FR2543530A1 - Process for the preparation of new alkali metal mixed silicates and of complex metal silicates for glassware and catalysts - Google Patents

Abstract

The aim of the new invention is the manufacture of new alkali metal mixed silicates for vitrifiable compositions with use of a part of the by-products in the vitrifiable composition to produce glass or foam glass. The invention also relates to the manufacture of complex metal silicates containing a plurality of metal elements grafted onto the same silica chain by reacting an alkali metal mixed metal silicate with another metal salt. This compound is useful in the field of catalysis. The application of the invention is the manufacture of new alkali metal mixed silicates for glass and foam glass, as well as the manufacture of complex metal silicates for catalysts and pigments.

Description

The object of the present invention is to synthesize new metal-alkali mixed silicate compounds in order to manufacture either new vitrifiable compositions for glassware or glass foam, or to manufacture new metal silicates by their more complex structure.

It is known in the previous French patent applications No. 8107189 or 81143 the preparation of metal silicates of Rm between 4 and 10 and the manufacture of metal-alkali mixed silicates of Rma also between 4 and 10 from alkaline silicates of Rma chooses between 2 and 5. It is also known mixtures of metal silicates and silica in the patent
FR 1 486327.

Rma is the ratio of the number of moles of silica to the number of moles of alkaline elements of the initial alkali silicate or contained in the mixed silicate formed.

Rma = mole SiO2 Rm = mole SiO2
mole Y2O mole MO
Y is an alkaline element, MO is a metal element oxide excluded alkali and counted in cations equivalent to M
Rm is the molecular ratio of the number of moles of silica to the number of moles of metal elements counted as the bivalent oxide NO of the metal silicate or mixed silicate formed excluding the alkali elements.

In the previous patent applications Nos. 8107189 and 8114316 and FR No. 82/00166, mixed silicates are mentioned which are prepared in two successive stages.

-1) Formation of metal silicate of -Rm between 4 and 10, from alkali silicate which will precipitate in a solution containing the. necessary amount of metal salts and complementary free acid so that said silicate is obtained.

-2) Then in a second step, this mixed silicate is attacked by a fairly strong base such as alkali metal hydroxides, aluminates or metaborates so that the amount of said alkaline bases does not exceed half the amount of alkaline bases present in the initial alkali silicate, on the other hand.

Apart from it has just been observed that the metal silicates prepared by the process previously described in said applications can react in step n 2 with alkaline silicates in the same
Proportions that strong bases such as alkali hydroxides aluminates and the like, or more precisely in the equivalent amount counted alkali hydroxide corresponding maximun to half of the alkaline elements counted alkali hydroxide initially present in the alkali silicate used in the preparation of the metal silicate. This is due to the essentially linear structure of the metal silicate. The attack of a metal silicate obtained in the process described in FR No. 2,485,77 by alkaline silicate does not give the same results, the reaction is not complete and the Filtration is more difficult because alkaline silicate remains in solution that has not reacted in large quantities. This is due to the structures of the metal silicates which are different. In the 1 case, linear chain metal silicates are formed while in the case cyclic chains are formed which do not have the same chemical properties in suspension in a solution.

On the other hand, it has been observed that it is possible to attack these latter cyclic lead silicates with a sufficiently strong base such as, for example, potassium hydroxide and the like, so as to form new mixed silicates having an between 1 and 4 and Rm less than 4. The amount of strong base is that corresponding to half that of the alkaline elements of alkali silicate initia counted alkali metal hydroxide.

These two new observations are very interesting economically and make it possible to manufacture new vitrifiable compositions from the mixed silicates thus prepared by melting them alone or in mixture to obtain glasses.

In order to further illustrate these two new products, here are two illustrative but non-limiting examples.

Example No. I
Mixed lead-potassium silicate of Rma between 0.2 and 4 from metal silicate of Rm between 2 and 5.

step n I
Mix 155 g potassium silicate with Rma = 3.7-21.2% SiO2 and 8.9% K2O at a time with 49 g lead nitrate.
Pb (NO3) 2 dissolved in 250 cm3 of water shake vigorously (mixer) until a suspension is obtained, then allow to stir for 30 minutes.

step n 2 add 8 g of potassium hydroxide dissolved in 30 cm3 of water in I5 min and allow to stir for 15 minutes. The filtration of the mixed product obtained is easy and provides a product having 65% moisture and weighing 84 g dry.

After drying in an oven between 100 and I40 C, a product having the following characteristics is obtained
SiO2 = 39.1% by mass
PbO = 39.3% by weight

- K2O = 4.3%
- KNO3 = 11.0%
- loss on ignition 13,5%
Characteristics of the waters are 0.03 molelim3 of free KOH, for 280 cm3 of marine waters.

