Palladium Membrane Research Articles

ВІДНОВЛЕННЯ ПАЛАДІЄВИХ МЕМБРАН ПІСЛЯ КОНТАКТУ З ВОД-НЕМ ДЛЯ ВОДНЕВО-КИСНЕВИХ ПАЛИВНИХ ЕЛЕМЕНТІВ

Annotation. Studying the deformations of palladium membranes under the influence of hydrogen, which is a relevant issue for hydrogen energy and the nuclear industry. The mechanisms of palladium membrane shape change due to hydrogen penetration and the formation of temporary gradient alloys such as α-PdHn are consid-ered. Experiments were conducted using a hydrogen-vacuum installation, where the processes of membrane satu-ration and degassing were studied at temperatures from 100°C to 360°C and hydrogen pressures from 0.01 MPa to 2.5 MPa. It was established that the change in the shape of the membrane occurs in two stages: first, a rapid bending of the membrane is observed, and then a gradual return to the initial state. It was established that the maximum change in the shape of the membrane, which occurs at a constant temperature, depends on the diffu-sion coefficient and the equilibrium solubility of hydrogen in palladium. However, when the temperature chang-es, the diffusion coefficient of hydrogen in palladium and the equilibrium concentration of hydrogen in palladi-um also change, which affects the temperature dependence of the final shape change of the membrane. This fact makes it possible to effectively determine the time of hydrogen penetration into the membrane, control the change in shape and adjust the operating modes of the fuel cell. Special attention is paid to the use of palladium alloys with copper and silver to increase the resistance of membranes to the influence of hydrogen. It is shown that such alloys have better mechanical characteristics and a longer service life at high temperatures. The effect of degassing on the restoration of membranes after contact with hydrogen was studied, the main factors affecting the efficiency of this process were determined. The results of the work confirm the need for further research on increasing the resistance of palladium membranes to deformations, as well as the development of new materials and technologies to improve their operational characteristics

Powder bed fusion of solid and permeable Crofer 22 APU parts for applications in chemical process engineering

AbstractAdditive manufacturing of metals has attracted significant attention across various industries. However, its adoption in certain chemical and energy sectors remains constrained by the absence of optimized alloys tailored for high temperatures and corrosive environments. This study explores the laser-based powder bed fusion processing of Crofer 22 APU, a high-temperature, corrosion-resistant alloy ideal for applications such as methane steam reforming reactors, high-temperature fuel cells, and palladium membrane supports. Systematic optimization of laser parameters including laser power, hatch distance, point distance, and building angles was conducted for both dense and porous objects. Dense parts achieved a relative density of 0.9999 and surface roughness of Sa= 41.27±1.48 on a 45$$^\circ$$ ∘ overhang. Porous samples showed a porosity range of 28.655.5% and surface roughness Sa 22.2 $$\upmu$$ μ m to 45.9 $$\upmu$$ μ m as hatch distance increased from 0.12 mm to 0.16 mm. Additionally, an 8YSZ coating applied via screen printing demonstrated the impact of hatch distance and laser power on surface quality. The combination of additive manufacturing of Crofer 22 APU and screen printing of 8YSZ simplifies the preparation of metallic supports for Pd-based membranes, reducing fabrication time and cost by shortening the number of preparation steps. This technique offers a promising approach for scaling up membranes and membrane reactors.

Electrolytic Conversion of Nitro Compounds into Amines in a Membrane Reactor.

Aromatic and aliphatic amines are key intermediates in the synthesis of pharmaceuticals, dyes, and agrochemicals. These amines are often sourced from nitro compounds. The hydrogenation of nitro compounds into amines requires harsh reaction conditions (e.g., high pressures and high temperatures) or additives that are usually toxic. Here we demonstrate the electrochemically-driven hydrogenation of nitro compounds into amines in the hydrogenation compartment of a membrane reactor. The hydrogen is sourced from water in an adjacent electrolysis compartment separated by a hydrogen-permeable palladium membrane. Modifications of the palladium membrane with catalyst coatings enabled a wide range of commercially relevant nitro compounds to be hydrogenated into amines, without any additives, at ambient pressure and room temperature. This membrane reactor also enables nitro hydrogenation at high reagent concentrations with high functional group tolerance.

