Rapid and efficient synthesis of CHA-type zeolite by interzeolite conversion of LTA-type zeolite in the presence of N, N, N-trimethyladamantammonium hydroxide

Abstract

SSZ-13 zeolite with CHA structure has been synthesized rapidly and efficiently via interzeolite conversion of LTA zeolite in the presence of N, N, N-trimethyladamantammonium hydroxide (TMAdaOH) under hydrothermal conditions. Crystallization processes of LTA-CHA interzeolite conversion at different temperatures were investigated in detail by XRD, SEM, FT-IR, etc. The results show that the use of LTA zeolite greatly increases the crystallization rate of CHA zeolite due to the generation of locally ordered aluminosilicate species via the dissolution of LTA zeolite. The crystallization time of SSZ-13 zeolite is shortened to 5 h at 180 ℃. Moreover, the calcined SSZ-13 zeolite possesses high crystallinity, uniform spherical morphology and high surface area. In addition, catalytic test in the selective catalytic reduction of NOx with NH3 (NH3-SCR) shows that copper exchanged CHA (Cu-SSZ-13) exhibits comparable catalytic properties to those of Cu-SSZ-13 obtained from the conventional methods.