Carbothermal Reduction of Titania in Different Gas Atmospheres

Abstract

The synthesis of titanium oxycarbide by carbothermal reduction of titania was studied in hydrogen, argon, and helium in isothermal and temperature programmed reduction experiments in a tube reactor with continuously flowing gas. In the temperature range of 1000°C to 1500°C, the reduction rate increased with increasing temperature. Formation of titanium oxycarbide started at 1200°C in all three gases. The reduction was the fastest in hydrogen. Formation of titanium oxycarbide in hydrogen was close to completion in 120 minutes at 1300°C, 60 minutes at 1400°C, and less than 30 minutes at 1500°C. The reduction in argon and helium had similar rates and reached 90 to 95 pct after a 300-minute reduction at 1400°C to 1500°C. Faster carbothermal reduction of titania in hydrogen than in argon and helium was attributed to involvement of hydrogen in the reaction. Hydrogen reduced titania to titanium suboxides and reacted with carbon, forming methane, which reduced titanium suboxides to titanium oxycarbide. Titanium oxycarbide synthesized in hydrogen for 180 minutes at 1300°C contained 13 mol pct TiO. At 1500°C, oxygen concentration decreased to a degree corresponding to 1.4 mol pct TiO. In the titanium oxycarbide produced by a 300-minute reduction at 1600°C, the TiO content was 0.6 mol pct.

Synthesis of Ti4O7 Nanoparticles by Carbothermal Reduction Using Microwave Rapid Heating

“…However, the high temperatures and long reaction times required for the reduction of TiO 2 by carbothermal reduction result in the growth and sintering of TiO 2 and submicron-sized Ti 4 O 7 is obtained [13][14][15]. The extent of the reduction is dominated by the holding temperature and time: Ti 4 O 7 is synthesized at about 1000 • C by carbothermal reduction [13][14][15][16]. On the other hand, the grain growth and sintering of TiO 2 nanoparticles occur at a lower temperature, 700 • C [14].…”

Low-temperature Synthesis of Aluminium Carbide

“…[17][18][19][20] The reduction of alumina by CO can be presented by the following reaction: Depositing on the graphite particles, Al2O can be converted to Al vapour (Reaction (6)) and aluminium carbide (Reaction (7)): Equilibrium partial pressures of CO2 (Reaction (2)), Al (Reaction (3)) and Al2O (Reaction (4)) are presented in Fig. 10.…”

Mineral Phase Formation and Zinc Removal during Sintering of Filter Cake Wastes

“…Zinc oxide in filter cake was reduced to zinc vapour (Zn (g)) by Reaction (9). Like carbothermal reduction of other metal oxides, [20][21][22] the above reaction proceeds via the gas phase. CO reacts with ZnO to form Zn vapour and CO 2 , and the latter, further reacts with carbon to regenerate CO (Boudouard reaction (3)).…”