The Study On Cu-SSZ-13 Applied To Wide Temperature Denitration Catalyst

Nitrogen oxide is one of the most important pollutants in flue gas emissions from coal-fired power plants.Ammonia selective catalytic reduction technology is currently the most effective and widely used method for removing NOx,and the key technology is the development of catalysts.Cu-based small pore size Cu-SSZ-13 molecular sieve catalyst with CHA crystal configuration has attracted extensive attention due to its excellent low temperature denitration activity,wide high activity window and excellent hydrothermal stability.In this paper,Cu-SSZ-13 was synthesized in one step by hydrothermal method and its related properties were studied.In this paper,Cu-SSZ-13 was synthesized in one step by hydrothermal method using inexpensive copper amine complex as copper source and templating agent,and then ion exchange was carried out with 1 mol/L NH4Cl solution,and then,the ion-exchanged catalyst is subjected to a modification of Ce of 0.01%to 1%by the ultrasonic impregnation method.So we got Cu-SSZ-13 raw powder and two modified catalysts at last.The physicochemical properties were characterized by XRD,SEM,BET,XRF,XPS,NH3-TPD/H2-TPR,XRF and XPS methods,and denitration evaluation was carried out under simulated flue gas environment.The main results are as follows.The sequential experimental method was used to investigate the effects of initial gel Cu-TEPA dosage,silicon-aluminum ratio and Cu dosage on the catalytic denitrification activity,catalyst stability and physicochemical properties of the synthesized catalyst.A relatively good initial gel material configuration was determined:Al2O3:SiO2:Cu-TEPA:Na2O:H2O= 1:10:1.75:4:300.The Cu-SSZ-13 synthesized under this scheme has a specific surface area of about 340 m2/g,a CuO loading of about 10%,and a denitration rate of 90%or more in the range of 200-450℃.The results of ion exchange treatment of 1mol/L NH4Cl solution on the catalyst showed that the ammonium exchange can effectively improve the dispersion state of the active central copper species in the catalyst and elute the impurity Na+.After the ammonium exchange,the temperature range was widened to 190-475℃,where the denitration rate of the catalyst was above 90%,and even reached 100%in the range of 250-350℃.After passing through a reaction gas containing 100 ppm of SO2 at 250℃ for 160min,it still has a denitration performance higher than 70%,while the non-ammonium exchange sample reacts for 20 min,and the denitration rate is lowered to 45%.So the sulfur resistance performance is improved remarkably.The loading modification experiment of cerium on Cu-SSZ-13 catalyst showed that the modified catalyst still had more than 80%denitration performance after being introduced into the reaction gas containing 100ppm SO2 at 250℃ for 160min,and compared with the unmodified catalyst,the denitration activity has a 5-10%increase.