Production of crystalline zeolites

A process for producing crystalline zeolite TPZ-12, which comprises maintaining a starting mixture at a temperature of at least 80.degree. C. for a period sufficient to produce zeolite crystals, said starting mixture consisting of

• (a) a substance capable of yielding silica under the reaction conditions,
• (b) a water-soluble alkali metal compound,
• (c) water, and
• (d) a diammonium compound represented by the following general formula ##STR9## wherein R.sub.1 and R.sub.2 are identical or different and each represents an alkyl group having 1 to 4 carbon atoms, p and q are identical or different and each represents an integer of 4 or 5, n is 4, 5 or 6, and y represents an anion having a valence of m, and optionally,
• (e) a substance capable of yielding alumina under the reaction conditions,
• in the quantities represented by the following expressions
• 1.ltoreq.[ SiO.sub.2 ]/[Al.sub.2 O.sub.3 ]
• 1.times.10.sup.-4 .ltoreq.[A]/([Si]+[Al]).ltoreq.1
• 1.times.10.sup.-4 .ltoreq.[OH]/([Si]+[Al]).ltoreq.0.5
• 5.ltoreq.[H.sub.2 O]/([Si]+[Al]).ltoreq.100
• 1.times.10.sup.-5 .ltoreq.[OH]/[H.sub.2 O].ltoreq.1.times.10.sup.-1
• wherein
• [SiO.sub.2 ] represents the amount in moles of the substance capable of yielding silica under the reaction conditions calculated as SiO.sub.2,
• [Al.sub.2 O.sub.3 ] represents the amount in moles of the substance capable of yielding alumina under the reaction conditions calculated as Al.sub.2 O.sub.3,
• [Si] represents the amount in moles of the substance capable of yielding silica under the reaction conditions calculated as Si,
• [Al] represents the amount in moles of the substance capable of yielding alumina under the reaction conditions calculated as Al,
• [A] represents the amount in moles of the diammonium compound,
• [H.sub.2 O] represents the amount in moles of water, and
• [OH] represents the total amount in moles of the alkali metal compound and the diammonium compound calculated as OH.