CN1116112C - Method of in-situ synthesizing ferrierite on lumpy cordierite honeycomb ceramic carrier - Google Patents

Abstract

A method for synthesizing in-situ ferrierite SiO ₂ zeolite on a block cordierite honeycomb ceramic carrier, first uniformly dip-coating a layer of gel solution containing Al ₂ O ₃ and Na ₂ O on the surface of the carrier, characterized in that: crystallize the dip-coated support under the mixed saturated vapor pressure of organic amine and water at 150-200°C for 3-10 days, so that ferrierite grows on the surface of the support in situ in the form of gas-solid phase transformation; the organic The amine is selected from ethylenediamine, triethylamine, and pyrrolidine, and the molar ratio of organic amine to water is 1: (0.5-10). The dip coating of the invention is uniform and firm, applicable to carriers of various shapes, and does not cause environmental pollution.

Description

A method for in-situ synthesis of ferrierite on bulk cordierite honeycomb ceramic carrier

technical field

The invention provides a method for synthesizing ferrierite in situ on a cordierite block honeycomb ceramic carrier.

Background technique

Loaded zeolite molecular sieves are widely used in petrochemical and environmental protection fields due to their high mechanical strength, low pressure drop, and excellent heat and mass transfer properties. For example, membrane reactors used in petrochemical separation processes and catalytic converters used to eliminate automobile exhaust all use zeolite molecular sieves loaded on various carriers as the main component of the catalyst. There are generally two methods for loading zeolite molecular sieves. One is the washcoat method, that is, the carrier is immersed in a slurry containing zeolite molecular sieve, so that a layer of zeolite molecular sieve is loaded on the surface of the carrier. Patents JP0418914 and JP07132230 both use dip-coating technology to load a layer of Cu-ZSM-5 molecular sieve on the surface of honeycomb ceramics to eliminate automobile exhaust. JP0847644 uses dip-coating technology to load zeolite molecular sieves and other oxides on the surface of honeycomb ceramics to eliminate automobile exhaust. Although the dip coating method has the advantages of uniform dip coating, simple operation and wide adaptability, its serious disadvantage is that the combination of the dip coating and the surface of the carrier is not firm. Impact, the molecular sieve layer is easy to peel off from the surface of the carrier, thus greatly reducing its catalytic performance. Another method for loading molecular sieves is in situ synthesis technology (insitusynthesis), that is, in situ synthesis of molecular sieves is carried out on the surface of the carrier, so that a layer of molecular sieve crystals can be firmly grown on the surface of the carrier. Patent USP4800187 uses in-situ synthesis technology to synthesize a variety of molecular sieves on the surface of honeycomb ceramics. Patent USP4904518 hydrothermally synthesizes various molecular sieves such as ZSM-5, ZSM-11, ZSM-12, and ZSM-20 on the surface of silicon wafers. However, the above patents The disadvantage of the hydrothermal synthesis technology used is that the molecular sieves grow unevenly on the surface of the carrier, especially when the shape of the carrier is complex, such as honeycomb ceramics or foam ceramics with a number of pores greater than 300cells/inch ² , the disadvantage of the hydrothermal synthesis technology is more obvious.

Contents of the invention

The object of the present invention is to provide a method for synthesizing ferrierite in situ on a block cordierite honeycomb ceramic carrier. The dipping method is uniform and firm, is applicable to carriers of various shapes, and does not generate environmental pollution.

The invention provides a method for synthesizing in-situ ferrierite SiO ₂ zeolite on a bulky cordierite honeycomb ceramic carrier. First, evenly dip-coat a layer of gel solution containing Al ₂ O ₃ and Na ₂ O on the surface of the carrier, It is characterized in that: the dip-coated carrier is crystallized under the mixed saturated vapor pressure of organic amine and water at 150-200°C for 3-10 days, so that ferrierite grows on the surface of the carrier in situ in the form of gas-solid phase transformation ; The organic amine is selected from ethylenediamine, triethylamine, pyrrolidine, and the molar ratio of the organic amine to water is 1: (0.5-10).

The composition of the gel used as the dipping solution in the present invention may be a molar ratio of Al ₂ O ₃ :(3-15)SiO ₂ :(1-10)Na ₂ O:(500-6000)H ₂ O.

Due to a series of chemical changes in the crystallization process of the present invention, the surface of the carrier is very firmly combined with the ferrierite layer, while maintaining the uniformity of the dip coating method. The mother liquor composed of organic amine and water can be reused, which not only saves raw materials, but also avoids environmental pollution caused by waste mother liquor.

Detailed ways

Below by example the method of the present invention is given further description.

Example 1

The bulk honeycomb ceramic carrier with a volume of 5ml, 400cells/inch ² was treated with 1N HNO ₃ solution at 80°C for 1h, and then washed with deionized water until neutral. Dry at 120°C for 6h, and bake at 500°C for 3h.

