Abstract
The thermochemical, crystallographic, morphologic and catalytic properties of a synthetic tetramethylammonium (TMA) offretite and its ammonium and hydrogen derivative forms have been investigated. TMA offretite crystallizes as small irregular particles (0.5μ × 1.5μ) in contrast to the more elongated crystals of natural and synthetic erionite. Thermal decomposition of TMA ions (probably located in the large intracrystalline pores along the c crystallographic axis) occurs near 483 °C. The resulting catalyst sorbs 7.8 wt % cyclohexane, 8.8 wt% n-hexane and 16.5 wt % water. Room temperature ion exchange of the parent TMA offretite with 0.1 N (NH 4) 2SO 4 yields an ammonium derivative with one potassium per unit cell trapped in a cancrinite cage or hexagonal prism. Conversion of NH 4-offretite to the acid form requires a temperature 100 °C higher than NH 4Y. Acid offretite shows significant activity for the catalytic cracking of n-hexane.
Published Version
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