CN1393402A - Process for preparing nano Y zeolite molecular sieve carried by kaolin microspheres - Google Patents

Abstract

A preparation method of nano zeolite molecular sieve Y loaded on kaolin microspheres. Its steps: 1) preparing the guiding agent; 2) taking the guiding agent and adding sodium citrate, stirring magnetically for 1.5-3 hours; the weight ratio of the guiding agent and sodium citrate is 65-75:2.5-3.5; 3) roasting the Kaolin microspheres are added to the solution in step 2), and mechanically stirred, the weight ratio of the amount added to the solution is 65-75: 4-15; 4) sulfuric acid solution is added dropwise, and the amount added is the weight of the solution described in step 3) 23% to 32% of the concentration, and the concentration is 28% to 32%, to obtain a gel, shake evenly and crystallize at 90°C to 110°C; 5) separate the above product to obtain the nano zeolite molecular sieve Y product supported by kaolin microspheres. It has good hydrothermal stability.

Description

Preparation method of nano zeolite molecular sieve Y supported by kaolin microspheres

The invention relates to in-situ synthesis and supported nanometer zeolite molecular sieve Y grain catalyst, in particular to a preparation method of nanometer zeolite molecular sieve Y supported by kaolin microspheres.

The catalyst mixed with zeolite molecular sieve Y and kaolin has important application in catalytic cracking process. Catalyst made of nano zeolite molecular sieve Y can increase the yield of diesel oil, but the hydrothermal stability needs to be improved. In the prior art, the preparation process of nano-zeolite Y molecular sieve has the problem of difficult separation and industrial application; the poor hydrothermal stability of nano-zeolite Y molecular sieve is also an important reason restricting its application. In addition, after adding a directing agent or seed crystal into the kaolin slurry, it is spray-dried into kaolin microspheres, and in a system for synthesizing zeolite molecular sieve Y, a product containing 40% of zeolite molecular sieve Y is synthesized. For example: U.S. Patent (Patent No. 4493902, date of application on January 15, 1985) discloses a method for in-situ crystallization on kaolin microspheres to synthesize zeolite molecular sieve Y grains, which is characterized in that it is added before kaolin microspheres are formed. The so-called seed crystals are then crystallized in situ to form zeolite molecular sieve Y.

The object of the present invention is to provide a preparation method of nano zeolite molecular sieve Y loaded on kaolin microspheres with easy separation and good hydrothermal stability.

The technical scheme of the present invention is: crystal grain is grown on the kaolin microsphere, and concrete steps are:

(1) Preparation of directing agent:

1) Weigh silica sol with a concentration of 28-32%, add NaOH in a weight ratio of 55-65:15-25, and shake to dissolve;

2) Separately weigh water according to the weight ratio of 40～45:10～15:8～12, add Al ₂ (SO ₄ ) ₃ ·18H ₂ O and NaOH, stir and dissolve; 28-32% concentration of silica sol and Al ₂ ( The weight ratio of SO ₄ ) ₃ ·18H ₂ O is 55～65:10～15;

3) adding the solution described in step 2) into the solution described in step 1), stirring magnetically for 1 to 3 hours, and aging at room temperature for 1 to 15 days to make a directing agent;

(2) Take the above-mentioned directing agent and add sodium citrate, and magnetically stir for 1.5 to 3 hours; wherein the weight ratio of directing agent to sodium citrate is 65 to 75: 2.5 to 3.5;

(3) Add the kaolin microspheres roasted at 600-650°C to the solution of step (2), and mechanically stir for 5-8 hours, the weight ratio of the amount added to the solution is 4-15: 65-75;

(4) drop into sulfuric acid solution, the drop-in amount is 23～32% of the solution weight described in the step (3), and concentration is 28～32%, obtains gel, crystallizes at 90～110 ℃ after oscillating evenly 8 ~12 hours;

(5) The above product is taken out for separation, suction filtration, washing and drying to obtain a growth product containing zeolite crystal grains.

