A kinetic study on the structural and functional roles of lanthana in iron-based high temperature water-gas shift catalysts

作者：Hallac Basseem B; Brown Jared C; Baxter Larry L; Argyle Morris D^*

来源：International Journal of Hydrogen Energy, 2014, 39(14): 7306-7317.

DOI：10.1016/j.ijhydene.2014.02.170

• Water-gas shift
• Lanthana
• Iron catalyst
• Spinel
• Kinetics
• Stability

The structural and functional roles of varying amounts of lanthana in co-precipitated high temperature Fe2O3/Cr2O3/CuO water-gas shift catalysts were studied at 1 atm and 350-425 degrees C temperature range. %26lt;br%26gt;Addition of 0.5 wt% of lanthana enhanced the reducibility of the catalyst, increased its surface area and its WGS activity from 24 to 31 mmol CO/(g(cat) min), and reduced the deactivation rate at 400 degrees C from 23% to 11% relative to a similar catalyst with no lanthana. XRD results suggested that 0.5 wt% of lanthana stabilized the iron-chromium cubic spinel structure most efficiently under the operating conditions; however, further additions appeared to disrupt the spinel structure and degrade the performance of the catalysts. %26lt;br%26gt;The power-law and Langmuir-Hinshelwood models provided much better fits to the rate data than either the redox or the Eley-Rideal models, suggesting that the reaction tends to follow an adsorptive mechanism. The CO adsorption equilibrium constant was largest for the catalyst with 0.5 wt% lanthana, indicating that the addition of lanthana might facilitate CO adsorption. Water inhibited the reaction as it strongly adsorbed on the catalyst surface.

• 出版日期2014-5-5