RESOX process

Reduction of sulfur dioxide by methane is the basis of an Allied process for converting by-product sulfur dioxide to sulfur (232). The reaction is carried out in the gas phase over a catalyst. Reduction of sulfur dioxide to sulfur by carbon in the form of coal has been developed as the Resox process (233). The reduction, which is conducted at 550—800°C, appears to be promoted by the simultaneous reaction of the coal with steam. The reduction of sulfur dioxide by carbon monoxide tends to give carbonyl sulfide [463-58-1] rather than sulfur over cobalt molybdate, but special catalysts, eg, lanthanum titanate, have the abiUty to direct the reaction toward producing sulfur (234). 

The SO2 thus formed can then be used to make H2SO4, can be treated with limestone, or can be converted to elemental sulfur. The conversion to elemental sulfur can be achieved either by the Claus process or by treating SO2 with a reductant such as carbon (Trail/Resox process). An attractive way of recovering sulfur is by reacting the SO2 with iron sulfide itself to form iron oxide and elemental sulfur. Thus, if the SO2 formed by the oxidation of iron sulfide is recirculated, elemental sulfur can be produced in a single step. The problem with this scheme is that the elemental sulfur needs to be separated from the exit stream by cooling, and the SO2 needs to be reheated. Karr, et al. ( ) and Schrodt and Best (7) carried out experiments to test the feasibility of this scheme. The latter authors, using coal ash as the sorbent material, concluded that sulfur recovery by this method is both technically and economically unattractive. The same may not be true for the iron oxide-silica sorbent. More studies are necessary before a definite conclusion can be drawn. 

SO2 reduction in heated coal bed, Resox process none S... 

Technically, the regeneration is carried out in a moving bed reactor using sand as a direct heat carrier to heat the adsorbent to 600-650 °C. The effluent gas of the regeneration contains 20-30% sulfur dioxide by volume as well as water and carbon dioxide. It can be fed directly to Foster Wheelers Resox process which converts the sulfur dioxide content to sulfur. 

The Resox process uses coal as a reducing agent to produce elemental sulfur. It was developed in Foster Wheeler Corporation s John Blizard Research Center and is the result of a research program initiated in the late 1960s. 

The RESOX process, developed by Foster Wheeler, uses anthracite coal to reduce gaseous SO2 to elemental sulfur. Development work began on the process in the late 1960s. It was tested at the Scholtz Plant (a 42 MW demonstration unit) in the 1970s and at the Lunen plant (a pilot plant) in Germany in 1974 (Rush and Edwards, 1977). The process or variations of it have been used at three plants in Japan (Steiner, 1992). 

In the RESOX process, the SO2 rich gas from the Mitsui-BF regomator is sent to a reactor where it contacts anthracite coal. The carbon in the coal reacts with the SO2 to produce elemental sulfur according to the following equation ... 

Boliden (1) An obsolete process for reducing sulfur dioxide to elemental sulfur, using hot coke. Operated in Sweden by Boliden from 1933 to 1943. See also Trail, RESOX. 

Carbonyl sulfide is an intermediate in this reaction. A mixture of sulfur dioxide and oxygen was blown into the bottom of coke-fired reduction furnace and sulfur vapor condensed from the off-gases. Trail is the location of a large mine and smelter in British Columbia. The process was originally used in the 1930s for abating air pollution from the smelter, but when the demand for sulfuric acid for fertilizer production increased in 1943 it became obsolete. See also Boliden (1), RESOX. 

RESOX A process for converting sulfur dioxide in dilute gas streams to elemental sulfur. The use of coal to remove sulfur dioxide from gas streams was described as early as 1879. Bergbau-Forschung developed... 

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