Oxidative dehydrogenation of isobutyric acid with cupric salts of molybdovanadophosphoric acid (CuxH4−2xPVMo11O40). Investigation of catalyst activation and deactivation

Blouet-Crusson, Emilie; Rigole, Monique; Fournier, Michel; Aboukaı̈s, Antoine; Daubrege, Franck; Hecquet, G.; Guelton, M.

doi:10.1016/s0926-860x(98)00275-0

Cited by 26 publications

(17 citation statements)

References 59 publications

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“…A deactivation front moving along the direction of flow was observed previously by Blouet-Crusson et al 15 in the oxidative dehydrogenation of isobutyric acid over HPA catalysts. These authors showed that the deactivation was accompanied by a loss of molybdenum from the catalyst into the gas phase.…”

Section: Industrial and Engineering Chemistry Researchsupporting

confidence: 70%

“…Previous catalyst screening tests showed that the position of the Cu-related reduction peak strongly depends on the structure of the HPA and thereby a change in the elementary composition may explain the shift in the Cu-related peak. The formation of Cu II clusters at the surface described in the literature 15 was not observed.…”

Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 71%

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Processing Study on the Stability of Heteropoly Acid Catalyst in the Oxidation of Methacrolein to Methacrylic Acid

Illies

Kraushaar‐Czarnetzki

2016

Ind. Eng. Chem. Res.

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The oxidation of methacrolein to methacrylic acid over a heteropoly acid catalyst was studied in a pilot scale unit with tubular multisampling reactor. The catalyst performance was monitored at different aging phases during a total runtime of 195 days. Deactivation was accompanied by a loss of catalyst mass through evaporation of molybdenum oxide. With time on stream, deactivation expands from an area close to the inlet of the catalyst bed downstream to the outlet. Several causes for the deactivation were evaluated in processing experiments. Possible detrimental effects of acetic acid and carbon monoxide were excluded by cofeeding these byproducts in high concentrations. A critical parameter is the oxygen concentration because reoxidation of the catalysts is rate limiting. Low oxygen supply results in a depletion of lattice oxygen accompanied by a marked activity loss. It is suggested that continued preservation of the catalyst in the reduced state promotes structural disintegration.

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Section: Industrial and Engineering Chemistry Researchsupporting

confidence: 70%

Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 71%

Processing Study on the Stability of Heteropoly Acid Catalyst in the Oxidation of Methacrolein to Methacrylic Acid

Illies

Kraushaar‐Czarnetzki

2016

Ind. Eng. Chem. Res.

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“…It has been proposed that molybdenum atoms migrate from the heteropolyanion to cationic position [20,24]. Marosi and Otero Areán [39] proposed that a molybdenyl salt [PMo 14 O 42 ] À containing six reduced Mo V can be obtained by calcination of (NH 4 ) 3 [PMo 12 O 40 ] under nitrogen at 740 K. Recently, it has been proposed that a cubic molybdenum autosalified heteropolyanion is formed by thermal treatment of molybdophosphoric acid in 10% propene in helium between 600 and 723 K [40].…”

Section: Catalysismentioning

confidence: 99%

“…and counter-ions [1][2][3][4][5]. For selective oxidation of isobutane [6][7][8][9][10][11][12][13][14], oxidative dehydrogenation of propane [15,16], ethane [17,18] or isobutyric acid [19][20][21] or oxidation of methacrolein [2], heteropolysalts of [PMo 12Àx V x O 40 ] (3+x)À (x = 0, 1 or 2) are efficient catalysts.…”

Section: Introductionmentioning

confidence: 99%

Study of molybdenyl, vanadyl and mixed ammonium vanadyl salts of [PMo12O40]3− as oxidation catalysts

Marchal‐Roch

Julien

Moisan

et al. 2004

Applied Catalysis A: General

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“…Exothermal O 40 , are active and selective catalysts for the oxidative dehydrogenation of isobutyric acid. (23) Both the latter salt and the parent acid have vanadium atoms in octahedral symmetry with a slight distortion inside the Keggin anion. After calcination of the parent acid at 593 K for 1 h, the vanadium ions are believed to be in the 5 oxidation state and approximately 60% are in a tetrahedral environment outside the Keggin anion.…”

Section: Chaptermentioning

confidence: 99%

Stability

2002

Metal-Oxygen Clusters

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A large number of publications have reported studies of the thermal stability of heteropoly oxometalates as part of investigations of other aspects of these materials. Although these reports may have been discussed elsewhere in this monograph where relevant, they have also been included here. The present discussion of thermal stability is, for convenience, restricted to unsupported heteropoly oxometalates with that pertaining to the supported materials included in the section on the properties of the latter. A cautionary note should be added here. The results from studies of stability are dependent not only on the method employed for such evaluations, but in addition are frequently dependent on the conditions under which the experiment was performed.One of the earliest studies of the stability of the heteropoly acids employed differential thermal analysis and X-ray diffraction. (1) With each of the four acids examined, an endotherm and an exotherm are observed at 300 C or less and 340 C or more, respectively (Table 5.1). The low-temperature endotherm is attributed to the removal of water whereas the high-temperature exotherm signals the decomposition of the anion. The authors note that metatungstic acid H 8 [W 12 O 40 ]ÁxH 2 O decomposes at 50 C. When the void in the center of the [W 12 O 40 ] 8À anion is occupied by Si 4 or P 5 , the decomposition temperature increases by approximately 400 or 500 C, respectively. The presence of a positively charged species reduces the effect of thermal vibrations and thus of decomposition.Thermogravimetric analyses of H 3 XW 12 O 40 with X being zinc, iron, cobalt, boron, silicon, or phosphorus, their potassium salts, and their ether-addition compounds have been reported. (2) With the ®rst three acids, three peaks were observed whereas only two were obtained with the latter three acids (Table 5.2). The third peak was attributed to decomposition of the anion. 42CHAPTER 5 STABILITY 43

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Oxidative dehydrogenation of isobutyric acid with cupric salts of molybdovanadophosphoric acid (CuxH4−2xPVMo11O40). Investigation of catalyst activation and deactivation

Cited by 26 publications

References 59 publications

Processing Study on the Stability of Heteropoly Acid Catalyst in the Oxidation of Methacrolein to Methacrylic Acid

Processing Study on the Stability of Heteropoly Acid Catalyst in the Oxidation of Methacrolein to Methacrylic Acid

Study of molybdenyl, vanadyl and mixed ammonium vanadyl salts of [PMo12O40]3− as oxidation catalysts

Stability

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