Comprehensive assessment of the effectiveness of the hydrogen production and transportation system

Based on the energy development strategy of Russia until 2035, the article substantiates the prospect for the development of nuclear energy, according to which nuclear plants are planned to be forced to unload in the range of up to 50% of the rated power while participating in the regulation of daily unevenness of the electrical load. In addition, nuclear power plants will be involved in primary frequency regulation, which is also associated with the unloading mode of operation of nuclear power plants. All these circumstances force us to look for ways to provide nuclear power plants with base load. Along with pumped storage power plants, the article considers an alternative option in the form of using a hydrogen complex based on the electrolysis production of hydrogen, which satisfies the concept of its carbon-free production. The article presents the global dynamics of the introduction of electrolyzers, and in addition to the increase in the share of electrolysis hydrogen produced at nuclear power plants. The hydrogen complex in this case is a means of providing the nuclear power plant with a base load, which involves the consumption of unclaimed electricity at cost. This allows hydrogen to be produced at a competitive price compared to individual producers on the market. The resulting hydrogen is in great demand as a useful product in a number of industries. The article provides examples of hydrogen consumption in various areas of consumption depending on purity, taking into account the requirements of GOST. A number of consumer industries use hydrogen of a special degree of purity, i.e., more than 99.999% vol. In this regard, additional hydrogen purification on palladium membranes was taken into account. A comprehensive assessment of the efficiency of the hydrogen production system was carried out, taking into account its additional purification and delivery to the consumer in various ways, mastered and in demand in world practice. A comparison has been made of the methods of delivering hydrogen to the consumer in comparison with the production of hydrogen by electrolysis at the point of consumption. A comparison was made using the criterion of net present value for the option of third-party consumers who do not have their own hydrogen production.

Optimizing power output in direct formic acid fuel cells using palladium film mediation: experimental and DFT studies

Low-temperature hydrogen production from environmentally friendly liquid fuels such as methanol, ethanol, and formic acid for miniature fuel cells used in powering portable electronic devices is attracting reasonable attention. In this study, we present the findings from the decomposition of formic acid and subsequent power generation within a microfluid fuel cell. The fuel cell system was engineered to incorporate a palladium membrane at the anode and a modified carbon Torray paper at the cathode. To assess fuel cell performance, we employed chronopotentiometry and cyclic voltammetric electro­chemical techniques. This simple fuel cell could achieve a current peak of 3.17 µW by utilizing 2.50 M HCOOH solution and 2.26 µW with 0.1 M solution, all at room temperature. Finally, to provide a deeper understanding of the reactivity and HCOOH decomposition pathways on various palladium surfaces, we conducted density functional theory (DFT) studies. Our DFT investigations revealed that the Pd(111) surface exhibited more negative adsorption energy compared to other surfaces, suggesting its propensity for a more isomeric crystal morphology. This research underscores the promising potential of low-temperature hydrogen production using safe liquid fuels in microfuel cell applications for portable electronic devices.

Modeling of hydrogen separation through Pd membrane with vacuum pressure using Taguchi and machine learning methods

The performance of hydrogen purification using palladium (Pd) membrane is analyzed by Taguchi and machine learning (ML) methods. Three system factors are considered: the feed gas mixture composition (i.e., H2, CO2, and H2O), retentate-side total pressure, and vacuum pressure. The Taguchi method designs the experimental cases based on the constructed orthogonal array. In addition, the hydrogen flux is investigated by the analyses of variance (ANOVA) and artificial neural networks (ANN) methods. The results show that the effects of the considered factors on the hydrogen permeation performance can be ranked as feed gas mixture composition > retentate-side total pressure > vacuum pressure. Both the retentate-side pressure and vacuum pressure present a positive effect on hydrogen flux. The average relative error of hydrogen flux between the experimental results and predictions by ANN is 2.1%, which proves that the ANN method is an effective technique for predicting the hydrogen flux through the Pd membrane. The ML classification test is then performed for hydrogen purity by three machine learning methods: decision tree (DT), support vector machine (SVM), and ensemble method. Among the various classification models, the Quadratic SVM model exhibits a relatively high average training accuracy but shows overfitting. However, the bagged model of the ensemble method can achieve an impressive training accuracy of 91.4% and a prediction accuracy of 85.7%.

