Hydrogenation Pathway Research Articles

A comparative well-to-wheel analysis of renewable energy pathways for hydrogen and battery electric vehicles

Renewable hydrogen and batteries are pivotal not only for promoting renewable energy adoption but also for serving as key components in electric vehicles. While multiple hydrogen-based and battery-based pathways exist for linking renewable energy to automotive powertrains, comprehensive evaluations of them are lacking, especially in the context of long-distance energy transmission in China. This study aims to fill this gap by offering an in-depth well-to-wheel (WTW) analysis of costs and CO2 emissions across various pathways. The pathways involve two energy storage mediums - hydrogen and battery, five transport options, and three automotive powertrains - Internal Combustion Engine Vehicle (ICEV), Fuel Cell Electric Vehicle (FCEV), and Battery Electric Vehicle (BEV). How the electricity price, storage duration, and transport distance influence these pathways is also examined. The results show that the battery-based pathway offers the lowest WTW cost and CO2 emissions in BEV applications. Hydrogen-based pathways are not economically feasible for ICEVs. Importantly, the indirect use of hydrogen in BEVs - H2 for power generation - outperforms its direct use in FCEVs and ICEVs in both cost and emissions. The battery-based pathway is significantly affected by storage duration and becomes less feasible for durations exceeding one day. The most cost-efficient hydrogen transport methods are identified for different transport distances and electricity prices. This research may provide valuable insights for the planning of the hydrogen industry, automotive decarbonization and renewable energy development in China.

Selective Deep Hydrogenation of Acenaphthene to High‐Density Fuel On Supported Ru Catalysts: The Role of Strong Metal‐Support Interaction

AbstractDeveloping high‐performance aviation fuel is highly desired for the rapid development of supersonic aircraft. Herein, selective deep hydrogenation of polycyclic aromatics to a high‐density fuel is developed over a Ru‐based catalyst. The influences of strong Ru‐support interaction on tailoring the reaction pathways of acenaphthene hydrogenation were investigated using different oxide supports (SiO2, CeO2, TiO2). Ru/CeO2 and Ru/TiO2 with strong SMSI possess abundant electron‐deficient Ruδ+ species which exhibit a good ability to promote H2 dissociation and increase the isomerization rate of saturated aromatic compounds. Due to the enhanced adsorption of aromatic molecules, Ru/CeO2 (1.30 μmol min−1 g−1) exhibits superior catalytic activity in comparison to Ru/TiO2 (1.25 μmol min−1 g−1) during acenaphthene hydrosaturation, while Ru/TiO2 exhibits the highest isomerization reaction rate (7.60×10−2 μmol min−1 g−1) because of its excellent hydrogen spillover ability and high content of Ruδ+ species. The best catalytic activity with 96 % selectivity of ccc‐perhydroacenaphthene was achieved on Ru/TiO2, and an isomerization mechanism of perhydroacenaphthene isomers was proposed.

Iron-doping regulated light absorption and active sites in LiTaO3 single crystal for photocatalytic nitrogen reduction

In contrast to research on active sites in nanomaterials, lithium tantalate single crystals, known for their exceptional optical properties and long-range ordered lattice structure, present a promising avenue for in-depth exploration of photocatalytic reaction systems with fewer constraints imposed by surface chemistry. Typically, the isotropy of a specific facet provides a perfect support for studying heteroatom doping. Herein, this work delves into the intrinsic catalytic sites for photocatalytic nitrogen fixation in iron-doped lithium tantalate single crystals. The presence of iron not only modifies the electronic structure of lithium tantalate, improving its light absorption capacity, but also functions as an active site for the nitrogen adsorption and activation. The photocatalytic ammonia production rate of the iron-doped lithium tantalate in pure water is maximum 26.95 μg cm−2 h−1, which is three times higher than that of undoped lithium tantalate. The combination of first-principles simulations with in situ characterizations confirms that iron doping promotes the rate-determining step and changes the pathway of hydrogenation to associative alternating. This study provides a new perspective on in-depth investigation of intrinsic catalytic active sites in photocatalysis and other catalytic processes.

