CN102530981B

CN102530981B - Method for synthesizing mobil composition of matters-41(MCM-41) mesoporous molecular sieve

Info

Publication number: CN102530981B
Application number: CN 201210037997
Authority: CN
Inventors: 张坤; 罗琛; 袁恩辉; 薛青松; 徐浪浪; 侯琼玮; 吴鹏
Original assignee: East China Normal University
Current assignee: East China Normal University
Priority date: 2012-02-20
Filing date: 2012-02-20
Publication date: 2013-10-30
Anticipated expiration: 2032-02-20
Also published as: CN102530981A

Abstract

The invention relates to a method for synthesizing a mobil composition of matters-41(MCM-41) mesoporous molecular sieve. The method comprises the following steps of: dissolving SiO2 filter cakes obtained by recovering MCM-48 synthetic mother liquor in an alkali solution, and stirring at constant temperature of 60 DEG C for 1 hour; dripping the solution into an aqueous solution containing a surfactant, stirring at the constant temperature of 60 DEG C for 2 hours, cooling to the room temperature, transferring the mixture to a closed reactor, and crystallizing at the temperature of between 80 and 130 DEG C for 15 to 24 hours; and filtering, washing and drying a crystallized product to obtain the MCM-41 mesoporous molecular sieve, wherein a molar ratio of SiO2 to cetyltrimethylammonium tosylate (CTATos) to NaOH or KOH to H2O in the MCM-41 mesoporous molecular sieve is 1:(0.015-0.06):(0.15-0.35):(40-200). Compared with the prior art, the method has the obvious advantages that: a silicon source which is left in the synthetic mother liquor of a mesoporous material can be recycled, the using amount of the surfactant is low, the utilization rate of the silicon source is high, and the quality and purity of products are high; and in addition, and the method is short in synthetic period, low in cost and high in repeatability, the products are easy to synthesize on a large scale, so the method is an environment-friendly synthetic process.

Description

A kind of synthetic method of MCM-41 mesopore molecular sieve

Technical field

The present invention relates to a kind of preparation method of mesopore molecular sieve, specifically the preparation method of high hydrothermal stability silicon-based mesoporous molecular sieve MCM-41 under a kind of very low cost.

Background technology

Ordered mesoporous material refers to the mesoporous material of duct rule and ordered arrangement, synthetic work as far back as mesoporous material in 1971 just begins, the Kuroda of Japan also transformed the beginning mesoporous material by layered silicate in the presence of tensio-active agent before 1990 synthetic, the report of Mobil in 1992 just causes people's extensive attention, and is considered to synthetic really the beginning of mesoporous material.Mobil uses tensio-active agent as template, has synthesized M41S series mesoporous material, comprises MCM-41(six side's phases), the MCM-48(Emission in Cubic) and the MCM-50(laminate structure).Because this material has regular pore passage structure, larger specific surface area (～1000m ²/ g) and pore volume (～1.0ml/g) and aperture size that can modulation (2.0～50nm) have caused at catalysis, absorption and separation field and to have studied widely interest.

The research work of recent two decades mesoporous material development is exceedingly fast, and achieves noticeable achievement, and relates to all respects (Chem. Rev., 2007,107,2821.) such as synthetic, structure, character, application.But large-scale industrialization is used also and is not realized, the problem that awaits solving is a lot, and synthetic greenization and very low cost are exactly one of them.Use more cheap silicon source, replace the synthetic cost that the synthetic MCM-41 of expensive, poisonous TEOS can greatly reduce mesoporous material such as water glass, the silica gel of being fuming, alkaline silica sol.But in the middle of the preparation process, cats product cetyl trimethylammonium bromide (CTABr) consumption is very big, usually the mol ratio (Chem. Mater., 1996,8,1147.) between 0.15-0.65 of tensio-active agent/silicon.A large amount of uses of tensio-active agent, increased on the one hand the synthetic cost of mesoporous material, a large amount of foams that produce in the last handling process on the other hand are unfavorable for product separation and washing, simultaneously also environment is caused great pollution, therefore limited the scale operation of MCM-41.MCM-48 has three-dimensional continuous pore passage structure, with respect to the MCM-41 mesoporous material of one-dimensional channels, has larger advantage and application prospect aspect molecular diffusion.But because the synthetic phase region of MCM-48 is relatively narrow, synthesis condition is extremely harsh, and the synthetic basicity that need to be higher of common MCM-48, cause the yield of product very low, synthetic cost is improved, greatly limit range of application (the Chem. Mater. of MCM-48,1994,6,2317; Chinese patent: CN1188689A and CN1775673A; Chem. Mater., 1996,8,1147.).From above-mentioned report as seen, the synthetic method condition of existing mesoporous material is extremely harsh, cost is high, pollution is large, is unfavorable for the suitability for industrialized production of mesoporous material.

