Fischer-Tropsch Synthesis Of Hydrocarbons Research Articles

Catalytic properties of materials derived from iron-containing clays

The catalytic activities of iron-containing fireclays reduced at 1020°C, determined using the Fischer-Tropsch hydrocarbon synthesis reaction in a wax-slurry reactor, are proportional to the intensity of an unusual singlet peak in the Mossbauer spectra of the reduced samples. This singlet peak is attributed to γ-Fe, a metastable high-temperature form which appears to be stabilized by the cubic host lattice resulting from kaolinite decomposition at ca. 980°C. The enhanced activity of γ-Fe is discussed in terms of steric factors related to the structure of this phase. The effects of different thermal pretreatments and additions of alkali promotors on the catalytic activity are also discussed.

Development of Ideas on the Mechanism of Low-Pressure Synthesis of Hydrocarbons From CO and H2

Abstract The mechanism of Fischer-Tropsch synthesis of hydrocarbons by catalytic hydrogenation of carbon monoxide has not as yet been definitively resolved, even though considerable advances have been made. This article outlines the origin and development of the main ideas on the initiation, build-up and termination of the synthesized hydrocarbon chains. The original theory of the synthesis, involving carbidic surface intermediate, and objections against it are discussed. An account is given of its temporary rejection in the 1950s in favour of the theory of oxygenated surface intermediates. The arguments leading to the rehabilitation of the carbide theory in the mid-1970s and the current mechanistic views are presented.

Carbon-carbon bond formation at dinuclear metal centres

The Fischer-Tropsch synthesis of hydrocarbons probably involves an array of carbon-carbon bond-formation processes occurring to unite carbene, carbyne, alkyl, olefin, and related species on a metal surface. In seeking to understand the nature of such processes, model diruthenium complexes have been prepared and the products of their thermolysis and reactions with unsaturated hydrocarbons investigated. The combination at a diruthenium centre of two carbenes, of a carbene and an alkyne, and of a carbyne and an olefin is described, and the possible implications for metal surface processes are emphasized.

An XPS investigation of the interaction of CH 4, C 2H 2, C 2H 4 and C 2H 6 with a barium surface

The generation and pumping of hydrocarbon gases by a barium getter layer in electronic vacuum devices has been investigated by characterizing a barium film in an ultra high vacuum equipment by means of XPS before, during and after exposures to respectively CH 4, C 2H 2, C 2H 4 and C 2H 6. The reaction conditions (temperatures and pretreatment of the surface, background pressure and exposure doses) closely resemble those in electronic vacuum devices. The probability that a barium layer will react with CH 4 and C 2H 6 was below the detection limit. C 2H 2 and C 2H 4 give rise to the formation of barium carbide compounds and with a high reaction probability. In addition, the interaction with C 2H 2 reveals the formation of carbon-containing surface complexes. Investigations by means of XPS on the C Is spectral features show the presence of at least two groups of carbon-containing surface complexes, which behave differently in response to moderate heating and to an exposure to water vapour. In cases where oxygen is present at the surface, oxygen-containing (hydro) carbon adsorbates are present too. XPS observations of the behaviour of these surface complexes show similarities with reaction steps in the mechanisms proposed for the hydrogenation of CO in the Fischer-Tropsch synthesis of hydrocarbons. Low-pressure hydrogenation of these adsorbates containing hydrocarbons and oxygen can led to the formation of hydrocarbon gases in electronic vacuum devices.

Kinetics and mechanism of the fischer tropsch hydrocarbon synthesis on a cobalt on alumina catalyst

The kinetics of the Fischer Tropsch reaction have been studied on a cobalt on alumina catalyst. The kinetics can be explained satisfactorily by a model in which the initiation proceeds via carbon monoxide dissociation and formation of a CH 2-surface intermediate. The formation of this intermediate is the rate determining step. The chain growth is thought to proceed via the addition of the same CH 2 groups to the growing molecule. The model also explains the influence of the hydrogen and carbon monoxide partial pressures on the olefin/paraffin ratio as determined experimentally for the C 3 fraction, and on the methane selectivity. For high ratios of hydrogen to carbon monoxide, the methane selectivity is higher than predicted, while at the same time a corresponding deficit in the ethene yield is noticed. These two facts are tentatively ascribed to an ethene hydrocracking reaction. The experimental data show that the Schulz Flory (S.F.) “constant” α has a tendency to increase from C 3 to C 7. An analysis on the basis of our model shows that the S.F. constant is a complex function of the partial pressures of hydrogen and carbon monoxide.

