SELECTIVE HYDROGENATION OF 3-NITROSTYRENE TO 3-VINYLANILINE OVER PT-BASED BIMETALLIC CATALYSTS

Abstract

The Pt-based bimetallic catalysts on degussa P25 titanium dioxide were synthesized by co-impregnation method with metal from the 4th row of periodic table such as Cr, Fe, Co, Ni, Cu, Zn, and Ga. The catalytic activities were tested in the liquid-phase selective hydrogenation of 3-nitrostyrene (3-NS) to 3-vinylaniline (3-VA) under 2 MPa of H2 and 50ºC. I was found that the 0.5Pt-xFe/TiO2 series exhibited superior NS conversion and higher 3-VA selectivity than the monometallic Pt catalyst. The Pt-Co(0.3-0.5%) and Pt-Ga(0.2-0.5%) also showed improved catalytic performances. The activity of the bimetallic Pt-based catalysts did not follow the CO-chemisorption trend due probably to the Pt-alloy formation and/or the coverage of Pt active site by the 2nd metal. However, the H2-TPR results showed that the reducibility of Pt oxide was easier for the bimetallic catalysts and the XRD results revealed the presence of amorphous phase when Fe, Co, or Ga were added to the Pt catalysts. This could be the reason for higher VA selectivity of these catalysts. The 0.5Pt-0.5Fe/TiO2 showed the best catalytic performances which gave the lowest undesire product (3-ethylnitrobenzene) about 0.2 % with the highest yield of 3-VA at 78%.