Hydrodeoxygenation Using Magnetic Induction: High‐Temperature Heterogeneous Catalysis in Solution

Induction Heating for the Electrification of Catalytic Processes

The increasing availability of electrical energy generated from clean, low-carbon, renewable sources like solar and wind power is paving the way for a more sustainable future. This has resulted in a growing trend in the chemical industry to increase the share of electricity use in chemical processes, particularly catalytic ones. This shift towards electrifying catalytic processes offers significant environmental benefits. Current practices rely heavily on fossil fuel-based burners, primarily using natural gas, which contribute significantly to greenhouse gas emissions. Therefore, replacing fossil fuels with electricity can significantly reduce the carbon footprint associated with chemical production. Additionally, the energy-intensive production of metal catalysts used in these processes further exacerbates the environmental impact. This review focuses on the electrification of chemical processes, particularly using induction heating (IH), as a method to reduce the environmental impact of both catalyst production and operation. IH shows promise compared to conventional heating methods, since it offers a cleaner, more efficient, and precise way to heat catalysts in chemical processes by directly generating heat within the catalyst itself. It can potentially even enhance the reaction performance through its influence on the reaction mechanism. By exploring recent advancements in IH-driven catalytic processes, the review delves into how this method is revolutionizing catalysis by enhancing performance, selectivity, and sustainability. It highlights recent breakthroughs and discusses perspectives for further exploration in this rapidly developing field.

Magnetically Induced Catalysis: Definition, Advances, and Potential

The rapidly growing importance of electrification in the chemical industry opens room for disruptive innovations regarding energy input into catalytic processes. Energy efficiency and dynamics of renewable energy supplies represent important challenges, but the design of catalytic systems to cope with such new frameworks may also stimulate the discovery of new catalyst materials and reaction pathways. In this context, many opportunities arise when catalysts are activated in a rapid, localized, and energy-efficient manner. Among the various concepts to achieve adaptivity in catalysis, magnetic induction heating applied directly at the catalyst or in vicinity of the active site has gained increasing attention recently. In this Scientific Perspective, we provide a coherent framework to the emerging field of catalysis using magnetic fields-and in particular alternating current magnetic fields-to activate catalytic materials and define it as magnetically induced catalysis. Promising approaches and selected examples are described to illustrate the scientific concept and to highlight its broad potential for innovation in catalysis from laboratory to industrial scale.

Low pressure amide hydrogenation enabled by magnetocatalysis

The catalytic hydrogenation of amides with molecular hydrogen (H2) is an appealing route for the synthesis of valuable amines entering in the preparation of countless organic compounds. Running effective amide hydrogenation under mild H2 pressures is challenging although desirable to preclude the need for specialized high-pressure technologies in research and industry. Here we show that magnetocatalysis with standard supported catalysts enables unprecedented amide hydrogenation at mild conditions. Widely available and commercial platinum on alumina (Pt/Al2O3) was functionalized with iron carbide nanoparticles (ICNPs) to allow for localized and rapid magnetic induction heating resulting in the activation of neighboring Pt sites by thermal energy transfer. Exposure of the ICNPs@Pt/Al2O3 catalyst to an alternating current magnetic field enables highly active and selective hydrogenation of a range of amides at a reactor temperature of 150 °C under 3 bar or even ambient pressure of H2. ICNPs@Pt/Al2O3 reacts adaptively to fluctuations in electricity supply mimicking the use of intermittent renewable energy sources. This work may pave the way toward a greatly enhanced practicability of amide hydrogenation at the laboratory and production scales, and demonstrates more generally the broad potential of the emerging field of magnetocatalysis for synthetic chemistry.

Magnetically Induced Amination of Alcohols Using MNi@Cu (M=Fe, Co) Nanoparticles as Catalysts

The synthesis of tertiary amines from alcohols (i.e. heptanol, dodecanol, cyclohexanol, benzylalcohol) and secondary amines (Me2NH (DMA), nPr2NH, nBu2NH) has been achieved in one step using trimetallic nanoparticles (NPs) displaying a magnetic core (Co4Ni6 and Fe3Ni7) and a Cu shell as both catalysts and heating agent in the presence of an alternating magnetic field. This methodology limits the redistribution reactions occurring on amines at high temperature leading to both much higher conversion and selectivity in the absence of solvent than usually observed using conventional heating. Moreover, Co4Ni6@Cu NPs were found moisture resistant, thereby allowing for performing the reaction with commercial DMA in water (40 % wt) with again high conversion and selectivity.

