Background Selective catalytic reduction of nitrogen oxides with ammonia (NH3-SCR) is an effective method for the nitrogen oxides (NOx) removal. This study aimed to develop a highly efficient NH3-SCR catalyst using the naturally available Montmonrillonite (Mt) clay as the catalyst support. Results Mt was processed into PILC by Al/Zr intercalations, impregnated with MnCe mixed active components and loaded with transition metals to achieve X-AlZr-PILC-MnCe (X = V, W, Co or Mo) catalysts. The optimized Mo-AlZr-PILC-MnCe showed the best NH3-SCR performance with a NO conversion rate of nearly 100% in the temperature range of 240-300 degrees C, and N-2 selectivity of above 85% in the range of 140-300 degrees C. Conclusions The catalysts were characterized by SEM, BET, XRD, XPS, H-2-TPR, NH3-TPD to define the relationships between structure, chemical properties and catalytic activity. The enhanced catalytic performance of Mo-AlZr-PILC-MnCe was mainly owing to the increased acidity and better redox ability. In situ DRIFT studies indicated the deposition of Mo changed the reaction from the E-R to the L-H mechanism. (c) 2020 Society of Chemical Industry