Bar H2 Research Articles

Hydrogenation Catalysis by Hydrogen Spillover on Platinum‐Functionalized Heterogeneous Boronic Acid‐Polyoxometalates

AbstractThe activation of molecular hydrogen is a key process in catalysis. Here, we demonstrate how polyoxometalate (POM)‐based heterogeneous compounds functionalized with Platinum particles activate H2 by synergism between a hydrogen spillover mechanism and electron‐proton transfer by the POM. This interplay facilitates the selective catalytic reduction of olefins and nitroarenes with high functional group tolerance. A family of polyoxotungstates covalently functionalized with boronic acids is reported. In the solid‐state, the compounds are held together by non‐covalent interactions (π–π stacking and hydrogen bonding). The resulting heterogeneous nanoscale particles form stable colloidal dispersions in acetonitrile and can be surface‐functionalized with platinum nanoparticles by in situ photoreduction. The resulting materials show excellent catalytic activity in hydrogenation of olefins and nitrobenzene derivatives under mild conditions (1 bar H2 and room temperature).

Encapsulation of Palladium Carbide Subnanometric Species in Zeolite Boosts Highly Selective Semihydrogenation of Alkynes.

The selective hydrogenation of alkynes to alkenes is a crucial step in the synthesis of fine chemicals. However, the widely utilized palladium (Pd)-based catalysts often suffer from poor selectivity. In this work, we demonstrate a carbonization-reduction method to create palladium carbide subnanometric species within pure silicate MFI zeolite. The carbon species can modify the electronic and steric characteristics of Pd species by forming the predominant Pd-C4 structure and, meanwhile, facilitate the desorption of alkenes by forming the Si-O-C structure with zeolite framework, as validated by the state-of-the-art characterizations and theoretical calculations. The developed catalyst shows superior performance in the selective hydrogenation of alkynes over mild conditions (298 K, 2 bar H2 ), with 99 % selectivity to styrene at a complete conversion of phenylacetylene. In contrast, the zeolite-encapsulated carbon-free Pd catalyst and the commercial Lindlar catalyst show only 15 % and 14 % selectivity to styrene, respectively, under identical reaction conditions. The zeolite-confined Pd-carbide subnanoclusters promise their superior properties in semihydrogenation of alkynes.

Encapsulation of Palladium Carbide Subnanometric Species in Zeolite Boosts Highly Selective Semihydrogenation of Alkynes

AbstractThe selective hydrogenation of alkynes to alkenes is a crucial step in the synthesis of fine chemicals. However, the widely utilized palladium (Pd)‐based catalysts often suffer from poor selectivity. In this work, we demonstrate a carbonization‐reduction method to create palladium carbide subnanometric species within pure silicate MFI zeolite. The carbon species can modify the electronic and steric characteristics of Pd species by forming the predominant Pd−C4 structure and, meanwhile, facilitate the desorption of alkenes by forming the Si−O−C structure with zeolite framework, as validated by the state‐of‐the‐art characterizations and theoretical calculations. The developed catalyst shows superior performance in the selective hydrogenation of alkynes over mild conditions (298 K, 2 bar H2), with 99 % selectivity to styrene at a complete conversion of phenylacetylene. In contrast, the zeolite‐encapsulated carbon‐free Pd catalyst and the commercial Lindlar catalyst show only 15 % and 14 % selectivity to styrene, respectively, under identical reaction conditions. The zeolite‐confined Pd‐carbide subnanoclusters promise their superior properties in semihydrogenation of alkynes.

CO2 Capture and Direct Air CO2 Capture Followed by Integrated Conversion to Methane Assisted by Metal Hydroxides and a Ru/Al2O3 Catalyst

AbstractRising CO2 levels are leading to an increase in atmospheric greenhouse gas effect. Hydroxide salts have previously been shown to be promising reagents for capturing CO2. Utilizing a 5 %Ru/Al2O3 catalyst, the carbonates obtained through CO2 capture can then be hydrogenated to methane. This conversion occurs at relatively mild temperatures from 200 °C to 250 °C under 40 to 70 bar H2 with yields of up to 100 %. Natural sources of calcium carbonate, like eggshells and seashells, can also be partially converted to methane. The direct air CO2 capture and conversion of CO2 to methane was achieved as well in quantitative yields.

