Reactions of Clay Volatiles with n-Alkanes

Lisa Heller-Kallai, Irena Miloslavski and Zeev Aizenshtat
Institute of Earth Sciences, The Hebrew University of Jerusalem Jerusalem 91904, Israel
Casali Institute of Applied Chemistry The Hebrew University of Jerusalem, Jerusalem 91904, Israel

Abstract: Volatiles formed on heating clay minerals contain a variety of cations and anions and are highly reactive. Gas chromatograph-mass spectrometer analysis of long-chain n-alkanes exposed to such volatiles showed that some decomposition occurred even < 250°C. Reactions with anions donated by the volatiles led to compounds containing atoms other than C and H, e.g., Cl. The products obtained from n-alkanes heated in a stream of clay volatiles to 500°C resembled those produced by corresponding alkane-clay mixtures heated to 250°C. At higher temperatures contact between the alkanes and montmorillonite or halloysite led to changes in the assemblages formed, whereas kaolinite or sepiolite had no effect. Thus, the first reactions that occurred when clays were heated with n-alkanes were apparently induced by the volatiles; at higher temperatures catalysis due to direct contact came into play with some of the clay minerals.

Key Words: Alkane • Catalysis • Clay volatiles • Gas chromatography • Halloysite • Kaolinite • Mass spectrometry • Montmorillonite • Sepiolite

Clays and Clay Minerals; October 1989 v. 37; no. 5; p. 446-450; DOI: 10.1346/CCMN.1989.0370508
© 1989, The Clay Minerals Society
Clay Minerals Society (www.clays.org)