We report the direct production of 1,3-butadiene from the dehydration of 2,3-butandiol by using alumina as catalyst. Under optimized kinetic reaction conditions, the production of methyl ethyl ketone and isobutyraldehyde, formed via the pinacol–pinacolone rearrangement, was markedly reduced and almost 80 % selectivity to 1,3-butadiene and 1,3-butadiene could be achieved. The presence of water plays a critical role in the inhibition of oligomerization. The amphoteric nature of γ-Al₂O₃ was identified as important and this contributed to the improved catalytic selectivity when compared with other acidic catalysts.

The selective hydrogenation of furfuryl alcohol was investigated at room temperature by using supported palladium catalysts. The catalysts are very selective to the formation of 2-methylfuran. Furthermore, the addition of tin to palladium showed similar catalytic activity, but was more selective to tetrahydrofurfuryl alcohol. Variation of the Sn/Pd ratio has shown a considerable and interesting effect on the selectivity pattern. Addition of a small amount of Sn (1 wt %) shifted the selectivity towards tetrahydrofurfuryl alcohol and methyltetrahydrofuran, which are ring-saturated molecules. Increasing the tin ratio further decreased the catalytic activity and also showed very poor selectivity to either of these products.

The effect of ceria and zirconia grafting onto alumina (α and θ–δ phases) as supports for silicotungstic acid for the dehydration of glycerol to acrolein was studied. 30 % Silicotungstic acid (STA) supported on 5 % zirconia/δ,θ-alumina was the best catalyst, producing 85 % selectivity to acrolein at 100 % glycerol conversion, and it showed stable activity without using oxygen as a co-feed. The catalyst produced a STA of 90 g_(acrolein) kg_(cat)⁻¹ h⁻¹, which was greater than the STA simply supported on δ,θ-alumina, which only demonstrated 75 % selectivity towards acrolein. The effect of grafting on the support material was investigated by means of nitrogen adsorption, ammonia temperature-programmed desorption, thermogravimetric analysis, Raman spectroscopy, and powder X-ray diffraction. A pulsed-field gradient (PFG) NMR technique was also used to study diffusion processes associated with the catalysts. Diffusion studies of the grafted catalysts showed that zirconia contributes to the formation of more tortuous pathways within the pore structure, leading to the diminution of acid strength and making the catalyst less susceptible to coke formation.

MnO₂ was synthesised as a catalyst support material using a hydrothermal method. This involved reacting MnSO₄⋅H₂O and (NH₄)₂S₂O₈ at 120 °C for a range of crystallisation times, which affords control over the morphology and phase composition of the MnO₂ formed. Gold was deposited on these supports using sol-immobilisation, impregnation and deposition precipitation methods, and the resultant materials were used for the oxidation of benzyl alcohol and carbon monoxide. The effect of the support morphology on the dispersion of the gold nanoparticles and the consequent effect on the catalytic performance is described and discussed.

Base-free selective oxidation of glycerol has been investigated using trimetallic Au–Pd–Pt nanoparticles supported on titania and their corresponding bimetallic catalysts. Catalysts were prepared by the sol-immobilization method and characterized by means of TEM, UV/Vis spectroscopy, diffuse reflectance infrared fourier transform spectroscopy, X-ray photoelectron spectroscopy, and microwave plasma–atomic emission spectroscopy. It was found that of the bimetallic catalysts, Pd–Pt/TiO₂ was the most active with high selectivity to C₃ products. The addition of Au to this catalyst to form the trimetallic Au–Pd–Pt/TiO₂, resulted in an increase in activity relative to Pd–Pt/TiO₂. The turnover frequency increased from 210 h⁻¹ with the Pd–Pt/TiO₂ catalyst to378 h⁻¹ for the trimetallic Au–Pd–Pt/TiO₂ catalyst with retention of selectivity towards C₃ products.

The oxidation of 1,4-butanediol and butyrolactone have been investigated by using supported gold, palladium and gold–palladium nanoparticles. The products of such reactions are valuable chemical intermediates and, for example, can present a viable pathway for the sustainable production of polymers. If both gold and palladium were present, a significant synergistic effect on the selective formation of dimethyl succinate was observed. The support played a significant role in the reaction, with magnesium hydroxide leading to the highest yield of dimethyl succinate. Based on structural characterisation of the fresh and used catalysts, it was determined that small gold–palladium nanoalloys supported on a basic Mg(OH)₂ support provided the best catalysts for this reaction.

We report the solvent-free oxidation of 1-hexene with air by using supported gold catalysts with a catalytic amount of tert-butyl hydroperoxide (TBHP) as initiator. We confirm that gold supported on graphite is an effective catalyst for such oxidations and that graphite was the preferred support. Preparation of catalysts using modified sol-immobilisation was found to be effective, particularly when the PVA stabiliser was removed by a solvent treatment prior to the reaction.

The partial oxidation of methane to methanol presents one of the most challenging targets in catalysis. Although this is the focus of much research, until recently, approaches had proceeded at low catalytic rates (<10 h⁻¹), not resulted in a closed catalytic cycle, or were unable to produce methanol with a reasonable selectivity. Recent research has demonstrated, however, that a system composed of an iron- and copper-containing zeolite is able to catalytically convert methane to methanol with turnover frequencies (TOFs) of over 14 000 h⁻¹ by using H₂O₂ as terminal oxidant. However, the precise roles of the catalyst and the full mechanistic cycle remain unclear. We hereby report a systematic study of the kinetic parameters and mechanistic features of the process, and present a reaction network consisting of the activation of methane, the formation of an activated hydroperoxy species, and the by-production of hydroxyl radicals. The catalytic system in question results in a low-energy methane activation route, and allows selective C₁-oxidation to proceed under intrinsically mild reaction conditions.

