Degradation of phenylamine by catalytic wet air oxidation using metal catalysts with modified supports

Abstract

The effect of acid treatments with HCl and HNO₃ on the surface area and surface chemistry of three granular activated carbons was studied. These supports were characterized and the hydrochloric acid treatment leads to the best activated carbon support (AC2-C). The catalytic behavior of Pt, Ru and Fe (1 wt.%) supported on granular activated carbon treated with HCl was tested in the phenylamine continuous catalytic wet air oxidation in a three-phase, high-pressure catalytic reactor over a range of reaction temperatures 130–170ºC and total pressure of 1.0–3.0 MPa at LHSV = 0.4–1 h⁻¹, whereas the phenylamine concentration range and the catalyst loading were 5–16 mol.m⁻³ and 0.5–1.5 g, respectively. Activity as well as conversion varied as a function of the metal, the catalyst preparation method and operation conditions. Higher activities were obtained with Pt incorporated on hydrochloric acid -treated activated carbon by the ion exchange method. In steady state, approximately 98% phenylamine conversion, 77% of TOC and 94% of COD removal, was recorded at 150ºC, 11 mol m⁻³ of phenylamine concentration and 1.5 g of catalyst, and the selectivity to non-organic compounds was 78%. Several reaction intermediaries were detected. A Langmuir–Hinshelwood model gave an excellent fit of the kinetic data of phenylamine continuous catalytic wet air oxidation over the catalysts of this work.

Keywords:

• Activated carbon
• catalytic wet air oxidation
• metal catalysts
• phenylamine

Funding

The authors gratefully acknowledge the financial support from Ministerio de Economía and Competitividad, MINECO (CTQ2011-27169) and by Comunidad de Madrid through REMTAVARES Network (S2013/MAE-2716).