Recently, bibliographical information a kind of new synthesis strategy utilize cetyl trimethylammonium bromide salt to be the positively charged ion template, than low surfactant concentration and fluorion (F ^-) exist down, synthesized the MCM-48 mesoporous material (Micropor. Mesopor. Mater., 2005,86,314) of high quality, high hydrothermal stability.The plurality of advantages such as synthetic method is simple although this material has, easily repetition, the easy recovery of product, because synthetic system basicity is higher, the utilization ratio in silicon source lower (loss of 70% silicon species) causes the synthesis yield of MCM-48 to reduce.In addition, in mesoporous material large-scale production process (2L reactor), contain the direct discharging of silicon species and fluorium ion liquid, be easy to cause environmental pollution.

Summary of the invention

The object of the present invention is to provide a kind of fast, the preparation method of the MCM-41 mesopore molecular sieve of simple, low-cost, mass-producing; it is the silicon source that the method is reused silicon species residual in the MCM-48 synthesis mother liquid; take cetyl trimethyl p-methyl benzenesulfonic acid ammonium salt (CTATos) as template molecule, the synthetic MCM-41 mesoporous material of low-cost and high-quality.

The object of the present invention is achieved like this:

The synthetic method of MCM-41 mesopore molecular sieve under a kind of very low cost, the method in the MCM-48 synthesis mother liquid residual silicon species (silicon species is by the salt acidometric titration as the silicon source, reclaim in the mode of suction filtration and to obtain), cetyl trimethyl p-methyl benzenesulfonic acid ammonium salt (CTATos) as cats product, sodium hydroxide or potassium hydroxide as alkali source, its concrete steps are: according to the synthetic MCM-48 mesoporous material of the method for bibliographical information, the mother liquor that obtains after filtering, concentrated hydrochloric acid titration deposition, the filter cake that obtains is as the synthetic silicon source of MCM-41 mesoporous material.This silicon source is dissolved into 60 ℃ of constant temperature stirred 1 hour in the middle of the aqueous solution that contains alkali, then this solution is dropwise joined in the middle of the aqueous solution that contains cetyl trimethyl p-methyl benzenesulfonic acid ammonium salt tensio-active agent, 60 ℃ of constant temperature continue to stir 2 hours, be cooled to and be transferred to after the room temperature in the closed reactor 80～150 ℃ of crystallization 15～24 hours, at last with crystallization product after filtration, after the washing, drying, 550～1000 ℃ of lower roastings 3～6 hours, obtain the MCM-41 molecular sieve; Wherein: the mol ratio of described material is: SiO2:CTATos:NaOH/KOH:H2O=1:0.015～0.06:0.15～0.35:40～200.Wherein: employed cetyl trimethyl toluenesulfonate (CTATos) cats product comes from the Merck chemical reagents corporation of Germany; The silicon source is silicon species residual in the MCM-48 synthesis mother liquid, and silicon species is by the salt acidometric titration, reclaims acquisition in the mode of suction filtration; Alkali source is commercially available sodium hydroxide or potassium hydroxide.

The present invention compared with prior art has following advantage:

⑴ the recycling in silicon source in, the MCM-48 synthesis mother liquid can reduce the synthetic cost of current MCM-48 mesoporous material on the one hand; On the other hand, the salt acidometric titration obtains silicon species and can directly as the synthetic initial silicon source of MCM-41 mesoporous material, reduce the direct discharging pollution on the environment of MCM-48 synthesis mother liquid.

⑵, in MCM-41 is synthetic, use cetyl trimethyl p-methyl benzenesulfonic acid ammonium salt as template, can greatly reduce the consumption of tensio-active agent, synthesize cost thereby reduce, reduced environmental pollution.Tensio-active agent cetyl trimethyl p-methyl benzenesulfonic acid ammonium salt in the of paramount importance because system is by 100% utilization, filter, in the washing process without any foam produce, simplified sample reclaimer operation step; In addition, the synthetic basicity of current MCM-41 can control extremely low (the synthetic phasor of MCM-41 is wider), do not have the problem that silicon species runs off in the MCM-48 building-up process, the utilization ratio in silicon source is near 100%.Therefore the synthetic method of current report can realize the large-scale production of mesoporous material (MCM-48 and MCM-41).

, from the characterization result of product, the product aperture homogeneous that the present invention obtains, hydrothermal stability are high.Sample was 600 ℃ of roastings 6 hours, and surface-area reaches 1080m ²/ g, pore volume are 0.96ml/g, and the aperture is the 3.4nm(BJH method of calculation).

