In this research, the Mn–Ni–Co doped APSO-34 nanostructured materials were studied in the C3H8-assisted reduction of NOx. The MeAPSO-34 samples were prepared via ultrasound-assisted hydrothermal design upon the isomorphous substitution of transition metal ions into the crystalline lattice. Several characterization techniques such as XRD, FESEM, EDX dot-mapping, BET-BJH, FTIR and TPD-NH3 were used for study the properties of the catalysts. The XRD patterns indicated that the rate of nucleation and crystal growth were different for incorporating the various dopant ions in the CHA framework. The entrance of Mn and Co into the silicoaluminophosphate framework led to the formation of small particles with uniform distribution. Based on the acidity results, the MnCoAPSO-34 molecular sieve favored the increase in the density and strength of acid sites. Furthermore, it was found that the strength and density of acid sites may have a clear effect on catalytic NOx reduction. Therefore, the MnCoAPSO-34 zeolite showed the maximum conversion of NOx to N2 (76%) at reaction temperature of 450°C. Moreover, the mechanism of MeAPSO34 synthesis and also a set of reaction stages for propane-assisted NOx reduction based on the obtained data were presented.
