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Recent advances with Pd containing catalysts for the selective hydrogenation of acetylene are described. The overview classifies enhancement of catalytic properties for monometallic and bimetallic Pd catalysts. Activity/ selectivity of Pd catalysts can be modified by controlling particle shape/morphology or immobilisation on a support which interacts strongly with Pd particles. In both cases enhanced ethylene selectivity is generally associated with modifying ethylene adsorption strength and/or changes to hydride formation. Inorganic and organic selectivity modifiers (i.e., species adsorbed onto Pd particle surface) have also been shown to enhance ethylene selectivity. Inorganic modifiers such as TiO 2 change Pd ensemble size and modify ethylene adsorption strength whereas organic modifiers such as diphenylsulfide are thought to create a surface template effect which favours acetylene adsorption with respect to ethylene. A number of metals and synthetic approaches have been explored to prepare Pd bimetallic catalysts. Examples where enhanced selectivity is observed are generally associated with decreased Pd ensemble size and/or hindering of the ease with which an unselective hydride phase is formed for Pd. A final class of bimetallic catalysts are discussed where Pd is not thought to be the primary reaction site but merely acts as a site where hydrogen dissociation and spillover occurs onto a second metal (Cu or Au) where the reaction takes place more selectively.

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Site data from 291 forest inventory plots in Mixed Dipterocarp Forest in centralSarawak were simplified by factor analysis. The distribution of the 33 commonest canopy tree species was related to site factor scores by 't' tests. There appears to be a degree of edaphic influence on the distribution of many species. Fairly constant soil characteristics related to the lithology of the parent material appear to be more important than ephemerally variable properties such as organic matter or exchangeable cations. Magnesium appears to be particularly important, possibly because of an effect on the capacity of mycorrhizal root systems to absorb phosphorus.

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The interactions between a Cu-based metal−organic framework (MOF), Cu-BTC, and an ionic liquid (IL), 1-ethyl-3methylimidazolium ethyl sulfate, were studied by employing density functional theory (DFT) calculations and vibrational spectroscopy. The Fourier transform infrared (FTIR) and Raman spectra show that the confinement of the IL in the MOF has significant impact on the structure of the MOF as well as on the IL. Raman spectra and DFT calculations reveal a perturbation of the symmetry of the MOF structure due to the interaction of the IL anion with the Cu ions. FTIR and Raman spectra show that the molecular interactions in turn influence the structure of the ion pair. Inside the MOF, two different types of structure of IL ion pairs are formed. One ion-pair structure exhibits enhanced interionic interactions by strengthening the hydrogen bonding between cation and anion, whereas the other structure corresponds to weaker interactions between the IL cation and anion. Moreover, it is shown that the IL imidazolium ring can directly interact with either the MOF or the anion. The difference electron density analysis by DFT calculations indicates that molecular interactions of MOF and IL are accompanied by a transfer and redistribution of electron density.

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Model CuO/Ce 0.8 X 0.2 O δ catalysts (with X = Ce, Zr, La, Pr, or Nd) have been prepared in order to obtain CuO/ceria materials with different chemical features and have been characterized by X-ray diffraction, Raman spectroscopy, N 2 adsorption, and H 2 temperature-programmed reduction. CO-PROX experiments have been performed in a fixed-bed reactor and in an operando DRIFTS cell coupled to a mass spectrometer. The CO oxidation rate over CuO/ceria catalysts correlates with the formation of the Cu + −CO carbonyl above a critical temperature (90 °C for the experimental conditions in this study) because copper−carbonyl formation is the rate-limiting step. Above this temperature, CO oxidation capacity depends on the redox properties of the catalyst. However, decomposition of adsorbed intermediates is the slowest step below this threshold temperature. The hydroxyl groups on the catalyst surface play a key role in determining the nature of the carbon-based intermediates formed upon CO chemisorption and oxidation. Hydroxyls favor the formation of bicarbonates with respect to carbonates, and catalysts forming more bicarbonates produce faster CO oxidation rates than those which favor carbonates.