Study On CuO/ACNT Catalyst For Catalytic Oxidation Of Arsine Under Low-temperature And Micro-oxygen Conditions

China is a major producer of yellow phosphorus.In the production process of phosphorus,a large amount of yellow phosphorus exhaust gas is generated.The yellow phosphorus tail gas contains a large amount of carbon monoxide（CO）,which is an important raw material for carbon-chemical industry.If CO in yellow phosphorus tail gas can be recovered well,the yellow phosphorus tail gas can be effectively utilized.However,the presence of toxic and harmful gases in the yellow phosphorus tail gas CO is difficult to effectively use.In order to remove arsenic hydride（AsH₃）from yellow phosphorus tail gas,we selected multi-wall carbon nanotubes（MWCNTs）as the carrier and prepared catalysts for the removal of AsH₃ by ultrasonic impregnation method.The following three aspects were studied:Study on the effect of acid steam pretreatment and preparation conditions on AsH₃ removal performance of catalyst;Study on the effect of reaction conditions on the performance of CuO/ACNT catalysts on removal of AsH₃;Study on surface reaction mechanism of CuO/ACNT catalysts and CuO/ACNT catalysts regeneration.The effect of acid steam pretreatment and preparation conditions on AsH₃ removal performance of catalyst:the MWCNTs before（PCNT）and after（ACNT）the acid steam treatment were selected as the carrier,and different metal salts were selected as the impregnation liquid to prepare a series of catalysts.The results showed that the catalyst showed the best AsH₃ removal when the impregnated liquid was copper salt.By comparison,it was found that the acid steam treatment could significantly improve the ability of the catalyst to remove AsH₃.Taking the catalyst with copper salt as the impregnating liquid as an example,When the carrier is ACNT,the catalyst can be maintained for 150 min without deactivation,and when the carrier is PCNT,the catalyst will be deactivated within 30 min.TPCNT,ACNT and copper-based catalystwere characterized,and the results showed that acid treatment could greatly increase the specific surface area and pore volume of the carrier,enrich the functional groups on the catalyst surface,and increase the content of copper on the catalyst surface.This paper mainly screened the copper salt precursor,loading and calcination temperature.The results showed when the copper salt precursor was copper nitrate（Cu（NO₃）₂）,The mass ratio of copper oxide（CuO）to multi-walled carbon nanotubes was 15%,and the calcination temperature was 300℃,the catalyst showed the best removal effect on AsH₃.It can efficiently remove AsH₃ within 2640 min without inactivation,and the penetration arsenic capacity can reach 1069 mg/g.Through analysis,it is found that the precursor,loading and calcination temperature mainly affect the catalytic oxidation performance of the catalyst by affecting the form of surface components on the catalyst and the specific surface area of the catalyst.The effect of reaction conditions on the performance of CuO/ACNT catalysts on removal of AsH₃:The effects of oxygen content,inlet concentration,reaction temperature and gas hourly space velocity on AsH₃ removal performance of catalyst were mainly investigated.When the oxygen content was 0.9%,the reaction temperature is 140℃,the inlet concentration was 100 ppm,and gas hourly space velocity was20000 h^-1,The 100%removal time of AsH₃ can reach 4680 min.Through characterization,the reaction product is most likely to be Arsenic trioxide（As₂O₃）,and the type of the reaction product does not change with the change of oxygen content and reaction temperature.Surface reaction mechanism of CuO/ACNT catalysts and CuO/ACNT catalysts regeneration:According to the characterization results,It was further determined that the reaction product was As₂O₃,the reaction mechanism on the catalyst surface was preliminarily proposed.The removal process of AsH₃ on the catalyst surface is mainly carried out in three stages.The first stage is the physical adsorption stage,AsH₃ is adsorbed on the catalyst surface or the inner wall of the pore to be removed;The second stage is the catalytic oxidation process,O_βprior to the chemical reaction with AsH₃ on the catalyst surface to generate As₂O₃ and H₂O.CuO plays two main roles at this stage:On the one hand,the O_αin CuO can be converted into O_βand participate in the oxidation of AsH₃;On the other hand,CuO can promote the conversion of oxygen in the air into O_βand provide sufficient"oxidant"for the oxidation of AsH₃.During the reaction,copper oxide and cuprous oxide will be converted to each other and eventually reach a chemical equilibrium state;The third stage is the deactivation stage,During the reaction,AsH₃ will be converted into As₂O₃.Increasing As₂O₃ would cover the surface of the catalyst,eventually affecting the total area of copper oxide exposed to the gas atmosphere,thus reducing the activity of the catalyst to AsH₃.In addition,the regeneration results showed that the arsenic capacity of the catalyst after two regeneration could still reach 94.8%of the fresh sample.