Highly stable platinum monolith catalyst for the hydrogenation of vegetable oil

Abstract

In the present work, a novel structured platinum catalyst where the Pt is supported on an anodized aluminum monolith was studied for the hydrogenation of sunflower oil. The catalytic tests were carried out in a monolithic stirred semi-batch reactor at temperatures between 433 and 473 K, and hydrogen pressures from 2.7 to 5.4 atm. The monoliths were prepared using H2PtCl6 and Pt(C5H7O2)2 metal precursors and characterized by temperature programmed reduction, N2 adsorption isotherms, H2 chemisorption, scanning electronic microscopy, inductively coupled plasma-atomic emission spectroscopy, and ultrasound adherence tests. Response surface methodology was used to study the relationship between the process variables and C = C conversion, concentration of trans-isomers and selectivity toward monosaturated (S1) and saturated (S2) fatty acids. The catalysts showed to be active, reaching a conversion of 18% at 120 min. The H2PtCl6 impregnated monolith exhibited low selectivity towards trans-isomer formation, maintaining its initial catalyst activity after 40 consecutive uses, without modifications on S1 and S2. The results indicated that platinum monolith catalysts could be an affordable alternative to commercial Ni catalysts, removing the filtration and bleaching stages, hence reducing the processing costs.