Significant catalytic recovery of spent industrial DuPont catalysts by surface deposition of an amorphous vanadium-phosphorus oxide phase

Blanco, Raquel; Shekari, Ali; Carrazán, Silvia González; Bordes‐Richard, Elisabeth; Patience, Gregory S.; Ruíz, Patricio

doi:10.1016/j.cattod.2012.04.019

Cited by 9 publications

(14 citation statements)

References 24 publications

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“…In the past few decades, many studies have been conducted to investigate the deactivation mechanism of vanadium phosphorus (VPO) catalysts and prevent catalyst deactivation using metal promoters [30] . The deactivation mechanisms of the VPO catalyst can be a) amorphous phases crystallization b) the surface accumulation of carbonaceous species c) over-reduction or over-oxidation of vanadium d) loss of phosphorus e) agglomeration or sintering in a long duration oxidation [30] .…”

Section: Vpo Surface Chemistry Deposition Of An Amorphous V-p-o Phasementioning

confidence: 99%

“…Both optimum combination of V 4+ and V 5+ and P/V ratio moderately higher than 1.0, increase the activity and selectivity of the catalyst and the higher P/V ratio results in a lower catalyst over oxidation (V 4+ into V 5+ ) [30] . Moreover, the VPP catalyst can be deactivated by crystalline VPO 4 phases formation due to both extreme oxidation and high temperature caused by hot spot in reactors [30] . The VPO active sites as a thin amorphous layer exist on the top surface of (VO) 2 P 2 O 7 [30] .…”

Section: Vpo Surface Chemistry Deposition Of An Amorphous V-p-o Phasementioning

confidence: 99%

“…Moreover, the VPP catalyst can be deactivated by crystalline VPO 4 phases formation due to both extreme oxidation and high temperature caused by hot spot in reactors [30] . The VPO active sites as a thin amorphous layer exist on the top surface of (VO) 2 P 2 O 7 [30] . This active site consists of dispersed V 5+ on the surface of VPP or VOPO 4 microdomains which is coexisting with VPP phase [30] .…”

Section: Vpo Surface Chemistry Deposition Of An Amorphous V-p-o Phasementioning

confidence: 99%

“…The VPO active sites as a thin amorphous layer exist on the top surface of (VO) 2 P 2 O 7 [30] . This active site consists of dispersed V 5+ on the surface of VPP or VOPO 4 microdomains which is coexisting with VPP phase [30] . Both the V 5+ and V 4+ oxidation states present high catalytic performance ;V 5+ sites plays an important role in oxidizing the intermediates to form MA, while V 4+ activates the n-butane [30] .…”

Section: Vpo Surface Chemistry Deposition Of An Amorphous V-p-o Phasementioning

confidence: 99%

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Morphological changes of vanadyl pyrophosphate due to thermal excursions

et al. 2023

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Section: Vpo Surface Chemistry Deposition Of An Amorphous V-p-o Phasementioning

confidence: 99%

Section: Vpo Surface Chemistry Deposition Of An Amorphous V-p-o Phasementioning

confidence: 99%

Section: Vpo Surface Chemistry Deposition Of An Amorphous V-p-o Phasementioning

confidence: 99%

Section: Vpo Surface Chemistry Deposition Of An Amorphous V-p-o Phasementioning

confidence: 99%

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Morphological changes of vanadyl pyrophosphate due to thermal excursions

et al. 2023

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“…Many years later, in 2013, experimental studies demonstrated that the catalyst was reactivated by introducing a small amount of a VPO phase (theoretical P/V atomic ratio = 0.86) on its surface, which allowed n ‐butane conversion and MA selectivity to increase by about 50 % and 15 %, respectively. The deactivation of DuPont's VPO industrial catalysts was actually assigned to the transformation (crystallization) of the amorphous V 5+ ‐containing phases upon long reaction periods . The experimental strategy leading to this finding involved the following aspects: (i) the dynamics of the catalytic process; (ii) the multiphase surface composition and structure of the catalysts; (iii) the nature and oxidation state of active sites; (iv) the catalytic synergy between phases of different composition.…”

Section: Introductionmentioning

confidence: 99%

New concepts in low‐temperature catalytic hydrogenation and their implications for process intensification

et al. 2016

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The study of dynamic catalytic processes occurring at nanoscale provides necessary information to innovate in process intensification (PI). The present study addresses the catalytic performance of Rh, Cu, and Ru-supported nanoparticles, under mild reaction conditions (< 250 8C, < 500 kPa), for three reactions: (i) the hydrogenation of CO 2 to methane, (ii) the hydrogenation of CO 2 to methanol, and (iii) the hydrogenation of N 2 to ammonia. In all systems, the activity and selectivity are promoted by the presence of large metal nanoparticles, and therefore, a broad distribution of sizes is needed for high activity. The enhanced performance of Rh and Ru nanocatalysts results from catalytic cooperation between small and larger metal nanoparticles. Larger particles provide small ones with the hydrogen needed for an efficient hydrogenation of adsorbed reaction intermediates. Large Cu particles promote methanol formation on Cu/ZnO catalysts, indicating that a similar catalytic cooperation might proceed between large Cu particles and the sites adsorbing reaction intermediates. Some particular crystal planes and defects developed in larger nanoparticles would facilitate the activation and transfer of hydrogen, giving rise to a cooperation mechanism via hydrogen supply. More accurate kinetic models can be developed from a deep understanding of dynamic processes occurring at nanoscale. The new models can be later applied in the design and development of high-performance units and plants. In addition, a multidisciplinary PI approach including the study of nanoscale catalytic processes would certainly lead to important improvements on the existing process technologies.

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