Phosphine-Enhanced Semi-Hydrogenation of Phenylacetylene by Cobalt Phosphide Nano-Urchins.

Transition metal phosphides are promising, selective, and air-stable nanocatalysts for hydrogenation reactions. However, they often require fairly high temperatures and H2 pressures to provide quantitative conversions. This work reports the positive effect of phosphine additives on the activity of cobalt phosphide nano-urchins for the semi-hydrogenation of phenylacetylene. While the nanocatalyst's activity was low under mild conditions (7 bar of H2 , 100 °C), the addition of a catalytic amount of phosphine remarkably increased the conversion, e. g., from 13 % to 98 % in the case of Pn Bu3 . The heterogeneous nature of the catalyst was confirmed by negative supernatant activity tests. The catalyst integrity was carefully verified by post-mortem analyses (TEM, XPS, and liquid 31 P NMR). A stereo-electronic map was proposed to rationalize the activity enhancement provided over a selection of nine phosphines: the strongest effect was observed for low to moderately hindered phosphines, associated with strong electron donor abilities. A threshold in phosphine stoichiometry was revealed for the enhancement of activity to occur, which was related to the ratio of phosphine to surface cobalt atoms.

Highly Efficient Depolymerization of Waste Polyesters Enabled by Transesterification/Hydrogenation Relay Under Mild Conditions.

The efficient depolymerization of polyesters under mild conditions remains a significant challenge. Herein, we demonstrate a highly efficient strategy for the degradation of a diverse array of waste polyesters as low to 80 °C, 1 bar H2. The key to the success ofthis transformation relied on the initial transesterification of macromolecular polyesterinto more degradable oligomeric fragments in the presence of CH3OH and the subsequent hydrogenation by the use of the rationally designed quinaldine-based Ru complex. Controlled experiments and preliminary mechanistic studies disclosed the quinaldine-based catalysts could be hydrogenated to the eventually active species, which has been confirmed by X-ray diffraction analysis and directly used as a catalyst in the hydrogenolysis of polyester. The strong viability and high activity of this new species in protic solvent were explained in detail. Besides, the crucial role of CH3OH in promoting reaction efficiency during the whole process was also elucidated. The synthetic utility of this method was further illustrated by preparing 1,4-cyclohexanedimethanol (CHDM) from waste polyethylene terephthalate (PET).

Evaluation of the reliability of buried gas pipelines exposed to ground movement in the perspective of their use for hydrogen transportation: A state-of-art review

Hydrogen (H2) has been recognized as having the potential to become the cornerstone of a low-carbon energy system. As a result, it has garnered much interest from policymakers and industry as a focus for future infrastructure.
 In its race towards climate neutrality by 2050, the European Union seems to be betting on green hydrogen as a high-potential energy source. Europe envisages to develop more than 11,000 km of pipelines transporting hydrogen in 2030 [2]. The French government seems to prioritize the reuse of gas networks for the transport and storage of H2 [4]. On the other hand, the substitution of gas by hydrogen leads to an evolution of the mechanical characteristics of steel pipelines, and consequently, increases their vulnerability vis-à-vis external stresses (loads, ground movements, natural hazards, etc.). It has been shown that pipeline steel could lose up to 40% of its ductility after exposure to 100 bar H2 [3]. Thus, the reuse of the existing gas networks for the hydrogen transport raises today a set of scientific and technical questions. The problematic of pipelines vulnerability is getting even more serious by both the climate change and the evolution of human activities associated with the ecological transition.
 In the framework of a thesis that we recently started (October 2022), we aim to understand the interaction between buried networks (gas networks reused for hydrogen transport) and ground movements, with a purpose to enhance risk prevention and to reduce the associated consequences. The aim is to establish a reliable analytical model enabling sensitivity studies to be performed and the influence of the uncertainties on the results to be assessed. The outcomes will be also valued by developing fragility curves that constitute operational approaches when assessing damages in an uncertain context.
 The aim of this study is to synthesize the existing research work available in the literature addressing the behaviour of buried pipelines subjected to various ground motion phenomena. This review covers the various modelling approaches and simulation techniques for the soil-pipe system found in the literature. The main limitations of the existing methods are also stated.These studies encompass a diversity of ground motion sources including, but not limited to: Fault movements (strike-slip, normal-slip), soil settlements due to tunnelling, differential ground settlements related to groundwater lowering, and soil liquefaction. The main research methodologies employed are analytical analysis, numerical simulation and experimental testing.
 One way to study the behaviour of the buried pipelines is the analytical modelling based on theoretical analysis [6, 7, 8]. For this approach, reasonable assumptions and simplification are necessary when simulating the pipe-soil system but also the ground movement. Soil-pipe interaction models found in previous study are mainly based on Winkler model, Pasternak model and others. The pipeline material behaviour was considered to have either elastic, bilinear or tri-linear stress-strain response. The adopted simplifying assumptions in the abovementioned studies can be prominent in certain cases of practical interest.
 Analytical models based upon empirical curve fits have also been employed in some studies. The fitted functions can be derived from a numerical parametric analysis, by performing regression analyses on data obtained from a large number of configurations covering different values of the input parameters, such as pipe diameter, burial depth, soil subgrade modulus, pipe elasticity, and maximum displacement of the soil [11]. The derived empirical expressions can be used to directly estimate pipe response induced by a soil settlement.
 Another major way to investigate this topic is the numerical simulation. Numerous studies were carried out using numerical finite element models [10, 12]. The results of these computational methods are becoming increasingly accurate as currently available numerical analysis techniques allow this problem to be solved in a rigorous manner, minimizing the number of required approximations. However, the non-linear behaviour of the pipeline steel, the soil-pipeline interaction and the second-order effects induced by large displacements make these analyses quite challenging.
 Apart from the above analytical and numerical methodologies, there have been a growing number of papers involving the experimental simulation of buried pipes under ground motion. These investigations were based on centrifuge tests [1, 5] and other designed testing apparatus [9].
 However, despite the advancement of modelling techniques, there are still some limitations when examining the behaviour of buried pipelines subjected to ground settlement such as the need for accurate soil and pipe parameters and the lack of consideration of external loads.

