Nanosized molecular sieves utilized as an environmentally friendly alternative to antioxidants for lubricant oils

Abstract

Lubricants play a significant part in current environmental considerations since they are an integral and indispensable component of modern technology. The production, application and disposal of the lubricants have to follow increasingly strict requirements for protecting the environment and living organisms. In this respect, molecular sieve (LTL type zeolite) is investigated as a potential environmentally friendly alternative to traditional antioxidant additives for lubricant oils. Accelerated oxidation experiments using pure base oil and additivated base oil in the presence of the LTL molecular sieve are carried out in parallel, and the oxidation processes are monitored by FT-IR spectroscopy, spectrophotometry, chromatography, total acid number (TAN) and Karl-Fischer titrations. The LTL molecular sieve shows the potential of slowing down the oxidation rate of the oils and also resulted in a lower rate of production of solid polymeric residues. In addition, it is demonstrated that the mode of action of the LTL molecular sieve is different in nature in comparison to the organic counterparts (original antioxidants). The LTL type molecular sieve controls the water generation, while the amount of carboxylic acids is only affected in a modest amount. Apparently during the continuous oxidation of the lubricants, the zeolite adsorbs not only carboxylic acids but also other acid products such as alcohols, ketones and aldehydes. And more importantly, the LTL type molecular sieve has a greater influence in halting the steps which lead to the polymerization of the oils.