ChemInform Abstract: NEW EVIDENCE FOR THE MECHANISM OF THE FISCHER‐TROPSCH SYNTHESIS OF HYDROCARBONS

Chemischer InformationsdienstVolume 12, Issue 12 Preparative Organic Chemistry ChemInform Abstract: NEW EVIDENCE FOR THE MECHANISM OF THE FISCHER-TROPSCH SYNTHESIS OF HYDROCARBONS H. H. NIJS, H. H. NIJSSearch for more papers by this authorP. A. JACOBS, P. A. JACOBSSearch for more papers by this author H. H. NIJS, H. H. NIJSSearch for more papers by this authorP. A. JACOBS, P. A. JACOBSSearch for more papers by this author First published: March 24, 1981 https://doi.org/10.1002/chin.198112195AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume12, Issue12March 24, 1981 RelatedInformation

Sorptive and activity behavior of iron minerals for hydrocarbon synthesis

The sorptive behavior of hydrogen and of carbon monoxide and of their mixtures on a low grade iron ore, magnetite, hematite and a commercial synthetic NH 3—iron catalyst was studied in an attempt to describe their catalytic properties for Fischer-Tropsch hydrocarbon synthesis. In comparison to hydrogen and carbon monoxide adsorbed individually, the adsorption of both the gases is enhanced invariably when adsorbed simultaneously from the mixture. Sorption of hydrogen is enhanced by the presorption of carbon monoxide on the catalyst surface while a small amount of presorbed hydrogen hardly enhances the carbon monoxide adsorption. Initial rates of carbon monoxide hydrogenation, which are most representative of clean surfaces, measured over the temperature range 250–360°C, are in the order hematite > magnetite > synthetic-NH 3-iron > iron ore. From the initial rates, the selectivity for methane formation at 250°C for all the four catalysts is about 20 percent.

New evidence for the mechanism of the fischer-tropsch synthesis of hydrocarbons

New mechanistic evidence is advanced for Fischer-Tropsch synthesis on Ru-loaded Y-type zeolites, Ru-on-silica and Co promoted on kieselguhr. The experiments were carried out in real Fischer-Tropsch conditions, i.e., at high growth rates. Experiments were done in pulse reactors and under transient reaction conditions. 13C-labeled carbon monoxide was used and addition of water and olefins to the synthesis gas was studied. From a series of well-chosen experiments it is deduced that carbon monoxide disproportionation initiates the reaction. Surface carbon is hydrogenated to methane and the reverse water-gas shift reaction accounts for water formation. Water reacts with surface carbon and forms hydroxy-species which initiate chain propagation. The mechanism accounts for a particle size effect and explains why polar conditions stimulate chain growth.

ChemInform Abstract: SURFACE COMPOSITION AND CATALYSIS BY ALLOYS: ON THE RELEVANCE OF SURFACE SCIENCE TO CATALYSIS

Abstract It is to be regretted that only few catalysts have been studied from the point of view of “materials science”. Nevertheless, important information can be obtained on the function of catalysts when, for example, the surface composition of multicomponent catalysts is determined using surface science tools. Two examples of such investigations are discussed: PdAg alloys and NiCu alloys. The data on PdAg alloys show that the vibrational spectra of CO and possibly also the catalytic behaviour of the alloys can be explained by the dilution of palladium in silver, i.e. by essentially “geometrical” effects. The data on NiCu alloys show that the Fischer-Tropsch synthesis of hydrocarbons is a reaction that requires ensembles of several active atoms to occur.

Surface composition and catalysis by alloys: on the relevance of surface science to catalysis

It is to be regretted that only few catalysts have been studied from the point of view of “materials science”. Nevertheless, important information can be obtained on the function of catalysts when, for example, the surface composition of multicomponent catalysts is determined using surface science tools. Two examples of such investigations are discussed: PdAg alloys and NiCu alloys. The data on PdAg alloys show that the vibrational spectra of CO and possibly also the catalytic behaviour of the alloys can be explained by the dilution of palladium in silver, i.e. by essentially “geometrical” effects. The data on NiCu alloys show that the Fischer-Tropsch synthesis of hydrocarbons is a reaction that requires ensembles of several active atoms to occur.

