Development of CaMn0.775Mg0.1Ti0.125O3-δ oxygen carriers produced from different Mn and Ti sources

• Published in: Materials & design 2016-01, Vol.89, p.527-542
• Main Authors: Jing, Dazheng, Jacobs, Marijke, Hallberg, Peter, Lyngfelt, Anders, Mattisson, Tobias
• Format: Article
• Language: English
• Subjects: Attrition; Calcium manganite; Carriers; Chemical-looping combustion (CLC); Chemical-looping with oxygen uncoupling (CLOU); Combined oxide system; Conversion; Manganese; Nickel; Perovskite oxygen carriers; Raw materials; Titanium; Titanium dioxide
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2015.09.117

Perovskite CaMn0.775Mg0.1Ti0.125O3-δ has attracted great interest as an oxygen carrier. To apply this material to a commercial scale chemical-looping unit, one key challenge is to find raw materials which are cheap and available in large quantities for production. Considering the content and price, Mn- and Ti-oxides are likely the raw materials having the major effect. Twelve Mn-oxide sources and four different TiO2 powders were evaluated for production of CaMn0.775Mg0.1Ti0.125O3-δ in this work. Particles with perovskite structure were successfully spray dried. All oxygen carriers showed oxygen uncoupling characteristics and most of them had a high reactivity, i.e. over 90% methane conversion already at 950°C with a bed mass corresponding to 57kg/MW, when examined in a batch fluidized-bed system at 900–1050°C. Furthermore bulk density, crushing strength and resistance against attrition were studied. Although the attrition index varied, materials with good attrition resistance were identified. The rates of reaction were analyzed using two pseudo-first order apparent rate constants. The rates varied in a wide range, and are generally lower than with optimized Ni-based materials, but higher than with ilmenite. Still, the added oxygen uncoupling likely has a large positive effect at high degrees of solid conversion, something not seen with Ni-based materials. [Display omitted] •Mn- and Ti-oxide sources were examined for production of CaMn0.775Mg0.1Ti0.125O3-δ.•Perovskite structure was formed in all samples, regardless of the Mn- or Ti-source.•The properties of the materials varied depending on the sources used.•An optimized material was produced and presented encouraging behavior.