Untitled

Navalikhina, M. D.; Крылов, О. В.

doi:10.1023/a:1010429804739

Cited by 7 publications

(3 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There are hardly any reports on the direct use of heteropolyacids as hydrogenation catalysts and their role in the process, despite the fact that they are widely used as a component of hydrogenation catalysts. Navalikhina et al [33] proposed a possible hydrogenation mechanism for hydrogenation reactions over a nickel catalyst modified by heteropoly compounds. The mechanism includes the adsorption of hydrogen from the reaction medium on Ni particles, and its migration via a spillover mechanism to the heteropoly material, whereas the reaction substrate is mainly adsorbed on the heteropoly compound.…”

Section: Catalyst Performance In Aldol Reactionmentioning

confidence: 99%

Heterogeneously Catalysed Aldol Reactions in Supercritical Carbon Dioxide as Innovative and Non-Flammable Reaction Medium

Musko

Grunwaldt

2011

Top Catal

View full text Add to dashboard Cite

Aldol reactions of several aldehydes have been investigated over acidic and basic catalysts in supercritical carbon dioxide at 180 bar and 100°C. Both acidic (Amberlyst-15, tungstosilicic acid (TSA) on SiO 2 and MCM-41) and basic (hydrotalcite) materials showed interesting performance in this preliminary study under the entitled reaction conditions. Small and linear aldehydes, such as propanal, butanal, pentanal and hexanal, react more efficiently than the branched 3-methylbutanal, which is converted much slower. Whereas Amberlyst-15 showed the highest conversion based on the catalyst mass, tungstosilicic acid-based catalysts were significantly better if the rates were related to the number of acidic sites ([1000 h -1 ). The rate depends both on the dispersion and the kind of support. Strikingly, tungstosilicic acid (TSA) on MCM-41 was also an effective catalysts for the selective C=C double bond hydrogenation of 2-butenal and is therefore a potential catalyst for the ''one-pot'' synthesis of 2-ethyl-2-hexenal and 2-ethylhexanal via combined hydrogenation and aldol reaction from 2-butenal. A number of characterisation techniques, such as temperatureprogrammed desorption of ammonia (NH 3 -TPD), transmission electron microscopy (TEM), X-ray absorption spectroscopy (XAS), etc. were used to get an insight into the catalyst structure, which support a high dispersion and strong acidity of the tungsten based species on silica and MCM-41.

show abstract

Section: Catalyst Performance In Aldol Reactionmentioning

confidence: 99%

Heterogeneously Catalysed Aldol Reactions in Supercritical Carbon Dioxide as Innovative and Non-Flammable Reaction Medium

Musko

Grunwaldt

2011

Top Catal

View full text Add to dashboard Cite

show abstract

“…14 To overcome this disadvantage, the HPA may be supported on different carriers 8 by using impregnating solution in different solvents, 15 but different results have been published. [16][17][18][19][20][21][22][23][24] The oxidation of alcohols into aldehydes and ketones is a ubiquitous transformation in organic chemistry, and numerous oxidizing agents and noble metals are available to effect this key reaction. [25][26][27] However, the noble metals are not only relatively expensive but also generate copious amounts of heavymetal waste.…”

Section: Introductionmentioning

confidence: 99%

“…In molybdophosphoric acid, thermal decomposition, acidity changes, and loss of the active phase occur, which are due to formation of volatile molybdic acid . To overcome this disadvantage, the HPA may be supported on different carriers 8 by using impregnating solution in different solvents, but different results have been published. − …”

Section: Introductionmentioning

confidence: 99%

Structure and Catalytic Properties of Magnesia-Supported Copper Salts of Molybdovanadophosphoric Acid

et al. 2006

View full text Add to dashboard Cite

The structure and stability of magnesia-supported copper salts of molybdovanadophosphoric acid (Cu(2)PMo(11)VO(40)) were characterized by different techniques. The catalyst was prepared in ethanol by impregnation because this solvent does not hurt texture of the water-sensitive MgO and Cu(2)PMo(11)VO(40). The Keggin-type structure compound may be degraded partially to form oligomerized polyoxometalate when supported on MgO. However, the oligomers can rebuild as the Keggin structure again after thermal treatment in air or during the reaction. Meanwhile, the V atoms migrate out of the Keggin structure to form a lacunary structure, as observed by Fourier transform IR spectroscopy. Moreover, the presence of Cu(2+) as a countercation showed an affirmative influence on the migration of V atoms, and the active sites derived from the lacunary species generated after release of V from the Keggin anion. The electron paramagnetic resonance data imply that V(5+) autoreduces to V(4+) in the fresh catalyst, and during the catalytic reaction a large number of V(4+) ions are produced, which enhance the formation of O(2-) vacancies around the metal atoms. These oxygen vacancies may also improve the reoxidation function of the catalyst. This behavior is correlated to higher catalytic properties of this catalyst. The oxidative dehydrogenation of hexanol to hexanal was studied over this catalyst. After reaction at 553.2 K for 50 h, catalytic properties did not decrease and exhibited higher selectivity (>96.0%) toward hexanal.

show abstract

Application of mixture experimental design for optimization of nickel catalyst promoted with Cu and Mg and supported by kieselguhr for soybean oil hydrogenation

Shaveisi

Sharifnia

2023

Reac Kinet Mech Cat

View full text Add to dashboard Cite

Untitled

Cited by 7 publications

References 6 publications

Heterogeneously Catalysed Aldol Reactions in Supercritical Carbon Dioxide as Innovative and Non-Flammable Reaction Medium

Heterogeneously Catalysed Aldol Reactions in Supercritical Carbon Dioxide as Innovative and Non-Flammable Reaction Medium

Structure and Catalytic Properties of Magnesia-Supported Copper Salts of Molybdovanadophosphoric Acid

Application of mixture experimental design for optimization of nickel catalyst promoted with Cu and Mg and supported by kieselguhr for soybean oil hydrogenation

Contact Info

Product

Resources

About