Hydrogen-based Economy Research Articles

Visualising coke-induced degradation of catalysts used for CO2-reforming of methane with X-ray nano-computed tomography

The switch from a carbon-based to a hydrogen-based economy requires environmentally friendly methods for hydrogen production. CO2-reforming of methane promises to be a greener alternative to steam-methane reforming, which accounts for the majority of hydrogen production today. For this dry process to become industrially competitive, challenges such as catalyst deactivation and degradation through coke formation must be better understood and ultimately overcome. While bulk characterisation methods provide a wealth of useful information about the carbon formed during coking, spatially resolved techniques are required to understand the type and extent of degradation of supported catalyst particles themselves under coking conditions. Here, lab-based X-ray nano-computed tomography, in conjunction with a range of complementary techniques, is utilised to understand the effects of the nickel-to-cobalt ratio on the degradation of individual supported catalyst particles. Findings suggest that a bimetallic system greatly outperforms monometallic catalysts, with the ratio between nickel and cobalt having a significant impact on the type and quantity of the carbon formed and on the extent of supported catalyst breakdown.

Polyimide-derived carbon molecular sieve membranes for high-efficient hydrogen purification: The development of a novel phthalide-containing polyimide precursor

Hydrogen-based economy has been considered as a potential solution for energy security and sustainability in the future. And the ever-increasing demand for high-purity hydrogen (H2) provides an urgent force for the H2 purification technologies. Herein, a novel polyimide (BATPPP-6FDA) with rigid and contorted structure was synthesized and used as a precursor to fabricate the carbon molecular sieve membranes (CMSMs) for H2 purification. The structural changes from precursor to CMS were detected and the H2 separation performance of the membranes was optimized by the pyrolysis temperature. The CMSM pyrolyzed at 550 °C exhibited the highest H2 permeability of 10054.1 Barrer and moderate H2 permselectivity due to its highly disordered and turbostratic carbon structure originated from the generally decomposition of thermally labile -CF3 groups and the lactone rings of phthalide structure in the early stages (<550 °C) of pyrolysis. As the pyrolysis temperature raised, the H2 permeability of the derived CMSM decreased, and the H2 permselectivity enhanced greatly. The CMSM pyrolyzed at 800 °C demonstrated a high H2 permeability of 2622.4 Barrer and superior selectivity with H2/N2 of 524.48, H2/CH4 of 1248.76 and H2/CO2 of 7.51, respectively, which was attributed to the low densification of carbon structure resulting from the rigid and contorted structure of the BATPPP-6FDA precursor. The excellent H2 separation performance showed a great potential in hydrogen purification application.

Identification of the Catalytically Dominant Iron Environment in Iron- and Nitrogen-Doped Carbon Catalysts for the Oxygen Reduction Reaction.

For large-scale utilization of fuel cells in a future hydrogen-based energy economy, affordable and environmentally benign catalysts are needed. Pyrolytically obtained metal- and nitrogen-doped carbon (MNC) catalysts are key contenders for this task. Their systematic improvement requires detailed knowledge of the active site composition and degradation mechanisms. In FeNC catalysts, the active site is an iron ion coordinated by nitrogen atoms embedded in an extended graphene sheet. Herein, we build an active site model from in situ and operando 57Fe Mössbauer spectroscopy and quantum chemistry. A Mössbauer signal newly emerging under operando conditions, D4, is correlated with the loss of other Mössbauer signatures (D2, D3a, D3b), implying a direct structural correspondence. Pyrrolic N-coordination, i.e., FeN4C12, is found as a spectroscopically and thermodynamically consistent model for the entire catalytic cycle, in contrast to pyridinic nitrogen coordination. These findings thus overcome the previously conflicting structural assignments for the active site and, moreover, identify and structurally assign a previously unknown intermediate in the oxygen reduction reaction at FeNC catalysts.

