Process for synthesizing molecular sieves

A process for synthesizing a molecular sieve having a three dimensional microporous framework structure and a framework composition represented by an empirical formula of:

• (ElwAlxPy′Siz)O2
• where El, Al, P and Si are framework elements present as tetrahedral oxide units, “w” is the mole fraction of El and has a value from zero to about 0.5, “x” is the mole fraction of Al and has a value from 0 to about 0.5, y′ is the mole fraction of P and has a value from greater than 0 to about 0.5, and “z” is the mole fraction of Si and has a value from 0 to about 0.98, w+x+y′+z=1, the process comprising providing a slurry of seed crystals at reaction conditions;
• adding to the slurry nutrients to provide;
• framework elements of the seed crystals thereby growing the seed crystals;
• carrying out the addition at a rate that essentially equals the crystal growth rate and for a time sufficient to produce the, molecular sieve.

A process for synthesizing a microporous molecular sieve having a three dimensional structure comprising a core molecular sieve and an outer molecular sieve, both molecular sieves having the same framework structure, the core molecular sieve having a composition represented by an empirical formula of

• (AlxSi1-x)O2
• where Al and Si are framework elements, present as tetrahedral oxide units, and x has a value from 0 to about 0.5;
• the process comprising providing a slurry of crystals of the core molecular sieve at reaction conditions;
• adding to the slurry nutrients to provide framework elements, thereby growing an outer molecular sieve over the seed crystals, the outer molecular sieve having the same framework structure as the core molecular sieve but the core and outer molecular sieve differing by at least one framework element, the outer molecular sieve having a composition represented by the empirical formula:
• (ElwAlxPySiz)O2
• where El, Al, P and Si are framework elements present as tetrahedral oxide units, “w” is the mole fraction of El and has a value from zero to about 0.5, “x” is the mole fraction of Al and has a value from 0 to about 0.5, “y” is the mole fraction of P and has a value from 0 to about 0.5, and “z” is the mole fraction of Si and has a value from 0 to about 1, w+x+y+z=1 and “y” and “z” are not simultaneously zero;
• carrying out the addition at a rate that essentially equals the growth rate of the outer molecular sieve and for a time sufficient to produce the molecular sieve.

A process for synthesizing a microporous molecular sieve having a three dimensional structure comprising a core molecular sieve and an outer molecular sieve, both molecular sieves having the same framework structure, the core molecular sieve having a composition represented by an empirical formula of:

• (ElwAlxPy′Siz)O2
• where El, Al, P and Si are framework elements present as tetrahedral oxide units, “w” is the mole fraction of El and has a value from zero to about 0.5, “x” is the mole fraction of Al and has a value from 0 to about 0.5, y′ is the mole fraction of P and has a value from greater than 0 to about 0.5, and “z” is the mole fraction of Si and has a value from 0 to about 0.98, w+x+y′+z=1, the process comprising providing a slurry of crystals of the core molecular sieve at reaction conditions;
• adding to the slurry nutrients to provide framework elements thereby growing an outer molecular sieve over the crystals, the outer molecular sieve having the same framework structure as the core molecular sieve, but the core and outer molecular sieve differing by at least one framework element, the outer molecular sieve having a composition represented by the empirical formula:
• (ElwAlxPySiz)O2
• where El, Al, P and Si are framework elements present as tetrahedral oxide units, “w” is the mole fraction of El and has a value from zero to about 0.5, “x” is the mole fraction of Al and has a value from 0 to about 0.5, “y” is the mole fraction of P and has a value from 0 to about 0.5, and “z” is the mole fraction of Si and has a value from 0 to about 1, w+x+y+z=1 and “y” and “z” are not simultaneously zero;
• carrying out the addition at a rate that essentially equals the growth rate of the outer molecular sieve and for a time sufficient to produce the molecular sieve.