The present invention has the following advantages:

1. The process is simple. The invention uses the highly basic directing agent to interact with the loaded zeolite molecular sieve Y crystal grains, and the 80-200 nanometer zeolite molecular sieve Y crystal grains can be grown on the kaolin microspheres.

2. Good hydrothermal stability. The zeolite molecular sieve Y crystal grains prepared by the present invention are grown on kaolin microspheres, and the hydrothermal stability of the zeolite molecular sieve Y crystal grains carried is good, which is obviously higher than that of molecular sieve Y crystal grains not grown on kaolin microspheres. Stability (see Figure 1). Molecular sieve Y not grown on kaolin microspheres lost almost all of its crystallinity after hydrothermal treatment at 650°C, indicating that most of it was transformed into an amorphous substance, and its hydrothermal stability was poor; while the supported zeolite molecular sieve Y There is little change in crystallinity after heat treatment.

3. Easy to separate. Since the invention adopts the measure of directly growing the nanometer Y grains on the kaolin microspheres, the problem of difficulty in filtering in the large-scale industrial production of nanometer molecular sieves is solved.

Fig. 1 is an X-ray diffraction (XRD) spectrum of crystallinity of Y molecular sieve according to Example 1 of the present invention.

The present invention is described in detail below in conjunction with embodiment and accompanying drawing.

Example 1

To grow crystal grains on kaolin microspheres, the specific steps are:

(1) Preparation of directing agent:

Weigh 60.1g of 30% silica sol into a 250ml round bottom beaker, add 19.5g of NaOH, shake to dissolve safely; take a small beaker, weigh 42g of water, add 12.5g of Al ₂ (SO ₄ ) ₃ 18H ₂ O, 9g NaOH, stir to dissolve completely; then, add it to the previous 250ml round bottom beaker, stir it magnetically for 1 hour, and age at room temperature for 5 days;

(2) Take 71.6g of the aging guiding agent, add 2.8g of sodium citrate, and stir magnetically for 2 hours;

(3) Add 6.0 g of kaolin microspheres roasted at 600° C. to the beaker of step (2), and mechanically stir for 6 hours;

(4) 25.5 g of prepared sulfuric acid solution (15.4 g of calibrated 98% concentrated sulfuric acid, diluted into 35.6 g of water) was added dropwise, the obtained gel was shaken evenly, and crystallized at 100° C. for 10 hours;

(5) Take out and separate, suction filter, wash, and dry in an oven at 120°C to obtain about 4 grams of powder (c) product of kaolin microspheres loaded with nano zeolite molecular sieve Y, containing about 20% of zeolite molecular sieve Y crystal grains, and The size is 100-200nm; and the powder (a) of nano zeolite molecular sieve Y not grown on kaolin microspheres.

As shown in FIG. 1 , the nano Y powder (a) obtained in Example 1 was treated with 100% water vapor at 650° C. for 2 hours to obtain the nano Y powder (b). The kaolin microsphere-supported nano-Y (c) prepared by in-situ crystallization in Example 1 was treated with 100% water vapor at 650° C. for 2 hours to obtain the kaolin microsphere-supported nano-Y (d). Figure 1 compares the changes in the crystallinity of Y molecular sieves. It can be seen that the crystallinity of molecular sieve Y not grown on kaolin microspheres is almost completely lost after hydrothermal treatment at 650 °C, indicating that most of them are transformed into amorphous substances, and their hydrothermal stability is poor; while the supported zeolite molecular sieve Y The crystallinity did not change much after hydrothermal treatment at 650 °C. Therefore, the kaolin microspheres prepared by in-situ crystallization are more stable than the nano-Y powder loaded with nano-Y.

