Patents by Inventor George R. Gavalas

George R. Gavalas has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5503873
    Abstract: A method of forming inorganic membranes which are highly selective to permeation of hydrogen by temporarily forming a carbon barrier in the pores of a porous substrate, followed by chemical deposition of SiO.sub.2, B.sub.2 O.sub.3, TiO.sub.2, Al.sub.2 O.sub.3 and mixtures thereof in the pores, followed by removal of the carbon barrier. It has been demonstrated that the permeation selective layers thusly formed by this invention have a five fold increase in permeance over such layers made by a similar method but without forming a temporary carbon barrier in the pores of the porous substrate, and removal of the carbon-barrier after establishment of the oxide membrane. Some suitable porous substrate are Vycor.TM. glass or Al.sub.2 O.sub.3.
    Type: Grant
    Filed: June 30, 1994
    Date of Patent: April 2, 1996
    Assignee: California Institute of Technology
    Inventors: George R. Gavalas, Shaocong Jiang
  • Patent number: 5453298
    Abstract: Methods of forming permselective oxide membranes that are highly selective to permeation of hydrogen by chemical deposition of reactants in the pore of porous tubes, such as Vycor.TM. glass or Al.sub.2 O.sub.3 tubes. The porous tubes have pores extending through the tube wall. The process involves forming a stream containing a first reactant of the formula RX.sub.n, wherein R is silicon, titanium, boron or aluminum, X is chlorine, bromine or iodine, and n is a number which is equal to the valence of R; and forming another stream containing water vapor as the second reactant. Both of the reactant streams are passed along either the outside or the inside surface of a porous tube and the streams react in the pores of the porous tube to form a nonporous layer of R-oxide in the pores. The membranes are formed by the hydrolysis of the respective halides. In another embodiment, the first reactant stream contains a first reactant having the formula SiH.sub.n Cl.sub.
    Type: Grant
    Filed: April 1, 1994
    Date of Patent: September 26, 1995
    Assignee: California Institute of Technology
    Inventors: George R. Gavalas, Suk Woo Nam, Michael Tsapatsis, Soojin Kim
  • Patent number: 4964881
    Abstract: Methods are described for impregnating coal with calcium carbonate by utilizing an aqueous phase ionic reaction between calcium acetate, calcium hydroxide, and water with CO.sub.2 contained within the coal. The coal is enriched in CO.sub.2 by contacting it with CO.sub.2 at high pressure, in either a continuous or pulsed mode. The inclusion of CO.sub.2 in the coal during the process does not involve evacuating the coal and subsequently absorbing CO.sub.2 onto the coal as in prior methods. Rather, the coal is treated with carbon dioxide at high pressure in a practical and viable approach. The impregnation of coal by calcium compounds not only reduces sulfur emissions by effectively tying up the sulfur as calcium sulfide or sulfate, but also increases the gasification or combustion rate. The invention also encompasses the use of other Group IIA elements, as well as the coal products resulting from the methods of treatment described.
    Type: Grant
    Filed: February 13, 1989
    Date of Patent: October 23, 1990
    Assignee: The California Institute of Technology
    Inventors: Pramod K. Sharma, Gerald E. Voecks, George R. Gavalas
  • Patent number: 4902307
    Abstract: A method for lining a porous tube (5) with a film (11) of SiO.sub.2 is described. The treated tube may be used to separate hydrogen from reaction mixtures such as those resulting from the water-gas shift reaction or the catalytic decomposition of hydrogen sulfide.
    Type: Grant
    Filed: November 18, 1988
    Date of Patent: February 20, 1990
    Assignee: California Institute of Technology
    Inventors: George R. Gavalas, Constantin E. Megiris
  • Patent number: 4729889
    Abstract: Efficient, regenerable sorbents for removal of H.sub.2 S from high temperature gas streams comprise porous, high surface area particles. A first class of sorbents comprise a thin film of binary oxides that form a eutectic at the temperature of the gas stream coated onto a porous, high surface area refractory support. The binary oxides are a mixture of a Group VB or VIB metal oxide with a Group IB, IIB or VIII metal oxide such as a film of V-Zn-O, V-Cu-O, Cu-Mo-O, Zn-Mo-O or Fe-Mo-O coated on an alumina support. A second class of sorbents consist of particles of unsupported mixed oxides in the form of highly dispersed solid solutions of solid compounds characterized by small crystallite size, high porosity and relatively high surface area. The mixed oxide sorbents contain one Group IB, IIB or VIIB metal oxide such as copper, zinc or manganese and one or more oxides of Groups IIIA, VIB or VII such as aluminum, iron or molybdenum.
    Type: Grant
    Filed: March 29, 1985
    Date of Patent: March 8, 1988
    Assignee: California Institute of Technology
    Inventors: Maria Flytani-Stephanopoulos, George R. Gavalas, Satish S. Tamhankar
  • Patent number: 4081250
    Abstract: A method of chlorinolysis of coal in an organic solvent at a moderate temperature and atmospheric pressure has been proven to be effective in removing sulfur, particularly the organic sulfur, from coal. Chlorine gas is bubbled through a slurry of moist coal in chlorinated solvent. The chlorinated coal is separated, hydrolyzed and then dechlorinated. Preliminary results of treating a high sulfutr (4.77%S) bituminous coal show that up to 70% organic sulfur, 90% pyritic sulfur and 76% total sulfur can be removed. The treated coal is dechlorinated by heating at 500.degree. C. The presence of moisture helps to remove organic sulfur.
    Type: Grant
    Filed: August 27, 1976
    Date of Patent: March 28, 1978
    Assignee: California Institute of Technology
    Inventors: George C. Hsu, George R. Gavalas, Partha S. Ganguli, Sarkis H. Kalfayan