Review on recent progress and reactor set-ups for hydrogen production from formic acid decomposition

Hydrogen is a clean and efficient energy carrier, and a hydrogen-based economy is an alternative solution for sustainability. The present work reviews the recent progress for hydrogen's production from various technologies including the generation from fossil fuels, from biomass through biological and thermochemical processes and from water splitting. Although hydrogen is a zero-emission energy when it is used, its cleanness depends on the production pathway that preceded. Hydrogen's storage and transportation has been costly and an unsafe procedure; formic acid (FA; CH2O2), on the other hand, can be generated, transported, and decomposed easily to hydrogen. Formic acid is generated from the hydrogenation of atmospheric carbon dioxide (CO2) and can easily be provided with energy portable devices, vehicles, and other applications. In addition, the most widely known homogeneous and heterogeneous catalysts and reactors for the formic acid reaction are presented. Different types of reactors like, fixed-bed reactors (FBRs), batch reactors, continuously stirred tank reactors (CSTRs) and microreactors were assessed for their performance and reaction's efficiency during formic acid’s decomposition.

NIR-Driven Photocatalytic Hydrogen Production by Silane- and Tertiary Amine-Bound Plasmonic Gold Nanoprisms.

Near-infrared (NIR) photon-driven H2 production from water is regarded as one of the best routes for establishing a sustainable hydrogen-based energy economy. Here, we have developed a gold nanoprism-based photocatalytic assembly, rationally capped with an amine and a silane ligand pair, which exhibited an excellent H2 production rate (146 μL mg-1 h-1) in neutral water while achieving an absolute incident photon-to-hydrogen conversion efficiency of 0.53%. An array of spectroscopic and microscopic experiments unravel that the amine ligand scavenges the hot hole while the silane aids the H2 production via hydrolysis during the photocatalysis on the plasmon surface. This photocatalytic H2 production reactivity can be retained for multiple cycles following the replenishment of amine and silane. Hence, this photocatalytic assembly can set up the template for a large-scale NIR-driven H2 production unit.

Analysis on the sustainability of different low CO2 emission Hydrogen production technologies for transition towards a ‘zero emission’ economy

Abstract World primary energy consumption reached 14,2 mil. tons of oil equivalent. More than 81.7% of this energy was generated from fossil fuels as primary energy source while 74.5% of the electrical energy was generated from fossil fuels. Energy transition towards zero impact from CO2 emission requires a major shift in the energy mix of the primary sources, decarbonization of the electricity generation, and the use of Hydrogen as the alternative low CO2 emission solution for the high temperature industrial process. Low CO2 Hydrogen could be produced using the conventional technologies (steam methane reform i.e.) with Carbon Capture and Storage, from renewable energy sources through water electrolysis or from biogas / biomass. At this moment none of the low CO2 Hydrogen technologies is competitive, as natural gas-based Hydrogen is around 1.5 EUR/kg while renewable based Hydrogen is in the range of 2.5-5.5 EUR/kg. From the sustainability point of view, besides the production cost issue, the whole life cycle emissions need to be considered. The main goal of this article is to assess different low CO2 emission Hydrogen production technologies by analyzing the CO2 emission along the value chain, together with a sensitive analysis on the main cost drivers, evaluating the impact on upstream and downstream economic sectors, based on case study methodology. This article provides the basis for selecting the most sustainable technology, the prerequisites for an energy transition towards a hydrogen-based economy and highlights the critical links between a Low CO2 Hydrogen transition strategy and other energy strategies. The results suggest that access to low-cost renewable electricity will be the most important factor in driving the production cost down, a decentralized onsite production will further reduce the losses and wind based renewable energy is having the lowest CO2 emission across the entire life cycle.

Assessment of a Stand-alone Hybrid PV-Hydrogen Based Electric Vehicle Charging Station Model Using HOMER

Amongst all introduced renewable resources, hydrogen is one of the most encouraging contenders for meeting energy demands. Hydrogen is the most eco-friendly fuel. Hydrogen is a clean and effective energy carrier, and a hydrogen-based economy is extensively considered as a practical solution for energy security and sustainability in the future. Due to its richness and diverse production resources, hydrogen, is becoming an increasingly possible clean and green alternative for energy storage and transportation. As the existing demand for energy soars, hydrogen has grown into the most important source. This article introduces a techno-economic assessment of a novel stand-alone hybrid PV-hydrogen energy-based charging station in Jamshoro, Sindh, Pakistan, to meet daily charging demand for plug-in Electric Vehicles (EV). The proposed design is modelled and simulated using HOMER software to investigate the conceptual system. The hybrid PV-hydrogen-battery energy system was witnessed to be more cost-effective than the PV-hydrogen energy system, with a unit cost of electricity of 0.379 Rs/kWh versus 0.432 Rs/kWh for the PV-hydrogen energy system. With a daily load demand of 1750 kWh/day, the simulation results showed that total electricity production consists of power generated by solar PV (89.4%) and fuel-cells (10.6%). These outcomes indicate that a renewable-energy-powered EV charging station is cost-effective for the proposed site.

