Combined degradation method for processing high concentration halogenated phenol compounds

[0022] Example 1 Preparation of Hydrodehalogenation Catalyst

[0023] A certain amount of palladium chloride is dissolved in concentrated hydrochloric acid, diluted with water and then immersed in activated carbon, and then evaporated to dryness under constant stirring. The obtained solid is crushed into powder, reduced by hydrogen gas, and finally sealed and stored to obtain palladium/carbon catalysts with different contents. Palladium/carbon catalysts with different contents are listed in Table 1. Then, supported catalysts with different carriers and different active ingredients can be prepared. The prepared catalysts are listed in Table 1.

[0024] Table 1 Different carriers and catalysts with different active components

[0025]

[0026] Example 2 Preparation of Raney Ni catalyst

[0027] In a 4L beaker, dissolve 380g of sodium hydroxide in 1.5L of distilled water, stir, and cool to 10°C on an ice bath. Under stirring, add 300g of nickel-aluminum alloy into the lye in small batches, and the speed of addition should be controlled so that the temperature of the solution does not exceed 25°C (on an ice bath). When all the additions are complete (about 2 hours), stop stirring, remove the beaker from the ice bath, and allow the reaction solution to rise to room temperature. When hydrogen generation is slow, you can slowly heat it on a boiling water bath (avoid heating too fast to prevent excessive bubbles and overflow of the reaction liquid), until the bubble generation slows down again (about 8-12 hours, at which time the volume of the solution) It should be maintained basically constant by adding distilled water). Then let the nickel powder settle, and pour off the supernatant. Add distilled water to the original volume, stir the solution to suspend the nickel powder, stand again to make the nickel powder sink, and pour off the supernatant. Then transfer to a 2l beaker, pour off the supernatant, add 500ml of an aqueous solution containing 50g of sodium hydroxide, stir, place, and pour off the supernatant. Add 500ml of distilled water, stir, place, and pour off the supernatant. Repeat this water washing several times until the eluate is neutral to the litmus paper, and then wash 10 times (about 20-40 times). Pour off the supernatant, add 200ml of 95% ethanol, wash three times with decantation, and then wash three times with absolute ethanol. The prepared Raney Ni catalyst should be stored in a ground bottle containing absolute ethanol (not in contact with air), the catalyst must be stored below the liquid surface, and the Raney Ni suspended in the liquid weighs about 150g.

[0028] Example 3 Hydrodehalogenation of different halogenated phenolic compounds

[0029] Weigh 25mg of the Pd/C catalyst prepared in Example 1 and add it to a 100ml three-necked flask, add 80ml of 4-CP aqueous solution with a concentration of 5000ppm, and make the reactant be adsorbed for 15min under stirring with a magnetic stirrer; then pass N 2 , Do this three times, then pass H 2 , H 2 The flow rate is controlled within the range of 10-30ml/min, and the alkali used is sodium hydroxide. In order to ensure that the second step oxidation reaction can proceed relatively quickly, the molar ratio of the amount of alkali to the amount of the reaction substrate is 1.1:1. The reaction temperature was controlled at 30°C, and the reaction pressure was normal pressure. The specific dechlorination results are shown in Table 2.

[0030] Table 2 Hydrodehalogenation of different halogenated phenol compounds

[0031]

[0032] Remarks: CP means monochlorophenol, BP means monobromophenol, DCP means dichlorophenol, TCP means trichlorophenol, PCP means pentachlorophenol.