The CATOFIN© process produces propylene from propane using a CrO_x /Al₂O₃ catalyst. Despite its use, there are still uncertainties surrounding the nature of Cr species formed during synthesis, regeneration, and aging. It has been observed that ppm levels of Cr₂O₃ can be oxidized to Cr(VI) in air; however, when Cr₂O₃ is in direct contact with Al₂O₃, Cr(VI) formation increased more than 100-fold. To confirm physical contact between Cr₂O₃ and Al₂O₃ results in increased Cr(VI) formation, Cr₂O₃ and Cr₂O₃/Al₂O₃ samples were synthesized, calcined, and characterized. Catalytic activity measurements confirm propylene selectivity inversely tracks with Cr(VI). Wet chemical titration and X-ray absorption spectroscopy (XAS) quantified and determined the structure of the Cr(VI) species. FEFF X-ray absorption near edge structure simulations determined the potential sensitivity of the XAS to the presence of Al³⁺/Cr³⁺ neighboring atoms. XAS correlated to FEFF simulations suggested that Al³⁺_xCr³⁺_2−xCr⁶⁺₃O₁₂ comprises a significant fraction of the Cr(VI) species formed.

CATOFIN© 工艺使用 CrO _x /Al ₂ O ₃催化剂从丙烷生产丙烯。尽管使用了它，但在合成、再生和老化过程中形成的 Cr 物种的性质仍然存在不确定性。已经观察到 ppm 级的 Cr ₂ O ₃在空气中可以被氧化成 Cr(VI)；然而，当 Cr ₂ O _{3与 Al 2} O ₃直接接触时，Cr(VI) 的形成增加了 100 倍以上。为了确认 Cr ₂ O ₃和 Al ₂ O ₃之间的物理接触导致 Cr(VI) 形成增加，Cr ₂合成、煅烧和表征了O ₃和 Cr ₂ O ₃ /Al ₂ O _3样品。催化活性测量证实丙烯选择性与 Cr(VI) 成反比。湿化学滴定和 X 射线吸收光谱 (XAS) 量化并确定了 Cr(VI) 物种的结构。FEFF X 射线吸收近边缘结构模拟确定了 XAS 对 Al ³⁺ /Cr ³⁺相邻原子存在的潜在敏感性。与 FEFF 模拟相关的 XAS 表明 Al ³⁺ _x Cr ³⁺ _2−x Cr ⁶⁺ ₃ O ₁₂包含很大一部分形成的 Cr(VI) 物种。