Dissolve 1.8801g of Al ₂ (SO ₄ ) ₃ , 18H ₂ O in 15ml of water to obtain solution 1. Dissolve 6.4320g of silica sol in 15ml of water to obtain solution 2. Slowly drop solution 2 into solution 1 to obtain a gel solution. Another 1.1280g of NaOH was dissolved in 5ml of water and dropped into the above gel solution.

Immerse the surface-treated bulk honeycomb ceramic carrier in the prepared gel for about 5 minutes, take it out, and hang it in a 125ml kettle with a stainless steel wire. 6 ml of ethylenediamine and 6 ml of water were placed at the bottom of the kettle. After the kettle was sealed, it was placed in an oven at 160°C for crystallization for 8 days. After cooling, the carrier was taken out and washed with deionized water until neutral. After drying, do XRD characterization. The result is as follows:

2θ dspacing 100×I/I ₀

7.8 11.325 6

9.6 9.205 6

10.4 8.499 100

18.08 4.902 27

18.96 4.676 15

20.8 4.267 4

21.68 4.095 56

22.2 4.001 7

23 3.863 12

23.68 3.754 8

25.52 3.487 10

26.36 3.378 58

27.76 3.211 2

28.4 3.14 67

29.44 3.031 74

32.8 2.728 4

33.88 2.643 22

36.76 2.442 6

37.16 2.417 4

38.52 2.335 11

39.52 2.278 4

The above results prove that the support consists of cordierite and pure ferrierite.

Analysis by scanning electron microscope (SEM) proved that a layer of ferrierite with a thickness of about 20 μ was grown on the surface of the carrier. The destruction experiment with a sharp instrument shows that the combination of ferrierite and the surface of the carrier is very firm, even if the carrier itself is destroyed, the zeolite layer grown on it cannot fall off.

Example 2

The treatment of the surface of the carrier and the preparation of the gel were exactly the same as in Example 1, except that 2ml of ethylamine, 4ml of ethylenediamine and 6ml of water were charged at the bottom of the synthesis kettle. Its XRD results prove that the carrier is composed of cordierite, ferrierite and a small amount of impurities. Scanning electron microscope results showed that the thickness of the ferrierite layer grown on the cordierite surface was about 10μ.

Example 3

The treatment of the surface of the carrier and the preparation of the gel are exactly the same as in Example 1, except that 6 ml of pyrrolidine and 6 ml of water are charged at the bottom of the synthesis kettle. Its XRD results prove that the carrier is composed of cordierite and ferrierite, and no other impurities are formed.

Example 4

Other conditions are exactly the same with embodiment 1, just the liquid phase part in the kettle reuses the used liquid phase of embodiment 1. The XRD results showed that a layer of ferrierite grew on the surface of the carrier.

Example 5

Other conditions are exactly the same with embodiment 2, just the liquid phase part in the still reuses the used liquid phase of embodiment 2. The XRD results showed that a layer of ferrierite grew on the surface of the carrier.

Example 6

Other conditions are identical with embodiment 3, just the liquid phase part in the still reuses the used liquid phase of embodiment 3. The obtained carrier was characterized by XRD, which proved that a layer of ferrierite grew on the surface of the carrier.

Example 7

The bulk honeycomb ceramic carrier with a volume of 5ml and 400cel1s ^/ inch was treated with 10% H ₂ O ₂ solution at 80°C for 1 h, followed by 10% NH ₄ Cl solution for 1 h, and then washed with deionized water to medium sex. Dry at 120°C for 6h, and bake at 500°C for 3h. The preparation and dip coating of the gel are exactly the same as in Example 1. The XRD results showed that a layer of ferrierite grew on the surface of cordierite. Scanning electron micrographs show that the thickness of the ferrierite layer is about 30μ.

Example 8

Other conditions are exactly the same as in Example 3, except that the crystallization temperature is 150° C., and the XRD result proves that a layer of ferrierite grows on the surface of the cordierite.

Claims (1)

1. A method for synthesizing magnesium alkali SiO ₂ zeolite in situ on a massive cordierite honeycomb ceramic carrier, first uniformly dip-coating a layer of Al ₂ O ₃ and Na ₂ O gel solution on the carrier surface, its characteristics The method is: crystallize the dip-coated carrier under the mixed saturated vapor pressure of organic amine and water at 150-200°C for 3-10 days, so that the ferrierite grows on the surface of the carrier in situ in the form of gas-solid phase transformation; The organic amine is selected from ethylenediamine, triethylamine, pyrrolidine, and the molar ratio of the organic amine to water is 1: (0.5-10); wherein the gel composition used as the dipping solution is a molar ratio of Al ₂ O ₃ : (3-15) SiO ₂ : (1-10) Na ₂ O: (500-6000) H ₂ O.