The Effect of Environmental Smart Technology and Renewable Energy on Carbon Footprint: A Sustainability Perspective from the MENA Region

This paper looks at the changing impact of renewable energy and green innovation on the carbon footprint of eight MENA nations between 2000 and 2020. We investigate this by using the panel Q-ARDL model for the first time, and we find that, with various impacts across different quantiles, a rise in green innovation and renewable energy greatly boosts environmental sustainability in the short run. In the long run, this effect becomes increasingly more noticeable. According to our analysis, the chosen MENA countries quickly embraced energy storage, solar hydrogen, and other technology pathways to diversify their energy mix, which was a turning point in the fight against climate change. Although these factors have been separately examined in different studies, our research merges them into a single non-parametric model. This research is significant as it provides empirical evidence on the efficiency of green innovation and renewable energy policies, and it will guide policymakers and energy stakeholders in developing strategies to achieve sustainable development goals.

The Economic Competitiveness of Hydrogen Fuel Cell-Powered Trucks: A Review of Total Cost of Ownership Estimates

This paper investigates the economic competitiveness of hydrogen-powered trucks. It reviews the growing number of papers that provide an estimate of the total cost of ownership (TCO) of hydrogen-powered trucks relative to their diesel equivalents. It examines the methodology applied, the variables considered, the data used for estimation, and the results obtained. All reviewed studies conclude that hydrogen-powered trucks are not currently cost-competitive, while they might become competitive after 2030. The conclusion holds across truck types and sizes, hydrogen pathways, mission profiles, and countries. However, we find that there is still a huge area of uncertainty regarding the purchase price of hydrogen-powered trucks and the cost of hydrogen, which hampers the reliability of the results obtained. Various areas of methodological improvements are suggested.

The Impact of Electron Donating and Withdrawing Groups on Electrochemical Hydrogenolysis and Hydrogenation of Carbonyl Compounds.

The hydrogenolysis or hydrodeoxygenation of a carbonyl group, where the C═O group is converted to a CH2 group, is of significant interest in a variety of fields. A challenge in electrochemically achieving hydrogenolysis of a carbonyl group with high selectivity is that electrochemical hydrogenation of a carbonyl group, which converts the C═O group to an alcohol group (CH-OH), is demonstrated not to be the initial step of hydrogenolysis. Instead, hydrogenation and hydrogenolysis occur in parallel, and they are competing reactions. This means that although both hydrogenolysis and hydrogenation require adding H atoms to the carbonyl group, they involve different intermediates formed on the electrode surface. Thus, revealing the difference in intermediates, transition states, and kinetic barriers for hydrogenolysis and hydrogenation pathways is the key to understanding and controlling hydrogenolysis/hydrogenation selectivity of carbonyl compounds. In this study, we aimed to identify features of reactant molecules that can affect their hydrogenolysis/hydrogenation selectivity on a Zn electrode that was previously shown to promote hydrogenolysis over hydrogenation. In particular, we examined the electrochemical reduction of para-substituted benzaldehyde compounds with substituent groups having different electron donating/withdrawing abilities. Our results show a strikingly systematic impact of the substituent group where a stronger electron-donating group promotes hydrogenolysis and a stronger electron-withdrawing group promotes hydrogenation. These experimental results are presented with computational results explaining the substituent effects on the thermodynamics and kinetics of electrochemical hydrogenolysis and hydrogenation pathways, which also provide critically needed information and insights into the transition states involved with these pathways.

