Yu-Wen Chen | National Central University (original) (raw)

Papers by Yu-Wen Chen

Chinese Journal of Catalysis, 2013

Mo and La have been independently reported to be good promoters of NiB nanocluster in the hydroge... more Mo and La have been independently reported to be good promoters of NiB nanocluster in the hydrogenation of para-chloronitrobenzene (p-CNB). However, a bi-promoter effect of Mo and La in NiB catalysts has not previously been investigated. In this work, a series of La-Mo-doped, nanosized NiB catalysts with different La contents were prepared by chemical reduction and were characterized by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The liquid-phase hydrogenation of p-CNB was carried out in a batch reactor at 333 K, 1.2 MPa H2 pressure and at a spinning rate of 500 r/min. Even doping a small amount of La in NiMoB had a significant effect on its activity and selectivity to p-chloroaniline. The addition of an appropriate amount of La suppressed the growth and long-range order of NiMoB and helped the NiMoB maintain its amorphous state. La was determined to be present in its oxide form and to act as a spacer, preventing NiMoB from sintering and aggregation. However, a high amount of La had an opposite effect, and the optimum ratio of La:Ni was 0.2.

C, 2021

A series of PtRu/carbon black catalysts were prepared by means of deposition-precipitation and re... more A series of PtRu/carbon black catalysts were prepared by means of deposition-precipitation and reduced by various reducing agents. NaBH4, HCHO and NaH2PO2, respectively, were used as the reduction agents. Some of the samples were reduced by various amounts of NaH2PO2 to investigate the effects of P/Pt ratios on the characteristics and activity of the catalyst. These catalysts were characterized by X-ray diffraction and transmission electron microscopy. The components of these catalysts were detected by X-ray fluorescence, X-ray photoelectron microscopy, and extended X-ray absorption of fine structures (EXAFS). The methanol oxidation ability of the catalysts was tested by cyclic voltammetry measurement. The results show that NaH2PO2 could effectively reduce the particle size of PtRu metal. It can suppress the growth of metal particles. In addition, the P/Pt ratio is crucial. The catalyst reduced by NaH2PO2 with a P/Pt ratio of 1.2 had the highest activity among all catalysts. It had ...

Materials, 2021

In this study, high-surface-area carbon black is used to support PtRu. In order to increase the f... more In this study, high-surface-area carbon black is used to support PtRu. In order to increase the functional groups on the surface of carbon black and to have a more homogenous dispersed PtRu metal, the surface of carbon black is functionalized by H2O2. PtRu/carbon black is synthesized by the deposition–precipitation method. NaH2PO2 is used as the reducing agent in preparation. These catalysts are characterized by N2 sorption, temperature-programmed desorption, X-ray diffraction, transmission electron microscope, and X-ray photoelectron spectroscopy. The methanol oxidation ability of the catalyst is tested by cyclic voltammetry measurement. Using H2O2 to modify carbon black can increase the amount of functional groups on the surface, thereby increasing the metal dispersion and decreasing metal particle size. NaH2PO2 as a reducing agent can suppress the growth of metal particles. The best modified carbon black catalyst is the one modified with 30% H2O2. The methanol oxidation activity ...

Catalysis Communications, 2007

Modern Research in Catalysis, 2013

The effects of palladium addition and the reduction methods on Au/TiO 2 were investigated. Pd was... more The effects of palladium addition and the reduction methods on Au/TiO 2 were investigated. Pd was loaded on TiO 2 firstly by incipient-wetness impregnation, Au was then loaded by deposition-precipitation method. The nominal loadings of Au and Pd were 1 wt% and 0.01 wt%. The bimetallic catalysts were reduced by heating at 453 K, by flowing H 2 at 423 K, or by NaBH 4 at 298 K. The catalysts were characterized by ICP, XRD, TEM, HRTEM, TPR and XPS. Hydrogenation of p-chloronitrobenzene was carried out at 1.2 MPa H 2 pressure and 353 K. The results showed that even adding very small amount of Pd could enhance activity and selectivity of p-chloroaniline significantly. Pd and Au formed alloy and Pd could donate partial electron to Au. Pd metal on the surface of alloy could adsorb hydrogen and enhanced the activity. The pretreatment methods did not change particle size significantly, all were below 4 nm. The sample reduced by NaBH 4 could have higher concentration of Au 0 and sustain small Au particle size, resulting in high activity.

