CN102153105A

CN102153105A - Method for preparing MFI/MEL (Mobil Fifth/Mobil Eleven) eutectic molecular sieve

Info

Publication number: CN102153105A
Application number: CN2010106169706A
Authority: CN
Inventors: 王一萌; 朱树燕; 何鸣元
Original assignee: East China Normal University
Current assignee: East China Normal University
Priority date: 2010-12-31
Filing date: 2010-12-31
Publication date: 2011-08-17

Abstract

The invention discloses a method for preparing an MFI/MEL (Mobil Fifth/Mobil Eleven) eutectic molecular sieve. The method comprises the following steps of: (1) uniformly mixing a silicon source, an organic template agent, water and other components in mol ratio according to an MEL structural molecular sieve synthesizing way which is familiar by professionals; (2) adding alcohol into the mixture, loading the mixture into a reactor after uniformly stirring, crystallizing at 100-200 DEG C, filtering and drying to obtain the MFI/MEL eutectic structure molecular sieve, wherein the silicon dioxide molar ratio of alcohol to molecular sieve mother liquor is 0.5-5. In the invention, small molecular alcohol is added, and the MFI/MEL eutectic molecular sieve can be simply and effectively formed. The method disclosed by the invention has wide application range and can be applied to different synthesis systems; and the adopted small molecular alcohol is available.

Description

A kind of method for preparing the MFI/MEL eutectic molecular sieve

Technical field

The present invention relates to the molecular sieve synthesis technical field, specifically a kind of method of synthetic MFI/MEL eutectic molecular sieve.

Technical background

Because it is more concentrated that single molecular sieve bore diameter distributes, and separately to the catalytic performance difference of same reaction thing, is unfavorable for the raw material of process element complexity.The eutectic molecular sieve that contains two or more components has multifarious duct effect and acidity, can show the good catalytic activity that mechanical mixture did not have of single molecular sieve or two kinds of molecular sieves.

ZSM-5 and ZSM-11 belong to the pentasil molecular sieve with 5 ring structures, have MFI and MEL structure respectively.Because MFI and MEL similar, therefore be easy to form ZSM-5/ZSM-11 eutectic zeolite, it can be used for the catalyzer that alkylating aromatic hydrocarbon, alkane aromatization, methanol conversion are process such as low-carbon alkene.The ZSM-5/ZSM-11 eutectic shows excellent anti-sulphur and anti-water vapour ability in the preparing ethylbenzene from dry gas process, therefore have high conversion, highly selective and good regeneration.

Wang Qing is far to wait the people with C ₂-C ₈Diamine be template, introduce the rare earth element at water glass, aluminium source, mineral acid and synthesize ZSM-5/ZSM-11 eutectic structure zeolite (CN 1137022A) in zeolite, this zeolite forms the chemical constitution formula of expressing: XNa at anhydrous state synthetic oxide mol ratio ₂OYRE ₂O ₃Al ₂O ₃ZSiO ₂, X=0.1-1.0 wherein, Y=0.01-1.0, Z=20-300; Its synthesis step complexity, rare earth element cost is also than higher.US5,869,021 and US6,093,866 uses C ₂-C ₈Aliphatie diamine be template, in synthetic system, introduce rare earth element and can synthesize the ZSM-5/ZSM-11 eutectic zeolite that contains rare earth.This eutectic zeolite shows outstanding hydrothermal stability and contamination resistance in hydrocarbon conversion process.

Usually use tetrapropyl ammonium and TBuA to be template can lead the respectively MFI or the MEL molecular sieve of pure phase.Use Tetrabutyl amonium bromides such as (R. Chiappetta, R. Aiello, et, Zeolite. 18 (1997) 106 for F. Testa, R. Szostak) Jablonski are made template, by changing crystallization temperature (120-200 ⁰C) can control the crystalline phase of sample with the ratio of sodium oxide and potassium oxide.When the hydrothermal crystallizing temperature is lower, higher relatively potassium content helps forming the ZSM-11 of pure phase; Can obtain the ZSM-5/-11 eutectic when improving crystallization temperature and reducing potassium content.(G.?A.?Jablonski,?L.B.Sand,?Zeolite.?6?(1986)?396)。

People such as Patrick M.Piccione join silicon source Ludox AS-40 in the structure directing agent TBAH (TBAOH) and constantly stir, and add sodium hydroxide (NaOH) and form the mole composition: SiO2:0.06 TBAOH:0.12 NaOH:10.25 H ₂The reaction system of O, this system is 150 ⁰Crystallization is four days under the C, takes out suction filtration, washing, acetone is washed, drying obtains the ZSM-5/ZSM-11 duplex grain structure molecular sieve elliptical shape particle for about 5 m of size, does not significantly pile up.（P.?M.?Piccione,?M.?E.?Davis,?Microporous?Mesoporous?Mater.?49?(2001)?163）。