⑷ the production peak of the single still MCM-41 of, 2L mesopore molecular sieve is 0.2Kg, can realize the large-scale industrial production of mesoporous material under the prerequisite that guarantees product purity, quality, economic benefit and ecological benefits.

Description of drawings

Fig. 1 is the XRD figure spectrum of MCM-41 mesopore molecular sieve under different maturing temperatures that the present invention prepares;

Fig. 2 is scanning electron microscope (SEM) figure of the MCM-41 mesopore molecular sieve for preparing of the present invention;

Fig. 3 is high-resolution-ration transmission electric-lens (TEM) figure of the MCM-41 mesopore molecular sieve for preparing of the present invention.

Embodiment

The invention will be further described below by embodiment, and its purpose only is better to understand research contents of the present invention and unrestricted protection scope of the present invention.

Embodiment 1

The preparation in the synthetic silicon source of MCM-41 mesoporous material: reference literature (Micropor. Mesopor. Mater., 2005,86,314) the synthetic high-quality MCM-48 mesopore molecular sieve of the method for report, is dried to get the MCM-48 mesopore molecular sieve at products therefrom suction filtration, washing.The mother liquor that the first time, suction filtration obtained keeps, and then 37% concentrated hydrochloric acid titration gets white depositions, the SiO that filtration washing obtains ₂Filter cake is directly as the synthetic silicon source of MCM-41 mesoporous material.

Synthesizing of MCM-41 mesoporous material: 8.0g NaOH is joined in the beaker that contains the 720ml deionized water, then add the SiO that 60.0g is obtained through acidometric titration by the MCM-48 mother liquor ₂Filter cake stirred 1 hour at 60 ℃ of constant temperature, obtained solution A; 32.8g cetyl trimethyl toluenesulfonate (CTATos) is joined in the beaker that contains the 720ml deionized water, and 60 ℃ of constant temperature stir 1 hour to the solution becomes clarification, obtain solution B; Solution A is dropwise joined in the solution B, and 60 ℃ of constant temperature stirred 2 hours, obtained white precipitate, and the mole of this mixture consists of SiO ₂/ CTATos/NaOH/H ₂O=1:0.05:0.20:80; After this mixture is cooled to room temperature, be transferred in the 2L reactor 100 ℃ of crystallization 20 hours, products therefrom suction filtration, washing, dry to get the MCM-41 mesopore molecular sieve.

Gained MCM-41 mesopore molecular sieve heat stability testing: in respectively roasting 4 hours of 600 ℃, 900 ℃ and 1000 ℃, pore structure remains intact the former powder that suction filtration, washing and oven dry are obtained respectively.The XRD of sample, SEM and TEM characterize and see accompanying drawing.

Embodiment 2

Potassium hydroxide prepares high-quality MCM-41 mesopore molecular sieve as alkali source:

Except the sodium hydroxide that replaces with potassium hydroxide among the embodiment 1, other preparation condition is all identical with embodiment 1.

Embodiment 3

Improve crystallization temperature and prolong crystallization time and prepare high-quality MCM-41 mesopore molecular sieve:

Keep the mole of mixture to form SiO ₂/ CTATos/NaOH/H ₂O=1:0.05:0.20:80 is constant, and crystallization temperature is 130 ℃, crystallization time 24 hours, and other preparation condition is all identical with embodiment 1 with process.

Embodiment 4

The consumption that reduces water prepares high-quality MCM-41 mesopore molecular sieve:

Keeping crystallization temperature is that 130 ℃ and crystallization time 24 hours are constant, and the mole that changes mixture forms SiO ₂/ CTATos/NaOH/H ₂O=1:0.05:0.20:40, other preparation condition is all identical with embodiment 1 with process.

Claims

1. the synthetic method of a MCM-41 mesopore molecular sieve is characterized in that the method comprises following concrete steps:

A, synthetic MCM-48 mesoporous material according to known technique reclaim the mother liquor after filtering, and obtain white opacity through 37% salt acidometric titration, and the filter cake that suction filtration obtains is as the silicon source;

B, the silicon source of step a is dissolved in sodium hydroxide or the potassium hydroxide solution, 60 ℃ of constant temperature stirred 1 hour, then this solution is joined dropwise that to contain cetyl trimethyl p-methyl benzenesulfonic acid ammonium salt be in the aqueous solution of CTATos, 60 ℃ of constant temperature continue to stir 2 hours, be transferred in the closed reactor after being cooled to room temperature, 80～150 ℃ of crystallization 15～24 hours, crystallization product after filtration, after the washing, drying, 550～1000 ℃ of lower roastings 3～6 hours, obtain the MCM-41 mesopore molecular sieve;

Wherein: the mol ratio of described material is: SiO ₂: CTATos:NaOH/KOH:H ₂O=1:0.015～0.06:0.15～0.35:40～200.