OALib, 2014

A series of Ag@TiO 2 catalysts with core-shell structure were successfully synthesized by a sol-g... more A series of Ag@TiO 2 catalysts with core-shell structure were successfully synthesized by a sol-gel method. The samples were prepared by a sol-gel method using silver nitrate, hydrazine, cetyltrimethylammonium bromide and titanium tetra-isopropoxide as the starting materials. The catalysts were characterized by ICP-MS, XRD, TEM, HRTEM and XPS. The results indicated that the silver core was in metallic state and the TiO 2 shell was in anatase state. The size of Ag nanoparticles in core was about 5 and 10 nm, and the shell size of titanium dioxide was 10 and 20 nm. The core was single crystalline Ag nanoparticle and the shell was made up of many TiO 2 nanoparticles. The photocatalytic activity of Ag@TiO 2 was much higher than that of bare TiO 2. Large amounts of hydroxyl groups were present on the surface of TiO 2. The catalysts which were treated by hydrothermal method had the higher lattice oxide percentage and higher photocatalytic activities. The core-shell structure can prevent Ag from aggregation.

Journal of Catalysts, 2013

A series of Au/-TiO2 with various Co/Ti ratios prepared. /TiO2 was prepared by incipient wetness ... more A series of Au/-TiO2 with various Co/Ti ratios prepared. /TiO2 was prepared by incipient wetness impregnation with aqueous solution of cobalt nitrate. Au catalysts were prepared by deposition-precipitation (DP) method at pH 7 and 338 K. The catalysts were characterized by inductively coupled plasma-mass spectrometry, temperature programming reduction, X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The reaction was carried out in a fixed bed reactor with a feed containing 1% CO in air at weight hourly space velocities of 120,000 mL/h g and 180,000 mL/h g. High gold dispersion and narrow particle size distribution were obtained by DP method. The addition of into Au/TiO2 enhanced the activity of CO oxidation significantly. Au/5% -TiO2 had the highest catalyst among all the catalysts. was mainly in the form of nanosize Co3O4 which could stabilize the Au nanoparticles. donated partial electrons...

Modern Research in Catalysis, 2013

A series of Au/CuO x-TiO 2 with various Cu/Ti ratios were prepared. CuO x /TiO 2 was prepared by ... more A series of Au/CuO x-TiO 2 with various Cu/Ti ratios were prepared. CuO x /TiO 2 was prepared by incipient-wetness impregnation with aqueous solution of copper nitrate. Au catalysts were prepared by deposition-precipitation method at pH 7 and 338 K. The catalysts were characterized by inductively-coupled plasma-mass spectrometry, temperature programming reduction, X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The reaction was carried out in a fixed bed reactor with a feed containing 1% CO in air at WHSV of 120,000 mL/h•g. High gold dispersion and narrow size distribution was obtained. The addition of CuO x in Au/TiO 2 enhanced the activity on CO oxidation significantly. CuO x was in amorphous state which could stabilize the Au nanoparticles. Cu was in Cu 1+ state. Cu donated partial electrons to Au. The interactions among Au, Cu 1+ and TiO 2 account for the high catalytic activity for CO oxidation. The significant promotional effect of CuO x on CO oxidation at low temperature was demonstrated.

The Journal of …, 2009

NiO with novel flower-like morphology was prepared by using a two-step, template-and surfactant-f... more NiO with novel flower-like morphology was prepared by using a two-step, template-and surfactant-free, environmentally friendly method. Flower-like NiO was composed of many irregular nanosheets that were assembled together by weak interactions. The as-prepared ...

