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Torben R Jensen - One of the best experts on this subject based on the ideXlab platform.

  • effect of eutectic melting reactive hydride composites and nanoconfinement on decomposition and reversibility of libh4 kbh4
    Journal of Physical Chemistry C, 2015
    Co-Authors: Elsa Roedern, Bjarne R. S. Hansen, Torben R Jensen
    Abstract:

    Eutectic melting, reactive hydride composites, and nanoconfinement have the potential to improve the reversible hydrogen storage properties in metal Borohydrides. We study and compare the combined effect of all three methods on reversible hydrogen release and uptake of the eutectic melting lithium Potassium Borohydride system, 0.725LiBH4–0.275KBH4, with low melting temperature (Tm = 105 °C). The eutectic mixture and reactive hydride composites of the eutectic mixture with Mg or MgH2 are melt infiltrated into a CO2 activated nanoporous carbon scaffold, and their properties are compared to those of bulk samples. The decomposition of 0.725LiBH4–0.275KBH4 and the reactive hydride composites initiates simultaneously with the melting at 105 °C, but the decomposition remains slow until higher temperatures are reached (T > 300 °C). Eutectic melting appears to improve kinetics of hydrogen release and absorption, while nanoconfinement lowers the main hydrogen release temperature in the first cycle by up to 200 °C. ...

  • eutectic melting of libh4 kbh4
    Physical Chemistry Chemical Physics, 2014
    Co-Authors: Elsa Roedern, Torben R Jensen
    Abstract:

    Eutectic melting in mixtures of alkali and alkali earth metal Borohydrides can pave the way for new applications as fast ionic conductors, and facilitate hydrogen release by low temperature chemical reactions and convenient nanoconfinement. Here, we determine the eutectic composition for the lithium Potassium Borohydride system, 0.725LiBH4–0.275KBH4, with the lowest melting point, Tmelt ∼105 °C, of all known alkali and alkali earth metal Borohydride mixtures. Mechanochemistry and manual mixing of LiBH4–KBH4 mixtures facilitate the formation of LiK(BH4)2. However, the melting or heat treatments used in this work do not produce LiK(BH4)2. The bimetallic Borohydride dissociates into the monometallic Borohydrides at ∼95 °C and partial melting occurs at ∼105 °C. Analysis of the unit cell volumes of LiBH4, KBH4 and LiK(BH4)2 in the temperature range 25 to 90 °C indicates that the formation of the bimetallic Borohydride is facilitated by a more dense packing as compared to the reactants. Thus, LiK(BH4)2 is considered metastable and the formation is pressure induced. A phase diagram for the LiBH4–KBH4 system is established, which illustrates the low eutectic melting point and the stability range for the bimetallic Borohydride, LiK(BH4)2.

  • eutectic melting of libh4 kbh4
    Physical Chemistry Chemical Physics, 2014
    Co-Authors: Elsa Roedern, Torben R Jensen
    Abstract:

    Eutectic melting in mixtures of alkali and alkali earth metal Borohydrides can pave the way for new applications as fast ionic conductors, and facilitate hydrogen release by low temperature chemical reactions and convenient nanoconfinement. Here, we determine the eutectic composition for the lithium Potassium Borohydride system, 0.725LiBH4–0.275KBH4, with the lowest melting point, Tmelt ∼105 °C, of all known alkali and alkali earth metal Borohydride mixtures. Mechanochemistry and manual mixing of LiBH4–KBH4 mixtures facilitate the formation of LiK(BH4)2. However, the melting or heat treatments used in this work do not produce LiK(BH4)2. The bimetallic Borohydride dissociates into the monometallic Borohydrides at ∼95 °C and partial melting occurs at ∼105 °C. Analysis of the unit cell volumes of LiBH4, KBH4 and LiK(BH4)2 in the temperature range 25 to 90 °C indicates that the formation of the bimetallic Borohydride is facilitated by a more dense packing as compared to the reactants. Thus, LiK(BH4)2 is considered metastable and the formation is pressure induced. A phase diagram for the LiBH4–KBH4 system is established, which illustrates the low eutectic melting point and the stability range for the bimetallic Borohydride, LiK(BH4)2.

Xiuwen Cheng - One of the best experts on this subject based on the ideXlab platform.

