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T-type microchannel reactors were used to prepare monodispersed nanocrystals of barium sulfate and boehmite. The size of barium sulfate is strongly dependent on the velocity of the reactants in the channel. High velocity is beneficial for producing small particles. The concentration of reactants also affects the size. Boehmite was prepared by neutralization of NaAlO2 and Al2(SO4)3. Changing the proportion of NaAlO2 and Al2(SO4)3 will lead to different pH values which determine the phase of alumina. High efficiency of micromixing is the key factor of the purity of the alumina morphology. Na2CO3 was used to adjust pH at given value during aging process. Aging is indispensable for the amorphous alumina to crystallize to boehmite. Raising the age temperature would reduce the time the crystallization need. The morphology and purity were characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM).

This study showed that a ZnO-Cr2O3/CeO2-ZrO2/Al2O3 (Zn-Cr) catalyst was a promising catalyst for hydrogen production from methanol due to its high stability and selectivity. There was no significant deactivation of the catalyst over 300 min of continuous operation when water was introduced into the feed. In the absence of water, the catalyst deactivated rapidly due to coke formation. The addition of water into the feed changed the route of methanol conversion and improved its rate. In order to investigate the pathway of CO formation. three reactions, i.e. decomposition of methanol (DM), steam reforming of methanol (SRM) and water gas-shift (WGS), were studied in this paper. The results showed that CO and CO2 were produced through the DM reaction and SRM reaction, respectively. The WGS and reverse WGS reactions were negligible. Adding H, and CO in the feed did not influence the process behavior of the SRM reaction. The addition of CO2 and H2O into the feed decreased the yield Of CO2. (c) 2006 Elsevier B.V. All rights reserved.

It is indispensable to remove CO at the level of less than 50 ppm in H2-rich feed gas for the proton exchange membrane (PEM) fuel cells. In this paper, catalyst with high activity and selectivity, and a microchannel reactor for CO preferential oxidation (PROX) have been developed. The results indicated that potassium on supported Rh metal catalysts had a promoting effect in the CO selective catalytic oxidation under H2-rich stream, and microchannel reactor has an excellent ability to use in on-board hydrogen generation system. CO conversion keeps at high levels even at a very high GHSV as 500 000 h −1 , so, miniaturization of hydrogen generation system can be achieved by using the microchannel reactor.