Catalytic Wet Air Oxidation Of Coking Wastewater

Phenol and quinoline are the main pollutants in coking waster. According to the mass ratio of the two pollutants, the simulated coke-plant wastewater was prepared. Iron (Fe), the transition metal, as the active component of the catalyst; the activated carbon (AC) and montmorillonite (MMT) as the supporter. In other words the Fe/AC and Fe-Al-MMT catalyst were prepared respectively. According to the characterized and experimental results the preparing process of the catalysts have been taken.The catalysts were used for simulated coke-plant wastewater by the CWPO treatment, under the different process, the stability of the catalyst. When under different process of the coke-plant waster the TOC or COD removal as the evaluation. The coke-plant waster was treated by CWPO process the conditions on COD and TOC removal.Activated carbon-supported Fe catalysts (Fe/AC) have been prepared by incipient impregnation and was characterized by means of BET and TG analysis. Phenol, quinoline, the main pollutants in coking waster, have been treated by CWPO. The preparation of Fe/AC catalyst and the process of CWPO has been studied. The results showed:the loading of Fe, the calcination temperature, the initial pH and the dose of the oxidant(H2O2) have greatly influenced the catalyst's stability and the catalytic activity. The Fe loading of the catalyst is 2%, the catalyst was calcinated at 300℃for 4h, when the initial pH is 5, the reaction temperature is 60℃; the dose of the hydrogen peroxide is 2100mg/L, the dose of catalyst used 10g/L meanwhile Fe leaching is 5.79mg/L.Clay pillared with Fe-Al was made as a catalyst for CWPO (catalytic wet peroxide oxidation) of simulated coke-plant wastewater (phenol, quinoline). The Fe-Al pillared (Fe-Al-MMT) clays was characterized by BET surface, X-ray diffraction (XRD), thermal gravimetric (TG) and differential scanning calorimetry (DSC), the results shows:the thermal stability of the pillared clays is stronger than the shopping sodium montmorillonite due to the interaction between the iron species and the catalyst support. Then, the catalyst's performance in CWPO was analyzed under different operating conditions such as the reaction temperature, initial pH and H2O2 dose.Fe-Al-MMT catalyst was reused under considerable operating conditions (reaction temperature is 60℃, pH initial=3, [H2O2]0=2100mg/L, Wcat= 5g/L), the solids shows high stability in the reaction due to strong interaction between the iron species and the catalyst support. The pillared clays were also stable against the leaching out of Fe.H2O2 decomposition kinetics of two different catalysts were studied. Fe/AC catalyst was used at the best processing conditions the reaction order of H2O2 decomposition is 1.14, the activation energy Ea=67.46kJ/mol, however, when the Fe-Al-MMT catalyst was used under the best processing conditions the reaction order of H2O2 decomposition is 1.39, meanwhile the activated energy Ea=80.57kJ/mol.This study also compare the Fe/AC catalyst and Fe-Al-MMT catalyst on preparation method, preparation cycle, Fe leaching, the lives of the catalyst and so on. The Fe/AC catalyst preparation method is easy and simple, also the preparation period is short. However, the iron on the catalysts leaching is large, the catalyst's stability is not stable enough, the dosage is more large than the Fe-Al-MMT catalyst. Generally speaking, Fe-Al-MMT catalyst is better the Fe/AC catalyst on CWPO as the catalyst.