Reaction with elemental sulfur

Europeum generally is produced from two common rare earth minerals monazite, a rare earth-thorium orthophosphate, and bastnasite, a rare earth fluocarbonate. The ores are crushed and subjected to flotation. They are opened by sulfuric acid. Reaction with concentrated sulfuric acid at a temperature between 130 to 170°C converts thorium and the rare earths to their hydrous sulfates. The reaction is exothermic which raises the temperature to 250°C. The product sulfates are treated with cold water which dissolves the thorium and rare earth sulfates. The solution is then treated with sodium sulfate which precipitates rare earth elements by forming rare earth-sodium double salts. The precipitate is heated with sodium hydroxide to obtain rare earth hydrated oxides. Upon heating and drying, cerium hydrated oxide oxidizes to tetravalent ceric(lV) hydroxide. When the hydrated oxides are treated with hydrochloric acid or nitric acid, aU but Ce4+ salt dissolves in the acid. The insoluble Ce4+ salt is removed. 

The sulfonation of toluene proceeds via a complex scheme of elemental reactions with numerous side and consecutive reactions. Toluene sulfonic acid and sulfur trioxide can read in a consecutive process to give toluene pyrosulfonic acid, which can undergo further reactions [315,316]. Reaction of this acid with another molecule of toluene yields two molecules toluene sulfonic acid or ditolyl sulfone. In addition, toluene sulfonic anhydride may be formed via readion of toluene pyrosulfonic acid with toluene sulfonic acid. 

Sulfur Generation. During the SO2 removal step the gaseous SO2 is converted to nonvolatile sulfuric acid which remains sorbed in the carbon s pores. Conversion of this sulfuric acid to SO2 or elemental sulfur by reaction with hydrogen sulfide has been studied in bench scale. 

Microaerobic partial oxidation of the H2S in the aqueous solution to elemental sulfur by reaction with sulfur-oxidizing bacteria as in the Paques THIOPAQ/Shell-Paques gas desulfurization process (described as follows). 

Through reaction with sulfide or elemental sulfur at 215°C, lignosulfonates can also be used in the commercial production of dimethyl sulfide and methyl mercaptan (77). Dimethyl sulfide produced in the reaction is further oxidized to dimethyl sulfoxide (DMSO), a useful industrial solvent (see Sulfoxides). 

Phosphoms shows a range of oxidation states from —3 to +5 by virtue of its electronic configuration. Elemental P is oxidized easily by nonmetals such as oxygen, sulfur, and halides to form compounds such as 2 5 2 5 reduced upon reaction with metals to generate phosphides. The... 

The physical properties of elemental sulfur can be modified by its reaction with various organic and inorganic compounds. Many of the resulting sulfur products tend to have properties similar to paving asphalt (49,50). 

The pyritic sulfur in coal can undergo reaction with sulfate solutions to release elemental sulfur (see Sulfurremoval and recovery). Processes to reduce the sulfur content of coal have been sought (75). The reaction of coal and sulfuric acid has been used to produce cation exchangers, but it was not very efficient and is no longer employed. Efforts have turned to the use of hot concentrated alkaH in a process called Gravimelt. 

Figure 7-8 represents a process flow diagram of the LOCAT process. The Hi.S is contacted with the reagent in an absorber it reacts with the dissolved iron to form elemental sulfur. The reactions involved are die following ... 

Sulfur diamides (diaminosulfanes) are obtained by the action of sulfur chlorides with an aliphatic secondary amine (Eq. 10.10). ° The monoselanes Se(NR2)2 (R = Me, Et) have also been prepared. Polyselanes Scx(NR2)2 (x = 2 - 4, NR2 = morpholinyl x = 4, NR2 = piperidinyl) are formed in the reaction of elemental selenium with the boiling amine in the presence of Pb304. ... 

A rather different series of cyclic thiophos-phate(III) anions [(PS2) ]" is emerging from a study of the reaction of elemental phosphorus with polysulfidic sulfur. Anhydrous compounds... 

Zinc and cadmium tarnish quickly in moist air and combine with oxygen, sulfur, phosphorus and the halogens on being heated. Mercury also reacts with these elements, except phosphorus and its reaction with oxygen was of considerable practical importance in the early work of J. Priestley and A. L. Lavoisier on oxygen (p. 601). The reaction only becomes appreciable at temperatures of about 350° C, but above about 400°C HgO decomposes back into the elements. 

H. Reactions with Suleur and Sulfur Compounds 1. Elemental Sulfur and Inorganic Sulfur Compounds... 

Methane reacts with sulfur (an active nonmetal element of group 6A) at high temperatures to produce carbon disulfide. The reaction is endothermic, and an activation energy of approximately 160 KJ is required. Activated alumina or clay is used as the catalyst at approximately 675°C and 2 atmospheres. The process starts by vaporizing pure sulfur, mixing it with methane, and passing the mixture over the alumina catalyst. The reaction could be represented as ... 

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