Hydrogenation of dioctyl phthalate over a Rh-supported Al modified mesocellular foam catalyst

Abstract

A new catalyst was developed for selective hydrogenation of dioctyl phthalate (DOP) to produce the environmentally friendly plasticizer di(2-ethylhexyl)hexahydrophthalate (DEHHP) by incorporating rhodium via chemical fluid deposition into an aluminum-modified mesocellular foam (MCF). The Al-modified MCF containing a Si/Al molar ratio of 5 and 1 wt% Rh achieved 100% conversion of DOP to DEHHP with no side products at 80 °C and 68 atm H₂ pressure in one hour reaction time. On the other hand, a 1 wt% Rh/MCF catalyst without any surface modification with Al yielded only 29% conversion. The interaction of Rh with the support became stronger when Al was incorporated onto the MCF support. An effective control of the acidity provided by Al by closely monitoring the Si/Al ratio was key in improving the catalytic activity of the Rh/Al-MCF catalysts.