固定床中γ-Al2O3负载金属氧化物催化臭氧氧化研究

Study of catalytic ozonation by metal oxides supported on γ-Al2O3 in fixed-bed reactor

非均相催化臭氧氧化技术是一种高效的废水处理技术,但目前非均相臭氧催化剂主要为粉体形态,常用于静态或半连续态反应器中,其于固定床中的催化性能并不明确.设计了连续态固定床反应体系,以γ-Al2O3颗粒为载体,Mn、Fe、Ce的氧化物为活性组分制备负载型催化剂,并以对硝基苯酚(PNP)为目标污染物,探究其在不同工艺条件下的催化性能.实验结果表明,负载CeO2的催化剂催化效果最好;化学需氧量(COD)和总有机碳(TOC)的去除率随着活性组分CeO2负载量、水力停留时间(HRT)、O3浓度的增加而增加;当CeO2负载量为12.3%、HRT为15 min、O3浓度为16.2mg/L时,6h COD和TOC平均去除率分别达到86.3%和91.7%;此外,该体系在pH为5.0~9.0均表现出良好催化性能,并具有良好的长时间运行能力.

Heterogeneous catalytic ozonation is an efficient technology in water treatment.However,most of the researches are focused on powder catalysts and operated in static or semi-continuous reactors,which are impractical in real application.Herein,continuous fixed-bed reaction system withγ-Al2O3 pellets as carrier and Mn/Fe/Ce oxide as active components is designed.Its catalytic performance is determined in different conditions with p-nitrophenol as a model pollutant.Results show that among the three supported catalysts andγ-Al2O3 carrier,CeO2/γ-Al2O3 shows the best catalytic performance.Chemical oxygen demand(COD)and total organic carbon(TOC)removal efficiencies are increased with the increase of CeO2 loading content,hydraulic retention time(HRT)or O3 concentration.With CeO2 loading content of 12.3%,HRT of 15 min and O3 concentration of 16.2 mg/L,the COD and TOC average removal efficiency in 6 h reaches to 86.3%and 91.7%,respectively.Moreover,the catalyst shows good catalytic performance under a wide pH range of 5.0-9.0 and the catalytic performance of this system remains stable during a long running time.