Silicates with high ion exchange capacity derived from sepiolite and processes for their production
AssigneeSynthesis Engineering Ltd.
InventorsAvelino C. Corma, Amparo C. Mifsud, Joaquin P. Perez
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Abstract
Silicate having high ion exchange capacity are obtained by reacting sepiolites with a base, preferably a strong base in the presence of a polar liquid at a temperature, preferably elevated, and for a period sufficient to increase the ion exchange capacity to at least 50 meq. per 100 g, more preferably at least 100 meq. per 100 g. In the preferred form, the reaction is carried out at above 100.degree. C. in an autoclave.
Claims20
A process for obtaining a silicate derived from a sepiolite comprising reacting said sepiolite with a base selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides and ammonium hydroxide, in the presence of a polar liquid selected from the group consisting of water, alcohols and mixtures thereof, at a temperature in the range from about 100.degree. C. to about 400.degree. C. and for a period sufficient to increase the ion exchange capacity of the sepiolite to at least 100 meq. per 100 g with respect to potassium or magnesium, and recovering a silicate with said ion exchange capacity.
A silicate having an ion exchange capacity with respect to magnesium of at least about 100 meq. per 100 g and conforming to the general formula
- Si.sub.y W.sub.w M.sub.x A.sub.z O.sub.30 (OH).sub.4
- wherein
- W is selected from the group consisting of aluminum, magnesium, iron, nickel, manganese and mixtures thereof;
- M is a divalent metal selected from the group consisting of the alkaline earth metals, and mixtures thereof;
- A is selected from the group consisting of alkali metals, ammonium ion and mixtures thereof;
- y is from about 10 to about 12;
- w is from about 3.5 to about 8;
- x is from about 0 to about 2;
- z is from greater than zero up to about 4;
- and
- the molar ratio w:y is from about 0.29:1 up to about 0.8:1.
A silicate in sodium form having been calcined at 250.degree. C. and having the formula Si.sub.y W.sub.x M.sub.x Na.sub.z O.sub.30 (OH).sub.4, wherein W is selected from the group consisting of aluminum, magnesium, iron, nickel, manganese and mixtures thereof;
- M is a divalent metal selected from the group consisting of alkaline earth metals, and mixtures thereof;
- y is from about 10 to about 12, w is from about 3.5 to about 8;
- x is from about 0 to about 2;
- and z is from greater than zero up to about 4;
- and having the following X-ray difractogram:
- ______________________________________ 20 d(A) I.sub.obs hkl ______________________________________ 6.9 12.80 s 110 19.7 4.50 w 060 20.4 4.34 i 131 26.5 3.35 i 080 34.4 2.60 w 441,281 35.2 2.54 w 371,191 36.5 2.45 w 202,042 ______________________________________
- wherein the relative intensities are ms=strongest, s=strong, i=intermediate and w=weak.
A silicate in nickel form having been calcined at 250.degree. C. and having the formula Si.sub.y Ni.sub.w M.sub.x A.sub.z O.sub.30 (OH).sub.4, wherein M is a divalent metal selected from the group consisting of alkaline earth metals, and mixtures thereof;
- A is selected from the group consisting of alkali metals, ammonium ion and mixtures thereof;
- y is from about 10 to about 12, w is from about 3.5 to about 8, x is from about 0 to about 2, and z is from greater than zero up to about 4, and having the following X-ray difractogram:
- ______________________________________ 20 d(A) I.sub.obs hkl ______________________________________ 7.10 12.44 s 110 17.54 5.05 w 150 19.64 4.51 i 060 20.50 4.32 i 131 23.60 3.76 w 260 26.46 3.36 i 080 27.70 3.21 w 331 34.60 2.59 i 371,191 36.50 2.45 w 202,042 ______________________________________
- wherein the relative intensities are ms=strongest, s=strong, i=intermediate and w=weak.
Dependencies are inferred from the claim text.