The development of efficient catalysts for the production of 2,5-furandicarboxylic acid (FDCA) from 5-(hydroxymethyl)furfural (HMF) is crucial to reduce the environmental footprint and achieve economically favorable conditions for its use in polyethylene 2,5-furandicarboxylate (PEF) synthesis. In this work, we demonstrated the possibility of tuning the electronic properties of Au nanoparticle-based catalysts via polymeric stabilizers to control HMF oxidation mechanism and product distribution. Polyvinyl alcohol (PVA), polyvinyl amine (PVAm), and poly(N-vinyl amine-co-vinyl alcohol) (PVA-co-PVAm) copolymers were synthesized with various compositions to evaluate the effect of functional groups on ligand–metal interactions. The presence of amino groups increases electron donation to Au, as confirmed by DFT calculations of monomer adsorption on cluster models of amorphous Au NPs. DFT investigations, NMR relaxation studies, and catalytic studies further revealed that increasing electron-donor groups modifies the reaction mechanism and enhances selectivity, particularly through manipulating the adsorption of reaction intermediates. These results provide mechanistic insights into the role of stabilizers and the active phase in directing specific reaction pathways. This understanding enables the rational design of polymeric ligands to enhance catalyst performance for aerobic oxidation of biomass-derived molecules in water under mild conditions, underscoring the role of stabilizer engineering in achieving selective and sustainable catalytic processes.

2D borophene has long been proposed as a promising hydrogen storage material, but experimental demonstrations remain limited to boron hydride sheets derived from MgB₂. Here, we report the synthesis of potassium-doped borophane (BH) nanosheets, which serve as a high-capacity, reversible hydrogen storage platform and metal-free reducing agent. Through selective hydride transfer, the BH sheet efficiently converted levulinic acid (LA) to γ-valerolactone (GVL) under mild reaction conditions. Density functional theory (DFT) predicts a theoretical hydrogen content of 4.2 wt.% for the potassium-doped BH sheet. Remarkably, the dehydrogenated BH sheets can be partially regenerated under 50 bar H₂, demonstrating reversible hydrogen storage. This work serves as an experimental validation for alkali-metal-modified borophanes acting as a multifunctional material for hydrogen storage and transfer, opening avenues for sustainable energy and other applications.

Thermochemical Water-Splitting (TCWS) is a promising approach for generating clean hydrogen (H₂) by employing the waste heat originating from different sources. High-temperature requirements and temperature swing approach hinder the widespread adoption of TCWS for clean hydrogen production. This study explores ceria nanorods (CeNRs) as a potential solution for overcoming these limitations. Herein, we report, the TCWS in a fixed bed reactor using CeNRs at low and constant temperature of 400 °C. We systematically explore the influence of synthesis parameters on the resulting CeNRs, including the selection of ceria precursor, effect of calcination, and their impact in TCWS. It was found that CeNRs prepared using cerium chloride as the precursor exhibited enhanced TCWS activity, resulting significantly higher total H₂ yield 4.74 mL/g, at a constant temperature of 400 °C in three redox cycles. Moreover, X-ray Photoelectron Spectroscopy (XPS) analysis confirms the presence of both Ce³⁺ and Ce⁴⁺ states within the structure, with Ce³⁺ constituting approximately 30 % and Ce⁴⁺ accounting for approximately 70 % of the total cerium content. Additionally, Raman spectroscopy corroborates the presence of a higher concentration of oxygen vacancy which are beneficial for increasing the hydrogen production. We demonstrate that ceria in its nanorod structure having exposed higher proportions of (110) and (100) planes and higher concentration of oxygen vacancies is beneficial for lowering TCWS temperature as well as increasing the hydrogen yield.

Multiphasic reaction of bicarbonate hydrogenation to form formate using homogeneous Ru PNP pincer catalyst in a continuous flow tubular reactor is reported. The reaction system consists of three phases. Catalyst is dissolved in toluene while potassium bicarbonate is dissolved in water. The significance of efficient mixing among the organic phase, aqueous phase and gaseous hydrogen to improve hydrogenation reaction by using different inert packing materials is studied by operando visualization and also quantitatively discussed. The bicarbonate conversion of up to 67% is achieved after optimization of important reaction and reactor parameters. The designed reactor setup comprised of effective recycling system that recycles the catalyst with >99% activity.

Higher alcohol (HA) synthesis via the hydrogenation of CO₂ constitutes a relatively new and exciting field of research that has the potential to help towards the de-carbonization of the energy sector. The process poses formidable challenges, as it demands the formation of at least one C-C bond, when CO₂ is thermodynamically stable, fully oxidized and kinetically inert. This work provides a comprehensive and critical literature review of the catalytic formulations that have been employed, in both fixed-bed and batch reactors, which include noble metal catalysts, transition metal-based systems, post-transition metal catalysts, bimetallic, multimetallic/multifunctional catalysts, Metal Organic Frameworks (MOFs), perovskite-, and zeolite-based catalysts. The critical role of promoters and supports and the effect that the reaction conditions have on performance are also discussed. Emphasis has been given to single atom catalysts (SACs), as the high specific activity of these systems seems to hold great promise for the reaction at hand. Breakthroughs made by employing the concept of tandem catalysis are also critically analyzed. This review paper also discusses the thermodynamic aspects of the reaction and the insights that have been gained regarding the reaction mechanism. Finally, it provides an overview of the direction that research may move to into the future.