Glass obtained
-SiO2 = = 44.5 ss
- PbO = 44.3%
K2O = 10.7% yields: SiO2 100%, Pb0 100%, K20 92%.

Here is the example n 2, presenting a new mixed silicate in that they have a Rm up to 14 maximun and they are prepared by attacking a metal silicate of Rm between 4 and 10 by An alkaline silicate in an amount previously stated This attack only gives good results in the case where the metal silicates are prepared according to the patent application number 8107189, or 8114316 and 82/00166
Example 2:
Silicate mixed lead potassium step n I /
Introduce 45 g of Pb (NO3) 2 lead nitrate into a beaker with 135 g of water. Dissolve. Add 52.2 cc of nitric acid at 4.76 mole / dm3.

Add 100 g of water. Introduce at once 260 g potassium silicate at 19.4% SiO2 and 9.4% IC20. Mix vigorously manually (or mixer-mixer) then mechanically until a suspension, stir 35 minutes.

step 2 Put 125 g of potassium silicate in a dropping funnel, add it very slowly at the beginning, taking care not to let the viscosity of the suspension increase too much. Stop the addition of if necessary if necessary several times, then when the ph suf fi ciently increased, add the remaining alkali silicate faster about 45 minutes of introduction. Leave to stir for 20 minutes and then filter the mixed silicate obtained. The reaction was made at 0 ° C, but other temperatures would be fine.

Characteristic of the unwashed powder after oven drying IIO C
SiO2 = 55.4% by mass
- PbO = -22.2
- K2O = 8.1%
- KNO3 = 8.8%
- loss on ignition from 25 to 950 C = I0.3%
The product having 59% moisture clears drying 136 g of dry product.

Characteristics of mature waters about 0.43 kg of mother water having an alkalinity of 0.034 mole / dm3 in free potash.

Reaction yields
SiO2 = 99.5%, PbO = 100%, K2O = 95%.

Glass obtained after fusion
-SiO2 61.7%
-PbO 24.7%
-K2O 13.6%
It should be noted that it is possible to mix the two products of example n I and n 2 in equal proportion to obtain a new glass. 50 g of the product of Example 1 are mixed with 50 g of Example 2 to give a glass. of composition SiO2 = 53.2%, PbO = 34.6%, and K20 = 12, I%. Note that. the metal salts may be in a mixture.

 Alas, it is known that the decomposing alkaline nitrates emit toxic gases such as nitrogen oxides, that is why it is necessary to reduce their concentration in mixed silicates by, wash, off it is interesting when lion It is of interest to know also that alkali acetates can be used as a reducing agent in vitrifiable compositions, this becomes particularly interesting when making a silicate of lead. It suffices that there is alkali acetate in the vitrifiable composition in a quantity lower than that of the alkaline nitrate to obtain a reduction of the nitrogen oxides by the decomposition gases of the alkali metal nitrate. alkaline acetate Essentially formed gases are then dioxide d! carbon, water and nitrogen which refine much more quickly vitrifiable compositions of this type. It is useless to put then classic refining such as Sb2O3 or As203.

Here are two interesting examples describing the uses of the two alkaline salts.

Example # 3 Step na I /
Introduce 180 g of 25% lead nitrate in a beaker with 50 cm3 to 4.85 mole dm3. Add 260 g of potassium silicate at once> 4% in SiO 2 and 9.4% in K 2 O. Stir vigorously when the suspension is obtained, then stir for 40 min and then proceed to stage n 2.

step 2
Introduce in 10 minutes 4 g of potassium hydroxide dissolved in 20 cm3 of water, let stir 20 minutes and then filter without voluntarily washing the precipitate, the humidity is 60%.

Product Features A
- SiO2 = 46.4%
- PbO = 27.9%
- K2O = 3.2%
- KNO3 = 16.5%
- loss on fire = 14%
Make the same product with 44.3 g of lead acetate dissolved in I50 g of water with I4.5 g of free acetic acid free, it is obtained under the same conditions the product B of the following characteristics.

SiO2 = 43s6 ss
- PbO = 26.0%
- K2O = 3.0%
- CH3CO2K = 14.3%
- loss on fire 13%
If this composition were melted alone the lead silicate would be reduced to lead.

