Sono-dispersion of calcium over Al-MCM-41 used as a nanocatalyst for biodiesel production from sunflower oil: Influence of ultrasound irradiation and calcium content on catalytic properties and performance

In this paper, the acidity of MCM-41 was improved by Al addition (Si/Al molar ratio of 50) and it was used as support in nanocatalysts with various loadings of calcium (10, 20 and 30 wt %) for biodiesel production. The catalysts were synthesized by two methods: impregnation and sono-dispersion. The synthesized samples were characterized by XRD, FESEM, EDX, TEM, BET and FTIR analysis. The XRD patterns of the samples demonstrated formation of the crystalline structure of MCM-41 and CaO. The FESEM images of the samples proved the nanoscale of catalysts and along with EDX and TEM analysis showed a better dispersion of calcium on support for ultrasonic irradiated sample compared to impregnated one. The performance of nanocatalysts was examined under constant conditions (Temperature of 70 degrees C, Methanol/Oil ratio of 12 and catalyst loading of 10 wt %). The result showed that the conversion of transesterification reaction and following that the quality of produced biodiesel was increased significantly by increasing the calcium amounts in catalysts. Furthermore, for two samples with the same amount of calcium loading, the sonicated sample showed a higher conversion. Among all of the samples Ca(30)/Al-MCM-41(U) showed the maximum conversion for biodiesel production reaction. (C) 2018 Elsevier Ltd. All rights reserved.