Dilute sulfonic acid post functionalized metal organic framework as a heterogeneous acid catalyst for esterification to produce biodiesel

• Published in: Fuel (Guildford) Vol. 266; p. 117149
• Main Authors: Liu, Fengsheng, Ma, Xiaoling, Li, Hui, Wang, Yangyang, Cui, Ping, Guo, Min, Yaxin, Helian, Lu, Wanpeng, Zhou, Shoujun, Yu, Mingzhi
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 15.04.2020; Elsevier BV
• Subjects: Acid catalyst; Biodiesel; Biodiesel fuels; Biofuels; Catalysts; Chemical synthesis; Diesel; Dilution; Esterification; Fourier analysis; Fourier transforms; Infrared analysis; Infrared spectroscopy; Metal-organic frameworks; Methanol; MIL-100(Fe); Oleic acid; Pyridines; Reagents; Scanning electron microscopy; SO3H; Spectrum analysis; Sulfonic acid; Sulfuric acid; Thermogravimetry; Titration; Wastewater; X ray powder diffraction; Acid catalyst; MIL-100(Fe); Biodiesel; Esterification; SO3H
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2020.117149

•A green and stable catalyst was prepared by dilute sulphuric acid and MIL-100(Fe).•Lewis and Brønsted acid site were detected in MF-SO3H.•MF-SO3H achieved 95.86% conversion of oleic acid with methanol in esterification.•Catalyst reusability is promising for five cycles without obvious activity loss. In order to synthesize the efficient heterogeneous acid catalyst for biodiesel production, concentrated sulfuric acid (>18.4 mol/L) is commonly used as sulfonated reagent to anchor sulfonic acid group (SO3H) on a support. However, large amount of wastewater is generated while the concentrated sulfuric acid removed by washing. In this study, a green and highly stable sulfonated catalyst is prepared by using MIL-100(Fe), which is functionalized by the dilute sulfonic acid. The obtained catalyst is adopted to catalyze the esterification of methanol and oleic acid. Meanwhile, it is characterized by thermogravimetry analysis (TG), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), pyridine FTIR spectroscopy (Py-FTIR), scanning electron microscope (SEM), Hammett indicator titration and nitrogen adsorption-desorption. The maximum esterification conversion of 95.86% is achieved at molar ratio of methanol to oleic acid of 10, catalyst amount of 8 wt% (referred to oleic acid mass) at 70 °C within 2 h. More importantly, the catalyst could be repeatedly used for six cycles without significant activity loss.