GB2030974A - Mordenite Synthesis - Google Patents

Mordenite Synthesis Download PDF

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Publication number
GB2030974A
GB2030974A GB7930181A GB7930181A GB2030974A GB 2030974 A GB2030974 A GB 2030974A GB 7930181 A GB7930181 A GB 7930181A GB 7930181 A GB7930181 A GB 7930181A GB 2030974 A GB2030974 A GB 2030974A
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Prior art keywords
mordenite
kaolin
heating
hours
silica
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GB7930181A
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GB2030974B (en
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Saint Gobain Abrasives Inc
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Norton Co
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    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00Silicon; Compounds thereof
    • C01B33/20Silicates
    • C01B33/26Aluminium-containing silicates, i.e. silico-aluminates
    • C01B33/28Base exchange silicates, e.g. zeolites
    • C01B33/2807Zeolitic silicoaluminates with a tridimensional crystalline structure possessing molecular sieve properties; Isomorphous compounds wherein a part of the aluminium ore of the silicon present may be replaced by other elements such as gallium, germanium, phosphorus; Preparation of zeolitic molecular sieves from molecular sieves of another type or from preformed reacting mixtures
    • C01B33/2861Zeolitic silicoaluminates with a tridimensional crystalline structure possessing molecular sieve properties; Isomorphous compounds wherein a part of the aluminium ore of the silicon present may be replaced by other elements such as gallium, germanium, phosphorus; Preparation of zeolitic molecular sieves from molecular sieves of another type or from preformed reacting mixtures of mordenite type, e.g. ptilolite or dachiardite

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Silicates, Zeolites, And Molecular Sieves (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Abstract

A method of making mordenite comprises: (a) heating a reaction mixture at any first temperature in the range 25 to 100 DEG C for a time at least substantially 2 hours, said reaction mixture comprising water, free silica, sodium silicate, and meta kaolin; and (b) after (a), heating said reaction mixture for sufficient temperature and time to enable that mixture to give mordenite having a weight median particle size of at least substantially 6 microns. o

