A numerical study is performed in order to evaluate the performance and optimal operating conditions of a palladium membrane reactor for methanol synthesis. A novel reactor configuration with a Pd wall, which is perm-selective to hydrogen, has been proposed. In this configuration the reactants are added to the tube side while pure hydrogen is added to the shell side, as a result, the hydrogen diffuses across the membrane from the shell side to the tube side. In this membrane reactor, hydrogen penetrates to the reaction side in order to maintain a suitable hydrogen level in the whole length of the reactor and shift the equilibrium reaction. The effects of different parameters on the methanol output mole fraction were investigated in the cocurrent mode. These parameters were membrane thickness, reaction side flow rate, reaction side pressure, shell side pressure and H 2 =CO 2 ratio in the feed.

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This paper describes the measurement of induction time in the reaction crystallization of silver nanoparticles at different temperatures and supersaturations, and compares it with classical nucleation theory. Silver nanoparticles are synthesized by a reaction of silver nitrate with hydrazine in the presence of sodium citrate as stabilizer. Induction time is estimated from an absorption-time graph obtained by monitoring the absorption of the solution after creation of supersaturation. The results show that induction time decreases with increasing supersaturation and temperature. The classical nucleation theory can well predict experimental data. Interfacial tension is estimated at different temperatures and compared with two correlations for calculation of interfacial tension.