  • visible light driven photocatalytic decomposition of penicillin g by ti3 self doped tio2 nano catalyst through response surface methodology
    Journal of The Taiwan Institute of Chemical Engineers, 2018
    Co-Authors: Xiaoyong Deng, Xiuwen Cheng, Qingfeng Cheng, Ruonan Guo
    Abstract:

    Abstract In present study, Ti3+ self-doped TiO2 (r-TiO2) nano-catalyst was successfully fabricated by one-step solution reduction treatment in the presence of Potassium Borohydride. The self-doping process can induce the generation of Ti3+ and oxygen vacancy (Ov) to form a new energy level in the forbidden band of TiO2. Moreover, physicochemical properties of the resulting samples were studied by series of techniques. Results suggest that r-TiO2 nano-catalyst exhibits remarkable enhancement of visible light harvesting and higher charge separation efficiency. In order to investigate the influence factors on degradation of penicillin G (PENG), the experimental design was made using central composite method (CCD) of response surface methodology (RSM). For this purpose, the r-TiO2 dosage, PENG concentration and initial pH value were selected as critical parameters. Results indicate the r-TiO2 dosage and initial pH possess higher influences. Besides, the highest photocatalytic efficiency of PENG (98.3%) can be obtained under the optimal conditions of r-TiO2 dosage 50 mg, PENG concentration 100 mg/L and initial pH 5.5, respectively.

  • fabrication of ag ag2o reduced tio2 nanophotocatalyst and its enhanced visible light driven photocatalytic performance for degradation of diclofenac solution
    Applied Catalysis B-environmental, 2017
    Co-Authors: Xiaoyong Deng, Qi Meng, Xiuwen Cheng, Xiaoli Li, Qingfeng Cheng
    Abstract:

    Abstract In this study, Ag-Ag2O/reduced TiO2 (denoted as Ag-Ag2O/r-TiO2) nano-photocatalyst had been fabricated through one-step solution reduction strategy in the presence of Potassium Borohydride. Afterwards, physicochemical properties of the resulting samples were investigated by scanning electron microscope (SEM), N2 adsorption/desorption isotherms, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV-vis DRS), electron spin resonance (ESR) and time-resolved surface photovoltage (TR-SPV) techniques. Results indicated that Potassium Borohydride treatment could simutaneously induce the generation of Ti3+ self-doping energy level between the forbidden band of TiO2 and metallic Ag species existed in the forms of Ag0 and Ag2O nanocrystalline, thereby resulting in the greatly enhanced visible light absorbance and photoinduced charge separation efficiency. In addition, the visible light driven (VLD) photocatalytic (PC) performance was evaluated through the degradation of diclofenac and generation of ·OH radicals. As-expected, Ag-Ag2O/r-TiO2 sample exhibited higher VLD PC performance and larger generation amount of ·OH radicals. Furthermore, the enhanced VLD PC mechanism was proposed and confirmed, which was mainly attributed to the synergistic effect originated from the localized SPR of Ag0 nanocrystalline and Ti3+ self-doping which responsible for the intense visible light absorbance, high photoinduced charge separation efficiency and VLD PC performance.

Qingfeng Cheng - One of the best experts on this subject based on the ideXlab platform.

  • visible light driven photocatalytic decomposition of penicillin g by ti3 self doped tio2 nano catalyst through response surface methodology
    Journal of The Taiwan Institute of Chemical Engineers, 2018
    Co-Authors: Xiaoyong Deng, Xiuwen Cheng, Qingfeng Cheng, Ruonan Guo
    Abstract:

    Abstract In present study, Ti3+ self-doped TiO2 (r-TiO2) nano-catalyst was successfully fabricated by one-step solution reduction treatment in the presence of Potassium Borohydride. The self-doping process can induce the generation of Ti3+ and oxygen vacancy (Ov) to form a new energy level in the forbidden band of TiO2. Moreover, physicochemical properties of the resulting samples were studied by series of techniques. Results suggest that r-TiO2 nano-catalyst exhibits remarkable enhancement of visible light harvesting and higher charge separation efficiency. In order to investigate the influence factors on degradation of penicillin G (PENG), the experimental design was made using central composite method (CCD) of response surface methodology (RSM). For this purpose, the r-TiO2 dosage, PENG concentration and initial pH value were selected as critical parameters. Results indicate the r-TiO2 dosage and initial pH possess higher influences. Besides, the highest photocatalytic efficiency of PENG (98.3%) can be obtained under the optimal conditions of r-TiO2 dosage 50 mg, PENG concentration 100 mg/L and initial pH 5.5, respectively.

