Papers by ezgi dundar tekkaya
ABSTRACT MCM-41 was produced by microwave irradiation, which allows high yield, improved product ... more ABSTRACT MCM-41 was produced by microwave irradiation, which allows high yield, improved product purity, increased reaction rate and crystallization. As transition metals enhance the hydrogen uptake, Pd and Ni were loaded on MCM-41 to increase the hydrogen storage capacity of the structure. The surface areas of the samples were measured by N2 adsorption and it was observed that they had large surface area around 938-1369 m2/g. The successful incorporation of metals into the structure was confirmed by characterization using X-ray diffraction and X-ray photoelectron spectroscopy. The hydrogen adsorption capacities of the samples were measured by the Intelligent Gravimetric Analyzer at room temperature and up to 10 bar pressure. The hydrogen storage capacity of MCM-41 was improved by increasing content of bimetallic mixture of Pd and Ni. The maximum hydrogen uptake was obtained as 0.98 wt% with 10:100 Pd-Ni:MCM-41.
Abstract—Carbon nanotubes (CNTs) with their high mechanical, electrical, thermal and chemical pro... more Abstract—Carbon nanotubes (CNTs) with their high mechanical, electrical, thermal and chemical properties are regarded as promising materials for many different potential applications. Having unique properties they can be used in a wide range of fields such as ...
Hydrogen as an energy carrier is one of the best environmentally friendly alternatives to fossil ... more Hydrogen as an energy carrier is one of the best environmentally friendly alternatives to fossil fuel sources. The potential use of hydrogen results with increasing demand to hydrogen production and storage. Recent studies show that materials having high surface area, large pore size and high affinity to hydrogen have high hydrogen storage capacity. MCM-41 is silica based material having such properties and its hydrogen sorption properties can be improved by doping transition metals to the structure. Ni was chosen for this purpose as it is known with its hydrogen affinity. In this study, different amounts of Ni doped in MCM-41 that was produced by microwave heating to examine hydrogen storage capacity of Ni doped MCM-41 systems. The morphology and structure of the material was characterized by scanning electron microscope and X-ray diffraction analysis. Thermal stability of MCM-41 was examined by thermogravimetric analysis and it was seen that MCM-41s are hydrothermally stable. Surface area, pore size and adsorption capacity of MCM-41 were measured by Brunauer-Emmett-Teller (BET) method. It was observed that the material had large surface area around 1000 m 2 /g and roughly 2 nm pore size. It was found materials have uniform pore structure with hexagonal well-ordered arrangement. BET surface area, pore volume and pore diameters decreased as the metal loading increased. The hydrogen adsorption capacity measurements were achieved by the Intelligent Gravimetric Analyzer at room temperature and up to 10 bar pressure. It was observed that the hydrogen storage capacity of MCM-41 is strongly affected by metal doping.
In this study, the effect of time, temperature and the weight ratio of the catalyst on the carbon... more In this study, the effect of time, temperature and the weight ratio of the catalyst on the carbon efficiency and the structure of carbon nanotubes (CNTs) were investigated. CNTs were synthesized by catalytic chemical vapor deposition of acetylene on Co-MgO catalyst at 500 and 800°C. Catalysts were prepared by impregnation of Co on MgO powder substrate with Co to MgO ratio of 1:100, 5:100 and 10:100. The duration of syntheses was selected as 30 and 60 minutes for all temperatures and metal to substrate ratios. The morphology and structure of the CNTs were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis. Thermal gravimetric analysis (TGA), and Raman spectroscopy were used for further characterization.
Templated nanoporous carbon structures were synthesized using MCM-41 which is a silica based mate... more Templated nanoporous carbon structures were synthesized using MCM-41 which is a silica based material with ordered structure, high surface area, and large pore size. Therefore, it was considered as a good candidate to be used as template for the synthesis of nanoporous carbon structures. MCM-41 was synthesized via microwave heating method which is both energy and time efficient. After the MCM-41 was filter washed and calcined, it was then stirred in furfuryl alcohol. Following this process, the synthesis of nanoporous carbon structures was achieved under the flow of Ar gas at high temperatures. The morphology and structure of the MCM-41 and the nanoporous carbon material were characterized by scanning electron microscope and X-ray diffraction analysis. Surface area, pore size and adsorption capacity were measured by Brunauer-Emmett-Teller (BET) method.
