CN1208248C - Preparation method of mesopore aluminium containing molecular sieve - Google Patents

Abstract

The present invention discloses a method for preparing a mesoporous molecular sieve containing aluminium. In the method, firstly, a silicon source and an aluminum source are hydrolyzed, mixed and heated to more than 40 DEG C for 0.25 hour to 5 days; then the heated mixture is added into an acidic solution of surface active agents, and the mixture is maintianed for 0.5 hour to 24 hours; finally, products are separated and roasted. With the method, precursors with high quality and effectivity can be obtained, and in the prepared mesoporous molecular sieves, aluminum fully enters frameworks.

Description

A kind of preparation method of mesopore aluminium containing molecular sieve

Technical field the invention relates to a kind of preparation method of mesoporous molecular sieve, further says so about a kind of preparation method of aluminiferous MCM-41 molecular sieve.

Background technology MCM-41 is a member of the mesoporous molecular sieve M41S family of U.S. Mobil company reported first in 1992, has regular one dimension sexangle central hole structure.Because its homogeneous granules degree and consistent middle hole shape, people have given increasing concern to it.

USP5108725 discloses the preparation method of MCM-41, is to descend about two day time hydro-thermal synthetic in 100 ℃～150 ℃ by alumino silica gel or silica gel in the basic solution of quaternary amine alkali (salt) tensio-active agent.

Nature, 1994, Vol368, P317 have reported a kind of diverse route, in the acidic solution of tensio-active agent, be the silicon source with tetraethoxy-silicane and water glass, at room temperature promptly, only need 30 minutes～2 hours, can synthesize the M41 molecular sieve, this route is referred to as S ⁺X ^-I ⁺Route.

Characterization of Porous solid IV 1997, the p81 report is catalyzer hydrolysis tetraethoxy-silicane in alkaline system with ammonia, room temperature synthesized MCM-41 in following about 1 hour.Undoubtedly, both compare the back with the former, and are more simple and easy to do.

Mat.Re s.Soc.Symp.Proc., Vol454 is in P113～117, people such as A.Karllson adopt different aluminium source (Tai-Ace S 150, aluminum isopropoxide, aluminum ethoxide), different reinforced order, and different generated times, attempt Al is inserted among the MCM-41, all fail.

At document Microporous and Mesoporous Materials, 32,1999, in P55～62, people such as A.Matsumato are silicon source and aluminium source with tetraethoxy-silicane and aluminium isopropoxide, are catalyzer with ammonia, in alkaline system, synthesized Al-MCM-41, the deficiency of this method is that one side has adopted expensive organosilicon source and organoaluminum source, is all to exist non-framework aluminum in the molecular sieve on the other hand in the product.

Up to now, do not see employing S ⁺X ^-I ⁺Route synthesizes the report of Al-MCM-41.

Summary of the invention

The object of the present invention is to provide a kind of with S ⁺X ^-I ⁺Route synthesizes the Al-MCM-41 molecular sieve that does not contain non-framework aluminum.

The preparation method of Al-MCM-41 provided by the present invention is made up of the following step:

(1) with silicon source and hydrolysis of aluminium source and mixing, be heated to more than 40 ℃, preferred 60～180 ℃, kept 0.25 hour～5 days, preferred 2～24 hours, get system A, wherein, the silicon source is organosilicon source or inorganic silicon source, the aluminium source is inorganic aluminium source or organoaluminum source, SiO ₂/ Al ₂O ₃Mol ratio is 10～100, preferred 30～90;

(2) with surfactant dissolves in a kind of acidic solution, obtain the system B of pH＜4.0, preferred pH＜2.0, wherein the add-on of said tensio-active agent be with SiO ₂The silicon source mol ratio of expression is 0.1～0.9;

(3) A is added among the B, kept 0.5 hour～24 hours, preferred 1～12 hour;

(4) isolate product and carry out roasting.

In the method provided by the present invention, the said preferred inorganic silicon in silicon source that gets of step (1), said inorganic silicon source is selected from water glass, Starso and various forms of soft silica; The organosilicon source is alkyl silicon or alkoxyl silicone.