Morphology-dependent wrinkled silica-supported Pd catalysts for hydrogenation of furfural under mild conditions

The production of tetrahydrofurfuryl alcohol (THFAL) from biomass-derived furfural (FF) via one-pot hydrogenation is challenging owing to the high hydrogen pressure and temperature requirements of the system. In this study, a hydrothermal method is used to synthesize a series of wrinkled silica (KCC-1) supports having different morphologies and textural properties by modulating the cetylpyridinium bromide hydrate (CPB)/tetraethyl orthosilicate (TEOS) ratio. Subsequently, Pd-supported KCC-1 catalysts are fabricated along with a Pd/SiO2 catalyst (for comparative studies) via a chemical reduction method. Interestingly, the morphological features of the supports, such as the specific surface area, pore size, and Pd anchoring sites, differed significantly for different CPB/TEOS ratios. Among the synthesized catalysts, Pd/KCC 0.3, with the lowest proportion of Pd nanoparticles deposited on the external porous surface, exhibits the highest catalytic activity, owing to its large specific surface area and moderate pore size. Moreover, it shows the highest FF conversion of 100% and THFAL selectivity of 85% in 6 h at 50 °C under 20 bar H2.

Enhanced production and control of liquid alkanes in the hydrogenolysis of polypropylene over shaped Ru/CeO2 catalysts

The hydrogenolysis of polypropylene waste to liquid hydrocarbons offers a promising pathway for the chemical recycling of waste polymers. This work describes the importance of reaction conditions and support morphology to produce high liquid yields with enhanced control of chain length over highly active shaped and non-shaped Ru/CeO2 catalysts. The shaped 2 wt% Ru/CeO2 exhibit high liquid alkane yields (58–81%) when compared to the non-shaped 2 wt% Ru/CeO2 (liquid yield: 34–58%) under optimized reaction conditions (220 °C, 16 h, 30 bar H2). In particular, the 2 wt% Ru/CeO2 nanocube catalyst exhibits the highest activity yielding lighter hydrocarbons. This was rationalized to be a combination of small Ru cluster formation and enhanced metal-support interactions. The influence of larger Ru particles (≥1.5 nm) was confirmed mechanistically using a computational density functional theory study on the hydrogenolysis of pentane (C5) to determine the favorable formation of methane in the non-shaped Ru/CeO2 catalyst.

