Abstract
A series of bimetal La- and Ni-promoted S2O82–/ZrO2–Al2O3 (SZA) catalysts were prepared at different calcination temperatures. The effect of calcination temperature on the characteristics and performance of La-Ni-S2O82–/ZrO2–Al2O3 (La-Ni-SZA) catalysts towards the n-pentane isomerisation reaction was determined. In order to relate the catalytic activity to their physical, chemical and textural features, the catalysts were characterised by various techniques including X-ray powder diffraction, thermogravimetric-differential thermal analysis, Fourier transform infrared spectroscopy (FTIR), FTIR spectra of adsorbed pyridine and BET specific surface area and H2 temperature-programmed reduction analyses. The results showed that tetragonal ZrO2 was the dominant phase in the calcination temperature range of 600–700 °C. The change of textural features of the catalysts results from transformation of the ZrO2 crystal phase and the collapse of the partial pore structure occurs at the high calcination temperature of 700 °C. The sulfur could be lost at calcination temperatures > 660 °C. The total acidity of the catalysts at a desorption temperature of 350 °C decreases in the order: La-Ni-SZA-650 > La-Ni-SZA-600 > La-Ni-SZA-700 > La-Ni-SZA-550. The La-Ni-SZA catalyst calcined at 650 °C had more tetragonal phase ZrO2, higher acidity, higher sulfur content, a larger BET surface area and exhibited the best catalytic performance, with the isopentane yield reaching a maximum 66.5% at a lower reaction temperature of 150 °C, with a selectivity to isopentane of 98.5%.