Paraffins Fischer-Tropsch process

Fischer-Tropsch Process. The Hterature on the hydrogenation of carbon monoxide dates back to 1902 when the synthesis of methane from synthesis gas over a nickel catalyst was reported (17). In 1923, F. Fischer and H. Tropsch reported the formation of a mixture of organic compounds they called synthol by reaction of synthesis gas over alkalized iron turnings at 10—15 MPa (99—150 atm) and 400—450°C (18). This mixture contained mostly oxygenated compounds, but also contained a small amount of alkanes and alkenes. Further study of the reaction at 0.7 MPa (6.9 atm) revealed that low pressure favored olefinic and paraffinic hydrocarbons and minimized oxygenates, but at this pressure the reaction rate was very low. Because of their pioneering work on catalytic hydrocarbon synthesis, this class of reactions became known as the Fischer-Tropsch (FT) synthesis. 

Krupp-Kohlechemie A process for making hard paraffin wax from water gas by a variant of the Fischer-Tropsch process. The products were called Ruhrwachse. Developed by Ruhr Chemie and Lurgi Ges. fur Warmetechnie. 

In addition to this, solid acid catalysts can also be used in the hydroisomerization cracking of heavy paraffins, or as co-catalysts in Fischer-Tropsch processes. In the first case, it could also be possible to transform inexpensive refinery cuts with a low octane number (heavy paraffins, n-Cg 20) to fuel-grade gasoline (C4-C7) using bifunctional metal/acid catalysts. In the last case, by combining zeolites with platinum-promoted tungstate modified zirconia, hybrid catalysts provide a promising way to obtain clean synthetic liquid fuels from coal or natural gas. 

The Fischer-Tropsch process, as operated in Germany, produces normal paraffin wax also. These waxes melt in the range of 122° to 243° F. and the molecular size extends up to 150 carbon atoms (60). A United States plant employing iron catalyst does not expect to produce these. 

An important reason for the lack of intermediate molecular weight products has been the unavailability of low cost paraffins with molecular structures suitable for these materials. Synthetic paraffins, prepared by the Fischer-Tropsch process and often known as Kogasin, have been available in this intermediate molecular weight range (10) and have been used in Europe to make chloroparaffins (9). However, these materials also are not completely satisfactory because of a combination of cost, purity, and molecular structure. 

Paraffin, Synthetic, occurs as a white wax that is very hard at room temperature. It is synthesized by the Fischer-Tropsch process from carbon monoxide and hydrogen, which are cata-lytically converted to a mixture of paraffin hydrocarbons the lower-molecular-weight fractions are removed by distillation, and the residue is hydrogenated and further treated by percolation through activated charcoal. It is soluble in hot hydrocarbon solvents. 

In recent years there is an interest in converting natural gas or coal into high quality diesel fuel by the Fischer-Tropsch process (FT). This produces a significant by-product yield of naphtha with high paraffins... 

Hydrogenation of carbon oxides with iron, cobalt, or nickel catalysts (Fischer-Tropsch process). Hydrocarbons are the main products Recovery and separation of oxygenated products obtained from CO and H2 Partial oxidation of nonaromatic hydrocarbon mixtures, e.g., petroleum, paraffins, and natural gas, to produce a mixture of products, such as esters, acids, aldehydes, ketones, and alcohols. This also includes higher fatty acids from petroleum and patents on formaldehyde production... 

The first stage, Heavy Paraffin Synthesis (HPS), converts hydrogen and carbon monoxide into heavy paraffins by the Fischer-Tropsch process. The product distribution is in accordance with Schultz-Flory polymerization kinetics, which is characterized by, the probability of chain growth. 

Since the 1980s, SSITKA has been widely used to understand the formation mechanism of methane as the first paraffin in the chain. The study of the dynamics of the entire complex of reactions involved in the Fischer-Tropsch process became possible only after the development of the GC-MS technique with high resolution time. A review of field suggests that the cycle of papers by van Dijk et al. [18-21] describes the results that were obtained using the full potential of the SSITKA technique. First, a comparison of C, O, and H labeling on different Co-based catalyst formulations and in different conditions was made. For the first time, a substantial part of the product spectrum (both hydrocarbons and alcohols) was included in the isotopic transient analysis. After the qualitative interpretation of the experimental data, extensive mathematical modeling was performed for the identification and discrimination of reaction mechanisms. 

Further CO hydrogenation (Fischer-Tropsch process) gives (-CH2-)n and wata-, but olefins and alcohols are also produced in Iowct amounts than paraffins. 

Engineering aspects of the SMDS process are reviewed here. They include the manufacture of synthesis gas, the production of paraffinic Fischer-Tropsch waxes and the control of the chain length distribution by a selective hydrocracking step. The close interaction between the properties of the individual catalyst particles, the choice of the reactor technology and the overall process performance is discussed in detail. 

A number of chemical products are derived from Sasol s synthetic fuel operations based on the Fischer-Tropsch synthesis including paraffin waxes from the Arge process and several polar and nonpolar hydrocarbon mixtures from the Synthol process. Products suitable for use as hot melt adhesives, PVC lubricants, cormgated cardboard coating emulsions, and poHshes have been developed from Arge waxes. Wax blends containing medium and hard wax fractions are useful for making candles, and over 20,000 t/yr of wax are sold for this appHcation. 

One of the most important, and perhaps the best studied, applications of three-phase fluidization is for the hydrogenation of carbon monoxide by the Fischer-Tropsch (F-T) process in the liquid phase. In this process, synthesis gas of relatively low hydrogen to carbon monoxide ratio (0.6 0.7) is bubbled through a slurry of precipitated catalyst suspended in a heavy oil medium. The F-T synthesis forms saturated and unsaturated hydrocarbon compounds ranging from methane to high-melting paraffin waxes (MW > 20,000) via the following two-step reaction ... 

In this chapter a two a selectivity model is proposed that is based on the premise that the total product distribution from an Fe-low-temperature Fischer-Tropsch (LIFT) process is a combination of two separate product spectrums that are produced on two different surfaces of the catalyst. A carbide surface is proposed for the production of hydrocarbons (including n- and iso-paraffins and internal olefins), and an oxide surface is proposed for the production of light hydrocarbons (including n-paraffins, 1-olefins, and oxygenates) and the water-gas shift (WGS) reaction. This model was tested against a number of Fe-catalyzed FT runs with full selectivity data available and with catalyst age up to 1,000 h. In all cases the experimental observations could be justified in terms of the model proposed. 

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