Abstract:

In order to observe and identify the intermediates and the change of the catalyst under reaction conditions, we have designed and assembled a high temperature and high pressure infrared spectrophotometer cell. The cell, constructed from stainless steel with NaCl or CaF₃ windows, can withstanb 100 atm, and 200℃ The measurement system consists of autoclave, circulating pump and spectrophotometer cell. The infrared spectra are recorded using a Microlab-600 infrared spectrophotometer. The temperature and pressure in the cell are the same as that in the autoclave, so that it can be used in "in situ" tracing the behaviour of liquid, gase and liguid-gas mixtures.For the hydroformylation reaction of proplene with rhodium-phosphine complex catalyst, the transition of catalyst precursor Rh(acac)(CO)(PPh₃) to active species RhH(CO)₂(PPh₃)₃ has been recorded under the industrial reaction conditions (t=100℃, p=17atm. butyl aldehyde as solvent). If the pressure of synthetic gas is rather low, only RhH(CO)(PPh₃)₃ can be identified. The active species RhH(CO)₂(PPh₃)₂ disappears while the catalyst loses its reactivity. The oxidation of the ligand PPh₃ and the formation of OPPh₃ have been characterized under the oxygen atmosphere. In this case, the deactivation of catalysts, the formation of catalyst dimer, oxidation of proplene to acetone and the dynamics of CO oxidation to form CO₃ have been traced.In this paper, the experimental method concerning the "in situ" infrared tracing technique, high temperature and high pressure I. R spectrophotometer cell have been described and some experimental data and results have been given.