246 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1947 



through the bond where the hydrogen atom was removed, alkylation 

 has been accomplished. The broad definition of this term leaves us 

 nowhere, but one of the specific alkylation processes in which interest 

 is at a high pitch at the present time unites isobutane (a branched- 

 chain compound) with a butane (unsaturated branched- or straight- 

 chain compound) to produce practically pure iso-octane. The opera- 

 tion is carried out at low pressure and low temperature, and requires 



N -;;v.^' f 



Figure 4. — Petroleum-ization— 1940, Diagram indicates the complexity of the 

 refiner's problem in properly selecting the processes for the several products 

 and stages of refining best suited for his specific crudes. 



a catalyst. Another example is the process which produces cumene. 

 In this process propylene is reacted with benzol to produce isopropyl 

 benzene, a valuable aviation blending agent. 



Desulfurization. — In general, this term is self-defining, but here it 

 will be considered as applying to the removal of sulfur from material 

 within the gasoline boiling range. Chemical desulfurization, using 

 either sulfuric acid or caustic soda, has been practiced for many years. 

 There is, however, a definite feeling that destructive chemical desul- 

 furization is on the way out; so, for the purpose of this sunamary — 



