METHOD FOR SYNTHESIS OF SILICOALUMINOPHOSPHATE-34 MOLECULAR SIEVES Russian patent published in 2019 - IPC B01J29/85 C01B39/54 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of synthesis of small crystals of silicoaluminophosphate-34 (SAPO-34) molecular sieves with high structural purity, to catalyst particles for converting methanol to olefins, containing SAPO-34 molecular sieves, and a method of producing olefins. Method of synthesis of molecular sieves of silica-aluminophosphate-34 (SAPO-34) includes: forming a first suspension containing a first phosphorus source, a first aluminium source, a first silicon source and at least one first organic structure-forming agent; holding first suspension at temperature in range from approximately room temperature to approximately 200 °C for a period of time greater than 0.5 hours, to form a first maintained suspension; formation of a second suspension containing a second phosphorus source, a second aluminium source, a second silicon source and at least one second organic structure-forming agent; holding second suspension at temperature in range from approximately 10 °C to approximately 150 °C for a time in the range from about 0.5 hour to about 50 hours to form a second maintained suspension; formation of a mixture of aged suspensions by combining a first maintained suspension and a second maintained suspension; and initiating crystallisation of silicoaluminophosphate molecular sieves containing SAPO-34 molecular sieves from a mixture of aged suspensions. At least one first organic structure-forming agent in the first suspension differs from at least one second organic structure-forming agent in the second suspension; first phosphorus source can be the same as or be different from phosphorus second source; first aluminium source can be the same as the second aluminum source, or can differ from it; and the first silicon source can be the same as the second silicon source, or can differ from it. In the method, the crystallisation initiation step includes: (1) initial heating of a mixture of aged suspensions to a first temperature in the range from about 50 °C to about 200 °C, and then holding mixture at first temperature for time in range from about 0.5 hour to about 24 hours; and (2) additional heating of maintained suspensions mixture to second temperature in range from approximately 150 °C to about 250 °C, and then holding mixture at second temperature for time in range from about 0.5 hour to about 70 hours. At least one first organic structure-forming agent is selected from a group consisting of quaternary ammonium compounds, alkanolamines and substituted or unsubstituted alkylamines, and at least one second organic structure-forming agent is selected from a group consisting of quaternary ammonium compounds, alkanolamines and substituted or unsubstituted alkylamines.

EFFECT: technical result is obtaining highly homogeneous crystals with high purity.

24 cl, 11 dwg, 1 tbl, 6 ex