MOLECULAR SIEVE AND ITS PREPARATION METHOD

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The present invention discloses a molecular sieve and its preparation method. The molecular sieve has micromorphology in a football shape and consists of molecular sieve framework and active elements. The molecular sieve framework comprises silicon element and aluminum element; the active elements comprise copper element and rare earth elements. The rare earth elements are one or more selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Sc and Y. The mass ratio of the silicon element to the aluminum element is 3-9 : 1. The content of the copper element in the molecular sieve is 1.5-3.2 wt%. The mass of rare earth elements is 50 ppm-2 wt% of the molecular sieve framework. The mass of the silicon element is calculated by silicon dioxide, the mass of aluminum element is calculated by aluminum oxide, the mass of copper element is calculated by copper oxides, and the mass of rare earth elements is calculated by rare earth oxides. The molecular sieve has a high catalytic activity in a temperature range of 175-550 °C and a good resistance to hydrothermal aging.