PURPOSE: To enable the recovery of an electrical insulating oil of superior low temperature characteristics by adding alkylbenzene to a by-product oil for reaction under the existence of a ZSM-5 type synthetic zeolite catalyst.
CONSTITUTION: A by-product oil containing diphenylmethane and 1,1-diphenyl ethane used as a raw material oil is directly recovered from an alkylation product via distillation or normally via vacuum distillation. Or a by-product oil within a wide boiling point range is once recovered and again distilled. Then, an alkylbenzene having at least one alkyl group of 1 to 4 carbon atoms is made in contact therewith under the existence of a ZSM-5 type synthetic zeolite catalyst and thereafter the by-product is recovered from a reaction mixture, thereby obtaining a cut mainly containing 1,1-diphenylethane and other diarylalkane. According to the aforesaid process, it is possible to manufacture an electrical insulating oil of superior low temperature characteristics with the synergetic effect of each component of unreacted 1,1-diphenylethane and diarylalkane.
ENDO KEIJI
DOI HIDEYUKI
SATO ATSUSHI
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