Mechanistic aspects of the role of chelating agents in enhancing Fischer–Tropsch synthesis activity of Co/SiO2 catalyst: Importance of specific interaction of Co with chelate complex during calcination

Koizumi, Naoto; Ibi, Yukiya; Hongo, Daichi; Hamabe, Yusuke; Suzuki, Shigenobu; Hayasaka, Yasuhiko; Shindo, Takayoshi; Yamada, Masahito

doi:10.1016/j.jcat.2012.02.003

Cited by 22 publications

(14 citation statements)

References 58 publications

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“…161 Further investigation of the 20 wt % Co catalyst with a Co/chelate ratio of 4 showed only one-fourth of the CyDTA was complexed with Co 2+ in the dried material, resulting in the suppressed particle growth of Co 3 O 4 during calcination through stabilization of small cobalt clusters that served as nuclei. 162 Glycols are a popular alternative to improve the dispersion of cobalt catalysts. Borg et al prepared γ-alumina-and α-aluminasupported catalysts with Co loadings of 12, 20, and 30 wt % by impregnation with cobalt nitrate and different ratios of water/ ethylene glycol as the solvent.…”

Section: Activationmentioning

confidence: 99%

Recent Developments in the Synthesis of Supported Catalysts

2015

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Section: Activationmentioning

confidence: 99%

Recent Developments in the Synthesis of Supported Catalysts

2015

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“…However, poor dispersions and inhomogeneous size distributions of cobalt are frequently obtained, which result in the lower mass-specific activity and higher deactivation rate [9,10]. Thus, to achieve higher mass-specific activity of Co-based catalysts, different methods have been explored to increase the cobalt dispersion, such as changing the precursor [9,11], co-impregnation with chelating agents [12][13][14][15][16][17], or modifying the drying or calcination procedure [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

“…Thus, in the impregnation solution, the structures and coordination features of the complexes are diverse [21,22]. Moreover, it has been proved that only a part of Co 2+ in the impregnation solution participated in the complex formation with chelate agents [10,14], which is influenced by the ratio of the chelating agent to metal and the pH of the solution. Thus, varying Co species exist in the impregnation solution, which makes the drying and calcination process less controllable and results in the inhomogeneous Co oxide particles over the support due to the different thermal decomposition behavior and the interaction with the support of the Co species.…”

Section: Introductionmentioning

confidence: 99%

Impact of Coordination Features of Co(II)-Glycine Complex on the Surface Sites of Co/SiO2 for Fischer–Tropsch Synthesis

Hao

Xie

et al. 2020

Catalysts

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To investigate the effect of coordination features of Co(II)-glycine complex on the performance of Co/SiO2 for Fischer–Tropsch (FT) synthesis, Co(II)-glycine complex precursors were prepared by the conventional method, i.e., simply adding glycine to the solution of Co nitrate and novel route, i.e., reaction of glycine with cobalt hydroxide. The SiO2-supported Co catalysts were prepared by using the different Co(II)-glycine complexes. It is found that glycine is an effective chelating agent for improving the dispersion of Co and the mass-specific activity in FT synthesis when the molar ratio of glycine/Co2+ = 3, which is independent to the preparation method in this study. Significantly, the surface Co properties were significantly influenced by the coordination features of the Co2+ and the molar ratio of glycine to Co2+ in the Co(II)-glycine complex. Specifically, the Co(3gly)/SiO2 catalyst prepared by the novel route exhibits smaller and homogenous Co nanoparticles, which result in improved stability compared to Co-3gly/SiO2 prepared by the conventional method. Thus, the newly developed method is more controllable and promising for the synthesis of Co-based catalysts for FT synthesis.

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“…Calcination is required to remove the stabilizing ligands that block catalytic active sites prior to use. It has been reported in the literature that exposure of nanoparticles to elevated temperatures significantly increases nanoparticle size, resulting in decreased total surface area. ,− While chelating agents can be used to diminish or control the size change during calcination, the inevitable size changes remain unpredictable. This unpredictability is not conducive to size-dependent studies or reactions that require fine control over nanoparticle size.…”

Section: Introductionmentioning

confidence: 99%

Switchable Surfactants for the Preparation of Monodisperse, Supported Nanoparticle Catalysts

2017

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Synthesis methods for the preparation of monodisperse, supported nanoparticles remain problematic. Traditional synthesis methods require calcination following nanoparticle deposition to remove bound ligands and expose catalytic active sites. Calcination leads to significant and unpredictable growth of the nanoparticles resulting in polydisperse size populations. This undesired increase in nanoparticle size leads to a decrease in catalytic activity due to a loss of total surface area. In this work, we present the use of silylamines, a class of switchable solvents, for the preparation of monodisperse, supported nanoparticles. Silylamines are switchable molecules that convert between molecular and ionic forms by reaction with CO. Upon addition of an alkane, the switchable solvent behaves as a switchable surfactant (SwiS). The SwiS is used to template nanoparticles to aid in synthesis and subsequently used to release nanoparticles for deposition onto a support material. The use of SwiS allowed for the preservation of nanoparticle diameter throughout the deposition process. Finally, it is demonstrated that supported gold nanoparticle catalysts prepared using SwiS are up to 300% more active in the hydrogenation of 4-nitrophenol than their traditionally prepared analogues.

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Mechanistic aspects of the role of chelating agents in enhancing Fischer–Tropsch synthesis activity of Co/SiO2 catalyst: Importance of specific interaction of Co with chelate complex during calcination

Cited by 22 publications

References 58 publications

Recent Developments in the Synthesis of Supported Catalysts

Recent Developments in the Synthesis of Supported Catalysts

Impact of Coordination Features of Co(II)-Glycine Complex on the Surface Sites of Co/SiO2 for Fischer–Tropsch Synthesis

Switchable Surfactants for the Preparation of Monodisperse, Supported Nanoparticle Catalysts

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