Air Products and Chemicals, Inc.

Alejandro L Cabrera

John F Kirner

John N Armor

Ronald Pierantozzi

Robert A Miller

Charles G Coe

Thomas R Gaffney

Thomas Stephen Farris

James W Brockington

A process is provided for making a modified carbon molecular sieve which is suitable for separating gases having different adsorption rates on the sieve. The process involves modifying a starting sieve support having a majority of micropores with an effective pore size of about 4.5 to 8 angstroms, with a two-step process in which the sieve is contacted with two different volatile carbon-containing organic compounds, preferably hydrocarbons, which have different molecular dimensions. The compound used in the first step is larger than that in the second step, so that the pore openings of the micropores of the support are narrowed successively in two distinct steps without filling the micropores themselves. The invention also discloses an improved carbon molecular sieve and the separation of gases, such as oxygen from nitrogen, by the use of this improved adsorbent.

Modified carbon molecular sieves for gas separation

A process is provided for making a modified carbon molecular sieve which is suitable for separating gases having different adsorption rates on the sieve. The process involves modifying a starting sieve support having a majority of micropores with an effective pore size of about 4.5 to 20 angstroms, with a two-step process in which the sieve is contacted with two different concentrations of a volatile carbon-containing organic compound, preferably a hydrocarbon. The concentration of the carbon-containing compound used in the first step is larger than that in the second step, so that the pore openings of the micropores of the support are narrowed successively in two distinct steps without filling the micropores themselves. The invention also discloses an improved carbon molecular sieve and the separation of gases, such as oxygen from nitrogen, by the use of this improved adsorbent.

Modified carbon molecular sieve adsorbents

The surface properties of iron or ferrous alloy are improved by borosiliconizing the surface by contact with a stream of reducing gas containing hydrogen, optionally with an inert gas, to which a gaseous halide or hydride of boron and silicon have been added, either together or sequentially. The temperature of treatment is elevated, e.g. above 350.degree. C., but below 1200.degree. C. Diffusion coatings of both boron and silicon are formed in the ferrous surface. Typical surces of boron and silicon inlude boron trichloride, diborane and silane.

Gas phase borosiliconization of ferrous surfaces

Silicon carbide protective films are produced on the surface of metallic or metal-impregnated substrates. A silicide or silicon diffusion coating is initially formed on the surface of the substrate, and subsequently said surface is treated with a gas stream which is reducing to the coating and substrate and contains a gaseous carbon source at a temperature greater than 500.degree. C.

Process for preparing sic protective films on metallic or metal

A silicon diffusion coating is formed in the surface of a metal article by exposing the metal article to a reducing atmosphere followed by treatment in an atmosphere of 1 ppm to 100% by volume silane, balance hydrogen or hydrogen inert gas mixture. Hydrogen with a controlled dew point is utilized as a surface preparation agent and diluent for the silane.

Method of producing silicon diffusion coatings on metal articles

A process for bright annealing of chromium containing alloys such as stainless steels in an atmosphere of nitrogen and hydrogen containing controlled additions of an inhibitor as described in U.S. Pat. No. 4,334,938 wherein at least one element provided at the surface of the article being annealed in an amount such that it is oxidized in preference to the chromium in said article, whereby nitrogen uptake is inhibited and dulling of the metal surface by formation of a film containing chromium oxide is avoided.

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Fogelsville, PA, United States of America

Alejandro L Cabrera