Selection and Production of a Suitable Support for Palladium Membranes

The present work focuses on establishing anactual manufacturing strategy that is suitable for the viableproduction of a substrate support for a palladiummembrane; one that will lower production costs and beutilised to gain a competitive edge within the industry.Porous stainless steel supports for palladium membraneswere produced using various types of stainless steel powdersand methods. Observations indicate that SS powder 410Ltype Chengdu Huarui with particle sizes 1-5 μm, sintered inthe HPT induction furnace at temperatures between 930-950°C for a period of 8 minutes, in the presence of argonflow and vacuum, creates a first-class Pd membranesubstrate. Notwithstanding that this result is the mosteconomical method. The results of the study were based onthe: roughness test, first bubble point test, and scanningelectron microscope (SEM). The Chengdu Huarui powdertype 410 L – 1-5 μm, which achieved the best results,produced a roughness test result of Ra 0.614 μm, and abubble point pore size is 1.992 μm.

Analysis of vacuum operation on hydrogen separation from H2/H2O mixture via Pd membrane using Taguchi method, response surface methodology, and multivariate adaptive regression splines

The influence of vacuum pressure applied on H2 separation from a palladium membrane is explored in this study. Three factors with three levels are considered, including the membrane chamber temperature with levels 320 °C, 350 °C, and 380 °C; the retentate-side total pressure with levels 1, 2, and 3 atm; and the permeation-side vacuum pressure with levels 0, 25, and 50 kPa. The Taguchi, response surface methodology (RSM), and multivariate adaptive regression splines (MARS) methods are employed to analyze the effects of the three parameters on hydrogen separation and predict their optimal combination. The retentate-side total pressure exhibits the highest impact on H2 permeation, following the permeation-side vacuum pressure and then the membrane chamber temperature. The maximum H2 flux is 0.226 mol∙s−1∙m−2, with H2 recovery of 91 % obtained at the optimal conditions with a temperature of 380 °C, a total pressure of 3 atm, and a vacuum pressure of 50 kPa. The improvement in H2 flux reaches 21.6 % compared with the case without the imposed vacuum pressure at the same temperature and total pressure. This result shows the imposed vacuum pressure is an efficient way to enhance H2 permeation. The maximum relative errors between the experimental data and the predictions from the Taguchi, RSM, and MARS methods are 6.74 %, 3.37 %, and 8.08 %, respectively. The RSM method presents higher accuracy than Taguchi and MARS, perhaps due to a more precise analysis of the interaction terms. The smaller amount of input data and ignoring the temperature effect in MARS could be the reason for the lower accuracy. Nevertheless, the MARS method still demonstrates acceptable results. The cost of the Taguchi method is lower than that of the RSM method since it requires fewer experimental cases. In a word, the choice of the prediction method depends on the desired accuracy and the experimental cost.

Enhanced ammonia-cracking process via induction heating for green hydrogen: A comprehensive energy, exergy, economic, and environmental (4E) analysis

Ammonia (NH3) is gaining attention as a hydrogen carrier due to its high H2 storage capacity and ease of liquefaction at ambient temperatures. The conventional method of ammonia decomposition is thermal cracking through fossil fuel combustion, resulting in significant carbon dioxide (CO2) emissions. Therefore, developing an eco-friendly and highly efficient ammonia decomposition process is important. This study proposed four high-efficiency processes without carbon emissions by improving the induction-heating-based ammonia decomposition process designed in a previous study. The four proposed processes were designed to utilize the H2 discarded as off-gas of the PSA unit in the existing induction-heating-based ammonia decomposition process. The proposed processes incorporate various unit components, including a proton exchange membrane fuel cell (PEMFC), solid oxide fuel cell (SOFC), burner, and palladium (Pd) membrane. These units were integrated with the PSA outlet to achieve enhanced thermodynamic efficiency compared with the conventional process without carbon emissions. Energy, exergy, economic, and environmental analyses were conducted to assess the feasibility of each case. Thermodynamic analysis revealed that integrating the Pd membrane yields the highest thermal (78.29 %) and exergy (64.02 %) efficiencies. Integrating a PEMFC exhibits the lowest levelized cost of H2 (6.93 USD/kg H2). Finally, When the four proposed processes are operated with renewable energy, clean hydrogen can be produced at 2.45 to 3.21 kgCO2/kgH2 emission levels. The enhanced processes presented in this study can serve as a blueprint for achieving carbon-free green H2 production at on-site H2 refueling stations.

