Method of producing binderless zeolite extrudates
AssigneeW. R. Grace & Co.
InventorDarrell E. Hildebrandt
Life of this patent
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Abstract
An improved method of making binderless zeolite sieve extrudates. After extruding a mixture containing about 40-60% zeolites with the remainder being a metakaolin clay that has mixed with it about 90-120% of the stoichiometric amount of sodium hydroxide to convert the clay to a zeolite, the extruded particles are allowed to dry age under dry, bulk conditions in a container during which time autogeneous heat develops and most of the clay is converted to the zeolite. A further heat treatment in a dilute caustic aqueous solution may be used to insure complete crystallization with subsequent washing and calcination to produce an adsorbent product.
Claims8
In a process of producing binderless zeolite sieve extrudates containing at least Type A Zeolite from clay and a synthetic zeolite, said extrudates having a higher adsorption capacity, a faster adsorption rate, improved selectivity, and improved attrition resistance, said process comprising
- (a) forming an extrudable mixture of
- (i) a synthetic zeolite,
- (ii) metakaolin clay,
- (iii) sodium hydroxide solution
- said clay comprising about 40-60% by weight of the total weight of the clay and the zeolite on a dry basis and the amount of sodium hydroxide being in the range of about 90-120% of the stoichiometric amount to convert the clay to a zeolite;
- (b) extruding the mixture of step (a) to form extrudates;
- (c) aging the extrudates;
- (d) treating the extrudates with a dilute solution of sodium hydroxide at an elevated temperature to complete the crystallization of the aged extrudates;
- (e) washing the extrudates;
- and
- (f) recovering the washed extrudates and dry calcining them whereby they can be used as selective adsorbents;
- the improvement comprising aging the extrudates in step (c) under dry, bulk storage in a container whereby autogenous heat develops to crystallize a substantial portion of the clay.
Dependencies are inferred from the claim text.