Example 2

To grow grains on kaolin microspheres, the specific steps are:

(1) Preparation of directing agent:

Weigh 57g of 32% silica sol into a 250ml round bottom beaker, add 25g of NaOH, shake to dissolve safely; take a small beaker, weigh 40g of water, add 15g of Al ₂ (SO ₄ ) ₃ 18H ₂ O, 12g of NaOH, stir Make it completely dissolved; then, add it to the previous 250ml round bottom beaker, stir it magnetically for 1 hour, and age it at room temperature for 15 days;

(2) Take 65g of the aging guiding agent, add 3.5g of sodium citrate, and stir magnetically for 3 hours;

(3) Add 10.0 g of kaolin microspheres calcined at 650° C. into the beaker of step (2), and mechanically stir for 8 hours;

(4) 18 g of prepared sulfuric acid solution (32% concentration) was added dropwise, the obtained gel was shaken evenly, and crystallized at 110° C. for 8 hours;

(5) Take out and separate, suction filter, wash, and dry in an oven at 120° C. to obtain about 7 grams of a powder product of nano-zeolite molecular sieve Y grown on kaolin microspheres, containing about 20% of zeolite molecular sieve Y grains, and the grain size It is 80~150nm.

Example 3

To grow crystal grains on kaolin microspheres, the specific steps are:

(1) Preparation of directing agent:

Weigh 65g of 28% silica sol into a 250ml round bottom beaker, add 15g of NaOH, shake to dissolve safely; take a small beaker, weigh 45g of water, add 10g of Al ₂ (SO ₄ ) ₃ 18H ₂ O, 11g of NaOH, stir Make it completely dissolved; then, add it to the previous 250ml round bottom beaker, stir it magnetically for 1 hour, and age it at room temperature for 8 days;

(2) Take 75g of the aging guiding agent, add 2.5g of sodium citrate, and stir magnetically for 1.5 hours;

(3) Add 4.0 g of kaolin microspheres roasted at 630° C. into the beaker of step (2), and stir mechanically for 5 hours;

(4) 22.4 g of prepared sulfuric acid solution (concentration 28%) was added dropwise, the obtained gel was shaken evenly, and crystallized at 90° C. for 12 hours;

(5) Take out and separate, suction filter, wash, and dry in an oven at 120° C. to obtain about 3 grams of a powder product of nano-zeolite molecular sieve Y grown on kaolin microspheres, containing about 20% of zeolite molecular sieve Y grains, and the grain size 10-200nm.

Claims (1)

1. A preparation method for carrying nanometer zeolite molecular sieve Y on kaolin microspheres, characterized in that: growing crystal grains on kaolin microspheres, the specific steps are: (1) Preparation of directing agent: 1) Weigh silica sol with a concentration of 28-32%, add NaOH in a weight ratio of 55-65:15-25, and shake to dissolve; 2) Separately weigh water according to the weight ratio of 40～45:10～15:8～12, add Al ₂ (SO ₄ ) ₃ ·18H ₂ O and NaOH, stir and dissolve; 28-32% concentration of silica sol and Al ₂ ( The weight ratio of SO ₄ ) ₃ ·18H ₂ O is 55～65:10～15; 3) adding the solution described in step 2) into the solution described in step 1), stirring magnetically for 1 to 3 hours, and aging at room temperature for 1 to 15 days to make a directing agent; (2) Take the above-mentioned directing agent and add sodium citrate, and magnetically stir for 1.5 to 3 hours; wherein the weight ratio of directing agent to sodium citrate is 65 to 75: 2.5 to 3.5; (3) Add the kaolin microspheres roasted at 600-650°C to the solution of step (2), and mechanically stir for 5-8 hours, the weight ratio of the amount added to the solution is 4-15: 65-75; (4) drop into sulfuric acid solution, the drop-in amount is 23～32% of the solution weight described in the step (3), and concentration is 28～32%, obtains gel, crystallizes at 90～110 ℃ after oscillating evenly 8 ~12 hours; (5) The above product was taken out for separation, suction filtration, washing, and drying to obtain a nano-zeolite molecular sieve Y product supported on kaolin microspheres.

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