Description

SPECIFICATION Mordenite Synthesis This invention relates to the manufacture of synthetic large port mordenite.
The basic patent covering the synthesis of large port mordenite, i.e. mordenite capable of absorbing molecules larger than 5 Angstroms effective diameter -- or more simply, as distinguished from natural mordenite, mordenite capable of absorbing benzene, is United States Patent No.
3,436,174 issued April 1,1969.
A variety of raw materials, synthetic and natural, has been employed in the synthesis of large port sodium mordenite (U.K. Patent No. 298,606; United States Patent No. 3,436,174; United States Patent No. 3,445,184). The synthesis is usually carried out in one step at relatively low temperatures (75-2600C) under autogenous pressure. Normally the process comprises mixing the reactants, autoclaving of the mixture for a given length of time during which raw material is converted to zeolite, followed by filtration of the mixture to separate zeolite from mother liquor, and drying of the zeolite to remove excess water.
Kaolin is a particularly desirable raw material because of its availability and relatively low cost.
However, when synthesis of mordenite is carried out using kaolin as the primary source of alumina, the weight median particle size of the mordenite is low and very poor filtration rates are obtained. The present invention relates to a process of producing synthetic large port mordenite using kaolin such that increases are obtained in the weight median particle size and filtration rates of the mordenite.
The process, according to the invention can comprise conversion of kaolin to meta kaolin by calcination, followed by aging of the reaction mixture which contains the metakaolin and other ingredients in the temperature range of 25-1000C for two hours or more followed by the autoclaving of 1 50-2600C. The resultant mixture (a slurry) contains mordenite of large particle size (i.e. weight median particle size 26.0 y) and gives fast filtration.
Example 1 (Comparative) A sample of raw kaolin particles weighing 790 grams was dispersed in a solution containing 6734 grams sodium silicate (0.3 Na2O, 1.0 Si2, 7.5 H2O) and 11186 grams water. To the resulting mixture 794 grams of diatomaceous silica were added with continuous stirring. These quantities have a molar formulation of 0.91 kaolin, 10.90 sodium silicate, 210.22 water, 3.98 diatomaceous silica.The overall composition of the resultant reaction mixture, in terms of oxidemole rations, then corresponds to Na2O/SiO2=0.20 SiO2/AI203=16.70 H20/Na20=89.9 1 The reaction mixture was placed in a 18.93 litres (5 U.S. gallons) jacketed autoclave, provided with a mechanical stirrer and an oil heating unit, and allowed to crystallize at 1 740C for five hours. At the end of the crystallization period the mixture was quenched into an equal amount of water to give a slurry.A portion of the slurry was filtered and the resulting solid was washed with water to a neutral pH, then dried overnight at 1000C. This solid showed an x-ray crystallinity of 92% compared to a commercial mordenite sample obtained from Norton Company, and a weight median particle size of 5.4 microns. 200 ml of the slurry were filtered using a Buchner funnel of 7.11 cm in diameter, a Dacron filter cloth (Dacron is a Registered Trade Mark) of air porosity of 30 to 300 litres per min/m2 (0.1 to 1 cfmXft2) and pressure of 202 mmHg. It took 14 minutes for the filtration of this slurry.
Example 2 (Comparative) This example was carried out under identical conditions to those described in Example 1; except that the reaction mixture was digested at room temperature for 24 hours prior to autoclaving. The weight median particle size mordenite and cake formation time were 7.5 microns and 2 minutes, respectively. The mordenite content, however, was 32% by weight.
Example 3 (Comparative) A mixture consisting of 6734 grams sodium silicate, 794 grams diatomaceous silica, 598 grams kaolin that have been calcined at 61 00C for four hours, and 11379 grams water was prepared. These quantities correspond to Example 1 's molar formulation with the exception of water (213.86 moles) to account for that lost upon calcination of the kaolin. The oxide-mole ratios of the mixture were the same as listed in Example 1. The mixture was autoclaved at 1 740C for five hours. The mordenite weight median particle size, crystallinity and cake formation time were 6 microns, 89% and 6.5 minutes, respectively.
Examples 4 to 8 The following examples were carried out using the same formulation as in Example 3.
Each mixture was digested at 500C for 24 hours followed by autoclaving at 1 740C for a given period of time. Following this treatment the weight median particle size, filtration, and percent by weight mordenite were determined as described in Example 1. The results are summarized in the table below.
Example No. 4 5 6 7 8 Autoclave time, Hrs: 5 5.5 6 6.5 7 Percent by weight Mordenite 28 87 103 90 72 Weight median Particle Size, 40 7.5 6.6 8 6.9 Mordenite, microns Cake Formation Time, mins. 0.05 4.95 5.53 0.97 1.67 Example 9 (Comparative) Using the same oxide-mole ratios of Example 1, a mixture of 6734 grams sodium silicate, 794 grams diatomaceous silica, 790 grams raw kaolin and 111 86 grams water, was prepared. The mixture was digested at 500C for 24 hours followed by autoclaving at 1 740C for six hours. This gave mordenite having 77% crystallinity, 4.6 microns weight median particle size, and 1 5.3 minutes cake formation time.
Summary of Examples Example 1 This example shows the weight median particle size of mordenite, and cake formation time of a given formulation using raw kaolin without predigestion.
Example 2 Here we show that the room temperature digestion of a reaction mixture, utilizing the same molar formulation as in Example 1, leads to an increase in the weight median particle size of mordenite, and decrease in the cake formation time.
Example 3 This example shows that the utilization of calcined kaolin leads to some improvements in the weight median particle size of mordenite, filtration, and no impact on the mordenite quality.
Examples 4-8 These examples show that the utilization of calcined kaolin with digesting the reaction mixture, prior to crystallization, results in improving the weight median particle size and filtration of the mordenite. However, it is necessary to increase the crystallization time to achieve the highest quality mordenite as shown by Example 6. In all these examples the weight median particle size of mordenite and filtration are superior to those of Examples 1 and 2.
Example 9 This example demonstrates that the utilization of a predigested raw kaolin based formulation does not lead to any improvements in either weight median particle size or filtration of the mordenite.
Further tests have shown that preferably the diatomite (e.g. diatomaceous earth) should not be employed in excess of that amount required to provide 25% of the total weight of the silica and combined silica in the reaction mixture.
It will be appreciated from the above discussion that kaolin which has been converted to meta kaolin can be employed as the alumina source in the hydrothermal synthesis of mordenite; and that aging of the reactants prior to autoclaving improves the particle size and filtration characteristics of the mordenite.
In the above Examples 3-8, the kaolin provided by calcination comprises meta kaolin.

