Performance of the catalytic membrane reactors of different pore size with palladium as catalytic phase in hydrogenation and oxidation reactions

The catalytic membrane reactors (CMR) were prepared using commercial Hollow Fiber Membranes of corundum with 4 nm or 1400 nm pores and impregnated with palladium. The tests performed were phenol hydrogenation, hydrogen peroxide generation to oxidize phenol by advanced oxidation processes and chromium (VI) reduction. Reactions were performed in aqueous solution, at mild temperature and under atmospheric pressure. For all tests, the hydrogen passed through the membrane to be activated with palladium. The test with phenol showed that, in the absence of oxygen, the activated hydrogen reacts with the organic matter, leading to the formation of hydrogenated products; in the presence of oxygen, active hydrogen reacts with oxygen to form hydrogen peroxide and subsequently hydroxyl radicals that attack the organic matter until its mineralization. Furthermore, the CMR is capable of reducing chromium (VI) to chromium (III). The CMRs of smaller pore size presented better performance in all reactions.