Fundamentals and Recent Progress in Magnetic Field Assisted CO2 Capture and Conversion

CO2 capture and conversion technology are highly promising technologies that definitely play a part in the journey towards carbon neutrality. Releasing CO2 by mild stimulation and the development of high efficiency catalytic processes are urgently needed. The magnetic field, as a thermodynamic parameter independent of temperature and pressure, is vital in the enhancement of CO2 capture and conversion process. In this review, the recent progress of magnetic field-enhanced CO2 capture and conversion is comprehensively summarized. The theoretical fundamentals of magnetic field on CO2 adsorption, release and catalytic reduction process are discussed, including the magnetothermal, magnetohydrodynamic, spin selection, Lorentz forces, magnetoresistance and spin relaxation effects. Additionally, a thorough review of the current progress of the enhancement strategies of magnetic field coupled with a variety of fields (including thermal, electricity, and light) is summarized in the aspect of CO2 related process. Finally, the challenges and prospects associated with the utilization of magnetic field-assisted techniques in the construction of CO2 capture and conversion systems are proposed. This review offers a reference value for the future design of catalysts, mechanistic investigations, and practical implementation for magnetic field enhanced CO2 capture and conversion.

TiCl4-mediated deoxygenative reduction of aromatic ketones to alkylarenes with ammonia borane

A rapid and mild protocol for the exhaustive deoxygenation of various aromatic ketones to corresponding alkanes was described, which was mediated by TiCl4 and used ammonia borane (AB) as the reductant. This reduction protocol applies to a wide range of substrates in moderate to excellent yields at room temperature. The gram-scale reaction and syntheses of some key building blocks for SGLT2 inhibitors demonstrated the practicability of this methodology. Preliminary mechanistic studies revealed that the ketone is first converted into an alcohol, which then undergoes a carbocation to give the alkane via hydrogenolysis.

Visible-Light-Induced Nickel-Catalyzed Cross-Coupling of Aryl Bromides with Nitriles

Herein, a visible-light-induced nickel-catalyzed cross-coupling of aryl bromide with nitrile has been reported. By utilization of readily available nitriles as carbonyl precursors, a range of structurally diverse aryl ketones were facilely constructed. The synthetic simplicity, mild reaction conditions, and acidic functional group tolerance would broaden the synthetic utilities of this developed protocol as an expedient alternative to Grignard/organolithium protocols.

Hydrogen Spillover-Driven Dynamic Evolution and Migration of Iron Oxide for Structure Regulation of Versatile Magnetic Nanocatalysts

Magnetic nanocatalysts with properties of easy recovery, induced heating, or magnetic levitation play a crucial role in advancing intelligent techniques. Herein, we report a method for the synthesis of versatile core-shell-type magnetic nanocatalysts through "noncontact" hydrogen spillover-driven reduction and migration of iron oxide with the assistance of Pd. In situ analysis techniques were applied to visualize the dynamic evolution of the magnetic nanocatalysts. Pd facilitates the dissociation of hydrogen molecules into activated H*, which then spills and thus drives the iron oxide reduction, gradual outward split, and migration through the carbonaceous shell. By controlling the evolution stage, nanocatalysts having diverse architectures including core-shell, split core-shell, or hollow type, each featuring Pd or PdFe loaded on the carbon shell, can be obtained. As a showcase, a magnetic nanocatalyst (Pd-loaded split core-shell) can hydrogenate crotonaldehyde to butanal (26 624 h-1 in TOF, ∼100% selectivity), outperforming reported Pd-based catalysts. This is due to the synergy of the enhanced local magnetothermal effect and the preferential adsorption of -C═C on Pd with a small d bandwidth. Another catalyst (PdFe-loaded split core-shell) also delivers a robust performance in phenylacetylene semihydrogenation (100% conversion, 97.5% selectivity) as PdFe may inhibit the overhydrogenation of -C═C. Importantly, not only Pd, other noble metals (e.g., Pt, Ru, and Au) also showed a similar property, revealing a general rule that hydrogen spillover drives the dynamic reduction, splitting, and migration of encapsulated nanosized iron oxide, resulting in diverse structures. This study would offer a structure-controllable fabrication of high-performance magnetic nanocatalysts for various applications.