  • fabrication of ag ag2o reduced tio2 nanophotocatalyst and its enhanced visible light driven photocatalytic performance for degradation of diclofenac solution
    Applied Catalysis B-environmental, 2017
    Co-Authors: Xiaoyong Deng, Qi Meng, Xiuwen Cheng, Xiaoli Li, Qingfeng Cheng
    Abstract:

    Abstract In this study, Ag-Ag2O/reduced TiO2 (denoted as Ag-Ag2O/r-TiO2) nano-photocatalyst had been fabricated through one-step solution reduction strategy in the presence of Potassium Borohydride. Afterwards, physicochemical properties of the resulting samples were investigated by scanning electron microscope (SEM), N2 adsorption/desorption isotherms, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV-vis DRS), electron spin resonance (ESR) and time-resolved surface photovoltage (TR-SPV) techniques. Results indicated that Potassium Borohydride treatment could simutaneously induce the generation of Ti3+ self-doping energy level between the forbidden band of TiO2 and metallic Ag species existed in the forms of Ag0 and Ag2O nanocrystalline, thereby resulting in the greatly enhanced visible light absorbance and photoinduced charge separation efficiency. In addition, the visible light driven (VLD) photocatalytic (PC) performance was evaluated through the degradation of diclofenac and generation of ·OH radicals. As-expected, Ag-Ag2O/r-TiO2 sample exhibited higher VLD PC performance and larger generation amount of ·OH radicals. Furthermore, the enhanced VLD PC mechanism was proposed and confirmed, which was mainly attributed to the synergistic effect originated from the localized SPR of Ag0 nanocrystalline and Ti3+ self-doping which responsible for the intense visible light absorbance, high photoinduced charge separation efficiency and VLD PC performance.

Elsa Roedern - One of the best experts on this subject based on the ideXlab platform.

  • effect of eutectic melting reactive hydride composites and nanoconfinement on decomposition and reversibility of libh4 kbh4
    Journal of Physical Chemistry C, 2015
    Co-Authors: Elsa Roedern, Bjarne R. S. Hansen, Torben R Jensen
    Abstract:

    Eutectic melting, reactive hydride composites, and nanoconfinement have the potential to improve the reversible hydrogen storage properties in metal Borohydrides. We study and compare the combined effect of all three methods on reversible hydrogen release and uptake of the eutectic melting lithium Potassium Borohydride system, 0.725LiBH4–0.275KBH4, with low melting temperature (Tm = 105 °C). The eutectic mixture and reactive hydride composites of the eutectic mixture with Mg or MgH2 are melt infiltrated into a CO2 activated nanoporous carbon scaffold, and their properties are compared to those of bulk samples. The decomposition of 0.725LiBH4–0.275KBH4 and the reactive hydride composites initiates simultaneously with the melting at 105 °C, but the decomposition remains slow until higher temperatures are reached (T > 300 °C). Eutectic melting appears to improve kinetics of hydrogen release and absorption, while nanoconfinement lowers the main hydrogen release temperature in the first cycle by up to 200 °C. ...

  • eutectic melting of libh4 kbh4
    Physical Chemistry Chemical Physics, 2014
    Co-Authors: Elsa Roedern, Torben R Jensen
    Abstract:

    Eutectic melting in mixtures of alkali and alkali earth metal Borohydrides can pave the way for new applications as fast ionic conductors, and facilitate hydrogen release by low temperature chemical reactions and convenient nanoconfinement. Here, we determine the eutectic composition for the lithium Potassium Borohydride system, 0.725LiBH4–0.275KBH4, with the lowest melting point, Tmelt ∼105 °C, of all known alkali and alkali earth metal Borohydride mixtures. Mechanochemistry and manual mixing of LiBH4–KBH4 mixtures facilitate the formation of LiK(BH4)2. However, the melting or heat treatments used in this work do not produce LiK(BH4)2. The bimetallic Borohydride dissociates into the monometallic Borohydrides at ∼95 °C and partial melting occurs at ∼105 °C. Analysis of the unit cell volumes of LiBH4, KBH4 and LiK(BH4)2 in the temperature range 25 to 90 °C indicates that the formation of the bimetallic Borohydride is facilitated by a more dense packing as compared to the reactants. Thus, LiK(BH4)2 is considered metastable and the formation is pressure induced. A phase diagram for the LiBH4–KBH4 system is established, which illustrates the low eutectic melting point and the stability range for the bimetallic Borohydride, LiK(BH4)2.

