Comparison of structural models for gas-solid reactions in porous solids undergoing structural changes

✍ Scribed by Bengt Lindner; Daniel Simonsson

• Publisher: Elsevier Science
• Year: 1981
• Tongue: English
• Weight: 863 KB
• Volume: 36
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(81)85113-5

✦ Synopsis

Ah&act-In many gas-solid reactions the porous solid undergoes structural changes due to differences in molar volume between solid reactants and solid aroducts. In this saner some new models are nroaosed which take into account the effects of structural changes dn the reaction raie.'The models differ in their geometric descriptions of the initial structure of the porous solid but they all take into consideration the decreasing diffusion rate in the growing ash layer and the decreasing gas-solid interfacial area at swelling of the solid struDture during reaction.

The different models are compared with each other and with previously suggested models. A model that regards the initial solid structure as an aggregate of truncated spheres in contact with each other as in the initial stage of sintering seems to be the most realistic and flexible model of those investigated.

This model has been used to predict conversion-time curves for the sulfation of limestone. The predicted curves are in good agreement with experimental results reported in literature. It is also shown that a semi-empirical approach can give essentially the same results with less numerical effort.