BO-75-07-1 -- Alkylbenzenes as Refrigeration Oils PDF

Alkylbenzenes have been in limited use as refrigeration oils for some time, and alkylbenzene-based refrigeration oils were commercialized in the United States in 1974.

There are two basic types of alkylbenzenes, branched and linear (Fig. 1). The products are synthesized by reacting an olefin or a chlorinated paraffin with benzene in the presence of a catalyst. Catalysts commonly used for this reaction are aluminum chloride and hydrofluoric acid.

In addition to the type of olefin or chlorinated paraffin used, the structure of alkylbenzene is affected by the catalyst (AlC1 3 or HF) as well as other processing variables. The structures shown are typical ones for branched and linear alkylbenzenes, but other structures are also present.

After removal of the catalyst, the product is normally distilled into three fractions (Fig. 2). It is possible to affect the relative size of these fractions by adjusting the molecular weight of the side chain (olefin or chlorinated paraffin) as well as by changing other variables. Therefore, the amounts of the middle and heavy fractions produced depend to a large extent on demand and economics.