Catalytic behavior of palladium in the hydrogenation of edible oils II. Geometrical and positional isomerization characteristics

The geometrical isomerization characteristics of 5% Pd/alumina were investigated using response surface methodology. From the response surface, it was observed as expected that more trans isomers were formed at lower pressures and higher temperatures. A doubling of the metal concentration from 50 to 100 ppm resulted in a small increase in isomerization in soybean oil, while for canola oil the same increase had a larger effect, especially at lower pressures. Similarly, an increase in temperature increases geometrical isomerization, especially at lower pressures, but the effect is more pronounced for canola than for soybean oil. Positional isomers were determined by oxidative ozonolysis in BF 3 ‐MeOH and subsequent GLC analysis. Higher pressures suppressed positional isomerization. The effect of various catalyst supports on positional isomerization was also investigated.