Technology for rerefining used lube oils applied in Europe: a review

Abstract

The European oil rerefining industry is comprised of 28 plants treating waste oil, which represent one‐third in volume of the total European market for lubricants. The biggest European rerefineries with capacity greater than 40 000 tons/year apply various technologies for recycling of used oils from different sources. Used oil recycling technology has undergone significant changes over the past decade. With the newly developed rerefining technologies it is possible to produce higher quality base oil compared with the traditional and old acid clay methods. Currently in Europe the following re‐refining methods are widely used: solvent extraction (N‐methyl‐2‐pyrrolidone (Germany), Interline process (United Kingdom, Spain)); combined vacuum distillation and solvent extraction (Vaxon process (Denmark, Spain); hydroprocessing (Hylube process (Germany)); combined thin film evaporation and hydrofinishing (CEP process (Finland)); combined thermal de‐asphalting and hydrofinishing (Revivoil process (Italy, Poland, and Spain)). The majority of applied technologies in Europe is appropriate for rerefining of synthetic lubricating oils, which currently are replacing the conventional mineral lube oils due to their enhanced performance characteristics. However, for the rerefining technologies applying alkaline treatment (CEP, Vaxon) and hydrofinishing step (Cyclon, Snamprogetti, Revivoil) the amount of synthetic or semi‐synthetic oils based on esters in the feedstock should be eliminated, since these oils are less stable under alkali and hydrofinishing conditions. © 2013 Society of Chemical Industry

The base-catalyzed transformation of tetramethyldisiloxane: influence of reaction media

“…Sodium ions and alkoxy groups attached to the silicon atom form linear sodium siloxanolates, which depending on the reaction conditions could be a final solid product or could be consumed in cyclic siloxane monomer formation. Since potassium hydroxide is widely used in the industry, its influence on the TMDS transformation reaction was evaluated in the present work. The reaction was carried out at different temperatures (Table , entry 1).…”

“…In the petroleum industry, silicon originates mainly from the use of polymethylsiloxane‐based antifoaming agents in industrial oils, in which the amount of silicone can reach about 200 ppm. Some oil re‐refining processes such as those of Vaxon, Chemical Engineering Partners (CEP), and Sotulub, apply alkaline pretreatment of used oil . The process usually proceeds at low temperatures and under alkali conditions.…”

“…In our previous report, sodium hydroxide was applied as an alkali agent and the reaction was studied in the temperature range 60–110 °C for 3 h and longer duration times. In the present work the same reaction was catalyzed by potassium hydroxide widely used in the industry . The influence of the alkali type on the reaction performance was elucidated via comparison of the reaction rates and product distributions in the mixtures with sodium and potassium hydroxides.…”

Recent advances in waste lube oils processing technologies

“…Several methods have been widely used in waste oils re‐refining in Europe, such as solvent‐extraction, combined vacuum distillation and solvent extraction, hydro‐processing, combined thin film evaporation and hydrofinishing, and combined thermal de‐asphalting and hydrofinishing . However, the overall steps require a relatively high operating cost and high energy consumption .…”

“…Zhang et al [62] reported that the hetero-structured TiO 2 /SnO 2 nanofibers exhibited a much higher degradation rate of methylene blue, rhodamine B, and 4-chlorophenol in photocatalytic test, while Song et al [63] found that C-dots/WO 3 possessed stronger photocatalytic capability and excellent recyclability for photocatalytic elimination of Rhodamine B. Several methods have been widely used in waste oils rerefining in Europe, such as solvent-extraction, combined vacuum distillation and solvent extraction, hydro-processing, combined thin film evaporation and hydrofinishing, and combined thermal de-asphalting and hydrofinishing [64]. However, the overall steps require a relatively high operating cost and high energy consumption [21].…”