Papers by Keyword: Hydrogen

Abstract: In recent years, the EU policy identified the hydrogen as one of the main energy vectors to support the power production from renewable sources. Coherently, electrolysis is suitable to convert energy in hydrogen with no carbon emission and high purity level. Among the electrolysis technologies, the anion exchange membrane (AEM) seems to be promising for the performance and the development potential at relatively high cost. In the present work, AEM electrolysers, and their technological bottlenecks, have been investigated, in comparison with other electrolysers’ technology such as alkaline water electrolysis and proton exchange membranes. Major efforts and improvements are investigated about innovative materials design and the corresponding novel approach as main focus of the present review. In particular, this work evaluated new materials design studies, to enhance membrane resistance due to working cycles at temperatures close to 80 °C in alkaline environment, avoiding the employment of toxic and expensive compounds, such as fluorinated polymers. Different strategies have been explored, as tailored membranes could be designed as, for example, the inclusion of inorganic nanoparticles or the employment of not-fluorinated copolymers could improve membranes resistance and limit their environmental impact and cost. The comparison among materials’ membrane is actually limited by differences in the environmental conditions in which tests have been conducted, thereafter, this work aims to derive reliable information useful to improve the AEM cell efficiency among long-term working periods.

Abstract: The growing interest towards hydrogen technologies and their implementation in the hydrocarbon and chemical process industry makes maintenance planning of storage and transport equipment an emerging safety aspect. With respect to high-pressure working equipment, Risk-Based Inspection methodology (RBI) aims at minimizing the risk of loss of containment due to materials’ deterioration mechanisms. This set of procedures focuses on the mechanical integrity of equipment to achieve crucial risk mitigation by means of risk-informed inspection planning and maintenance activities. In addition, hydrogen-induced damages are often generalized or even neglected by the existing RBI standards and recommended practices. On this basis, high-pressure vessels, process piping and storage tanks working in gaseous or liquid hydrogen environments, which are exposed to hydrogen-induced deterioration mechanisms, might be subjected to an inaccurate evaluation of the associated risk and hazards when these RBI standards are applied. For this reason, this work proposes a review of the pipelines steels commonly used for gaseous hydrogen transport to investigate the possible limitations of the standard RBI planning methodologies, when applied to hydrogen technologies. More accurately, the pipeline steels’ susceptibility to hydrogen-induced degradations mechanisms will be discussed to underline assumptions and hypothesis limiting the conventional RBI applicability. Therefore, the overall suitability of standard RBI planning with respect to hydrogen equipment is discussed, highlighting possible relevant gaps as a general result.

Abstract: In addition to silicon carbide (SiC) and gallium nitride (GaN), gallium oxide (Ga₂O₃) is attracting attention as a widegap semiconductor material. Ga₂O₃, unlike SiC and GaN, is not as hard, but has strong cleavage properties, making highly effective mechanical machining difficult. Thus, the processing of Ga₂O₃ by high-speed etching employing atmospheric-pressure plasma was studied. An extremely high removal rate of 60 μm/min was obtained due to basic processing experiments using hydrogen gas instead of toxic and corrosive chlorine gas as the reaction gas.

Abstract: Aluminium-water reaction is one of the most promising ways to produce clean and economical hydrogen. In this study, the effect of the waste Aluminium foil AA1235 thickness on Aluminium-water reaction process was investigated. The thickness of aluminum used are 6.5 m, 11.5 m and 19.5 m. Aluminum foil was cut by size 20 mm x 30 mm in each thickness variation. The 0.4 M NaOH and 0.01 M NaAlO₂ was added as promoter on the process. The initial composition of the aluminum and the dislocations in the aluminum are also considered. The experimental results was evaluated by the mass reduction and shrinking core models. The initial composition of the aluminum and the dislocations in the aluminum are also considered. The experimental results were evaluated by the mass reduction and shrinking core models. The results obtained that aluminum with thinner thickness can be approximated by the 1-dimensional slab shrinking core model. Aluminum with a thicker thickness can be approached with a mass reduction model. It is also found out that smaller thickness has larger dislocation and better effects of NaAlO₂ resulting higher yield of hydrogen production.

