Catalyst bauxite

The Claus process consists of partial combustion of the hydrogen sulfide-rich gas stream (with one-third the stoichiometric quantity of air) and then reacting the resulting sulfur dioxide and unbumed hydrogen sulfide in the presence of a bauxite catalyst to produce elemental sulfur. Refer to the process flow diagram in Figure 7. 

In the second section, unconverted hydrogen sulfide reacts with the produced sulfur dioxide over a bauxite catalyst in the Claus reactor. Normally more than one reactor is available. In the Super-Claus process (Figure 4-3), three reactors are used. The last reactor contains a selective oxidation catalyst of high efficiency. The reaction is slightly exothermic ... 

Reverse-flow operation for Sulfur Production over Bauxite Catalysts by the Claus Reaction has been considered in Refs 9 and 31. The rate of H2S oxidation by SO2 on bauxite catalysts is very high even at ambient gas inlet temperature, but sulfur condensing at low temperatures blocks the active catalyst surface, and the reaction stops because of catalyst deactivation. In a reverse-flow reactor the periodic evaporation of condensed sulfur from the outlet parts of the catalyst bed occurs. Although it is difficult to remove all the sulfur condensed within the catalyst pellets at the bed edges, after a certain time a balance between the amount of sulfur condensed and evaporated is attained. Using a reverse-flow reactor instead of the two-bed stationary Claus process provides an equal or better degree of... 

Carbonyl sulfide and some of the residual sulfur dioxide are then reacted at 450°C in the presence of a bauxite catalyst to raise the yield of sulfur (Eq. 13.39). 

While natural or activated clay catalysts are no longer employed in the fixed-bed Houdry process, they are still widely used in the fluid process and to a considerable extent in the TCC process. A natural bauxite catalyst is employed in the fixed-bed cycloversion process, developed by the Phillips Petroleum Company. This process is of greater importance as a naphtha reforming process than as a catalytic cracking process. 

C) but did not return to the initial value (Section A) within 40 min. The addition of 15% water vapor (Section D) further decreased the sulfur dioxide removal efficiency. Curve b in Figure 2 depicts the analyses of carbon dioxide when the bauxite catalyst was subjected to the water treatment. The mirror image resemblance of curves b and a in Figure 2 suggests that the reaction stoichiometry is closely represented by Equation 1 and that the poisoning effect of water is essentially caused by its competition for chemisorption on the alumina Lewis acid sites with the sulfur precursor of the intermediate (9) reductant carbonyl sulfide. 

Bauxite catalysts (or alumina) are generally used in the Claus catalytic converters because of their high activity, durability, and low cost. Maximum equilibrium conversions are obtained at the lowest operating temperatures in the Claus catalytic converters. Theoretically, at this reactor temperature ( 230°C), 99% equilibrium conversion is possible. However, because the Claus reaction is a complex equilibrium reaction, the temperature cannot be lowered too much as sulfur will condense on the... 

The presence of COS and CS2 in the Claus tail gas has an adverse effect on the IFP unit sulfur recovery. To minimize the concentration of COS and CS2 in the Claus burner effluent, it is recommended to tun the first Claus converter hotter than normal, and to replace the bauxite catalyst with a more active catalyst. As a general rule, only one tower is required in the IFP unit for a three-stage Claus plant with a sulfur recovery of less than 200 LTPD. 

Different catalysts were used when the Claus process was reintroduced in refineries in 1940-1950. Bauxite, for example, which was already available in refineries to hydrodesulfurize straight-mn naphthas, is a variable mixture of gibbsite and boehmite with iron and silica impurities. When calcined to activate the alumina, it is converted to a catalyst with about 1-12% ferric oxide supported on y-alumina. Bauxite catalysts were successfully used in the Claus process, giving a sulfur conversion greater than 90%. ... 

Nitrile Process. Fatty nitriles are readily prepared via batch, Hquid-phase, or continuous gas-phase processes from fatty acids and ammonia. Nitrile formation is carried out at an elevated temperature (usually >250° C) with catalyst. An ammonia soap which initially forms, readily dehydrates at temperatures above 150°C to form an amide. In the presence of catalyst, zinc (ZnO) for batch and bauxite for continuous processes, and temperatures >250° C, dehydration of the amide occurs to produce nitrile. Removal of water drives the reaction to completion. 

Hydrogen sulfide has been produced in commercial quantities by the direct combination of the elements. The reaction of hydrogen and sulfur vapor proceeds at ca 500°C in the presence of a catalyst, eg, bauxite, an aluminosihcate, or cobalt molybdate. This process yields hydrogen sulfide that is of good purity and is suitable for preparation of sodium sulfide and sodium hydrosulfide (see Sodium compounds). Most hydrogen sulfide used commercially is either a by-product or is obtained from sour natural gas. 

This reaction is cataly2ed by silica, bauxite, and various metal sulfides. The usual catalyst is activated alumina, which also cataly2es the reduction by methane (228). Molybdenum compounds on alumina are especially effective catalysts for the hydrogen sulfide reaction (229). 

Chemical Raw Material. In addition to use as a catalyst raw material, clays are used or have been extensively studied as chemical raw material. For example, kaolin has been investigated as a raw material for aluminum metal production. Kaolin has a 38 to 40% alumina content and is available in the United States in large quantities whereas the higher alumina bauxite reserves are very limited. The Bureau of Mines has actively carried out research in the aluminum from ka olin area for many years. Activity increases whenever imports of bauxite are threatened by war or other trade intermptions (1,22,23). 

