In order to solve these problems, the use of heterogeneous catalysts has been explored. Based on their advantages: non-
corrosive, environmentally friendly, much more easily being separated from the liquid products, and designed to give
higher activity, selectivity and longer catalyst lifespan [7,8], solid base catalysts have attracted much more attention than
other kinds.This type of catalysts, used in biodiesel synthesis, includes simple metaloxide such as MgO or CaO