a b s t r a c tThe liquid-phase hydroalkylation of m-cresol catalyzed by zeolite catalysts doped with noble metals was investigated at 473 K and 5200 kPa of H 2 . Metals (Pt and Pd) were incorporated in HY (Si/Al = 30) and HMor (Si/Al = 10) zeolites by incipient wetness impregnation. The structural properties of the samples were characterized by NMR, XPS, and BET. Hydroalkylation of m-cresol involves a series of steps that start with the ring saturation to 3-methylcyclohexanone (MCONE), which is the primary product and is further hydrogenated to methylcyclohexanol (MCNOL) on the metal function. This, in turn, is dehydrated on the acid sites to 3-methylcyclohexene, which readily alkylates the unreacted m-cresol to form bicyclic compounds that fall in the desirable fuel range. In these bifunctional catalysts, differences in intrinsic hydrogenation activity of metals play an important role in determining the final selectivity to alkylated products. In fact, the ratio of number of acid sites (n A ) to exposed metal sites (n M ) can be tuned to maximize the selectivity toward bicyclic compounds because this selectivity is determined by the fate of the intermediate 3-methylcyclohexene (MCENE). That is, if the C@C hydrogenation on the metal is fast compared to alkylation on the acid site, the selectivity decreases. However, if the hydrogenation is too slow, the overall product yield decreases. Thus, to optimize the hydroalkylation yield, a delicate metal/acid balance is required. Moreover, in the absence of metal, the zeolite would deactivate very quickly. Therefore, having the metal and acid functions together is also important for extending the catalyst life. Finally, it has been observed that 3D-pore zeolites, such as HY, are preferred over 1D-pore zeolites such as HMor, which sharply diminish the formation of alkylation compounds, despite being more acidic than HY.

We report that when the Fischer−Tropsch synthesis (FTS) catalyzed by Ru particles supported on multiwall carbon nanotubes (Ru/CNT) is conducted in a biphasic decalin/water solvent mixture, the observed rate is significantly higher than in single-phase organic or aqueous medium. Multiwall carbon nanotubes of varying wettability and doped with Ru nanoparticles were tested as catalysts and stabilizers of biphasic emulsions in a batch reactor under FTS reaction conditions (H 2 :CO = 4:1, 220 °C, 55 bar). First, in comparison to the runs conducted in pure organic solvent, both rate and selectivity increased with the addition of a second (aqueous) phase. Likewise, a large increase in reaction rate was found when a second (organic) phase was incorporated, relative to that measured in pure aqueous phase. Notably, this rate increase was more substantial when the nanotubes employed were more hydrophobic and exhibited higher oil wettability. At the same time, for a given (Ru/CNT) catalyst, the rate increased with the oil/water solvent ratio, suggesting that not only the promotion by water but also the interaction of the catalyst surface with the organic solvents at the oil/water interfaces plays a key role in enabling higher rates. Because the rate changes are not due to changes in rates of mass transfer, it is concluded that the intrinsic kinetics was enhanced. Among the possible explanations for the enhanced kinetics, we discuss here some concepts recently proposed in the literature, including the waterpromotion of H-assisted CO dissociation and the disruption of dense CO surface layers by the organic solvent.

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