Ti-MWW@Si molecular sieve of core-shell structure and preparation method and application of molecular sieve
A core-shell structure and molecular sieve technology, applied in molecular sieve catalysts, chemical instruments and methods, crystalline aluminosilicate zeolites, etc., can solve the problems of low yield of propylene oxide and hindering the diffusion of reactive molecules, so as to improve the reactivity, Improve hydrophobicity and reduce deactivation effect
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Embodiment 1
[0041] (1) Dispersing 10.0 g of Ti-MWW molecular sieve grains prepared according to Comparative Example 1 in 18.57 g of glucose aqueous solution with a concentration of 15 wt % to form a suspension slurry, and then rotating the mixed slurry at 60° C. to dry in vacuum to remove moisture, so that Glucose molecules are enriched on the surface of Ti-MWW molecular sieve grains, and then on the N 2 Calcined at 500° C. for 2 hours under atmosphere to obtain carbon-deposited C-Ti-MWW molecular sieve.
[0042] (2) Template agent CTAB, template agent P123, ammonia water NH 3 ·H 2 O. Ultrasonic dispersion of absolute ethanol EtOH and deionized water, mechanical stirring at 40°C for 1h, then cooling down to 25°C, adding TEOS and stirring vigorously at 1000rpm for 5min to obtain a mixed solution, its components according to the molar ratio TEOS:CTAB:P123 :EtOH:NH 3 :H 2 O=1:0.16:0.005:81:20:665, and then the C-Ti-MWW molecular sieve obtained in (1) was uniformly dispersed with the abov...
Embodiment 2～8
[0044] (1) Same as in Example 1, 10.0 g of Ti-MWW molecular sieve grains were dispersed in an aqueous glucose solution to form a suspension slurry. The concentration and quality of the glucose solution are shown in Table 1. Then, the mixed slurry was rotated and vacuum-dried at 50-90°C (the specific temperature is shown in Table 1) to remove moisture, so that glucose molecules were enriched on the surface of Ti-MWW molecular sieve grains, and then dried under N 2 Calcination under atmosphere (temperature and calcination time are shown in Table 1) to obtain carbon-deposited C-Ti-MWW molecular sieves.
[0045] (2) same as embodiment 1, template agent CTAB, template agent P123, ammoniacal liquor (NH 3 ·H 2 O), absolute ethanol (EtOH) and deionized water H2O were uniformly dispersed by ultrasonic at 40°C, and mechanically stirred for 1h, then cooled to 25°C and added with alkyl silicate (different examples are shown in Table 2) and 1000rpm Stir vigorously at a rotating speed for...
Embodiment 9～16 and comparative example 3～7
[0053] Propylene epoxidation was carried out in a 1000 mL stainless steel reactor with a polytetrafluoroethylene liner.
[0054] With 150mg embodiment 1~8 and comparative example 1~2 titanium silicate molecular sieve catalyst, 30ml concentration is the H of 30.0wt%. 2 o 2 And 60ml of pure solvent is added in the reaction kettle, seal the reaction kettle, pass the air in the propylene replacement reaction kettle three times, then raise the temperature to 40 ℃, start to feed propylene reaction continuously (reaction pressure, propylene decompression maximum pressure 3.0MPa), the reaction After 2 hours. Stop the reaction, put the reaction kettle into ice water and cool to 15°C, add isopropanol as a solution of internal standard and solvent to the reacted mixture, mix well and analyze by gas chromatography, the results are shown in Table 3. The reaction solution was titrated with cerium sulfate for remaining perhydrous 2 o 2 , to determine the H used 2 o 2 quantity.
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