Preparation and Adsorption Properties for Thiophene of Nanostructured W₂C on Ultrahigh-Surface-Area Carbon Materials

Nanostructured tungsten carbides on ultrahigh-surface-area carbon (>3000 m 2 /g), a kind of novel carbon material with uniform pore distribution, have been prepared by carbothermal reduction, carbothermal hydrogen reduction, and metal-promoted carbothermal hydrogen reduction under mild conditions. The resulting carbides have been characterized by X-ray diffraction, transmission electron microscopy, temperature-programmed reduction−mass spectroscopy, and N 2 physico-sorption. The adsorption properties of thiophene on nanostructured tungsten carbides on ultrahigh-surface-area carbon were also investigated in a fixed-bed reactor. The results show that nanostructured W 2 C particles of about 10 nm on ultrahigh-surface-area carbon material can be synthesized by carbothermal reduction and carbothermal hydrogen reduction at 850 °C. Nanostructured W 2 C has also been obtained by metal Ni-promoted carbothermal hydrogen reduction even at 650 °C. The results also show that carbothermal hydrogen reduction can form tungsten carbides under relatively mild conditions compared to carbothermal reduction, and addition of Ni further decreases formation temperatures of tungsten carbides. Tungsten carbides formation involves the sequence WO 3 → WO x (0 < x < 3) → W → W 2 C → WC. The results on adsorption show that W 2 C/HSAC has superior properties for removal of sulfur-containing compounds in fuel oil and the adsorption properties can be recovered after H 2 reduction at 800 °C. The adsorption capacity of the samples on thiophene is in the following order: W 2 C/HSAC > W/HSAC > WC/HSAC ≫ HSAC. Nanostructured W 2 C/HSAC may be of great potential in ultra-deep removal of sulfur-containing compounds in fuel oil.