Determining adsorbate configuration on alumina surfaces with 13C nuclear magnetic resonance relaxation time analysis

Relative strengths of surface interaction for individual carbon atoms in acyclic and cyclic hydrocarbons adsorbed on alumina surfaces are determined using chemically resolved 13C nuclear magnetic resonance (NMR) T1 relaxation times. The ratio of relaxation times for the adsorbed atoms T1,ads to the bulk liquid relaxation time T1,bulk provides an indication of the mobility of the atom. Hence a low T1,ads/T1,bulk ratio indicates a stronger surface interaction. The carbon atoms associated with unsaturated bonds in the molecules are seen to exhibit a larger reduction in T1 on adsorption relative to the aliphatic carbons, consistent with adsorption occurring through the carbon-carbon multiple bonds. The relaxation data are interpreted in terms of proximity of individual carbon atoms to the alumina surface and adsorption conformations are inferred. Furthermore, variations of interaction strength and molecular configuration have been explored as a function of adsorbate coverage, temperature, surface pre-treatment, and in the presence of co-adsorbates. This relaxation time analysis is appropriate for studying the behaviour of hydrocarbons adsorbed on a wide range of catalyst support and supported-metal catalyst surfaces, and offers the potential to explore such systems under realistic operating conditions when multiple chemical components are present at the surface

Hydrotreating the bitumen-derived hydrocarbon liquid produced in a fluidized-bed pyrolysis reactor

The pyrolysis of bitumen-impregnated sandstone produces three primary product streams: C{sub 1}-C{sub 4} hydrocarbons gases, a C{sub 5}{sup +} total liquid product, and a carbonaceous residue on the spent sand. The bitumen-derived hydrocarbon liquid was significantly upgraded relative to the native bitumen: it had a higher API gravity, lower Conradson carbon residue, asphaltene content, pour point and viscosity and a reduced distillation endpoint relative to the native bitumen. The elemental composition was little different from that of the native bitumen except for the hydrogen content which was lower. The bitumen-derived liquid produced in a 4-inch diameter fluidized-bed reactor from the Whiterocks tar sand deposit has been hydrotreated in a fixed-bed reactor to determine the extent of upgrading as a function of process operating variables. The extent of denitrogenation and desulfurization of the bitumen-derived liquid was used to monitor catalyst activity as a function of process operating variables and to estimate the extent of catalyst deactivation as a function of time on-stream. The apparent kinetics for the nitrogen and sulfur removal reactions were determined. Product distribution and yield data were also obtained

Hydrotreating the bitumen-derived hydrocarbon liquid produced in a fluidized-bed pyrolysis reactor

The pyrolysis of bitumen-impregnated sandstone produces three primary product streams: C{sub 1}-C{sub 4} hydrocarbons gases, a C{sub 5}{sup +} total liquid product, and a carbonaceous residue on the spent sand. The bitumen-derived hydrocarbon liquid was significantly upgraded relative to the native bitumen: it had a higher API gravity, lower Conradson carbon residue, asphaltene content, pour point and viscosity and a reduced distillation endpoint relative to the native bitumen. The elemental composition was little different from that of the native bitumen except for the hydrogen content which was lower. The bitumen-derived liquid produced in a 4-inch diameter fluidized-bed reactor from the Whiterocks tar sand deposit has been hydrotreated in a fixed-bed reactor to determine the extent of upgrading as a function of process operating variables. The extent of denitrogenation and desulfurization of the bitumen-derived liquid was used to monitor catalyst activity as a function of process operating variables and to estimate the extent of catalyst deactivation as a function of time on-stream. The apparent kinetics for the nitrogen and sulfur removal reactions were determined. Product distribution and yield data were also obtained

Dinitrogen Complexes Supported by Tris(phosphino)silyl Ligands

The tetradentate tris(phosphino)silyl ligand [Si^P(iPr)_3] ([SiP^(iPr)_3] = [Si(o-C_6H_4P^(iPr)_2)_3]−) has been prepared, and its complexation with iron, cobalt, nickel, and iridium precursors has been explored. Several coordination complexes have been thoroughly characterized and are described. These include, for example, the divalent trigonal bipyramidal metal chlorides [SiP^(iPr)_3]M−Cl (M = Fe, Co, Ni), as well as the monovalent dinitrogen adducts [SiP^(iPr)_3]M−N_2 (M = Fe, Co, Ir), which are compared with related [SiP^(Ph)_3]M−Cl and [SiP^(Ph)_3]M−N_2 species (M = Fe, Co). Complexes of this type represent the first examples of terminal dinitrogen adducts of monovalent iron, and the ligand architecture allows examination of a unique class of dinitrogen adducts with a trans-disposed silyl donor. Oxidation of the appropriate [SiP^(R)_3]M−N_2 precursors affords the divalent iron triflate [SiP^(Ph)_3]Fe(OTf) and trivalent cobalt triflate {[SiP^(iPr)_3]Co(OTf)}{OTf} complexes, which are of interest for group transfer studies because of the presence of a labile triflate ligand. Comparative electrochemical, structural, and spectroscopic data are provided for these complexes

The effects of music choice on task performance: A study of the impact of self-selected and experimenter-selected music on driving game performance and experience

Music listening in everyday life tends to accompany the completion of other everyday activities in a highly personalised manner. However, music and task performance studies have tended to be experimenter-centred and contextually isolated, largely independent of the listener s music practices and preference. The present study adopted a listener-centred approach to compare the effects of self-selected and experimenter-selected music (high and low arousal), on concurrent activity performance and experience. 125 participants completed three laps of a driving game in either (i) silence (ii) car sounds alone; car sounds with the addition of (iii) self-selected music, (iv) High-Arousal music or (v) Low-Arousal music. Three performance measures (accuracy-collisions, time-ms, and speed-mph) and 5 experience measures (distraction, liking, appropriateness, enjoyment, and tension-anxiety) were taken. Participants exposed to their self-selected music were most efficient, perceived lowest distraction, highest enjoyment, liking and appropriateness, and experienced a reduction in tension-anxiety. In contrast, performance and experience were poorest when exposed to High-Arousal experimenter-selected music. Participants were most inaccurate, perceived highest distraction, lowest liking, enjoyment and appropriateness, and experienced an increase in tension-anxiety. Collectively, the findings highlight the efficacy of self-selected music as a tool to optimise response in the everyday activity context for which it is selected. Accordingly, the results are discussed in relation to potential implications for the performance and experience of concurrent tasks such as video games. Additionally, the discussion highlights theories of attention-distraction, arousal and affect modification, and subjective experiences of music listening