Temperature-Programmed and X-Ray Diffractometry Studies of WO₃ Reduction by Carbon Monoxide

Abstract

Tungsten (VI) oxide (WO3) reduction by carbon monoxide were examined using temperature-programmed reduction (TPR) and X-ray powder diffractometry (XRD) studies. Results show that WO3 start to reduce at 20% (CO in N2) at temperature 900 °C and the intermediate phases WO2.9 and WO2.83 were observed. The WO3 was reduced and transformed the completely to the WO2.72. As comparison, reduction by using 10% (H2 in N2), WO3 was reduced completely toWO2. The WO3 is a stable oxide because the reduction agent used to promote the reduction was not sufficient enough to reduce to zero metal tungsten.

Establishing patterns of the structural-phase transformations during the reduction of tungsten-containing ore concentrate with carbon

“…The phase composition of the reduction products at the O:C ratio in the charge of 2.30 indicates the transition of the highest tungsten oxides to WO 2 along with the formation of W. This is consistent with the results reported in works [4][5][6], which describe the stages in the reduction process with the formation of tungsten oxides as intermediate components of the reactions. At the O:C ratios in the charge of 1.65 and 1.33, along with the reduction to W, there are the reactions of W 2 C formation.…”

“…The formation of intermediate oxides such as WO x during the reduction in the WO 3 -C system was established by the authors of paper [5]. Intermediate oxides WO 2.9 , WO 2.83 , and WO 2.72 were detected during the WO 3 carbon thermal treatment in work [6]. The progress of reduction in several stages with the formation of WO 2.72 and WO 2 and subsequent post-reduction is noted in work [4].…”

“…Study [5] provides data on that the WO 3 -C system mainly produces compounds of the WO x type at temperatures below 880 °C. At temperatures above 960 °C, the products of the reduction reactions were WO 2 and W. It was shown in [6] that at a temperature of 900 °C, with a content of 20 % by volume CO (in an N 2 atmosphere), WO 3 begins to be reduced with the formation of intermediate oxides WO 2.9 and WO 2.83 . WO 3 was then fully reduced to WO 2.72 .…”

Effect of Zirconia and Nickel Doping on the Reduction Behavior of Tungsten Oxide in Carbon Monoxide Atmosphere

“…However, addition of Zr to WO 3 enhanced the reducibility by lowering the reduction temperature. It can be concluded that, increasing the reaction time in the reduction process could improve the reducibility of the WO 3 [15]. Different holding time will produce different reduction products due to different interaction with reducing agents towards changes in reduction phases.…”

Ag-Doped WO3 Nanoplates as Heterogenous Multifunctional Catalyst for Glycerol Acetylation, Electrocatalytic and Enhanced Photocatalytic Hydrogen Production

“…Interesting nanosize domain for particles have attained appreciable recognition for their fundamental scientific interest besides diverse technological applications involving catalysis because of easily accessible large number of active sites and high specific surface area. , Effectual structural controlled synthesis of metal-oxide nanoparticles and heterostructures is gaining considerable interest for the tuning of particles at the nanoscale which exhibit incomparable physical and chemical properties with their latent utilization in various fields such as catalysis, hydrogen production, gas-sensing, energy storage, and so on. , Transition metal oxides can display properties covering all characteristics of solid state and material science which make them the most versatile class with larger family of materials . Tungsten oxide attained a lot of interest in research due to its remarkable properties for widespread applications as it forms various compounds since the tungsten metal has several oxidation numbers . Tungsten oxide (WO 3 ) has a wide band gap in the range of 2.6–3.0 eV, and it is an n-type semiconductor material .…”