L'application presente porte sur une composition de revetement comprenant un liant ceramique ... more L'application presente porte sur une composition de revetement comprenant un liant ceramique et des particules de composee inorganiques de cuivre. D'une maniere generale, lesdites particules ont une taille moyenne de moins de 5 micrometres. Dans certaines executions, les particules ont une taille moyenne de plus d'un 1 micrometre. Elles peuvent etre non-photocatalytiques. Le revetement peut aussi etre placee sur une couche structurelle.
Photocatalytic building surfaces can harness sunlight to reduce urban air pollution. The NOx abat... more Photocatalytic building surfaces can harness sunlight to reduce urban air pollution. The NOx abatement capacity of TiO2-coated granules used in roofing products was evaluated for commercial product development. A laboratory test chamber and ancillary setup were built following conditions prescribed by ISO Standard 22197-1. It was validated by exposing reference P25-coated aluminum plates to a 3 L min-1 air flow enriched in 1 ppm NO under UVA irradiation (360 nm, 11.5 W m-²). We characterized prototype granule-surfaced asphalt shingles and loose granules prepared with different TiO2 loadings and post-treatment formulations. Tests performed at surface temperatures of 25 and 60 °C showed that NOx abatement was more effective at the higher temperature. Preliminary tests explored the use of 1 ppm NO2 and of 1 ppm and 0.3 ppm NO/NO2 mixtures. Specimens were aged in a laboratory accelerated weathering apparatus, and by exposure to the outdoor environment over periods that included dry and rainy seasons. Laboratory aging led to higher NO removal and NO2 formation rates, and the same catalyst activation was observed after field exposure with frequent precipitation. However, exposure during the dry season reduced the performance. This inactivation was mitigated by cleaning the surface of field-exposed specimens. Doubling the TiO2 loading led to a 50-150 % increase in NO removal and NOx deposition rates. Application of different post-treatment coatings decreased NO removal rates (21-35%) and NOx deposition rates (26-74%) with respect to untreated granules. The mass balance of nitrogenated species was assessed by extracting granules after UV exposure in a 1 ppm NOenriched atmosphere.
A series of Pt-Au and related phosphine-stabilized cluster compounds have been shown to be excell... more A series of Pt-Au and related phosphine-stabilized cluster compounds have been shown to be excellent catalysts for H2-D2 equilibration (H2 + D2 = 2HD) under homogeneous and heterogeneous conditions. H2-D2 equilibration is a model reaction for catalytic H2 activation. Turnover rates for H D production (ca. 5 s-l for the best catalyst) were comparable to those of activated Pt surfaces. Kinetic data measured under homogeneous conditions (nitrobenzene solvent, 30 OC, 1 atm) showed the following trends in rate: (i) Faster rates were observed as the Au/Pt ratio increased. (ii) Pt-Au clusters gave faster rates than Pd-Au clusters; Au clusters were inactive. (iii) Sixteenelectron clusters were more active than 18-electron clusters; 18-electron hydrido clusters were also very active. These trends suggested that the M-Au bonds may function as active sites for H2 activation (112-H and p3-H bonding occurs in known hydrido clusters) with Pt-Au bonds being more active than Pd-Au bonds. The mechanism for the homogeneous, catalytic H2-D2 equilibration was studied by spectroscopic and kinetic measurements. For the 16-electron cluster [Pt(AuPPh3)8](NO3)2 = M, it is thought to involve the following steps: (1) M + H2 = M(H)2; (2) M(H)2 = M'(H)2 + PPh,; (3) M'(H)2 + D2 = M'(H)z(D)z. Step 1 isdirectlyobservable by NMRspectroscopy, while steps 2 and 3 were implicated by kinetic studies as a function of H2, D2, and metal cluster concentration and by the effect of added PPh3. Step 3, the formation of a 20-electron, tetra(hydrid0, deuterio) species, is rate limiting and its reverse leads to H D production. The mechanism with the hydrido, 18-electron cluster [Pt(H)(PPh& (AuPPh3)7](NO& is also thought to involve PPh3 dissociation followed by the rate-limiting addition of D2 giving a 20-electron, trihydrido species or activated complex. The 20-electron species have not been directly observed. These phosphine-stabilized clusters have deep and narrow hydrophobic channels into the metal core which prevents binding of many larger substrates thus protecting the core from poisoning. This helps explain the high turnover rates for H D production observed with molecular solids of these clusters. This study has shown that phosphinestabilized, mixed-metal cluster compounds are useful as models for polymetallic surface catalysts and that structurereactivity relations have relevance to this important area in catalysis.
