Alkyl-tetralin base oils synthesized from coal-based chemicals and evaluation of their lubricating properties

Abstract

Naphthenic base oil is an important lubricating base oil and very scarce in the global petroleum resources. Herein, a series of alkylated tetralin fluids similar to naphthenic base oils were produced by the alkylation of tetralin and α-olefins (n-hexene, n-octene, n-decene) with ionic liquid Et3NHCl/AlCl3 as the catalyst, where the applied raw materials are totally derived from the coal chemical industry. The product composition could be controlled by adjusting the feeding ratio of tetralin and olefin. The synthetic fluids were evaluated as lubricating base oils to reveal the structure–property correlations. Their principal physicochemical and tribological properties depend on the chain-length of α-olefins and the number of alkyl groups onto the aromatic rings. Bis-(octyl- or decyl-) alkyl tetralin exhibited good properties in terms of viscosity, thermo-oxidation stability and pour point, as well as friction-reducing and anti-wear performance, showing great potential for producing naphthenic base synthetic oils from coal-based chemicals.