Hydrogenation of butanal over silica-supported Shvo's catalyst and its use for the gas-phase conversion of propene to butanol via tandem hydroformylation and hydrogenation

The objective of the present study was to develop a heterogeneous catalyst for the hydrogenation of butanal that could function in the presence of CO and propene and, hence, could be used in a tandem reactor to enable the gas-phase conversion of propene and synthesis gas to butanol. To this end, we investigated the activity of silica-supported Shvo's catalyst (Shvo/SiO2) for the gas-phase hydrogenation of butanal. Experiments were performed to determine the kinetics of n- and iso-butanal hydrogenation. The apparent activation energies and the apparent partial pressure dependencies of n- and iso-butanal, H-2, and CO on the rates of n- and iso-butanol formation were determined. A mechanism for butanal hydrogenation was proposed to rationalize the observed kinetics and some of the reaction intermediates were observed by in situ infrared and P-31 MAS NMR spectroscopy. It was found that Shvo/SiO2 was inhibited by SX (SX = sulfoxanthphos) and CO, and is inactive for alkene hydrogenation. The tandem catalytic conversion of propene and synthesis gas to butanol was then carried out using a SX-Rh supported ionic liquid phase (SILP) catalyst to promote the hydroformylation of propene to butanal and Shvo/SiO2 to promote the hydrogenation of butanal to butanol. The rate expressions describing the kinetics of each of the catalysts were then used to predict operating conditions required to achieve high conversion of propene to butanol. Under the most favorable conditions examined (H-2/CO = 10), an overall yield of 13% to butanol was achieved with 15% propene conversion and 90% aldehyde conversion at a temperature of 413 K. (C) 2013 Elsevier Inc. All rights reserved.