Methanol decomposition on electrospun zirconia nanofibers

Abstract

Electrospinning has been used for the preparation of PVP–zirconium acetate nanofibers. The obtained non-woven cloths have been calcined at different temperatures (200–1000°C) and used as heterogeneous catalysts in the gas phase decomposition of methanol. The X-ray diffraction spectra of the zirconia nanofibers show the onset of a semicrystalline tetragonal structure for the fibers calcined at 400°C. Transformation from tetragonal to monoclinic zirconia starts at a calcination temperature between 600 and 800°C. SEM and TEM images of the zirconia nanofibers show fibers with a high aspect ratio and sizes as thin as 200nm. The increase of the calcination temperature results in zirconia fiber catalysts with lower methanol steady state conversions, probably due to changes in the crystalline phase and crystal sintering. The fibers calcined at 500°C yielded the highest methanol conversion and selectivities to dimethyl ether. In general trend, methanol dehydrates to dimethyl ether at the lower reaction temperatures and decomposes to hydrogen and carbon monoxide at the higher reaction temperatures. Deactivation of the catalyst is observed only at the highest reaction temperature, being probably related to deposition over the fiber surface of pyrolytic carbon from cracking reaction of dimethyl ether.