Canola oil was hydrogenated on an industrial nickel catalyst at 180˝C under a wide range of pressures from 1.5 to 21 bar(a). The effect of hydrogen pressure on the hydrogenation characteristics and fatty acids profile was investigated. The hydrogenation kinetics were described by a simplified three-step model including linolenic acid. The apparent rate constants for the particular reaction steps (hydrogenation, isomerization) k x as well as rate constants k x0 and reaction orders in hydrogen were determined. The results reveal that with the increasing pressure an increase of values of all rate constants was observed, with the largest increase being observed for the rate constant of hydrogenation of monoenes to stearic acid (about 20 times). Moreover, with the increasing pressure the isomerization rate of cis dienes to trans dienes was found to become lower than the dienes hydrogenation rate. Analogously, the cis/trans monoenes isomerization rate was also found to decrease with the increasing pressure. The reaction orders of the hydrogenation steps with respect to hydrogen were in the range of 0.35 to 1.1. The kinetic model was verified by comparsion of predicted fatty acids contents with the experimental data of fatty acids profiles. It emerged that a simplified kinetic model proposed can be utilized to simulate the course of the hydrogenation process and concentrations of fatty acids at a certain iodine value.

A proper selection of steam reforming catalyst geometry has a direct effect on the efficiency and economy of hydrogen production from natural gas and is a very important technological and engineering issue in terms of process optimisation. This paper determines the influence of widely used seven-hole grain diameter (ranging from 11 to 21 mm), h/d (height/diameter) ratio of catalyst grain and S h /S t (hole surface/total cylinder surface in cross-section) ratio (ranging from 0.13 to 0.37) on the gas load of catalyst bed, gas flow resistance, maximum wall temperature and the risk of catalyst coking. Calculations were based on the one-dimensional pseudo-homogeneous model of a steam reforming tubular reactor, with catalyst parameters derived from our investigations. The process analysis shows that it is advantageous, along the whole reformer tube length, to apply catalyst forms of h/d = 1 ratio, relatively large dimensions, possibly high bed porosity and S h /S t ≈ 0.30-0.37 ratio. It enables a considerable process intensification and the processing of more natural gas at the same flow resistance, despite lower bed activity, without catalyst coking risk. Alternatively, plant pressure drop can be reduced maintaining the same gas load, which translates directly into diminishing the operating costs as a result of lowering power consumption for gas compression.