Promoting effect of titanium on C―O hydrogenolysis of erythritol to 1,4-butanediol over Pt/W/Ti-SBA-15 catalysts

The C―O hydrogenolysis of erythritol was investigated using Pt/W/Ti-SBA-15 catalysts (4 wt% Pt, 1 wt% W and Si/Ti molar ratio = 50, 33, 20 and 10). Ti-incorporation enhanced the hydrogenolysis activity and the yield of 1,4-butanediol (1,4-BDO). A catalyst with Si/Ti = 20 afforded erythritol conversion of 94 mol% with 1,4-BDO yield of 32.6 mol% and total BDOs yield of 51.7 mol% at 190 °C, 50 bar H2 and 12 h. For the catalyst with no titanium (Pt/W/SBA-15), a double the time was required to achieve such yield. There observed electronic connectivity amongst Ti, Pt and W. For the catalyst with Si/Ti = 20, a greater amount of interfacial Pt-O-W(Ti) sites with Pt in + 2 oxidation state was present. The enhanced catalytic performance of these catalysts was corresponded to dispersed Pt (that facilitate hydrogen activation and spillover) and acidic interfacial Pt-O-W sites (that promote the adsorption and hydrogenolysis of erythritol to diols).

Iridium Nanoparticles on SPIONs as a Catalyst for N‐Heteroarene and Styrene Hydrogenation Reactions and their DFT Studies

AbstractIn this study, iridium nanoparticles (IrNPs) on superparamagnetic iron oxide nanoparticles (SPIONs) are used to catalyze N‐heteroarene and styrene hydrogenation processes. The IrNP@SPIONs catalyst was fabricated by reducing the Ir‐salt precursors in deionized water on SPIONs (Fe3O4), and its catalytic reactivity for the hydrogenation of N‐heteroarenes and styrene under mild reaction conditions as hydrogen under pressure was evaluated. The catalyst was characterized by FTIR, Raman, XRD, SEM, XPS, ICP‐OES, and TEM. The results showed that IrNPs@SPIONs exhibited >99 % conversion with 1,2,3,4‐tetrahydroquinoline (py‐THQ) selectivity under 30 bar H2 at 100 °C temperature in 24 h using DCM as a solvent. The functional group tolerance of 6‐chloroquinoline demonstrated 99 % chemoselectivity towards the 6‐chloro‐tetrahydroquinoline (6‐Cl‐py‐THQ) formation. The reactivity trend in 2‐, 4‐, and 8‐methylquinoline was evaluated and corroborated with the DFT studies. The catalytic application was extended to the hydrogenation of styrene, which resulted in a 70 % conversion with >99 % ethylbenzene selectivity. The hydrogenation of 2‐bromostyrene produced a 75 % conversion with >99 % chemoselectivity of 2‐bromoethylbenzene.

Advanced in situ IR spectroscopy study of anisole hydrodeoxygenation over Ni/SiO2 catalysts

Hydrodeoxygenation (HDO) of anisole was investigated over Ni/SiO2 catalysts prepared by incipient wetness impregnation (IWI) and deposition–precipitation (DP). The in situ FTIR, temperature-programmed surface reaction (TPSR-MS), as well as high pressure flow reactions were carried out to relate catalyst properties and reaction mechanism. The small-size Ni0-Ni+ species (2.0 nm) in Ni/SiO2-DP catalyst exhibits a strong hydrogenolysis activity for anisole, favouring the formation of phenol and benzene. The demethylation of anisole to phenol is a rapid step compared to the deoxygenation of phenol to benzene as indicated by in situ FTIR studies. The intensity of C–C stretching vibration in the two rings was enhanced with increasing temperature, suggesting the formation of condensed-ring products was promoted by high reaction temperature. The Ni/SiO2-IWI catalyst, which exhibits a larger Ni0 particle size (14.1 nm) and higher amount of desorbed H2 per surface Ni compared to Ni/SiO2-DP, shows a high hydrogenation but low hydrogenolysis activity, towards the formation of methoxycyclohexane under 40 bar H2 pressure flow reaction.

PtIV-Containing Hexaplatinate(II) [PtIVPtII6O6(AsO2(CH3)2)6]2- and Hexapalladate(II) [PtIVPdII6O6(AsO2(CH3)2)6]2.

