AsH₃ Removal By Copper Modified Activated Carbon At Low Temperature And Regeneration Studies

AsH₃ is a global toxic pollutant because of high toxicity.And because it’s easy to poison the catalyst,the removal efficiency of the catalyst to other gases will be significantly lowered,the working life of the catalyst is greatly cut down,and the cost of waste gas purification is increased.It is major to find a new way for the valid removal of AsH₃ from industrial waste gas,which is of great necessary in the fields of environmental protction and industrial links.Based on the research status of AsH₃ removal and comprehensive benefits in industrial application,the study on AsH₃ removal and regeneration at low temperature was carried out in this paper.This paper studied the Cu was impregnated activated carbon for AsH₃ removal effect and its mechanism,The three preparation factors influencing Cu impregnation precursors,Cu loading capacity and drying temperature,two reaction factors influencing oxygen content and reaction temperature were investigated.In order to study the removal efficiency of AsH₃,a series of Cu-modified catalysts were prepared by impregnation method.The best preparation conditions of Cu/C catalyst were determined:The catalyst was impregnated with 2 mol/L Cu（NO₃）₂ precursor of copper nitrate and then dried at 180℃ for 4 h.When the oxygen content is 1%and the reaction temperature is 40℃,in 42 h reaction time,the Cu/C catalyst maintains over90%removal efficiency for AsH₃.The adsorption capacity reached 369 mg/mg.By specific surface area（N₂-BET）,X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,acid sites（NH₃-DRIFTS）,In Situ infrared analysis（In Situ DRIFTS）,Fourier transform infrared spectroscopy（FT-IR）,thermogravimetric analysis（TG）and the regeneration experiment,the physicochemical properties,phase element of the catalysts,thermostability and catalytic nature were stutyed,revealing the Cu/C catalyst for catalytic removal mechanism of AsH₃.The results showed the importance of conversion cycle of Cu²⁺and Cu⁺in the removal of AsH₃ over Cu/C catalyst,and the presence of intermediate Cu₂（NO₃）（OH）₃ in the decomposition process of Cu（NO₃）₂ into CuO was also the cause for the good regeneration performance of Cu/C catalyst using water washing and gas regeneration method.The B-acid site of Cu/C catalyst could quickly improve the chemisorption of oxygen,thus increasing the catalytic reaction with AsH₃ at the B-acid site.The AsH₃ in the gas phase was captured by Cu/C and catalyzed to As₂O₃ at first,which was solidified on the surface of the catalyst and further catalyzed to As₂O₅.A new idea could be offered to simplifying the making ways and lower the operating cost of removing AsH₃.It was proved that Cu/C was a catalyst for achieving high removal rate of AsH₃ and had the prospect of large-scale industrial application.