Molybdenum/Bismuth Based Mixed Metal Oxide Catalysts for Selective Propylene Oxidation and Zeolite Membrane Protected Palladium/Alumina Catalysts for Selective Carbon Monoxide Oxidation and Application in a Process Loop Using a Propane Feed

Abstract

As part of a process loop to make acrylic acid from propane, catalysts for two reactions have been investigated. Mo/Bi based mixed metal oxides for selective oxidation of propylene in a propane feed have been prepared by a sol-gel method which increased activity over the standard catalyst. Modifications of the molecular formula led to an increase in selectivity towards acrolein whilst maintaining the improved conversion. X-ray diffraction (XRD) analysis showed the sol-gel method helped incorporate the various mixed metal oxides and prevented segregation during reaction conditions. A Pd-loaded 4A zeolite membrane catalyst was developed on the surface of 1 mm beads γ-Al2O3 support. The membrane was employed in the selective oxidation of CO in a propane-rich mixture. The zeolite coating was developed by using a new modification of the hydrothermal synthesis (dilution method). Catalytic test results confirmed that the selective oxidation of CO in the presence of propane is possible by using a 4A zeolite membrane coated on a Pd based catalyst. Temperature and time during zeolite preparation are key parameters in the stability and reproducibility of the zeolite membrane. The seeding method improves the growth of the zeolite on the catalyst surface and does not affect the stability and reproducibility of catalyst. By using this catalyst it is possible to get a temperature window for the selective oxidation of CO (65°C).