Catalysts

The aim of this study was to investigate the effects of reaction temperature on the photocatalyti... more The aim of this study was to investigate the effects of reaction temperature on the photocatalytic activity of TiO2 with Pd and Cu cocatalysts. N2 sorption, transmission electron microscopy and high-resolution transmission electron microscopy were used to characterize the specific surface area, pore volume, pore size, morphology and metal distribution of the catalysts. The photocatalytic destruction of methylene blue under UV light irradiation was used to test its activity. The concentration of methylene blue in water was determined by UV-vis spectrophotometer. Pd/TiO2 catalyst was more active than Cu/TiO2 and TiO2. At 0–50 °C reaction temperature, the activity of TiO2 and Pd/TiO2 increased with an increase of reaction temperature. When the temperature was as high as 70 °C, the reaction rate of TiO2 drop slightly and Pd/TiO2 became less effective. In contrast, Cu/TiO2 was more active at room temperature than the other temperatures. The results indicate that the photocatalytic activi...

Journal of Applied Polymer Science

ACS Omega

The calcium phosphate spherical material with a hierarchical structure has been used as a bone im... more The calcium phosphate spherical material with a hierarchical structure has been used as a bone implantation material. To improve the properties of the implant material, the compositions of calcium phosphate, silicon, and titanium are crucial. The presence of silicon on the surface of the phosphate−calcium material accelerates the bonding of the implant with the bone (osseointegration). The aim of this work was to develop a sol−gel method to prepare spherical calcium-phosphate@TiO 2 −SiO 2 biomaterials for bone implantation. The CaO@TiO 2 −SiO 2 biomaterial with a core− shell structure was synthesized by the sol−gel method. The biological properties of the materials were studied with a simulated body fluid (SBF). The sample had a spherical shape. The sample exhibited bioactive properties because an increase in the content of calcium and phosphorus ions in the shell and the presence of precipitated ions from the solution were detected on the surface. The TiO 2 −SiO 2 framework was uniformly fixed on the CaO core. Heat treatment of the hybrid mesostructure led to the formation of mesoporous materials with a specific regular structure in the nanometer size in the shell, which is necessary for the fixation of biological cells when the sample is introduced into the biological medium. The formation of a calcium−phosphate layer on the materials and the release of soluble silicon and calcium ions into the SBF are the key factors for the rapid connection of these materials with tissue. The results demonstrate that the CaO@TiO 2 −SiO 2 biomaterial with a core−shell structure is a good candidate for bone implantation.

Crystals

YPO4:Eu, YVO4:Eu, and YVPO4:Eu based phosphors with various Eu(III) activator contents and phosph... more YPO4:Eu, YVO4:Eu, and YVPO4:Eu based phosphors with various Eu(III) activator contents and phosphate-vanadate ratios were synthesized by the self-propagating high-temperature synthesis method. The samples were characterized by scanning electron microscopy, nitrogen sorption, acid-base indicators and photoluminescence. The particle surface features with a finely dispersed structure comprising all the involved elements. The pore structure and the specific surface areas of the samples were different depending on the compositions of the samples. The most finely dispersed sample was YVO4:Eu samples. The specific surface areas of the YPO4:Eu samples were 10 to 15 times greater than those of vanadate samples. The phosphors samples had a slightly basic (YVO4:Eu, YVPO4:Eu) or slightly acidic (YPO4:Eu) properties of the surface with different contents of Lewis and Brönsted sites. The differences in the compositions and acid-base state resulted in the difference in the intensity and brightness...

Journal of Chemical Technology & Biotechnology

Journal of Porous Materials

Applied Catalysis

The synthesis of hydrocarbons from synthesis gas was studied over a series of zeolites (HX, HY an... more The synthesis of hydrocarbons from synthesis gas was studied over a series of zeolites (HX, HY and CuX) mixed with Ru/TiOP catalysts at 1 atm, 473-573 K, H,:CO = 1 and GHSV = 1800 h-l. A Ru/TiO,-Si02 catalyst was used for comparision. It was found that the acidity of the zeolites could modify the catalytic properties by (1) increasing CO conversion, (2) increasing C, hydrocarbon formation, (3) increasing the selectivites for olefins and (4) increasing isobutene formation. The results can be interpreted with a bifunctional mechanism of the catalysts. In the addition, the rate-determining step is shifted from the reactions taking place over the Fischer-Tropsch catalysts to diffusion of C, hydrocarbons into the zeolites.

