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Js Lee - One of the best experts on this subject based on the ideXlab platform.

  • Effects of metal Cation on the skeletal isomerization of 1-butene over clinoptilolite
    'Elsevier BV', 2019
    Co-Authors: Hc Lee, Hc Woo, Sh Chung, Hj Kim, Kh Lee, Js Lee
    Abstract:

    Skeletal isomerization of I-butene to isobutene has been investigated over various metal-Cation-exchanged natural clinoptilolite zeolites. The effects of metal Cation exchange were examined by XRD, NH3-TPD, FT-IR, and solid-state NMR to elucidate the controlling factors affecting the selectivity to isobutene. Cobalt-Cation-exchanged natural clinoptilolite zeolite (Co-HNZ) showed a higher selectivity to isobutene compared with that of HNZ at the same conversion of n-butenes under the same reaction conditions, while barium-Cation-exchanged zeolite (Ba-HNZ) exhibited a higher activity but a very low selectivity to isobutene. It could be suggested that the high selectivity over the Co-HNZ catalyst was induced by selective removal of strong acid sites that were responsible for the side reactions of dimerization cracking as well as by imposing an effective constraint on zeolite channels. On the other hand, the high density and easy accessibility of acid sites mainly on the external surface in Ba-HNZ could increase the extent of the bilmolecular reaction pathway, leading to high yields of by-products. Thus, a selective catalyst for skeletal isomerization of 1-butene should satisfy multiple requirements regarding its acid site, namely, strength, type, concentration, and accessibility. (C) 2002 Elsevier Science (USA).X11

  • Effects of metal Cation on the skeletal isomerization of 1-butene over clinoptilolite
    'Elsevier BV', 2019
    Co-Authors: Hc Lee, Hc Woo, Sh Chung, Hj Kim, Kh Lee, Js Lee
    Abstract:

    Skeletal isomerization of I-butene to isobutene has been investigated over various metal-Cation-exchanged natural clinoptilolite zeolites. The effects of metal Cation exchange were examined by XRD, NH3-TPD, FT-IR, and solid-state NMR to elucidate the controlling factors affecting the selectivity to isobutene. Cobalt-Cation-exchanged natural clinoptilolite zeolite (Co-HNZ) showed a higher selectivity to isobutene compared with that of HNZ at the same conversion of n-butenes under the same reaction conditions, while barium-Cation-exchanged zeolite (Ba-HNZ) exhibited a higher activity but a very low selectivity to isobutene. It could be suggested that the high selectivity over the Co-HNZ catalyst was induced by selective removal of strong acid sites that were responsible for the side reactions of dimerization cracking as well as by imposing an effective constraint on zeolite channels. On the other hand, the high density and easy accessibility of acid sites mainly on the external surface in Ba-HNZ could increase the extent of the bilmolecular reaction pathway, leading to high yields of by-products. Thus, a selective catalyst for skeletal isomerization of 1-butene should satisfy multiple requirements regarding its acid site, namely, strength, type, concentration, and accessibility. (C) 2002 Elsevier Science (USA).X1111sciescopu

Hc Lee - One of the best experts on this subject based on the ideXlab platform.

  • Effects of metal Cation on the skeletal isomerization of 1-butene over clinoptilolite
    'Elsevier BV', 2019
    Co-Authors: Hc Lee, Hc Woo, Sh Chung, Hj Kim, Kh Lee, Js Lee
    Abstract:

    Skeletal isomerization of I-butene to isobutene has been investigated over various metal-Cation-exchanged natural clinoptilolite zeolites. The effects of metal Cation exchange were examined by XRD, NH3-TPD, FT-IR, and solid-state NMR to elucidate the controlling factors affecting the selectivity to isobutene. Cobalt-Cation-exchanged natural clinoptilolite zeolite (Co-HNZ) showed a higher selectivity to isobutene compared with that of HNZ at the same conversion of n-butenes under the same reaction conditions, while barium-Cation-exchanged zeolite (Ba-HNZ) exhibited a higher activity but a very low selectivity to isobutene. It could be suggested that the high selectivity over the Co-HNZ catalyst was induced by selective removal of strong acid sites that were responsible for the side reactions of dimerization cracking as well as by imposing an effective constraint on zeolite channels. On the other hand, the high density and easy accessibility of acid sites mainly on the external surface in Ba-HNZ could increase the extent of the bilmolecular reaction pathway, leading to high yields of by-products. Thus, a selective catalyst for skeletal isomerization of 1-butene should satisfy multiple requirements regarding its acid site, namely, strength, type, concentration, and accessibility. (C) 2002 Elsevier Science (USA).X11

