California Institute of Technology

George R Gavalas

Suk Woo Nam

Satish S Tamhankar

George C Hsu

Pramod K Sharma

Gerald E Voecks

Soojin Kim

Shaocong Jiang

Partha S Ganguli

Sarkis H Kalfayan

Constantin E Megiris

Maria Flytani-Stephanopoulos

Michael Tsapatsis

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.

Method for forming improved H.sub.2 -permselective oxide membranes using

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.4-n where n is 1, 2 or 3; and the second reactant stream contains water vapor and oxygen. In still another embodiment the first reactant stream containing a first reactant selected from the group consisting of Cl.sub.3 SiOSiCl.sub.3, Cl.sub.3 SiOSiCl.sub.2 OSiCl.sub.3, and mixtures thereof and the second reactant stream contains water vapor. In still another embodiment, membrane formation is carried out by an alternating flow deposition method. This involves a sequence of cycles, each cycle comprising introduction of the halide-containing stream and allowance of a specific time for reaction followed by purge and flow of the water vapor containing stream for a specific length of time. In all embodiments the nonporous layers formed are selectively permeable to hydrogen.

Method for forming H2-permselective oxide membranes

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.

Calcium impregnation of coal enriched in CO.sub.2 using high-pressure

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.

Synthesis of SiO.sub.2 membrane on porous support and method of use of

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. The presence of iron or aluminum maintains the Group IB, IIB or VIIB metal in its oxidized state. Presence of molybdenum results in eutectic formation at sulfidation temperature and improves the efficiency of the sorbent.

High temperature regenerative H.sub.2 S sorbents

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.

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Altadena, CA, United States of America

George R Gavalas