The Physical-Chemical Properties of Chromia-Alumina Catalysts

Surface Chemistry and Spectroscopy of Chromium in Inorganic Oxides

“…Details about the surface chemistry of these materials can be found in the review of Poole and MacIver. 168 Recently, the group of Indovina has studied the activity of Cr/ZrO 2 catalysts in the dehydrogenation of propane. 15 They have shown that mononuclear Cr 3+ species are the active centers, whereas surface oxygens adjacent to this Cr 3+ ion are most probably involved in the dehydrogenation site.…”

Alkane dehydrogenation over supported chromium oxide catalysts

“…The initial Cr-based dehydrogenation catalyst of Frey and Huppke was prepared by coprecipitation of aluminium and chromium nitrates with ammonium hydroxide, but numerous modi®ed preparation procedures have since been developed [6,7]. Many of these preparation methods, mostly differing in their Cr content and type of alkali metal ion, have appeared in the patent literature.…”

“…Since the pioneering work of Frey and Huppke [4,5], the superior properties of supported chromium [6], and by Kearby [7]. Subsequently, numerous papers have been published in the literature on CrO x /SiO 2 , CrO x /Al 2 O 3 and CrO x /ZrO 2 catalysts [8±50].…”

Semi-Conductor Industry

“…Typically, three ESR resonances are reported for chromia/alumina: the γ-, β-, and δ-signal (5,6,22,39). The γ-signal is centered at about g = 1.97, has a width of about 50-60 G, and originates from isolated Cr 5+ species that are stabilized on the surface of alumina in squarepyramidal symmetry (5,6,22).…”