Water Splitting by MnOx/Na2CO3 Reversible Redox Reactions

Thermal water splitting by redox reactants could contribute to a hydrogen-based energy economy. The authors previously assessed and classified these thermo-chemical water splitting redox reactions. The Mn3O4/MnO/NaMnO2 multi-step redox cycles were demonstrated to have high potential. The present research experimentally investigated the MnOx/Na2CO3 redox water splitting system both in an electric furnace and in a concentrated solar furnace at 775 and 825 °C, respectively, using 10 to 250 g of redox reactants. The characteristics of all reactants were determined by particle size distribution, porosity, XRD and SEM. With milled particle and grain sizes below 1 µm, the reactants offer a large surface area for the heterogeneous gas/solid reaction. Up to 10 complete cycles (oxidation/reduction) were assessed in the electric furnace. After 10 cycles, an equilibrium yield appeared to be reached. The milled Mn3O4/Na2CO3 cycle showed an efficiency of 78% at 825 °C. After 10 redox cycles, the efficiency was still close to 60%. At 775 °C, the milled MnO/Na2CO3 cycles showed an 80% conversion during cycle 1, which decreased to 77% after cycle 10. Other reactant compounds achieved a significantly lower conversion yield. In the solar furnace, the highest conversion (&gt;95%) was obtained with the Mn3O4/Na2CO3 system at 775 °C. A final assessment of the process economics revealed that at least 30 to 40 cycles would be needed to produce H2 at the price of 4 €/kg H2. To meet competitive prices below 2 €/kg H2, over 80 cycles should be achieved. The experimental and economic results stress the importance of improving the reverse cycles of the redox system.

Elucidation of Structure-Activity Relations in Proton Electroreduction at Pd Surfaces: Theoretical and Experimental Study.

The structure-activity relationship is a cornerstone topic in catalysis, which lays the foundation for the design and functionalization of catalytic materials. Of particular interest is the catalysis of the hydrogen evolution reaction (HER) by palladium (Pd), which is envisioned to play a major role in realizing a hydrogen-based economy. Interestingly, experimentalists observed excess heat generation in such systems, which became known as the debated "cold fusion" phenomenon. Despite the considerable attention on this report, more fundamental knowledge, such as the impact of the formation of bulk Pd hydrides on the nature of active sites and the HER activity, remains largely unexplored. In this work, classical electrochemical experiments performed on model Pd(hkl) surfaces, "noise" electrochemical scanning tunneling microscopy (n-EC-STM), and density functional theory are combined to elucidate the nature of active sites for the HER. Results reveal an activity trend following Pd(111) > Pd(110) > Pd(100) and that the formation of subsurface hydride layers causes morphological changes and strain, which affect the HER activity and the nature of active sites. These findings provide significant insights into the role of subsurface hydride formation on the structure-activity relations toward the design of efficient Pd-based nanocatalysts for the HER.

Electrocatalytic layers for hydrogen evolution reaction based on nickel phosphides: cost-effective fabrication and XPS characterization

The development of efficient electrocatalysts based on Pt-free materials is a crucial step for the maturation of competitive water splitting technologies able to sustain the upcoming hydrogen-based economy. In this context, the present work optimizes a codeposition/annealing methodology to produce electrocatalytic layers for the hydrogen evolution reaction (HER) based on one of the most promising alternatives to Pt-based catalysts: nickel phosphides. A nickel–phosphorus solid solution is codeposited with red phosphorus microparticles and the obtained composites are annealed to promote interdiffusion and reaction between nickel and phosphorus. The experimentation carried out demonstrates that the properties of the final phosphide layers depend on the conditions employed in both the codeposition step and the annealing step. It is fundamental to evaluate and optimize the NiP/P codeposition process, and it is also important to understand the influence of annealing time and temperature on the microstructure and HER performance of the layers obtained. X-ray photoelectron spectroscopy (XPS) is employed to evaluate the phase composition at the surface, highlighting the presence of a top layer characterized by a Ni2P/Ni12P5 ratio significantly lower than the value found in the bulk of the coating. Annealed NiP/P layers are tested for HER in 0.5 M sulphuric acid solution. The tests demonstrate a clear correlation between the Ni2P/Ni12P5 ratio on the surface and the overpotential for HER. Coherently, when the outer Ni12P5-rich layer is mechanically removed, lower overpotentials are observed (169.5 mV vs. RHE for 10 mA cm−2).