Electrochemical hydrogen pump based on proton exchange membrane for rapid separation of hydrogen and helium

The separation and purification of hydrogen play an essential role in the field of new energy. In addition, it has great significance and economic value in recovering hydrogen isotope gas from plasma ash discharge gas faced by nuclear fusion reactors. Here, we studied the rapid separation of hydrogen and helium by electrochemical hydrogen pump (EHP), a new hydrogen separation and purification method. In the experiment of the hydrogen-helium separation, the recovery rate of hydrogen can reach 97.4%, and the proportion of hydrogen can reach 99.99%. Furthermore, the effects of catalyst layer structure, membrane materials and working conditions for its performance were analyzed. This experiment found that proton conduction in the catalyst layer and proton exchange membrane became the speed-control step of the process. Moreover, efficient catalyst layer design and membrane materials with high proton conductivity are beneficial to improve EHP's performance further. This study could guide further enhancing the hydrogen-helium separation rate in EHP. It aims to promote the development of hydrogen separation and purification of EHP, making it an efficient method of hydrogen-helium separation instead of palladium membrane.

Prospects of membrane catalysis in hydrogen energetics. Mini review

Hydrogen energetics is undoubtedly highly relevant today as it not only allows solving the issue of energy production from a renewable water source but can also prevent the formation of greenhouse gases. They say that any new idea is a well forgotten old one. The paper is dedicated to an excellent but still unimplemented work of Sainte-Claire Deville who managed to obtain hydrogen from water vapor using membrane technology. He used a clay pipe as a membrane which selectively permeated hydrogen. This process occurred with heating up to 950 °C. Sainte-Claire Deville managed to obtain only a mixture of hydrogen and oxygen in a ratio of 4:1 and then to clean the product from oxygen using chemical reactions. Modern membrane catalysts based on palladium or its alloys are selectively permeable only for hydrogen. This means that the membrane catalysis method with palladium membranes could allow to realize of hermal water disassociation more effectively and solve the issues of hydrogen energetics using only renewable raw materials. The history of hydrogen discovery and methods of its production was also studied in this review. Different methods of energy production were analyzed, including mineral resources, wind turbines, solar panels, hydroenergetics, electrolysis, and nuclear power, and a forecast was presented based on them. The review should be considered as an invitation to further discussions regarding this highly relevant and important topic

Electrocatalytic Hydrogenation Using Palladium Membrane Reactors.

Hydrogenation is a crucial chemical process employed in a myriad of industries, often facilitated by metals such as Pd, Pt, and Ni as catalysts. Traditional thermocatalytic hydrogenation usually necessitates high temperature and elevated pressure, making the process energy intensive. Electrocatalytic hydrogenation offers an alternative but suffers from issues such as competing H2 evolution, electrolyte separation, and limited solvent selection. This Perspective introduces the evolution and advantages of the electrocatalytic Pd membrane reactor (ePMR) as a solution to these challenges. ePMR utilizes a Pd membrane to physically separate the electrochemical chamber from the hydrogenation chamber, permitting the use of water as the hydrogen source and eliminating the need for H2 gas. This setup allows for greater control over reaction conditions, such as solvent and electrolyte selection, while mitigating issues such as low Faradaic efficiency and complex product separation. Several representative hydrogenation reactions (e.g., hydrogenation of C=C, C≡C, C=O, C≡N, and O=O bonds) achieved via ePMR over the past 30 years were concisely discussed to highlight the unique advantages of ePMR. Promising research directions along with the advancement of ePMR for more challenging hydrogenation reactions are also proposed. Finally, we provide a prospect for future development of this distinctive hydrogenation strategy using hydrogen-permeable membrane electrodes.

Fabrication of a novel palladium membrane sensor for its determination in environmental and biological samples

A novel sensitive, specific, and reversible optical sensor for the palladium(ii) ion was created by impregnating an agarose membrane with 4-(2-amino-3-hydroxypyridine-4-ylazo)1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one (AHDDO).