Claims (27)

Claims
1. A method of making mordenite, comprising: (a) heating a reaction mixture at any first temperature in the range 25 to 1000C for a time at least substantially 2 hours, said reaction mixture comprising water, free silica, sodium silicate, and meta kaolin: and (b) after (a), heating said reaction mixture for sufficient temperature and time to enable that mixture to give mordenite having a weight median particle size of at least substantialiy 6 microns
2. A method as claimed in claim 1, wherein in (a), said free silica is in an amount not more than 25% by weight of the total weight in (a) of free silica and combined silica.
3. A method as claimed in claim 1 or 2, wherein in (a), said free silica comprises diatomaceous earth.
4. A method as claimed in any one of claims 1 to 3, wherein in (a), said meta kaolin comprises meta kaolin obtained by calcination of a precursor thereof.
5. A method as claimed in any one of claims 1 to 3, wherein in (a), said meta kaolin comprises meta kaolin obtained by calcination of kaolin.
6. A method as claimed in Claim 5, wherein in (a), said meta kaolin comprises meta kaolin obtained by kaolin calcined at substantially 61 00C for substantially 4 hours.
7. A method as claimed in any one of claims 1 to 6, wherein in (a), said first temperature is substantially 50"C.
8. A method as claimed in any one of claims 1 to 7, wherein in (a), said time is at most substantially 24 hours.
9. A method as claimed in any one of claims 1 to 8, wherein in (b), said heating is at any sufficient temperature not above substantially 2600C.
10. A method as claimed in claim 9, wherein in (b), said heating is at any temperature in the range substantially 1 50 to substantially 2600C.
11. A method as claimed in claim 10, wherein in (b), said heating is at substantially 1 740C.
12. A method as claimed in any one of claims 1 to 11, wherein in (b), said heating is for at least substantially 2 hours.
1 3. A method as claimed in claim 12, wherein in (b), said heating is for at most substantially 7 hours.
14. A method as claimed in any one of claims 1 to 13, wherein in (b), said heating is in an autoclave.
1 5. A method as claimed in any one of claims 1 to 14, wherein said mordenite has a weight median particle size of at least substantially 6 microns and at most substantially 40 microns.
1 6. A method as claimed in claim 1, substantially as described in Example 4.
1 7. A method as claimed in claim 1 substantially as described in Example 5.
18. A method as claimed in claim 1, substantially as described in Example 6.
19. A method as claimed in claim 1, substantially as described in Example 7.
20. A method as claimed in. claim 1, substantially as described in Example 8.
21. Mordenite, made by a method as claimed in any one of claims 1 to 20.
22. A method comprising absorbing and/or adsorbing at least a portion of material by means of mordenite as claimed in claim 21.
23. A method as claimed in claim 22, wherein said material comprises molecules larger than 5 Angstroms.
24. A method as claimed in claim 22, wherein said material comprises benzene.
25. A method of making large port mordenite, capable of absorbing and/or adsorbing molecules larger than 5 Angstroms, by autoclaving below 2600C a mixture of water, silica, sodium silicate, and kaolin, characterized in that the kaolin is in the form of meta kaolin and the mixture is aged at 25 to 1000C for more than 2 hours prior to autoclaving, said autoclaving being carried out for a time sufficient to produce mordenite having a weight median particle size of at least 6 microns.
26. A method as in claim 25, in which the free silica is present in the mix in an amount not more than 25% of the total free and combined silica in the mix.
27. A method as in claim 26, in which the free silica is in the form of diatomaceous earth.
GB7930181A 1978-09-08 1979-08-31 Mordenite sythesis Expired GB2030974B (en)

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US94071178A 1978-09-08 1978-09-08

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GB2030974A true GB2030974A (en) 1980-04-16
GB2030974B GB2030974B (en) 1983-01-26

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JP (1) JPS5571620A (en)
CA (1) CA1139735A (en)
DE (1) DE2934382A1 (en)
FR (1) FR2435443A1 (en)
GB (1) GB2030974B (en)
IT (1) IT1119930B (en)
NL (1) NL7906638A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2125390A (en) * 1982-08-16 1984-03-07 Ici Plc Preparation of zeolites

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DD59075A (en) *
US3436174A (en) * 1967-10-18 1969-04-01 Norton Co Synthetic mordenite and preparation thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2125390A (en) * 1982-08-16 1984-03-07 Ici Plc Preparation of zeolites

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FR2435443A1 (en) 1980-04-04
CA1139735A (en) 1983-01-18
GB2030974B (en) 1983-01-26
DE2934382A1 (en) 1980-03-27
JPS5571620A (en) 1980-05-29
FR2435443B1 (en) 1982-11-26
NL7906638A (en) 1980-03-11
IT7968763A0 (en) 1979-09-04
IT1119930B (en) 1986-03-19

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 19970831