... Alexander V. Bulatov,$ Rachel A. T. Could,$ Wayde V. Konze,$ and Louis H. Pignolet&am... more ... Alexander V. Bulatov,$ Rachel A. T. Could,$ Wayde V. Konze,$ and Louis H. Pignolet'.$ Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, and Institute of Chemical Physics, Russian ... (24) Craighead, KL; Felicissimo, A. MP; Nelson, LJ; Krogstad ...
The synthesis and characterization of a series of new mercury containing platinum-gold cluster co... more The synthesis and characterization of a series of new mercury containing platinum-gold cluster compounds are reported. The compound [ (PPh3)Pt(AuPPh3)6(HgNO3)] (NO3) ( l(N03)) was prepared by the addition of metallic mercury to [(PPh3)Pt(AuPPh3)6](NO3)2. Halide derivatives of 1 were prepared by reaction with halides X-(X = C1, Br, I) to give the series [(PPh3)Pt(AuPPh3)6(HgX)]+ (2). Metallic mercury can be displaced from 1 by reaction with CO (1 atm) giving the known carbonyl adduct [(PPh3)(CO)Pt(AuPPh3)6I2+. This reaction is reversible. The first tetrametallic derivatives of Pt-centered, gold cluster compounds [(PPh3)Pt(AuPPh3)6(HgCo C0)4)]+ (3), and [(PPh3)Pt(AuPPh3)5(HgCo(CO)&]+ (4), have been prepared by reaction of NaCo(C0)4 with 1 and [(PPhs)Pt-(AuPPh3)5(HgNO3)2]+, respectively. Compound 1 has been characterized by single crystal X-ray diffraction. 1 crystalizes as a ( C~H S )~O . ( C H~)~C O solvate with the following crystal data: monoclinic P2&, a = 24.968 (7) A, b = 15.848 (9) A, c = 30.60 (1) A, = 92.69 (3)O, V = 12,093 AS, Z = 4, and residuals R = 0.077 and R, = 0.071
Several new cluster compounds have been prepared by reaction of metallic Hg with the 16-electron ... more Several new cluster compounds have been prepared by reaction of metallic Hg with the 16-electron clusters [M(AupPh3)~]"+ (M = Pt, Pd, n = 2; M = Au, n = 3) to form the 20-electron clusters [(Hg)2M(AuPPh3)g12+ (M = Pt, 1; Pd, 2) and [(Hg)2Au(AuPPh3)gI3+ (3). In contrast, reaction of the 16-electron clusters with Hg12+ salts gave the 18-electron clusters [(HgN03)2M(AuPPh3)8I2+ (M = Pt, 6; Pd, 7). The 18-electron, monomercury clusters [(Hg)M(AuPPh&12+ (M = Pt, 4; Pd, 5) were isolated as intermediates in the formation of clusters 1 and 2 and were also prepared by reaction of clusters 1 or 2 with 1 equiv of [M(AuPPh3)g12+ (M = Pt, Pd). Clusters 1-7 have been characterized by spectroscopic and analytical methods, and the nitrate salts of 2 and 4, by single crystal, X-ray diffraction. The crystal data for these compounds are as follows: for 2(NO3)2, orthorhombic Fddd, a = 34.66(2) A, b = 42.09(3) A, c = 39.29(3) A, V = 57 329 A3, Z = 16, residuals R = 0.099 and R, = 0.098 for 1777 observed reflections and 152 variables, Mo Ka radiation; for 4(N03)2, monoclinic P21/n, a = 16.95(2) A, b = 31.60(3) A, c = 25.69(3) A, p = 94.07(7)", V = 13 725 A3, 2 = 4, residuals R = 0.088 and R, = 0.081 for 7504 observed reflections and 441 variables, Mo Ka radiation. The structure of the cluster core of 2(NO3)2
A series of Pt-Au and related phosphine-stabilized cluster compounds have been shown to be excell... more A series of Pt-Au and related phosphine-stabilized cluster compounds have been shown to be excellent catalysts for H2-D2 equilibration (H2+ D2= 2HD) under homogeneous and heterogeneous conditions. H2-D2 equilibration is a model reaction for catalytic H2 ...
