Some Industrial Hydrogenation Processes

The water-gas shift reaction (eq.l) represents a very important step in some industrial catalytic processes like production of hydrogen, ammonia and other bulk chemicals. The basic informations concerning water-gas shift reaction and catalysts used, were reviewed by D.S.Newsome [1] and M.V. Twigg [2]. 

Elemental phosphoms from the electrothermal process is a distilled product of high purity and yields phosphoric acid pure enough for most industrial uses without any further treatment. The main impurity is ca 20—100 ppm arsenic present in the phosphoms as the element and in the phosphoric acid as arsenious acid. To remove the arsenic, the phosphoric acid destined for food, pharmaceutical, and some industrial-grade appHcations is treated with excess hydrogen sulfide, filtered, and blown with air to strip out excess H2S. This treatment generally reduces the arsenic content of the phosphoric acid to less than 0.5 ppm. The small amount of filter cake is disposed of in approved chemical landfills. 

When hydrogenation reactions cease to be experimental and enter the stage of industrial development, the cost of the hydrogenation process becomes important. Some of the factors that enter into the determination of this cost are considered here. 

Thus, it is seen that the same iron is used continu-isly, and steam and blue water gas are the two regents consumed. Such is the chemical outline of the on Contact process however, in practice, the process somewhat more complex and very much less efficient lan either the Electrolytic process or the Badische ocess, both of which are described at a later stage, nor in the hydrogen produced be regarded as so satisfactory tr some industrial purposes, such as fat hardening, as lat made by the other two processes. 

Elemental sulfur1-4 occurs naturally in association with volcanic vents and, in Texas and Louisiana, as underground deposits. The latter are mined by injecting air and superheated water, which melts the sulfur and carries it to the surface in the return flow (the Frasch process). Most of the sulfur used in industry, however, comes as a by-product of the desulfurization of fossil fuels. For example, Albertan sour natural gas, which often contains over 30% (90%, in some cases) hydrogen sulfide (H2S), as well as hydrocarbons (mainly methane) and small amounts of C02, carbonyl sulfide (COS), and water, is sweetened by scrubbing out the H2S and then converting it to elemental S in the Claus process.5 The Claus process is applicable in any industrial operation that produces H2S (see Section 8.5) it converts this highly toxic gas to nontoxic, relatively unreactive, and easily transportable solid sulfur. 

Instead of decomposing sodium chloride with sulphuric acid in order to obtain sodium sulphate, attempts have been made to prepare hydrogen chloride from sodium chloride, leaving a by-product of greater commercial value than sodium sulphate. Some of these processes furnish chlorine—q.v. Most of the proposals have either not been applied at all on an industrial scale, or else have had a very brief industrial life. For example, it has been proposed to heat an intimate mixture of sodium chloride and clay with steam, and to obtain sodium silicate and hydrogen chloride as products of the main reaction. A. Gorgeu13 has shown that clay with about 35 per... 

Fluorocarbons (FCs) Organic compounds analogous to hydrocarbons in which one or more hydrogen atoms are replaced by fluorine. FCs were once used in the United States as a propellant for domestic aerosols and are now found mainly in coolants and some industrial processes. FCs containing chlorine are called chlorofluorocarbons (CFCs). These are believed to be modifying the ozone layer in the stratosphere and are responsible for allowing more harmful solar radiation to reach the Earth s surface. 

Another promising class of copper(II) S-diketonates has been synthesized by Toscano and Welch by substitntion of a carbon atom by silicon Copper(II) sila-/ -diketonates and their fluorinated derivatives have greater volatility than the corresponding carbon-hydrogen analogues and some of them exist as liqnids or low melting solids, the preferred state for industrial CVD processes. Two different deposition modes of this class of precursors are also discussed (Scheme 3). ... 

---