Enhancement of hydrogen evolution reaction kinetics in alkaline media by fast galvanic displacement of nickel with rhodium – From smooth surfaces to electrodeposited nickel foams

Energy-efficient hydrogen production is one of the key factors for advancing hydrogen-based economy. Alkaline water electrolysis is the main route for the production of high-purity hydrogen, but further improvements of hydrogen evolution reaction (HER) catalysts are still needed. Industrial alkaline electrolysis relies on Ni-based catalysts, and here we describe a drastic improvement of HER activity of Ni in alkaline media using several model catalysts for HER, obtained upon nickel surface modification in the aqueous solution of rhodium salts, where a spontaneous deposition of rhodium takes place, based on the chemical displacement reaction 3Ni + 2Rh3+ = 3Ni2+ + 2Rh. In the case of smooth Ni-poly electrodes, HER activity surpasses the activity of Pt-poly after just 30 s of exchange with Rh. SEM analysis showed that Rh is uniformly distributed, and that surface roughness changes are lower than 10%, which is in agreement with the electrochemical measurements. Furthermore, XPS analysis has shown effective incorporation of Rh in the surface, while DFT calculations suggest that hydrogen binding is significantly weakened on the Rh-modified Ni surfaces. Such tuning of the hydrogen binding energy is seen as the main factor governing HER activity improvements. The same galvanic displacement protocols were employed for nickel foam electrodes and electrodeposited Ni on Ti mesh. In both cases, somewhat longer Rh exchange times are needed to obtain superior activities than for the smooth Ni surface, but within 10 min. HER overpotentials corresponding to −10 mA cm−2 for nickel foam and electrodeposited Ni electrodes, after modification with Rh, amounted to only −0.07 and −0.09 V, respectively. Thus, it is suggested that a fast spontaneous displacement of Ni with Rh could effectively boost HER in alkaline media with minor cost penalties with regards to energy saving in the electrolysis process.

Solidified Hydrogen Storage (Solid-HyStore) via Clathrate Hydrates

• A comprehensive review on hydrate based hydrogen (H 2 ) storage is presented. • State of the art for various H 2 -containing hydrate systems are evaluated. • Multiple cage occupancy by H 2 and the tuning effect are discussed systematically. • Challenges, limitations, and future directions for the technology are outlined. • Solid-HyStore technology is recommended for stationary storage of hydrogen. With non-renewable fossil fuels depleting rapidly, hydrogen as a clean energy source producing no pollutants or greenhouse gas emissions upon combustion is bound to play a leading role in the future energy landscape. Among the pertinent challenges in establishing a hydrogen-based economy is developing an energy dense hydrogen storage technology with easy recovery of the stored gas. Clathrate hydrates enabling the innovative solidified storage of hydrogen molecules at moderate temperature and pressure conditions carve a niche for safe, long-term, stationary hydrogen storage. This review focuses on the current state of the art for solidified hydrogen storage (Solid-HyStore) via clathrate hydrates. The properties and performances of various H 2 -containing hydrate systems are evaluated and summarized comprehensively. Multiple cage occupancy by H 2 molecules and the tuning effect as the controversial issues in hydrogen hydrate research are elucidated. Finally, the challenges, limitations, and future opportunities for hydrate-based hydrogen storage are identified.

Hydrogen Recovery from Coke Oven Gas. Comparative Analysis of Technical Alternatives.