L'application presente porte sur une composition de revetement comprenant un liant ceramique ... more L'application presente porte sur une composition de revetement comprenant un liant ceramique et des particules de composee inorganiques de cuivre. D'une maniere generale, lesdites particules ont une taille moyenne de moins de 5 micrometres. Dans certaines executions, les particules ont une taille moyenne de plus d'un 1 micrometre. Elles peuvent etre non-photocatalytiques. Le revetement peut aussi etre placee sur une couche structurelle.
Photocatalytic building surfaces can harness sunlight to reduce urban air pollution. The NOx abat... more Photocatalytic building surfaces can harness sunlight to reduce urban air pollution. The NOx abatement capacity of TiO2-coated granules used in roofing products was evaluated for commercial product development. A laboratory test chamber and ancillary setup were built following conditions prescribed by ISO Standard 22197-1. It was validated by exposing reference P25-coated aluminum plates to a 3 L min-1 air flow enriched in 1 ppm NO under UVA irradiation (360 nm, 11.5 W m-²). We characterized prototype granule-surfaced asphalt shingles and loose granules prepared with different TiO2 loadings and post-treatment formulations. Tests performed at surface temperatures of 25 and 60 °C showed that NOx abatement was more effective at the higher temperature. Preliminary tests explored the use of 1 ppm NO2 and of 1 ppm and 0.3 ppm NO/NO2 mixtures. Specimens were aged in a laboratory accelerated weathering apparatus, and by exposure to the outdoor environment over periods that included dry and rainy seasons. Laboratory aging led to higher NO removal and NO2 formation rates, and the same catalyst activation was observed after field exposure with frequent precipitation. However, exposure during the dry season reduced the performance. This inactivation was mitigated by cleaning the surface of field-exposed specimens. Doubling the TiO2 loading led to a 50-150 % increase in NO removal and NOx deposition rates. Application of different post-treatment coatings decreased NO removal rates (21-35%) and NOx deposition rates (26-74%) with respect to untreated granules. The mass balance of nitrogenated species was assessed by extracting granules after UV exposure in a 1 ppm NOenriched atmosphere.
A series of Pt-Au and related phosphine-stabilized cluster compounds have been shown to be excell... more A series of Pt-Au and related phosphine-stabilized cluster compounds have been shown to be excellent catalysts for H2-D2 equilibration (H2 + D2 = 2HD) under homogeneous and heterogeneous conditions. H2-D2 equilibration is a model reaction for catalytic H2 activation. Turnover rates for H D production (ca. 5 s-l for the best catalyst) were comparable to those of activated Pt surfaces. Kinetic data measured under homogeneous conditions (nitrobenzene solvent, 30 OC, 1 atm) showed the following trends in rate: (i) Faster rates were observed as the Au/Pt ratio increased. (ii) Pt-Au clusters gave faster rates than Pd-Au clusters; Au clusters were inactive. (iii) Sixteenelectron clusters were more active than 18-electron clusters; 18-electron hydrido clusters were also very active. These trends suggested that the M-Au bonds may function as active sites for H2 activation (112-H and p3-H bonding occurs in known hydrido clusters) with Pt-Au bonds being more active than Pd-Au bonds. The mechanism for the homogeneous, catalytic H2-D2 equilibration was studied by spectroscopic and kinetic measurements. For the 16-electron cluster [Pt(AuPPh3)8](NO3)2 = M, it is thought to involve the following steps: (1) M + H2 = M(H)2; (2) M(H)2 = M'(H)2 + PPh,; (3) M'(H)2 + D2 = M'(H)z(D)z. Step 1 isdirectlyobservable by NMRspectroscopy, while steps 2 and 3 were implicated by kinetic studies as a function of H2, D2, and metal cluster concentration and by the effect of added PPh3. Step 3, the formation of a 20-electron, tetra(hydrid0, deuterio) species, is rate limiting and its reverse leads to H D production. The mechanism with the hydrido, 18-electron cluster [Pt(H)(PPh& (AuPPh3)7](NO& is also thought to involve PPh3 dissociation followed by the rate-limiting addition of D2 giving a 20-electron, trihydrido species or activated complex. The 20-electron species have not been directly observed. These phosphine-stabilized clusters have deep and narrow hydrophobic channels into the metal core which prevents binding of many larger substrates thus protecting the core from poisoning. This helps explain the high turnover rates for H D production observed with molecular solids of these clusters. This study has shown that phosphinestabilized, mixed-metal cluster compounds are useful as models for polymetallic surface catalysts and that structurereactivity relations have relevance to this important area in catalysis.
