Sulfur Fischer-Tropsch catalysts

At this point, the system was tested with catalyst for activation and FTS, in the hopes that the seal leak rates would be impeded by the presence of small catalyst particles. The FTFE 20-B catalyst (L-3950) (Fe, 50.2% Cu, 4.2% K, 1.5% and Si, 2.4%) was utilized. This is part of the batch used for LaPorte FTS run II.20 The catalyst was activated at 543 K with CO at a space velocity (SV) of 9 sl/h/g catalyst for 48 h. A total of 1,100 g of catalyst was taken and 7.9 L of C30 oil was used as the start-up solvent. At the end of the activation period, an attempt was made for Fischer-Tropsch synthesis at 503 K, 175 psig, syngas SV = 9 sl/h/g catalyst, and H2/CO = 0.7. However, the catalyst was found to be completely inactive for Fischer-Tropsch synthesis. Potential reasons for catalyst poisoning under present experimental conditions were investigated. Sulfur and fluorine are known to poison iron-based Fischer-Tropsch catalysts.21,22 Since the stator of the pump is... 

It is well known that all sulfur compounds rapidly deactivate iron, cobalt and nickel Fischer-Tropsch catalysts. However, due to the efficiency of modem gas purification processes such as (he Lurgi Kectisol process, the sulfur level in synthesis gas can be reduced below 0.03 tng/mj. Tiiis level is tolerable and a constant synthesis gas conversion can be achieved [15], Iron catalysis which have been poisoned by sulfur are not readily reactivated. Only very thorouglt reoxidation by which all traces of sulfur are burnt away efficienily. followed by reduction, is effective [15,21J. 

Fischer-Tropsch catalysts are sensitive to poisoning by sulfur-containing compounds. The sensitivity of the catalyst to sulfnr is greater for cobalt-based catalysts than for their iron connterparts. 

Fischer Tropsch technology is best exemplified by the SASOL projects in South Africa. After coal is gasified to a synthesis gas mixture, it is purified in a rectisol unit. The purified gas mixture is reacted in a synthol unit over an iron-based catalyst. The main products are gasoline, diesel fuel, and jet fuels. By-products are ethylene, propylene, alpha olefins, sulfur, phenol, and ammonia which are used for the production of downstream chemicals. 

A similar chain-growth mechanism was said to occur with the first molybdenum-sulfur-potassium based catalysts of table I (15). For such a chain-growth mechanism, the heavier the average molecular weight of alcohols, the greater the formation of heavy compounds and, more often than not, the lower the alcohols selectivity. Furthermore, in Fischer-Tropsch type catalysts (24,25) diffusion limitations, mostly due to the presence of liquid products condensed in the micro porosity, increase with the size of diffusing molecules. These molecules are capable of... 

The purification step in the route 1 approach removes all of the H2S and COS in the raw product gas from the gasifier in addition to the carbon dioxide. Sulfur acts as a catalyst poison to Fischer-Tropsch, methanation and methanol catalyst systems, so pure sulfur-free gases must be used in these synthesis reactions. 

Sulfur poisoning is a key problem in hydrocarbon synthesis from coal-derived synthesis gas. The most important hydrocarbon synthesis reactions include methanation, Fischer-Tropsch synthesis, and methanol synthesis, which occur typically on nickel, iron, or cobalt, and ZnO-Cu catalysts, respectively. Madon and Shaw (2) reviewed much of the early work dealing with effects of sulfur in Fischer-Tropsch synthesis. Only the most important conclusions of their review will be summarized here. 

Although metals or even promoted metals have very low sulfur tolerances in synthesis reactions, other materials, such as metal oxides, nitrides, borides, and sulfides, may have greater tolerance to sulfur poisoning because of their potential ability to resist sulfidation (18). The extremely low steady-state activities of Co, Ni, and Ru metals in a sulfur-contaminated stream actually correspond to the activities of the sulfided metal surfaces. However, if more active sulfides could be found, their activity/selectivity properties would be presumably quite stable in a reducing, H2S-containing environment. This is, in fact, the basis for the recent development of sulfur active synthesis catalysts (211-215), which are reported to maintain stable activity/ selectivity properties in methanation and Fischer-Tropsch synthesis at H2S levels of 1% or greater. Happel and Hnatow (214), for example, reported in a recent patent that rare-earth and actinide-metal-promoted molybdenum oxide catalysts are reasonably active for methanation in the presence of 1-3% H2S. None of these patents, however, have reported intrinsic activities... 

The Fischer-Tropsch (FT) synthesis leads to a broad range of products, i.e. hydrocarbons, alcohols, acids, esters, etc. The increasingly stringent regulations on the sulfur and aromatics content in fuels are the reasons for renewed interest in this reaction [1]. More efficient catalysts are required to improve FT activity and selectivity to the desired products. Cobalt catalysts have been found to be most suitable for the production of higher hydrocarbons [2]. Optimization of the metal function (Co, Fe, Ru, Mo) in supported FT catalysts has been studied in a large number of papers [3-6]. 

One of the ways in which natural gas could be converted to liquid products is by Fischer-Tropsch synthesis. In this process, methane is reformed with steam and oxygen to produce a synthesis gas that is a mixture of carbon monoxide and hydrogen. The synthesis gas is then reacted over a catalyst to produce a variety of fuels. However, recently the most emphasis has been on the production of high-cetane, sulfur-free diesel fuel. Fischer-Tropsch fuels can be produced at the equivalent of 14 to 20 a barrel of oil, and plants with capacities of 10 to 100,000 barrels a day have either been built or designed.1... 

Description The SUPERFLEX process is a proprietary technology patented by ARCO Chemical Technology, Inc. (now LyondellBasell) and exclusively offered worldwide for license by KBR. It uses a fluidized catalytic reactor system with a proprietary catalyst to convert low-value feedstocks to predominantly propylene and ethylene products. The catalyst is very robust thus, no feed pretreatment is required for typical contaminants such as sulfur, water, oxygenates or nitrogen. Attractive feedstocks include C4 and C5 olefin-rich streams from ethylene plants, FCC naphthas or C4S, thermally cracked naphthas from visbreakers or cokers, BTX or MTBE raffinates, olefin-rich streams removed from motor gasolines, and Fischer-Tropsch light liquids. 

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