It suffices to mix, for example, 100 g of A and 100 g of B to obtain the following composition glass
- SiO2 = 54.7%
- Pb0 = 32.7%
- K2O = 12.5% These are only illustrative and non-limiting examples giving free rein to the imagination when possible combinations provided that the amount of molar alkali acetate is less than that in nitrate. Acetate lead can be prepared by attacking lead with acetic acid in the presence of oxidant (krN03;
It has appeared as interesting also the manufacture of glass foams from calcium-sodium mixed silicate prepared directly and disintegrate in the presence of a previous vat. the fact that it is possible to recycle the nitrate-treated water produced by attacking limestones by supplementing with concentrated nitric acid is very advantageous, in fact, when the old waters are saturated with nitrate of soda, it is possible to use in parallel the same manufacture of calcium-sodium mixed silicate using a chloride as anion and the precipitate is weakly washed with water. It is then sufficient to mix the two compounds in the appropriate amounts and to add charcoal powder to the vitrifiable composition for glass foam. Said composition being heated to 800-I000 C and output of the furnaces as soon as it has swelled. This gives rise to good thermal and sound insulation materials.

EXAMPLE 4 Dissolve 41.4 g of calcium nitrate in 150 cm 3 of water, then 245 g of sodium silicate of 29.2% SiO 2 and 9.2% of K 2 O are added all at once. It is obtained a paste which was désaipaisit to give a sort of infiltrable oreme.Elle is poured, disintegrated in 150 cm3 of solution containing for example 43 g of preceding sodium nitrate, it is obtained directly a mixed filterable silicate of humidity 60% and composition when dry
- SiO2 = 60.4%
- CaO = 12.0%
Na2O = 6% compound C
- NaNO3 = 21.7%
- loss on ignition = 19.4%
It is possible starting from 28 g of calcium chloride in the same conditions without washing and without nitrates to obtain the following compound D:
- SiO = 67.6%
- CaO = I3.5%
- Na2O = 6.6 g
NaCl = 7.6 g
- Loss in the fire = Mix 100 g of D with 100g of C by intimately mixing 2t8 g of charcoal, so as to improve the foaming qualities of the batch composition. It is obtained in the muffle furnace at around 900 C of the glass foam that it is possible to mold
Whether suitable for thermal insulation or ceiling decoration, the dyes for glass foam panels can be obtained by the introduction of soluble soluble salts initially.

 In addition to applications in glassware and glass foam the si.

mixed silicates have a very interesting application in synthesis especially in the manufacture of complex metal silicates containing in the anemo molecule, metallic elements and possibly alkaline elements These complex silicates have a certain interest in the field of catalysis, especially that in fluidized bed . Indeed, it is known mixtures of silicas dtalumine and oxides of transition metals of the periodic table.

 But if one wants to use a catalytic mixture of different oxide it is created inside the support of the displacements of the oxides disputes and a sort of classification and segregation of these disputes oxides tending to reduce the catalytic activity.

The solution which will be proposed below is a new method of synthesis and the manufacture of a new compound having the wash of a chemical combination on which all the metallic elements will be grafted on the same siliceous chain. This will develop fluidized bed catalysis in the case where a mixture of metal oxides is needed as catalysts. This. compound is not: a mixture of metal silicates but a compound containing several metallic elements grafted on the same malecule ..

The method of manufacture forces the metal elements to be fixed as the manipulator desires.

This method consists in first making a metal silicate such as those indicated in patent applications Nos. 8107189, 8114316 and 82/00166. Then, in a second step, a sufficiently strong base is formed within the limit of half the quantity of alkaline elements counted as alkaline hydroxide present in the alkali silicate at the beginning. This suspension containing the mixed silicate is then reacted in a solution of another metal salt different from that of the starting material. Then, repeat a feed with a strong base and again pour the suspension into another metal salt. different from the other two and so on so get all the metal elements rigged on the same
ohaine of silica this to the. place and in the order in which it is desired.

 It has not been heretofore reported of a method which makes it possible to produce mixtures of silicas and of mixed metal silicates in French Patent No. I 486 327. The manufacture of metal silicates alone or in mixtures by simple substitution is also known. .

As an illustration, here is an example of manufacture of a metallic silicate of copper, cobalt, nickel. before developing this example, it is useful to note that amounts of free acids can partly replace a cation.

Example 5:
Silicate copper and copper potassium step n I:
Put 33 g of copper nitrate Cu (NO3) 2.3 H2O in solution in 150 cm3 of water, stir and add 33 cm of nitric acid to 7.35 mole / dm3. Then introduce 260 g of potassium silicate, 19.4% SiO 2 and 9.4% K 2 O, two times, mix well and continue stirring until the suspension is 25 minutes. The precipitate is blue colorless solution.

step 2 Dissolve 7 g of potassium hydroxide in 50 cm3 of water and then add it in stirring for 15 minutes in the solution of stage I, stirring for 25 minutes, the pH being around 10 on the Ph paper. The mixed silicate so manufactured can be filtered and dried, the humidity is 65% the color is blue.

