Operando Raman study of alumina-supported Sb–V–O catalyst during propane ammoxidation to acrylonitrile with on-line activity measurement

Guerrero‐Pérez, M. Olga; Bañares, Miguel Á.

doi:10.1039/b202556f

Cited by 111 publications

(99 citation statements)

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“…Such phase forms during propane ammoxidation. This trend of Sb-V-O/ Al 2 O 3 catalysts to form VSbO 4 during reaction has been followed in detail with catalysts prepared with Sb 2 O 3 by operando Raman-GC spectroscopic study [22,34,35]. Deconvolution of the Raman band near 800 cm )1 has shown that it consists of two Raman bands at 835 and 795 cm )1 [22].…”

Section: Al 2 O 3 Supported Sb-v-o Catalystsmentioning

confidence: 99%

“…This amorphous antimony phase is structurally more reactive than the Sb 2 O 3 Alumina-supported V-Sb-O catalysts prepared with the conventional Sb 2 O 3 suspension exhibit an intense activation during time-on-stream; both, conversion and selectivity increase [29]. This increment in acrylonitrile yield for catalyst 1Sb 1 V/Al prepared with Sb 2 O 3 suspension is due to the progressive formation of VSbO 4 during reaction; which has been determined by the simultaneous determination of structure and activity in an operando Raman-GC study [22,35]. Unlike the catalyst prepared with Sb 2 O 3 suspension, the fresh catalyst 1Sb 1 V/Al prepared with the tartrate method does possess the VSbO 4 phase (figure 4).…”

Section: Alumina-supported Catalystsmentioning

confidence: 99%

“…Sb 2 O 3 is very insoluble, even at pH = 0, which prevents an efficient Sb-V interaction. It would be desirable to promote a redox reaction between V 5+ and Sb 3+ solution towards V 3+ /V 5+ and Sb 5+ as vanadium antimonate, which is the active phase for propane ammoxidation [10,22]. This work studies a new synthesis method in which Sb 3+ is totally dissolved in tartaric acid solution as a soluble complex [28] in order to address this issue.…”

Section: Introductionmentioning

confidence: 99%

“…The use of nano-scaled oxide phases maximizes the surface-to-volume ratio allowing better insight on the nature of the active sites. The nano-scaled phases are stabilized versus sinterization by the use of a support [22,23].…”

Section: Introductionmentioning

confidence: 99%

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Effect of synthesis method on stabilized nano-scaled Sb–V–O catalysts for the ammoxidation of propane to acrylonitrile

2006

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A new synthesis method to prepare V-Sb-O phases on Al 2 O 3 , and Nb 2 O 5 substrates has been investigated and compared with previous works in which a conventional synthesis method was used. The new preparation method leads to an amorphous layer of Sb oxide, which had not been described previously; its Raman bands are reported for the first time. This new method provides an intimate contact between Sb and V during synthesis. It has a clear influence on the structure and catalytic properties of the final catalysts. The total amount (Sb + V), the Sb/V atomic ratio, and the specific support determine acrylonitrile production. Depending on catalyst stoichiometry, different preparation methods are preferred. Standard Sb 2 O 3 suspension method is preferred at Sb/V atomic ratios above 1. The new tartrate method is preferred at Sb/V = 1 atomic ratio, resulting in the best catalytic performance.

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Section: Al 2 O 3 Supported Sb-v-o Catalystsmentioning

confidence: 99%

Section: Alumina-supported Catalystsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of synthesis method on stabilized nano-scaled Sb–V–O catalysts for the ammoxidation of propane to acrylonitrile

2006

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“…However, operando technology requires complete control of both the spectroscopy and catalytic activity to provide data matching the kinetics of the process as originally proposed. 4,5 Thus, cross-disciplinary efforts are highly needed for further advances in this field.…”

Section: Introductionmentioning

confidence: 99%

Does Pelletizing Catalysts Influence the Efficiency Number of Activity Measurements? Spectrochemical Engineering Considerations for an Accurate Operando Study

et al. 2012

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Porosity is a factor affecting catalyst efficiency in pelletized form. This implies that care should be taken with uncritically relating activity measurements from transmission operando FTIR to final catalyst performance. If the pelletizing pressure is excessive, a destruction of the pore structure of, for example, support oxides might take place, which in turn affects the pore size distribution and the porosity of the catalyst, leading to the observation of lower activity values due to decreased catalyst efficiency. This phenomenon can also apply to conventional activity measurements, in the cases that pelletizing and recrushing of samples are performed to obtain adequate particle size fractions for the catalytic bed. A case study of an operando investigation of a V2O5-WO3/TiO2-sepiolite catalyst is used as an example, and simple calculations of the influence of catalyst activity and internal pore diffusion properties are considered in this paper for the evaluation of catalyst performance in, for example, operando reactors. Thus, it is demonstrated that with a pelletizing pressure of <1–2 ton/cm2, the pore structure is only negligibly altered, and small deteriorations of estimated catalyst efficiencies are observed for first-order kinetic constants lower than 100 mL/gs. However, if the operando study deals with highly active catalysts, it is necessary to consider efficiency losses. A simple procedure for evaluating efficiencies based on pellet dimensions and solid phase characteristics is proposed. The Thiele modulus is directly proportional to the thickness of the pellet, and, thus, inversely related to the catalyst efficiency. As a rule of thumb, we found that for catalytic constants below 100 mL/gs, the maximum thickness of the pellet pressed at 2 tons/cm2 has to be as low as 80 μm to exhibit catalyst efficiencies above 90%. For catalysts with k′ = 10 mL/gs, the value is 260 μm. This strongly underlines the importance of taking internal diffusion limitations into account when working with highly active catalysts.

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Raman Spectroscopy of Catalysts

Bañares

Wachs

2010

Encyclopedia of Analytical Chemistry

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This chapter focuses on the application of Raman spectroscopy for characterizing catalytic materials and for the investigation of the bulk and surface chemistry occurring during catalyst preparation and operation; a general theoretical background and description of equipment for Raman experimentation is also presented. Over the past decades, Raman spectroscopy has increasingly been applied for characterization of all types of catalytic materials: bulk and supported metals, bulk mixed metal oxides, supported metal oxides, bulk and supported metal sulfides, zeolites and molecular sieves, heteropolyoxo anions, and clays. Raman is also used to study chemisorption and, in recent years, Raman has been increasingly applied under in situ conditions. There is an increasingly important strong driving force leading research toward the study of catalysts under reaction conditions. The last few years exhibit an increasing number of Raman studies during relevant reaction conditions (operando methodology). This momentum in reaction and operando Raman spectroscopy advances a new revolution in catalysis science that is poised to afford accurate molecular understanding of catalytic structure–activity/selectivity relationships.

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Operando Raman study of alumina-supported Sb–V–O catalyst during propane ammoxidation to acrylonitrile with on-line activity measurement

Abstract: Operando Raman spectra during propane ammoxidation show partially reversible structural transformations of the active phases as a function of reaction environment.

Cited by 111 publications

References 14 publications

Effect of synthesis method on stabilized nano-scaled Sb–V–O catalysts for the ammoxidation of propane to acrylonitrile

Effect of synthesis method on stabilized nano-scaled Sb–V–O catalysts for the ammoxidation of propane to acrylonitrile

Does Pelletizing Catalysts Influence the Efficiency Number of Activity Measurements? Spectrochemical Engineering Considerations for an Accurate Operando Study

Raman Spectroscopy of Catalysts

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