Isomerization of n-Butane on Pd-SZ Catalyst. Effect of Reaction Conditions
Доклады на конференциях
Nowadays, n-butane isomerization on Pt-modified sulfated zirconia catalysts (Pt-SZ) is intensively studied. Due to the unique acid–base properties sulfated zirconia (SZ) may have significant potential for use in industrial processes, provided that high activity of the catalysts shall be ensured . It was reported in [1, 2] that high activity and stability of Pd-modified catalyst Pd-SZ can significantly improve the process of n-butane isomerization. The prospects for industrial implementation of the process require further in-depth kinetic studies; this was the main goal of the present work. Isomerization of n-butane over Pd–SZ catalyst (Pd load 0.35 wt.%) was studied in a flowtype fixed-bed reactor within 5÷25% n-butane conversion range. Catalyst preparation procedure, its physical–chemical characteristics and details of the lab-scale setup have been specified in . The influence of parameters on the reaction rates and products selectivity was investigated by varying n-butane WHSV 1.3-11.1 h-1, temperature 125-160°C, molar ratio H2/C4 0.1-1.0, and pressure 6–25 bar. For kinetic studies, the catalyst granules were crushed and sieved as 0.25÷0.5 mm fractures. To verify possible subsequent transformations of isobutane on Pd-SZ catalyst at n-butane isomerization conditions, additional experimental studies of pure iso-butane conversion were performed. No significant catalyst deactivation was observed during the long-time operation on-stream at standard experimental conditions: at a total pressure 24 bar, molar ratio H2/C4 0.2 and temperature 150°C. Along with kinetic investigations, the contribution of mono- and bimolecular mechanisms in isobutane formation, as well as the impact of parameters on the changes in isomerization mechanism were analyzed. On the background of experimental kinetic studies on Pd-SZ catalyst, a simplified kinetic model of n-butane isomerization was elaborated and a set of kinetic parameters was evaluated by by means of the standard computer procedure.