The selective hydrogenation of α,β‐unsaturated aldehydes and ketones has been studied using ketoisophorone and cinnamaldehyde as model substrates using manganese oxide octahedral molecular sieve (OMS‐2) based catalysts. For the first time, OMS‐2 has been shown to be an efficient and selective hydrogenation catalyst. High selectivities for either the CC or CO double bond at ≈100 % conversion were achieved by using OMS‐2 and platinum supported on OMS‐2 catalysts. Density functional theory (DFT) calculations showed that the dissociation of H2 on OMS‐2 was water assisted and occurred on the surface Mn of OMS‐2(0 0 1) that had been modified by an adsorbed H2O molecule. The theoretically calculated activation barrier was in good agreement with the experimentally determined value for the hydrogenation reactions, indicating that H2 dissociation on OMS‐2 is likely to be the rate‐determining step. A significant increase in the rate of reaction was observed in the presence of Pt as a result of the enhancement of H2 dissociative adsorption and subsequent reaction on the Pt or spillover of the hydrogen to the OMS‐2 support. The relative adsorption strengths of ketoisophorone and cinnamaldehyde on the OMS‐2 support compared with the Pt were found to determine the product selectivity.

Soot samples as potential mimics of atmospheric aerosols have been produced from the combustion of toluene, kerosene and diesel in order to compare the nature of soot produced from a simpler material, toluene, with soots from the fuels kerosene and diesel. Characterisation of the soots using elemental analysis, infrared spectroscopy, solvent extraction, thermal desorption and electron microscopy techniques before and after reaction with ozone allows assessment of the reactivity of soots from these different fuels. Despite the production of toluene and kerosene soots from identical combustion conditions, strong differences in structure and reactivity are observed in terms of their reaction with ozone. However, toluene soot is a much better mimic of diesel soot. It is proposed that the differing reactivities of the soots is related to the nature of the organic carbon and structure of the elemental carbon which vary with soots from the different fuels.

DRIFTS, TGA and resistance measurements have been used to study the mechanism of water and hydrogen interaction accompanied by a resistance change (sensor signal) of blank and Pd doped SnO(2). It was found that a highly hydroxylated surface of blank SnO(2) reacts with gases through bridging hydroxyl groups, whereas the Pd doped materials interact with hydrogen and water through bridging oxygen. In the case of blank SnO(2) the sensor signal maximum towards H(2) in dry air (R(0)/R(g)) is observed at approximately 345 degrees C, and towards water, at approximately 180 degrees C, which results in high selectivity to hydrogen in the presence of water vapors (minor humidity effect). In contrast, on doping with Pd the response to hydrogen in dry air and to water occurred in the same temperature region (ca. 140 degrees C) leading to low selectivity with a high effect of humidity. An increase in water concentration in the gas phase changes the hydrogen interaction mechanism of Pd doped materials, while that of blank SnO(2) is unchanged. The interaction of hydrogen with the catalyst doped SnO(2) occurs predominantly through hydroxyl groups when the volumetric concentration of water in the gas phase is higher than that of H(2) by a factor of 1000.

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Diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) has been employed along with chemical and isotope transients to study the catalytic CO hydrogenation over Co/MgO catalysts in a single fixed-bed reactor at T = 523 K and ambient pressure conditions (H2/CO = 3). According to the operando DRIFTS measurements, the catalyst surface contains hydroxyl groups, adsorbed CO, formate, and methylene groups in the steady-state of the reaction. Transient experiments following fast changes in the feed (chemical transient kinetics, CTK) or isotope composition (steady-state isotopic transient kinetic analysis, SSITKA) have been carried out during DRIFTS and demonstrate that the formate/methylene “seen by DRIFTS” plays no role as imminent intermediates of the ambient pressure Fischer−Tropsch (FT) reaction. The SSITKA experiments (replacing 12CO by 13CO) show that the exchange rate of formate/methylene is significantly lower than that of ethane, which is one of the main reaction products of CO hydrogenation (followed by mass spectrometry). Formate is most probably bound as bidentate μ2-species to MgO or at the Co/MgO interface, while methylene stands for skeleton CH2 in either hydrocarbon or carboxylate.