The Mechanism of Conversion of Saturated Hydrocarbons Catalyzed by Sulfated Metal Oxides: Reaction of Adamantane on Sulfated Zirconia

A New Deactivation Mechanism of Sulfate-Promoted Iron Oxide

“…These researches results [21,22] support the above deactivation mechanism proposed by us. Additionally, Farcasiu et al [21] proposed an oxidizing mechanism of reactions of alkanes on sulfate-promoted zirconia, thinking that the high activity of sulfate-promoted metal oxides in alkane conversion is due to their oneelectron oxidizing ability, leading to ion-radicals and then to surface sulfate esters, which are the active intermediates in the mechanism. These surface sulfate esters either ionize generating carbocations or eliminate forming olefins, both by carbocationic reactions with no requirement of superacidity.…”

“…In all, the deactivation mechanism proposed by us, supported by our IR results and some other authors' researches [21], [22] can interpret well the deactivation process of the catalyst in the esterification.…”

“…Farcasiu et al [21] confirmed the existence of surface sulfate esters appearing on sulfate-promoted zirconia during the conversion of benzene, and Suwannakarn et al [22] also confirmed the existence of surface sulfate esters appearing on sulfate-promoted zirconia during the transesterification of triglycerides. These researches results [21,22] support the above deactivation mechanism proposed by us.…”

“…cations and/or Bronsted acidic sites generated by strong Lewis-acidic Fe 3? cations, and may be subsequently turned into 1-butene and 2-butene (seen in Scheme 1) and other side products [21], which may progressively accelerate the deactivation of the catalyst.…”

“…The broad band at 3,423 cm -1 is the stretching vibrating adsorption band of the O-H bond in the surfaced hydroxyl and in the planar water, and the band at 1,630 cm -1 is due to the d-HOH vibration [16,[19][20][21].…”