Sulfur Poisoning Of CuO-CeO₂ Catalyst In CO Oxidation At Low Temperatures

CuO-CeO₂ catalyst is a common and efficient catalyst for the oxidation of CO,and has been widely studied because of its abundant resources and low price.However,when the catalyst was reacting in sulfur-containing atmosphere,the activity of the catalyst decreased significantly or even directly deactivated,and the deactivation was irreversible.In this paper,the sulfur poisoning phenomenon of CuO-CeO₂ catalyst prepared by different methods and the methods to improve its sulfur resistance were studied.The main contents are as follows:（1）The solvothermal method（SM）,impregnation method（IM）and coprecipitation method（CP）were used to prepare CuO-CeO₂ catalyst,and the differences of sulfur poisoning phenomena of CuO-CeO₂ catalyst prepared by different methods in CO oxidation reaction were investigated.The results showed that the sulfur resistance was SM>CP>IM.The texture of the catalyst changed after sulfur poisoning,and the content of Cu⁺,Ce³⁺and surface adsorbed oxygen increased,which was due to the formation of copper sulfate and cerous sulfate（Ⅲ）.Cerous sulfate（Ⅳ）was also produced after sulfur poisoning of SM and IM catalysts by SO₂-TPD characterization.The sulfur resistance of catalysts prepared by different methods varies greatly,which may be due to the differences in the catalysts themselves caused by different preparation methods,and the types and amounts of sulfates generated after sulfur poisoning are different.（2）CuO-CeO₂ catalyst was prepared by solvothermal method,and the catalyst was reacted in three different atmospheres to investigate the phenomenon of CuO-CeO₂ catalyst sulfur poisoning and the influence of water vapor introduction on its sulfur resistance.The results showed that the activity of the catalyst was basically unchanged in CO mixture for 16 h,and the activity of the catalyst gradually decreased to complete inactivation after SO₂ was introduced.At the same time,the catalyst was rapidly inactivated to the CO conversion rate of32%in the first hour after SO₂ and water vapor was introduced,and then the activity gradually decreased to complete inactivation.The texture of the catalyst changes after sulfur poisoning,which is due to the formation of metal sulfate.At the same time,the content of Cu⁺,Ce³⁺and adsorbed oxygen on the surface of SO₂ and water vapor catalyst after sulfur poisoning was greater,and the formation rate of sulfur species was faster,indicating that the presence of H₂O accelerated the formation of metal sulfate.（3）CuO-CeO₂ catalyst was prepared by impregnation method,and different contents of surfactant PEG600 were added to assist impregnation in the preparation process,to explore whether the addition of PEG600 is conducive to improving the anti-sulfur performance of the catalyst,and what effect the added content has on the anti-sulfur performance.It was found that the sulfur resistance of the catalyst with PEG600 dosage of 0.1g was improved,because the catalyst has more Cu⁺,Ce³⁺species and oxygen vacancy,the CuO grain size is the smallest,the specific surface area is the largest,CuO is highly dispersed and more active sites,the oxygen species on the surface is more prone to CO reaction,reducing the competitive adsorption of SO₂.