Treatment of chlorophenols-bearing wastewaters throughhydrodechlorination using Pd/activated carbon catalysts

摘要

The catalytic hydrodechlorination of aqueous 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol solutions overrna Pd/activated carbon catalyst (0.5 % w/w Pd) was studied in a fixed bed reactor. The reactor was fed with a 100rnmg/L solution of chlorophenol and a H2/N2 (1:1, vol.) stream at a 100 mL/min flow rate. The ranges studied forrntemperature, pressure and chlorophenol solution flow rate were 25-100 ℃, 0.8-5.0 bar and 0.25-1.0 mL/min,rnrespectively. Chlorophenols conversion was found to peak for pressure values c.a. 1.4 bar. In this condition, the risernin reaction temperature led to higher conversion. At high space time the reactants conversion and the selectivityrntowards end reaction products was enhanced. At the optimum conditions, a 2-chlorophenol conversion of 95% wasrnreached, whereas conversions of 73 and 80% were achieved for 4-chlorophenol and 2,4-chlorophenol. As result of therntreatment the toxicity of the initial solutions was substantially reduced.