The Catalytic Dehydrochlorinations of 1, 1, 2-Trichloroethane and 1, 2-Dichloropropane on Various Metal Fluorides

Abstract

The catalytic dehydrochlorinations of 1, 1, 2-trichloroethane(TCE) and1, 2dichloropropane (DCP) were studied at 3000C and 250"C, respectively on various metal fl uorides. The catalytic activities were found to be in order of AIF3 MgF2CaF2 =t CrFs ZrF4 LiF (Figs. 1, 2). Except for MgF2 this order corresponded, to that of the catalytic dehydroclorination of 1, 1, 1- trichloroethane. The selectivity for TCE dehydrochlorination showed that all of examined metal fluorides belonged to a solid acid group typified by silica-alumina(Fig.3).
The calytic activity of aluminum fluoride decreased with calcination temperature. And that ofaluminum fluoride which had been poisoned NaOH solution decreased with the concentration of NaOH, and a relation was found between its activity and acidity.br In the MgF2-AIF3 system, the catalytic activity for DCP dehydrochlorination showed maximum at 13 and 90 mol% AIFs, and minimum at about 60 mol% AIFs, which corresponded to the acid amount Ho +4.8.Some disagreements observed may be due to theinteraction of MgF2 considerably and produced HCI.
Infrared absorption spectra of pyridine adsorbed on AIF3 showed that AIFg has bothj Br6nsted (1540cm-1)andLewis (1450 and 1490cm-i) type acid sites.