People such as Michell Sofia Francesconi are with 4-propyl bromide (TPABr, T ₁) and Tetrabutyl amonium bromide (TBABr, T ₂) be template, mole is formed: 100SiO ₂: xAl ₂O ₃: 10Na ₂O:30T:4200H ₂O, T ₁: T ₂=1:3,1:1,3:1, reaction system is 150 ⁰Crystallization obtained the MFI/MEL eutectic molecular sieve in 3 days under the C, and size of particles is 0.5-2 m.（M.?S.?Francesconi,?Z.?E.?Lopez,?et.?Catal.?Today.?107-108?(2005)?809）。

People such as Gema Gonzalez are template with the Tetrabutyl amonium bromide, are the aluminium source with aluminium hydroxide, and sodium hydroxide is the sodium source, and mole is formed: 100SiO ₂: xAl ₂O ₃: 10Na ₂O:30T:4200H ₂O, x=5,2,1,0.25, the particle that obtains when silica alumina ratio is 50 and 200 is the molecular sieve of MFI/MEL eutectic structure.This method template consumption is big, and system is rare, obtains the about 100 nm-3 m of particle.（G.?Gonzalez,?M.?E.?Gomes,?et.?Microporous?Mesoporous?Mater.?121?(2009)?26?）。

USP4,229,424 the report use quaternary ammonium salt or season phosphonium salt can synthesize the ZSM-5/ZSM-11 intermediate phase that the sodium type has fault as template, its unit cell dimension is at least greater than 4.0 nm.

Summary of the invention

The method that the purpose of this invention is to provide a kind of MFI/MEL of preparation eutectic molecular sieve, this method is simply effective, and is applied widely, can be at different synthetic systems.

Concrete technical scheme of the present invention is:

A kind of method for preparing the MFI/MEL eutectic molecular sieve, this method comprises following concrete steps:

⑴ the mode of, the synthetic MEL of the having structure molecular screen be familiar with according to the professional person mixes silicon source, organic formwork agent, water and other component by its mole proportioning;

⑵, in said mixture, add alcohol, in the reactor of packing into after stirring, 100～200 ℃ of following crystallization 10～200 hours, filter and drying after, obtain MFI/MEL eutectic structure molecular sieve; Wherein: alcohol is 0.5～5 with the silica molar ratios of molecular sieve mother liquor.

The silicon source is nine water water glass (Na among the described step ⑴ ₂SiO ₃9H ₂O), silicon sol, silica gel, alumino silica gel, positive quanmethyl silicate, positive tetraethyl orthosilicate (TEOS) or its mixture, preferred fresh precipitation silica gel or alumino silica gel, institute's synthesis of molecular sieve crystal grain is more even, the utilization ratio of silicon is high more.

Other component can comprise aluminium source, mineral alkali or its mixture among the described step ⑴, also can not comprise any of these component.

The aluminium source is inorganic aluminates such as Tai-Ace S 150 and aluminum nitrate or sodium metaaluminate, aluminum isopropylate aluminum contained compound among the described step ⑴.

Mineral alkali is sodium hydroxide, potassium hydroxide, ammoniacal liquor or its mixture among the described step ⑴.

Alcohol among the described step ⑵ is ethanol, propyl carbinol, the trimethyl carbinol, n-hexyl alcohol or its mixture, is preferably ethanol.

Template is TBAH (TBAOH), Tetrabutyl amonium bromide (TBABr) and composition thereof among the described step ⑴, or TBAH (TBAOH), Tetrabutyl amonium bromide (TBABr) synthetic guiding glue, more preferably TBAH (TBAOH).

. the present invention can form the MFI/MEL eutectic molecular sieve simply, effectively by the adding of small molecular alcohol.The present invention is applied widely, can be used for different synthetic systems; Employed small molecular alcohol is simple and easy to.

Description of drawings

Fig. 1 is the X ray collection of illustrative plates of Comparative Examples 1,2 synthetic MEL molecular sieves of the present invention, and the figure that insert in the upper left corner is the XRD figure of 44-47 ℃ of scope;

Fig. 2 is the X ray collection of illustrative plates of the embodiment of the

invention

1,2,3 synthetic eutectic structure molecular sieves, and the figure that insert in the upper left corner is the XRD figure of 44-47 ℃ of scope;

Fig. 3 is the X ray collection of illustrative plates of the embodiment of the invention 4,5,6 synthetic eutectic structure molecular sieves, and the figure that insert in the upper left corner is the XRD figure of 44-47 ℃ of scope;

Fig. 4 is the SEM figure of the embodiment of the invention 1,4,5,6 synthetic eutectic structure molecular sieves.

Embodiment

Describe the present invention in detail below by embodiment, but the present invention is not limited to this.

