Cu-SSZ-39　has　garnered　significant　attention　because　of　its　outstanding　NH3-SCR　activity　and　hydrothermal　stability.　To　facilitate　commercial　application　of　Cu-SSZ-39,　it　is　crucial　to　streamline　the　synthesis　process,　adopt　eco-friendly　synthesis　methods,　enhance　the　catalytic　performance,　and　explore　the　underlying　catalytic　mechanisms.　Herein,　ammonia　exchange　was　skipped　and　Cu-SSZ-39　was　directly　synthesized　via　Cu-exchange　of　Na-SSZ-39.　This　approach　yielded　a　Cu-SSZ-39　with　superior　catalytic　performance　compared　to　that　prepared　using　the　conventional　NH4-SSZ-39.　Comparative　characterization　of　the　Cu-SSZ-39　catalysts,　derived　from　both　Na-SSZ-39　and　NH4-SSZ-39　exchanges　demonstrated　that　the　positioning　of　Na　cations　affected　Cu　distribution,　and　controlling　Na　distribution　can　enhance　deNOx　activity.　It　was　also　found　that　while　cation　locations　did　not　alter　the　reaction　mechanism　of　Cu-SSZ-39　at　low　temperature,　they　did　increase　the　concentration　of　active　NOx　intermediates,　thereby　boosting　catalytic　performance.　This　study　facilitates　a　more　sustainable　synthesis　of　Cu-SSZ-39　and　provides　deeper　insights　into　how　cations’　distribution　in　zeolites　affects　catalytic　efficiency.　©　2025　Elsevier　Inc.