Hydrogenation of nitriles on a well-characterized nickel surface: From surface science studies to liquid phase catalytic activity measurements | | Posted on:1994-01-02 | Degree:Ph.D | Type:Thesis | | University:University of California, Berkeley | Candidate:Gardin, Denis Emmanuel | Full Text:PDF | | GTID:2471390014493260 | Subject:Chemistry | | Abstract/Summary: |  PDF Full Text Request | | The work described in this thesis is aimed at providing information about the mechanism and factors affecting the performance of nickel-based catalyst in nitrile hydrogenation reactions. The catalytic surface is modeled by a nickel single crystal surface which can be cleaned and characterized in an ultra-high vacuum environment. In the first part, the techniques of surface science are used to characterize the bonding of adsorbates and to identify surface intermediates which might play a role during the hydrogenation of nitriles. In the second part, liquid-phase hydrogenation reactions of olefins are carried out on a polycrystalline platinum foil prepared in UHV.;The adsorption of acetonitrile on Ni(111) leads to an ordered (2 x 2) overlayer. Low-energy electron diffraction (LEED) intensity vs. energy (I-V) curves for this structure have been measured and analysed using an automated search method based on the Tensor LEED approximation. The adsorbed acetonitrile is bonded to the surface by both carbon and nitrogen with the C-N axis almost parallel to the metal surface. The rehybridized acetonitrile on the surface is non-linear with a C-C-N angle estimated at 123;The bonding and geometry of methylamine ;The proposed dehydrogenation pathway of ethylamine was also examined by extended Huckel calculations. The binding energies of the decomposition products and intermediate surface species formed on Ni(111) from adsorption of ethylamine ;The thermal decomposition of these simple amines on Ni(111) produces a ;In order to correlate the liquid phase activity and selectivity of a catalytic surface with its structure and composition, we have built and tested the first liquid phase hydrogenation cell coupled to an ultra-high vacuum surface analysis chamber. This novel apparatus is tested with the hydrogenation of cyclohexene to cyclohexane on a polycrystalline platinum foil, and then with the hydrogenation of 1-hexene to n-hexane. The hydrogenation of propionitrile is also attempted but no activity is detected. Hydrogenations of olefins and nitriles were also carried out on Ni(111) but no products could be formed.;We finally review the techniques of surface science that have been applied to molecular level studies at both solid-gas and solid-liquid interfaces. (Abstract shortened by UMI.). | | Keywords/Search Tags: | Surface, Hydrogenation, Liquid phase, Nitriles, Catalytic, Activity | | PDF Full Text Request | Related items |
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