Comparison of C═C Bond Hydrogenation in C-4 Unsaturated Nitriles over Pt/Alumina

Abstract

Abstract.The hydrogenation of allyl cyanide (but-1-ene-4-nitrile, AC), trans-and cis-crotononitrile (Eand Z-but-2-ene nitrile, TCN and CCN), and methacrylonitrile (2-cyano-1-propene, MCN) were studied, both singly and competitively, over a Pt/alumina catalyst in the liquid phase.Each unsaturated nitrile only underwent C=C bond hydrogenation: no evidence was found for the formation of the saturated or unsaturated amine. The non-conjugated allyl cyanide was found to be the most reactive unsaturated nitrile. Activation energies for the hydrogenation of the C=C bond in AC and MCN were determined giving values of 64±7 kJ.mol -1 for AC and 37±4 kJ.mol -1 for MCN. The reaction was zero order for both nitriles. Competitive hydrogenations revealed that not only does allyl cyanide react preferentially over the other isomers but that it also inhibits the hydrogenation of the other isomers. When all four nitriles were simultaneously hydrogenated, inhibition effects were easily seen suggesting that in terms of strength of bonding to the surface an order of AC > CCN > TCN ~ MN can be generated.

SiO2-Modified Pt/Al2O3for Oxidative Dehydrogenation of Ethane: A Preparation Method for Improved Catalytic Stability, Ethylene Selectivity, and Coking Resistance

“…Platinum­(Pt)-based catalysts belong to one of the most frequently used types of catalyst in chemical industry as well as in fundamental research. Especially they are widely involved in the catalytic processes like hydrogenation of CC , or CO bond, , dehydrogenation , of alkanes, partial , and complete oxidation of alkanes, oxidation of CO, , hydrogenolysis, , and aqueous phase reforming − of bioderivatized alcohols or polyols. Parts of these processes are of great economic significance.…”