J.I. Villegas

Classification and pattern recognition of acyclic octenes based on mass spectra

Two SIMCA models were developed for the classification of acyclic octene isomers, which only form a fraction of a very complex product mixture obtained, for example, from the transformation of 1-butene. The effects of spectral transformation, namely autocorrelation and logarithmic intensity ratios transforms, and (square-root) scaling of the octane isomers mass-spectral data were investigated. Both the spectral-features preprocessing methods and scaling were found to be vital for an adequate development and improvement of the classification models. The best SIMCA models were successfully applied on gas-chromatography-mass spectroscopy (GC-MS) analysis collected from the dimerization of 1-butene over heterogeneous catalysts in the liquid phase.

Isomerization of n-butane over Pt-modified mordenite zeolite catalysts: effect of Pt loadings and dealumination

Isobutane is an important raw material in the production of synthetic rubber and oxygenates for octane-boosting compounds. Highly acidic zeolites, such as mordenite, have been proposed as environmentally-friendly catalysts. Dealuminated and non-dealuminated mordenite zeolite catalysts (SiO 2 /Al 2 O 3 12.8) modified with 0.5, 1 and 2 wt-% of Pt were tested for the isomerization of n -butane. 0.5 wt-% Pt-MOR exhibited the highest isomerization efficiency (IE), e.g. defined as iC 4 /(C 3 +C 5 ) and the lowest deactivation at the conditions tested. Upon dealumination, the activity of the 0.5 wt-% Pt-modified mordenite zeolites decreased but the selectivity to isobutane was the highest. This is the combined effect of extra-framework Al and a less acidic catalyst. Calcination of dealuminated Pt-modified mordenite resulted in enhanced formation of micropores and there by increase in the initial conversion of n -butane.