The method of synthesizing zeolite on cordierite carrier
Technical field
The present invention relates to the method for load synthetic zeolite, be specifically related to the method for synthetic MCM-22 zeolite on the cordierite ceramic carrier.
Background technology
Support type zeolite (zeolite membrane on the carrier) has very on catalytic science and separation science, and important use is worth.As the membrane reactor that is used for the petrochemical industry separation process has all utilized the zeolite that loads on the different carriers with the monoblock type catalytic converter that is used for purifying automobile tail gas.General load zeolite has two kinds of methods: the one, and carrier immersed contain in the slurries of zeolite, make carrier surface load one deck zeolite, be called the load method, this method is simple to operate but can cause zeolite overlay and carrier surface in conjunction with not firm, and zeolite layer is peeled off easily.Another kind method is called original position load synthetic technology, is about to porous carrier and is immersed in the solution of synthetic zeolite, makes carrier surface one deck zeolite of firmly growing under the synthesis condition of zeolite.
Cordierite ceramic belongs to the category of high-performance ceramics, and its outstanding characteristics are that thermal coefficient of expansion is low, good adsorption performance, and specific area is big, fire-resistant degree height.Cordierite ceramic is widely used in vehicle exhaust to be handled, and ozone suppresses catalysis, and fields such as toxic gas purification are a kind of ecological environment material nds of function admirable.Patent US4800187 uses the original position synthetic technology to synthesize multiple zeolite on the ceramic honey comb surface, patent US4904518 has synthesized ZSM-5 in the silicon chip surface hydro-thermal, multiple zeolite such as ZSM-11, but what the shortcoming of above-mentioned patented technology was a zeolite in the carrier surface growth is very inhomogeneous, so patent CN99112822 has proposed elder generation's dip-coating one deck on cordierite ceramic and contains Al
2O
3, SiO
2And Na
2The coagulant liquid of O and then carrying out the synthetic method of load utilizes the series of chemical that takes place in the dip-coating process, can make very firm that carrier surface combines with zeolite layer.Its series of patents 99120818 adopts identical method to synthesize ferrierite on cordierite; The problem that the method is brought is that the dip-coating layer is introduced new material as the synthetic part material of zeolite, participates in building-up process, causes synthesis condition requirement harshness, is unfavorable for the synthetic of zeolite.
Summary of the invention
The invention provides the method for original position synthetic zeolite on a kind of cordierite carrier, by cordierite carrier is handled, effectively increase the outer specific surface that helps zeolite-loaded growth, and the original position that does not influence the MCM-22 zeolite is synthetic, make the load zeolite evenly firm, method is simple, and synthesis condition is easy to control.
Method provided by the invention is: cordierite is adopted the Combined Treatment of acid back alkali earlier, cordierite is immersed in the acid solution that mass concentration is 30-80%, handled 3-15 hour down at temperature 60-80 ℃, spend ion-cleaning after the taking-up, be in the sodium hydroxide solution of 4-20% in mass concentration again, handled 4-12 hour deionized water washing then, drying for temperature 60-80 ℃ down; With the cordierite carrier handled well in the synthetic liquid of 140-180 ℃ MCM-22 crystallization 3-10 days, make the load of MCM-22 zeolite original position grow in carrier surface.
In the method for the present invention, oxalic acid, citric acid, the more weak acid of acetic acid equal strength are preferably adopted in acid treatment.Processing procedure is gentle relatively, easily control.
In the method for the present invention, the synthetic liquid of described MCM-22 comprises common components such as silicon source, aluminium source, alkali, template agent and water, and wherein the silicon source is selected from silica gel, silicic acid or ethyl orthosilicate etc.; The aluminium source is selected from sodium metaaluminate or aluminum sulfate etc., and alkali is NaOH, and the template agent is hexamethylene imine (HMI), and the batching of the synthetic liquid of wherein said MCM-22 is calculated with oxide (mol ratio) and consisted of:
SiO
2∶Al
2O
3∶Na
2O∶HMI∶H
2O=1∶(0.2-0.33)∶(0.1-0.3)∶(0.35-0.7)∶20。The collocation method of synthetic liquid and crystallization process are method commonly used.
