Carbon dioxide adsorbent and method for producing the adsorbent
First Claim
1. A method for producing a reversible adsorbent having between about 2.0 and 3.0 molecules of modifying agent per square nanometer and displaying near infrared bands at 7220, 6720, 6557, 5970-5480, 5270, 4945 and 4545 cm-1 for use in the removal of carbon dioxide comprising the steps of:
- providing a silica gel;
providing a clay material;
mixing said silica gel with said clay material to obtain a material containing between about 10 wt. % and about 30 wt. % of clay;
forming an extruded solid material from said silica gel-clay material; and
treating said extruded solid material in a solution containing a surface modifying agent so as to modify chemically the surface of said extruded solid material and thereby form said reversible adsorbent for removing carbon dioxide.
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Accused Products
Abstract
A reversible adsorbent for carbon dioxide, which can be used as a decontaminant of closed environments, has been devised. It consists of a novel material formed by a surface modified silica gel with active sites for the chemisorption of CO2 at room temperature combined with a clay which acts as an agglomerant in a preferred weight ratio of 80/20. The carbon dioxide is liberated under heating at 110° C. The surface area of the material ranges between about 120 and about 240 m2 /g with a total pore volume between about 0.4 and about 0.8 cc/g where about 80% of the total pore volume contains pores of a diameter between about 60 Å and about 180 Å. The material is capable of adsorbing between about 7.5 and 11.7 cc of dry CO2 per gram and can be regenerated between about 70° and about 150° C. without losing any adsorptive capacity. Dry carbon dioxide is chemisorbed as a surface ammonium carbamate which becomes a surface bicarbonate in the presence of water.
99 Citations
39 Claims
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1. A method for producing a reversible adsorbent having between about 2.0 and 3.0 molecules of modifying agent per square nanometer and displaying near infrared bands at 7220, 6720, 6557, 5970-5480, 5270, 4945 and 4545 cm-1 for use in the removal of carbon dioxide comprising the steps of:
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providing a silica gel; providing a clay material; mixing said silica gel with said clay material to obtain a material containing between about 10 wt. % and about 30 wt. % of clay; forming an extruded solid material from said silica gel-clay material; and treating said extruded solid material in a solution containing a surface modifying agent so as to modify chemically the surface of said extruded solid material and thereby form said reversible adsorbent for removing carbon dioxide. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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- 29. A reversible adsorbent for use in the removal of carbon dioxide from a gas, said adsorbent comprising a silica gel whose surface has been modified by an aminoalkoxysilane, said silica gel having a chemical composition consisting essentially of from about 70 to 80 wt. % SiO2, from about 10 to about 15 wt. % Al2 O3, from about 1.0 to 1.5 wt. % Fe2 O3 from about 8 to about 12 wt. % organic residue and from about 0.5 to about 0.9 wt. % trace impurities.
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39. A method for producing a reversible adsorbent for use in the removal of carbon dioxide comprising the steps of:
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mixing a material containing silica with a filler material so as to obtain a material containing between about 10 wt. % and about 30 wt. % of said filler material; adding water to said material in an amount sufficient to provide said material with a water content in the range of from about 35 wt. % to about 50 wt. %; extruding said material to form an extrudate; placing said extrudate in a reactor; adding a mixture of a silane surface modifying reagent in a concentration between about 5 vol. % and about 75 vol. % and a solvent in a concentration between about 25 vol. % and 95 vol. % to said reactor; agitating said extrudate and said mixture at a temperature between about 50°
C. to about 150°
C. for between about 4.5 hours to about 30 hours to form said reversible adsorbent for removing carbon dioxide;washing said adsorbent in a solvent; and drying said absorbent.
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Specification