Comparison of the Fischer-Tropsch synthesis of hydrocarbons and the Haber synthesis of ammonia

Comparison of the Fischer-Tropsch synthesis of hydrocarbons and the Haber synthesis of ammonia

Adsorption and Hydrogenation of Gases on Transition Metals

Several principles are suggested which determine the location, and to some extent the behaviour, of gas atoms chemisorbed at the surface of a transition metal. With these as basis, and the published experimental evidence, the structure of adsorbed oxygen, hydrogen, ethylene, acetylene, and carbon monoxide are deduced. For a diatomic molecule three kinds of chemisorbed product are distinguished-adsorbed molecule, adsorbed atom, and adsorbed ion. Bond energies, together with solid models of surface and adsorbate, are used to arrive at the probable mechanism of the ethylene hydrogenation on nickel, and of the Fischer-Tropsch hydrocarbon synthesis.

Physico-Chemical Investigations on Catalytic Mechanism. IX. On the Fischer-Tropsch Synthesis of Hydrocarbons with Special Reference to Factors essential to the Particular Catalysts. (Experimental Series II) (5)

Abstract (1) The experimental materials used in this investigation are briefly described along with the preparations of the catalysts. (2) The experimental procedure with reference to our previous paper is presented. (3) The typical results, as related to the catalytic activity and gaseous products, are tabulated and some correlations are offered. (4) The effects of such promoters as U3O8, Cu, and Mn along with those of a carrier, Kieselguhr, upon the catalytic activity are tabulated and discussed; furthermore, possible correlations with the oil formation are presented. (5) The results of the effects of the reaction temperature, as well as of the pretreatment upon the activity, with special emphasis on the oil formations and gaseous products are presented and discussed rather thoroughly, and some possible correlations are given. (6) Finally, the properties of the liquid products for the series of F19-F29 for the type of catalysts, Co+x%U3O8+y%Cu+z%Mn+w% Kieselguhr, such as refractive indices, specific gravities, apparent molecular weights and elementary analysis data are compiled in the table.

Physico-Chemical Investigations on Catalytic Mechanism. VIII. On the Fischer-Tropsch Synthesis of Hydrocarbons with Special Reference to the Durability of Catalyst. (Experimental Series II) (4)

Abstract (1) The durability experiments with the catalysts, Co+15%ThO2+100% Kieselguhr and Co+12%U3O8+2.5%Cu+100% Kieselguhr, are reported and tabulated. (2) Following mainly the gas analysis data, the normalized reaction was discussed with special reference to the initial formation of CH4. (3) Some correlations with the formation of C2H4, in connection with our reaction mechanism already proposed, as well as the predominating tendency of CH4 formation at higher reaction temperature have been given.

Physico-Chemical Investigations on Catalytic Mechanism. II. Note on The Fischer-Tropsch Synthesis of Hydrocarbons with Special Reference to its Reaction Mechanism

Abstract (1) Introductory remarks for the Fischer-Tropsch reaction in connection with various mechanisms so far proposed are presented briefly. (2) Our proposed mechanism is presented and discussed in detail. (3) The role of CH2 in hydrocarbon chemistry in general is stressed especially in connection with the Fischer-Tropsch reaction mechanism. (4) Approximate values of the activation energies for the reactions involved in the synthesis are presented and discussed in correlation with adsorption. (5) The aspect of polymerization process is discussed, and the question of surface migration is correlated with the polymerization reaction. (6) Adsorption and catalytic activity involved in the synthesis are discussed in the light of our desorption experiment. (7) The proposed mechanism is also applied to Fe type catalyst and discussed. (8) Various pretreatment effects on the catalytic activity are discussed in the light of our experimental evidences.

On the Papers of Mr. Hamai: “Note on the Fischer-Tropsch synthesis of Hydrocarbons with Special Reference to the Reaction Mechanism.”

On the Papers of Mr. Hamai: “Note on the Fischer-Tropsch synthesis of Hydrocarbons with Special Reference to the Reaction Mechanism.”

Experiments on the Fischer-Tropsch synthesis of hydrocarbons from carbon monoxide and hydrogen

Experiments on the Fischer-Tropsch synthesis of hydrocarbons from carbon monoxide and hydrogen

The Fischer-Tropsch synthesis of hydrocarbons, and some related reactions

The Fischer-Tropsch synthesis of hydrocarbons, and some related reactions