Liquid-phase catalytic hydrodechlorination of perchloroethylene

Abstract

The reactivity of pure hydrogen, isopropanol and formic acid as reducing agents was assessed for the liquid-phase perchloroethylene (PCE) hydrodechlorination (HDC) over 0.8% Pd/TiO2 sol-gel under mild reaction conditions. Additionally, the effect of the amount of water and sodium hydroxide added into the reaction mixture were studied. Fresh and used catalysts were characterized by AAS, H2-chemisorption, N2 adsorption-desorption, DRX, H2-TPR, TGA-DTG, UV-Vis DRS, NH3-TPD and TEM. Best results were obtained with hydrogen and isopropanol as reductants. The addition of NaOH signifi cantly increases the conversion of PCE with the above reducing agents. However, an excess of NaOH negatively affects the HDC reaction. Characterization of fresh and used catalysts reveals certain changes, such as: surface area and Pd dispersion decrease, increased superfi cial acidity and Pd particle size. However, some characteristics like Pd loading, TiO2 crystalline structure and Pd oxidation state remained.

Keywords

• catalytic hydrodechlorination
• perchloroethylene
• pure hydrogen
• isopropanol
• formic acid
• palladium