CN104386706A - Method for synthesizing CHA-type molecular sieve by using zinc-amine complex as template agent - Google Patents

Abstract

The invention relates to a method for synthesizing a CHA type molecular sieve by using a zinc amine complex as a template. It uses sodium metaaluminate, organic amine, silica sol, sodium hydroxide and soluble zinc salt as raw materials for hydrothermal reaction, and is characterized in that the aqueous solution of sodium metaaluminate is reacted with the soluble zinc salt solution added with tetraethylenepentamine , then add solid sodium hydroxide and silica sol, stir for 3-5 hours, put them into the reaction kettle, and crystallize at a temperature of 130-160°C for 2-8 days; Wash, dry in an oven at 70-95°C for 14-16 hours, heat exchange 0.1-1mol/L ammonium nitrate at 80-100°C for 2-15 hours and bake at 400-450°C for 6-8 hours to remove the template, to obtain the final product. The CHA-type molecular sieve synthesized by the invention has a high crystallinity, uses the zinc amine complex as a template to replace the expensive amantadine template molecule, greatly reduces the production cost, is beneficial to meet the needs of industrial production, and is used as a catalyst.

Description

Method for Synthesizing CHA Molecular Sieve Using Zinc Amine Complex as Template

technical field

The invention belongs to the field of molecular sieves and provides a method for cheaply synthesizing CHA type molecular sieves.

Background technique

Molecular sieve is a kind of porous material. Because of its regular and uniform pore structure, good adsorption performance and shape selectivity, it is used as the main catalytic material, adsorption separation material and ion exchange material in petroleum processing, petrochemical and fine chemical industry. And daily chemical industry is playing an increasingly important role. Due to the needs of the above three major fields, there are currently more than one hundred kinds of artificially synthesized molecular sieves, and there is still a lot of room for development in terms of the diversity of component elements and skeleton structures. However, so far only LTA type, FAU type, MOR type, LTL type, MFI type, BEA type, MTW type, CHA type, FER type, AEL type and TON type have been used on an industrial scale. Among them, CHA-type molecular sieves have shown high catalytic activity and selectivity in the MTO reaction of methanol to olefins, and thus have attracted extensive attention.

CHA-type molecular sieve (SSZ-13 molecular sieve) has an eight-membered ring channel structure, and SSZ-13 molecular sieve with a higher silicon-aluminum ratio shows higher hydrothermal stability and thermal stability in the reaction of methanol to olefins and is not easy to deactivate , is a hot spot for people to study. At present, the template agent widely used in the synthesis of SSZ-13 molecular sieve is 1-adamantamine TMAdaOH (N, N, N-trimethyl-1-1-adamantammonium hydroxide). The preparation method of the organic molecular sieve is complicated and expensive, so its application is limited. In 2006, it was mentioned in the US Patent No.60/826.882 applied by Zones et al. that they can significantly reduce the dosage of TMAda ⁺ cations by adding toluene quaternary ammonium ions and TMAda ⁺ cations together as the structure-directing agent of the reactant. But its synthesis cost is still high. Recently, Xiao Fengshou and others synthesized Cu-SSZ-13 molecular sieves in one step using copper amine complexes as templates in Chinese patent CN101973562 B. During the synthesis process, copper amine complexes are both template molecules and catalytically active components Direct source of copper species. Although this method avoids the use of expensive amantadine templates, the ion exchange capacity of the product is poor, copper ions are difficult to remove, and difficult to convert into SSZ-13, so the application field is relatively narrow.

Contents of the invention

The object of the present invention is to provide a method for synthesizing a CHA type molecular sieve using a zinc amine complex as a template. The method can provide a one-step hydrothermal method for synthesizing the SSZ-13 molecular sieve by using the zinc amine complex as a template agent.

