Compensation effect in trichlorosilane synthesis

In a recent publication [J. Acker, K. Bohmhammel, J. Phys. Chem. B 106 (2002) 5105], the reactions between transition metal silicides and hydrogen chloride were studied by isothermal calorimetric measurements. The obtained apparent activation energies and pre-exponential factors show clearly a linear dependence that is attributed to the compensation effect. An isokinetic temperature of 696.9±22.1 K was determined. According to Larssonʹs model of selective energy transfer, a characteristic frequency of 969.3±46.5 cm−1 is calculated. The occurrence of the compensation effect is discussed in terms of chemisorption, precursor formation, and the involvement of surface species in essential reaction steps.