Commercial SAPO-11 and SAPO-34 were obtained from Fushun Catalyst Factory and Dalian Institute of Chemical Physics, respectively. The final composition was (Si2.54Al19.4P18.1)O80 for SAPO-11 and (Si5.68Al33.48P27.28)O130 for SAPO-34. Hydrothermal method is described as the following steps. SAPO powder was diluted in water and mixed well with zinc nitrate or manganese nitrate solution of different concentration at room temperature. The mixture was stirred for 2 h, and then transferred to stainless steel reactor with Teflon-lined to crystallization for 2 h at 150 8C. The product was filtrated, washed, and dried at 120 8C for 2 h, followed by calcining at 600 8C for 4 h. Impregnation method was almost the same as above without the crystallization step.