Synthesis of zeolite films bonded to substrates, structures and uses thereof

A method for preparing a structure which comprises a medium pore zeolite film bonded to a substrate with minimal homogeneous nucleation, the method comprising:

• preparing a chemical mixture capable of forming the zeolite film wherein when the YO.sub.2 /X.sub.2 O.sub.3 ratio in the reaction mixture is greater than about 400, the mixture comprises a H.sub.2 O/YO.sub.2 molar ratio of at least 25, when the YO.sub.2 /X.sub.2 O.sub.3 is greater than about 150 and less than about 400, the H.sub.2 O/YO.sub.2 is at least about 35, when the YO.sub.2 /X.sub.2 O.sub.3 is less than about 150, the H.sub.2 O/YO.sub.2 is at least about 45, and Y is a tetravalent element and X is a trivalent element;
• contacting the substrate with the chemical mixture under crystallization conditions until a substantially continuous layer of zeolite forms as bonded to the substrate surface.