The first PtIV-containing discrete polyoxoplatinate(II) [PtIVPtII6O6(AsO2(CH3)2)6]2- (Pt7) and polyoxopalladate(II) [PtIVPdII6O6(AsO2(CH3)2)6]2- (PtPd6) have been prepared and characterized in the solid state, in solution, and in the gas phase. The molecular structures of the noble metal-oxo clusters Pt7 and PtPd6 comprise a central, octahedral PtIVO6 hetero group surrounded by six square-planar MO4 (M = PtII, PdII) units, which are capped by six dimethylarsinate ligands. The polyanions were prepared under simple one-pot aqueous solution conditions by reacting H2Pt(OH)6 with either K2PtCl4 or Pd(NO3)2 in sodium dimethylarsinate buffer (pH 7) at 80 °C. Catalytic studies were performed on Pt7 supported on SBA15-apts for o-xylene hydrogenation at 300 °C and 90 bar H2 pressure and indicated excellent activity and recyclability with low activation temperature.

Performance of Polymer Electrolyte Membrane Water Electrolysis Systems: Configuration, Stack Materials, Turndown and Efficiency

A cell model is developed and validated to analyze the performance of polymer electrolyte membrane water electrolysis (PEMWE) stacks and systems. It is used to characterize the oxygen evolution reaction (OER) activity on a TiO2-supported IrO2 catalyst and an unsupported IrO2 powder catalyst. Electrochemical, stack, and system thermoneutral potentials are defined and determined for isothermal and non-isothermal stack operation. Conditions are determined under which the system thermoneutral potential or flammability of H2 in the O2 anode stream limits the stack turndown and operating temperature. Performance is analyzed of a complete PEMWE system with an electrolyzer stack containing an IrO2/TiO2 anode catalyst (2 mg/cm2 Ir loading) and N117-like membrane mitigated for H2 crossover, anode balance-of-plant (BOP) components, cathode BOP system with temperature swing adsorption for H2 purification, and electrical BOP system with transformer and rectifier. At the rated power condition, defined as 2 A/cm2 at 1.9 V, 80 °C, and 30 bar H2 pressure, the stack/system efficiency is 65.3%/60.3% at beginning of life (BOL), decreasing to 59.3%/53.9% at end of life (EOL). The peak stack/system efficiency is 76.3%/70.2% at BOL, decreasing to 71.2%/65.6% at EOL. Improvements in catalyst activity and membrane are identified for a 50% increase in current to 3 A/cm2 at 1.8 V.

A reusable, impurity-tolerant and noble metal-free catalyst for hydrocracking of waste polyolefins.

One-step conversion of low-purity polyolefins to value-added products without pretreatments represents a great opportunity for chemical recycling of waste plastics. However, additives, contaminants, and heteroatom-linking polymers tend to be incompatible with catalysts that break down polyolefins. Here, we disclose a reusable, noble metal-free and impurity-tolerant bifunctional catalyst, MoSx-Hbeta, for hydroconversion of polyolefins into branched liquid alkanes under mild conditions. The catalyst works for a wide scope of polyolefins, including different kinds of high-molecular weight polyolefins, polyolefins mixed with various heteroatom-linking polymers, contaminated polyolefins, and postconsumer polyolefins with/without cleaning under 250°C and 20 to 30 bar H2 in 6 to 12 hours. A 96% yield of small alkanes was successfully achieved even at a temperature as low as 180°C. These results demonstrate the great potentials of hydroconversion in practical use of waste plastics as a largely untapped carbon feedstock.

A two-stage strategy for upcycling chlorine-contaminated plastic waste

AbstractChemical upcycling of polyolefin plastic waste to lubricant, wax and fuel-range hydrocarbons over metal-based catalysts is a crucial technological solution to the enormous environmental threat posed by plastic waste. However, currently available methods are incompatible with chlorine-contaminated feedstocks. Here we report a two-stage strategy for upcycling chlorine-contaminated polypropylene. First, magnesia–alumina mixed oxide at 30 bar H2 and 250 °C serves as a chlorine trap by rapidly forming solid chloride, resulting in nearly complete chlorine extraction from the polyolefin melt. This enables the upcycling of plastic waste with up to 10% polyvinyl chloride content to lubricants over ruthenium-based catalysts, in the second stage. The strategy is also applicable to chlorinated aromatics and alkanes. The proposed strategy renders hydrocracking and hydrogenolysis catalysts less sensitive to the chlorine impurities in feedstocks while eliminating HCl emissions and chlorine contamination in products. It could incentivize further progress in plastics upcycling.

