Effect of alumina phases on hydrocarbon selectivity in Fischer–Tropsch synthesis

Rane, Shreyas; Borg, Øyvind; Yang, Jia; Rytter, Erling; Holmén, Anders

doi:10.1016/j.apcata.2010.08.038

Cited by 95 publications

(66 citation statements)

References 37 publications

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“…Researchers are also exploring preparation methods to disperse and adequately position metal clusters in spatially favorable ways (i.e., as far apart as possible). Some methods include freeze-drying [60], vapor phase impregnation [61], coating the support with carbon [62], using solvents such as ethylene glycol [63], optimizing drying temperature or calcination chemistry with dilute NO/N 2 [64], bypassing calcination altogether [53], or locking metal particles onto the support so that they cannot find one another and undergo agglomeration [65]. Thus, using advanced preparation methods to obtain spatially uniform distribution of cobalt crystallites is critical, since in conventional cobalt/alumina catalysts prepared by impregnation, cobalt clusters can be within close vicinity to one another, or in grapelike clusters, which have been described as "graveyards" for cobalt active sites during reaction testing [66].…”

Section: Modeling Of Site Suppression and Deactivationmentioning

confidence: 99%

Influence of Reduction Promoters on Stability of Cobalt/g-Alumina Fischer-Tropsch Synthesis Catalysts

Jacobs¹,

Ma²,

Davis³

2014

Catalysts

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This focused review article underscores how metal reduction promoters can impact deactivation phenomena associated with cobalt Fischer-Tropsch synthesis catalysts. Promoters can exacerbate sintering if the additional cobalt metal clusters, formed as a result of the promoting effect, are in close proximity at the nanoscale to other cobalt particles on the surface. Recent efforts have shown that when promoters are used to facilitate the reduction of small crystallites with the aim of increasing surface Co 0 site densities (e.g., in research catalysts), ultra-small crystallites (e.g., <2-4.4 nm) formed are more susceptible to oxidation at high conversion relative to larger ones. The choice of promoter is important, as certain metals (e.g., Au) that promote cobalt oxide reduction can separate from cobalt during oxidation-reduction (regeneration) cycles. Finally, some elements have been identified to promote reduction but either poison the surface of Co 0 (e.g., Cu), or produce excessive light gas selectivity (e.g., Cu and Pd, or Au at high loading). Computational studies indicate that certain promoters may inhibit polymeric C formation by hindering C-C coupling.

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Section: Modeling Of Site Suppression and Deactivationmentioning

confidence: 99%

Influence of Reduction Promoters on Stability of Cobalt/g-Alumina Fischer-Tropsch Synthesis Catalysts

Jacobs¹,

Ma²,

Davis³

2014

Catalysts

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“…Issues explored using SSITKA have included among others the study of mechanisms, the presence and implications of site heterogeneity, the role of chemical promoters and the effect of operation conditions on the surface coverage of intermediates. For FTS, the use of SSITKA has resulted in an improved understanding on the effect of catalyst properties (promoters [72][73][74][75][76][77][78][79][80][81][82][83], support [84][85][86][87][88][89][90], particle size etc. [91][92][93][94]) and the reaction conditions [95][96][97][98][99][100][101] on the performance.…”

Section: Approaches Of Kinetic Analysis For Ftsmentioning

confidence: 99%

Recent Progresses in Understanding of Co-Based Fischer–Tropsch Catalysis by Means of Transient Kinetic Studies and Theoretical Analysis

Yang

Chen

et al. 2014

Catal Lett

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During the last years it has been an increasing focus on fundamental studies of the Fischer-Tropsch synthesis (FTS). Steady-state isotopic transient kinetic analysis and first principles investigation have proven to be important methods in studying the reaction mechanism of FTS. The present contribution deals with recent progresses in understanding of the F-T mechanism on Co catalysts based on combined DFT calculations, in situ characterization, steady-state isotopic transient kinetic analysis and microkinetics. A brief outlook into future perspectives of the FTS for converting synthesis gas from different carbon sources to fuels and chemicals is also provided.

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“…Am ore industrial support, alumina, has been used in as tudy by Holmen et al who did not find any effect of the particle size on the site-time yield but found an optimum for the C 5+ + selectivity. [11,12] However,C laeys et al found that both the activity ands electivity depended on the Co particles ize between 2-10 nm. [14] Recently,t hey stressed the particle-size-dependent role of water on the activity,s electivity,a nd stability of alumina-supported Co catalysts.…”

Section: Introductionmentioning

confidence: 99%

“…Numerous studies have been devoted to gain an understanding of the effect of the support and Co structure on the catalytic performance. [2][3][4][5][6][7][8][9][10][11][12][13][14][15] The precise influence of the catalyst variables remains unclear.T he effect of the Co particles ize on the activity and selectivity is still under debate.…”

Section: Introductionmentioning

confidence: 99%

Measurement of the Influence of the Microstructure of Alumina‐Supported Cobalt Catalysts on their Activity and Selectivity in Fischer–Tropsch Synthesis by using Steady‐State and Transient Kinetics

et al. 2017

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Five alumina‐supported Co catalysts with different particle sizes and structures were synthesized. The catalysts showed different activities during long‐term Fischer–Tropsch experiments. Steady‐state isotopic transient kinetic analysis (SSITKA) 12CO/H2→13CO/H2 experiments were performed during these long‐term runs. The number of active sites for CO adsorption and activation was estimated through the summation of all surface intermediates derived from the SSITKA results. Rather than comparing turnover frequencies, a kinetic analysis was performed. A simple kinetic rate equation based on the in situ number of active sites described the steady‐state CO conversion over the five catalysts adequately. Thus the difference in the catalytic performance could not be attributed to a difference in particle size, phase orientation (face‐centered cubic or hexagonal close packed), or Pt‐promotion effect but instead was only because of the number of reduced Co atoms exposed during the reaction. Similarly, the selectivity depended on the CO conversion level and temperature and not on the catalyst structure.

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Effect of alumina phases on hydrocarbon selectivity in Fischer–Tropsch synthesis

Cited by 95 publications

References 37 publications

Influence of Reduction Promoters on Stability of Cobalt/g-Alumina Fischer-Tropsch Synthesis Catalysts

Influence of Reduction Promoters on Stability of Cobalt/g-Alumina Fischer-Tropsch Synthesis Catalysts

Recent Progresses in Understanding of Co-Based Fischer–Tropsch Catalysis by Means of Transient Kinetic Studies and Theoretical Analysis

Measurement of the Influence of the Microstructure of Alumina‐Supported Cobalt Catalysts on their Activity and Selectivity in Fischer–Tropsch Synthesis by using Steady‐State and Transient Kinetics

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