Said aluminium source is selected from inorganic aluminium source or organoaluminum source, preferred inorganic aluminium source.Inorganic aluminium source is selected from sodium aluminate, sodium metaaluminate, Tai-Ace S 150, aluminum chloride, aluminium hydroxide, and said organoaluminum source is selected from aluminum alkyls or aluminum alkoxide.

Source hydrolysis of said aluminium and blended process can also can be mixed them earlier, aluminium source and silicon source difference hydrolysis earlier remix again with the mixture hydrolysis.

The said tensio-active agent of the present invention is meant that can guide final product forms the material with M41S family structure, can be that a kind of material also can be the mixture of several materials, for example has general formula C _nH _2n+1(CH ₃) ₃NX (X=Br, Cl, OH, NO ₃) material, wherein n preferred 12～22.

Said acidic solution is inorganic acid solution and/or organic acid soln.Said mineral acid is selected from one of hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid or Hydrogen bromide or their mixture, and other shows the mixture of tart material or above-mentioned substance in water; Said organic acid is meant the organism with RCOOH general formula, and wherein R is the alkyl that contains 1～6 carbon atom.

Said B can adopt once or be divided into repeatedly and adding among the C.

Said separation can be adopted and filter or the mode of centrifugation, and said aftertreatment comprises washing, drying and roasting, and said maturing temperature is 400～750 ℃, preferred 500 ℃～650 ℃.

The preparation method of MCM-41 provided by the invention has following characteristics:

(1), make Al in the aluminium source and the Si in the silicon source can be combined into Al-O-Si, from liquid owing to adopted with silicon-aluminum sol mixture intensification aged mode ²⁷Al NMR composes (Fig. 4) as can be seen, and single casual peak explanation forms (SiO-) near chemical shift 57 ₄The structure of Al, this point are the obvious differences (Fig. 1) with prior art, thereby have obtained high quality, effective precursor;

(2) solid ²⁷In the Al NMR spectrum, it is unimodal that chemical shift 57 places occur is the characteristic peak of framework aluminum, and Fig. 5 shows and do not have non-framework aluminum in the product that Al all enters skeleton.

Description of drawings

Fig. 1 is the liquid of alumino silica gel liquid solution in the Comparative Examples ²⁷Al NMR spectrum.

Fig. 2 is the X-ray diffraction spectrogram of MCM-41 molecular sieve.

Fig. 3 is the solid of the prepared MCM-41 molecular sieve of Comparative Examples ²⁷Al NMR spectrum.

Fig. 4 is the liquid of alumino silica gel liquid solution among the embodiment 1 ²⁷Al NMR spectrum.

Fig. 5 is the solid of the prepared MCM-41 molecular sieve of embodiment 1 ²⁷Al NMR spectrum.

Embodiment

Following examples will the invention will be further described, but scope not thereby limiting the invention.

Comparative Examples

Na with 123 grams, 35 heavy % ₂SiO ₃9H ₂The Al of O (Beijing chemical reagents corporation, analytical pure) solution and 22.0 grams, 9.1 heavy % ₂(SO ₄) ₃18H ₂O (South Platform China prosperous chemical industry company limited, analytical pure) solution mixes, and places a week down, obtains liquid mixture A, its for 25 ℃ ²⁷Al NMR spectrum is seen Fig. 1,71,65 and 61 3 chemical shift peaks as can be seen from Figure 1, show that at the peak of chemical shift 71 a same silicon-oxy tetrahedron of aluminum-oxygen tetrahedron is in conjunction with the structure that abbreviates Q1 as, the peak of chemical shift 65 shows an aluminum-oxygen tetrahedron, and two silicon-oxy tetrahedrons are in conjunction with the structure that abbreviates Q2 as together, and the peak at chemical shift 61 places shows that an aluminum-oxygen tetrahedron abbreviates the structure of Q3 as with three silicon-oxy tetrahedrons combinations; And there is not chemical shift in Fig. 1 is 57 peak, this peak corresponding to an aluminum-oxygen tetrahedron with four silicon-oxy tetrahedrons in conjunction with the structure that abbreviates Q4 as, the Q4 structure is the best basic structural unit of synthesis of molecular sieve, can prevent the generation of non-framework aluminum effectively.

