STUDIES ON THE CATALYTIC HYDROLYSIS OF BENZAMIDE BY Bi–Mo–O CATALYSTS

The catalytic hydrolysis of benzamide over mixed oxides Bi2O3-MoO3 , Bi2O3-2MoO3 and Bi2O3 - 3MoO3 , was carried out at initial concentrations of benzamide (0.03 and 0.07M), using variable amounts of catalyst 0.25, 0.50 and l.0 gm/200 ml solution. The kinetic study was carried out at (25,35 and 45C°) and the effect of calcination time (30, 60, 90 and 120hr) was investigated, Such study revealed that the reaction is kinetically of first order type, and that the percent conversion increased with reaction temperature, quantity of catalyst, and also with increasing the ratio of MoO3 present in the catalyst, with the calcinations time .
In all steps of study the reaction rate is characterized by the presence of an induction period, in which the reaction velocity is slow, after which it is accelerated appreciably, is proposed that this period is sequence of the formation of some active sites on the surface of the catalyst. These active sites resemble themselves as ions (Mo+5 ) resulting form side reaction between (Bi+3) ions and (Mo+6) ions according to the following equation :
Mo+6 + Bi+3 Mo+5 + Bi+3 + e
where the increase in formed (Mo+5) ions leads to the increase of the active sites, and consequently an increase in the reaction velocity. The activity in the catalytic hydrolysis of benzamide found to follow the following sequence of the prepared catalysts: Bi2O3 - MoO3 < Bi2O3 - 2MoO3 < Bi2O3 - 3MoO3 < Bi2O3 - 3MoO3 (30hrs) < Bi2O3 - 3MoO3 (60hrs) < Bi2O3 - 3MoO3 (90hrs) < Bi2O3 - 3MoO3 (120hrs).