Catalyst – solid sorbent – or support therefor: product or process – Solid sorbent – Silicon containing
Reexamination Certificate
2000-09-18
2002-01-15
Bell, Mark L. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Solid sorbent
Silicon containing
C502S080000, C502S084000, C502S414000, C502S527120, C502S527130, C502S527140, C502S527240, C502S410000, C501S141000, C106S415000, C106S416000
Reexamination Certificate
active
06339040
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention concerns a composition of adsorbent containing phyllo-alumino silicate containing schistose particles having at least partially a layered structure with substantially parallel layers, whereby they at least for 30 percent by weight consist of 14 Å phyllo-alumino silicate. The distance between two adjacent structural layers is greater than 5 &mgr;m, but less than 100 &mgr;m.
SUMMARY OF THE INVENTION
The use of berngite as an absorbing alumino sicilate containing schistose material is known. The preparation of this material requires heating at high temperature (600° C. and more) in a furnace. Such heating requires not only large expenditures, but is also ecologically harmful, because harmful substances and gases are released during heating. Moreover, such heating is very expensive as regards investments (furnace) and as regards the use of fuels. Beringite has an absorption power which is limited.
In the state of the art, there is no mention of the particular effect of the application of specific aluminum particles with a minimum specific surface area of 100 m
2
/g which are attached onto specific 14 Å phyllo-alumino silicate, neither of a maximum length or diameter of the aluminum particles, nor of a minimum percentage by weight of aluminum containing di-octahedric layers in the 14 Å phyllo-alumino silicate, nor of the distance between two adjacent di-octahedric layers. In the state of the art, there is neither mention of a synergy at relatively low pH (6.5-8.5) between OH groups on the micronised and also etched aluminum plates or particles and the absorption thereof on the heavy metals, which in this way causes a flocculation.
This use of micronised and etched metallic plates or flakes is not limited to aluminum, but is also valid for all other tri- and bivalent metal particles and their alloys, as well as their mixtures (Al—Cu, Al—Cr, Cr, Cu, Cr—Cu, Ni, Ni—Fe, Fe—Cr, etc.).
It has now been found that specific alumino silicate containing schistose particles, which are provided with specific impurities (such as Me, Cu, Zn, Pb, Ni, Cd, Cr) in the crystal lattice, possess excellent sorption efficiency. The invention thus concerns a composition of adsorbent containing alumino silicate containing schistose particles which at least partially have a layered structure, whereby, at least for 30 percent by weight of the alumino silicate containing schistose particles, the distance between two structurally adjacent layers is greater than 5 &mgr;m, but less than 100 &mgr;m.
The particles consist at least partially of aluminum containing di-octahedric layers. Preferably, at least 25 percent by weight of the particles consist of aluminum containing di-octahedric layers. The particles are provided on their inner and outer layers of metallic particles or flakes or spangles (aluminum, iron, chromium, iron-chromium, Ni, Cr—Ni, Al—Ni, Al—Cu, Al—Cr) with metallic hydroxide ions (hydroxylation), whereby these metallic particles are at least partially bound onto and between two structurally adjacent layers by adhesion or other physicochemical forces. These flakes preferably form a substantially complete metallic layer onto the phyllo-alumino silicate particles. At least 50 percent by weight of the metallic flat particles or flakes have a maximum length or diameter between 6 and 60 &mgr;m, a thickness of a few &mgr;m (2 to 5), and a specific surface area greater than 100 m
2
/g, due to the size and the etching.
In the present context, the specific surface area of particles is determined by nitrogen adsorption using the B.E.T. (Brunauer, Emmet, Teller) method, as simplified by Haub and Dümbgen. The apparatus used is the Ströhlein Area-Meter II, available from Ströhlein A. G. in Germany, the manual of which refers to the simplified B.E.T. method.
Alumino silicate containing schistose particles of the sorbent according to the invention are mainly 14 Å di-octahedric alumino silicate with an adequate microporosity and capillarity, onto which and within which hydrolysed metallic particles with OH
−
ions (aluminum hydroxide) are physically and chemically adsorbed or bound. The alumino silicate containing schistose particles can contain up to 40,000 ppm of metallic particles. The sorbent contains for example 5,000 to 20,000 ppm of metallic particles or flakes.
The metallic particles or flakes are preferably aluminum or aluminum oxide particles, which after hydroxylation are provided with aluminum hydroxide.
Preferably, at least for 30 percent by weight of the alumino silicate containing schistose particles, the distance between two structurally adjacent layers is greater than 10 &mgr;m, but less than 100 &mgr;m, for example greater than 5 &mgr;m but less than 10 &mgr;m. Still better is an average distance between two structurally adjacent layers of the alumino silicate containing schistose particles of about 10-20 &mgr;m, while the maximum average length of the metallic (preferably aluminum or aluminum oxide) flakes is between 10 and 60 &mgr;m. The metallic flakes are preferably etched particles with a specific surface area greater than 100 m
2
/g. This specific surface area is preferably greater than 150 m
2
/g, for example 200 to 500 m
2
/g. These metallic flakes preferably contain one or several open cavities with an irregular circumference. The diameter of a cavity ( [surface of the cavity/&pgr;]
1/2
) is preferably at least two times larger than the diameter of the flakes. The thickness of the walls of the particles around the cavity is for example less than 3 &mgr;m.
According to an embodiment, at least 50 percent by weight of the structure of weathered alumino silicate containing schistose particles consist of a 14 Å aluminum containing di-octahedric structure. The degree of weathering is indicated by the substitution of magnesium by aluminum which should at least amount to more than 50%.
Compositions of the adsorbent according to the invention, which are very suitable for the sorption and the fixation of heavy metals, carry aluminum hydroxide ions which are bound to one or several of the following elements: Fe, Cr, Cu, Ni, Co, Sr, Cd, Pb, Zn or Mn. It has been found that the epitaxy or in situ growth of the precipitated heavy metals preferably occurs on the di-octahedric alumino silicate crystal surfaces, on the sites where in the crystal lattice analogous or the same heavy metals occur as natural or artificial impurities, such as Cr, Cu, Ni, Co, Sr, Cd, Pb, Zn or Mn.
At least 50 percent by weight of the aluminum or aluminium oxide particles with hydroxyl ions preferably possess a specific surface area greater than 150 m
2
/g.
Preferably, in the alumino silicate containing schistose particles, 20 percent by weight of aluminum chlorite is present. For example, in the absorbing composition, at least 50 percent by weight of the alumino silicate containing particles may be aluminum chlorite.
According to an advantageous embodiment, at least 50 percent by weight of the alumino silicate containing schistose particles have a diameter greater than 500 &mgr;m. Preferably, the diameter of the particles is less than 2,000 &mgr;m.
According to an embodiment, the sorbent comprises porous particles, which show a weak acid reaction (with a pK
a
between 4 and 7).
According to another embodiment, the sorbent does or does not comprise adsorbed calcium and/or magnesium containing fertiliser, nitrate fertiliser, phosphate fertiliser, or a mixture thereof.
A composition according to the invention, which is suitable for the fixation of one or several heavy metals, contains di-octahedric phyllo-alumino silicate with as natural impurities in the crystal lattice a total of at least 500 ppm of one or several elements of the following series: Fe, Cr, Cu, Ni, Co, Sr, Cd, Pb, Zn or Mn.
The sorbent may also be mixed with active carbon for specific applications (removal of Hg, etc.).
Preferably, the alumino silicate containing schistose particles for at least 20 percent by weight consist of weathered or not weathered mica or for at l
Bell Mark L.
Hailey Patricia L.
Metal Adsorbens Promotion Company N.V.
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