Organic groups are grafted to 250-nm-diameter MCM41 nanoparticles with a spherical morphology to enhance the CO−water volumetric mass-transfer coefficient (kLa) for synthesis gas fermentation. The results indicate that (i) 250-nm MCM41 nanoparticles show a higherkLa value than large silica particles (1.4 and 7 μm), (ii) surface hydroxyl groups on MCM41 nanoparticles play an important role in mass-transfer enhancement, (iii) organic groups grafted to MCM41 modify the mass-transfer enhancement, and (iv) mercaptan groups grafted to MCM41 show the most mass-transfer enhancement of 1.9 times that of no nanoparticle addition. The CO−water mass-transfer enhancement depends on the interaction between the nanoparticles and the CO molecules, which is influenced by the hydrophobicity of the nanoparticles and the functional group on the nanoparticles.
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Reprinted with permission from Industrial & Chemistry Engineering Research 47 (2008): 7881–7887, doi:10.1021/ie800238w. Copyright 2008 American Chemical Society.