Porous pellet adsorbents fabricated from nanocrystals

Abstract

Pelletized adsorbent compositions and methods of adsorbing toxic target compounds are provided for the destructive adsorption or chemisorption of toxic or undesired compounds. The pelletized adsorbents are formed by pressing together powder nanocrystalline particles comprising a metal hydroxide or a metal oxide at pressures of from about 50 psi to about 6000 psi to form discrete self-sustaining bodies. The pelletized bodies should retain at least about 25% of the surface area/unit mass and total pore volume of the starting metal particles.

1. A composite comprising a self-sustaining body formed of a plurality of agglomerated nanocrystalline particles having as avenge crystallite size of up to about 20 nm and selected from the group consisting of metal oxides and hydroxides and mixtures thereof, said body having a total pore volume which is at least about 90% of the total pore volume of said particles prior to said agglomeration thereof, said body having a density of from about 0.2 to about 2.0 g/cm 2 . 
     
     
       2. The composite of  claim 1 , said particles being selected from the group consisting of MgO, CaO, TiO 2 , ZrO 2 , FeO, V 2 O 3 , V 2 O 5 , Mn 2 O 3 , Fe 2 O 3 , NiO, CuO, Al 2 O 3 , ZnO, Mg(OH) 2 , Ca(OH) 2 , FeO(OH), Ni(OH) 2 , Cu(OH) 2 , Al(OH) 3 , Zn(OH) 2 , and mixtures thereof. 
     
     
       3. The composite of  claim 2 , said particles being MgO. 
     
     
       4. The composite of  claim 2 , said particles being CaO. 
     
     
       5. The composite of  claim 1 , said body formal by pressing together said particles at a pressure of from about 50 psi to about 6,000 psi. 
     
     
       6. The composite of  claim 5 , said particles being proud at a pressure of from about 100 psi to about 5,000 psi. 
     
     
       7. The composite of  claim 6 , said particles being pressed at a pressure of 2,000 psi. 
     
     
       8. The composite of  claim 1 , said particles being pressed-together. 
     
     
       9. A method of adsorbing a target compound comprising the steps of:
 providing a quantity of the composite of  claim 1 ; and  
 contacting said composite with a target compound selected from the group consisting of acids, alcohols, aldehydes, compounds containing an atom of P, S, N, Se, or Te, hydrocarbon compounds, and toxic metal compounds under conditions for adsorbing at least a portion of said target compound.  
 
     
     
       10. The method of  claim 9 , said particles being selected from the group consisting of MgO, CaO, TiO 2 , ZrO 2 , FeO, V 2 O 3 , V 2 O 3 , Mn 2 O 3 , FeO 3 , NiO, CuO, Al 2 O 3 , ZnO, Mg(OH) 2 , Ca(OH) 2 , Fe 2 (OH), Ni(OH) 2 , Cu(OH) 2 , Al(OH) 3 , Zn(OH) 2 , and mixtures thereof. 
     
     
       11. The method of  claim 10 , said particles being MgO. 
     
     
       12. The method of  claim 10 , said particles being CaO. 
     
     
       13. The method of  claim 9 , said target compound being in the form of a gas. 
     
     
       14. A method of removing an acid from a gas stream comprising the steps of:
   providing a quantity of self-sustaining bodies formed of agglomerated, nanocrystalline metal oxide particles selected from the group consisting of CaO, Ca(OH)   2   , ZnO, Zn(OH)   2   , and admixtures thereof, the particles have an average crystallite size of up to about  20  nm, said bodies having a total pore volume which is at least about  50   %  of the total pore volume of said particles prior to agglomeration thereof; and        passing a stream of acid-bearing gas into contact with said self-sustaining bodies under conditions for removing at least a portion of said acid from the gas stream.     
     
     
       15. The method of  claim 14 , wherein said acid contains, a sulfur atom. 
     
     
       16. The method of  claim 14 , said particles in the form of compressed-together bodies produced by pressing together said particles at a pressure of from about  50  psi to about  6 , 000  psi. 
     
     
       17. The method of  claim 14 , said bodies formed by pressing together said particles at a pressure of from about  500  psi to about  5 , 000  psi. 
     
     
       18. The method of  claim 14 , said bodies having a density of from about  0 . 2  to about  2 . 0  g/cm 3 . 
     
     
       19. The method of  claim 14 , said particles being CaO.