III International Conference

PP-I-31According to the 13 C MAS NMR data (Figure 1) two parallel reactions occurs: (1) themigration of 13 C-label in the n-butane molecule from methyl into methylene group and (2)more slow process of n- into isobutane isomerization.time25 20 15ppmFigure. 1The analysis of the mass-spectra of butanes formed from n-butane- 13 C on Cs 2.5 H 0.5 PWO 40in the absence and in the presence of CO allows to conclude that the migration of 13 C- labelsproceeds via monomolecular mechanism, whereas bimolecular pathway is prevalent for the n-butane isomerization into isobutane, even in the presence of CO.The in situ 13 C MAS NMR study of the kinetics of n-butane conversion onCs 2.5 H 0.5 PWO 40 revealed that both the migration of 13 C-label and isomerization into isobutaneproceeds with the similar activation energy ca 85 kJ mol -1 , presuming the hydride-shiftreaction between alkanes and carbenium ions to be the common rate determining step of thesereactions.References1. Adeeva, V.; Lei, G. D.; Sachtler, W. M. H. Appl. Catal. A 1994, 18, L11.2. Luzgin, M. V.; Arzumanov, S. S.; Shmachkova, V. P.; Kotsarenko, N. S.; Rogov, V. A.;Stepanov, A. G. J. Catal. 2003, 220, 233.3. Luzgin, M. V.; Stepanov, A. G.; Arzumanov, S. S.; Rogov, V. A.; Parmon, V. N.; Wang, W.;Hunger, M.; Freude, D. Chem. Eur. J. 2006, 12, 457.4. Miyaji, A.; Echizen, T.; Li, L.; Suzuki, T.; Yoshinaga, Y.; Okuhara, T. Catal. Today 2002, 74,291.5. Ma, Z.; Hua, W.; Ren, Y.; He, H.; Gao, Z. Appl. Catal. A 2003, 256, 243.64