Date of Award

1-1-1980

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Abstract

The codeposition of nickel with arenes by the metal atom cocondensation (MAC) technique at -196(DEGREES)C results in a mixture of Ni-arene complex and Ni clusters in the solid matrix. This matrix, when allowed to melt and flow to the bottom of the metal-atom reactor, forms a nickel slurry or deposits onto a support (such as Al(,2)O(,3)), if present. Both nickel powders, isolated from Ni-arene slurries, and the Ni-arene/Al(,2)O(,3) from Ni-arene deposition are active catalysts.The activity and selectivity for MAC prepared Ni-PhCH(,3), Ni-1,3,5-Ph(CH(,3))(,3), Ni-PhCF(,3), and Ni-m-Ph(CF(,3))(,2) in both supported and unsupported form, were examined for toluene hydrogenation and hydrodealkylation activity and also for alkane hydrogenolysis activity. These studies were conducted in a static high pressure autoclave and in a pulse-flow microreactor. Comparisons were made to Raney nickel and a conventionally prepared Ni/Al(,2)O(,3) catalyst. Additional activity studies were conducted in a recirculation flow microreactor with comparisons of supported and unsupported Ni-PhCH(,3) to other catalysts such as Raney nickel for 1-butene hydrogenation and isomerization and also for 1,3-butadiene hydrogenation. Maximum activities per gram of nickel were found at low % nickel compositions in Ni-PhCH(,3)/Al(,2)O(,3). The maximum for toluene hydrogenation was found at 0.32% Ni, while 2% Ni gave a maximum activity for methylcyclopentane hydrogenolysis. The cause of this activity effect is thought to be either an optimum particle size or possible active surface complex or complex cluster formation.Characterization of the prepared catalysts involved ESCA, FMR, thermal desorption-pyrolysis (TD-P), and hydrogen induced desorption. ESCA studies on Ni-PhCF(,3) and 3.1% Ni-PhCF(,3)/Al(,2)O(,3) indicated NiF(,2) as the predominant fluorine species. Desorption studies showed extensive hydrocarbon fragmentation of any retained hydrocarbon in the catalysts, with C(,1) species predominating in the desorbed materials.Hydrogen chemisorption, TEM, X-ray line broadening, and SAXS studies were conducted to determine particle and crystallite sizes. Ni-PhCF(,3) was found to have the smallest crystallite size (13 (ANGSTROM)), but this probably was due to the inhibition of clustering byNiF(,2) formation. The smallest particle size (62 (ANGSTROM)) was found for 2% Ni-PhCH(,3)/Al(,2)O(,3), but was possibly much smaller due to considerable slow H(,2) uptake component in chemisorption.A literature survey of relevant information for supported nickel catalyst preparation and characterization was also compiled.

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