A kind of molecular sieve with mtw structure and its preparation method and application
A molecular sieve and mesoporous structure technology, applied in molecular sieve catalysts, chemical instruments and methods, refined hydrocarbon oil, etc., can solve the problems of reducing interaction, mesoporous structure, molecular sieve acid weakening, etc.
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[0029] The invention also provides a preparation method of the molecular sieve with MTW structure. Generally, the preparation of aluminum-containing molecular sieves can be divided into steps such as gelation, crystallization, and post-treatment. In order to obtain the molecular sieve with MTW structure described in the present invention, the post-treatment step in the synthesis process of the aluminum-containing molecular sieve needs to be specially treated, and the specific steps are as follows:
[0030] (1) Filter the crystallized mother liquor to form a filter cake with a dry basis content of 5-30%;
[0031] (2) directly roasting the filter cake to obtain a molecular sieve precursor;
[0032] (3) subjecting the molecular sieve precursor to hydrothermal treatment;
[0033] (4) Filter, wash and dry the hydrothermally treated product.
[0034] In step (1), the purpose of filtering the crystallized mother liquor is to remove the synthesis mother liquor. The present inventi...
Embodiment 1
[0052] (1) Preparation of crystallized mother liquor
[0053] Take 38.5mL containing 40% by weight of SiO 2 Silica sol, 1.48 grams of analytically pure sodium aluminate, and 17.5 mL of tetraethylammonium hydroxide (40% by weight) were used for later use. Mix tetraethylammonium hydroxide, sodium aluminate and 37 grams of deionized water, then add silica sol, stir for 1 hour, then transfer to a reaction kettle, and crystallize at 160°C for 132 hours.
[0054] (2) Preparation of filter cake
[0055] Filter the crystallized mother liquor prepared in step (1), and continue suction filtration for 5 minutes when there is no filtrate on the filter cake. The filter cake F-1 obtained has a dry basis content of 11.2 %, the silica / alumina molar ratio is 30.2.
[0056] (3) Preparation of molecular sieve precursor
[0057] The filter cake F-1 was raised from room temperature to 450° C. at a heating rate of 25° C. / min, and kept at a constant temperature for 4 hours. During the heating p...
Embodiment 2
[0064] The molecular sieve with MTW structure was prepared according to the method of Example 1, except that in step (3), the filter cake F-1 was raised from room temperature to 350°C at a heating rate of 5°C / min, and kept at a constant temperature for 14 hours. During the heating process, the roasting furnace is a closed roasting furnace to obtain the molecular sieve precursor C-2. The finished product H-2 of molecular sieve with MTW structure was obtained.
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