One-step Synthesis Of Highly Reactive Cu-SAPO-34 And Its NH₃-SCR Properties

The continuous progress of science and technology will inevitably cause a lot of environmental problems,among which the large amount of nitrogen oxides emitted by diesel vehicle exhaust has posed a great threat to the ecological and social environment.At present,the most effective technology to control nitrogen oxides is NH₃ selective catalytic reduction(NH₃-SCR),so the development of an efficient SCR catalyst has become a hot topic of current research.Molecular sieve catalysts have been widely used in the field of SCR due to their unique shape selection,good low temperature catalytic activity and excellent stability.In this paper,Cu-SAPO-34 catalyst with excellent denitrification performance was prepared by hydrothermal method in one-pot procedure,in which Triethylamine(TEA)was used as template,a new complexing agent Tetraethylenepentamine(TEPA)was introduced,in the meaning while,the influence of different Cu content and different Cu source on catalytic performance was further analyzed.1.Series of Cu-SAPO-34 catalysts were synthesized by one-pot method with or without addition of TEPA,and the effects of TEPA introduction on various physical and chemical properties of Cu-SAPO-34 catalyst were also studied.It was found that the catalytic activity was greatly improved after adding TEPA in the precursor due to more active centers and more acid content formation in the catalyst.At the same time,it was also found that the addition of TEPA can inhibit the formation of Cu O,ensuring the catalyst has a good low temperature activity.2.A series of catalysts with different Cu loading were obstained by one-step method,in which TEPA was added in the initial synthesis gel.The results showed that 0.15-Cu-SAPO-34 catalyst had the widest operating temperature window,and could achieve more than 90%NO_x conversion in the temperature range of 150-500 ^oC.The results of H₂-TPR and NH₃-TPD confirmed that the moderate acid content and redox ability guaranteed the good catalytic activity of the compound.3.After determining the most suitable Cu load,the influence of different Cu source on the catalytic performance was explored.²⁹Si NMR and XPS results showed that the Cu-SAPO-34-TC catalyst with cu-citrate as the source had better skeleton stability and more isolated Cu²⁺species on the catalyst surface.A series of stability tests showed that Cu-SAPO-34-TC had excellent resistance to H₂O/SO₂,hydrothermal stability and high space speed.