The molecular weight distribution of the products of the Fischer-Tropsch synthesis

Glebov, L. S.; Kliger, G. A.

doi:10.1070/rc1994v063n02abeh000079

Cited by 37 publications

(26 citation statements)

References 69 publications

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“…The value of the ASF parameter˛for each homologous series is basically the same (e.g., Figure 6 in Glebov and Kliger, 1994). This suggests that the chemical potential of CH 2 (the Lagrange multiplier) is basically constant, regardless of the product mix.…”

Section: Thermodynamic Sensitivity Analysis Of ␣mentioning

confidence: 93%

“…The intersection of the two alphas tends to be at a carbon number of 6 (Glebov and Kliger, 1994;Patzlaff et al, 1999). As the number of available isomers Table 1.…”

Section: Thermodynamic Sensitivity Analysis Of ␣mentioning

confidence: 97%

“…The process has been operated commercially both in Germany and South Africa, and the standard catalysts are either iron or cobalt based with current interest in ruthenium (Schultz, 1999). The molecular weight distribution (MWD) has become of more interest in recent years as demonstrated Glebov and Kliger (1994).…”

Section: Introductionmentioning

confidence: 99%

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Notes on the issues of equilibrium in the Fischer–Tropsch synthesis

Norval

2008

Can J Chem Eng

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The product distribution for the Fischer-Tropsch synthesis is normally described using the kinetically derived (Anderson-Schultz-Flory) ASF model. Variations of the kinetic model have been proposed to explain deviations from the ASF distribution. The Fischer-Tropsch system can be equally well described using a pseudo-element (CH 2 , H 2 , O) equilibrium approach. A one-parameter equilibrium model is derived for the product distributions for alkenes, alkanes and alcohols.The Fischer-Tropsch system should be considered as three separate partial equilibria systems: the product homologous series; the water gas shift system, and the redox behaviour of the catalyst with the H 2 /O ratio of the gas. This approach correctly predicts the impacts of changes in a variety of parameters (temperature pressure, feed composition) on the ASF product distribution. In addition, the catalyst phase changes with gas composition and pressure, indicative of an equilibrium response. Equilibrium is of much greater importance to the Fischer-Tropsch system than previously thought, and the decision to use a complex kinetics-based model rather than a simpler equilibrium based model should be taken with care.La distribution de produits dans la synthèse Fischer-Tropsch est normalement décrite par le modèle ASF (Anderson-Schultz-Flory)établi par la cinétique. Des variations du modèle cinétique sont proposées pour expliquer lesécarts par rapportà la distribution de l'ASF. Le système FischerTropsch peutêtre aussi bien décrit par la méthode deséquilibres de pseudo-éléments (CH 2 , H 2 , O). Un modèle d'équilibreà un paramètre est etabli pour la distribution des alcènes, alcanes et alcools. Le système Fischer-Tropsch devraitêtre considéré comme 3 systèmes d'équilibres partiels séparés: la série homologue de produits, le système de conversion eau-gaz et le comportement redox du catalyseur avec le rapport H 2 :O du gaz. Cette approche prédit correctement l'impact des changements sur plusieurs paramètres (température, pression, composition de l'alimentation) sur la distribution de produits de l'ASF. En outre, la phase du catalyseur change avec la composition du gaz et la pression, indiquant une réactioǹ a l'équilibre. L'équilibre est d'une importance beaucoup plus grande pour le modèle Fischer-Tropsch que ce qu'on pensait, et la décision d'utiliser un modèle complexe basé sur la cinétique plutôt que basé sur deséquilibres plus simple devraitêtre soigneusement pesée.

