NOVELTY - Preparation of porous crystalline material ITQ-12 includes preparing a reaction mixture comprising water source, source of an oxide of tetravalent element(s), and specific organic directing agent; maintaining the reaction mixture under conditions sufficient to form crystals of crystalline material; and recovering crystalline material having ITQ-12 framework structure from the reaction mixture.    USE - For preparing porous crystalline material ITQ-12 useful in gas separation, e.g. separation of propane and propene mixture.    ADVANTAGE - The reaction is fast, does not involve the release of proton, does not require the presence of inorganic base and can be conducted in benign solvents, such as ethanol. The ITQ-12 can be prepared in pure form with little or no detectable impurity crystal phases and has an X-ray diffraction pattern which is distinguished from the patterns of other known as-produced or thermally treated crystalline materials by specified lines.    DETAILED DESCRIPTION - Preparation of porous crystalline material ITQ-12 having a molar relationship (m)X2O3:YO2 includes preparing a reaction mixture comprising water source, source of an oxide of tetravalent element(s), optionally source of an oxide of trivalent element(s), and organic directing agent of formula (I) for directing formation of ITQ-12 molecular sieve; maintaining the reaction mixture under conditions sufficient to form crystals of crystalline material; and recovering crystalline material having ITQ-12 framework structure from the reaction mixture.    X=trivalent element(s);    Y=tetravalent element(s);    m=0-0.2, preferably 0;    n=1-3; and    Q=anion.    INDEPENDENT CLAIMS are included for:    (1) conversion of feedstock comprising organic compounds by reacting feedstock with a catalyst comprising active form of crystalline material; and    (2) separation of mixture comprising at least two gases, e.g. propane and propene, by selectively adsorbing at least one of gases using crystalline material.