DDR type zeolites with stabilized adsorption
AssigneeExxonMobil Research and Engineering Company
InventorsPeter I. Ravikovitch, Barbara Carstensen, Charanjit S. Paur, Ivy D. Johnson, Harry W. Deckman
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Abstract
Methods are provided for forming zeolite crystals suitable for gas phase separations with transport characteristics that are stable over time. The zeolitic materials and/or corresponding methods of synthesis or treatment described herein provide for improved stability in the early stages of process operation for some types of gas phase separations. The methods allow for synthesis of DDR type zeolites that have reduced contents of alkali metal impurities. The synthetic methods for reducing the non-framework alkali metal atom or cation impurity content appear to have little or no impact on the DDR crystal structure and morphology.
Claims10
A method for performing a gas separation, comprising:
- contacting an adsorbent or membrane comprising DDR-type zeolite crystals with an input gas stream containing a first component and a second component to form a first gas stream enriched in the first component relative to the input gas stream;
- and
- collecting a second gas stream enriched in the second component relative to the input gas stream,
- wherein the DDR-type zeolite crystals are synthesized using a synthesis mixture having an alkali metal to silica ratio of at least about 0.01, the adsorbent being comprised of crystals with an alkali metal impurity content of about 0.05 wt % or less;
- wherein the DDR-type zeolite crystals as synthesized have an alkali metal impurity content of at least about 0.1 wt %, the alkali metal impurity content being reduced prior to contacting the adsorbent by exposing the DDR-type zeolite crystals to an alkali metal impurity removal process.
Dependencies are inferred from the claim text.