Comparative analysis of hydrogen production pathways for emethanol synthesis to decarbonise industry

Methane pyrolysis and water electrolysis offer alternative hydrogen pathways to methane reforming that utilise renewable power and avoid generating carbon dioxide (CO2). On a scope 1 and 2 basis, both technologies have the potential to generate carbon neutral emethanol fuel when combined with biogenic CO2. However, pyrolysis requires significantly less energy and has a lower capital expenditure (CAPEX). Being a more nascent technology, it also has upside potential for cost reductions and valorisation of the solid carbon by-product can yield lower hydrogen costs than the incumbent technology, however, limited demand from existing markets is a potential constraint. Industry decarbonisation is constrained due to a lack of available renewables and hydrogen infrastructure. Pyrolysis offers a potential cost-effective use of the available renewable assets in the early stages while the carbon by-product is not a constraint and until sufficient renewable infrastructure is in place to support water electrolysis at a cost-effective scale.

Enhanced nitrite electroreduction to ammonia via interfacial dual-site adsorption

The nitrite (NO2−) to ammonia (NH3) electroreduction reaction (NO2−RR) would be impeded by sluggish proton-coupled electron transfer kinetics and competitive hydrogen evolution reaction (HER). A key to improving the NH3 selectivity is to facilitate adsorption and activation of NO2−, which is generally undesirable in unitary species. In this work, an efficient NO2−RR catalyst is constructed by cooperating Pd with In2O3, in which NO2− could adsorb on interfacial dual-site through “Pd–N–O–In” linkage, leading to strengthened NO2− adsorption and easier N=O bond cleavage than that on unitary Pd or In2O3. Moreover, the Pd/In2O3 composite exhibits moderate H* adsorption, which may facilitate protonation kinetics while inhibiting competitive HER. As a result, it exhibits a fairly high NH3 yield rate of 622.76 mmol h−1 g−1cat with a Faradaic efficiency (FE) of 95.72%, good selectivity of 91.96%, and cycling stability towards the NO2−RR, surpassing unitary In2O3 and Pd/C electrocatalysts. Besides, computed results indicate that NH3 production on Pd/In2O3 follows the deoxidation to hydrogenation pathway. This work highlights the significance of H* and NO2− adsorption modulation and N=O activation in NO2−RR electrochemistry by creating synergy between a mediocre catalyst with an appropriate cooperator.

Regulating the electronic property of iron catalysts for higher alcohols synthesis from CO2 hydrogenation

The electronic property of a catalyst is crucial to the generation of key reaction intermediates for targeted synthesis. Herein, we reported a strategy by modifying iron catalysts with sulfate and alkali metal (Li, Na, or K) to regulate the electronic property and optimize the reaction pathways for CO2 hydrogenation to higher alcohols. The characterizations demonstrated the influencing relationship between the electronic property of iron catalysts and the catalytic capabilities for CO dissociation, non-dissociated CO activation and catalytic hydrogenation, which were critical to selective synthesis of higher alcohols. Na-S modification was proven more effective to balance the multiple capabilities required for higher alcohols synthesis and the NaS-Fe catalyst gave a higher C2+OH yield in CO2 hydrogenation. DFT calculations further validated the advantage of Na-S modification from the aspects of CO adsorption and C−C coupling. This strategy provides more flexibility in site regulation and applies to catalyst design for many reactions.

Open energy system modelling for low-emission hydrogen roadmap planning: The case of Colombia

Climate change is driving the need for new approaches to energy production and utilization globally, contributing to the mitigation of greenhouse gas (GHG) emissions. Low-emission hydrogen is recognized as a key energy vector for decarbonization, and numerous countries are currently evaluating strategies and roadmaps for its integration. Colombia, with its abundant renewable resources, is poised as a potential player in hydrogen production. This study presents a techno-economic assessment of hydrogen pathways and their cross-sectoral interactions within the Colombian energy system. By employing an open energy system optimization framework (OSeMOSYS), we modelled a detailed supply-demand hydrogen chain and analysed a series of scenarios from 2021 to 2050, including a sensitivity analysis. Our results show that hydrogen pathways will require 2–6.4 Mt/year in hydrogen production, 8–27 GW in new installed capacity, and US$50–80 billion in investments, with favourable impacts in GHG mitigation, energy imports, and socioeconomic benefits. We use these findings to suggest an update to the targets of the current National Hydrogen Roadmap focused on a higher ambition to deploy a full hydrogen economy. Our open methodology provides a valuable tool for conducting further assessments in developing countries interested in defining low-emission hydrogen roadmaps.

