“…Considering the great amount of ethanol that has been produced and the possible reduced ethanol applications, it is highly desirable to upgrade ethanol to valueadded chemicals, advanced fuels or materials such as hydrogen, butanol, aromatic compounds, aviation fuels and monomers that cannot be replaced by electric engines. [203][204][205][206][207][208][209][210][211] (2) Homogeneous catalysts vs. heterogeneous catalysts. Homogeneous catalysts, usually organometallic complexes, generally demonstrate high activity, selectivity, and efficiency under mild reaction conditions.…”