Powder Technology, 2004

Ultrafine barium titanate (BaTiO 3) particles with cubic phase were synthesized by a hydrothermal... more Ultrafine barium titanate (BaTiO 3) particles with cubic phase were synthesized by a hydrothermal conversion reaction. The direct thermal hydrolysis of titanium tetrachloride with perchloric acid had been used for producing nanosized TiO 2 particles. The size and morphology of the TiO 2 particles were controlled by the molar ratio of acid to water (H/Ti ratio) in the solutions. As the H/Ti ratio is 1, the morphology of TiO 2 particles was distinct elongated particles with the major axis ca. 80 nm and the minor axis ca. 10 nm. These TiO 2 particles were predominated in the rutile phase. These TiO 2 particles were then used as a precursor to prepare BaTiO 3 by the hydrothermal conversion in a barium hydroxide solution. The crystal structure of the BaTiO 3 particles was cubic phase with a lattice constant of 4.072 nm (a-axis). The morphology of the particles was near-spheres with a size distribution of 20-50 nm. The reaction temperature and time did not influence the size and the morphology of BaTiO 3 particles, but the lattice constant of a-axis shrunk slightly and the impurity of BaCO 3 decreased. The Ba/ Ti molar ratio did not influence the morphology and crystal structure, but the mean particle size decreased with increasing the Ba/Ti ratio. The size and morphology of the BaTiO 3 particles were different from those of the precursor TiO 2 particles, indicating a dissolution-precipitation mechanism for the conversion of TiO 2 to BaTiO 3. The particles were cubic phase if the calcination temperature was lower than 900 jC and were converted to tetragonal phase with the tetragonality (c/a) of 1.0105 after calcination at 1150 jC for 2 h in air.

Adsorption Science and Technology, 2000

Many mesoporous materials have been prepared by the surfactant-assisted self-assemble of inorgani... more Many mesoporous materials have been prepared by the surfactant-assisted self-assemble of inorganic precursor. Most of such materials reported to date are amorphous in nature. If precise chemical structure can be build into the precursor, it may be possible to introduce certain crystallinity into the mesoporous framework by the same surfactant-assisted process. This proposal has been tested by preparing SiO2 precursor with certain degree of zeolite structure before the incorporation of surfactant template. A mesoporous material was indeed produced that showed regular structure in nanometer scale by XRD, as well as double 5-ring molecular scale structure of by FTIR. The variation of properties with the preparation procedures will be discussed based on their XRD, ASAP and FTIR measurements.

Studies in Surface Science and Catalysis, 2000

... Selective Hydrogenation of Furfural on Ni-PB Nanometals Shao-Pai Lee and Yu-Wen Chen* Departm... more ... Selective Hydrogenation of Furfural on Ni-PB Nanometals Shao-Pai Lee and Yu-Wen Chen* Department of Chemical Engineering, National Central University, Chung-Li ... D)Ni-PB (1:3:3)** Ni83.9P9.0BT.1 Ni82.sPll.0B6.2 130.5 floss aggregate (E)Ni-PB (1:3"1) NiTa.sP12.1B13 ...

Journal of nanoscience and nanotechnology, 2013

Pd/TiO2 and Pd/CeO2 were reported to be very active to destruct toluene. Combination of TiO2 and ... more Pd/TiO2 and Pd/CeO2 were reported to be very active to destruct toluene. Combination of TiO2 and CeO2 is an interesting candidate to achieve a catalyst with higher activity. In this study, a series of Pd/CeO2-TiO2 catalysts with various Pd loadings were prepared. CeO2-TiO2 was prepared by impregnation of aqueous solution of cerium nitrate into TiO2 support. It was then calcined at 400 degrees C. Pd was loaded by incipient-wetness impregnation method. The Pd loadings in all samples were fixed at 0.5 wt.%. The catalysts were characterized by powder X-ray diffraction, transmission electron microscopy, high resolution transmission electron microscopy, temperature-programmed reduction of hydrogen, and X-ray photoelectron spectroscopy. The catalysts were tested for total oxidation of toluene. The feed concentration of toluene was 8.564 g/m3 (2085 ppm), with GHSV = 10,000 h(-1). Pd particle sizes were 3-5 nm and well-dispersed on the support. CeO2 on TiO2 was easier to reduce than the bulk...

