Hydrogenation of alkenes on a nickel-tungsten-alumina catalyst

Abstract

Eleven C2 to C8 alkenes were hydrogenated on a reduced sulphided industrial nickel-tungsten catalyst. Kinetics of the reaction was investigated in detail for ethylene and data were correlated by different equations. Best fit was obtained by three equations of the Langmuir-Hinshelwood type and these were used to describe hydrogenation of the other alkenes. Logarithms of the rate constants obtained were correlated linearly with the sum of steric constants E0s of substituents of semihydrogenated state R1R2R3C-*. Also adsorption coefficients of alkenes were structure dependent, increased with molecular weight of alkene and correlated roughly with boiling points.

Substituent Effects

“…This expression has been used by van Bekkum, Kieboom and van de Putte [8] for correlation of the data of rates of hydrogenation of substituted acetophenones (Fig. When these extended expressions are used for a sufficiently reliable set of data, it is sometimes found that one of the proportionality factors (ρ * , ρ, s, r) is negligibly small and the corresponding term can be omitted from the equation which then reduces to a type (7) relationship. When these extended expressions are used for a sufficiently reliable set of data, it is sometimes found that one of the proportionality factors (ρ * , ρ, s, r) is negligibly small and the corresponding term can be omitted from the equation which then reduces to a type (7) relationship.…”

“…For the CoO − MoO 3 /Al 2 O 3 and sulfided NiO − WO 3 /Al 2 O 3 catalysts [7,71], the only correlation of rate constants was obtained with the sum of steric constants E • s for the alkyl groups on the carbon atom which remains bonded to the catalyst in the halfhydrogenated state. For the CoO − MoO 3 /Al 2 O 3 and sulfided NiO − WO 3 /Al 2 O 3 catalysts [7,71], the only correlation of rate constants was obtained with the sum of steric constants E • s for the alkyl groups on the carbon atom which remains bonded to the catalyst in the halfhydrogenated state.…”