Polymerization of gaseous benzyl alcohol. 2. Kinetic study of the polymerization and of the deactivation for a silica/alumina catalyst

Abstract

As a method for lower temperature disposal of potentially hazardous waste, nuclear-grade ion-exchange resin was thermally decomposed at 450 °C, and the decomposition products were passed through catalyst-impregnated monolith reactors under oxidizing conditions. Among the four catalysts tested, alumina-supported 0.1% Pt-Pd and 10% V205 were found to be the most active for oxidation

Polymerization of gaseous benzyl alcohol. 3. Deactivation mechanism of silica/alumina catalyst

“…In the first part of this work (Olazar et al, 1987a), the properties of the obtained polymers, the effect of the reaction conditions, and the behavior of the different Si02-Al203 catalysts were studied. In the kinetic study carried out in the second part of this work (Bilbao et al, 1987a), it was proven that the polymerization before the deactivation of the catalyst is noticeable, that it followed a Langmuir-Hinshelwood-type mechanism, and that the corresponding kinetic equation fit the experimental data in the whole range of operating conditions (monomer concentration and temperature) possible in the laboratory.…”

“…The kinetic study of the deactivation is complex, due to the difficulties of the necessary experimentation as well as to the lack of existence of a method for data analysis for this type of reaction. In a first approach and in an empirical way, the activity vs time data were fit at a polymerization temperature of 270 °C to a first-order kinetic equation with respect to activity and to the partial pressure of benzyl alcohol (Bilbao et al, 1987a). Nevertheless, this equation, apart from not being based on any mechanism and not taking into account the intervention of the catalyst and of the reaction components through the deactivation, do not properly fit the experimental data for the whole range of working temperatures and of monomer concentrations.…”

Design and operation of a jet spouted bed reactor with continuous catalyst feed in the benzyl alcohol polymerization

“…Kinetic equations determined in previous work will be used (Bilbao et al, 1987) in the design. To consider the effect of time on the polymer deposition, it must be taken into account that this deposition goes through the periods outlined in Figure 4.…”

“…In previous works (Olazar, 1985;Olazar et al, 1987; Bilbao et al, 1987), benzyl alcohol polymerization in the gas phase, via dehydration, on acidic solid catalysts was studied. Running this reaction has two problems: the reaction is very exothermic and polymer is deposited outwardly on the catalyst particles, which consequently grow in the course of the reaction.…”

“…The polymerization kinetic study (Bilbao et al, 1987) was carried out in a fluidized bed reactor of constant section of 16-mm inside diameter, which was discontinuous for the catalyst. When we tried to operate this reactor in a continuous circulating regime for the catalyst, we could not maintain the bed well fludized; that is to say, it was impossible to keep the solid well mixed after 10-20 min, depending on the reaction conditions.…”