Low pressure ammonia synthesis utilizing adsorptive enhancement
First Claim
1. A process for synthesizing ammonia, comprising:
- providing a vessel containing an adsorbant that adsorbs ammonia in preference to H2 and N2; and
bringing H2 and N2 together in the vessel under conditions where the H2 and the N2 react at a rate sufficient to bring about significant conversion to ammonia within the vessel;
wherein ammonia is adsorbed by the adsorbant simultaneously with the reaction and the adsorbant captures ammonia and thereby enhances the net conversion of H2 and N2 to ammonia.
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Abstract
One aspect of the invention relates to a process for synthesizing ammonia from hydrogen and nitrogen in which an adsorbant is provided to adsorb ammonia as it is being produced. Adsorption of the product drives the ammonia synthesis reaction and allows the process to be carried out at pressures where the gas phase equilibrium conversion is too low for a conventional system to be practical. The invention is applicable to both small and large scale ammonia synthesis. A small scale ammonia synthesis plant can be a stationary or vehicle-mounted plant used to supply reducing agent for selective catalytic reduction of NOx in diesel exhaust. Ammonia can be desorbed from the adsorbant, extracted from the adsorbant, or stored and transported in its adsorbed state.
26 Citations
64 Claims
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1. A process for synthesizing ammonia, comprising:
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providing a vessel containing an adsorbant that adsorbs ammonia in preference to H2 and N2; and
bringing H2 and N2 together in the vessel under conditions where the H2 and the N2 react at a rate sufficient to bring about significant conversion to ammonia within the vessel;
wherein ammonia is adsorbed by the adsorbant simultaneously with the reaction and the adsorbant captures ammonia and thereby enhances the net conversion of H2 and N2 to ammonia. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. An ammonia synthesis plant, comprising:
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a reaction vessel containing an adsorbant for ammonia. a nitrogen source configured to supply the reaction vessel with nitrogen; and
a hydrogen source configured to supply the reaction vessel with hydrogen;
wherein the reaction vessel is configured to bring about reaction of the hydrogen and the nitrogen to produce ammonia and the adsorbant is configured to adsorb the ammonia. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54)
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55. A method of enhancing the single pass conversion in an ammonia synthesis plant comprising:
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placing an ammonia adsorbant inside the plant to adsorb ammonia as it is produced; and
intermittently inducing desorption from the adsorbant to regenerate the adsorbant. - View Dependent Claims (56, 57, 58)
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59. A process of separating gaseous ammonia from other gasses, comprising:
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adsorbing the ammonia on an adsorbant comprising an effective amount of Chabazite cation exchanged with lithium; and
inducing desorption of the ammonia. - View Dependent Claims (60)
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61. An ammonia synthesis plant, comprising:
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a plurality of ammonia synthesis reactors comprising an adsorbant that adsorbs ammonia synthesized in the reactors;
a mobile framework configured to hold the reactors and move them in sequence through a plurality of positions; and
one or more couplings adapted to provide a feed comprising hydrogen and nitrogen to the reactors in a subset of the positions;
wherein a subset is at least one, but less than all;
whereby the mobile framework is adapted to move the reactors in and out of position to receive the feed and at any given time less than all of the reactors are configured to receive the feed. - View Dependent Claims (62, 63)
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64. A method of synthesizing ammonia, comprising:
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providing a plurality of ammonia synthesis reactors comprising an adsorbant for ammonia; and
providing an indexing system that moves the reactors whereby each of the reactors alternates through a set of positions and in one or more of the positions the reactors receive a feed comprising hydrogen and nitrogen in one or more others of the positions the reactors receive a flow of inert gas;
wherein the feed reacts in the reactors to produce ammonia that adsorbs on the adsorbant; and
the ammonia desorbs and is carried away by the flow of inert gas, whereby the adsorbant is regenerated.
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Specification