Continuous flow aerobic oxidation of benzyl alcohol on Ru/Al2O3 catalyst in a flat membrane microchannel reactor: An experimental and modelling study

Abstract

A flat Teflon AF-2400 membrane microchannel reactor was experimentally and theoretically investigated for aerobic oxidation of benzyl alcohol on a 5 wt% Ru/Al 2 O 3 catalyst. The reactor consisted of gas and liquid channels (75 mm (L) × 3 mm (W) × 1 mm (D)), separated by a 0.07 mm thick semipermeable Teflon AF-2400 flat membrane, which allowed continuous supply of oxygen during the reaction and simultaneously avoided direct mixing of gaseous oxygen with organic reactants. A catalyst stability test was first carried out, and the experimental data obtained were used to estimate the kinetics of benzyl alcohol oxidation with a 2D reactor model. Using these kinetics, predictions from the 2D reactor model agreed well with the experimental data obtained at different liquid flow rates and oxygen pressures. The mass transfer and catalytic reaction in the membrane microchannel reactor were then theoretically studied by changing the membrane thickness, the liquid channel depth, and the reaction rate coefficient. Oxygen transverse mass transport in the catalyst bed was found to be the controlling process for the system investigated, and decreasing the liquid channel depth is suggested to improve the oxygen supply and enhance the benzyl alcohol conversion in the membrane reactor.

Decomposition of Additive-Free Formic Acid Using a Pd/C Catalyst in Flow: Experimental and CFD Modelling Studies

“…Microreactors have been utilised for renewable fuel production due to various advantages such as enhanced mass transfer, better temperature control leading to improved heat transfer and larger surface area-to-volume ratios [23][24][25][26]. The collective advantages of microreactors allow the process to be greener and more environmentally sustainable.…”

Hydrogenation of carbon dioxide (CO2) to fuels in microreactors: a review of set-ups and value-added chemicals production

“…18 Great efforts have recently been accomplished to prepare microreactors with the aim of producing chemical fuels through CO 2 hydrogenation. 19 Microreactors such as continuous flow microreactors, 20,21 micro packed-bed reactors, 22,23 membrane, 24,25 and microplasma reactors can be used to enhance various unit operations and reactions in micro space. Moreover, microreactors exhibit pivotal advancements in chemical engineering, leading to excellent output yield of chemical fuels.…”

3D printed catalytic reactors for aerobic selective oxidation of benzyl alcohol into benzaldehyde in continuous multiphase flow

“…To evaluate the efficiency of the new catalyst design, benzyl alcohol oxidation to benzaldehyde was used as a model reaction [8][9][10] ; a well-referenced reaction for iron, cobalt and palladium-based catalysts [8][9][10][11][12][13][14][15][16] . Significant advances have been made in applying various metals and supports to the selective oxidation of benzyl alcohol, mostly in batch systems and less commonly in lab-scale flow reactor systems 17,18 . This involves the use of metal promoters such as ruthenium [18][19][20] , platinum 17,21 , rhodium 22 , copper 23 , chromium 24 , bimetallic gold-palladium and gold catalyst 15,[21][22][23][24] .…”

“…Significant advances have been made in applying various metals and supports to the selective oxidation of benzyl alcohol, mostly in batch systems and less commonly in lab-scale flow reactor systems 17,18 . This involves the use of metal promoters such as ruthenium [18][19][20] , platinum 17,21 , rhodium 22 , copper 23 , chromium 24 , bimetallic gold-palladium and gold catalyst 15,[21][22][23][24] . Furthermore, in order to develop a process with greener credentials, we used molecular oxygen in combination with an aqueous solvent 11,[25][26][27] .…”