Experimental investigation of ethylene hydroformylation to propanal on Rh and Co based catalysts

• Intrinsic C2H4 hydroformylation kinetics were measured in a high-throughput setup.
• The performance of Rh, Co and RhCo catalysts were compared.
• Temperature, pressure and inlet composition effects were investigated.
• Hydrogenation activation energy exceeds that of hydroformylation rate.
• CO is the most abundant surface intermediate.

Intrinsic hydroformylation kinetics have been measured in a high-throughput kinetic test setup at temperatures varying from 448 to 498 K, with the total pressure ranging from 1 to 3 MPa. A gaseous feed containing CO, C2H4 and H2 was used with space times varying from 2.7 kgcat s/molC2H4,in2.7 kgcat s/molC2H4,in to 149 kgcat s/molC2H4,in149 kgcat s/molC2H4,in. Three catalysts have been investigated, i.e., 5%Rh on Al2O3, 1%Co on Al2O3 and 0.5%Co–0.5%Rh on Al2O3. The main products observed were ethane, propanal and propanol. The Rh catalyst showed the highest hydroformylation and hydrogenation site time conversions in the investigated range of operating conditions. Moreover it was found on all investigated catalysts that the hydrogenation activation energy was about 15–20 kJ mol−1 higher than that for hydroformylation. On the Rh catalyst, higher ethylene feed concentrations have a more pronounced effect on CO conversion and production of propanal and propanol compared with an increase in the inlet concentration of the other reactants.

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