For hydrocarbon synthesis

Kravtsov, A.V., Moizes, O.E., Usheva, N.V., and Yablonskii, G.S. 1988. Kinetic model for hydrocarbon synthesis from CO and H2 accounting for its intragroup distribution. React. Kinet. Catal. Lett. 36 201-6. 

Bechara, R., Balloy, D., and Vanhove, D. 2001. Catalytic properties of Co/Al203 system for hydrocarbon synthesis. Appl. Catal. A 207 343-53. 

The CO-hydrogenation reaction, or Fischer-Tropsch (F-T) synthesis reaction, has been thoroughly investigated since its discovery fn the 1920 s [1]. A range of catalysts has been shown to be active for hydrocarbon synthesis and iron [2] and cobalt [3] have found commercial applications in this field. A variety of reactors have been developed to optimize the synthesis reaction [4]. Variations of reactor conditions have been shown to maximize specific products from the broad range of products produced in the reaction [5). 

The work just cited refers to beds of small diameter. Designers and operators of large-scale catalytic fluid beds of Group A powders now appreciate that all of these beds function beyond the Lanneau-Kehoe-Davidson transition (Avidan, 1982 Squires et al., 1985). Most are turbulent beds Sasol reactors and some fluid catalytic cracking regenerators are fast beds. Sasol engineers reported successful development of a turbulent bed for hydrocarbon synthesis (Steynberg et al., 1991). 

The dramatic increase of mineral oil prices has caused intense efforts to develop alternative sources to provide liquid fuels and raw materials for the chemical industry. Due to limited resources, the production of mineral oil is predicted to peak before the year 2000 and to decline from tlien on (Figure 1) [1]. Resources of coal arc estimated to be ten times larger than those of mineral oil. Thus, in the long run, production of coal will exceed that of oil and processes for hydrocarbon synthesis will be based on coal. The economy of these processes is dependent on the oil-to-coal price ratio and the date of their technical realization is difficult to foresee at present. 

Kolbel and coworkers (3) have calculated the formation enthalpies for hydrocarbon synthesis from CO/H2 at mainly on the basis of Equations... 

The effects of compositions and reaction conditions on product distribution were investigated over various metal promoted Cu-based catalysts to improve the performance for synthesis of hydrocarbons. The formation of carbon monoxide was suppressed and the formation of hydrocarbons increased with the increase in the amount of Fe. The synergetic effect between copper and iron was required for hydrocarbon synthesis. 

D. Pretreated iron ores were successfully used for hydrocarbon synthesis at higher temperatures during the American development of the process [see Sec. II.2.e(3)]. 

It is of particular interest that spent ammonia catalysts, containing iron-nitrogen compounds were superior in many ways to fresh "ammonia catalysts for hydrocarbon synthesis. 

Anderson, Schults, Seligman, Hall, and Storch (74) studied the behavior of iron nitrides as catalysts for hydrocarbon synthesis. The e-phase nitrides which have the same crystal structure as the hexagonal Fe2C have a similar favorable influence on catalyst activity. The nitrides are gradually converted to the corresponding carbon compounds. Nitrided catalysts are more resistant to oxidation and the formation of free carbon. These factors may be important for a longer life of these catalysts (75). 

Basic research work. Emmett, Storch, Taylor, and co-workers, and other scientists carried out basic research work which directly or indirectly influenced the development work on catalysts for hydrocarbon synthesis. The studies of Emmett and Brunauer on adsorption of gases by different types of catalysts (75a) and the publications of Taylor and co-workers on activated adsorption (75b) are of particular importance. Emmett also published investigations on the reaction mechanism of hydrocarbon synthesis (Sec. III.4). 

The optimum conditions of pressure and temperature for hydrocarbon synthesis on nickel, cobalt, iron, and ruthenium are close to the conditions at which formation of carbonyls and carbonyl hydrogen compounds can be detected. Pressure requirements for the catalytic synthesis and for carbonyl formation appear to be closely parallel in the case of metallic catalysts. 

Conversion of the bulk of the catalyst metal to carbide during hydrocarbon synthesis is only observed in the case of iron catalysts. The carbide formation, which occurs parallel with the activity of iron catalysts, may have an important influence on the conditions of the catalyst structure and catalyst surface. The carbide formation, however, seems to be insufficient for the catalyst activity. Treatment of carbided iron catalysts with sulfur does not change the carbide content but makes the catalyst inactive for hydrocarbon synthesis (134). 

T,his report summarizes some results of an investigation using a novel type of arc for hydrocarbon synthesis. The principal reacting system was carbon and hydrogen. Substitutions for hydrogen were also employed in a limited way, including a 50-50 vol % mixture of CO and H2, steam, and a solid petroleum residue, essentially (CH2)ar. 

Carbon monoxide hydrogenation, for hydrocarbon synthesis, 1, 116 Catalysis research, electron diffiraction applicable to, 13, 191 Catalysis,... 

Coal gasification plants are in operation today and are used mainly for the production of hydrogen for ammonia synthesis and the production of carbon monoxide for chemical processes and for syngas feed for hydrocarbon synthesis. 

Farley, R. and D. Ray. The Design and Operation of a Pilot Scale Plant for Hydrocarbon Synthesis in the Slurry Phase. J. 

Clean tungsten carbides, a-WC and a-W C, form essentially only hydrocarbons from CO—H2 reactions. At 673 K and atmospheric pressure, the main products on WC, W2C, and W are methane, CO2, and H2O (121). Ethane and propane are also formed at lower temperatures. WC was substantially more active than W2C and W. The nature of the products can be modified by oxide promoters, as for the case of Rh or Pt, or by the carbon vacancies at the surface (122). At 573 K and 5 MPa with 2H2/CO, turnover rates (based on sites titrated by CO chemisorption) of 0.25-0.85 s were reported for hydrocarbon synthesis over bulk and Ti02-supported tungsten carbides. In addition, WC and WC/Ti02 produced alcohols and other oxygenates with 20-50% selectivity. However, W2C of more metallic character did not produce any oxygenates. Coexistence of carbidic and oxidic components on the catalyst surface appeared to be responsible for alcohol formation. 

For the synthesis of higher hydrocarbons by Fischer-Tropsch, cobalt and iron are the most used metals. Under the form of trivalent cations, they have close ionic radii, which allow their crystallization in an ABO3 structure with La in the A sites. The final goal is the formation after reduction (partial or total) of an efficient catalyst for hydrocarbons synthesis. The most simple combination is to synthesize mixed La(Co cFei )03 perovskites. Bedel et al. [36] studied the preparation, by a sol-gel-like method, of these perovskites over the whole range of... 

The reaction is done with a metal catalyst. Catalysts based upon iron or cobalt have been used commercially for hydrocarbon synthesis [5], The mechanism involves adsorption of hydrogen and carbon monoxide on the metal surface [6]. The Fischer-Tropsch process enables natural gas to be converted to liquid synthetic fuel. First, the natural gas is oxidized to syn gas which is then converted by the Fischer-Tropsch process to the liquid hydrocarbon mixture, which is useful as fuel. 

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