posted on 2020-03-10, 18:45authored byNikita Levin, Jozef Lengyel, Jan F. Eckhard, Martin Tschurl, Ueli Heiz
Mass-selected
Ta8O2+ cluster ions
catalyze the transformation of methane in a gas-phase ion trap experiment
via nonoxidative coupling into ethane and H2, which is
a prospective reaction for the generation of valuable chemicals on
an industrial scale. Systematic variation of the reaction conditions
and the isotopic labeling of methane by deuterium allow for an unambiguous
identification of a catalytic cycle. Comparison with the proposed
catalytic cycle for tantalum-doped silica catalysts reveals surprising
similarities as the mechanism of the C–C coupling step, but
also peculiar differences like the mechanism of the eventual formation
of molecular hydrogen and ethane. Therefore, this work not only supplies
insights into the mechanisms of methane coupling reactions but also
illustrates how the study of trapped ionic catalysts can contribute
to the understanding of reactions, which are otherwise difficult to
study.