Papers by Keyword: Hydrogen Generation

Abstract: The article analyzes the systems for generation, purification, transportation and storing of gaseous hydrogen as the alternative renewable energy source for ensuring of level of ecological safety of power plants with reciprocation internal combustion engines exploitation process. Purpose of the study is to improve the description of the process of purifying gaseous hydrogen from associated impurities during its production, storage and transportation based on the results of mathematical modeling analysis using improved mathematical apparatus based on modified thermodynamic perturbation theory. Problem of the study is the imperfection of the existing mathematical apparatus for describing the processes of purification of gaseous hydrogen as a commercial product and renewable ecological safe energy carrier using sorption metal hydride technologies based on TiMn_1,5. Idea of the study is to develop a list of recommendations and organizational and technical measures for obtaining ultra-high purity gaseous hydrogen in environmental protection technologies by improving the adequacy of the mathematical description of the processes of its sorption-desorption by intermetallic compounds based on TiMn_1,5. Task of the study is to adapt the mathematical apparatus of the modified thermodynamic perturbation theory to describe the process of selective sorption of hydrogen by metal hydrides of the type TiMn_1,5 from gas mixtures obtained during its production, storage and transportation. Object of the study is sorption processes in metal hydride technologies for the purification of gaseous hydrogen as an alternative fuel and a useful commercial product based on TiMn_1,5. Subject of the study is mathematical description of the course of hydrogen sorption processes by intermetallic compounds of the type TiMn_1,5 when purified from gas impurities. Methods of the study are literature analysis, modified thermodynamic perturbation theory, mathematical modeling. Scientific novelty of results of the study is for the first time, an apparatus for mathematically describing the processes of hydrogen sorption by intermetallic compounds of the type has been suggested TiMn_1,5 from gas mixtures during its production, storage and transportation based on the improvement of the modified thermodynamic perturbation theory. Practical value of results of the study is the improved mathematical apparatus and the results of its application which are suitable for developing a list of recommendations and organizational and technical measures for obtaining ultra-high purity gaseous hydrogen as an ecologicale safe renewable fuel in environmental protection technologies both during the times of armed aggression and during the post-war reconstruction of critical infrastructure and economic potential of our country. The main part of the research is devoted to the adaptation of the mathematical apparatus of the modified perturbation theory to describe the sorption processes of the interaction of hydrogen, which is in the state of a gas mixture, and intermetallic compounds of the type TiMn_1,5. It has been shown that based on sorption metal hydride technologies of the type TiMn_1,5 it is possible to achieve ultra-high purity of gaseous hydrogen as a commercial product when using it as an environmentally safe, renewable type of motor fuel. Mathematical modeling of hydrogen sorption by intermetallic compounds, performed on the basis of the mathematical apparatus of the thermodynamic perturbation theory improved in the study and on the example of the intermetallic hydride TiMn_1,5, based on the application of the lattice gas model for metal hydrides. A list of recommendations and organizational and technical measures has been developed for the implementation of this type of environmental protection technologies in the practice of the units of the State Emergency Service of Ukraine, in particular the operation of fire and emergency rescue equipment with internal combustion piston engines, both during armed aggression and during the post-war reconstruction of critical infrastructure and the economic potential of our country and ensuring the fulfillment of the requirements contained in the Order of the State Emergency Service of Ukraine No. 618 (on the main activity) dated September 20, 2013. «On Approval of the Regulations on the Organization of Environmental Support of the State Emergency Service of Ukraine» and in the historical perspective of achieving the sustainable development goals contained in the Decree of the President of Ukraine No. 722/2019 of September 30, 2019 «About the Goals of Sustainable Development of Ukraine for the Period up to 2030».

