The crude glycerol from biodiesel production possesses low economic values and alternative ways of converting it to valuable chemicals are needed to sustain the biodiesel industry. This study aimed to investigate the production of primary alcohols and propylene glycol from glycerol through a catalytic thermochemical process without an external supply of hydrogen. The effects of reaction time, water to glycerol ratio, and doses of catalyst on glycerol conversion and alcohol yields were investigated using a batch pressure reactor and Raney nickel catalyst. The presence of alcohols and gases in the products confirmed that hydrogen was produced and was utilized in the formation of propylene glycol through hydrogenolysis. Ethanol and propylene glycol yields of up to 10.4 ( 0.2 and 33.2 ( 1.4 mol %, respectively, were observed. It was also concluded that ethanol is formed through hydrogenolysis of propylene glycol and its yield improves at extended reaction time and increased initial water content of the feed.

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Fatty acid methyl esters (FAMEs) derived from plant oils are excellent lubricant improvers, but they do not have desirable oxidative stability and cold-flow properties. This study investigated phenol hydrodeoxygenation in hexadecane and aromatic alkylation of FAMEs over a K30 montmorillonite catalyst to give phenyl-branched FAME (PBFAME) as a potential lubricant improver. The high selectivity to aromatic hydrocarbons during hydrodeoxygenation over Pd/C was likely due to the slow hydrogenation rate of phenols in hexadecane, absence of hydrogen bonding in nonpolar solvents allowing hydroxyl groups to participate in dehydration reactions, and limited diffusion of hydrogen from bulk solution to Pd sites. Isomers of methyl (methylphenyl)octadecanoate (n-MMPO) were produced during toluene alkylation of methyl oleate. The presence of both Brønsted and Lewis acid sites in K30 facilitated selective synthesis of n-MMPOs. The oxidative stability and cold-flow properties of n-MMPO were better than those of canola biodiesel.

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Biodiesel offers several environmental benefits and improvements to some fuel performance properties, but its poor oxidative stability has been a major concern. Currently, the accepted practice to improve biodiesel oxidative stability is the addition of antioxidants; numerous antioxidants have been studied but their effectiveness in inhibiting biodiesel oxidation is difficult to predict due to variation with resonance stability, solubility, reactivity, and volatility. To improve prediction efforts, this study explored the Rapid Small‐Scale Oxidation Test (RSSOT) as a means to investigate how biodiesel oxidation is affected by antioxidant concentration and temperature, and compared its results with the oxidative stability index test. A weak correlation was identified due to antioxidant variation. A kinetic model expressed in temperature and induction period was developed for biodiesel before high‐vacuum distillation (HVD), after HVD and also after HVD with three concentrations of propyl gallate (PG) and tert‐butylhydroquinone (TBHQ) antioxidants. The approach was validated by comparing collected data on the oxidation of methyl oleate with kinetic parameters found in the literature. Antioxidant concentrations from 130–930 ppm were tested, and the results revealed that the apparent activation energy of biodiesel oxidation increases with increasing concentration of primary antioxidants and decreases during vacuum distillation. When treated with an increasing concentration (130–930 ppm) of PG and TBHQ, the apparent activation energies of a vacuum distilled biodiesel changed from 108.46 ± 4.45 to 112.72 ± 1.46 kJ·mol−1 and from 77.14 ± 2.25 to 89.91 ± 2.29 kJ·mol−1, respectively. These observed trends agree with both the accepted mechanism of primary oxidation of fuels and mode of action of primary antioxidants.

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