Kinetics of reduction of nickel oxide with CO

✍ Scribed by J. H. Krasuk; J. M. Smith

• Publisher: American Institute of Chemical Engineers
• Year: 1972
• Tongue: English
• Weight: 742 KB
• Volume: 18
• Category: Article
• ISSN: 0001-1541
• DOI: 10.1002/aic.690180308

✦ Synopsis

Initial rates were measured for the reduction of single pellets of nickel oxide with carbon monoxide a t atmospheric pressure and temperatures from 566 to 796°C. The nickel oxide pellets were porous (; l o = 0.032 -0.35) and intrapellet diffusion retarded the rate so thot the shrinking core model was not applicable. Effective diffusivities for the lower porosity pellets were very small, corresponding to tortuosity factors of about 180 for 50 = 0.032 and 92 for GI = 0.062.

The reaction appeared to be first order in carbon monoxide. Rate constants, bosed upon the intraparticle area, indicated an activation energy of 47 kcol/g.-mole over the temperature range 566 to 682°C. A t higher temperatures the rate was constont. These results, while not conclusive, are in agreement with a reaction sequence consisting of formation of nuclei of nickel atoms in the nickel oxide surface, rapid adsorption of carbon monoxide a t the nickelnickel oxide interface, migration of the adsorbed carbon monoxide to the adjacent lattice, and a slow reaction to extract oxygen from the lattice.