Abstract: Kinetic studies of the photocatalytic decomposition of cationic dyes MB (Methylene Blue) and RhB (Rhodamine B), and hydrogen generation from a water–methanol mixture were carried out using nanosized particles of anatase and binary composites based on it with 2 wt.% of palladium or cerium. Nanocomposites were synthesized by a chemical method using TTIP (Titanium TetraIsoPropoxide) in the presence of aqueous salt solutions containing doping metals. The paper briefly describes the structure, morphology, and chemical composition of the anatase-based nanoparticles using modern physical-chemical methods. In the presence of TiO₂&Pd particles, the destruction degree of RhB and MB under the UV irradiation during 60 min reached 81.0–85.5%, and in the presence of TiO₂&CeO₂ particles – 95%. The dye destruction process was accompanied by a hypsochromic shift of chromophoric peaks, which indicated the decomposition products formation. The reactions are pseudo-first order, and the rate constants are within 10^-2. Photocatalytic activity for hydrogen generation using UV radiation showed increased activity (H₂ 3519 μmol·g^-1) for TiO₂&2wt.%Pd due to the possible penetration of palladium atoms into the anatase lattice with efficient separation of photogenerated charge carriers in this system.

Abstract: Solar Energy is an everlasting source of energy with minimal carbon footprint. However, due to lack of reliability and consistency it needs to be converted into more reliable and effective means that can be used to provide energy on demand. Hydrogen is a promising carrier and is thus an efficient mean of energy to be converted in, stored and transported. A more direct approach towards harnessing Solar Energy is by photo-aided generation of hydrogen via splitting of water using photolysis. Photocatalytic water splitting is therefore a promising method for future energy security. On the other hand strain sensing is a useful technique to measure medium range loads in trusses or tension rods & can easily replace the existing fragile & expensive semiconductor based sensors. This was done by using a composite of TiO2 /Reduced Graphene Oxide (RGO); TiO2 (anatase) was synthesized via sol-gel process and the main precursor was titanium tetrapropoxide (Ttip). Titania (anatase) characterized by XRD and photo spectrometry while Graphene oxide was synthesized via modified Hummer’s Method. The obtained Reduce Graphene Oxide was dispersed using Sodium Dodecyl Benzene (SDB) and Hydrazine Hydrate. A drastic synergetic effect was found by simply mixing RGO with TiO2 Solution. This not only broadened the photoactivity spectrum of TiO2 from UV region to the more available visible light radiation but also exhibit strain sensing properties and considerable tunable gauge factor. The photocatalytic effect of our composite was tested by coating it over Polycarbonate & then analyzing emitted gas bubbles in a UV radiation chamber while strain sensing was done by coating it on an elastic substrate & applying loads against values of resistance which were measured. This study will also include the reduction of recombination and band gap of TiO2 in order to synchronize it with the available Solar Spectrum thus maximizing solar-to-hydrogen efficiency.

Abstract: Hydride has been introduced into Al-BiCl₃ composite by ball milling. The hydrogen generation performances of Al-BiCl₃-hydride composite have been effectively promoted. Among of them, Al-BiCl₃-Li₃AlH₆ is found to have the best performance of hydrogen yield (1293 mL·g^-1), the conversion efficiency (94.4%) and the max HG rate (2098 mL·g^-1·min^-1) at 25 ^oC. Due to Li₃AlH₆ need to be prepared, the increasing production process is inevitable. For the Al-BiCl₃-LiBH₄ composite, its hydrogen generation performances are measured which hydrogen yield, the conversion efficiency and the max HG rate of were 1103 mL·g^-1, 84.2% and 2068 mL·g^-1·min^-1, respectively at 25 ^oC. Activation energy (Ea) is calculated as 13.39 kJ·mol^-1. The lower Ea indicates that introducing hydride can enhance the reaction activity of the system on the kinetics and then improve the material properties.

Abstract: Several amorphous alloys (Ni-Fe-B) were synthesized using liquid phase reduction method. The influences of molar ratios n(Fe)/n(Fe+Ni) and different temperatures on phase composition, morphology and catalytic activity were investigated. The resulting products were characterized by XRD and TEM methods, and the catalytic activities were also evaluated by way of hydrogen release ability of NaBH₄ hydrolysis. The results show that the products have stable amorphous phase structures. With the increase of n(Fe)/n(Fe+Ni), the crystallizing tendency rises and the agglomeration strengthens. Under the conditions (T=333K, n(Fe)/n(Fe+Ni)=0.5), the as-prepared samples exhibit the highest catalytic activity, and the highest hydrogen generation rate is 1.70 mL/min^-1.

