Performance of Mo-Bi-Co-Fe-K-O catalysts prepared from a sol–gel solution containing a drying control chemical additive in the partial oxidation of propylene Original Research Article

The performance of Mo12Bi1.0Co4.4Fe1.0K0.07Ox mixed-metal oxide catalysts in the partial oxidation of propylene was investigated. Such catalysts were prepared by precipitating catalyst components from a sol–gel solution that contained a drying control chemical additive (DCCA). The addition of DCCA, selected from among glycerol, formamide and propionic acid, to a sol–gel solution did not change the crystallite phases of the prepared catalysts, which included MoO3, Bi2Mo3O12, Bi2MoO6, CoMoO4, Fe2O3, and α-FeMoO4, but did decrease the crystallite sizes, thereby increasing the catalytic activity. The DCCA-modified catalysts also exhibited selectivity values for the production of acrolein and acrylic acid that were higher than that of the catalyst prepared without using the additive. Among three DCCAs tested in this study, propionic acid added in a proper amount increased the selectivity to the greatest extent because propionic acid decreased the amounts of Brönsted-type acidic sites on the catalyst, which are detrimental to the selectivity.