Induction heating: an efficient methodology for the synthesis of functional core-shell nanoparticles

Induction heating has been applied for a variety of purposes over the years, including hyperthermia-induced cell death, industrial manufacturing, and heterogeneous catalysis. However, its potential in materials synthesis has not been extensively studied. Herein, we have demonstrated magnetic induction heating-assisted synthesis of core-shell nanoparticles starting from a magnetic core. The induction heating approach allows an easy synthesis of FeNi3@Mo and Fe2.2C@Mo nanoparticles containing a significantly higher amount of molybdenum on the surface than similar materials synthesized using conventional heating. Exhaustive electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy characterization data are presented to establish the core-shell structures. Furthermore, the molybdenum shell was transformed into the Mo2C phase, and the catalytic activity of the resulting nanoparticles tested for the propane dry reforming reaction under induction heating. Lastly, the beneficial role of induction heating-mediated synthesis was extended toward the preparation of the FeNi3@WOx core-shell nanoparticles.

Creating and Stabilizing an Oxidized Pd Surface under Reductive Conditions for Photocatalytic Hydrogenation of Aromatic Carbonyls

Photocatalysis provides an eco-friendly route for the hydrogenation of aromatic carbonyls to O-free aromatics, which is an important refining process in the chemical industry that is generally carried out under high pressure of hydrogen at elevated temperatures. However, aromatic carbonyls are often only partially hydrogenated to alcohols, which readily desorbs and are hardly further deoxygenated under ambient conditions. Here, we show that by constructing an oxide surface over the Pd cocatalyst supported on graphitic carbon nitride, an alternative hydrogenation path of aromatic carbonyls becomes available via a step-wise acetalization and hydrogenation, thus allowing efficient and selective production of O-free aromatics. The PdO surface allows for optimum adsorption of reactants and intermediates and rapid abstraction of hydrogen from the alcohol donor, favoring fast acetalization of the carbonyls and their consecutive hydrogenation to O-free hydrocarbons. The photocatalytic hydrogenation of benzaldehyde into toluene shows a high selectivity of >90% and a quantum efficiency of ∼10.2% under 410 nm irradiation. By adding trace amounts of HCl to the reaction solution, the PdO surface remains stable and active for long-term operation at high concentrations, offering perspective for practical applications.

l-Lysine Stabilized FeNi Nanoparticles for the Catalytic Reduction of Biomass-Derived Substrates in Water Using Magnetic Induction

The reduction of biomass-derived compounds gives access to valuable chemicals from renewable sources, circumventing the use of fossil feedstocks. Herein, we describe the use of iron-nickel magnetic nanoparticles for the reduction of biomass model compounds in aqueous media under magnetic induction. Nanoparticles with a hydrophobic ligand (FeNi₃ -PA, PA=palmitic acid) have been employed successfully, and their catalytic performance is intended to improve by ligand exchange with lysine (FeNi₃ -Lys and FeNi₃ @Ni-Lys NPs) to enhance water dispersibility. All three catalysts have been used to hydrogenate 5-hydroxymethylfurfural into 2,5-bis(hydroxymethyl)furan with complete selectivity and almost quantitative yields, using 3 bar of H₂ and a magnetic field of 65 mT in water. These catalysts have been recycled up to 10 times maintaining high conversions. Under the same conditions, levulinic acid has been hydrogenated to γ-valerolactone, and 4'-hydroxyacetophenone hydrodeoxygenated to 4-ethylphenol, with conversions up to 70 % using FeNi₃ -Lys, and selectivities above 85 % in both cases. This promising catalytic system improves biomass reduction sustainability by avoiding noble metals and expensive ligands, increasing energy efficiency via magnetic induction heating, using low H₂ pressure, and proving good reusability while working in an aqueous medium.

One-Pot Synthesis of Diaryl 1,2-Diketones via Zn-Mediated Reductive Coupling

A reductive coupling reaction was established for the synthesis of diaryl 1,2-dicarbonyl compounds from aryl methyl ketones in good yields. The mechanistic study showed the reaction undergoes C(CO)-C(sp³) bond cleavage, with the reductive coupling reaction occurring through an electron transfer process. Notably, the reaction not only is simple to operate but also has mild reaction conditions and a wide range of applicable substrates.

