Transesterification of Soybean Oil to Biodiesel by Using Heterogeneous Basic Catalysts

Abstract

Biodiesel production has increased greatly in recent years, because of the less-detrimental effects of this fuel on the environment, compared to a conventional diesel obtained from petroleum. This work investigates the possibility of using MgO and calcined hydrotalcites as catalysts for the transesterification of soybean oil with methanol. The achieved experimental data show a correlation not only with the catalysts basicity, but also with its structural texture. However, the structural texture of the examined catalysts is dependent on both the precursor and the preparation method. At least four different types of basic sites have been individuated on the surface of MgO and calcined hydrotalcite catalysts. The strongest basic sites (super-basic) promote the transesterification reaction also at very low temperature (100°C), while the basic sites of medium strength require higher temperatures to promote the same reaction. Ultimately, all the tested catalysts are resistant to the presence of moisture in the reaction environment.

The effect of sodium on the catalytic activity of ZnO–Al2O3/ZSM-5 and SnO–Al2O3/ZSM-5 for the transesterification of vegetable oil with methanol

“…In order to minimize or avoid problems associated with the homogeneous catalytic process, attempts have been made to develop heterogeneous catalyst systems [2][3][4][5][6][7]. The catalytic activity of the heterogeneous base catalyst, in the transesterification of soybean oil, shows a striking correlation with basic strength [5,[8][9][10].…”

“…The catalytic activity of the heterogeneous base catalyst, in the transesterification of soybean oil, shows a striking correlation with basic strength [5,[8][9][10]. Thus, most heterogeneous catalysts for biodiesel production contain alkali or alkali earth cations [4,5,8,9,[11][12][13][14][15][16][17][18][19]. However, most of the catalysts experienced deactivation, by leaching of the alkali species from the heterogeneous catalysts to reaction medium [1,20].…”

“…Several studies reported that Mg-Al hydrotalcites [4,5,21] and metal oxides (Al2O3-SnO, Al2O3-ZnO) [22] were active for the transesterification of vegetable oils with methanol at a relatively low reaction temperature. Although sodium hydroxide or sodium carbonate compounds were used in these catalyst preparations, the catalytic activity and deactivation behavior of the metal oxide catalysts were reported as originating from metal oxides (Al2O3-SnO, Al2O3-ZnO) or Mg-Al hydrotalcites sites [4,5,21,22]. As a result, there are conflicting reports of the catalytic activity of the metal oxides catalysts at low temperature for transesterification of vegetable oil and methanol.…”

Biodiesel and FAME synthesis assisted by microwaves: Homogeneous batch and flow processes

“…A continuous transesterification process would be a good opportunity to reduce production costs [11].…”

Catalysing sustainable fuel and chemical synthesis

“…Hydrotalcites are another class of solid base catalysts that have attracted recent attention because of their high activity and robustness in the presence of water and FFA [118,119].…”