In situ exsolution to fabricate interfacial Ni0/Niδ+ sites for regulating reaction pathways in hydrogenation

Regulating the selectivity of reaction pathways to desirable products via controlling adsorption/activation behaviors towards reactants is significant for the design of excellent catalysts for selective hydrogenation but remains challenging. Exemplified with dimethyl oxalate (DMO) hydrogenation, we herein propose an in situ exsolution strategy for constructing interfacial Ni0/Niδ+ sites by using pre-synthesized Ni phyllosilicate as the precursor to control the reaction pathways of selective hydrogenation. Structural characterizations, including in situ spectroscopic and isotopic studies, and theoretical calculations elucidate that the interfacial Ni0/Niδ+ sites can selectively activate monoester group of DMO via a tilted adsorption configuration and hence boost hydrogen dissociation. With such activation behaviors the reaction pathway is steered to methyl glycolate, other than the pathway to ethylene glycol on the reference active sites where both ester groups are activated and methyl formate is formed via breaking the C–C bond of DMO.

Incorporating platinum circular economy into China's hydrogen pathways toward carbon neutrality.

Hydrogen is gaining tremendous traction in China as the fuel of the future to support the country's carbon neutrality ambition. Despite that hydrogen as fuel largely hinges on the supply of platinum (Pt), the dynamic interlinkage between Pt supply challenges, hydrogen development pathways, and climate targets in China has yet to be deeply analyzed. Here, we adopt an integrated assessment model to address this important concern and corresponding strategies for China. The results indicate that the booming hydrogen development would drive China's cumulative demand for Pt metal to reach 4,200-5,000 tons. Much of this demand, met through a limited supply pattern, is vulnerable to price volatility and heightened geopolitical risks, which can be mitigated through circular economy strategies. Consequently, a coordinated approach to leverage both global sustainable Pt sourcing and a robust domestic Pt circular economy is imperative for ensuring cost-effective hydrogen production, aligned with a climate-safe future.

Realism at the end of the rainbow? An argument towards diversifying hydrogen in EU regulation

Abstract The European Union’s (EU) decarbonization strategy involves hydrogen as an integral pillar. Since hydrogen is a secondary energy carrier, meaning it must be manufactured, not all hydrogen is made equal. Renewable hydrogen or RFNBOs (Renewable Fuel of Non-Biological Origins) have been given high priority by the EU in their strategy to establish a market for hydrogen. The EU’s creation of RFNBO usage objectives is a step towards establishing a demand-side market. One such goal is to bring into the EU up to 10 million tonnes of renewable hydrogen. However, it is doubtful that this large amount can be reached given the strict criteria for what qualifies as renewable hydrogen and, thus, as RFNBO. This article analyses key provisions of the EU framework that affect the EU’s aim to produce and import up to 20 million tonnes of hydrogen overall. It concludes the EU’s emphasis on RFNBOs rather than a broader range of hydrogen pathways undermines the goal of rapidly developing a hydrogen market. Using turquoise hydrogen as a case study, the article shows how the EU’s decarbonization efforts would be aided, trade would be enabled, and fragmentation would be decreased if targets were expanded to encompass additional forms of hydrogen.