ПЕРСПЕКТИВИ РОЗВИТКУ ВОДНЕВОЇ ЕНЕРГЕТИКИ З МОЖЛИВІСТЮ ВІДНОВЛЕННЯ МЕМБРАН ДЛЯ ПАЛИВНИХ ЕЛЕМЕНТІВ ПІСЛЯ КОНТАКТУ З ВОДНЕМ

The prospects for the development of hydrogen energy and the influence of temperature on the change in the shape of the membrane for fuel cells in contact with hydrogen have been studied. It has been confirmed that the change in the shape of the plate from the α-PdHn gradient alloy develops in two stages. The experimental regularities of the change in the shape of the palladium membrane during operation in a hydrogen environment were investigated. It was determined that upon contact with hydrogen, a temporary gradient material "metal-hydrogen" is formed in the membrane, which causes the development of hydrogen concentration stresses, and the maximum change in the shape of the membrane, which occurs at a constant temperature, depends on the diffusion coefficient and the equilibrium solubility of hydrogen in palladium. However, when the temperature changes, the diffusion coefficient of hydrogen in palladium and the equilibrium concentration of hydrogen in palladium also change, which affects the temperature dependence of the final shape change of the membrane. This fact makes it possible to effectively plan and determine the time of hydrogen penetration into the membrane, control the change of shape and adjust the operating modes of the fuel cell. It is the equilibrium solubility of hydrogen in palladium and its diffusion coefficient when the temperature changes in the main that determine the maximum and final change in the shape of the membrane, and the temperature determines the fluctuation of the change in the shape of the membrane when the temperature of the hydrogen flow entering the chamber changes. Thus, the complete return of the membrane to its initial state at increased temperature clearly indicates the implementation of a coherent membrane bending mechanism. Upon completion of hydrogen saturation by the coherent mechanism under the conditions of reaching equilibrium with the gas phase, the original palladium membrane turns out to be transformed into a membrane of the equilibrium alloy α-PdHnо, which inherits the initial state of a pure palladium membrane. Therefore, to model the hydrogen penetration process in the fuel cell, it is necessary to know the gas flow rate, membrane permeability and gas temperature, as well as the diagram of the fuel cell where these processes take place. At the same time, scientists still hope for the future development of hydrogen energy, despite the existing difficulties. This requires additional research and development of new technologies to remove obstacles to the transition to hydrogen as a primary energy source

Fabrication of thin(∼2 μm) pure Ni and Pd–Ni alloy composite membranes by the organic-inorganic activation method for hydrogen separation

In this study, we have reported a new strategy to prepare metal/ceramic membranes that can be used as an alternative to conventional high-cost palladium membranes. For the first time, a uniform Ni layer was deposited using the organic-inorganic activation method via the ELP technique. Although, alloying Pd–Ni resulted in a defect-free thin membrane layer (2 μm). The H2 permeation flux of the composite membrane was 1.43 × 10−2 mol m−2 s−1 at 450 °C and TMP of 100 kPa with infinite H2/N2 selectivity. Stage cut effect as a function of transmembrane pressure (TMP) was assessed in binary mixtures at 450 °C. The prepared composite membrane indicated perfect long-time permeance stability for 145 h at 450 °C and TMP of 100–300 kPa. The results showed that solution-diffusion is the dominant mechanism in the hydrogen transport through the composite membranes.

Determining flux-limiting mechanism of hydrogen permeation through palladium membrane by n value

Pd film has been endowed with the hydrogen selective permeation capability and widely used for hydrogen separation via a series of complex processes. Clarifying the exact relationship between permeating mechanism and hydrogen pressure exponent (n) is of great significance to optimize the purification performance, adequate exploration toward which is nevertheless insufficient. In this work, Pd membrane-based hydrogen permeation was divided into seven steps according to the “dissociation-diffusion” principle. The effect of each step on permeation flux with and without considering external mass transfer process was quantified by mathematical and physical models, in which the relationship between n value and the flux-limiting mechanism was deeply analyzed. The calculation suggested that desorption-limiting mechanism acting as leading role would result in n value to be 0, while external mass transfer dominating the permeation would make n value to be 1. When n value was between 0 and 0.5, desorption and diffusion processes would impose combined impact on the permeation (ignoring external mass transfer) and desorption might have more weight as n approaching to 0. On the other hand, taking external mass transfer into account, desorption-limiting and external mass transfer-limiting mechanism would work together as 0 < n < 1. The closer n approaching to 1, the more significant of external mass transfer mechanism. In addition, the influences of Pd film thickness, ΔP variation and mass transfer coefficient on n value were also elucidated systematically.

