Effect of Extra-Framework Cations of LTL Nanozeolites to Inhibit Oil Oxidation

Abstract

Lubricant oils take significant part in current health and environmental considerations since they are an integral and indispensable component of modern technology. Antioxidants are probably the most important additives used in oils because oxidative deterioration plays a major role in oil degradation. Zeolite nanoparticles (NPs) have been proven as another option as green antioxidants in oil formulation. The anti-oxidative behavior of zeolite NPs is obvious; however, the phenomenon is still under investigation. Herein, a study of the effect of extra-framework cations stabilized on Linde Type L (LTL) zeolite NPs (ca. 20 nm) on inhibition of oxidation in palm oil-based lubricant oil is reported. Hydrophilic LTL zeolites with a Si/Al ratio of 3.2 containing four different inorganic cations (Li+, Na+, K+, Ca2+) were applied. The oxidation of the lubricant oil was followed by visual observation, colorimetry, fourier transform infrared (FTIR) spectroscopy, 1H NMR spectroscopy, total acid number (TAN), and rheology analyses. The effect of extra-framework cations to slow down the rate of oil oxidation and to control the viscosity of oil is demonstrated. The degradation rate of the lubricant oil samples is decreased considerably as the polarizability of cation is increased with the presence of zeolite NPs. More importantly, the microporous zeolite NPs have a great influence in halting the steps that lead to the polymerization of the oils and thus increasing the lifetime of oils.

Zeolite Nanocrystals Protect the Performance of Organic Additives and Adsorb Acid Compounds during Lubricants Oxidation

“…The LTL nanozeolite used in this study is prepared free of organic structural directing agents, thus avoiding energy expenditure and CO 2 release resulting from high temperature calcinations. This zeolite was selected due to the high efficiency towards adsorbing products of lubricant oxidation [22,23,24,26], absence of Brønsted or Lewis acidity [26], hence cannot catalyze the oxidation of lubricants, in addition to the absence of toxicity on the living cells [27]. XRD pattern of the prepared zeolite reveals broad Bragg peaks typical for small nanoparticles with shifts corresponding to pure LTL structure in absence of other phases (Figure S1).…”

“…The negative values recorded for samples SA-C2 and SA-C3 can be attributed to the partial adsorption of PIB-succinimide that presents C=O vibrations in the same region. Indeed, the FTIR spectra of the LTL zeolite samples separated from the lubricants revealed the presence of PIB-succinimide vibrations vibrations [23,32] (Figure 7 and Figure S10). The ratio (1705/1770) between the two bands at 1705 cm −1 and 1770 cm −1 corresponding to this additive is found to be higher in the zeolite powder samples extracted from oxidized lubricants than in the fresh lubricants, suggesting the absorption of additional “C=O” containing species from oxidation products on the zeolite.…”

“…For instance, while the proton (H) form demonstrate strong Lewis and Brønsted character, the cationic zeolites present a basic character suitable to neutralize weak acids [20,21]. LTL and FAU (faujasite) nanosized zeolites have already demonstrated high capabilities as antioxidants for the preservation of palm oil during the early stages of oxidation [22,23,24]. The primary oxidation products “peroxides” are stabilized by the zeolite charge compensating cations with a strong influence driven by the type of cation used.…”

Ultrasmall Zeolite L Crystals Prepared from Highly Interdispersed Alkali‐Silicate Precursors

“…Syntheses of zeolite L tend to produce approximately 3 μm crystals (Figure S1). Methods for generating small zeolite L crystals often require long crystallization time (e.g., 18–48 h) and/or the use of microwave synthesis or unconventional reagents (e.g., aluminum foil and rice husk) that are not readily employed in commercial processes. In this study, we observe that the optimization of growth mixtures using potassium silicate yields ultrasmall zeolite L crystals with average sizes that are smaller than the majority of reported cases (Table S2 and Figures S3–S8).…”

Monitoring of oxidation behavior in mineral base oil additized with biomass derived antioxidants using FT-IR spectroscopy

“…11 Among the antioxidants, various natural and synthetic materials have been recommended for oil formulations. [12][13][14][15][16][17][18] However, most of the synthetic antioxidants developed till date has been found to be suffered from antagonism and become ineffective in maintaining the oil integrity. 19,20 Hence, for modern formulations, the use of natural antioxidants have been found to be more feasible owing to the benets of their readily availability, environment/eco-friendly composition, cost effectiveness, synergistic effect to properties other than their antioxidant character, etc.…”