The desorption peaks at low and high temperature corresponded to the weak and moderately strong acid sites in the molecular sieve framework, respectively. The acid amounts corresponding to the amounts of adsorbed NH3 were estimated from the areas underlying the NH3-TPD curves. The relative distribution of these two types of acid sites 1:3, suggesting the presence of a substantial amount of moderately strong acid sites in the Mn-SAPO-34 or Zn- SAPO-34.