A technique for simultaneous in situ MAS NMR and on-line gas chromatographic studies of hydrocarbon conversions on solid catalysts under flow conditions

A new technique is introduced allowing simultaneous in situ MAS NMR investi gations of hydrocarbon conversions on solids under flow conditions and on-l ine gas chromatography. For adsorption of methanol on zeolite HBeta, equal amounts of adsorbed molecules were determined by both analytical methods. S tudying the synthesis of methyl tertiary-butyl ether (MTBE) on zeolite HBet a using an MAS NMR rotor reactor, a constant yield of MTBE of Y-mtbe = 27% was obtained up to a weight hourly space velocity of 1.4 h(-1). The variati on of the reaction temperature led to a simultaneous change of the C-13 MAS NMR signals of isobutoxy species and of the yield of MTBE determined by on -line gas chromatography which indicates that isobutoxy species act as chem ically active compounds. In this first application, the new in situ techniq ue has demonstrated its advantage for a simultaneous investigation of compo unds with a long residence time on the catalyst surface and of compounds ra pidly leaving the catalyst surface.