TPR studies of the effects of preparation conditions on supported nickel catalysts

Cited by 121 publications

References 17 publications

The role of catalyst activation in the enantioselective hydrogenation of methyl acetoacetate over silica-supported nickel catalysts

The role of catalyst activation in the enantioselective hydrogenation of methyl acetoacetate over silica-supported nickel catalysts

Catalytic Performance of Monolithic Foam Ni/SiC Catalyst in Carbon dioxide Reforming of Methane to Synthesis Gas

Hydrogenation of levulinic acid with and without external hydrogen over Ni/SBA-15 catalyst

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