  • Effects of metal Cation on the skeletal isomerization of 1-butene over clinoptilolite
    'Elsevier BV', 2019
    Co-Authors: Hc Lee, Hc Woo, Sh Chung, Hj Kim, Kh Lee, Js Lee
    Abstract:

    Skeletal isomerization of I-butene to isobutene has been investigated over various metal-Cation-exchanged natural clinoptilolite zeolites. The effects of metal Cation exchange were examined by XRD, NH3-TPD, FT-IR, and solid-state NMR to elucidate the controlling factors affecting the selectivity to isobutene. Cobalt-Cation-exchanged natural clinoptilolite zeolite (Co-HNZ) showed a higher selectivity to isobutene compared with that of HNZ at the same conversion of n-butenes under the same reaction conditions, while barium-Cation-exchanged zeolite (Ba-HNZ) exhibited a higher activity but a very low selectivity to isobutene. It could be suggested that the high selectivity over the Co-HNZ catalyst was induced by selective removal of strong acid sites that were responsible for the side reactions of dimerization cracking as well as by imposing an effective constraint on zeolite channels. On the other hand, the high density and easy accessibility of acid sites mainly on the external surface in Ba-HNZ could increase the extent of the bilmolecular reaction pathway, leading to high yields of by-products. Thus, a selective catalyst for skeletal isomerization of 1-butene should satisfy multiple requirements regarding its acid site, namely, strength, type, concentration, and accessibility. (C) 2002 Elsevier Science (USA).X1111sciescopu

Claudio Airoldi - One of the best experts on this subject based on the ideXlab platform.

  • some thermodynamic data about amino chrysotile derivatives with nickel and Cobalt Cation interactions in aqueous solution
    Thermochimica Acta, 2001
    Co-Authors: Maria G Fonseca, Jose De Alencar Simoni, Claudio Airoldi
    Abstract:

    Abstract Two silylating agents yielded aminopropyl and propylethylenediamine chrysotile derivative fibers named CRI1 and CRI2. The amount of organic groups of 1.20 and 2.87 mmol per gram of the fibers, were anchored on surface, respectively. The interactions between the amino groups attached to organic chains of these modified chrysotiles and divalent nickel or Cobalt Cations in aqueous solution were followed through calorimetric titrations. The thermal effect obtained from the interactive process was subtracted the respective thermal effect of dilution, which net value was adjusted to a modified Langmuir equation. The adsorption capacities were more pronounced for CRI1 and both processes were associated with complexes formation and the calorimetric data showed two defined steps for this fiber. The enthalpy of interaction was calculated to give the following values for CRI2: −78.61±0.36 and −179.18±6.44 kJ mol −1 for nickel and Cobalt. Exothermic data for CRI1 contrasted to the previous values, giving 35.53±0.50 kJ mol −1 for nickel and 25.73±0.64 kJ mol −1 for Cobalt, which value is related to two individual contributions of 13.94±0.42 and 11.79±0.22 kJ mol −1 . The negative Gibbs free energy values indicated a more favorable reaction for CRI2. A linear correlation was obtained between Gibbs free energy and Pearson’s parameters related to hard–soft properties, suggesting that these processes can be adjusted to acidic–basic interactions. By including copper, the sequence of acidic hardness was Co 2+ >Ni 2+ >Cu 2+ , which is the same order of free energy values found for both investigated systems.

M A Duncan - One of the best experts on this subject based on the ideXlab platform.

