Patent ID: 7785554

Claim:
A process for manufacturing a silicoaluminophosphate molecular sieve comprising at least one intergrown phase of AEI and CHA framework types, said process comprising the steps of: (a) combining at least one silicon source, at least one phosphorus source, at least one aluminum source, and at least one structure-directing-agent (R) to form a mixture; and (b) treating said mixture at crystallization conditions sufficient to form said silicoaluminophosphate molecular sieve, wherein the mixture prepared in step (a) has a molar composition of: (n)SiO 2 /Al 2 O 3 /(m)P 2 O 5 /(x)R/(y)H 2 O wherein n ranges from about 0.005 to about 0.6, m ranges from about 0.6 to about 1.2, x ranges from less than 1, and y ranges from about 10 to about 40; wherein the crystallization process comprises at least two stages, wherein in the first stage the synthesis mixture is heated under agitation so as to raise its temperature at a rate of at least 8° C./hour to a first temperature of about 99° C. to about 150° C., followed by maintaining the temperature of the synthesis mixture with the agitation being continued for a time from 0.5 or more hours to form an intermediate product mixture containing a slurry of the precursor material, the intermediate product mixture then heated in the second stage so as to raise its temperature at a rate of at least 8° C./hour to a second temperature from about 150° C. to about 220° C.; and wherein the yield of silicoaluminophosphate molecular sieve is at least 0.5 wt. % higher than the yield obtained with a synthesis mixture having a template to alumina molar ratio of 1 or higher.