Studies of molybdenum in Mo?Ti oxide catalysts

ESR studies indicate that in Mo–Ti oxide catalysts prepared via the addition of ammonium paramolybdate to pasted titanium hydroxide, Mo⁵⁺ ions are observed in three states: in heteropoly blue, disperse MoO₃ and a solid substitutional solution in TiO₂.

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, , - , - Mo⁵⁺— , MoO₃ TiO₂.

     

Interaction of hydrogen sulfide with molybdophosphoric heteropolyacid

The effect of hydrogen sulfide on P–12Mo heteropolyacid has been studied using ESR, IR spectroscopic and thermal analysis methods. It has been established that hydrogen sulfide can be chemisorbed like water and no entering of sulfur into the anion structure takes place.

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, P–12Mo . , . .

     

ESR identification of formation stages for TiCl3 particles in catalysts for isoprene polymerization

The analysis of ESR spectra from the system TiCl₄+ TIBA in solution under defreezing from 77 to 200 K permitted to identify formation stages of TiCl₃ particles. At first well-ordered Ti ₂ ⁷⁺ structures, and upon subsequent reduction [Ti ₂ ⁶⁺ ]_n are formed. It is the crystallization of the latter that produces TiCl₃ particles.

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TiCl₄+ 77 200 K TiCl₃: Ti ₂ ⁷⁺ , -[Ti ₂ ⁶⁺ ]_n, TiCl₃.

     

ESR studies of the state of molybdenum in silica-molybdenum oxide catalysts

In the synthesis of catalysts on SiO₂ a silica-molybdenum heteropolyacid stable up to 500°C is formed. Its dehydration due to a thermal treatment distorts the octahedral oxygen ligand environment of Mo ions in the heteropolyanion and localizes the unpaired electron captured in reduction.

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SiO₂ , 500°C. .

     

Peculiarities of ESR spectra of V?Ti oxide systems

ESR analysis of 1–20 wt. % V₂O₅ samples heated at 700–950°C has revealed the formation of V⁴⁺ ion clusters upon V⁴⁺ ion stabilization in Ti⁴⁺ substitution points of rutile.     

ESR studies of molybdenum in Ti?Mo heteropoly acid supported on TiO2

ESR studies indicate that in Ti–Mo heteropoly acid supported on TiO₂, two types of Mo⁵⁺ ions are observed, corresponding to stabilization of the heteropoly blue with various degrees of interaction with the surface. , - TiO₂ Mo⁵⁺, .