The interfacial chemistry of the impregnation step involved in the preparation of tungsten(VI) supported titania catalysts

Panagiotou, George D.; Petsi, Theano; Bourikas, Kyriakos; Kordulis, Christos; Lycourghiotis, Alexis

doi:10.1016/j.jcat.2009.01.003

Cited by 50 publications

(55 citation statements)

References 43 publications

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“…The resulting solid was dried overnight at 120°C and then it was calcined in air at 400°C for 3h. Previous works have shown that under these conditions monolayer coverage of the support surface is achieved [26][27][28]. Suitable amount of Co or Ni has been deposited on the surfaces of the calcined solids following the incipient wetness impregnation method in order a synergistic ratio equal to 0.3 to be achieved.…”

Section: Catalyst Preparationmentioning

confidence: 99%

“…A series of aforementioned catalysts supported on TiO 2 was also prepared using the EquilibriumDeposition -Filtration (EDF) method. This technique usually provides catalysts with better surface characteristics and thus better catalytic behavior than conventional impregnation [26][27][28]. Finally, the most active catalysts were evaluated after sulfidation for simultaneous HDO of phenol and HDS of dibenzothiophene.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Hydrodeoxygenation of Phenol Over Hydrotreatment Catalysts in their Reduced and Sulfided States

Platanitis¹,

Panagiotou²,

Bourikas³

et al. 2014

TOCATJ

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Abstract:The influence of the composition of reduced CoMo, NiMo and NiW catalysts on the catalytic performance in hydrodeoxygenation (HDO) of phenol has been investigated. γ-Al 2 O 3 and TiO 2 were used as supports. Different activity orders were obtained over γ-Al 2 O 3 and TiO 2 supported catalysts reflecting the critical role of the support. NiMo catalyst supported on γ-alumina proved to be the most active followed by the CoMo catalyst supported on titania. CoMo and NiMo lab made catalysts were proved to be more active compared to a reduced industrial CoMo catalyst supported on γ-alumina. An increase of phenol conversion in the range 52-230% was obtained at 350°C.A series of CoMo, NiMo and NiW catalysts supported on TiO 2 was also prepared using the "Equilibrium -DepositionFiltration" (EDF) method. The application of this technique, instead of the classical impregnation, increased considerably the activity of the CoMo catalyst supported on titania (48% increase of phenol conversion at 350°C).The most active lab catalysts (wet impregnated NiMo catalyst supported on alumina, EDF CoMo catalyst supported on titania) and the industrial CoMo catalyst were evaluated after sulfidation for simultaneous HDO of phenol and HDS of dibenzothiophene. These catalysts exhibited comparable HDO activities while the first one proved to be superior in HDS. Overall, taking into account the significantly higher loading of the industrial catalyst in the supported elements compared to the lab made catalysts, the latter seems to be quite promising, even in the frame of a co-processing strategy.

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Section: Catalyst Preparationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hydrodeoxygenation of Phenol Over Hydrotreatment Catalysts in their Reduced and Sulfided States

Platanitis¹,

Panagiotou²,

Bourikas³

et al. 2014

TOCATJ

Self Cite

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“…Specifically, we follow the evolution of the various Co(II) species formed at the interface as the surface concentration of the Co(II) increases. The study is part of the entire efforts of our group to rationalize the method of preparation of supported catalysts and shift catalyst preparation from the art to the science [24][25][26][27][28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Structure of Co(II) Species Formed on the Surface of γ-Alumina Upon Interfacial Deposition

Vakros¹,

Bourikas²,

Kordulis³

et al. 2014

TOCATJ

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Abstract:The mode of retention of Co(H 2 O) 6 2+ species at the "γ-alumina/aquatic solution" interface is refined using simulations, adsorption isotherm, potentiometric mass titrations and mainly proton -ion titrations jointly with diffuse reflectance spectroscopy. It was found that the increase in the Co(II) surface concentration affects considerably the kind of the Co(II) species deposited. Mononuclear/mono-substituted inner sphere Co(II) complexes are formed at extremely low Co(II) surface concentration. A mixed surface state involving mononuclear/mono-substituted and binuclear/bi-substituted Co(II) complexes is formed at relatively low Co(II) surface concentration. Only binuclear/bi-substituted Co(II) complexes are formed at intermediate Co(II) surface concentration. Finally, oligo-nuclear inner sphere Co(II) species are formed at relatively high Co(II) surface concentration, in addition to the bi-nuclear ones. The above species concern a range of surface Co(II) concentration extending from zero to 2.7 theoretical surface layers of [Co(H 2 O) 6 ] 2+. The formation of Co(II) surface precipitate starts above these theoretical surface layers. The above indicates that one may control the surface Co(II) concentration, by adjusting the Co(II) concentration in the impregnating solution, and thus the Co(II) surface species formed. This control allows tailoring the preparation of cobalt catalysts supported on γ-alumina and thus the development of effective Co/γ-alumina catalysts.

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“…Only WO 3 /SiO 2 shows the presence of WO 3 as a crystalline phase with an average diameter larger than 50 nm. The large crystallite size obtained in WO 3 /SiO 2 could have been expected [22], since the impregnation solution (at pH & 5) contains negatively charged polytungstate anions [24]. Thus, an electrostatic repulsion is expected between the anions in the impregnation solution and the silica surface (iso-electric point of silica is expected to be between 1 and 2 [25]).…”

Section: Resultsmentioning

confidence: 90%

On the Product Formation in 1-Butene Metathesis over Supported Tungsten Catalysts

2010

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1-Butene metathesis was performed over 8 wt% tungsten catalysts supported on silica, silica-alumina and c-Al 2 O 3 . Under the applied reaction conditions, 1-butene metathesis yields with a relatively large selectivity iso-butene in addition to the expected metathesis products. The isobutene selectivity is high for catalysts with a relative low activity and decreases with increasing metathesis activity. It is deduced that iso-butene formation involves surface tungsten complexes, whose formation inhibits the metathesis activity.

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The interfacial chemistry of the impregnation step involved in the preparation of tungsten(VI) supported titania catalysts

Cited by 50 publications

References 43 publications

Hydrodeoxygenation of Phenol Over Hydrotreatment Catalysts in their Reduced and Sulfided States

Hydrodeoxygenation of Phenol Over Hydrotreatment Catalysts in their Reduced and Sulfided States

Structure of Co(II) Species Formed on the Surface of γ-Alumina Upon Interfacial Deposition

On the Product Formation in 1-Butene Metathesis over Supported Tungsten Catalysts

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