Influence of agitator design and catalyst concentration on partial hydrogenation of sunflower oil

Abstract

In this study, lab-scale hydrogenation of sunflower oil was conducted at 190 7C and 2 bar using two different catalyst types at varying concentrations and two different agitator designs (surface gassing and hollow shaft) at varying power inputs. At identical power input and reaction conditions, the reaction rate with the hollow-shaft agitator was 1.68 times higher than with surface gassing agitation. The catalyst concentration had to exceed a certain feedstock-dependent threshold value of 25 ppm Ni in order to start the reaction. At low catalyst concentration, the reaction rate increased proportionally with increasing catalyst concentration. When hydrogen consumption became higher than the available mass transfer provided by the agitation system, the reaction time became less dependent on the catalyst concentration. For the hollowshaft agitator, this situation was observed at a reaction rate of 3.7 DIV/min, where trans formation was at its maximum with more than 40% trans fatty acids in partially hydrogenated sunflower oil with IV 65. The region in which hydrogen mass transfer did not limit the reaction rate could be extended by more efficient agitation design or increased agitation power. In this way, productivity can be increased and trans formation can be controlled in a better way when compared to hydrogenation with a less efficient agitator.