Oxygen sulfur burning

PLACE SMALL PIECE OF SULFUR IN CROOK OF BENT STRIP OF TIN CUT FROM CAN. IGNITE SULFUR WITH MATCH. LOWER INTO JAR OF OXYGEN. SULFUR BURNS WITH A BRILLIANT, BLUE LIGHT. 

FIGURE C.1 Elemental sulfur burns in air with a blue flame and produces the dense gas sulfur dioxide, a compound of sulfur and oxygen. 

Sulfur forms several oxides that in atmospheric chemistry are referred to collectively as SOx (read sox ). The most important oxides and oxoacids of sulfur are the dioxide and trioxide and the corresponding sulfurous and sulfuric acids. Sulfur burns in air to form sulfur dioxide, S02 (11), a colorless, choking, poisonous gas (recall Fig. C.1). About 7 X 1010 kg of sulfur dioxide is produced annually from the decomposition of vegetation and from volcanic emissions. In addition, approximately 1 X 1011 kg of naturally occurring hydrogen sulfide is oxidized each year to the dioxide by atmospheric oxygen ... 

How much sulfur dioxide is produced by the reaction of l.OOg S and all the oxygen in the atmosphere of the earth (If you strike a match outside, do you really have to worry about not having enough oxygen to burn all the sulfur in the match head ) This problem has the quantity of each of two reactants stated, but it is obvious that the sulfur will be used up before all the oxygen. It is also obvious that not all the oxygen will react (Otherwise, we are all in trouble.) The problem is solved just like the problems in Sec. 8.2. 

Sulfur and oxygen are burned to SO2, (Fig. 2.4, about 10% SO2 by volume) at 1000°C and then cooled to 420 °C. The SO2 and O2 enter the converter, which contains four different chambers of V2O5 catalyst. About 60-65% SO2 is converted to SO3 in the first layer with a 2-4 sec contact time. It is an exothermic reaction so the gas leaves at 600 °C. It is cooled to 400 °C with a heat exchanger (Fig. 2.5) and enters the second layer of catalyst. 

Figure 2.4 A sulfur burner where sulfur and oxygen are burned at high temperatures to make sulfur dioxide. (Courtesy of Du Pont, LaPorte, TX)...

Sulfur dioxide is made as part of the contact process for making sulfuric acid (Chapter 2, Section 2.2). Sulfur and oxygen are burned at 1000°C. Sulfur dioxide can be made by oxidation of various metal sulfides or hydrogen sulfide, or it can be made from calcium sulfate or used sulfuric acid as well. 

Berthelot45-65 burned rhombic sulfur in oxygen in a bomb at constant volume. The amounts of sulfur dioxide along with the lesser amounts of sulfur trioxide were absorbed and determined by titration with iodine exactly equivalent to the amount of sulfur burned. In another series, Berthelot used aqueous potassium hydroxide to absorb the products of combustion, titrating afterwards with iodine. His data from the two series of experiments yield, respectively, <2=69.4 and 69.1, for the reaction, S (c, rhombic) +02 (g) =S02 (g). Ferguson1 reviewed Berthelot s data and discarded the results of his second series on the grounds of unreliability of the analytical method. 

An alternative way to increase S02 concentration (and decrease furnace exit gas volume) is to feed less N2 to the sulfur burning furnace - by replacing some air with oxygen (Miller and Parekh, 2004). 

Sulfur burning s product gas composition and temperature are readily controlled by adjusting the sulfur furnace s input air/input sulfur ratio. Replacement of some of the input air with oxygen gives the process independent 02/S02, temperature and volume control. 

Heat for this reaction is mainly provided by burning molten sulfur and other fuels with preheated air (occasionally oxygen-enriched) and the 02 from Reaction (5.1). A small amount of heat is obtained from oxidizing the spent acid s hydrocarbons. Sulfur burning has the advantages that it increases S02 concentration in decomposition furnace offgas and H2S04 production rate. 

Sulfur burns in oxygen to form primarily sulfur dioxide (Figure 6-9) and only very small amounts of sulfur trioxide. 

Nearly all oxides of nonmetals react with water to give solutions of ternary acids. The Figure 6-9 Sulfur burns in oxygen oxides of boron and silicon, which are insoluble, are two exceptions. to form sulfur dioxide. 

Sulfur burning in oxygen to form sulfur dioxide. The models show elemental sulfur (Sg), and oxygen and sulfur dioxide molecules. About 50 million tons of SO2 are released to the atmosphere every year. 

Sulfur trioxide is formed in small amounts when sulfur is burned in air, althongh the principal product is sulfur dioxide. Thermodynamically, sulfur trioxide is the preferred product of sulfur and oxygen. Sulfur dioxide does react slowly with oxygen in air to produce sulfur trioxide, but the reaction is much faster in the presence of a catalyst, such as platinum. Sulfur trioxide is produced commercially by the oxidation of sulfur dioxide in the presence of vanadium(V) oxide catalyst. 

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