Catalysts catalytic coal gasification

CCG [Catalytic Coal Gasification] A generic name. All such processes require very cheap catalysts. Exxon Engineering Corporation developed such a process in the 1980s, which used a catalyst based on potassium carbonate. Tohoku University, Japan developed another process using iron salts deposited on coal. 

Alkalies and alkaline earths serve as effective catalysts in coal gasification processes [ ]. In low rank coals, calcium bound to oxygen anions in carboxyl groups is molecularly dispersed throughout the macerals [2,3]. Similarly, in K-enriched cokes treated at high temperatures, a more or less uniformly dispersed K-C phase is observed [2, ] Such uniform dispersions greatly increase the activity of the catalytic species. 

Hydrocarbons from Synthesis Gas and Methanol. Two very important catalytic processes in which hydrocarbons are formed from synthesis gas are the Sasol Eischer-Tropsch process, in which carbon monoxide and hydrogen obtained from coal gasification are converted to gasoline and other products over an iron catalyst, and the Mobil MTG process, which converts methanol to gasoline range hydrocarbons using ZSM-5-type 2eohte catalysts. 

H-Coal A coal gasification process. Crushed coal is mixed with process-derived oil and catalytically hydrogenated in an ebullated bed under pressure at 455°C. The catalyst is a mixture of cobalt and molybdenum oxides on alumina. Developed by Hydrocarbon Research from the 1960s and piloted in Catlettsburg, KY, from 1980 to 1982. See also CSF, H-Oil, CSF, Synthoil. 

To circumvent such problems, up to two-thirds of the acid gas has been removed from the flame and sent directly to the catalytic reactor, the so-called "long bypass" scheme. This strategy has worked with mixed success in natural gas plants, where hydrocarbons in the acid gas are C1-C3 paraffins, chiefly methane, and no olefins. Such a configuration has been put forward for use in coal gasification plants. In the writer s opinion it is unworkable if the bypassed acid gas contains even traces of olefins or aromatics these compounds react with SO2 to form tarry products which foul the catalyst and discolor the product sulfur. 

This explanation concerning the role of oxide catalysts in the gasification does not hold for temperatures below the Tammann temperature. In the kinetic studies of gasification of coal without an activator, it is frequently assumed that the reaction is not catalytic but is induced by direct gas-solid... 

The work on catalysis reviewed thus far does not include either gasification at elevated pressures or the use of volatile coals. The bench-scale work now reported compares the catalytic activity of various additives in the gasification of volatile coals with steam under pressure and studies other process parameters of interest such as gasification temperature, type of contact with the catalyst, degree of gasification, and repeated use of catalyst. Results of pilot plant gasification tests using additives are also reported. 

Gas-solid reactions between a fluid and a solid are important in a number of applications such as coal gasification, metallic ore processing, and catalyst regeneration. They are related in many aspects to the gas-solid catalytic reactions we have treated in developing the concepts of catalytic effectiveness, but differ in the very important aspect that the solid itself (in the form of a porous matrix) is one of the reactants. Since the solid phase itself is involved in reaction, often conditions of diffusion/ reaction change with time of reaction and the overall process is an unsteady-state one. As with effectiveness factors, many variants on a theme can be envisioned, i.e., is the reaction fast or slow, does the particle porosity (hence D ff) change with reaction, are boundary layer transport effects of importance, etc. We will present in some detail the developments of Wen concerning these questions [C.Y. Wen, Ind. Eng. Chem., 60, 34 (1968) H. Ishida and C.Y. Wen, Amer. Inst. Chem. Eng. J., 14, 311 (1968)]. 

Solid Waste - The steam-reforming process contains up to 8-9 catalytic steps catalysts are replaced after 2-6 years of service. Partial oxidation and coal gasification use 3-4 catalysts. The catalysts contain " hexavalent chromium, nickel, zinc, iron, and mineral supports therefore these materials could not be disposed into landfills, Companies that specialize in producing catalysts or metal-processing companies customarily recycle catalysts. 

Heterogeneous catalysts are used to convert solid coal into gasoline and other chemicals. Solid coal is not easily transformed into hydrocarbon chains, so the conversion requires two general steps gasification followed by catalytic hydrocarbon-forming reactions. Coal is first gasified by reaction with steam ... 

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