The Hydrogen bromides of 424 grams, 28 heavy % are warming up to 40～50 ℃, add cetyl trimethylammonium bromides (Beijing chemical reagents corporation, the analytical pure) dissolving of 8.3 grams after, stirred 15 minutes, obtain solution B.

Solution A is added in the solution B, stirred 1 hour, filter, to pH=6～7, drying is 4 hours under 80 ℃, then 560 ℃ of following roastings 8 hours, obtains white products with deionized water wash, and ultimate analysis shows SiO ₂/ Al ₂O ₃=62, its X-ray diffraction spectrogram illustrates that this product has the MCM-41 structure as shown in Figure 2; Its solid ²⁷Al NMR spectrum as shown in Figure 3, as can be seen from Figure 3, near the spectrum peak chemical shift 0 is the peak of hexa-coordinate aluminium outside the skeleton, characteristic peak then appears in framework aluminum about 57, be non-framework aluminum from scheming to have as can be seen 75.95% aluminium.

Embodiment 1

Na with 123 grams, 35 heavy % ₂SiO ₃9H ₂The Al of O solution and 22.0 grams, 9.1 heavy % ₂(SO ₄) ₃18H ₂O solution mixes, and obtains solution A, is warming up to 80 ℃, keeps 6 hours, the liquid of the mixture of the aging back gained that heats up ²⁷Al NMR spectrogram as shown in Figure 4, comparison diagram 1, as can be seen, after process heated up and wears out, chemical transformation had taken place in colloidal solution, Al and Si are in conjunction with having formed the Si-O-Al bridged bond, near chemical shift 57 single casual peaks have appearred in the peak that does not occur Q1, Q2 and Q3 structure among Fig. 4, and this peak abbreviates the structure of Q4 as with four silicon-oxy tetrahedrons combinations corresponding to an aluminum-oxygen tetrahedron, the Q4 structure is the best basic structural unit of synthesis of molecular sieve, can prevent the generation of non-framework aluminum effectively.

The Hydrogen bromides of 424 grams, 28 heavy % are warming up to 40～50 ℃, add the cetyl trimethylammonium bromides dissolving of 18.3 grams after, stirred 15 minutes, obtain solution B, its pH=1.2;

Solution A is added in the solution B, stirred 1 hour, filter, to pH=6～7, drying is 4 hours under 80 ℃, then 560 ℃ of following roastings 8 hours, obtains white products with deionized water wash.Ultimate analysis shows its SiO ₂/ Al ₂O ₃=62; Its X-ray diffraction spectrogram has the feature of Fig. 2, and the structure with MCM-41 is described.Solid ²⁷Al NMR spectrogram as shown in Figure 5, having only a chemical shift among this figure is 57 peak, this peak ownership framework aluminum illustrates that aluminium in institute's synthetic molecular sieve all on skeleton, does not have non-framework aluminum.

Embodiment 2

1.25 gram aluminium isopropoxide (Beijing chemical reagents corporation) is dissolved in 50 gram tetraethoxy-silicanes (Beijing chemical reagents corporation), and hydrolysis in the NaOH of 90 milliliters of 2.0M solution, hydrolyzed solution is warmed up to 100 ℃ kept the liquid that obtains 10 hours ²⁷Al NMR spectrum has the feature of Fig. 4.

The cetyl trimethylammonium bromide of 13.2 grams is dissolved in the hydrobromic acid solution of 670 grams, 25 weight %, above-mentioned sial solution is added wherein, stirred 1.5 hours, filter, to pH=6～7, drying is 4 hours under 80 ℃ with deionized water wash, then 560 ℃ of following roastings 8 hours, get white products,, illustrate that product is SiO through ultimate analysis and XRD spectra analysis ₂/ Al ₂O ₃=87 MCM-41 molecular sieve, its solid ²⁷Al NMR spectrum has the identical feature of Fig. 5, at chemical shift 57 places unique spectrum peak is arranged, and illustrates that aluminium in institute's synthetic molecular sieve all on skeleton, does not have non-framework aluminum.