Abstract: Hydrogen is a clean and new energy carrier to generate power and effectively turned out through the gasification of organic material such as coal. The main objective of this manuscript is to present an analysis of the coal gasification for the generation of high-purity hydrogen in a lab-scale fixed-bed downdraft gasifier. Better understanding of the rank, formation, structure, composition and calorific value and method of analysis of the material is crucial for the proper utilization of these resources requires. Traditionally the quality of the Coal samples has been determined by their physical and proximate analysis, such as, bulk density, free swelling index, gross calorific value, sulfur, moisture, fixed carbon, volatile matter and ash content. In this study, coal is partially oxidized and ultimately converts into hydrogen rich syngas (CO and H₂). As well, approximately 220 kg h⁻¹ of coal would be gasified at 673–1073 K and 46.2 atm with the reactor volume 0.27m³ to obtain approximately 3.8×10⁵ kcal h⁻¹ of thermal energy during over 67% syngas generation with the generation of 110kW electrical powers.

Abstract: In this study, the potential usage of PKS as a direct source for hydrogen production is being explored in the presence of bimetallic Fe-Ni/Zeolite β (BEA) catalyst. The catalyst was prepared by co-impregnation method and calcined at temperatures between 500-700 oC to study the effect of calcination temperatures on the gas compositions from steam gasification of PKS. The textural properties and crystalline phase present were characterized using BET and X-Ray Diffraction. The catalysts were tested in steam gasification of PKS in a fixed-bed microreactor at 700 oC using 0.3 g catalyst and 0.9 g PKS. The steam to PKS ratio was 4:1 (vol) while steam to Ar ratio was 1:6 (vol.). The Fe-Ni/BEA catalysts possess lower surface area, higher pore volume and larger pore diameter as compared to the bare BEACalcination temperature is found to contribute to the crystallization of the prepared catalysts where high crystallization of Fe and Ni was observed in Fe-Ni/BEA (700) catalyst with the formation of NiO and NiFe₂O₄ phase. Fe-Ni/BEA (700) shows the highest composition of H₂ gas produced with 76.32 vol% H₂, 18.72 vol% CO₂, 4.96 vol% CO and the absence of CH₄. This shows that the steam gasification of PKS in the presence of Fe-Ni/BEA (700) has a potential to replace the commercial H₂ production via methane reforming process.

Abstract: The photolytic hydrogen generation using sunlight attracts attention as a next generation energy technology. A key of this technology is a selection of materials for the photolysis and SiC is one of the candidate materials for this application. The conversion efficiency from the solar to the hydrogen energy would be affected by the carrier lifetime in SiC. Therefore, in this study, we measured carrier lifetimes in SiC and compared them with photocurrents in electrolytes that is directly correlated to the conversion efficiency.

Abstract: Titania nanotubes (TiO₂ NTs) working electrodes for hydrogen production by photoelectrocatalytic water splitting were synthesized by means of anodization method. The electrolytes were the mixtures of oxalic acid (H₂C₂O₄), ammonium fluoride (NH₄F), and sodium sulphate (VI) (Na₂SO₄) with different pHs. A constant dc power supply at 20 V was used as anodic voltage. The samples were annealed at 450 °C for 2 hrs. Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) were used to characterized TiO₂ NTs microstructure. TiO₂ NTs with diameter of 100 nm were obtained when pH 3 electrolyte consisting of 0.08 M oxalic acid, 0.5 wt% NH₄F, and 1.0 wt% Na₂SO₄ was used. Without external applied potential, the maximum photocurrent density was 2.8 mA/cm² under illumination of 100 mW/cm². Hydrogen was generated at an overall photoconversion efficiency of 3.4 %.

Abstract: In this paper, magnesium hydride was used to react with water to produce the hydrogen gas. Magnesium hydride is the chemical compound MgH2, which contains 7.66% by weight of hydrogen. Although the concept of reacting chemical hydride with water to produce hydrogen is not new, there have been a number of recent published papers which might be employed to power fuel cell devices for portable applications. Under the room temperature, the hydrolytic reaction between magnesium hydride and water to form a thin-layer of magnesium hydroxide on the outer surface impedes water from coming into direct contact with the magnesium hydride. The key to continual removal of the coherent magnesium hydroxide layer by adding a citric acid has the following conclusions. First, using this approach can reach the 6.4wt% of hydrogen. Finally, the cost of producing hydrogen from magnesium hydride-water hydrogen generation approach would cost approximately $15 per kg hydrogen.