•High selectivity toward n-butanol (67.6%) was achieved over Pd-CeO2/AC catalyst.•Metals with high capability of hydrogen activation and spillover have high n-butanol selectivity.•Performance of catalysts was depended on their de/hydrogenation and CC cracking capabilities.M-CeO2/AC (M = Cu, Fe, Co, Ni and Pd) catalysts were prepared and evaluated in the continuous catalytic upgrading of ethanol to n-butanol under mild reaction conditions. The highest selectivity to n-butanol (67.6%) was achieved over Pd-CeO2/AC catalyst, while Cu-CeO2/AC catalyst exhibited the highest ethanol conversion (46.2%) with moderate selectivity to n-butanol (41.3%). The catalytic performance of these catalysts was shown for the first time to largely depend on the dehydrogenation, hydrogenation and CC bond cracking capabilities of each individual supported metal.M-CeO2/AC (M = Cu, Fe, Co, Ni and Pd) catalysts were synthesized and compared in the continuous catalytic upgrading of ethanol to n-butanol under mild reaction conditions. The catalytic performance of catalysts was mainly depended on their dehydrogenation, hydrogenation and CC bond cracking capabilities.Download high-res image (133KB)Download full-size image

In this paper, the deactivation causes of the Pd/SiO2 catalyst for continuous liquid-phase selective hydrogenation of 6,10,14-trimethylpentadeca-13-en-2-one in 2000 h of pilot plant test were systematically investigated by N2 adsorption–desorption, thermogravimetric and differential thermal analyses, scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray fluorescence, experiments of CO poisoning and regeneration, and laboratory retests of the deactivated catalyst samples. The pore textures of Pd/SiO2 catalysts were not destructed during the pilot test, while there were no obvious carbonaceous deposits appearing on the deactivated catalyst samples. The sintering and crystallization of Pd metal nanoparticles were found, which could be partially accountable for the deactivation of Pd/SiO2 catalysts. Though Pd leaching did not take place in the pilot test, the Pd active phase could be slightly poisoned by sulfur impurities from feedstock hydrogen. Combining the results of CO poisoning and regeneration experiments with those of compositional analyses of fresh and circulating hydrogen in the pilot test, it could be concluded that CO poisoning should be another important reason for the deactivation of the Pd/SiO2 catalyst due to high concentration of CO in the reaction system of pilot test and relatively low reaction temperature in the middle and at the bottom of the catalyst bed. Fortunately, the CO poisoned Pd/SiO2 catalyst in the pilot test could be in situ regenerated by installing a purifier for CO elimination from the circulating hydrogen and increasing the temperature of the whole catalyst bed to slightly higher than 383 K.

•Up to 71.91% yield of diesel-like hydrocarbons (C17 + C18 products) can be achieved.•Solvents can generate in situ hydrogen for hydrogenation.•In situ hydrogen from solvents is more reactive than from aqueous phase reforming.An integrated catalytic transfer hydrogenation (CTH) and aqueous phase reforming (APR) process was applied for the hydrothermal hydrodeoxygenation of triglycerides to diesel-like hydrocarbons in the presence of water. Up to 71.91% yield of diesel-like hydrocarbons (C17 + C18 products) could be achieved when using decalin as solvent at 523 K with autogenous pressure after 12 h of reaction time. The promotional effect on the hydrodeoxygenation of triglycerides was ascribed to the high reactivity of in situ generated H2 from solvents.Hydrothermal hydrodeoxygenation of triglycerides with in situ generated hydrogen could give rise to 71.91% yield of diesel-like hydrocarbons (C17 + C18 products) at 523 K with autogenous pressure after 12 h of reaction time.Download high-res image (156KB)Download full-size image