Research On Low Temperature Desulfurization And Denitration Catalysts Promoted By Graphene

In recent years,in response to the air pollution caused by coal-fired power plants,the state has formulated a series of air pollutant emission standards,and put forward strict requirements for the control technology of air pollutant emissions from coal-fired power plants.In the past few decades,facing the increasingly serious air pollution situation,various countries have taken certain control measures.Most coal-fired power plants are equipped with dedusting,desulfurization,and denitration staged treatment devices.This process has the advantages of strong selectivity and relatively stable treatment of pollutants,but the overall structure of the treatment system is complex and covers a large area.In addition,the high operating temperature（300-420°C）of commercial catalysts in the traditional thermal power industry leads to increased operation and maintenance costs and waste of a large amount of reaction heat,which is not suitable for the popular application of small and medium-sized power plants.Therefore,the development of new technologies for simultaneous removal of pollutants such as SO₂and NOx at low temperature is another important breakthrough in the field of flue gas purification.In this study,by the method of impregnation synthesis,ZSM-5 molecular sieve was used as the carrier,V and Cu were used as active components,Ce was used as a promoter,and graphene oxide（GO）was incorporated.The removal efficiency and influencing factors of SO₂and NO;BET,SEM,XRD and XPS characterizations were carried out to study the internal structure of the catalyst,which provided a new method for the simultaneous removal of multiple pollutants in coal-fired flue gas at low temperature.The experimental results show that the desulfurization catalyst has the best SO₂removal efficiency when the calcination temperature is 550℃,the loading of active component vanadium is 7%,and the loading of cerium as promoter is 7%,and the removal rate is 88.83%.%;the denitration catalyst has the best NO removal efficiency when the calcination temperature is 550℃,the loading of active component copper is 8%,and the loading of cerium as auxiliary agent is 7%,and the removal rate is 75.31%.Graphene promotion experiments were carried out on the two catalysts.The results showed that when the incorporation ratio of graphene was 0.5%,the removal efficiencies of SO₂and NO were improved,reaching 92.15%and 79.74%,respectively.On the basis of the single desulfurization experiment and denitration experiment,the experiment of simultaneous desulfurization and denitration of the catalyst was also carried out.The experimental results show that the V（7%）-Cu（8%）-Ce（7%）-ZSM-5 catalyst prepared by the sequential impregnation method has the best performance when the calcination temperature is 550°C,due to V and Cu.There is a certain synergy.At the reaction temperature of 150°C,the removal efficiencies of SO₂and NO are 90.22%and 78.35%,respectively,and the efficiencies of desulfurization and denitrification are higher than those of single removal.The graphene promotion experiment was carried out on the simultaneous desulfurization and denitration catalyst.The results showed that when the incorporation ratio of graphene was 0.5%,the removal efficiency of SO₂and NO reached the maximum,reaching 94.60%and 83.64%,respectively.The BET characterization results show that when the three elements of V,Cu,and Ce are loaded,the pore structure of the original support is improved.When graphene is added,the support is further improved,thereby improving the catalytic effect of the catalyst.SEM and EDS characterization results showed that there was agglomeration on the surface of the catalyst,and substances in several particle states were uniformly dispersed on the surface of the catalyst carrier,indicating that during the catalyst synthesis process,the ZSM-5 carrier could stably immobilize V,Cu,Ce and other important components.When GO was incorporated,the particle fraction on the surface of the support was more uniform,which increased the number of catalytic active sites,which was beneficial to improve the catalytic efficiency of the catalyst.The XRD characterization results show that the diffraction peaks of V,Cu,Ce elements all appear,indicating that there is a chemical interaction between V,Cu,Ce and other elements and the ZSM-5 support,and they are fixed on the ZSM-5 support.With the addition,the position of the characteristic peak of the spectrum does not change,but the intensity increases and the loading of the element increases.