Efficient Preparation And Characterization Of Cu-SAPO-34 Catalyst

In recent years,due to the rapid improvement of economy and the vigorous development of transportation industry and the extensive use of fossil fuels,the global air pollution is serious.Among them,nitrogen oxide（NO_X）has become a major pollution source of the air environment,and it is difficult to solve.The existence of NO_Xdoes great harm to the environment and human beings.NO_Xwill cause acid rain and destruction of the ozone layer.It will also combine with heme in human blood and do harm to people’s health.In the current NO_Xtreatment methods,NH₃-SCR reaction has attracted the attention of scholars because of its excellent denitration ability,and the most important role of NH₃-SCR reaction is the activity of catalyst.At present,metal based molecular sieves have excellent performance in NH₃-SCR reaction（such as Cu,Fe）,mainly including Cu-SSZ-13,Cu-SAPO-34,Cu-ZSM-5,Fe-Beta molecular sieves,etc.Among them,Cu based SSZ-13 and SAPO-34 zeolite with CHA topology have the advantages of excellent NH₃-SCR activity,wide temperature window range and environmental friendliness.However,the expensive template used in the synthesis process,complex preparation process and serious environmental pollution make the synthesis cost of the catalyst high and the reaction activity will be limited.In order to solve the above problems,this paper has done the following work.（1）SAPO-34 was prepared using different templates and Al PO₄as phosphorus source and aluminum source.Cu ion exchange was carried out on this series of catalysts,and Cu/SAPO-34catalyst was successfully prepared.The Cu/SAPO-34 catalyst was characterized and its activity was evaluated.The NH₃-SCR activity of the prepared catalyst was compared with that of Cu/SAPO-34 catalyst prepared by traditional phosphoric acid as phosphorus source.Through comparison,it is found that Cu/SAPO-34 prepared by Al PO₄has wider temperature window range and higher NO conversion than conventional Cu/SAPO-34.（2）Based on the synthesis of SAPO-34 catalyst,the Cu-SAPO-34 catalyst with various Cu content was successfully prepared by using different template.The catalyst was characterized by NH₃-TPD,XRD,H₂-TPR and XPS,and then the activity was tested.The test results show that the Cu-SAPO-34 catalysts with different Cu content prepared by these templates have excellent catalytic activity.The NO conversion rate of several samples can reach 80%in the range of150-400℃,among which with diethylamine and TEPA were used at the same time.The NO conversion of Cu_0.05-SAPO-34 catalyst is about 100%.In addition,in the range of temperature window,the concentration of by-product N₂O is lower than 20 ppm,and the yield of by-product is low.（3）Through the summary of the above experiments,it is proposed to use TEPA as template and copper ion complexing agent at the same time,Cu-SAPO-34 catalyst uses Al PO₄as phosphorus source and aluminum source,and is prepared in one-pot under the conditions of different copper content.The Cu-SAPO-34 catalyst was fully characterized by XRD,SEM,NH₃-TPD,UV-Vis and XPS.Compared with the Con-Cu-SAPO-34 catalyst,the NH₃-SCR activity test shows that the catalyst synthesized with different Cu content has different activity.