Effect of dense CO2 on the removal of strongly adsorbed benzaldehyde from (VO)2P2O7 surfaces: a transmission FTIR study

The desorption/removal of chemisorbed benzaldehyde from vanadyl pyrophosphate (VO)2P2O7 surface in dense CO2 at a temperature of about Tfluid=313 K is reported. The desorption process was investigated by in situ transmission FTIR spectroscopy. It has been shown that under subcritical conditions (p(CO2)=56.6 bar) the adsorbed benzaldehyde remains to a large extent on the catalyst surface within 30 min, whereby under supercritical conditions (p(CO2)=90.6 bar) the aldehyde desorbs largely within a short time period (about 1 min) from the surface. In situ investigations in the range of 64–90 bar in dense CO2 (Tc=304 K, pc=73.8 bar) demonstrate that the desorption of benzaldehyde is directly proportional to the density of CO2 which indicates the enhanced solvent power of CO2 with increasing pressure at a reduced temperature of Tr=T/Tc=1.03.