Surface-modified zeolites and methods for preparing the same

A selectivation method for preparing a surface-modified zeolite, the method comprising the steps of:

• contacting a hybrid polymer, formed from a silicon alkoxide and a metal alkoxide, a co-monomer, or both, wherein said silicon alkoxide is selected from the group consisting of tetramethyl orthosilicate (TMOS), a tetraethyl orthosilicate (TEOS), a tetrapropyl orthosilicate (TPOS), a tetrabutyl orthosilicate (TBOS), and combinations thereof, said metal alkoxide is selected from the group consisting of titanium alkoxides and zirconium alkoxides, and said comonomers are selected from the group consisting of bisacrylamides, bis-methacrylamides, bis-acrylates, ethylene glycol-methacyletes;
• and diallyltartradiamide, with a zeolite suspension comprised of a solvent and a zeolite selected from the group consisting of an ammonium-form zeolite, a hydrogen-form zeolite, and a sodium-form zeolite and wherein said zeolite is selected from the group consisting of MFI, MEL, MTW, TON, MTT, FER, EUO, IMF and TUN zeolites, under conditions sufficient to deposit the hybrid polymer on external surfaces of the zeolite to form a treated zeolite;
• removing the solvent from the treated zeolite;
• and
• drying and calcinating the treated zeolite to form a dried and calcinated treated zeolite, wherein forming of the zeolite suspension, and the contacting, removing, drying and calcinating steps comprise a selectivation sequence producing a surface-modified zeolite from the ammonium-form zeolite and the hydrogen-form zeolite;
• wherein if the dried and calcinated treated zeolite is a sodium-form zeolite, the method further comprises the steps of:
• exchanging sodium with ammonium at ion-exchangeable sites of the dried and calcinated treated zeolite;
• and
• additionally drying and calcinating the dried and calcinated treated zeolite.