Aluminum is produced commercially by the electrolysis of cryolite, Na3AlF6, but bauxite, A1203, is the usual naturally occurring source of the metal. The oxide is a widely used catalyst which has surface sites that function as a Lewis acid. A form of the oxide known as activated alumina has the ability to adsorb gases and effectively remove them. Other uses of the oxide include ceramics, catalysts, polishing compounds, abrasives, and electrical insulators. 

After bauxite treatment the product was fractionated to produce C3-C4 and naphtha (C5-204°C) fractions. The C3-C4 olefin-rich gas was oligomerized over a solid phosphoric acid (SPA) catalyst to produce an unhydrogenated polymer gasoline with a research octane number (RON) of 95 and MON of 82.21 The bauxite-treated FT motor gasoline (RON of 87, MON of 76) was mixed with the polymer gasoline and some natural gas condensates (and crude-oil-derived naphtha) to produce the final motor gasoline product. In this respect it is noteworthy that the Fe-HTFT-derived material was the high-octane-blend stock. 

Cycloversion A petroleum treatment process which combined catalytic reforming with hydrodesulfurization. The catalyst was bauxite. The process differed from the Houdry process in that the catalyst bed temperature was controlled by injecting an inert gas. Developed by the Phillips Petroleum Company and used in the United States in the 1940s. Pet. Refin., 1960, 39(9), 205. 

InTox A process for destroying toxic wastes in aqueous solution by oxidation with oxygen at high temperatures and pressures in a pipe reactor. No catalyst is required. The reactions take place at approximately 300°C and 120 atm. Developed by InTox Corporation, UK, based on a process for extracting aluminum from bauxite developed by Lurgi in the 1960s. See also Zimpro. 

Various catalysts have been used, including activated carbon, bauxite, and bimetallic oxides. The sulfur dioxide is then absorbed in a solution of ammonium sulfite and bisulfite acidula-tion of this yields ammonium sulfate and elemental sulfur. 

Alumina, 2 345t 5 582. See also Activated alumina Aluminum oxide (alumina) Bauxite(s) Calcined alumina Fused alumina Tabular alumina in the activated catalyst layer, 10 41 adsorption capacity vs. years of service, 1 630... 

Spectra of a spent bauxite-based desulfurization catalyst pellet ( 7 x 13 mm, examined in air) are shown in Fig. 9. The outside of the pellet was black and the single-beam spectrum S showed some of the continuum absorption found with chars. The compensated spectrum S/So, however, showed appreciable spectral structure. The broad band near 750 cm is probably due to the bauxite, and the absorptions near 3000, 1320 and 1000 cm-- - to a mixture of hydrocarbons and thio species formed during the reaction. The feature near 1640 cm l is probably caused by an olefinnic species. 

Cracking catalysts include synthetic and natural sihca-alumina, treated bentonite clay, fuller s earth, aluminum hydrosUicates, and bauxite. These catalysts are in the form of beads, pellets, and powder, and are used in a fixed, moving, or fluidized bed. The catalyst is usually heated and hfted into the reactor area by the incoming oil feed which, in mrn, is immediately vaporized upon contact. Vapors from the reactors pass upward through a cyclone separator which removes most of the entrained catalyst. The vapors then enter the fractionator, where the desired products are removed and heavier fractions are recycled to the reactor. 

Although at first sight, the Citrate Process may not appear to be in any way related to the traditional Claus, it is in fact an H2S/SO2 redox reaction in solution with the activating bauxite, carbon, or metal salt type catalyst replaced by a citrate complex with SO2. The chemistry of the process is clearly interesting and of some importance but for the purposes of this review it is sufficient to draw the analogy indicated above. The Citrate Process is yet another reduction process that may require the ancillary generation of H2S from natural gas and product sulphur if the effluent gas stream is solely SO2 as far as sulphur content is concerned. 

The hydrogen sulfide is then oxidized with air at 1000°C over a bauxite or alumina catalyst. The reactions taking place are given below. The Claus process is increasing in popularity and accounted for 24% of sulfur in 1973, 46% in 1980, 74% in 1991, and 87% in 1999. 

Monoethylaniline can also be produced in the vapor phase in a fluidized bed using natural bauxite as the solid catalyst. The elementary reactions are shown in the previous problem. Using an equimolar feed of aniline and ethanol, the fluidized bed produces 3 parts monoethylaniline to 2 parts diethylaniline for a 40% conversion of aniline. Assuming mixed flow of gas in the fluidized bed, find k2lk and the concentration ratio of reactants and products at the exit of the reactor. 

Occurs in nature in abundance the principal forms are bauxites and lat-erites. The mineral corundum is used to produce precious gems, such as ruhy and sapphire. Activated aluminas are used extensively as adsorbents because of their affinity for water and other polar molecules and as catalysts because of their large surface area and appropriate pore sturcture. As adsorbents, they are used for drying gases and liquids and in adsorption chromatography. Catalytic properties may be attributed to the presence of surface active sites (primarily OFT, 02, and AF+ ions). Such catalytic applications include sulfur recovery from H2S (Clauss catalysis) dehydration of alcohols, isomerization of olefins and as a catalyst support in petroleum refining. 

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