Chinese Journal of Catalysis, 2013

Mo and La have been independently reported to be good promoters of NiB nanocluster in the hydroge... more Mo and La have been independently reported to be good promoters of NiB nanocluster in the hydrogenation of para-chloronitrobenzene (p-CNB). However, a bi-promoter effect of Mo and La in NiB catalysts has not previously been investigated. In this work, a series of La-Mo-doped, nanosized NiB catalysts with different La contents were prepared by chemical reduction and were characterized by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The liquid-phase hydrogenation of p-CNB was carried out in a batch reactor at 333 K, 1.2 MPa H2 pressure and at a spinning rate of 500 r/min. Even doping a small amount of La in NiMoB had a significant effect on its activity and selectivity to p-chloroaniline. The addition of an appropriate amount of La suppressed the growth and long-range order of NiMoB and helped the NiMoB maintain its amorphous state. La was determined to be present in its oxide form and to act as a spacer, preventing NiMoB from sintering and aggregation. However, a high amount of La had an opposite effect, and the optimum ratio of La:Ni was 0.2.

C, 2021

A series of PtRu/carbon black catalysts were prepared by means of deposition-precipitation and re... more A series of PtRu/carbon black catalysts were prepared by means of deposition-precipitation and reduced by various reducing agents. NaBH4, HCHO and NaH2PO2, respectively, were used as the reduction agents. Some of the samples were reduced by various amounts of NaH2PO2 to investigate the effects of P/Pt ratios on the characteristics and activity of the catalyst. These catalysts were characterized by X-ray diffraction and transmission electron microscopy. The components of these catalysts were detected by X-ray fluorescence, X-ray photoelectron microscopy, and extended X-ray absorption of fine structures (EXAFS). The methanol oxidation ability of the catalysts was tested by cyclic voltammetry measurement. The results show that NaH2PO2 could effectively reduce the particle size of PtRu metal. It can suppress the growth of metal particles. In addition, the P/Pt ratio is crucial. The catalyst reduced by NaH2PO2 with a P/Pt ratio of 1.2 had the highest activity among all catalysts. It had ...

Materials, 2021

In this study, high-surface-area carbon black is used to support PtRu. In order to increase the f... more In this study, high-surface-area carbon black is used to support PtRu. In order to increase the functional groups on the surface of carbon black and to have a more homogenous dispersed PtRu metal, the surface of carbon black is functionalized by H2O2. PtRu/carbon black is synthesized by the deposition–precipitation method. NaH2PO2 is used as the reducing agent in preparation. These catalysts are characterized by N2 sorption, temperature-programmed desorption, X-ray diffraction, transmission electron microscope, and X-ray photoelectron spectroscopy. The methanol oxidation ability of the catalyst is tested by cyclic voltammetry measurement. Using H2O2 to modify carbon black can increase the amount of functional groups on the surface, thereby increasing the metal dispersion and decreasing metal particle size. NaH2PO2 as a reducing agent can suppress the growth of metal particles. The best modified carbon black catalyst is the one modified with 30% H2O2. The methanol oxidation activity ...

Catalysis Communications, 2007

Modern Research in Catalysis, 2013

The effects of palladium addition and the reduction methods on Au/TiO 2 were investigated. Pd was... more The effects of palladium addition and the reduction methods on Au/TiO 2 were investigated. Pd was loaded on TiO 2 firstly by incipient-wetness impregnation, Au was then loaded by deposition-precipitation method. The nominal loadings of Au and Pd were 1 wt% and 0.01 wt%. The bimetallic catalysts were reduced by heating at 453 K, by flowing H 2 at 423 K, or by NaBH 4 at 298 K. The catalysts were characterized by ICP, XRD, TEM, HRTEM, TPR and XPS. Hydrogenation of p-chloronitrobenzene was carried out at 1.2 MPa H 2 pressure and 353 K. The results showed that even adding very small amount of Pd could enhance activity and selectivity of p-chloroaniline significantly. Pd and Au formed alloy and Pd could donate partial electron to Au. Pd metal on the surface of alloy could adsorb hydrogen and enhanced the activity. The pretreatment methods did not change particle size significantly, all were below 4 nm. The sample reduced by NaBH 4 could have higher concentration of Au 0 and sustain small Au particle size, resulting in high activity.