Effect of the present invention: the present invention is directed to cordierite itself and consist of 2MgO2Al
2O
35SiO
2Component and crystal structure characteristics adopt the Combined Treatment of acid back alkali earlier to cordierite, utilize the crystal structure of acid treatment partial destruction cordierite earlier, make wherein part MgO and Al
2O
3Dissolving, and SiO
2Exist in the pottery in unformed mode, utilize aqueous slkali then SiO
2Stripping so not only can effectively increase the outer specific surface of cordierite and the part Si O of stripping
2And Al
2O
3In the synthetic liquid of MCM-22, form a large amount of-OH group, help the load growth of zeolite.Thus the cordierite carrier upper surface synthesize growth evenly, in conjunction with firm MCM-22 zeolite.The inventive method is simple, and synthesis condition is easy to control, and processing cost is low, is easy to industrialization, is applicable to various cordierite carriers.
Description of drawings
Fig. 1 is the typical XRD characterization result of load MCM-22 zeolite of the present invention.
Fig. 2 is cordierite area load MCM-22 zeolite Electronic Speculum result of the present invention.
The specific embodiment
Open in detail below in conjunction with embodiment to the present invention, but the invention is not restricted to following examples.
Embodiment 1
The cordierite that with volume is 5ml is in mass concentration is 50% oxalic acid solution, handled 6 hours down for 80 ℃, the deionized water washing is to neutral, put into mass concentration then and be 10% sodium hydroxide solution, handled 5 hours down for 80 ℃, the washing back puts it in the synthetic liquid of MCM-22 then 120 ℃ of dryings, and the mol ratio of each component is SiO in the synthetic liquid of MCM-22
2: Al
2O
3: Na
2O: HMI: H
2O=1: 0.33: 0.1: 0.35: 20, the silicon source of employing is a silica gel, the aluminium source is a sodium metaaluminate.Crystallization is 72 hours under 140 ℃ of degree.Take out the cordierite after handling, at 120 ℃ of dry 12h, 540 ℃ of roastings 10 hours, ultrasonic cleaning 20min, the XRD characterization result is seen Fig. 1, illustrates that the MCM-22 zeolite has been synthesized in load on carrier, Electronic Speculum as a result (see figure 2) show the cordierite surface firmly load one deck MCM-22 zeolite, ultrasonic processing can not make it peel off, and the computational load amount is 50%.
Embodiment 2
Vehicle treated process and load building-up process are with embodiment 1, and employing concentration is 60% citric acid, and treatment temperature is 70 ℃, and the time is 10 hours.Used silicon source is an ethyl orthosilicate, and XRD result shows that the load zeolite is the MCM-22 zeolite, and load capacity is 40%.
Embodiment 3
Vehicle treated process and load building-up process are with embodiment 1, and the mol ratio of synthetic each component of liquid of MCM-22 is SiO
2: Al
2O
3: Na
2O: HMI: H2O=1: 0.25: 0.12: 0.35: 20, XRD result shows that the load zeolite is MCM-22 and part modenite impurity.
Embodiment 4
Vehicle treated process and load building-up process are with embodiment 1, and 5% sodium hydroxide solution is adopted in the alkali treatment after the acid treatment, handle 8 hours down at 70 ℃, and the solution composition of the synthetic MCM-22 of load is SiO
2: Al
2O
3: Na
2O: HMI: H
2O=1: 0.33: 0.1: 0.4: crystallization is 72 hours under 20,150 ℃ of degree.Take out drying and roasting, XRD figure shows that the load zeolite is the MCM-22 zeolite, and the load capacity before and after the ultrasonic processing is respectively 55% and 50%, illustrates that zeolite and carrier are in conjunction with firm.