Embodiment 3

The 2 gram aluminium isopropoxides (Beijing chemical reagents corporation, analytical pure) and the solution of 5mL Virahol preparation are splashed into the Na of 123 grams, 35 heavy % ₂SiO ₃9H ₂O (Beijing chemical reagents corporation, analytical pure) in the solution, obtain solution A, be warming up to 80 ℃, kept 6 hours, the liquid 27AlNMR spectrogram of the mixture of the aging back of intensification gained as shown in Figure 4, comparison diagram 1, as can be seen, through single 57.653 casual peaks having occurred in the aging back spectrogram that heats up, illustrate that chemical transformation has taken place colloidal solution, Al and Si are in conjunction with having formed (SiO-) ₄The Al structure.

The Hydrogen bromides of 424 grams, 28 heavy % are warming up to 40～50 ℃, add cetyl trimethylammonium bromides (Beijing chemical reagents corporation, the analytical pure) dissolving of 45 grams after, stirred 15 minutes, obtain solution B;

Solution A is added in the solution B, stirred 1 hour, filter, to pH=6～7, drying is 4 hours under 80 ℃, then 560 ℃ of following roastings 8 hours, obtains white products with deionized water wash, and ultimate analysis shows, its SiO ₂/ Al ₂O ₃=41.Its X-ray diffraction spectrogram has the feature of Fig. 2, illustrates that it has the structure of MCM-41.Solid ²⁷Al NMR spectrogram as shown in Figure 5, having only a chemical shift among this figure is 57 peak, this peak ownership framework aluminum illustrates that aluminium in institute's synthetic molecular sieve all on skeleton, does not have non-framework aluminum.

Embodiment 4

All the other are identical with embodiment 1, and just the aluminium source is 0.44 gram aluminum chloride (AlCl ₃), the add-on of cetyl trimethylammonium bromide is 23 grams.Products obtained therefrom is a white powder, and XRD characterizes has the feature of Fig. 2, illustrates that what obtain is the MCM-41 molecular sieve, its ²⁷Al NMR spectrum only has one unimodally near chemical shift 57 as shown in Figure 5, shows aluminium all on skeleton, by ultimate analysis, and SiO ₂/ Al ₂O ₃=98.

Claims (3)

1, a kind of preparation method of mesopore aluminium containing molecular sieve is characterized in that this method is made up of the following step:

(1) with silicon source and hydrolysis of aluminium source and mixing, be heated to 40 ℃～180 ℃, kept 0.25 hour～5 days, get system A, wherein, the silicon source is selected from water glass, Starso, soft silica or tetraethoxy-silicane, and the aluminium source is selected from sodium aluminate, sodium metaaluminate, Tai-Ace S 150, aluminum chloride, aluminium hydroxide or aluminium isopropoxide, SiO ₂/ Al ₂O ₃Mol ratio is 10～100;

(2) with surfactant dissolves in a kind of acidic solution, obtain the system B of pH＜4.0, said tensio-active agent is for having general formula C _nH _2n+1(CH ₃) ₃The material of NX, n=12～22 wherein, X is selected from Br, Cl, OH or NO ₃, the add-on of tensio-active agent be with SiO ₂The silicon source mol ratio of expression is 0.1～0.9; Said acidic solution is selected from the organic acid that hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, Hydrogen bromide or general formula are RCOOH, and wherein R is the alkyl with 1～6 carbon atom;

(3) A is added among the B, kept 0.5 hour～24 hours;

(4) isolate product and carry out roasting.

2, in accordance with the method for claim 1, it is characterized in that the adding temperature range described in the step (1) is 60～180 ℃, described holding time is 2～24 hours, described SiO ₂/ Al ₂O ₃Mol ratio is 30～90; PH value scope described in the step (2) is pH＜2.0; Hold-time described in the step (3) is 1～12 hour.

3, in accordance with the method for claim 1, step (1) said silicon source and the hydrolysis of aluminium source and blended process are with aluminium source and silicon source difference hydrolysis earlier remix, perhaps they are mixed earlier, again with the mixture hydrolysis.

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