OALib, 2014

A series of Ag@TiO 2 catalysts with core-shell structure were successfully synthesized by a sol-g... more A series of Ag@TiO 2 catalysts with core-shell structure were successfully synthesized by a sol-gel method. The samples were prepared by a sol-gel method using silver nitrate, hydrazine, cetyltrimethylammonium bromide and titanium tetra-isopropoxide as the starting materials. The catalysts were characterized by ICP-MS, XRD, TEM, HRTEM and XPS. The results indicated that the silver core was in metallic state and the TiO 2 shell was in anatase state. The size of Ag nanoparticles in core was about 5 and 10 nm, and the shell size of titanium dioxide was 10 and 20 nm. The core was single crystalline Ag nanoparticle and the shell was made up of many TiO 2 nanoparticles. The photocatalytic activity of Ag@TiO 2 was much higher than that of bare TiO 2. Large amounts of hydroxyl groups were present on the surface of TiO 2. The catalysts which were treated by hydrothermal method had the higher lattice oxide percentage and higher photocatalytic activities. The core-shell structure can prevent Ag from aggregation.

Journal of Catalysts, 2013

A series of Au/-TiO2 with various Co/Ti ratios prepared. /TiO2 was prepared by incipient wetness ... more A series of Au/-TiO2 with various Co/Ti ratios prepared. /TiO2 was prepared by incipient wetness impregnation with aqueous solution of cobalt nitrate. Au catalysts were prepared by deposition-precipitation (DP) method at pH 7 and 338 K. The catalysts were characterized by inductively coupled plasma-mass spectrometry, temperature programming reduction, X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The reaction was carried out in a fixed bed reactor with a feed containing 1% CO in air at weight hourly space velocities of 120,000 mL/h g and 180,000 mL/h g. High gold dispersion and narrow particle size distribution were obtained by DP method. The addition of into Au/TiO2 enhanced the activity of CO oxidation significantly. Au/5% -TiO2 had the highest catalyst among all the catalysts. was mainly in the form of nanosize Co3O4 which could stabilize the Au nanoparticles. donated partial electrons...

Modern Research in Catalysis, 2013

A series of Au/CuO x-TiO 2 with various Cu/Ti ratios were prepared. CuO x /TiO 2 was prepared by ... more A series of Au/CuO x-TiO 2 with various Cu/Ti ratios were prepared. CuO x /TiO 2 was prepared by incipient-wetness impregnation with aqueous solution of copper nitrate. Au catalysts were prepared by deposition-precipitation method at pH 7 and 338 K. The catalysts were characterized by inductively-coupled plasma-mass spectrometry, temperature programming reduction, X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The reaction was carried out in a fixed bed reactor with a feed containing 1% CO in air at WHSV of 120,000 mL/h•g. High gold dispersion and narrow size distribution was obtained. The addition of CuO x in Au/TiO 2 enhanced the activity on CO oxidation significantly. CuO x was in amorphous state which could stabilize the Au nanoparticles. Cu was in Cu 1+ state. Cu donated partial electrons to Au. The interactions among Au, Cu 1+ and TiO 2 account for the high catalytic activity for CO oxidation. The significant promotional effect of CuO x on CO oxidation at low temperature was demonstrated.

The Journal of …, 2009

NiO with novel flower-like morphology was prepared by using a two-step, template-and surfactant-f... more NiO with novel flower-like morphology was prepared by using a two-step, template-and surfactant-free, environmentally friendly method. Flower-like NiO was composed of many irregular nanosheets that were assembled together by weak interactions. The as-prepared ...

