Precious metal loaded ZSM-5 molecular sieve, and preparation method and application thereof

Abstract

The invention provides a method for in-situ synthesizing a precious metal loaded ZSM-5 molecular sieve. The method is characterized by comprising the following steps of stirring and mixing an aluminum source, water, a template agent solution and a precious metal saline solution; adding a silicon source, and stirring and mixing; crystallizing a mixture in a reaction kettle to obtain a crystal substance, and cleaning and drying to obtain the precious metal loaded ZSM-5 molecular sieve. The preparation method provided by the invention is simple, a preparation process of a traditional zeolite molecular sieve loaded precious metal catalyst is simplified, the steps of roasting and H2 reducing are saved, the operation cost is reduced, and the catalytic efficiency of the prepared molecular sieve on ortho-xylene is remarkably superior to the precious metal loaded ZSM-5 molecular sieve prepared through a traditional impregnation method.

Description

technical field

[0001] This field belongs to the field of catalysts, and relates to a noble metal-loaded ZSM-5 molecular sieve and its preparation method and application. Background technique

[0002] Volatile organic compounds (Volatile Organic Compounds, VOCs) are one of the important components of air pollutants, which pose serious hazards to the environment and human health. Therefore, it is of great environmental significance to effectively eliminate VOCs pollution. Among the many ways to eliminate VOCs, the catalytic oxidation method is the most practical control technology, and the noble metal Pd is one of the commonly used catalyst active components due to its good low-temperature activity and selectivity. Zeolite molecular sieves are widely used in the fields of gas separation, adsorption and catalysis due to their large specific surface area, regular, orderly and intertwined pores, large adsorption capacity and high hydrothermal stability. Since the preparation pr...

Examples

Embodiment 1

[0053] In the present invention, the in-situ synthesis of Pd-loaded ZSM-5 molecular sieves by the following method specifically includes the following steps:

[0054] (1) In a 200mL beaker, add 0.066g of sodium metaaluminate, 41.5g of deionized water, 24.5mL of tetra-n-propylammonium hydroxide (19.42%) and 15.6mL of palladium nitrate aqueous solution (1.4998×10 -3 g / ml), stirred at 25°C for 15min;

[0055] (2) Add 17.75 mL tetraethyl orthosilicate to the mixture obtained in step (1), and stir and mix at 25° C. for 5 h;

[0056] (3) The mixture obtained in step (2) was crystallized at 180° C. for 4 days in a reactor to obtain crystals, which were washed and dried to obtain Pd-loaded ZSM-5 molecular sieves.

Embodiment 2

[0058] In the present invention, in-situ synthesis of noble metal-supported ZSM-5 molecular sieves by the following method specifically includes the following steps:

[0059] (1) In a 200mL beaker, add 0.066g sodium metaaluminate, 13.2g deionized water, 13.5mL tetra-n-propylammonium hydroxide solution (concentration 15%) and 15mL palladium nitrate aqueous solution (2×10 -3 g / mL) was stirred and mixed for 30min at 20°C;

[0060] (2) Add 7 mL tetraethyl orthosilicate to the mixture obtained in step (1), and stir and mix at 20° C. for 10 h;

[0061] (3) The mixture obtained in step (2) was crystallized at 150° C. in a reaction kettle for 8 days to obtain a crystal, which was washed and dried to obtain a Pd-loaded ZSM-5 molecular sieve.

Embodiment 3

[0063] In the present invention, in-situ synthesis of noble metal-supported ZSM-5 molecular sieves by the following method specifically includes the following steps:

[0064] (1) In a 200mL beaker, add 0.066g of sodium metaaluminate, 52.8g of deionized water, 26.5mL of tetra-n-propylammonium hydroxide solution (concentration 25%) and 19.5mL of palladium nitrate aqueous solution (1×10 -3 g / mL) was stirred and mixed for 5 min at 30°C;

[0065] (2) Add 20 mL tetraethyl orthosilicate to the mixture obtained in step (1), and stir and mix at 35° C. for 3 h;

[0066] (3) The mixture obtained in step (2) was crystallized at 200° C. for 1 day in a reactor to obtain a crystal, which was washed and dried to obtain a Pd-loaded ZSM-5 molecular sieve.

technical field

[0001] This field belongs to the field of catalysts, and relates to a noble metal-loaded ZSM-5 molecular sieve and its preparation method and application. Background technique

[0002] Volatile organic compounds (Volatile Organic Compounds, VOCs) are one of the important components of air pollutants, which pose serious hazards to the environment and human health. Therefore, it is of great environmental significance to effectively eliminate VOCs pollution. Among the many ways to eliminate VOCs, the catalytic oxidation method is the most practical control technology, and the noble metal Pd is one of the commonly used catalyst active components due to its good low-temperature activity and selectivity. Zeolite molecular sieves are widely used in the fields of gas separation, adsorption and catalysis due to their large specific surface area, regular, orderly and intertwined pores, large adsorption capacity and high hydrothermal stability. Since the preparation pr...

Examples

Embodiment 1

[0053] In the present invention, the in-situ synthesis of Pd-loaded ZSM-5 molecular sieves by the following method specifically includes the following steps:

[0054] (1) In a 200mL beaker, add 0.066g of sodium metaaluminate, 41.5g of deionized water, 24.5mL of tetra-n-propylammonium hydroxide (19.42%) and 15.6mL of palladium nitrate aqueous solution (1.4998×10 -3 g / ml), stirred at 25°C for 15min;

[0055] (2) Add 17.75 mL tetraethyl orthosilicate to the mixture obtained in step (1), and stir and mix at 25° C. for 5 h;

[0056] (3) The mixture obtained in step (2) was crystallized at 180° C. for 4 days in a reactor to obtain crystals, which were washed and dried to obtain Pd-loaded ZSM-5 molecular sieves.

Embodiment 2

[0058] In the present invention, in-situ synthesis of noble metal-supported ZSM-5 molecular sieves by the following method specifically includes the following steps:

[0059] (1) In a 200mL beaker, add 0.066g sodium metaaluminate, 13.2g deionized water, 13.5mL tetra-n-propylammonium hydroxide solution (concentration 15%) and 15mL palladium nitrate aqueous solution (2×10 -3 g / mL) was stirred and mixed for 30min at 20°C;

[0060] (2) Add 7 mL tetraethyl orthosilicate to the mixture obtained in step (1), and stir and mix at 20° C. for 10 h;

[0061] (3) The mixture obtained in step (2) was crystallized at 150° C. in a reaction kettle for 8 days to obtain a crystal, which was washed and dried to obtain a Pd-loaded ZSM-5 molecular sieve.

Embodiment 3

[0063] In the present invention, in-situ synthesis of noble metal-supported ZSM-5 molecular sieves by the following method specifically includes the following steps:

[0064] (1) In a 200mL beaker, add 0.066g of sodium metaaluminate, 52.8g of deionized water, 26.5mL of tetra-n-propylammonium hydroxide solution (concentration 25%) and 19.5mL of palladium nitrate aqueous solution (1×10 -3 g / mL) was stirred and mixed for 5 min at 30°C;

[0065] (2) Add 20 mL tetraethyl orthosilicate to the mixture obtained in step (1), and stir and mix at 35° C. for 3 h;

[0066] (3) The mixture obtained in step (2) was crystallized at 200° C. for 1 day in a reactor to obtain a crystal, which was washed and dried to obtain a Pd-loaded ZSM-5 molecular sieve.

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