Saleh Rawadieh

Catalyst-Adsorbent Configurations in Enhancing Adsorptive Reactor Performance

Fixed-bed columns containing solid catalysts and adsorbents were employed for simultaneous reaction and separation. The models developed for propene metathesis were validated with experimental data for configurations with and without the effect of pressure swing reaction. The models for the mass and momentum transfer in the catalyst bed and adsorber were solved using orthogonal collocation within the method of lines. The reactor/separator performances were tested for beds with varying numbers of layers of catalysts and adsorbents which were arranged sequentially. The pressure reaction columns behaved as reactor/separators in series. As the number of layers increased, a homogeneous distribution of the catalyst and adsorbent was approached in the limit. These configurations with variable catalyst/adsorbent distributions were investigated for propene metathesis reaction, in terms of product purity, selectivity, conversion, recovery, yield and productivity. Improved reactor performance was observed with a pressure swing separation system and in particular with close to well-mixed reactor/separator configurations.

The influence of intermediate radical termination and fragmentation on controlled polymer synthesis via RAFT polymerization

Reversible addition-fragmentation chain transfer (RAFT) polymerization allows the design of tailored polymers by inducing addition and fragmentation reactions via a powerful kinetic mechanism; the process, however, is not well understood. A parametric analysis was conducted in conjunction with experimental data to provide insights into the RAFT mechanism, accounting for the key kinetics events in RAFT polymerization of styrene. The effects of overall, forward and backward fragmentations of intermediate radicals were analysed with experimental data and sensitivity investigations. Our results show that the intermediate radicals undergo relatively fast fragmentation and that the radical cleavage is symmetrical. These factors, critical in design and control, were found to profoundly influence the process kinetics and the final polymer product attributes.

Optimizing packing heterogeneity for sorption enhanced metathesis reaction

An equilibrium-limited heterogeneous catalytic reaction, propene metathesis is suitable for process intensification via sorption enhanced reaction. In this work, we investigate the effect of catalyst/adsorbent configuration for propene metathesis in conjunction with pressure swing reaction. The catalyst and adsorbent configuration variations were defined in terms of packing heterogeneity index (PHI) and their effects were investigated experimentally and theoretically. Model predictions were tested against experimental data with variable PHI and adsorption/reaction conditions, including the absence of heterogeneity and of separation process. The product 2-butene was strongly adsorbed and retained by the intermediate adsorbent layers, thereby increasing reactant concentration in the reaction zone and enhancing conversion and rate of reaction in the subsequent layer. Model predictions were found to agree reasonably with experimental data and were used to elucidate the mechanism and optimizing principle for such reactors.