Cu-SSZ-13(CHA topology)zeolites are commonly used in diesel engines for the selective catalytic reduction(NH3-SCR)of nitrogen oxides(NO_(x)).However,their synthesis typically requires long crystallization times and th...Cu-SSZ-13(CHA topology)zeolites are commonly used in diesel engines for the selective catalytic reduction(NH3-SCR)of nitrogen oxides(NO_(x)).However,their synthesis typically requires long crystallization times and their durability in NH3-SCR is limited.Herein,we achieved a significant reduction in crystallization time,synthesizing SSZ-13 zeolites in just 6 h by using SAPO-18 seeds and a minimal amount of an organic structure-directing agent(OSDA).The OSDA/Si ratio was reduced by a factor of 16 compared to conventional methods.Crystallization studies revealed that SAPO-18 seeds promoted the formation of four-membered rings(4MRs),which quickly combined into double 6-membered rings(D6Rs)with the assistance of the OSDA,enabling rapid crystallization of SSZ-13.The resulting Cu-SSZ-13 demonstrated comparable NH3-SCR performance to conventionally synthesized Cu-SSZ-13(Cuconv-SSZ-13).Moreover,we introduced Ce ions into Cu-SSZ-13 to enhance its hydrothermal stability and explored the effects of different metal precursors on the catalytic performance.The optimized CuCe(Ⅲ)0.5-SSZ-13 exhibited superior hydrothermal stability compared to Cu-SSZ-13.Conversely,CuCe(Ⅳ)1.0-SSZ-13 and CuCe(Ⅲ)0.5Ce(Ⅳ)1.0-SSZ-13 displayed reduced hydrothermal stability.Characterization revealed that using the Ce(Ⅲ)precursor inhibited CuO_(x) formation during hydrothermal ageing,while the Ce(Ⅳ)precursor favored the formation of CeO2,decreasing the zeolite stability and promoting CuO_(x) formation.This work presents a novel approach for rapid SSZ-13 synthesis and highlights the critical role of metal precursors in the performance of bimetallic SSZ-13 zeolites.展开更多
基金the National Natural Science Foundation of China(22301209,22476147,22288101,22405293)the Zhejiang Province Science Technology Planning Project(no.2021C03023)+1 种基金the Zhejiang Provincial Natural Science Foundation of China(no.ZCLQ24B0101)the‘111 Center’(B17020)for supporting this work.
文摘Cu-SSZ-13(CHA topology)zeolites are commonly used in diesel engines for the selective catalytic reduction(NH3-SCR)of nitrogen oxides(NO_(x)).However,their synthesis typically requires long crystallization times and their durability in NH3-SCR is limited.Herein,we achieved a significant reduction in crystallization time,synthesizing SSZ-13 zeolites in just 6 h by using SAPO-18 seeds and a minimal amount of an organic structure-directing agent(OSDA).The OSDA/Si ratio was reduced by a factor of 16 compared to conventional methods.Crystallization studies revealed that SAPO-18 seeds promoted the formation of four-membered rings(4MRs),which quickly combined into double 6-membered rings(D6Rs)with the assistance of the OSDA,enabling rapid crystallization of SSZ-13.The resulting Cu-SSZ-13 demonstrated comparable NH3-SCR performance to conventionally synthesized Cu-SSZ-13(Cuconv-SSZ-13).Moreover,we introduced Ce ions into Cu-SSZ-13 to enhance its hydrothermal stability and explored the effects of different metal precursors on the catalytic performance.The optimized CuCe(Ⅲ)0.5-SSZ-13 exhibited superior hydrothermal stability compared to Cu-SSZ-13.Conversely,CuCe(Ⅳ)1.0-SSZ-13 and CuCe(Ⅲ)0.5Ce(Ⅳ)1.0-SSZ-13 displayed reduced hydrothermal stability.Characterization revealed that using the Ce(Ⅲ)precursor inhibited CuO_(x) formation during hydrothermal ageing,while the Ce(Ⅳ)precursor favored the formation of CeO2,decreasing the zeolite stability and promoting CuO_(x) formation.This work presents a novel approach for rapid SSZ-13 synthesis and highlights the critical role of metal precursors in the performance of bimetallic SSZ-13 zeolites.