Catalysts

The aim of this study was to investigate the effects of reaction temperature on the photocatalyti... more The aim of this study was to investigate the effects of reaction temperature on the photocatalytic activity of TiO2 with Pd and Cu cocatalysts. N2 sorption, transmission electron microscopy and high-resolution transmission electron microscopy were used to characterize the specific surface area, pore volume, pore size, morphology and metal distribution of the catalysts. The photocatalytic destruction of methylene blue under UV light irradiation was used to test its activity. The concentration of methylene blue in water was determined by UV-vis spectrophotometer. Pd/TiO2 catalyst was more active than Cu/TiO2 and TiO2. At 0–50 °C reaction temperature, the activity of TiO2 and Pd/TiO2 increased with an increase of reaction temperature. When the temperature was as high as 70 °C, the reaction rate of TiO2 drop slightly and Pd/TiO2 became less effective. In contrast, Cu/TiO2 was more active at room temperature than the other temperatures. The results indicate that the photocatalytic activi...

Journal of Applied Polymer Science

ACS Omega

The calcium phosphate spherical material with a hierarchical structure has been used as a bone im... more The calcium phosphate spherical material with a hierarchical structure has been used as a bone implantation material. To improve the properties of the implant material, the compositions of calcium phosphate, silicon, and titanium are crucial. The presence of silicon on the surface of the phosphate−calcium material accelerates the bonding of the implant with the bone (osseointegration). The aim of this work was to develop a sol−gel method to prepare spherical calcium-phosphate@TiO 2 −SiO 2 biomaterials for bone implantation. The CaO@TiO 2 −SiO 2 biomaterial with a core− shell structure was synthesized by the sol−gel method. The biological properties of the materials were studied with a simulated body fluid (SBF). The sample had a spherical shape. The sample exhibited bioactive properties because an increase in the content of calcium and phosphorus ions in the shell and the presence of precipitated ions from the solution were detected on the surface. The TiO 2 −SiO 2 framework was uniformly fixed on the CaO core. Heat treatment of the hybrid mesostructure led to the formation of mesoporous materials with a specific regular structure in the nanometer size in the shell, which is necessary for the fixation of biological cells when the sample is introduced into the biological medium. The formation of a calcium−phosphate layer on the materials and the release of soluble silicon and calcium ions into the SBF are the key factors for the rapid connection of these materials with tissue. The results demonstrate that the CaO@TiO 2 −SiO 2 biomaterial with a core−shell structure is a good candidate for bone implantation.

Crystals

YPO4:Eu, YVO4:Eu, and YVPO4:Eu based phosphors with various Eu(III) activator contents and phosph... more YPO4:Eu, YVO4:Eu, and YVPO4:Eu based phosphors with various Eu(III) activator contents and phosphate-vanadate ratios were synthesized by the self-propagating high-temperature synthesis method. The samples were characterized by scanning electron microscopy, nitrogen sorption, acid-base indicators and photoluminescence. The particle surface features with a finely dispersed structure comprising all the involved elements. The pore structure and the specific surface areas of the samples were different depending on the compositions of the samples. The most finely dispersed sample was YVO4:Eu samples. The specific surface areas of the YPO4:Eu samples were 10 to 15 times greater than those of vanadate samples. The phosphors samples had a slightly basic (YVO4:Eu, YVPO4:Eu) or slightly acidic (YPO4:Eu) properties of the surface with different contents of Lewis and Brönsted sites. The differences in the compositions and acid-base state resulted in the difference in the intensity and brightness...

Journal of Chemical Technology & Biotechnology

Journal of Porous Materials

Applied Catalysis

The synthesis of hydrocarbons from synthesis gas was studied over a series of zeolites (HX, HY an... more The synthesis of hydrocarbons from synthesis gas was studied over a series of zeolites (HX, HY and CuX) mixed with Ru/TiOP catalysts at 1 atm, 473-573 K, H,:CO = 1 and GHSV = 1800 h-l. A Ru/TiO,-Si02 catalyst was used for comparision. It was found that the acidity of the zeolites could modify the catalytic properties by (1) increasing CO conversion, (2) increasing C, hydrocarbon formation, (3) increasing the selectivites for olefins and (4) increasing isobutene formation. The results can be interpreted with a bifunctional mechanism of the catalysts. In the addition, the rate-determining step is shifted from the reactions taking place over the Fischer-Tropsch catalysts to diffusion of C, hydrocarbons into the zeolites.

