Performance of the Catalytic Membrane Reactors of Different Pore Size With Palladium as Catalytic Phase in Hydrogenation and Oxidation Reactions

Abstract

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.

Emerging Contaminants in Trans-American Waters

“…Research indicates that only a small amount of the ECs studied were efficiently eliminated after tertiary treatments of ultrafiltration, reverse osmosis and UV disinfection (Teijon et al, 2010). Advanced oxidation processes are an alternative, but have the disadvantage that they are specific for certain compounds, expensive and in many cases difficult to implement and may generate more toxic and recalcitrant compounds than the original ones (Pinos-Vélez et al, 2018).…”

Catalytic Palladium-Based and Iron-Based Membrane Reactors: Novel Strategies of Synthesis

“…On this basis, CMRs have been extensively used in numerous reactions, such as the production of H 2 O 2 from H 2 and O 2 ,− or from H 2 and airborne oxygen under very mild conditions, nitrate ion reduction using H 2 generated in situ from formic acid and hydrogenation, ,− or oxidation of different organic compounds. ,− The CMR technology presents a huge potential for different applications as it reduces the investment costs, increases the energy efficiency, and can be employed for a wide range of conditions with the aim of increasing the conversion in equilibrium limited reactions . Although there is a growing interest in the membrane reactor technology, the attention is focused more on the catalytic applications and less on the preparative methods.…”