To achieve the above object, the present invention adopts the following technical solutions:

In the present invention, sodium metaaluminate, organic amine, silica sol, sodium hydroxide and soluble zinc salt are used as raw materials for hydrothermal reaction, and the specific steps are to combine sodium metaaluminate aqueous solution with organic amine-added soluble zinc salt aqueous solution (i.e. generated Zn-R zinc amine complex) reaction, then add sodium hydroxide solid and silica sol, stir for 3-5 hours, put it into a reaction kettle, and crystallize at a temperature of 130-160°C for 2-8 days; the reaction is completed Finally, the reaction product is fully washed with deionized water, dried in an oven at 70-95°C for 14-16 hours, heated and exchanged by 1mol/L ammonium nitrate at 80-100°C for 2-10 hours, and roasted at 400-450°C for 6 -8 hours, the templating agent was removed to obtain the final product.

The molar ratio of each reaction raw material is: SiO ₂ : Al ₂ O ₃ : Na ₂ O: H ₂ O: Zn-R is 6.5-150: 1: 2-50: 200: 1.5-10. The Zn-R is a zinc amine complex, wherein Zn is a divalent zinc ion, and R is an organic amine complexed with zinc. The organic amine is tetraethylenepentamine. The soluble zinc salt is any one of zinc sulfate, zinc chloride, zinc nitrate and zinc acetate, and the molar ratio of Zn and R is 1:1.

The invention provides a new structure-directing agent for synthesizing SSZ-13 molecular sieve, that is, the complex of zinc and tetraethylenepentamine is used as the structure-directing agent. The directing agent is cheap, easy to remove, and has great industrial application prospects. The CHA-type molecular sieve synthesized by the invention has a high crystallinity, uses the zinc amine complex as a template to replace the expensive amantadine template molecule, greatly reduces the production cost, is beneficial to meet the needs of industrial production, and is used as a catalyst.

Description of drawings

Fig. 1: the XRD spectrogram of the product of embodiment 1; Fig. 2: the SEM picture of the product of embodiment 1.

Fig. 3: the XRD spectrogram of the product of embodiment 2; Fig. 4: the XRD spectrogram of the product of embodiment 3.

Fig. 5: the XRD spectrogram of the product of Example 4; Fig. 6: the XRD spectrogram of the product of Example 5.

Fig. 7: XRD spectrogram of the product of embodiment 6.

Detailed ways

The present invention will be described in further detail below through examples, which do not limit the protection scope of the present invention.

For the experimental methods that do not specify specific conditions in the examples, usually follow the conventional conditions and the conditions described in the manual, or follow the conditions suggested by the manufacturer. The materials and reagents used can be obtained from commercial sources unless otherwise specified.

Embodiment 1: the preparation of CHA sample

First, 1.134 grams of sodium metaaluminate was dissolved in 6.3 grams of deionized water to obtain solution A, 2.875 grams of zinc sulfate heptahydrate was dissolved in 6.3 grams of deionized water, stirred and dissolved for 0.5 hours, and then 1.893 grams of tetraethylenepentamine was added dropwise to obtain solution B. Then add solution B dropwise to solution A, and after fully stirring for 0.5 hours, add 1.05 grams of solid sodium hydroxide and 7.5 grams of silica sol, stir fully for 3 hours, put it into a reaction kettle, and crystallize at a temperature of 150 ° C. After the reaction was completed, the reaction product was fully washed with deionized water, and dried in an oven at 75 °C for 14 hours, and the template was removed by heat exchange at 90 °C for 6 h with 1 mol/L ammonium nitrate and roasted at 450 °C for 6 hours agent to obtain the final product; the molar ratio of each reaction raw material is: SiO ₂ : Al ₂ O ₃ : Na ₂ O: H _{2 O:} Zn-R is 10:1:2.5:200:2.

Accompanying drawing 1 is the XRD characterization result of the product, it can be seen that the product is a CHA structure, and has relatively high crystallinity.

Accompanying drawing 2 is the scanning electron microscope photo of the product, it can be seen that the particle size of the product is about cubic crystals of about 5nm.

Embodiment 2: the preparation of CHA sample

The feeding, steps, and treatment methods in the experiment were the same as in Example 1, except that the crystallization condition was crystallization at 140° C. for 5 days, and the reactor was taken out, filtered and washed to obtain product 2.

