Study on the preparation, characterization of a novel solid Lewis acid Al3+-SO42−/MWCNTs catalyst and its catalytic performance for the synthesis of biodiesel via esterification reaction of oleic acid and methanol

摘要: Abstract A novel solid Lewis acid catalyst Al 3+ -SO 4 2− /MWCNTs was prepared by impregnating multi walled carbon nanotubes (MWCNTs) with concentrated sulfuric and . The physical chemical properties of characterized X-ray diffraction, transmission electron microscopy, Raman spectroscopy, fluorescence NH 3 temperature programmed desorption, photoelectron spectroscopy pyridine adsorption IR spectra. catalytic activities SO /MWCNTs, /SWCNTs, /C were compared when they respectively applied for the synthesis biodiesel via esterification reaction oleic methanol. Results showed that had highest activity: conversion ratio reached 95% 65 °C, mass to reactants 0.9 wt% molar methanol 12:1 after 7 h. high activity can be ascribed flow escape electronic is very easily in tubular structure MWCNTs since it has low C1s binding energy. It will stimulate a strong interaction between , accompanied formation stable coordination bond, which increased crystallization degree improved combination stability MWCNTs. In addition, S O band exert strong induced effect, leads increasing valence layer density element, reduces shielding effect outer electrons on core increases energy electrons. directly affects state changes enhances absorption capacity imbalance system. Eventually, changed original acidity enhanced its acidity. Hence, site mainly comprised acid, favorable avoiding occurrence hydration Bronsted active sites.