Adhesion/Decohesion Processes on the Surface of Palladium Membranes

Adhesion/Decohesion Processes on the Surface of Palladium Membranes

Techno-economic Analysis and Optimization of Intensified, Large-Scale Hydrogen Production with Membrane Reactors.

Steam methane reforming (SMR) currently supplies 76% of the world's hydrogen (H2) demand, totaling ∼70 million tonnes per year. Developments in H2 production technologies are required to meet the rising demand for cleaner, less costly H2. Therefore, palladium membrane reactors (Pd-MR) have received significant attention for their ability to increase the efficiency of traditional SMR. This study performs novel economic analyses and constrained, nonlinear optimizations on an intensified SMR process with a Pd-MR. The optimization extends beyond the membrane's operation to present process set points for both the conventional and intensified H2 processes. Despite increased compressor and membrane capital costs along with electric utility costs, the SMR-MR design offers reductions in the natural gas usage and annual costs. Economic comparisons between each plant show Pd membrane costs greater than $25 000/m2 are required to break even with the conventional design for membrane lifetimes of 1-3 years. Based on the optimized SMR-MR process, this study concludes with sensitivity analyses on the design, operational, and cost parameters for the intensified SMR-MR process. Overall, with further developments of Pd membranes for increased stability and lifetime, the proposed SMR-MR design is thus profitable and suitable for intensification of H2 production.

Highlighting of the impact of periodic operations on the performance of methanol steam reforming process for pure hydrogen generation

In this paper, we focus to highlighting the positive role of periodic operation which can be played for performance improvement of a hydrogen separator reactor integrating a palladium membrane. For this subject, a mathematical approach describing the pure hydrogen production and its pumping during methanol steam reforming process is developed to simulate the effect of the reactor inlet feed and of sweeping gas on reactor performance. The main findings show that the reactor responses exhibit a periodic phenomenon. So, in order to achieve a yield improvement higher than that obtained under the steady state conditions, it is necessary to intensify the process by using a periodic operation. Therefore, when the reactor is simultaneously forced by running the feed composition in the reaction side and by the sweeping gas in the permeate side using a symmetric square function, the magnitude of improvement of methanol conversion and pure hydrogen recovery are higher than that achieved at steady state operation. This is due to the dual effect synergistic, which is could be brought by the potential periodic mode of the inputs coupling.

H2 permeance and surface characterization of a thin (2 μm) Pd-Ni composite membrane prepared by electroless plating

The high cost of palladium membranes limits their widespread use in industrial applications. We report a novel strategy for the preparation of economic hydrogen separation membranes. In this study, a Pd88-Ni12 composite membrane was prepared with a considerable nickel content (>10 wt%) for the first time using the organic–inorganic activation method in the ELP approach. The H2 permeance of the Pd88-Ni12 composite membrane was 4.34 × 10-7 mol m−2 s−1 Pa−1 at 500 °C with infinite selectivity (H2/N2). The membrane exhibited suitable performance when exposed to binary mixtures under various operating conditions. At 500 °C and 100 kPa, with the same concentration of impurity gases, the H2 permeance of the Pd88-Ni12 composite membrane was 3.33 × 10 -7 mol m−2 s−1 Pa−1 for the H2-Ar mixture, 3.12 × 10 -7 mol m−2 s−1 Pa−1 for the H2-N2 mixture, 2.56 × 10 -7 mol m−2 s−1 Pa−1 for the H2-CO2 mixture, and 2.54 × 10 -7 mol m−2 s−1 Pa−1 for the H2-CO mixture. The effect of operating parameters and the amount of impurity concentration in the gas feed on the stage cut in binary gas mixtures was investigated. Increasing operating temperature and pressure enhanced the stage cut for all mixtures while increasing the impurity concentration in the gas feed led to a decrease in the stage cut, independent of operating conditions. The Pd88-Ni12 composite membrane indicated suitable long-time permeance stability for 150 h at a transmembrane pressure range of 100–300 kPa and 500 °C under an H2/N2 gas atmosphere. Finally, the cost investigation demonstrated that the Pd88-Ni12 composite membrane had a 38 % lower specific cost than the pure palladium composite membrane.