The recovery of energy and valuable compounds from exhaust gases in the iron and steel industry deserves special attention due to the large power consumption and CO2 emissions of the sector. In this sense, the hydrogen content of coke oven gas (COG) has positioned it as a promising source toward a hydrogen-based economy which could lead to economic and environmental benefits in the iron and steel industry. COG is presently used for heating purposes in coke batteries or furnaces, while in high production rate periods, surplus COG is burnt in flares and discharged into the atmosphere. Thus, the recovery of the valuable compounds of surplus COG, with a special focus on hydrogen, will increase the efficiency in the iron and steel industry compared to the conventional thermal use of COG. Different routes have been explored for the recovery of hydrogen from COG so far: i) separation/purification processes with pressure swing adsorption or membrane technology, ii) conversion routes that provide additional hydrogen from the chemical transformation of the methane contained in COG, and iii) direct use of COG as fuel for internal combustion engines or gas turbines with the aim of power generation. In this study, the strengths and bottlenecks of the main hydrogen recovery routes from COG are reviewed and discussed.

Hydrogenation and Dehydrogenation of Liquid Organic Hydrogen Carriers: A New Opportunity for Carbon-Based Catalysts

The development of a hydrogen-based economy is the perfect nexus between the need of discontinuing the use of fossil fuels (trying to mitigate climate change), the development of a system based on renewable energy (with the use of hydrogen allowing us to buffer the discontinuities produced in this generation) and the achievement of a local-based robust energy supply system [...]

Japan–EU Cooperation in the Development of Hydrogen-Based Economy

Goal – the paper aims to identify the main areas and motives for Japan–EU cooperation in the development of a hydrogen-based economy. Research methodology – text analysis of governmental documents, institutional reports, companies’ websites, and articles in the specialized press. Score/results – the example of several Japanese companies shows that Japan–EU cooperation has been intensifying, mostly in hydrogen-based mobility in Europe, natural gas transformation and supply in Japan, and renewable hydrogen generation in the EU and Japan. Japanese companies seek new markets and competition to advance and popularize their technologies. The ability to comply with the EU environmental regulations makes them a significant player in global efforts to accelerate GHG emissions reduction. Originality/value – the research on international cooperation in hydrogen is scarce but crucial. The development of a hydrogen-based economy will change both economic and geopolitical dynamics, which is especially important in the face of the economic consequences of Russia’s invasion of Ukraine.

Hydrogen supply chain and production technology

Hydrogen is forecasted as an energy solution for the future thanks to its advantages of cleanliness, abundance and high energy conversion efficiency. The paper briefly introduces the hydrogen supply chain, hydrogen production technologies prevailing or expected in the future, as well as challenges that need to be addressed for a successful transition to a hydrogen-based economy.

Petroleum Sector-Driven Roadmap for Future Hydrogen Economy

In the climate change mitigation context based on the blue hydrogen concept, a narrative frame is presented in this paper to build the argument for solving the energy trilemma, which is the possibility of job loss and stranded asset accumulation with a sustainable energy solution in gas- and oil-rich regions, especially for the Persian Gulf region. To this aim, scientific evidence and multidimensional feasibility analysis have been employed for making the narrative around hydrogen clear in public and policy discourse so that choices towards acceleration of efforts can begin for paving the way for the future hydrogen economy and society. This can come from natural gas and petroleum-related skills, technologies, experience, and infrastructure. In this way, we present results using multidimensional feasibility analysis through STEEP and give examples of oil- and gas-producing countries to lead the transition action along the line of hydrogen-based economy in order to make quick moves towards cost effectiveness and sustainability through international cooperation. Lastly, this article presents a viewpoint for some regional geopolitical cooperation building but needs a more full-scale assessment.

Numerical Investigation of Unsteady Combustor Turbine Interaction for Flexible Power Generation

