Temperature-switched MAS NMR: A new method for time-resolved in situ studies of reaction steps in heterogeneous catalysis

• Published in: Chemical physics letters Vol. 229; no. 3; pp. 291 - 296
• Main Authors: Ernst, H., Freude, D., Mildner, T.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 28.10.1994
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/0009-2614(94)01045-5

The temperature of zeolite samples containing adsorbed methanol molecules was switched from room temperature to 500–600 K within 30–40 s by means of a laser beam. The catalytic reaction was monitored by 13C MAS NMR and 1H MAS NMR, the latter in steps of one second. A two-dimensional Fourier-transformation of the difference between the time-dependent and the equilibrium state of the system gives a good representation of reaction steps. For the methanol conversion it was found that the primarily formed C 3/C 4 alkanes are still involved in further reactions, whereas methane is an inert product under these conditions.