Electrochemical deoxygenative reduction of ketones

Electrochemical reduction via paired electrolysis has been used to achieve deoxygenative reduction of ketones. As a result of the complexing of ketones with the triphenylphosphine radical cation generated by anodic oxidation, the reduction of carbonyl groups occurs readily. Through spontaneous β-scission of phosphoranyl radicals, C-O bonds are cleaved to form benzylic radical intermediates. These radical species are either able to abstract hydrogen from MeCN or undergo reduction at the cathode to give carbanions, upon workup forming reductive hydrogenation of ketones.

Magnetically Induced Catalytic Reduction of Biomass-Derived Oxygenated Compounds in Water

The development of energetically efficient processes for the aqueous reduction of biomass-derived compounds into chemicals is key for the optimal transformation of biomass. Herein we report an early example of the reduction of biomass-derived oxygenated compounds in water by magnetically induced catalysis. Non-coated and carbon-coated core-shell FeCo@Ni magnetic nanoparticles were used as the heating agent and the catalyst simultaneously. In this way it was possible to control the product distribution by adjusting the field amplitude applied during the magnetic catalysis, opening a precedent for this type of catalysis. Finally, the encapsulation of the magnetic nanoparticles in carbon (FeCo@Ni@C) strongly improved the stability of the magnetic catalyst in solution, making its reuse possible up to at least eight times in dioxane and four times in water.

Commercial Cu2 Cr2 O5 Decorated with Iron Carbide Nanoparticles as a Multifunctional Catalyst for Magnetically Induced Continuous-Flow Hydrogenation of Aromatic Ketones

Copper chromite is decorated with iron carbide nanoparticles, producing a magnetically activatable multifunctional catalytic system. This system (ICNPs@Cu2 Cr2 O5 ) can reduce aromatic ketones to aromatic alcohols when exposed to magnetic induction. Under magnetic excitation, the ICNPs generate locally confined hot spots, selectively activating the Cu2 Cr2 O5 surface while the global temperature remains low (≈80 °C). The catalyst selectively hydrogenates a scope of benzylic and non-benzylic ketones under mild conditions (3 bar H2 , heptane), while ICNPs@Cu2 Cr2 O5 or Cu2 Cr2 O5 are inactive when the same global temperature is adjusted by conventional heating. A flow reactor is presented that allows the use of magnetic induction for continuous-flow hydrogenation at elevated pressure. The excellent catalytic properties of ICNPs@Cu2 Cr2 O5 for the hydrogenation of biomass-derived furfuralacetone are conserved for at least 17 h on stream, demonstrating for the first time the application of a magnetically heated catalyst to a continuously operated hydrogenation reaction in the liquid phase.

Self-Limitations of Heat Release in Coupled Core-Shell Spinel Ferrite Nanoparticles: Frequency, Time, and Temperature Dependencies

We explored a series of highly uniform magnetic nanoparticles (MNPs) with a core-shell nanoarchitecture prepared by an efficient solvothermal approach. In our study, we focused on the water dispersion of MNPs based on two different CoFe2O4 core sizes and the chemical nature of the shell (MnFe2O4 and spinel iron oxide). We performed an uncommon systematic investigation of the time and temperature evolution of the adiabatic heat release at different frequencies of the alternating magnetic field (AMF). Our systematic study elucidates the nontrivial variations in the heating efficiency of core-shell MNPs concerning their structural, magnetic, and morphological properties. In addition, we identified anomalies in the temperature and frequency dependencies of the specific power absorption (SPA). We conclude that after the initial heating phase, the heat release is governed by the competition of the Brown and Néel mechanism. In addition, we demonstrated that a rational parameter sufficiently mirroring the heating ability is the mean magnetic moment per MNP. Our study, thus, paves the road to fine control of the AMF-induced heating by MNPs with fine-tuned structural, chemical, and magnetic parameters. Importantly, we claim that the nontrivial variations of the SPA with the temperature must be considered, e.g., in the emerging concept of MF-assisted catalysis, where the temperature profile influences the undergoing chemical reactions.