AbstractWith the growing importance of regenerative power generation and especially of a hydrogen-based economy, the full potential of gas turbines of the smaller output class (&amp;lt;10 MW) can be ideally exploited to provide peak coverage of the energy need whilst stabilizing the electric grids in the mid- and low-voltage range. Such machines can be typically started in a relatively short time (similarly to aero engines) and are capable, at the same time, of delivering dispatchable power-on-demand. A safe, stable and profitable operation under highly unsteady conditions poses renewed challenges for an optimal thermal management (especially in the HP stages) as well as control and surveillance of the machines. The understanding and hence predictability of the propagation of the temperature inhomogeneities originating at the combustor outlet remains hence a primary objective of current research, as persistent distortion patterns could be adopted at the turbine exhaust as diagnostic indications of a malfunction of the combustor, for example. In the present study, low-frequency disturbances introduced by a periodic load variation have been simulated and superimposed to the inhomogeneous, unsteady flow entering a three-stage, high-pressure industrial gas turbine fed by a can-type combustion chamber comprising six silo-burners. The effects of the unsteadiness realized at the combustor exit have been investigated by means of Detached Eddy Simulations, whereby a density-based solution approach with detailed thermodynamics has been employed. The periodic disturbances at the turbine inlet have been obtained by means of an artificially generated, unsteady field, resulting from a two-dimensional snapshot of the flow field at the combustor exit. Also, a combustor failure has been mimicked by reducing (respectively increasing) the mean temperature in some of the turbine inlet regions corresponding to the outlet of two burners. The propagation and amplitude changes of temperature fluctuations have been analyzed in the frequency domain. Tracking of the temperature fluctuations' maxima at the lowest frequencies revealed characteristic migration patterns indicating that the corresponding fluctuations persist with a non-negligible amplitude up to the last rows. A distinct footprint could also be observed at the same locations when a combustor failure was simulated, showing that, in principle, the early detection of combustor failures is indeed possible.

Efficient Screening of Bi–Metallic Electrocatalysts for Glycerol Valorization

Glycerol is a byproduct of biodiesel production and, as such, it is of limited economic value. By means of electrooxidation, glycerol can be used as a feedstock for scalable hydrogen production, in addition to conversion to value-added products. The development of novel and efficient catalytic electrode materials for the anodic side of the reaction is a key towards a hydrogen-based energy economy. In the present study, a computational screening protocol combining DFT, scaling relations, and microkinetic modeling allows for a rational selection of novel catalysts that can deliver efficient glycerol electrooxidation, low cost of production, and environmental sustainability. Activity and chemical selectivity towards hydrogen production on pure metal catalysts is discussed in terms of volcano-shaped plots. We find that the selectivity in the glycerol oxidation reaction is influenced by a different energy landscape when in the presence of water and best classified by a comparison of OH and CH bond-breaking barriers. In addition, we screened 3570 bi-metallic catalysts in the AB (L10) and A3B (L12) ordered structures for activity, stability, price, and toxicity. By filtering based on the criteria for toxicity, resistance to oxidation, miscibility, and price, we have identified 5 L10 structured catalysts (AgPd, AuPd, PtSb, CuPt, and AgPt) and 20 L12 catalysts (Ga3Ta, In3Ta, Ir3W, Ir3Mo, Cu3Pt, Ir3Ta, Ir3Re, Pd3Bi, Pd3Cu, Pd3W, Pd3Co, Pd3Sn, Pd3Mo, Pd3Ag, Pd3Ga, Pd3Ta, Au3Ru, Pd3In, Au3Ir, and Pd3Au) that are all predicted to show high activity. We also identify an additional 37 L10 and 92 L12 structured electrocatalysts with an anticipated medium-high activity.

Catalytic Hydrogen Combustion for Domestic and Safety Applications: A Critical Review of Catalyst Materials and Technologies

Spatial heating and cooking account for a significant fraction of global domestic energy consumption. It is therefore likely that hydrogen combustion will form part of a hydrogen-based energy economy. Catalytic hydrogen combustion (CHC) is considered a promising technology for this purpose. CHC is an exothermic reaction, with water as the only by-product. Compared to direct flame-based hydrogen combustion, CHC is relatively safe as it foregoes COx, CH4, and under certain conditions NOx formation. More so, the risk of blow-off (flame extinguished due to the high fuel flow speed required for H2 combustion) is adverted. CHC is, however, perplexed by the occurrence of hotspots, which are defined as areas where the localized surface temperature is higher than the average surface temperature over the catalyst surface. Hotspots may result in hydrogen’s autoignition and accelerated catalyst degradation. In this review, catalyst materials along with the hydrogen technologies investigated for CHC applications were discussed. We showed that although significant research has been dedicated to CHC, relatively limited commercial applications have been identified up to date. We further showed the effect of catalyst support selection on the performance and durability of CHC catalysts, as well as a holistic summary of existing catalysts used for various CHC applications and catalytic burners. Lastly, the relevance of CHC applications for safety purposes was demonstrated.