Abstract: This research investigated the Hydrogen doping of the single-walled carbon nanotube (HCNT) with encapsulated cellulose, (C₆H₁₀O₅)₂, and provide theoretical predictions on the properties of the resulting complex system. After full structural optimization, two different bond lengths and angles in the HCNT and (C₆H₁₀O₅)₂/HCNT system were calculated. Further, it was found that substitutional H atoms acted as charge acceptors and drove necessary rearrangements in the valence region. The (C₆H₁₀O₅)₂ caused some peaks at the valence band mainly caused by the p orbitals of the oxygen atoms. A bandgap decrease has been observed for the (C₆H₁₀O₅)₂/HCNT system. The results are consistent with the previous works which demonstrated the possibility of band gap engineering in CNTs.

Abstract: In geothermal environment corrosion fatigue lowers the lifetime expectancy of high alloyed steels. Therefore, cathodic protection enhances corrosion resistance although hydrogen is produced during the cathodic reactions under applied potential. Corrosion fatigue of standard duplex stainless steel X2CrNiMoN22-5-3, 1.4462 specimen loaded with hydrogen was investigated in a specifically designed corrosion chamber surrounded by the Northern German Basin electrolyte at 369 K. The reactions of the microstructure associated with hydrogen incorporation lowers the number of cycles to failure of specimen significantly at various stress amplitudes, for example at σ_a = 275 MPa and U_SHE = -36 mV by 80%. Hydrogen enhances crack propagation and early failure due to the degradation of the mechanical properties of the ferritic phase.

Abstract: The susceptibility of advanced high-strength steels (AHSS) to hydrogen embrittlement (HE) limits the broad utilization of these materials for body-in-white (BIW) components. The considerable decrease of both ductility and toughness due to local hydrogen accumulation inside of formed components may cause unpredictable time-delayed failure. In particular deep-drawn and punched AHSS components are prone to hydrogen absorption. This work investigates the influence of plastic deformation on hydrogen absorption of dual phase (DP) steels. For that purpose, tensile samples were machined out of three commercial 1.2 mm-thick DP sheets with ultimate tensile strengths of 626 MPa, 826 MPa and 1096 MPa. Samples were uniaxially pre-strained to 2 %, 5 %, 10 %, 15 % and 20 %. After pre-straining the samples were electrochemically charged with hydrogen, and the actual hydrogen contents were determined using a thermal desorption analyser (TDA). Before and after charging, the hardness of the samples was measured and the uniaxial quasi-static tensile properties were determined. In order to quantify the influence of plastic deformation on HE, slow strain rate tests (SSRT) were performed. The results of the tests were correlated with the fraction of martensite determined for each of the three steels.

Abstract: The effect of Pb small additives on the microstructure and phase composition of palladium-based diffusion membrane-filters was studied in this work. In the present study, we comprehensively investigated the lead-containing palladium alloy by X-ray diffraction using synchrotron radiation and high-resolution scanning electron microscopy. The predisposition of the alloy to the formation of a conditionally homogeneous nanodisperse substructure with small values of micro-deformations is established. The stable preservation of the phase composition during a single hydrogenation is revealed.

Abstract: In this work, the insulating properties of nitride coatings against the hydrogen penetration into semi-finished or finished products made of VT6 titanium alloy during hydrogenation annealing have been studied. It has been established that an increase of the duration of titanium nitride deposition for more than 30 minutes leads to the formation of pores and cracks in the coating and, as a consequence, to a decrease in the «protective» properties of such coating. It is shown that during linear gradient structure creation, the nitride coating effectively “protects” alloy from penetration of up to 0.5 wt%. of hydrogen.

Abstract: The article presents a systematic analysis and simulation of the process of destructive hydrogenation of deasphalted oil. The process of thermoregeneration of spent zeolite and the surface - acid properties of CaA zeolite catalysts are also studied. It has been established that such patterns that allow predicting their influence and to regulate the quality of the hydrogenation obtained on one or another form of the catalyst obtained from the studied factors and catalysts. In addition, the obtained data can be used in the search for the optimal process modes of the process under consideration on the specific form of the catalyst.