United States Patent Application: 0070274891
In the course of our many reports concerning the indirect conversion of Coal into more versatile hydrocarbons, we have once or twice made note of the fact that either plain Air or purified Oxygen, with or without the addition of Steam, can be utilized in the gasification, the partial oxidation, of Coal; which leads to the generation of a synthesis gas that, through various and long-known catalytic processes, can be condensed into hydrocarbon liquids.
Using Air for that initial gasification is more economical than using Oxygen - with the expensive, and costly to operate, equipment that separating and compressing Oxygen from the atmosphere requires.
However, due especially to Air's high Nitrogen content, it's use in Coal gasification leads to co-production of some, perhaps troublesome, compounds based on Nitrogen, including, for instance, Ammonia, "NH4".
Ammonia isn't really a bad thing to have, since, if recovered, it can, among other things, be used in the production of fertilizer - which is, as we understand it, among the desired products arising from China's extensive implementation and industrialization of Coal conversion technology.
However, along with the useful NH4, there are co-generated, in a Coal gasification process based on partial combustion with Air, various oxides of Nitrogen, often generically labeled as "NOX", where the "X" denotes a variable number of Oxygen atoms.
Those compounds are major components of "smog"; and, they are undesired.
Herein, we see that the French Company "Air Liquide", whose Coal gasification expertise we have previously documented for you, have, through some of their scientists in France, and via their US business center in Texas, developed a process wherein the Nitrogen Oxides, arising from a Coal syngas manufacturing process based on the economical use of Air, can be reclaimed and converted into the more useful NH3 Ammonia ion.
Comment follows excerpts from:
"US Patent Application 20070274891 - Purification of a Mixture of H2/CO by Catalysis of the NOx
Date: November, 2007
Inventor: Natacha Hait-Beraud, et. al., France
Assignee: Air Liquide, Houston, Texas
Abstract: The invention relates to a method for purifying a gas flow containing hydrogen (H2) and carbon monoxide (CO), in addition to at least one nitrogen oxide (NOx), as impurities. According to said method, the gaseous flow is brought into contact with at least one catalyst containing copper and/or palladium, ... in such a way as to eliminate at least part of the nitrogen oxide.
Claims: A method for purifying a gas stream containing hydrogen (H2) and carbon monoxide (CO), and further containing at least one nitrogen oxide (NOx) as impurities, in which the gas stream is contacted with at least one catalyst containing copper and/or palladium ... in order to remove at least part of the nitrogen oxide.
The method (wherein) the gas stream contains hydrogen (H2), carbon monoxide (CO), and methane (CH4).
(And, wherein) the nitrogen oxides are converted to water (H2O), O2, NH3, and/or N2.
Description: The invention relates to a method for purifying gas mixtures, particularly gas mixtures mainly containing hydrogen and carbon monoxide, commonly called H2/CO mixtures or "syngas", and, optionally, methane (CH4), which are polluted by impurities of the NOx type.
(Such) gas mixtures can be obtained in various ways (including) coal gasification.
(And) the Fischer-Tropsch synthesis has been used for several years to obtain hydrocarbons (from such gas mixtures).
In general, numerous metals can be used to catalyze the formation of hydrocarbons from CO and H2. Examples include the following metals: Ru, Ir, Rh, Ni, Co, Os, Pt, Fe, Mo, Pd, or Ag as explained by F. Fischer, H. Tropsch and (others).
(But) undesirable impurities include nitrogen oxides commonly called NOx (and include) N2O, NO, N2O3 (and) N2O5 (and, it is) indispensable to be able to remove them as efficiently as possible.
The solution of the invention is accordingly a method for purifying a gas stream containing at least one nitrogen oxide (NOx) as impurities, in which the gas stream is contacted with at least one catalyst containing copper or palladium ... in order to catalyze at least part of the ... nitrogen oxides (which are) converted to water (H2O), O2, NH3 and/or nitrogen."
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Thus, if we want to gasify Coal to provide the raw materials for "the Fischer-Tropsch synthesis", which will produce liquid hydrocarbons for us; and, we want to use less-expensive Air, instead of purified Oxygen, as one of the agents of gasification, then we can use the oxides of Nitrogen that are then co-produced to manufacture both commercially useful Oxygen and a raw material for fertilizer, among other things.
And, that would serve, through both the production of potentially-valuable commodities and the prevention of pollutant emissions, to make the total expense of converting abundant Coal into needed hydrocarbons, via indirect processes of gasification, even more cost-effective.