Dimethyl adipate hydrogenation at presence of Pt based catalysts

Abstract

Dimethyl adipate hydrogenations catalyzed by Pt/Al 2O 3 and Pt/TiO 2 have been studied. Catalysts were prepared with the conventional impregnation method. Physical–chemical characterization of the catalytic systems was made with the use of different techniques: N 2 and H 2 sorption, scanning electron microscopy (SEM), energy-dispersive electron (EDS) probe X-ray analysis, temperature programmed reduction (TPR) and inductively coupled plasma optics emission spectrometry (ICP-OES). Metals dispersion in the catalysts is directly related to the superficial area of the supports, and partially covered particles (in the case of the TiO 2) can be present. Support modifies the behavior of metals in its surface for different ways: SMSI effect (TiO 2) or acidity (Al 2O 3). The catalyst supported on Al 2O 3 is more active, reaching 52.91% conversion after 10 h of reaction, while at the same period of time, the catalyst supported on TiO 2 converted only 15.56% of the substrate. Methyl caproate, adipic acid mono-methyl ester and caprolactone were obtained as main products by Pt/Al 2O 3 catalyst. These products indicate that carboxylic groups have not been activated enough, leading to formation of significant amount of hydrogenation products different from 1,6-hexanediol (diol). Pt/TiO 2 catalyst obtained methyl caproate, caprolactone, hexane and diol, where hexane formation occurred from methyl caproate. Diol formation occurred after 5 h of reaction and it indicates participation of platinum and TiO 2 as active catalytic sites.