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Section: Thermodynamic Sensitivity Analysis Of ␣mentioning

confidence: 93%

“…The intersection of the two alphas tends to be at a carbon number of 6 (Glebov and Kliger, 1994;Patzlaff et al, 1999). As the number of available isomers Table 1.…”

Section: Thermodynamic Sensitivity Analysis Of ␣mentioning

confidence: 97%

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Notes on the issues of equilibrium in the Fischer–Tropsch synthesis

Norval

2008

Can J Chem Eng

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“…This model obtained experimentally for polymerization reactions was applied also to fit the hydrocarbon MWD produced by the F-T synthesis and it is known as ASF model [34]:…”

Section: Molecular Weight Distribution (Mwd)mentioning

confidence: 99%

“…The molecular weight distribution of straight alcohols is expected to follows a Schulz-Flory (SF) distribution [32][33][34]. Such distribution is usual in polymer chemistry but also was applied for the Fischer-Tropsch synthesis products molecular weight distribution as Anderson-Schulz-Flory (ASF) model suggesting that C-C bonds formation follows an infinitely diminishing geometrical progression pattern.…”

Section: Introductionmentioning

confidence: 98%

Characterization of Modified Fischer–Tropsch Catalysts Promoted with Alkaline Metals for Higher Alcohol Synthesis

et al. 2012

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Two series of Cu/Co/Cr modified FischerTropsch catalyst promoted with Zn or Mn and an alkaline metal (Me: Li, Na, K, Rb, Cs) were prepared by co-precipitation method and tested for high alcohol synthesis (HAS) at one hour on-stream and at two temperatures, 300 and 350°C. The results indicate that the best selectivity toward high alcohols depends on temperature and catalysts composition and is obtained as follows: a) at 300°C over catalysts without Zn and containing K, Na and Rb; b) at 350°C over catalysts without Zn and containing K; c) at 350°C over catalysts containing Zn as well as Li and Cs.

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Increased prevalence of semaphorin 3C, a repellent of sympathetic nerve fibers, in the synovial tissue of patients with rheumatoid arthritis

Miller¹,

Weidler²,

Falk³

et al. 2004

Arthritis & Rheumatism

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ObjectiveThe presence of selective sympathetic nerve repellents, i.e., semaphorins, may be responsible for the observed reduction of sympathetic innervation in the synovial tissue of patients with rheumatoid arthritis (RA). This study was undertaken to investigate the presence of different semaphorins in synovial tissue of patients with RA, patients with osteoarthritis (OA), and control subjects without inflammation.MethodsIn situ hybridizations with digoxigenin‐labeled RNA probes directed against different semaphorins were performed. The presence of semaphorin 3C (S3C) in the synovial tissue of 10 RA, 10 OA, and 5 control subjects was investigated using a polyclonal antiserum directed against S3C.ResultsAll in situ hybridizations revealed the presence of S3C messenger RNA, but no other investigated semaphorin (i.e., against primary afferent sensory nerve fibers), in the synovial tissue of RA and OA patients. Immunohistologic double staining demonstrated that macrophages and fibroblasts were positive for S3C protein. Quantitative analysis of S3C protein staining showed an increased density of S3C‐positive cells in the synovial tissue of RA patients (mean ± SEM 339 ± 65 cells/mm2) in comparison with OA patients (168 ± 27/mm2; P = 0.031 versus RA) and controls (126 ± 26/mm2; P = 0.027 versus RA). Studies of the relationship between sympathetic nerve fiber density and S3C‐positive cell density in the tissue of all patients showed that RA patients generally had lower densities of sympathetic nerve fibers and higher densities of S3C‐positive cells than OA patients and control subjects.ConclusionThese findings suggest that S3C from macrophages and fibroblasts, which is selectively directed against sympathetic nerve fibers, could be one element responsible for reduced sympathetic innervation in RA tissue. The inability of sympathetic nerve fibers to reinnervate synovial tissue could contribute to the chronic nature of RA.

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The molecular weight distribution of the products of the Fischer-Tropsch synthesis

Cited by 37 publications

References 69 publications

Notes on the issues of equilibrium in the Fischer–Tropsch synthesis

Notes on the issues of equilibrium in the Fischer–Tropsch synthesis

Characterization of Modified Fischer–Tropsch Catalysts Promoted with Alkaline Metals for Higher Alcohol Synthesis

Increased prevalence of semaphorin 3C, a repellent of sympathetic nerve fibers, in the synovial tissue of patients with rheumatoid arthritis

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