Selective Hydrodeoxygenation of Guaiacol to Cyclohexane over Ru-Catalysts Based on MFI Nanosheets

Bio-oils derived from the pyrolysis of lignin-based biomass often contain a variety of oxygenated compounds, which can compromise their usefulness as a fuel. To improve the quality of bio-oil, catalytic hydrodeoxygenation (HDO) is a crucial step that removes oxygen from the oil in the form of water. In this study, we showed that MFI nanosheets are excellent supports for Ru-catalysts. We synthesized highly crystalline MFI nanosheets using a simple hydrothermal seeding procedure; the final material was obtained in 56 h of crystallization. We investigated the activity of Ru supported on different materials. Our findings indicated that Ru supported on hierarchical MFI demonstrated excellent activity in HDO of guaiacol. Our results demonstrated that Ru/ZNS-56 achieved nearly 100% selectivity towards cyclohexane under mild conditions (200 °C, 50 bar H2, 1 h).

Continuous Flow Hydrogenation of Lignin-model Aromatic Compounds over Carbon-supported Noble Metals.

An efficient continuous-flow (CF) protocol was designed for the hydrogenation of lignin-derived aromatics to the corresponding cycloalkanes derivatives. A parametric analysis of the reaction was carried out by tuning the temperature, the H2 pressure and the flow rate, and using diphenyl ether (DPE) as a model substrate, commercial Ru/C as a catalyst, and isopropanol as a solvent: at 25 °C, 50 bar H2, and a flow rate of 0.1 mL min-1, dicyclohexyl ether was achieved in an 86% selectivity, at quantitative conversion. By-products from the competitive C-O bond cleavage of DPE, cyclohexanol and cyclohexane, did not exceed 14% in total. Remarkably, prolonged experiments demonstrated an excellent stability of the catalyst whose performance was unaltered for up to 420 min of time-of-stream. A substrate scope evaluation proved that under the same conditions used for DPE, a variety of substrates including alkoxy-, allyl-, and carbonyl-functionalised phenols, biphenyl, aryl benzyl- and phenethyl ethers (10 examples) yielded the ring-hydrogenated products with selectivity up to 99% at complete conversion.

Effect of degraded environmental conditions on the service behavior of a X65 pipeline steel not designed for hydrogen transport

With the international drive to deploy green energies and decarbonized intermediates in the place of fossil fuel sources, a large number of developed countries are actively preparing for a future where hydrogen plays a strategic role as an energy storage medium. Producing and using hydrogen requires the rapid expansion of a dedicated, economically viable industrial sector. Nevertheless, questions on how to safely store, transport and distribute hydrogen remain an important priority today. In countries with existing natural gas transport grids, the possibility to retrofit these networks to store and transport hydrogen-natural gas blends is being studied.A key challenge is to evaluate how pressurized H2 would interact with steel structures with regards structural embrittlement of the latter, with a view to exploiting existing transport infrastructures for storage and transport applications. In this work, we evaluate the H2-performance of a non-hydrogen service ×65 pipeline steel. The cracking susceptibility of this steel grade has been evaluated at 100 bar H2 using slow strain rate testing, Constant strain testing and fracture toughness measurements. Accompanying hydrogen permeation tests under pressure provide diffusion data and elucidate the discussion. Exposures were carried out in dry or wet H2 and with or without H2S contamination at levels representative of biogas. The results underline that the impact of dry or wet hydrogen on this grade are moderate. The presence of traces of H2S together with humidity could risk seriously degrading the mechanical performance of the ×65 steel grade.

A Sustainable Approach to Selective Hydrogenation of Unsaturated Esters and Aldehydes with Ruthenium Catalysts

AbstractThe reduction of esters and aldehydes to alcohols is an important reaction in the chemical industry to produce a wide range of bulk and fine chemicals. Herein, the unexpected behavior of three state‐of‐the‐art, commercially available Ru‐catalysts for the hydrogenation of these feedstocks is reported. For ester and aldehydes containing a C=C bond, it was possible to carry out the selective hydrogenation of the ester or aldehyde functionality while keeping the C=C double‐bond essentially untouched. Furthermore, it is demonstrated that these substrates can be reduced under very mild reaction conditions (as low as 40 °C and 5 bar of H2) and that anisole, a solvent with a high sustainability rank, is suitable for these catalytic hydrogenations.