Highly active and stable n-pentane isomerization catalysts without noble metal containing: Al- or Ga-promoted tungstated zirconia

This paper reports on the isomerization of n-pentane over Al- or Ga-promoted tungstated zirconia (WZ) in the presence of hydrogen. The catalytic activity was significantly improved with the addition of Al or Ga to WZ (AWZ or GWZ). It was found that both AWZ and GWZ catalysts have higher activities for the isomerization of n-pentane: conversion is over 70% and the selectivity to iso-pentane reaches ~ 92% at 215 °C. These catalysts exhibit excellent stability and the deactivation is undetected for 1000 h operation. The promoted-WZ catalyst is a mixed oxide solid acid catalyst without noble metal. Furthermore, the alkanes isomerization catalyst is halogen-free, which is environmentally friendly. The promoted-WZ was characterized by Fourier-transformed infrared spectroscopy (FT-IR), NH₃ adsorption microcalorimetry and X-ray photoelectron spectroscopy (XPS). The remarkable activity and selectivity for n-pentane isomerization are due to enhanced strong acid sites and redox properties in the promoted-WZ.