Comparative Examples 1

(1) 58.82 ml hydrochloric acid (3.4 mol/L) is splashed into 28.436 grams, nine water water glass (Na under constantly stirring ₂SiO ₃9H ₂O) in, continue to stir 2 hours, in reaction system, add water 70-80 ℃ of stirred in water bath 2 hours, wash suction filtration then and obtain filter cake, in above-mentioned filter cake, add 12.455 gram TBAH (TBAOH 25%) and 1.717 gram distilled water then, stirred 2 hours, and obtained reaction mixture;

(2) with above-mentioned reaction mixture 175 ℃ of following crystallization 3 days, the washing of cooling suction filtration obtains MEL-2 in 100 ℃ of following dryings.X-ray diffraction is measured the MEL-2 structure, finds that it is the ZSM-11 molecular sieve (the X ray collection of illustrative plates is shown in Fig. 1 (b)) with pure MEL structure.

Embodiment 1

Method according to Comparative Examples 1 prepares MFI/MEL-1, unique different be before crystallization, in reaction mixture, to add 4.605 gram ethanol (analytical pure) in addition, make pure silicon than x=1, obtain having the molecular sieve of MFI and MEL eutectic structure after 3 days 175 ℃ of following crystallization then.(the X ray collection of illustrative plates is shown in Fig. 2 (a), and sem photograph is shown in Fig. 4 (a)).

Embodiment 2

Method according to Comparative Examples 1 prepares MFI/MEL-2, unique different be before crystallization, in reaction mixture, to add 9.214 gram ethanol (analytical pure) in addition, make pure silicon compare x=2, obtain having the molecular sieve of MFI and MEL eutectic structure after 3 days 175 ℃ of following crystallization then, (the X ray collection of illustrative plates is shown in Fig. 2 (b)).

Embodiment 3

Method according to Comparative Examples 1 prepares MFI/MEL-3, unique different be before crystallization, in reaction mixture, to add 18.428 gram ethanol (analytical pure) in addition, make pure silicon compare x=4, obtain having the molecular sieve of MFI and MEL eutectic structure after 3 days 175 ℃ of following crystallization then, (the X ray collection of illustrative plates is shown in Fig. 2 (c)).

Embodiment 4

Method according to Comparative Examples 1 prepares MFI/MEL-4, unique different be before crystallization, in reaction mixture, to add 7.414 gram propyl carbinols (analytical pure) in addition, alcohol silicon compares x=1, had the molecular sieve of MFI and MEL eutectic structure after 3 days jointly 175 ℃ of following crystallization then, (the X ray collection of illustrative plates is shown in Fig. 3 (a), and sem photograph is shown in Fig. 4 (b)).

Embodiment 5

Method according to Comparative Examples 1 prepares MFI/MEL-5, unique different be before crystallization, in reaction mixture, to add the 7.438 gram trimethyl carbinols (analytical pure) in addition, alcohol silicon compares x=1, had the molecular sieve of MFI and MEL eutectic structure after 3 days jointly 175 ℃ of following crystallization then, (the X ray collection of illustrative plates is shown in Fig. 3 (b), and sem photograph is shown in Fig. 4 (c)).

Embodiment 6

Method according to Comparative Examples 1 prepares MFI/MEL-6, unique different be before crystallization, in reaction mixture, to add 10.223 gram n-hexyl alcohols (analytical pure) in addition, alcohol silicon is had the molecular sieve of MFI and MEL eutectic structure 175 ℃ of following crystallization then jointly than x=1 after 3 days.(the X ray collection of illustrative plates is shown in Fig. 3 (c), and sem photograph is shown in Fig. 4 (d)).

Comparative Examples 2

With 0.101 sodium metaaluminate (52, wt% Al ₂O ₃, 40, wt% NaO2) be dissolved in 12.455 gram TBAH (TBAOH 25 Wt%) and 12.259 gram distilled water, add 6.417 gram Qingdao silica gel (SiO ₂93.5 Wt %), obtain reaction mixture after mixing, 150 ℃ of following crystallization 5 days, the washing of cooling suction filtration obtained MEL-1 in 100 ℃ of following dryings.X-ray diffraction is measured the MEL-1 structure, finds that it is the ZSM-11 molecular sieve (the X ray collection of illustrative plates is shown in Fig. 1 (a)) with pure MEL structure.

Embodiment 7

Method according to Comparative Examples 2 prepares MFI/MEL-7, unique different be before crystallization, in reaction mixture, to add 4.605 gram ethanol (analytical pure) in addition, make pure silicon than x=1, had the aluminium containing molecular sieve of MFI and MEL eutectic structure 150 ℃ of following crystallization after 5 days jointly.

Claims

1. method for preparing the MFI/MEL eutectic molecular sieve is characterized in that this method comprises following concrete steps:

, according to known synthetic prescription with MEL structure molecular screen, with silicon source, template, water and other component thorough mixing, make synthetic mixture;

⑵, in above-mentioned synthetic mixture, add alcohol, in the reactor of packing into after stirring, 100～200 ℃ of following crystallization 10～200 hours, filter and drying after, obtain MFI-MEL eutectic structure molecular sieve; Wherein: alcohol is 0.5～5 with the silica molar ratios of molecular sieve mother liquor; Described alcohol is: ethanol, propyl carbinol, the trimethyl carbinol, n-hexyl alcohol or its mixture.