Bifunctional Co3O4/ZSM-5 Mesoporous Catalysts for Biodiesel Production via Esterification of Unsaturated Omega-9 Oleic Acid

Abstract

In the present work, two sets of the Co/ZSM-5 mesoporous catalysts with different acidity and Co loadings varying from 1 to 5 and 10 wt% were prepared using mesoporous ZSM-5-A (Si/Al = 50) and ZSM-5-B (Si/Al = 150) as support. X-ray diffraction (XRD) analysis showed that the Co3O4 phase was formed in the surface of catalysts and the reducibility of Co3O4 nanoparticles on the ZSM-5-B was greater in comparison with that on the ZSM-5-A solid. In situ FTIR of pyridine adsorption characterization confirmed that all of the Co/ZSM-5 catalysts contained both Lewis (L) and Brønsted (B) acid sites, with a relatively balanced B/L ratio ranging from 0.61 to 1.94. Therefore, the Si/Al molar ratio in ZSM-5 affected both the surface acidity and the cobalt oxide reducibility. In the esterification of unsaturated omega-9 oleic acid with methanol, under the optimal reaction conditions (temperature 160 °C, catalyst concentration 2 g/L, methanol/oleic acid molar ratio 30, and reaction time 180 min), the biodiesel selectivity reached 95.1% over the most active 10 wt% Co/ZSM-5-B catalyst. The higher esterification activity of the Co/ZSM-5-B catalysts can be correlated with the greater amount of B and L acid sites, the balanced B/L ratio, and the higher reducibility of Co3O4 nanoparticles. The oleic acid esterification reaction followed the bifunctional mechanism of combining metal function (dispersed Co3O4 with a greater reducibility) with the acidity function (both B and L acid sites with a relative balanced B/L ratio) on the catalysts, which may help in providing a deep understanding of the esterification pathways and benefiting the design of novel bifunctional catalysts for biofuel production.

Efficient and Stable Rice Husk Bioderived Silica Supported Cu2S-FeS for One Pot Esterification and Transesterification of a Malaysian Palm Fatty Acid Distillate

“…The remaining powder was rinsed with an analytical grade of ethanol and acetone. Repetition of the above procedure was then performed with the remaining loading metal concentrations (2,5,8,10,12, and 15 wt.%).…”

“…Biodiesel, comprised of long-chain fatty acid methyl esters (FAME), has been drawing considerable interest in recent years as a promising option for diesel derived from petroleum [1][2][3]. Its use has the potential to counter the growing lack of energy fuel and additionally offers a more environmentally friendly and renewable solution to the pollution caused by the utilisation of its petroleum-based equivalent [4][5][6][7].…”

Low-cost diatomite supported binary transition metal sulfates: an efficient reusable solid catalyst for biodiesel synthesis

“…[15][16][17] Heterogeneous catalysts, including heterogeneous acids and bases, are considered as a potential alternative because of their easy separation from the reaction mixture, good stability, excellent reactivity and easy recovery. 16,[18][19][20][21] However, waste vegetable oils and fats usually contain high levels of fatty acids due to them becoming rancid during collection and processing. When employing base catalysts, these fatty acids cannot be transformed into fatty acid alkyl esters (biodiesel) by esterication, resulting in low yields.…”

“…15–17 Heterogeneous catalysts, including heterogeneous acids and bases, are considered as a potential alternative because of their easy separation from the reaction mixture, good stability, excellent reactivity and easy recovery. 16,18–21…”

Synthesis of Silicotungstic Acid/Ni-Zr-O Composite Nanoparticle by Using Bimetallic Ni-Zr MOF for Fatty Acid Esterification

“…Heterogeneous catalytic approaches have distinct advantages over homogeneous catalytic approaches because the heterogeneous catalysts with excellent reusability can be easily separated from the reaction mixture [13]. Currently, various types of heterogeneous catalysts have been reported for biodiesel production, such as zeolite [14], Amberlyst [15], acidic ionic liquids [16], and heteropoly acid [17,18]. However, in some heterogeneous catalysts, the leaching of active components is found in the reaction process, leading to a decrease in stability [19].…”