*3.4. Catalyst Selection*

Catalyst selection incorporated several fundamentals presented by Grasselli [14] such as the need for lattice oxygen, metal oxygen bonds and using the appropriate host structure. Lattice oxygen is a versatile and more selective oxidizing agent than gaseous dioxygen. The basic idea is to use the metal oxygen as a reactant such that only desired products are favored during the oxidation of hydrocarbons. Following the need for lattice oxygen, the metal oxygen bond type needed was explored. If the bond is too strong, no reaction will occur. Conversely, undesired overoxidation may occur prevalently. The host structure should be pliable, able to contain lattice oxygen and be reduced without structural collapse. Taking these properties into consideration, bismuth molybdate, Bi(MoO4)3, and vanadium molybdate, VMo3O11, catalysts were selected for R-101 and R-102. These catalysts reported high selectivities towards acrolein and acrylic acid [15].
