TRANSACTIONS OF WAGNER 



100 



CATALYSIS IN THE INORGANIC FIELD 



capable of manifold application. No general method for guidance in selecting 

 a catalyst for a given reaction is known. 



Confining ourselves strictly to the subject assigned to us tonight, — 

 "Catalysis in the Inorganic Field," — three great processes of chemical indus- 

 tries demand attention. All three involve the use of that great reservoir of 

 raw material, the atmosphere. 



The first, Deacon's process, is the most successful method for producing 

 chlorin without the use of a manganese compound. It is well to compare the 

 non-catalytic process with Deacon's process, by aid of equations: 



MnOa + 4HCI -^ MnCl2 + 2H2O + CI2 

 O2 + 4HCI -^ 2H2O + CI2 



The catalyst is cupric chlorid at 400°, used on pumice, broken brick or other 

 porous refractory material as a support. Numerous other substances catalyze 

 this change, less effectively, however, than cupric chlorid; for instance, ferric 

 chlorid, platinum, chromic oxid, nickel chlorid. 



To poisons, cupric chlorid is one of the most sensitive catalysts. Arsenous 

 and arsenic oxids and sulfur trioxid must be removed from the gases, as well 

 as all moisture. Temperatures above 460° cause the catalyst to volatihze too 

 rapidly, and temperatures below 400° give too low a yield. The "decom- 

 posers," therefore, as the chambers that contain the catalyst are called, are built 

 in separate compartments each of which may be emptied and recharged with- 

 out discontinuing the flow of gas through the others. 



The second of the great chemical industrial processes for consideration is 

 the manufacture of sulfuric acid. Sulfuric acid is probably the most important 

 of aU chemicals, because of its extensive use in numerous manufacturing proc- 

 esses. In 1740 Ward began manufacturing this acid, in England, by burning 

 sulfur and niter together and condensing the vapors in glass vessels containing 

 water. These were soon replaced by lead vessels, and later steam was intro- 

 duced instead of water, and nitrogen oxids prepared by the decomposition of 

 niter in a separate vessel and air were also introduced. For comparison, the 

 reactions in these two processes may be written : 



(i) 2KNO3 + S -^ SO3 + K2O + 2NO 



(2) 3O + S -> SO3 



although it is well known that neither reaction is as simple as represented in 

 these equations. They serve, however, to emphasize the greater simplicity 