Stable Iron Oxide Nanoflowers with Exceptional Magnetic Heating Efficiency: Simple and Fast Polyol Synthesis

Magnetically induced hyperthermia has reached a milestone in medical nanoscience and in phase III clinical trials for cancer treatment. As it relies on the heat generated by magnetic nanoparticles (NPs) when exposed to an external alternating magnetic field, the heating ability of these NPs is of paramount importance, so is their synthesis. We present a simple and fast method to produce iron oxide nanostructures with excellent heating ability that are colloidally stable in water. A polyol process yielded biocompatible single core nanoparticles and nanoflowers. The effect of parameters such as the precursor concentration, polyol molecular weight as well as reaction time was studied, aiming to produce NPs with the highest possible heating rates. Polyacrylic acid facilitated the formation of excellent nanoheating agents iron oxide nanoflowers (IONFs) within 30 min. The progressive increase of the size of the NFs through applying a seeded growth approach resulted in outstanding enhancement of their heating efficiency with intrinsic loss parameter up to 8.49 nH m² kg_Fe^-1. The colloidal stability of the NFs was maintained when transferring to an aqueous solution via a simple ligand exchange protocol, replacing polyol ligands with biocompatible sodium tripolyphosphate to secure the IONPs long-term colloidal stabilization.

Determination of the surface temperature of magnetically heated nanoparticles using a catalytic approach

Herein we describe a new method for the determination of the surface temperature of magnetically heated nanoparticles in solution using the temperature dependency of the catalytic performances of iron carbide nanoparticles coated with ruthenium (Fe_2.2C@Ru) for acetophenone hydrodeoxygenation. A correlation between nanoparticle surface temperature and magnetic field could be established. Very high surface temperatures could be estimated in different solvents, which were also found similar at a given magnetic field and well above some solvent boiling points.

Metal-Organic Framework-Confined Single-Site Base-Metal Catalyst for Chemoselective Hydrodeoxygenation of Carbonyls and Alcohols

Chemoselective deoxygenation of carbonyls and alcohols using hydrogen by heterogeneous base-metal catalysts is crucial for the sustainable production of fine chemicals and biofuels. We report an aluminum metal-organic framework (DUT-5) node support cobalt(II) hydride, which is a highly chemoselective and recyclable heterogeneous catalyst for deoxygenation of a range of aromatic and aliphatic ketones, aldehydes, and primary and secondary alcohols, including biomass-derived substrates under 1 bar H₂. The single-site cobalt catalyst (DUT-5-CoH) was easily prepared by postsynthetic metalation of the secondary building units (SBUs) of DUT-5 with CoCl₂ followed by the reaction of NaEt₃BH. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy (XANES) indicated the presence of Co^II and Al^III centers in DUT-5-CoH and DUT-5-Co after catalysis. The coordination environment of the cobalt center of DUT-5-Co before and after catalysis was established by extended X-ray fine structure spectroscopy (EXAFS) and density functional theory. The kinetic and computational data suggest reversible carbonyl coordination to cobalt preceding the turnover-limiting step, which involves 1,2-insertion of the coordinated carbonyl into the cobalt-hydride bond. The unique coordination environment of the cobalt ion ligated by oxo-nodes within the porous framework and the rate independency on the pressure of H₂ allow the deoxygenation reactions chemoselectively under ambient hydrogen pressure.

Bimetallic Nanoparticles Associating Noble Metals and First-Row Transition Metals in Catalysis

Bimetallic nanoparticles (NPs) are complex systems with properties that far exceed those of the individual constituents. In particular, association of a noble metal and a first-row transition metal are attracting increasing interest for applications in catalysis, electrocatalysis, and magnetism, among others. Such objects display a rich structural chemistry thanks to their ability to form intermetallic phases, random alloys, or core-shell species. However, under reaction conditions, the surface of these nanostructures may be modified due to migration, segregation, or isolation of single atoms, leading to the formation of original structures with enhanced catalytic activity. In this respect, Zakhtser et al. report in this issue of ACS Nano the synthesis and study of the chemical evolution of the surface of a series of PtZn nanostructured alloys. In this Perspective, we report some selected examples of bimetallic nanocatalysts and their increased activity compared to that of the corresponding pure noble metal, with a special focus on Pt-based systems. We also discuss the mobility of the species present on the catalyst surface and the electronic influence of one metal to the other.

