By using cetyltrimethylammonium bromide (CTAB) as the template, a series of mesoporous niobium phosphates were synthesized at different pH values in an aqueous solution. Techniques such as small-angle X-ray diffraction, transmission electron microscopy (TEM) and N 2 sorption technique were employed to characterize the mesoporous structures of thus-synthesized materials, EDAX to detect the composition, FTIR and solid state 31 P MAS NMR to investigate the framework information, while their acidic properties were analyzed using NH 3 -TPD and pyridine-FTIR. Samples prepared at neutral to acidic conditions exhibited high surface area (213-297 m 2 g À1 ), narrow pore size distribution (3-4 nm) and a great number of strong Lewis and Bro¨nsted acid sites. These materials exhibited excellent activity in the dehydration of fructose to 5-hydroxymethylfurfural (HMF) in water. The maximum HMF yield reached 45% under 130 1C with a reaction time of 0.5 h and the yield slightly decreased to 32% after five cycles and the five-cycled catalyst can be almost regenerated by calcination at 500 1C with the yield of 40%. The excellent catalytic activity obtained in the aqueous phase can be attributed to its high acid site density and the tolerance to water.
A one-pot method for the selective production of high-grade diesel-range alkanes from biomass-derived furfural and 2-methylfuran (2-MF) was developed by combining the hydroxyalkylation/alkylation (HAA) condensation of furfural with 2-MF and the subsequent hydrodeoxygenation (HDO) over a multifunctional Pd/NbOPO catalyst. The effects of various reaction conditions as well as a variety of solid-acid catalysts and metal-loaded NbOPO catalysts were systematically investigated to optimize the reaction conditions for both reactions. Under the optimal reaction conditions up to 89.1 % total yield of diesel-range alkanes was obtained from furfural and 2-MF by this one-pot method.
An energy-efficient catalytic system for the one-pot production of 1-octanol from biomass-derived furfural-acetone (FFA) under mild conditions in water was developed, by sequential hydrogenation/hydrogenolysis over a hydrophilic Pd/NbOPO 4 catalyst. A strategy of creating an intentional "phase problem" has been employed to prevent the over-hydrogenolysis of 1-octanol into n-octane and therefore increased the selectivity to 1-octanol. The effects of reaction conditions as well as a variety of noble-metal loaded bifunctional catalysts have been systematically investigated to maximize the yield of 1-octanol. Moreover, the addition of liquid acids to the catalytic system further enhanced the selectivity towards the formation of 1-octanol. There is a strong correlation between the acid strength of an acidic additive and the sum yield of 1-octanol and octane. With the addition of TfOH, the highest yield of 1-octanol (62.7%) was obtained from one-pot conversion of biomass-derived FFA over Pd/NbOPO 4 . † Electronic supplementary information (ESI) available. See
The conversion of xylose to furfural normally involves two steps: the isomerization of xylose to xylulose catalyzed by an enzyme, a base or a Lewis acid, followed by the acid-catalyzed dehydration of xylulose to furfural. To allow a more efficient single-step conversion, a new water-tolerant solid acid catalyst, mesoporous niobium phosphate was synthesized. This synthesis was performed using a soft template approach, with cetyltriethylammonium bromide (CTAB) as the template. The structure and properties of the catalyst thus synthesized were investigated by X-ray diffraction (XRD), N2 sorption, transmission electron microscopy (TEM), temperature-programmed desorption of NH3 (NH3-TPD), and pyridine sorption FTIR (Py-FTIR). These studies determined that the niobium phosphate not only had a large surface area (>200 m 2 •g-1) and narrow pore size distribution (3.5 nm), but also had relatively strong Lewis and Bro / nsted acidity. This catalyst was found to be capable of producing furfural via a simple one-pot process, including the isomerization of xylose to xylulose and subsequent dehydration. The influence of several variables including temperature, mass ratio of xylose/catalyst, and reaction time on the extent of xylose conversion and furfural yield were studied. Under optimal conditions, the yield of furfural in aqueous solution reached 49.8% with 96.5% xylose conversion. It was further determined that both the yield and the 2349
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