In recent years, metal−metal oxide catalysts have proven to be robust catalysts for hydrodeoxygenation (HDO) of oxygenated compounds derived from biorenewable feedstocks to value-added products. Herein, the conversion of 1,2,6-hexanetriol (1,2,6-HT) to 1,6-hexanediol (1,6-HD) in aqueous media over a Pt-WO x /TiO 2 catalyst is examined via isotope incorporation in HDO of a model compound, 1,2-pentanediol (1,2-PD). Absence of a primary kinetic isotope effect (k H /k D = 0.84 ± 0.11) disproves a potential direct C−O bond scission mechanism. The observation of nearly complete deuterium incorporation in both the α-C and the β-C is inconsistent with the reverse Mars−van Krevelen mechanism and suggests an enol formation pathway. Evidence consistent with the intermediacy of an oxocarbenium ion as a minor contributor has also been observed. In drawing the conclusions, it was necessary to characterize the facile isotope exchange between surface activated hydrogen and the water solvent. Hydrogenation of a water-soluble olefin, tetra(ethylene glycol) diacrylate (TEGDA) in H 2 /D 2 O revealed predominant incorporation of deuterium instead of hydrogen in the reduced product, confirming the rapid exchange of surface activated hydrogen. The methods used in this study provide clarification about a reaction mechanism currently under debate, and these findings can be applied to other systems involving HDO of linear polyols over metal−metal oxide catalysts, improving catalyst design and utilization of sustainable feedstocks.
TiC oxidises via a combination of spot-oxidation and shrinking core mechanisms, resulting in a mesoporous, high-performance TiO2–TiC composite for bromine production via catalysed HBr oxidation.
ABSTRACT2017 Research Leap/Inovatus Services Ltd. All rights reserved. 10.18775/jibrm.184910.18775/jibrm. -8558.201510.18775/jibrm. .31.3003 URL: http://dx.doi.org/10.18775/jibrm.184910.18775/jibrm. -8558.2015 Borrowing the "Organizational Change Recipients' Belief Scale" instrument developed by Armenakis, Bernserth, Pitts, and Walker, employees and owners of businesses in a quickly changing downtown environment were surveyed to assess similarities and differences in their readiness to change. In addition to added demographic variables, the constructs included from the Armenakis et al. instrument were valence, principal support, efficacy, appropriateness, and discrepancy. Results were mixed. There were no significant differences across industries nor employees vs supervisors/owners. However, significant differences were found across sex, age, and level of education.
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