Shamzhy M. B-, Al-, Ga- and Fe-containing extra-large pore zeolites with UTL topology: synthesis, structure and catalytic properties

The influence of various synthesis parameters (i.e. gel composition, pH of reaction mixture, duration of crystallization) on the phase selectivity of zeolite formation in germanosilicate reaction medium in the presence of different three-valent heteroatoms E (E = B, Al, Ga, Fe) was systematically studied and compared with a controlled crystallization from pure germanosilicate media. The boundary conditions of the formation of the pure-phase of isomorphously substituted extra-large pore zeolite UTL were established. The influence of the nature of isomorphous substituent on sorption, acid and catalytic properties of the prepared extra-large pore UTL zeolites was established. It has been found that in comparison with germanosilicate reaction media the process of zeolite formation in E-containing reaction mixtures was characterized by longer induction period and the time of existence of the UTL phase, which increased in the following sequence: UTL < B-UTL < Fe-UTL < Ga-UTL << Al-UTL. It has been demonstrated that extra-large pore zeolites with UTL topology have advantages (e.g. increasing conversion value of the initial substrate or the selectivity to the desired products) as catalysts for acid-base transformations compared to large-pore zeolites (industrial zeolites BEA, MFI), due to the easier availability of acid sites and the larger volume of "nanoreactor".