Realizing Catalytic Acetophenone Hydrodeoxygenation with Palladium-Equipped Porous Organic Polymers

Porous organic polymers (POPs) constructed through covalent bonds have raised tremendous research interest because of their suitability to develop robust catalysts and their successful production with improved efficiency. In this work, we have designed and explored the properties and catalytic activity of a template-free-constructed, hydroxy (-OH) group-enriched porous organic polymer (Ph-POP) bearing functional Pd nanoparticles (Pd-NPs) by one-pot condensation of phloroglucinol (1,3,5-trihydroxybenzene) and terephthalaldehyde followed by solid-phase reduction with H₂. The encapsulated Pd-NPs rested within well-defined POP nanocages and remained undisturbed from aggregation and leaching. This polymer hybrid nanocage Pd@Ph-POP is found to enable efficient liquid-phase hydrodeoxygenation (HDO) of acetophenone (AP) with high selectivity (99%) of ethylbenzene (EB) and better activity than its Pd@Al₂O₃ counterpart. Our investigation demonstrates a facile, scalable, catalyst-template-free methodology for developing novel porous organic polymer catalysts and next-generation efficient greener chemical processes from platform molecules to produce value-added chemicals. With the aid of comprehensive in situ ATR-IR spectroscopy experiments, it is suggested that EB can be more easily desorbed in a solution, reflecting from the much weaker but better-resolved signal at 1494 cm^-1 in Pd@Ph-POP compared to that in Pd@Al₂O₃, which is the key determining factor in favoring an efficient catalytic mechanism. Density functional theory (DFT) calculations were performed to illustrate the detailed reaction network and explain the high catalytic activity observed for the fabricated Pd@Ph-POP catalyst in the HDO conversion of AP to EB. All of the hydrogenation routes, including direct hydrogenation by surface hydrogen, hydrogen transfer, and the keto-enol pathway, are evaluated, providing insights into the experimental observations. The presence of phenolic hydroxyl groups in the Ph-POP frame structure facilitates the hydrogen-shuttling mechanism for dehydration from the intermediate phenylethanol, which was identified as a crucial step for the formation of the final product ethylbenzene. Besides, weaker binding of the desired product ethylbenzene and lower coverage of surface hydrogen atoms on Pd@Ph-POP both contributed to inhibiting the overhydrogenation reaction and explained well the high yield of EB produced during the HDO conversion of AP on Pd@Ph-POP in this study.

Magnetically Induced CO2 Methanation Using Exchange-Coupled Spinel Ferrites in Cuboctahedron-Shaped Nanocrystals

Magnetically induced catalysis can be promoted taking advantage of optimal heating properties from the magnetic nanoparticles to be employed. However, when unprotected, these heating agents that are usually air-sensitive, get sintered under the harsh catalytic conditions. In this context, we present, to the best of our knowledge, the first example of air-stable magnetic nanoparticles that: 1) show excellent performance as heating agents in the CO₂ methanation catalyzed by Ni/SiRAlOx, with CH₄ yields above 95 %, and 2) do not sinter under reaction conditions. To attain both characteristics we demonstrate, first the exchange-coupled magnetic approach as an alternative and effective way to tune the magnetic response and heating efficiency, and second, the chemical stability of cuboctahedron-shaped core-shell hard CoFe₂ O₄ -soft Fe₃ O₄ nanoparticles.

Ultrastable Magnetic Nanoparticles Encapsulated in Carbon for Magnetically Induced Catalysis

Magnetically induced catalysis using magnetic nanoparticles (MagNPs) as heating agents is a new efficient method to perform reactions at high temperatures. However, the main limitation is the lack of stability of the catalysts operating in such harsh conditions. Normally, above 500 °C, significant sintering of MagNPs takes place. Here we present encapsulated magnetic FeCo and Co NPs in carbon (Co@C and FeCo@C) as an ultrastable heating material suitable for high-temperature magnetic catalysis. Indeed, FeCo@C or a mixture of FeCo@C:Co@C (2:1) decorated with Ni or Pt-Sn showed good stability in terms of temperature and catalytic performances. In addition, consistent conversions and selectivities regarding conventional heating were observed for CO₂ methanation (Sabatier reaction), propane dehydrogenation (PDH), and propane dry reforming (PDR). Thus, the encapsulation of MagNPs in carbon constitutes a major advance in the development of stable catalysts for high-temperature magnetically induced catalysis.

