No abstract

Zeolite-supported metal nanocluster catalysts have attracted significant attention due to their broad application in heterogeneously catalyzed reactions. The preparation of highly dispersed metal catalysts commonly involves the use of organic compounds and requires the implementation of complicated procedures, which are neither green nor deployable at the large scale. Herein, we present a novel facile method (vacuum-heating) which employs a specific thermal vacuum processing protocol of catalysts to promote the decomposition of metal precursors. The removal of coordinated H 2 O via vacuum-heating restricts the formation of intermediates (metal-bound OH species), resulting in catalysts with a uniform, metal nanocluster distribution. The structure of the intermediate was determined by in situ Fourier transform infrared, temperatureprogrammed decomposition, and X-ray absorption spectroscopy (XAS) measurements. This alternative synthesis method is eco-friendly and costeffective as the procedure occurs in the absence of organic compounds. It can be widely used for the preparation of catalysts from different metal species (Ni, Fe, Cu, Co, Zn) and precursors and is readily scaled-up.

The in situ X-ray absorption fine structure (XAFS) was measured in the titanium-peroxo system supported by titanium silicalite-1 (TS-1). After this, the complex was heated, in line with previous in situ FTIR studies, in order to reproduce the catalytic conditions in those studies which demonstrate a reaction pathway to reaction products other than epoxides, namely, carbonyls, which have not been reported previously on this type of catalyst.

To address pressures associated with the increasing demand for the use of renewable liquid fuels, production of biodiesel has increased significantly resulting in a concomitant increase in glycerol production. A potential technology which has been examined in this study for utilising this potential waste product is to consider glycerol as well as its decomposition products, as fuels for use in a solid oxide fuel cell. Common glycerol derivatives, acrolein and allyl alcohol, have been examined as feeds, where it was found that allyl alcohol partially undergoes direct oxidation through interaction of the hydroxyl functional group, while the acrolein deactivates the anode through rapid carbon deposition. Additionally, it was shown that glycerol can be used as a fuel directly, with over 90 hours operation without cell deactivation, attributed to its’ highly oxygenated nature through multiple hydroxyl groups interacting with the catalytic anode, resulting in direct oxidation of the glycerol. It was also found that the introduction of salt contaminants typically found as a result of industrial biodiesel synthesis, such as NaCl, resulted in catalyst deactivation due to the formation of undesirable species, in this instance surface NiCl2.

Conversion of glycerol to allyl alcohol in a flow reactor and subsequent conversion to glycidol in a batch reactor are discussed in this paper. To increase reaction selectivity in the glycerol to allyl alcohol reaction, the catalyst was modified with alkali metal salts. The treatment of the catalyst (Fe/Al 2 O 3 ) with potassium, caesium and rubidium salts enhanced the allyl alcohol yield when a 35 wt% glycerol solution was used as feed. Furthermore, the addition of organic reductants or hydrogen to the glycerol feed increased the allyl alcohol yield. Optimisation of allyl alcohol selectivity was achieved by a combination of alkali metal cation modifiers and the addition of reductants. The influence of acid, base and redox properties on selectivity is presented, focusing on the effect of these properties on product distribution. The effect of by-products from the conversion of glycerol to allyl alcohol on the epoxidation reaction was examined to identify the ideal reaction conditions for maximising the glycidol yield. Epoxidation of allyl alcohol by 30 wt% hydrogen peroxide was conducted in a batch reactor at 333K using titanium silicate-1 catalyst. Conversion of allyl alcohol was high for all conditions; however, hydrolysis of glycidol to glycerol reduces selectivity.