Structure directing agent for improved synthesis of zeolites

1. A method of preparing a SSZ-39 AEI zeolite, comprising:

providing a precursor for 3,5-dimethyl-N,N-dimethylpiperidinium hydroxide;

treating the precursor to provide an intermediate 3,5-dimethyl-N,N-dimethylpiperidinium salt that, when subsequently treated to form the 3,5-dimethyl-N,N-dimethylpiperidinium hydroxide, has a content of trans isomer of the 3,5-dimethyl-N,N-dimethylpiperidinium hydroxide in a range from greater than 25% up to 80% and a content of the cis isomer from less than 75% to 20%;

contacting under crystallization conditions a mixture of sources of an oxide of silicon and faujasite, one or more alkali metal hydroxide or alkaline earth metal hydroxide, water, and a structure-directing agent comprising the 3,5-dimethyl-N,N -dimethylpiperidinium hydroxide having the content of the trans isomer of the 3,5-dimethyl-N,N-dimethylpiperidinium hydroxide in the range from greater than 25% up to 80% and a content of the cis isomer from less than 75% down to 20%; and

calcining the mixture to form a SSZ-39 AEI zeolite,

wherein the precursor is 3,5-dimethyl pyridine, or N-methyl-3,5-dimethylpiperidine, or 3,5-dimethylpiperidine.

2. The method of claim 1 wherein the treating comprises one or more of chemical reduction, non-catalytic hydrogenation, catalytic hydrogenation in the absence of water, selective crystallization, and distillation.

3. The method of claim 1 wherein the ratio of the trans isomer to the cis isomer of the 3,5-dimethyl-N,N-dimethylpiperidinium hydroxide is controlled by selective isolation of 3,5-dimethyl piperidine following hydrogenation of 3,5-dimethylpyridine, and subsequent methylation of the 3,5-dimethylpiperidene to form the 3,5-dimethyl-N,N-dimethylpiperidinium cation, which is subsequently paired with a hydroxide anion.

4. The method of claim 1 wherein the oxide of silicon is one or a combination of two or more of a silicate, a silica hydrogel, silicic acid, fumed silica, colloidal silica, a tetra-alkyl orthosilicate, and a silica hydroxide.

5. The method of claim 1 wherein the contacting further comprises addition to the faujasite of one or a mixture of two or more of an aluminate, alumina, an aluminum colloid, aluminum oxide coated on silica sol, hydrated Al(OH) 3 , AlCl 3 and Al 2 (SO 4 ) 3.

6. The method of claim 1 wherein the precursor is 3,5-dimethyl pyridine, and the treating comprises a catalytic reduction to form a mixture of cis- and trans-3,5-dimethylpiperidine.

7. The method of claim 1 wherein the combining under crystallization conditions comprises stirring the mixture at room temperature, and the calcining comprises heating the mixture to an elevated temperature.

8. A method of making Cu-SSZ-39 AEI zeolite, comprising:

(a) providing a SSZ-39 AEI zeolite made according to claim 1 ;

(b) replacing at least a portion of alkali metal cation or alkaline earth metal cation remaining in the SSZ-39 AEI zeolite with a Cu+2 cation, to form Cu-SSZ-39 AEI zeolite.