阅读说明：本技术 一种含钛高硅铝比丝光沸石的制备方法 (Method for preparing titanium-containing mordenite with high silicon-aluminum ratio ) 是由 庄大为 张媛 项天宇 于 2019-11-06 设计创作，主要内容包括：本发明提供了一种含钛高硅铝比丝光沸石的制备方法,本发明提供了一种含钛高硅铝比丝光沸石的制备方法,将氢型丝光沸石进行改性,获得含钛的、高硅铝比的丝光沸石。本发明通过改性将钛引入丝光沸石分子筛骨架中的同时提高分子筛的硅铝比,所得的含钛高硅铝比丝光沸石结晶度和纯度高,便于大规模工业生产。(The invention provides a method for preparing titanium-containing mordenite with high silica-alumina ratio, which is to modify hydrogen-type mordenite to obtain the titanium-containing mordenite with high silica-alumina ratio. The invention introduces titanium into the mordenite molecular sieve framework through modification and simultaneously improves the silicon-aluminum ratio of the molecular sieve, and the obtained mordenite with high titanium-containing silicon-aluminum ratio has high crystallinity and purity, thereby being convenient for large-scale industrial production.)

1. A method for preparing mordenite with titanium and high silicon-aluminum ratio is characterized in that the mordenite with titanium and high silicon-aluminum ratio is prepared by the following steps:

s1: dissolving a titanium source and oxalic acid in a solvent to prepare a modified solution;

s2: adding hydrogen mordenite into the modified liquid, and stirring to be uniform to obtain a modified liquid cement;

s3: placing the glue solution obtained in the step S2 into a reaction kettle, stirring and heating, slowly adding water into the reaction kettle while stirring, and continuing the reaction after the water is added until the modified mordenite glue solution is obtained;

s4: and (4) cleaning the modified mordenite glue solution obtained in the step (S3) to be neutral, drying by hot air, and then calcining to obtain the titanium modified mordenite with the high silica-alumina ratio.

2. The method of claim 1, wherein: in the step S1, the titanium source is one of fluotitanic acid, titanium tetrachloride, isopropyl titanate, and titanium isooctanolate, and the titanium content in the titanium source is 0.1 to 1kg in terms of equivalent of TiO 2.

3. The method of claim 1, wherein: in the step S1, the amount of oxalic acid is 10-50 kg.

4. The method of claim 1, wherein: in the step S1, the solvent is one or more of methanol, ethanol, tert-butyl alcohol, ethylene glycol, acetonitrile, toluene and ethyl acetate, the total amount of the solvent is 20-80kg, and the amount of the added hydrogen-type mordenite is 5-15 kg.

5. The method according to claim 1 or 4, characterized in that: in step S1, the total amount of solvent was 50kg, and the amount of hydrogen mordenite added was 10 kg.

6. The method of claim 1, wherein: in the step S2, the particle size of the hydrogen-type mordenite is 50-1000nm, and the silicon-aluminum ratio is 5-10.

7. The method of claim 1, wherein: in the step S3, the heating temperature is 100-180 ℃, the reaction time is 12-48h, the water addition amount is 0.1-5kg, and the water addition rate is 0.01-0.1 kg/h.

8. The method according to claim 1 or 7, characterized in that: in the step S3, the reaction time is 24h, and the water adding rate is 0.05 kg/h.

9. The method of claim 1, wherein: in the step S4, the calcining temperature is 550 ℃ and the calcining time is 4 h.

Technical Field

The invention belongs to the technical field of catalyst synthesis modification, and particularly relates to a preparation method of titanium-containing mordenite with a high silica-alumina ratio.

Background

Mordenite (MOR) is a molecular sieve with a twelve-ring super cage structure, and the mordenite molecular sieve shows excellent catalytic performance in reactions such as hydrocarbon cracking, hydrocracking, alkane isomerization, polycyclic aromatic compound alkylation and the like.

Titanium silicalite can be formed by incorporating the transition metal titanium into the molecular sieve framework. Because the titanium atom has a four-coordination structure, the titanium silicon mordenite has good high-selectivity catalytic activity for oxidation-reduction reaction and has excellent catalytic activity for ketoximation, epoxidation and other reactions. Compared with the titanium-silicon molecular sieves such as TS-1, Ti-MWW and the like, the synthesis of the titanium-silicon mordenite molecular sieve does not need an organic template agent, so that the titanium-silicon mordenite molecular sieve has lower production cost and good application prospect.

However, the use of titanium silicalite molecular sieves has presented a number of difficulties. For example, the formation of titanium tetrahedral structures on the silicon framework of mordenite is difficult, and the presence of aluminum atoms contained in the mordenite molecular sieve poisons the titanium active site, and the like. In contrast, effective means for forming tetradentate titanium are required, and deep dealumination of the mordenite molecular sieve is required.

