Neutron Diffraction Studies of Nickel-Containing Perovskite Oxide Catalysts Exposed to Autothermal Reforming Environments

• Published in: Chemistry of materials Vol. 21; no. 20; pp. 4830 - 4838
• Main Authors: Mawdsley, Jennifer R, Vaughey, John T, Krause, Theodore R
• Format: Journal Article
• Language: English
• Published: American Chemical Society 27.10.2009
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/cm901095v

Six nickel-containing perovskite oxides (La1−x Sr x )M0.9Ni0.1O3±δ, where x = 0 or 0.2 and M = Cr, Fe, or Mn) were used to catalyze the autothermal reforming of isooctane (C8H18) into a hydrogen-rich gas during short-term tests at 700 °C. To determine the phase stability of the samples in the reducing environment of the reforming reactor, characterization studies of the as-prepared and tested perovskite samples were conducted using powder X-ray diffraction, powder neutron diffraction, transmission electron microscopy, and scanning electron microscopy. We determined that the reducing conditions of the microreactor caused metallic nickel to form in all six compositions. However, the extent of the nickel loss from the perovskite lattices varied: the chromium-containing compositions lost the least nickel, compared to the manganese- and iron-containing compositions, and the strontium-free compositions lost more nickel than their strontium-containing analogs. Five of the six perovskite compositions tested showed no breakdown of the perovskite lattice despite the loss of nickel from the B-sites, producing only the third example of a B-cation-deficient, 3d transition-metal-containing perovskite.