Powder Technology, 2004

Ultrafine barium titanate (BaTiO 3) particles with cubic phase were synthesized by a hydrothermal... more Ultrafine barium titanate (BaTiO 3) particles with cubic phase were synthesized by a hydrothermal conversion reaction. The direct thermal hydrolysis of titanium tetrachloride with perchloric acid had been used for producing nanosized TiO 2 particles. The size and morphology of the TiO 2 particles were controlled by the molar ratio of acid to water (H/Ti ratio) in the solutions. As the H/Ti ratio is 1, the morphology of TiO 2 particles was distinct elongated particles with the major axis ca. 80 nm and the minor axis ca. 10 nm. These TiO 2 particles were predominated in the rutile phase. These TiO 2 particles were then used as a precursor to prepare BaTiO 3 by the hydrothermal conversion in a barium hydroxide solution. The crystal structure of the BaTiO 3 particles was cubic phase with a lattice constant of 4.072 nm (a-axis). The morphology of the particles was near-spheres with a size distribution of 20-50 nm. The reaction temperature and time did not influence the size and the morphology of BaTiO 3 particles, but the lattice constant of a-axis shrunk slightly and the impurity of BaCO 3 decreased. The Ba/ Ti molar ratio did not influence the morphology and crystal structure, but the mean particle size decreased with increasing the Ba/Ti ratio. The size and morphology of the BaTiO 3 particles were different from those of the precursor TiO 2 particles, indicating a dissolution-precipitation mechanism for the conversion of TiO 2 to BaTiO 3. The particles were cubic phase if the calcination temperature was lower than 900 jC and were converted to tetragonal phase with the tetragonality (c/a) of 1.0105 after calcination at 1150 jC for 2 h in air.

Adsorption Science and Technology, 2000

Many mesoporous materials have been prepared by the surfactant-assisted self-assemble of inorgani... more Many mesoporous materials have been prepared by the surfactant-assisted self-assemble of inorganic precursor. Most of such materials reported to date are amorphous in nature. If precise chemical structure can be build into the precursor, it may be possible to introduce certain crystallinity into the mesoporous framework by the same surfactant-assisted process. This proposal has been tested by preparing SiO2 precursor with certain degree of zeolite structure before the incorporation of surfactant template. A mesoporous material was indeed produced that showed regular structure in nanometer scale by XRD, as well as double 5-ring molecular scale structure of by FTIR. The variation of properties with the preparation procedures will be discussed based on their XRD, ASAP and FTIR measurements.

Studies in Surface Science and Catalysis, 2000

... Selective Hydrogenation of Furfural on Ni-PB Nanometals Shao-Pai Lee and Yu-Wen Chen* Departm... more ... Selective Hydrogenation of Furfural on Ni-PB Nanometals Shao-Pai Lee and Yu-Wen Chen* Department of Chemical Engineering, National Central University, Chung-Li ... D)Ni-PB (1:3:3)** Ni83.9P9.0BT.1 Ni82.sPll.0B6.2 130.5 floss aggregate (E)Ni-PB (1:3"1) NiTa.sP12.1B13 ...

Journal of nanoscience and nanotechnology, 2013

Pd/TiO2 and Pd/CeO2 were reported to be very active to destruct toluene. Combination of TiO2 and ... more Pd/TiO2 and Pd/CeO2 were reported to be very active to destruct toluene. Combination of TiO2 and CeO2 is an interesting candidate to achieve a catalyst with higher activity. In this study, a series of Pd/CeO2-TiO2 catalysts with various Pd loadings were prepared. CeO2-TiO2 was prepared by impregnation of aqueous solution of cerium nitrate into TiO2 support. It was then calcined at 400 degrees C. Pd was loaded by incipient-wetness impregnation method. The Pd loadings in all samples were fixed at 0.5 wt.%. The catalysts were characterized by powder X-ray diffraction, transmission electron microscopy, high resolution transmission electron microscopy, temperature-programmed reduction of hydrogen, and X-ray photoelectron spectroscopy. The catalysts were tested for total oxidation of toluene. The feed concentration of toluene was 8.564 g/m3 (2085 ppm), with GHSV = 10,000 h(-1). Pd particle sizes were 3-5 nm and well-dispersed on the support. CeO2 on TiO2 was easier to reduce than the bulk...