Relation Of Coal Gasification To The Production Of Chemicals

FOR the purposes of this discussion, the direct gasification of coal means the of hydrogen and carbon monoxide by the well-known water-gas reaction. Chemicals or other synthetic products may be made from these constituents of the gas and under such circumstances the gas is called synthesis gas. Or, if the same gas is used as a fuel, it is called blue gas or water gas. This type of gas has usually been made from coke, especially in this country, and has been used both for fuel purposes and for manufacture of chemicals. Recently, natural gas has gained the ascendancy as a source of synthesis gas for manufacture of chemicals because of its relative cheapness. As natural gas becomes less readily available and more expensive, coal will take its place as a raw material for the preparation of synthesis gas. This substitution will probably take the form of direct gasification of the coal rather than the present two-step procedure of carbonization of the coal followed by gasification of the coke. The chief reason for this probability is the intensive research now being carried on by several organizations to develop successful and economical processes for the direct gasification of coal, which is a considerably cheaper fuel than coke. In the following pages an attempt has been made to predict the chemicals that will result from this future production of synthesis gas by the direct gasification of coal. CHEMICAL REACTIONS OF SYNTHESIS GAS Given the proper conditions, there are many chemical reactions leading to production of useful products that can be carried out with this mixture of hydrogen and carbon monoxide. These many reactions may be grouped into three classes: (1) interaction of hydrogen and carbon monoxide, possibly with addition of other reactants; (2) reaction of hydrogen with various substances; (3) reaction of carbon monoxide with various substances. Thus sometimes hydrogen and carbon monoxide are utilized together in the same chemical reaction while in other instances only the hydrogen or only the carbon monoxide is required as a reactant. Fortunately, practical methods are available for securing either hydrogen or carbon monoxide from synthesis gas, some of which are also applicable for changing the ratio of these two constituents in the gas when that is desirable.