International Journal of Hydrogen Energy, Jun 29, 2015
ABSTRACT
44th World Chemistry Congress, Research Triangle Park, NC, USA: IUPAC (International Union of Pure and Applied Chemistry), 2013
Hydrogen as an energy carrier is one of the best environmentally friendly alternatives to fossil ... more Hydrogen as an energy carrier is one of the best environmentally friendly alternatives to fossil fuel sources. The potential use of hydrogen results with increasing demand to hydrogen production and storage. Recent studies show that materials having high surface area, large pore size and high affinity to hydrogen have high hydrogen storage capacity. MCM-41 is silica based material having such properties and its hydrogen sorption properties can be improved by doping transition metals to the structure. Ni was chosen for this purpose as it is known with its hydrogen affinity. In this study, different amounts of Ni doped in MCM-41 that was produced by microwave heating to examine hydrogen storage capacity of Ni doped MCM-41 systems. The morphology and structure of the material was characterized by scanning electron microscope and X-ray diffraction analysis. Thermal stability of MCM-41 was examined by thermogravimetric analysis and it was seen that MCM-41s are hydrothermally stable. Surface area, pore size and adsorption capacity of MCM-41 were measured by Brunauer-Emmett-Teller (BET) method. It was observed that the material had large surface area around 1000 m2/g and roughly 2 nm pore size. It was found materials have uniform pore structure with hexagonal well-ordered arrangement. BET surface area, pore volume and pore diameters decreased as the metal loading increased. The hydrogen adsorption capacity measurements were achieved by the Intelligent Gravimetric Analyzer at room temperature and up to 10 bar pressure. It was observed that the hydrogen storage capacity of MCM-41 is strongly affected by metal doping.
44th World Chemistry Congress, Research Triangle Park, NC, USA: IUPAC (International Union of Pure and Applied Chemistry) , 2013
Hydrogen is a promising clean energy alternative to conventional energy sources. Hence, increasin... more Hydrogen is a promising clean energy alternative to conventional energy sources. Hence, increasing demand on hydrogen as energy carrier enhances studies in hydrogen storage. Hydrogen should be safely and efficiently stored in order to overcome existing barriers in hydrogen usage. Single wall carbon nanotube (SWCNT) is an eligible material for hydrogen storage. In this study, SWCNTs were produced by catalytic chemical vapor deposition (CCVD) of acetylene (C2H2) on MgO powder substrate impregnated with Fe. Catalysts were prepared with Fe to MgO ratio of 5:100 using iron nitrate (Fe(NO3)3•9H2O) solution as Fe source. SWCNTs were synthesized at 800°C for 60 minutes. Nitric acid (HNO3), was used for purification of synthesized SWCNT. The aim of the research was to investigate hydrogen storage capacity of as produced and purified SWCNTs synthesized on Fe-MgO catalyst. The morphology and structure of the SWCNTs were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis. Thermal gravimetric analysis (TGA), and Raman spectroscopy were used for further characterization. Hydrogen storage capacities of SWCNTs were measured by high pressure volumetric analyzer using volumetric method at the cryogenic temperature and gas pressure up to 90 bar. It was found that the hydrogen adsorption capacities of these materials were around 1.9 and 5.3 wt% for as produced and purified SWCNTs respectively. With the fact that DOE target for 2015 is 5.5 wt%, it was seen that SWCNTs produced on Fe-MgO catalyst have good potential as hydrogen storage material.
World Academy of Science and Technology
Carbon nanotubes (CNTs) with their high mechanical, electrical, thermal and chemical properties a... more Carbon nanotubes (CNTs) with their high mechanical, electrical, thermal and chemical properties are regarded as promising materials for many different potential applications. Having unique properties they can be used in a wide range of fields such as electronic devices, electrodes, drug delivery systems, hydrogen storage, textile etc. Catalytic chemical vapor deposition (CCVD) is a common method for CNT production especially for mass production. Catalysts impregnated on a suitable substrate are important for production with chemical vapor deposition (CVD) method. Iron catalyst and MgO substrate is one of most common catalyst-substrate combination used for CNT. In this study, CNTs were produced by CCVD of acetylene (C2H2) on magnesium oxide (MgO) powder substrate impregnated by iron nitrate (Fe(NO3)3•9H2O) solution. The CNT synthesis conditions were as follows: at synthesis temperatures of 500 and 800°C multiwall and single wall CNTs were produced respectively. Iron (Fe) catalysts were prepared by with Fe:MgO ratio of 1:100, 5:100 and 10:100. The duration of syntheses were 30 and 60 minutes for all temperatures and catalyst percentages. The synthesized materials were characterized by thermal gravimetric analysis (TGA), transmission electron microscopy (TEM) and Raman spectroscopy.
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Papers by ezgi dundar tekkaya