... Alexander V. Bulatov,$ Rachel A. T. Could,$ Wayde V. Konze,$ and Louis H. Pignolet&am... more ... Alexander V. Bulatov,$ Rachel A. T. Could,$ Wayde V. Konze,$ and Louis H. Pignolet'.$ Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, and Institute of Chemical Physics, Russian ... (24) Craighead, KL; Felicissimo, A. MP; Nelson, LJ; Krogstad ...
The synthesis and characterization of a series of new mercury containing platinum-gold cluster co... more The synthesis and characterization of a series of new mercury containing platinum-gold cluster compounds are reported. The compound [ (PPh3)Pt(AuPPh3)6(HgNO3)] (NO3) ( l(N03)) was prepared by the addition of metallic mercury to [(PPh3)Pt(AuPPh3)6](NO3)2. Halide derivatives of 1 were prepared by reaction with halides X-(X = C1, Br, I) to give the series [(PPh3)Pt(AuPPh3)6(HgX)]+ (2). Metallic mercury can be displaced from 1 by reaction with CO (1 atm) giving the known carbonyl adduct [(PPh3)(CO)Pt(AuPPh3)6I2+. This reaction is reversible. The first tetrametallic derivatives of Pt-centered, gold cluster compounds [(PPh3)Pt(AuPPh3)6(HgCo C0)4)]+ (3), and [(PPh3)Pt(AuPPh3)5(HgCo(CO)&]+ (4), have been prepared by reaction of NaCo(C0)4 with 1 and [(PPhs)Pt-(AuPPh3)5(HgNO3)2]+, respectively. Compound 1 has been characterized by single crystal X-ray diffraction. 1 crystalizes as a ( C~H S )~O . ( C H~)~C O solvate with the following crystal data: monoclinic P2&, a = 24.968 (7) A, b = 15.848 (9) A, c = 30.60 (1) A, = 92.69 (3)O, V = 12,093 AS, Z = 4, and residuals R = 0.077 and R, = 0.071
Several new cluster compounds have been prepared by reaction of metallic Hg with the 16-electron ... more Several new cluster compounds have been prepared by reaction of metallic Hg with the 16-electron clusters [M(AupPh3)~]"+ (M = Pt, Pd, n = 2; M = Au, n = 3) to form the 20-electron clusters [(Hg)2M(AuPPh3)g12+ (M = Pt, 1; Pd, 2) and [(Hg)2Au(AuPPh3)gI3+ (3). In contrast, reaction of the 16-electron clusters with Hg12+ salts gave the 18-electron clusters [(HgN03)2M(AuPPh3)8I2+ (M = Pt, 6; Pd, 7). The 18-electron, monomercury clusters [(Hg)M(AuPPh&12+ (M = Pt, 4; Pd, 5) were isolated as intermediates in the formation of clusters 1 and 2 and were also prepared by reaction of clusters 1 or 2 with 1 equiv of [M(AuPPh3)g12+ (M = Pt, Pd). Clusters 1-7 have been characterized by spectroscopic and analytical methods, and the nitrate salts of 2 and 4, by single crystal, X-ray diffraction. The crystal data for these compounds are as follows: for 2(NO3)2, orthorhombic Fddd, a = 34.66(2) A, b = 42.09(3) A, c = 39.29(3) A, V = 57 329 A3, Z = 16, residuals R = 0.099 and R, = 0.098 for 1777 observed reflections and 152 variables, Mo Ka radiation; for 4(N03)2, monoclinic P21/n, a = 16.95(2) A, b = 31.60(3) A, c = 25.69(3) A, p = 94.07(7)", V = 13 725 A3, 2 = 4, residuals R = 0.088 and R, = 0.081 for 7504 observed reflections and 441 variables, Mo Ka radiation. The structure of the cluster core of 2(NO3)2
A series of Pt-Au and related phosphine-stabilized cluster compounds have been shown to be excell... more A series of Pt-Au and related phosphine-stabilized cluster compounds have been shown to be excellent catalysts for H2-D2 equilibration (H2+ D2= 2HD) under homogeneous and heterogeneous conditions. H2-D2 equilibration is a model reaction for catalytic H2 ...
Uploads
Papers by Rachael Gould