In this study, Ni catalysts supported on Pr-doped CeO₂ are studied for the CO₂ methanation reaction and the effect of Pr doping on the physicochemical properties and the catalytic performance is thoroughly evaluated. It is shown, that Pr³⁺ ions can substitute Ce⁴⁺ ones in the support lattice, thereby introducing a high population of oxygen vacancies, which act as active sites for CO₂ chemisorption. Pr doping can also act to reduce the crystallite size of metallic Ni, thus promoting the active metal dispersion. Catalytic performance evaluation evidences the promoting effect of low Pr loadings (5 at% and 10 at%) towards a higher catalytic activity and lower CO₂ activation energy. On the other hand, higher Pr contents negate the positive effects on the catalytic activity by decreasing the oxygen vacancy population, thereby creating a volcano-type trend towards an optimum amount of aliovalent substitution.

Climate change, the greenhouse effect and fossil fuel extraction have gained a growing interest in research and industrial circles to provide alternative chemicals and fuel synthesis technologies. Carbon dioxide (CO₂) hydrogenation to value-added chemicals using hydrogen (H₂) from renewable power (solar, wind) offers a unique solution. From this aspect this review describes the various products, namely methane (C₁), methanol, ethanol, dimethyl ether (DME) and hydrocarbons (HC_s) originating via CO₂ hydrogenation reaction. In addition, conventional reactor units for the CO₂ hydrogenation process are explained, as well as different types of microreactors with key pathways to determine catalyst activity and selectivity of the value-added chemicals. Finally, limitations between conventional units and microreactors and future directions for CO₂ hydrogenation are detailed and discussed. The benefits of such set-ups in providing platforms that could be utilized in the future for major scale-up and industrial operation are also emphasized.

The need to replace fossil fuels with sustainable alternatives has been a critical issue in recent years. Hydrogen fuel is a promising alternative to fossil fuels because of its wide availability and high energy density. For the very first time, novel microreactor configurations for the formic acid decomposition have been studied using computational modeling methodologies. The decomposition of formic acid using a commercial 5 wt % Pd/C catalyst, under mild conditions, has been assessed in packed bed, coated wall, and membrane microreactors. Computational fluid dynamics (CFD) was utilized to develop the comprehensive heterogeneous microreactor models. The CFD modeling study begins with the development of a packed bed microreactor to validate the experimental work, subsequently followed by the theoretical development of novel microreactor configurations to perform further studies. Previous work using CFD modeling had predicted that the deactivation of the Pd/C catalyst was due to the production of the poisoning species CO during the reaction. The novel membrane microreactor facilitates the continuous removal of CO during the reaction, therefore prolonging the lifetime of the catalyst and enhancing the formic acid conversion by approximately 40% when compared to the other microreactor configurations. For all microreactors studied, the formic acid conversion increases as the temperature increases, and the liquid flow rate decreases. Further studies revealed that all microreactor configurations had negligible internal and external pore diffusion resistances. The detailed models developed in this work have provided an interesting insight into the intensification of the formic acid decomposition reaction over a Pd/C catalyst.

The interest in and need for carbon-free fuels that do not rely on fossil fuels are constantly growing from both environmental and energetic perspectives. Green hydrogen production is at the core of the transition away from conventional fuels. Along with popularly investigated pathways for hydrogen production, thermochemical water splitting using redox materials is an interesting option for utilizing thermal energy, as this approach makes use of temperature looping over the material to produce hydrogen from water. Herein, two-step thermochemical water splitting processes are discussed and the key aspects are analyzed using the most relevant information present in the literature. Redox materials and their compositions, which have been proven to be efficient for this reaction, are reported. Attention is focused on non-volatile redox oxides, as the quenching step required for volatile redox materials is unnecessary. Reactors that could be used to conduct the reduction and oxidation reaction are discussed. The most promising materials are compared to each other using a multi-criteria analysis, providing a direction for future research. As evident, ferrite supported on yttrium-stabilized zirconia, ceria doped with zirconia or samarium and ferrite doped with nickel as the core and an yttrium (III) oxide shell are promising choices. Isothermal cycling and lowering of the reduction temperature are outlined as future directions towards increasing hydrogen yields and improving the cyclability.

Cu/ZnO-based catalysts for methanol synthesis by COx hydrogenation are widely prepared via co-precipitation of sodium carbonates and nitrate salts, which eventually produces a large amount of wastewater from the washing step to remove sodium (Na+) and/or nitrate (NO3-) residues. The step is inevitable since the remaining Na+ acts as a catalyst poison whereas leftover NO3- induces metal agglomeration during the calcination. In this study, sodium- and nitrate-free hydroxy-carbonate precursors were prepared via urea hydrolysis co-precipitation of acetate salt and compared with the case using nitrate salts. The Cu/ZnO catalysts derived from calcination of the washed and unwashed precursors show catalytic performance comparable to the commercial Cu/ZnO/Al2O3 catalyst in CO2 hydrogenation at 240-280 °C and 331 bar. By the combination of urea hydrolysis and the nitrate-free precipitants, the catalyst preparation is simpler with fewer steps, even without the need for a washing step and pH control, rendering the synthesis more sustainable. This journal is