The efficacy of using cerium oxide foams as a support for Au nanoparticles and subsequent use as oxidation catalysts have been investigated. These were synthesized using L-asparagine to produce a cerium coordination polymer foam, which was calcined to give the oxide foam. Au nanoparticles were supported on the CeO₂ foams using a sol-immobilization method. The activity of the Au/foamCeO₂ for solvent-free benzyl alcohol oxidation was superior to standard Au/CeO₂ catalysts, and the activity was found to be dependent on the crystallization time of the precursor foam. A crystallization time of 4 h was found to produce the most active catalyst, which retained activity and a high selectivity to benzaldehyde (ca. 96 %) when re-used and this is related to the structure of the material. The high activity is attributed to the greater lability of surface oxygen in the support compared with commercial CeO₂ materials.

In the solvent-free oxidation of benzyl alcohol to benzaldehyde using supported gold–palladium nanoparticles as catalysts, two pathways have been identified as the sources of the principal product, benzaldehyde. One is the direct catalytic oxidation of benzyl alcohol to benzaldehyde by O₂, whereas the second is the disproportionation of two molecules of benzyl alcohol to give equal amounts of benzaldehyde and toluene. Herein we report that by changing the metal oxide used to support the metal–nanoparticles catalyst from titania or niobium oxide to magnesium oxide or zinc oxide, it is possible to switch off the disproportionation reaction and thereby completely stop the toluene formation. It has been observed that the presence of O₂ increases the turnover number of this disproportionation reaction as compared to reactions in a helium atmosphere, implying that there are two catalytic pathways leading to toluene.

Vanadium phosphate materials, based on a VOHPO₄⋅0.5 H₂O precursor and with (VO)₂P₂O₇ as an active high-temperature phase, are used as catalysts for the oxidation of alkanes. VOHPO₄⋅0.5 H₂O is prepared from VOPO₄⋅2 H₂O using 1-octanol, 3-octanol, 2-butanol, or 2-methyl-1-propanol as both solvent and reducing agent. With 1-octanol, the reaction temperature was found to be crucial in obtaining a high yield of the precursor phase. At temperatures of 160 °C or greater, a solution containing V⁴⁺ ions formed in preference to VOHPO₄⋅0.5 H₂O. However, VOHPO₄⋅0.5 H₂O formation can be achieved above 160 °C by carrying out the reduction process in the presence of a small amount of vanadium phosphate material, which effectively acts as a templating seed. The use of this seeding concept is shown to have a dramatic effect on the morphology of the final activated catalyst. In contrast, when 3-octanol is used, solely VO(H₂PO₄)₂ is generated, except in the presence of a vanadium phosphate seed where significant amounts of VOHPO₄⋅0.5 H₂O can also be formed. Furthermore, VO(H₂PO₄)₂ can be transformed to VOHPO₄⋅0.5 H₂O by heating at reflux with an alcohol in the presence of VOHPO₄⋅0.5 H₂O precursor seeds. The findings reported herein show that both the phase composition and morphology of vanadium phosphates can be influenced by the use of seeds during the preparation process.

The effect of pretreating Au–Pd catalysts on MgO and C supports with aqueous bromide solution, prior to using them for the direct synthesis of hydrogen peroxide, has been investigated. These two supports were selected since the parent materials exhibit contrasting microstructures and activities. The carbon-supported catalysts comprise homogeneous Au–Pd alloy nanoparticles, which give high activity, whereas the MgO-supported catalyst has Au–Pd alloys with a Pd-rich surface and a Au-rich core, which result in lower activity. Pretreatment of these catalysts with bromide was found to enhance H₂O₂ productivity and the degree of enhancement was largely dependent on the nature of the Au–Pd nanoparticles. Whereas bromide pretreatment significantly enhanced H₂O₂ productivity over the MgO-based catalysts, the carbon-based catalyst only showed a subtle promotional effect. Very low loadings of bromide (0.00034–0.044 wt %) were required to yield a significant positive effect. Higher bromide loadings (0.5–8.3 wt %) proved deleterious. The promotional effect has been correlated to selective poisoning of sites responsible for H₂O₂ hydrogenation and decomposition. In view of the limited effect of bromide pretreatment on the yield of H₂O₂ coupled with the effective performance of the carbon supported Au-Pd catalysts in the absence of halides, for practical processes the addition of halides is not considered advisable with this catalyst system.

Glycolic acid is an important chemical that has uses as a cleaning agent as well as a chemical intermediate. At present glycolic acid is manufactured from either chloroacetic acid or from formaldehyde hydrocyanation, both routes being nongreen and using nonsustainable resources. We investigate the possibility of producing glycolate from the oxidation of glycerol, a sustainable raw material. We show that by using 1 % wt Au/carbon catalysts prepared using a sol-immobilization method glycolate yields of ca. 60 % can be achieved, using hydrogen peroxide as oxidant in an autoclave reactor. We describe and discuss the reaction mechanism and consider the reaction conditions that maximize the formation of glycolate.