In general, acidic substances such as hydrochloric acid and nitric acid are used for removing aluminum element in a molecular sieve, and the mechanism is that aluminum element is dissolved through the acidity of strong acid. However, strong acid has high requirements on equipment materials and high investment cost. The common method for supplementing titanium to mordenite is a gas phase method, in which a titanium-containing compound is gasified and then passes through a bed layer containing zeolite at a high temperature, so that titanium is deposited in a zeolite framework at a certain temperature. The method has complex process and difficult amplification, and is not suitable for industrial production.

Disclosure of Invention

In view of the above, the invention aims to provide a method for preparing mordenite with titanium-containing high silica-alumina ratio, so as to solve the problems of difficult dealumination, high cost, complex process, unsuitability for industrial production and the like of the existing mordenite, and simultaneously improve the titanium utilization rate and the titanium content of the product in the mordenite titanium modification process.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

a method for preparing mordenite with titanium and high silicon-aluminum ratio comprises the following steps:

s1: dissolving a titanium source and oxalic acid in a solvent to prepare a modified solution;

s2: adding hydrogen mordenite into the modified liquid, and stirring to be uniform to obtain a modified liquid cement;

s3: placing the glue solution obtained in the step S2 into a reaction kettle, stirring and heating, slowly adding water into the reaction kettle while stirring, and continuing the reaction after the water is added until the modified mordenite glue solution is obtained;

s4: and (4) cleaning the modified mordenite glue solution obtained in the step (S3) to be neutral, drying by hot air, and then calcining to obtain the titanium modified mordenite with the high silica-alumina ratio.

The preparation method of the mordenite containing titanium and having high silica-alumina ratio uses a liquid phase deposition method to prepare a modified solution by placing a molecular sieve in a solution of oxalic acid and a titanium source, and the solvent of the modified solution selects an anhydrous organic solvent to ensure that the titanium source is not decomposed into titanium oxide in advance. Heating the modifying liquid to a certain temperature, adding water at a certain speed, slowly hydrolyzing the titanium-containing compound with the addition of the water to generate acidic substances such as hydrogen chloride and the like and titanium oxide, and under the hydrothermal condition, jointly acting the hydrogen chloride and oxalic acid on the aluminum in the mordenite molecular sieve to remove the aluminum from the molecular sieve framework. Meanwhile, titanium oxide generated by hydrolysis is deposited in the molecular sieve framework and gradually crystallized into titanium with a four-coordination framework. Through the treatments, the titanium-containing mordenite molecular sieve with high silica-alumina ratio is obtained. By adopting the preparation method, dealumination and titanium supplement are simultaneously carried out by a one-step method, not only can the mordenite be deeply dealuminated, but also the titanium utilization rate and the titanium content of the product can be obviously improved.

The invention adopts oxalic acid to dealuminate the mordenite, and the dealumination of the oxalic acid realizes the dissolution of aluminum through the combined action of the acidity and the complexing capacity of the oxalic acid.

Further, in the step S1, the titanium source is one of titanium fluorotitanate, titanium tetrachloride, isopropyl titanate, and titanium isooctanolate, and the titanium content in the titanium source is 0.1 to 1kg, preferably 0.2 to 0.5kg, in terms of equivalent of TiO 2.

Further, in the step S1, the amount of oxalic acid is 10 to 50 kg.

Further, in the step S1, the solvent is one or more of methanol, ethanol, tert-butyl alcohol, ethylene glycol, acetonitrile, toluene, and ethyl acetate, the total amount of the solvent is 20-80kg, and the amount of the hydrogen-type mordenite added is 5-15 kg.

Further, in step S1, the total amount of solvent is 50kg, and the amount of hydrogen-form mordenite added is 10 kg.

Further, in step S2, the particle size of the hydrogen-type mordenite is 50 to 1000nm, and the silica-alumina ratio is 5 to 10.

Further, in the step S3, the heating temperature is 100-.

Further, in the step S3, the reaction time is 24 hours, and the water adding rate is 0.05 kg/h.

Further, in the step S4, the calcination temperature is 550 ℃, and the calcination time is 4 h.

The preparation method of the mordenite containing titanium and having high silicon-aluminum ratio has the following advantages:

(1) the dealuminization titanium supplement modification method provided by the invention is simple and easy to realize large-scale industrial production;

(2) the dealuminization titanium supplementing modification method provided by the invention has the advantages of good titanium supplementing effect, high titanium content and no free titanium oxide;

(3) the dealuminizing titanium supplementing modification method provided by the invention has high titanium supplementing efficiency and high titanium utilization rate.

Detailed Description

The invention will be described in detail with reference to specific embodiments. The examples are intended to illustrate the invention, but are not intended to limit the scope of applicability of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.