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Ammonia synthesis

  • US 4,792,441 A
  • Filed: 01/19/1988
  • Issued: 12/20/1988
  • Est. Priority Date: 01/19/1988
  • Status: Expired due to Fees
First Claim
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1. In the production and recovery of ammonia synthesis gas, the method which comprises:

  • providing a hydrocarbon vapor stream rich in methane and substantially free of sulfur compounds;

    (b) dividing said stream into a minor portion comprising less than 45% by volume of said stream and a major portion;

    (c) subjecting said minor portion to catalytic steam reforming at elevated temperature and pressure, thereby producing a primary reformate;

    (d) subjecting said major portion to oxidative reforming in admixture with the obtained primary reformate by catalytic reactionwith an oxygen-enriched air stream containing 30-35% oxygen by volume, thereby producing a secondary reformate comprised principally of hydrogen, nitrogen and carbon oxides and containing a minor amount of contaminants including methane and argon;

    the hydrogen content of said secondary reformate being less than that providing a 3;

    1 mol ratio of hydrogen to nitrogen in said secondary reformate;

    (e) subjecting said secondary reformate to a water gas shift reaction whereby contained carbon monoxide is converted to carbon dioxide and thereby also producing a further quantity of hydrogen, such that the H2 /N2 mol ratio in the shift reaction product is approximately 3;

    1;

    (f) removing carbon dioxide from the shift reacted secondary reformate by passing the same at superatmospheric pressure through a first bed of solid particulate adsorbent selective in retention of carbon dioxide, thereby producing a hydrogen-rich product effluent freed of carbonddioxide;

    (g) passing said hydrogen-rich effluent into and through a second bed of solid particulate adsorbent selective in retention of carbon monoxide and methane as opposed to hydrogen and nitrogen and recovering from said second bed a mixture of hydrogen and nitrogen in approximately 3;

    1 molar ratio and containing less than 25% of impurities on a dry basis.

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