Synthesis of molecular sieves having MWW framework structure

A method of making a MWW family molecular sieve material comprising the steps of:

• (a) preparing a solution comprising an alkali or an alkaline earth metal (M) cation and water,
• (b) preparing a precipitated aluminosilicate comprising a combined source of both aluminum (Al) and silicon (Si), said precipitated aluminosilicate having a composition in terms of mole ratios within the following ranges:
• SiO2/Al2O3=10 to 600;
• (c) combining said solution and said precipitated aluminosilicate to form a reaction mixture having a composition in terms of mole ratios within the following ranges:
• H2O/SiO2=5 to 15;
• OH−/SiO2=0.001 to 2;
• and
• M/SiO2=0.001 to 2;
• (d) afterward adding an organic structure-directing agent (R) to said reaction mixture of step (c) so that it has a composition of structure-directing agent (R) in terms of mole ratios within the range:
• R/SiO2=0.001 to 0.5;
• (e) crystallizing said reaction mixture of step (d) under crystallization conditions of a temperature of from about 90° C. to about 175° C. and a time for less than 90 hours to form a resulting mixture comprising crystals of said MWW family molecular sieve material and less than about 10 wt. % of impurity crystals having non-MWW framework structure based on the total weight of said MWW family molecular sieve material in said reaction mixture, as identified by X-ray diffraction;
• and
• (f) recovering at least a portion of said crystals of said MWW family molecular sieve material from said resulting mixture of step(e) as an as-synthesized MWW family molecular sieve material having an X-ray diffraction pattern including d-spacing maxima at 12.4±0.25, 6.9±0.15, 3.57±0.07 and 3.42±0.07 Angstroms.