  • infrared spectroscopy of rg co h2o complexes rg ar ne he the role of rare gas tag atoms
    Journal of Chemical Physics, 2021
    Co-Authors: Joshua H Marks, Evangelos Miliordos, M A Duncan
    Abstract:

    RGn–Co+(H2O) Cation complexes (RG = Ar, Ne, He) are generated in a supersonic expansion by pulsed laser vaporization. Complexes are mass-selected using a time-of-flight spectrometer and studied with infrared laser photodissociation spectroscopy, measuring the respective mass channels corresponding to the elimination of the rare gas “tag” atom. Spectral patterns and theory indicate that the structures of the ions with a single rare gas atom have this bound to the Cobalt Cation opposite the water moiety in a near-C2v arrangement. The O–H stretch vibrations of the complex are shifted compared to those of water because of the metal Cation charge-transfer interaction; these frequencies also vary systematically with the rare gas atom attached. The efficiencies of photodissociation also vary with the rare gas atoms because of their widely different binding energies to the Cobalt Cation. The spectrum of the argon complex could only be measured when at least three argon atoms were attached. In the case of the helium complex, the low binding energy allows the spectra to be measured for the low-frequency H–O–H scissors bending mode and for the O–D stretches of the deuterated analog. The partially resolved rotational structure for the antisymmetric O–H and O–D stretches reveals the temperature of these complexes (6 K) and establishes the electronic ground state. The helium complex has the same 3B1 ground state as the tag-free complex studied previously by Metz and co-workers [“Dissociation energy and electronic and vibrational spectroscopy of Co+(H2O) and its isotopomers,” J. Phys. Chem. A 117, 1254 (2013)], but the A rotational constant is contaminated by vibrational averaging from the bending motion of the helium.

Sh Chung - One of the best experts on this subject based on the ideXlab platform.

  • Effects of metal Cation on the skeletal isomerization of 1-butene over clinoptilolite
    'Elsevier BV', 2019
    Co-Authors: Hc Lee, Hc Woo, Sh Chung, Hj Kim, Kh Lee, Js Lee
    Abstract:

    Skeletal isomerization of I-butene to isobutene has been investigated over various metal-Cation-exchanged natural clinoptilolite zeolites. The effects of metal Cation exchange were examined by XRD, NH3-TPD, FT-IR, and solid-state NMR to elucidate the controlling factors affecting the selectivity to isobutene. Cobalt-Cation-exchanged natural clinoptilolite zeolite (Co-HNZ) showed a higher selectivity to isobutene compared with that of HNZ at the same conversion of n-butenes under the same reaction conditions, while barium-Cation-exchanged zeolite (Ba-HNZ) exhibited a higher activity but a very low selectivity to isobutene. It could be suggested that the high selectivity over the Co-HNZ catalyst was induced by selective removal of strong acid sites that were responsible for the side reactions of dimerization cracking as well as by imposing an effective constraint on zeolite channels. On the other hand, the high density and easy accessibility of acid sites mainly on the external surface in Ba-HNZ could increase the extent of the bilmolecular reaction pathway, leading to high yields of by-products. Thus, a selective catalyst for skeletal isomerization of 1-butene should satisfy multiple requirements regarding its acid site, namely, strength, type, concentration, and accessibility. (C) 2002 Elsevier Science (USA).X11

  • Effects of metal Cation on the skeletal isomerization of 1-butene over clinoptilolite
    'Elsevier BV', 2019
    Co-Authors: Hc Lee, Hc Woo, Sh Chung, Hj Kim, Kh Lee, Js Lee
    Abstract:

    Skeletal isomerization of I-butene to isobutene has been investigated over various metal-Cation-exchanged natural clinoptilolite zeolites. The effects of metal Cation exchange were examined by XRD, NH3-TPD, FT-IR, and solid-state NMR to elucidate the controlling factors affecting the selectivity to isobutene. Cobalt-Cation-exchanged natural clinoptilolite zeolite (Co-HNZ) showed a higher selectivity to isobutene compared with that of HNZ at the same conversion of n-butenes under the same reaction conditions, while barium-Cation-exchanged zeolite (Ba-HNZ) exhibited a higher activity but a very low selectivity to isobutene. It could be suggested that the high selectivity over the Co-HNZ catalyst was induced by selective removal of strong acid sites that were responsible for the side reactions of dimerization cracking as well as by imposing an effective constraint on zeolite channels. On the other hand, the high density and easy accessibility of acid sites mainly on the external surface in Ba-HNZ could increase the extent of the bilmolecular reaction pathway, leading to high yields of by-products. Thus, a selective catalyst for skeletal isomerization of 1-butene should satisfy multiple requirements regarding its acid site, namely, strength, type, concentration, and accessibility. (C) 2002 Elsevier Science (USA).X1111sciescopu