N-Alkylation through the Borrowing Hydrogen Pathway Catalyzed by the Metal–Organic Framework-Supported Iridium–Monophosphine Complex

N-Alkylation through the Borrowing Hydrogen Pathway Catalyzed by the Metal–Organic Framework-Supported Iridium–Monophosphine Complex

Upcycling of polyethylene to gasoline through a self-supplied hydrogen strategy in a layered self-pillared zeolite

Conversion of plastic wastes to valuable carbon resources without using noble metal catalysts or external hydrogen remains a challenging task. Here we report a layered self-pillared zeolite that enables the conversion of polyethylene to gasoline with a remarkable selectivity of 99% and yields of >80% in 4 h at 240 °C. The liquid product is primarily composed of branched alkanes (selectivity of 72%), affording a high research octane number of 88.0 that is comparable to commercial gasoline (86.6). In situ inelastic neutron scattering, small-angle neutron scattering, solid-state nuclear magnetic resonance, X-ray absorption spectroscopy and isotope-labelling experiments reveal that the activation of polyethylene is promoted by the open framework tri-coordinated Al sites of the zeolite, followed by β-scission and isomerization on Brönsted acids sites, accompanied by hydride transfer over open framework tri-coordinated Al sites through a self-supplied hydrogen pathway to yield selectivity to branched alkanes. This study shows the potential of layered zeolite materials in enabling the upcycling of plastic wastes.

Abating CO2 and non-CO2 emissions with hydrogen propulsion

Abstract This contribution focuses on the abatement with hydrogen of CO2 and non-CO2 emissions. It is agenda-setting in two respects. Firstly, it challenges the globally accepted hydrocarbon sustainable aviation fuel (SAF) pathway to sustainability and recommends that our industry accelerates along the hydrogen pathway to ‘green’ aviation. Secondly, it reports a philosophical and analytical investigation of appropriate accuracy on abatement strategies for nitrogen oxides and contrails of large hydrogen airliners. For the second contribution, a comparison is made of nitrogen oxide emissions and contrail avoidance options of two hydrogen airliners and a conventional airliner of similar passenger capacity. The hydrogen aircraft are representative of the first and second innovation waves where the main difference is the weight of the hydrogen tanks. Flights of 1000, 2000, 4000 and 8000 nautical miles are explored. Cranfield’s state of the art simulators for propulsion system integration and gas turbine performance (Orion and Turbomatch) were used for this. There are two primary contributions to knowledge. The first is a new set of questions to be asked of SAF and hydrogen decarbonising features. The second is the quantification of the benefits from hydrogen on non-CO2 emissions. For the second generation of long-range hydrogen-fuelled aircraft having gas turbine propulsion, lighter tanks (needing less thrust and lower gas temperatures) are anticipated to reduce NOx emissions by over 20%; in the case of contrails, the preliminary findings indicate that regardless of the fuel, contrails could largely be avoided with fuel-burn penalties of a few per cent. Mitigating action is only needed for a small fraction of flights. For conventional aircraft this penalty results in more CO2, while for hydrogen aircraft the additional emission is water vapour. The conclusion is that our research community should continue to consider hydrogen as the key ‘greening’ option for aviation, notwithstanding the very significant costs of transition.

Review of Mechanism Investigations and Catalyst Developments for CO2 Hydrogenation to Alcohols

Heterogeneous thermal-catalytic CO2 hydrogenation to alcohols using renewable energy is a highly attractive approach for recycling greenhouse gases into high-value chemicals and fuels, thereby reducing the dependence on fossil fuels, while simultaneously mitigating the CO2 emission and environmental problems. Currently, great advances have been made on the heterogeneous catalysts, but an in-depth and more comprehensive understanding to further promote this reaction process is still lacking. Herein, we highlight the thermodynamic and kinetic analysis of CO2 hydrogenation reaction firstly. Then, various reaction pathways for CO2 hydrogenation to methanol and higher alcohols (C2+ alcohols) have been discussed in detail, respectively, by combining the experimental studies and density functional theory calculations. On this basis, the key factors influencing the reaction performance, such as metal dispersion, support modification, promoter addition and their structural optimization, are summarized on the metal-based and metal-oxide-based catalysts. In addition, the catalytic performance of CO2 hydrogenation to alcohols and the relationship between structure and properties are mainly summarized and analyzed in the past five years. To conclude, the current challenges and potential strategies in catalyst design, structural characterization and reaction mechanisms are presented for CO2 hydrogenation to alcohols.

