Measurements of surface exchange kinetics and chemical diffusion in dense oxygen selective membranes

被引：20

作者：

Bredesen, R

Mertins, F

Norby, T

机构：

[1] SINTEF, N-0314 Oslo, Norway

[2] Univ Oslo, Ctr Mat Sci, N-0349 Oslo, Norway

来源：

CATALYSIS TODAY | 2000年 / 56卷 / 1-3期

关键词：

transient thermogravimetric measurements; chemical diffusion coefficient; surface exchange rare constant; pure and La- and Ti-doped Sr4Fe6O13;

D O I：

10.1016/S0920-5861(99)00289-8

中图分类号：

O69 [应用化学];

学科分类号：

081704 ;

摘要：

The values of the chemical diffusion coefficient (D) and the surface exchange reaction rate constant (k) for the incorporation of oxygen in air, have been determined in Sr4-xLaxFe6-yTiyO13 (+ (x + y)/2) by transient thermogravimetric measurements at 700-1000 degrees C, Only minor changes in the values of D have been observed on doping Sr4Fe6O13 with La and/or Ti. It is suggested that the concentration of interstitial oxygen ions is mainly determined by the inherent properties of the material, and that doping with 10% La and 6.7% Ti on the A- and B-sites do not give significant changes. An activation energy in the range 50-130 kJ mol(-1) was found for D. The values of k were found to be nearly independent of the temperature. k is approximately two orders of magnitude larger than D suggesting that the surface kinetics is only rate limiting in the initial stage of the measurements. (C) 2000 Elsevier Science B.V. All rights reserved.

引用

页码：315 / 324

页数：10

共 11 条

[1]

BALACHANDRAN U, 1997, P 4 WORKSH CAT MEMBR, P15

[2]

BOSE AC, 1998, P 5 INT C IN MEMBR N, P6

[3] IMPORTANCE OF THE SURFACE EXCHANGE KINETICS AS RATE-LIMITING STEP IN OXYGEN PERMEATION THROUGH MIXED-CONDUCTING OXIDES [J].