DEHYDRATION CATALYSTS,PARTICULARLY FOR THE DEHYDRATION OF DIOLS

1355705 Pyrophosphates COMPAGNIE FRANCAISE DE RAFFINAGE 19 April 1971 [16 April 1970] 58053/73 Divided out of 1355704 Heading C1A [Also in Division B1] Neutral pyrophosphate of at least one metal selected from lithium, sodium, strontium and barium is prepared by a method which comprises mixing at least one acid orthophosphate of at least one metal selected from lithium, sodium, strontium and barium with at least one neutral pyrophosphate of at least one metal selected from lithium, sodium, strontium and barium, forming an extrudate from the resulting mixture, and drying and calcining the extrudate in air in order to convert the acid orthophosphate into neutral pyrophosphate. Both the orthophosphate and pyrophosphate are preferably in powdered form when mixed. As exemplified, a mixture of sodium pyrophosphate, Na 4 P 2 O 7 , and lithium sodium double pyrophosphate is prepared by a procedure wherein equal amounts of hydrated disodium orthophosphate and lithium sodium double pyrophosphate are mixed, the resulting mixture is crushed and then wetted with water, and the resulting paste is extruded, dried for 18 hours at 110‹ C. and then calcined for 2 hours at 500‹ C. The neutral pyrophosphate may be used as catalyst in the dehydration of vicinal and non- vicinal diols. Reference is made to Specification 1,288,662.