Silicate of copper and cobalt then Be euavre cobalt potassium step n 1
Introduce the preceding suspension of mixed potassium potassium silicate in a solution of cobalt nitrate containing 18.2 g of cobalt nitrate Co (HO 3) 2, 6H 2 O dissolved in 80 cm 3 of water. The cobalt binds itself necessarily to the siliceous chain which was already grafted on the copper. Which is all the interest.

step 2
Before continuing decant and separate 80 cm3 of water. Then add again 7 g of potash dissolved in 30 cm3 of water in 10 minutes. The mixed cobalt potassium cobalt silicate can be filtered and then dried at 11 ° C oven with the following composition:
- SiO2 = 63.1? mass
CuO = 13.6
- CoO = 5.9%
- K2O = 7.2%
- KNO3 = 1.2 ss
The loss on ignition at 900 C is 9.3%. It is possible to continue the grafting of other metal cations on this silicate remained in suspension.

Copper silicate, cobalt, nickel.

Take the previous suspension, add it in 15 minutes in a nickel solution containing 18.2 g of Ni (NO 3) 2, 6 H 2 O per 50 cm 3 of water. Leave to shake for 20 minutes, then filter thoroughly, dry in an oven at 120 ° C. A nickel cobalt copper metal silicate having a moisture content of 64% is obtained and the following mass composition:
- SiO2 = 63.9%
- CuO = 13.8%
- CoO = 6.0%
- NiO = 5.9%
- KNO3 = 1.0%
- Loss on fire = 10.5%
It is possible to continue to add alkaline and other metallic elements so as to make the catalyst that will contain all the metal elements that are desired supported by the same chain of silica. It should be noted that all the soluble salts are usable provided that there are no incompatibilities between the anions and the cations of the various salts.

All nitrates are soluble. These metal silicates are of great interest because of their structures which ensure a perfectly homogeneous composition of interest for fluidized bed catalysis and the like. Only transition elements of the periodic table have been used in Example 5, but other elements can be introduced, for example calcium, magnesium, aluminum which, depending on the properties, may be add as the soluble aluminum salt in step n I or as aluminate in step n 2.

The structures are difficult to verify, the two methods of their identification remaining the differential thermal analysis at high temperature and the nuclear magnetic resonance on the silillation products of the metal silicates thus obtained.

All examples are illustrative but not limiting. It is easy to understand that these new vitrifiable compositions have a certain advantage over traditional compositions.

The new or mixed metal silicates containing at least one transition element have a great interest in catalysis and for the pigments.

 The application of the invention is the production of vitrifiable compositions for glassware and glass foam. The application is also the manufacture of complex metal silicate for catalysis or certain pigments.

Claims (5)

CLOSES Rm silica on metal oside counted at 110 is obtained from Rm equal to IO then attacked by a fairly strong base contained at most 0.55 times the amount of basic alkaline elements contained in the initial silica and alkaline so as to obtain a silicate alkali of Rma between 0.2 and 14. -1) Process for obtaining mixed metal silicates alkali metal characterized not that a metal silicate of molecular ratio -2) A method according to claim I in the case where the metal silicate is prepared by substitution of metal salts and free acid in an amount complementary to the total substitution of the alkali silicate, characterized in that the strong base can then be a soluble alkali silicate. -3) Process according to claim 1 and 2 characterized in that in the case of soluble lead salts such as advantageously acetate and lead nitrate it is possible advantageously to leave a portion of the nitrates and acetates alkali in the mixed silicate mixed so that the amount of acetate is less than that of nitrates. -4) A method according to claims I and 2 characterized in that obtaining 1 glass foam is obtained by leaving alkaline nitrates in the precipitate in sufficient quantity mixed with good char. 5) Novel products obtained by the process according to one of claims 1, 2, 3 and 4 in order to obtain vitrifiable compositions for the manufacture of glass or glass foam -6) Process for obtaining novel metal silicate compounds according to claim 1, characterized in that the mixed alkali metal silicate is reacted with a metal salt solution. -7) new metal silicate obtained by the process according to I, 6, characterized in that it contains at least two different metal elements chemically bonded to the same silica chain, at least one of the metals is a transition element of the classification periodic.  -8t) new metal silicate according to 7 characterized in that this complex silicate contains voluntarily and optionally alkaline elements.