Hydrogen storage in nickel doped MCM-41

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

Hydrogen storage in single wall carbon nanotubes produced on iron catalyst

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

Synthesis and characterization of metal loaded mcm-41 zeotypes and their utilization in hydrogen storage

In this study, we investigated the hydrogen storage behavior of MCM-41 that is a mesoporous material with high surface area and uniform pore size, which makes it a good candidate for gas adsorption applications. To improve the hydrogen storage capacity of MCM-41, the samples were loaded with Pd and Ni that are known with their affinities to hydrogen. MCM-41 samples were synthesized by microwave irradiation and metals were loaded before the samples were calcined. The effect of loading metals (Pd and Ni) and microwave power (90 and 120 W) to the structure of MCM-41 were investigated. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetric analyzer, BET analyzer, and X-ray photoelectron spectroscopy. The hydrogen storage capacities of the samples were measured by Intelligent Gravimetric Analyzer (IGA) at 298 K and up to 10 bar. The kinetics behavior and computational modeling of the hydrogen storage of MCM-41 were also investigated. It was seen that loading Pd and Ni to MCM-41 enhanced the hydrogen uptake of the material. The highest adsorption capacities were measured as 0.98, 1.34, 1.74 for Pd-Ni, Ni, and Pd loaded MCM-41, respectively. The textural properties of the samples were affected by the microwave power used during the synthesis. The kinetics investigation and the review of the experimental results with the findings of the computational studies were novel contributions to the literature

Hydrogen adsorption of carbon nanotubes grown on different catalysts

Single wall carbon nanotubes (SWCNTs) were synthesized by catalytic chemical vapor deposition of C2H2 at 800°C for 60 min. Catalysts were prepared by impregnation of transition metals (Fe, Co, Ni, V and bimetallic mixture of Fe-Co) on MgO powder substrate with a metal to MgO ratio of 5:100. After the synthesis, the samples were purified by liquid phase oxidation method with 1.5M HNO3 for 30 min at 210°C. The samples were characterized by thermal gravimetric analysis, scanning electron microscopy, X-ray diffraction and Raman spectroscopy. The hydrogen storage capacities of purified SWCNTs were investigated by volumetric method. It was found that the hydrogen uptake was in the range of 2.76-5.25 wt% at cryogenic temperature and 100 bar pressure. The maximum capacity was obtained with purified SWCNTs produced on Fe catalyst whereas purified SWCNTs grown on Fe-Co catalyst had the minimum hydrogen uptake

Investigation of the effect of reaction time, weight ratio and type of catalyst on the yield of multi wall carbon nanotubes via chemical vapor deposition of acetylene

The synthesis of multi wall carbon nanotubes (MWCNTs) was studied using catalytic chemical vapor deposition of acetylene at 500°C for 30 and 60 min. Catalysts were prepared by impregnating Fe, Co, Ni, V, and bimetallic mixture of Fe-Co on MgO with a weight ratio of 1:100, 5:100 and 10:100. The effects of the reaction time, the type, and the weight ratio of the catalysts on the carbon yield of MWCNTs were investigated. Experimental results showed that the 10:100 weight ratio of Fe-Co:MgO had the highest carbon yield (81.97%) and the MWCNT to amorphous carbon ratio (100.6) whereas 10:100 V:MgO had the lowest carbon yield (8.44%). Statistical analyses indicated that increasing weight ratio enhanced the carbon efficiencies of Fe, Co, Fe-Co and Ni catalyst; moreover, increasing the reaction time had a positive effect on the carbon efficiencies of Fe and V catalysts

Effect of loading bimetallic mixture of Ni and Pd on hydrogen storage capacity of MCM-41

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 N-2 adsorption and it was observed that they had large surface area around 938-1369 m(2)/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

Synthesis of palladium incorporated MCM-41 via microwave irradiation and investigation of its hydrogen storage properties

MCM-41 is a mesoporous silica material with high surface area and uniform pore size, which makes it a good candidate for gas adsorption applications. To improve the hydrogen storage capacity of the pure MCM-41, the samples were loaded with Pd that is known with its affinity to hydrogen. MCM-41 samples were synthesized by microwave irradiation and Pd was loaded before the samples were calcined. In this study, the effect of loading Pd and microwave power (90 & 120 W) to the structure of MCM-41 was investigated. The surface areas and density functional theory (DFT) pore diameters of the samples were in the range of 1073-1515 m(2)/g and 3.54-3.78 nm, respectively. The hydrogen storage capacities of the samples were measured by Intelligent Gravimetric Analyzer (IGA) at 298 K and up to 10 bar pressure. The hydrogen uptake of the samples were affected by the microwave power used for the synthesis and the Pd content. The highest hydrogen uptake was 1.74 wt% for 10:100 Pd: MCM-41 (120 W)

Mesoporous MCM-41 material for hydrogen storage: a short review

Decreasing supply of fossil fuels and concerns about environmental issues makes hydrogen a good alternative to fossil fuel sources as it is an environmentally friendly energy carrier. However, the storage of hydrogen is the main challenge to its effective use. For the utilization of hydrogen, the development of safe, effective and high capacity storage media is needed. MCM-41 that is most commonly used in catalytic applications has been also considered for hydrogen storage due to its high surface area, uniform pore size and good adsorption properties. There are a number of researches in which MCM-41 is now also considered as hydrogen storage media with a maximum reported hydrogen uptake of 2.01 wt%. However, there is not any review specifically on the hydrogen storage of MCM-41. Therefore, the present review highlights the recent studies on the use of MCM-41 as hydrogen storage media as well as its synthesis conditions and the effect of loading metal on the storage capacity