Variable kinetic parameters for catalytic reactions of isobutane over zeolites

Abstract

Novel methodologies including wavelet shrinkage denoising techniques and time-varying linear flexible least squares (TVFLS) are used to determine kinetic rate parameters from the raw data of Le Minh (2005) and Le Minh and Brown (2006) obtained from low-pressure, steady-state, temperature programmed catalysis. These methodologies are applied to the raw mass spectral abundances from temperature-programmed isobutane conversion into isobutene and propene over the four pure zeolites: ZSM-5 (30), ZSM-5 (80), mordenite and ferrierite, and over modified ZSM-5 (30) with iron and antimony. Variations in rates are a consequence of isobutane cracking and dehydrogenation, isobutene and propene dimerization and desorption reaction pathways. Multiple ranges of accurate activation energies and pre-exponential factors validate the effectiveness of denoising the data by using the weighted averages of Daubechies Least Asymmetric wavelet families and then applying TVFLS.