Accompanying drawing 3 is the XRD characterization result of the product, it can be seen that the product has a CHA structure, and the baseline of the spectrum is relatively flat, indicating that the product has a higher degree of crystallinity.

Embodiment 3: the preparation of CHA sample

In the experiment, the feeding, steps, and treatment methods were the same as in Example 2, except that the crystallization time was extended to 8 days, the reaction kettle was taken out, filtered and washed, and roasted at 450° C. for 6 hours to remove the template agent to obtain product 3.

Accompanying drawing 4 is the XRD characterization result of the product, it can be seen that the product is a CHA structure, and the crystallinity of the product is relatively high.

Embodiment 4: the preparation of CHA sample

The feeding, steps, and treatment methods in the experiment were the same as in Example 1, except that the crystallization conditions were crystallization at 160°C for 6 days, taking out the reaction kettle, washing with suction, and roasting at 450°C for 6 hours to remove the template agent to obtain product 3.

Accompanying drawing 5 is the XRD characterization result of the product, it can be seen that the product has a CHA structure, and the baseline of the spectrum is relatively flat, indicating that the product has a higher degree of crystallinity.

Embodiment 5: the preparation of CHA sample

The consumption of zinc sulfate heptahydrate is 4.313 grams, the consumption of tetraethylenepentamine is 2.840 grams, and the molar ratio of Zn-R and Al ₂ O ₃ in the feed is 3. Other feed intake, steps, processing method in the experiment are identical with embodiment 1. The resulting product is designated as product 5, and its XRD pattern is shown in Figure 6. The baseline of the XRD spectrum of product 5 is relatively flat, indicating that the crystallinity of the product is relatively high.

Embodiment 6: the preparation of CHA sample

The consumption of zinc sulfate heptahydrate is 5.750 g, the consumption _of tetraethylenepentamine is 3.786 g, and the molar ratio of Zn-R to _Al2O3 in the feed is 4. Other feed intake, steps, processing method in the experiment are identical with embodiment 1. The resulting product is designated as product 6, and its XRD pattern is shown in Figure 7. The baseline of the XRD spectrum of product 5 is relatively flat, indicating that the crystallinity of the product is relatively high.

Claims (5)

1. one kind with the method for zinc amine complex for template synthesis CHA type molecular sieve, it is for raw material carries out hydro-thermal reaction with sodium metaaluminate, organic amine, silicon sol, sodium hydroxide and soluble zinc salt, it is characterized in that the sodium metaaluminate aqueous solution and the soluble zinc salt reactant aqueous solution adding organic amine, add sodium hydrate solid and silicon sol again, stirring loaded in reactor after 3-5 hour, crystallization 2 ~ 8 days at the temperature of 130 ~ 160 DEG C; After having reacted, reaction product deionized water is fully washed, dry 14-16 hour in 70-95 DEG C of baking oven, at 80-100 DEG C, add heat exchange 2 ~ 15h by 0.1 ~ 1mol/L ammonium nitrate and at 400-450 DEG C of roasting 6-8 hour, removing template, obtains final product;

The mol ratio of described each reaction raw materials is: SiO ₂: Al ₂o ₃: Na ₂o: H ₂o: Zn-R is 6.5 ~ 150: 1: 2 ~ 50: 200: 1.5 ~ 10; Described Zn-R is zinc amine complex, and wherein Zn is the zine ion of divalence, and R is the organic amine with zinc complexing; The mol ratio of Zn, R is 1: 1.

2. method according to claim 1, is characterized in that the mol ratio of described each reaction raw materials is: SiO ₂: Al ₂o ₃: Na ₂o: H ₂o: Zn-R is 10: 1: 2.5: 200: 2.

3. method according to claim 1, is characterized in that described organic amine is tetraethylene pentamine.

4. method according to claim 1, is characterized in that described soluble zinc salt is any one in zinc sulfate, zinc nitrate, zinc chloride or zinc acetate.

5. method according to claim 1, is characterized in that Zn-R and Al in described reaction raw materials ₂o ₃mol ratio is: 1.5-10: 1.