Zeolitic materials with modified surface composition, crystal structure, crystal size, and/or porosity, methods for making the same, and methods for converting oxygenates to olefins via reactions catalyzed by the same

A method for reducing a surface silicon content of a silicon-containing zeolitic material, the method comprising the steps of:

• providing a zeolitic material comprising silicon at a surface of the zeolitic material, wherein the zeolitic material comprises a silico-alumino-phosphate (SAPO), a metal-substituted silicoaluminumphosphate (MeAPSO), or combinations thereof, wherein the zeolitic material comprises SAPO-34, metal-substituted SAPO-34, SAPO-18, metal-substituted SAPO-18, SAPO-56, SAPO-RHO, SAPO-5, or mixtures or intergrowths thereof;
• and
• contacting the surface of the zeolitic material with a modifying solution comprising one or more of an amine, or an alcoholamine, an alcoholamine with one, two, or three alcohol functionalities, a C1 to C4 chain length on an alcohol substituent, or both or wherein contacting the surface of the zeolitic material with a modifying solution comprises contacting the surface of the zeolitic material with a diethanolamine, or a combination thereof. wherein contacting the surface of the zeolitic material with the modifying solution reduces an amount of silicon at the surface to generate a modified zeolitic material with a reduced surface silicon content.