  • eutectic melting of libh4 kbh4
    Physical Chemistry Chemical Physics, 2014
    Co-Authors: Elsa Roedern, Torben R Jensen
    Abstract:

    Eutectic melting in mixtures of alkali and alkali earth metal Borohydrides can pave the way for new applications as fast ionic conductors, and facilitate hydrogen release by low temperature chemical reactions and convenient nanoconfinement. Here, we determine the eutectic composition for the lithium Potassium Borohydride system, 0.725LiBH4–0.275KBH4, with the lowest melting point, Tmelt ∼105 °C, of all known alkali and alkali earth metal Borohydride mixtures. Mechanochemistry and manual mixing of LiBH4–KBH4 mixtures facilitate the formation of LiK(BH4)2. However, the melting or heat treatments used in this work do not produce LiK(BH4)2. The bimetallic Borohydride dissociates into the monometallic Borohydrides at ∼95 °C and partial melting occurs at ∼105 °C. Analysis of the unit cell volumes of LiBH4, KBH4 and LiK(BH4)2 in the temperature range 25 to 90 °C indicates that the formation of the bimetallic Borohydride is facilitated by a more dense packing as compared to the reactants. Thus, LiK(BH4)2 is considered metastable and the formation is pressure induced. A phase diagram for the LiBH4–KBH4 system is established, which illustrates the low eutectic melting point and the stability range for the bimetallic Borohydride, LiK(BH4)2.

Asım Balbay - One of the best experts on this subject based on the ideXlab platform.

  • Semi-methanolysis reaction of Potassium Borohydride with phosphoric acid for effective hydrogen production
    International Journal of Hydrogen Energy, 2018
    Co-Authors: Asım Balbay, Cafer Saka
    Abstract:

    Abstract The methanol and water solvents were used for the production of hydrogen from Potassium Borohydride. In addition, phosphoric acid was selected as the green catalyst so that this semi-methanolysis reaction would be more effective for the first time. The semi-methanolysis of Potassium Borohydride is investigated depend on Potassium Borohydride, phosphoric acid concentrations and temperatures. The maximum normalized hydrogen production rate obtained from this semi-methanolysis reaction with 1 M phosphoric acid as a catalyst was 5779 ml min −1 g−1. In addition, this semi-methanolysis reaction was completed in 5 s. Kinetic studies have been carried out with the power law kinetic model. The activation energy obtained for this semi-methanolysis reaction is 1.45 kJ mol−1.

  • Fast and effective hydrogen production from ethanolysis and hydrolysis reactions of Potassium Borohydride using phosphoric acid
    International Journal of Hydrogen Energy, 2018
    Co-Authors: Cafer Saka, Asım Balbay
    Abstract:

    Abstract The hydrogen production from Potassium Borohydride (KBH4) with the ethanolysis and hydrolysis reactions using the phosphoric acid as a catalyst is performed for the first time. KBH4 concentration, phosphoric acid concentration and temperature effects were investigated for the optimum hydrogen production from ethanolysis and hydrolysis reactions of KBH4. The maximum hydrogen production rates in the ethanolysis and hydrolysis reactions with 1 M phosphoric acid are 6423 and 4296 ml min−1g−1, respectively. At the same time, the ethanolysis and hydrolysis reactions with the 1 M acid concentration were completed within 7 and 9 s, respectively. The total conversions obtained for the volume ratio of KBH4/acid of (1:1) were 100%. The power law kinetic model is performed for the kinetic studies. The activation energies for the ethanolysis and hydrolysis reactions of KBH4 using phosphoric acid are found as 2.98 and 2.60 kJ mol−1.

  • effect of acid addition on hydrogen production from Potassium Borohydride hydrolysis
    Energy Sources Part A-recovery Utilization and Environmental Effects, 2017
    Co-Authors: Asım Balbay, Omer şahin, Cafer Saka
    Abstract:

    ABSTRACTThis is the first study to produce hydrogen from the Potassium Borohydride (KBH4) hydrolysis using boric acid (H3BO3). The effect of H3BO3 addition on the hydrogen production via KBH4 hydrolysis was investigated for different H3BO3 and KBH4 molar ratios. In addition, the temperature effect on the hydrolysis reaction was investigated at different temperatures. H3BO3 showed good catalytic activity to produce hydrogen from KBH4 hydrolysis. Activation energy to produce hydrogen from KBH4 hydrolysis was found to be 20.31 kJ/mol. This work also includes kinetic information for the hydrolysis of KBH4. According to the kinetic studies, the reaction between H3BO3 and KBH4 had a reaction order of 0.24 against the H3BO3 concentration, while it had a reaction order of 0.16 against the KBH4 concentration.