GB827623A - Preparation of drying oils by the polymerization of the products from the codehydrogenation of butane and ethyl benzine - Google Patents

Abstract

A unitary process for preparing a synthetic drying oil comprises catalytically dehydrogenating a mixture of ethylbenzene and a hydrocarbon chosen from n-butane, butene-1 and butene-2, to form a mixture containing substantial quantities of butadiene and styrene, subjecting this mixture without separation to polymerization in the presence of a finely divided alkali metal to form an oily polymer, separating unreacted materials from the polymer and recycling them to the dehydrogenation zone. In a preferred embodiment, a mixture of n-butane and ethylbenzene is introduced through line 1 together with recycle n-butane, butenes and ethylbenzene from line 2 and heated to 500-1150 DEG F. in a preheater 3. The mixture is then dehydrogenated <PICT:0827623/IV (a)/1> in unit 5 at a pressure of 2-10 pounds per square inch, and a temperature of 1150-1450 DEG F. over a chromia-alumina type catalyst or a mixture of magnesium oxide, iron oxide, copper oxide and potassium oxide, and the products after quenching in a tower 7 and cooling in a heat exchanger 9 pass through a series of compression stages 11 where the major part of the product is liquefied and withdrawn through line 12. After stripping off light gases the liquefied product optionally with the addition of an ether such as dioxane-1,4, diethyl ether, methylal, ethylal, methylacetal, or t-butyl methyl ether or an alcohol such as isopropanol, isobutanol, isopentanol, secondary butanol and tertiary butanol is passed over a polymerization catalyst such as sodium, potassium, lithium, caesium, rubidium or their alkyl compounds in vessel 20. The catalyst may be prepared by dispersing the molten metal in a hydrocarbon such as Varsol or ethyl benzene and cooling with stirring. Polymerization may be effected in several stages. The crude product is neutralized with ammonia in vessel 27 and the product filtered with the aid of silica gel, clay or charcoal in filter 30. The required polymer which is a colourless to yellow liquid is withdrawn through pipe 34 and unreacted vapours are recycled through pipe 33. Specifications 704,607 and 766,225 are referred to.