The reaction of nonacarbonyldiiron with 8‐alkynyloxyquinolines: Alkynyl activation, cyclization via C‐N bond formation, and C‐H bond cleavage

In this work, the reactions of nonacarbonyldiiron with 8‐alkynyloxyquinoline ligands (L1‐L3) and their resultant iron carbonyl complexes (1a, 1b, 2, and 3) are described. The complexes including the ligands were fully characterized by using a variety of spectroscopic techniques. The four complexes were also crystallographically determined. In the reactions, the quinoline N atom underwent cyclization to form a quinolinium skeleton while the C‐H bond of the quinoline at position 2 or the substituted methyl group was cleaved to form Fe‐C bond(s). Meanwhile, the alkynyl triple bond was reduced to a single bond (1a) or double bonds (1b, 2, and 3) to further coordinate the iron in σ‐bonds or η‐bonds. Particularly, pathways of hydrogenation (1a and 2) and/or dehydrogenation (1b and 3) were accompanied by the reactions. Moreover, the oxidation states of the iron centers in these complexes were identified through analyses of their bond formation, FTIR and NMR spectroscopic signals (1H NMR and DEPT‐135) in combination with their diamagnetic nature, that is, iron (0) for 2 and iron (I) for the rest of the diiron complexes.

Carbon abatement cost evolution in the forthcoming hydrogen valleys by following different hydrogen pathways

The need to develop a forthcoming hydrogen economy emphasises the emerging concept of ‘hydrogen valleys', where hydrogen production and consumption are being developed. This study assesses the Levelized Cost of Hydrogen (LCOH) and Carbon Abatement Cost (CAC) for various hydrogen end-use applications within the context of a hydrogen valley located in the southern Italy over different time horizons (Today 2023, Mid-Term 2030, Long-Term 2050). Examined applications include blending into the gas grid, reconversion into electricity for grid balancing by means of fuel cells, hydrogen refuelling stations for fuel cell electric vehicles (FCEVs), synthetic methane production, and electro-fuel synthesis. Employing a parametric approach, the study compares LCOH and decarbonisation costs across different pathways. Results indicate current LCOH production values of 3.66–4.90 €/kgH2, projected to decrease to 1.41–1.94 €/kgH2 by 2050. Decarbonisation cost analysis identifies blending and FCEV scenarios as the most cost-effective, contrasting with Power-to-Power scenarios, particularly in the mid and long terms.

Approach to Low Contact Resistance Formation on Buried Interface in Oxide Thin-Film Transistors: Utilization of Palladium-Mediated Hydrogen Pathway.

Amorphous oxide semiconductors (AOSs) with low off-currents and processing temperatures offer promising alternative materials for next-generation high-density memory devices. The complex vertical stacking process of memory devices significantly increases the probability of encountering internal contact issues. Conventional surface treatment methods developed for planar devices necessitate efficient approaches to eliminate contact issues at deep internal interfaces in the nanoscale complex structures of AOS devices. In this work, we report the pioneering use of palladium thin film as a high-efficiency active hydrogen transfer pathway from the outside to the internal contact interface via low-temperature postannealing in the H2 atmosphere, and the formation of highly conductive metallic interlayer effectively solves the contact issues at the deeply buried interfaces in devices. The application of this method reduced the contact resistance of Pd electrodes/amorphous indium-gallium-zinc oxide (a-IGZO) thin-film by 2 orders of magnitude, and thereby the mobility of thin-film transistor was increased from 3.2 cm2 V-1 s-1 to nearly 20 cm2 V-1 s-1, preserving an excellent bias stress stability. This technology has wide applicability for the solution of contact resistance issues in oxide semiconductor devices with complex architectures.