Selective Hydrogenation and Hydrodeoxygenation of Aromatic Ketones to Cyclohexane Derivatives Using a Rh@SILP Catalyst

Rhodium nanoparticles immobilized on an acid‐free triphenylphosphonium‐based supported ionic liquid phase (Rh@SILP(Ph₃‐P‐NTf₂)) enabled the selective hydrogenation and hydrodeoxygenation of aromatic ketones. The flexible molecular approach used to assemble the individual catalyst components (SiO₂, ionic liquid, nanoparticles) led to outstanding catalytic properties. In particular, intimate contact between the nanoparticles and the phosphonium ionic liquid is required for the deoxygenation reactivity. The Rh@SILP(Ph₃‐P‐NTf₂) catalyst was active for the hydrodeoxygenation of benzylic ketones under mild conditions, and the product distribution for non‐benzylic ketones was controlled with high selectivity between the hydrogenated (alcohol) and hydrodeoxygenated (alkane) products by adjusting the reaction temperature. The versatile Rh@SILP(Ph₃‐P‐NTf₂) catalyst opens the way to the production of a wide range of high‐value cyclohexane derivatives by the hydrogenation and/or hydrodeoxygenation of Friedel–Crafts acylation products and lignin‐derived aromatic ketones.

Hydro(deoxygenation) Reaction Network of Lignocellulosic Oxygenates

Hydrodeoxygenation (HDO) is a key transformation step to convert lignocellulosic oxygenates into drop-in and functional high-value hydrocarbons through controlled oxygen removal. Nevertheless, the mechanistic insights of HDO chemistry have been scarcely investigated as opposed to a significant extent of hydrodesulfurization chemistry. Current requirements emphasize certain underexplored events of HDO of oxygenates, which include 1) interactions of oxygenates of varied molecular size with active sites of the catalysts, 2) determining the conformation of oxygenates on the active site at the point of interaction, and 3) effects of oxygen contents of oxygenates on the reaction rate of HDO. It is realized that the molecular interactions of oxygenates with the surface of the catalyst dominates the degree and nature of deoxygenation to derive products with desired selectivity by overcoming complex separation processes in a biorefinery. Those oxygenates with high carbon numbers (>C10), multiple furan rings, and branched architectures are even more complex to understand. This article aims to focus on concise mechanistic analysis of biorefinery oxygenates (C_10-35 ) for their deoxygenation processes, with a special emphasis on their interactions with active sites in a complex chemical environment. This article also addresses differentiation of the mode of interactions based on the molecular size of oxygenates. Deoxygenation processes coupled with or without ring opening of furan-based oxygenates and site-substrate cooperativity dictate the formation of diverse value-added products. Oxygen removal has been the key step for microbial deoxygenation by the use of oxygen-removing decarbonylase enzymes. However, challenges to obtain branched and long-chain hydrocarbons remain, which require special attention, including the invention of newer techniques to upgrade the process for combined depolymerization-HDO from real biomass.

The potential of magnetic heating for fabricating Pickering-emulsion-based capsules

Pickering emulsions (particle-stabilized emulsions) have been widely explored due to their potential applications, one of which is using them as precursors for the formation of colloidal capsules that could be utilized in, among others, the pharmacy and food industries. Here, we present a novel approach to fabricating such colloidal capsules by using heating in the alternating magnetic field. When exposed to the alternating magnetic field, magnetic particles, owing to the hysteresis and/or relaxation losses, become sources of nano- and micro-heating that can significantly increase the temperature of the colloidal system. This temperature rise was evaluated in oil-in-oil Pickering emulsions stabilized by both magnetite and polystyrene particles. When a sample reached high enough temperature, particle fusion caused by glass transition of polystyrene was observed on surfaces of colloidal droplets. Oil droplets covered with shells of fused polystyrene particles were proved to be less susceptible to external stress, which can be evidence of the successful formation of capsules from Pickering emulsion droplets as templates.

Promoting heterogeneous catalysis beyond catalyst design

Despite the indisputable success of conventional approaches to manipulate the performance of heterogeneous catalysts by tuning the composition and structure of active sites, future research on catalysis engineering will likely go beyond the catalyst itself. Recently, several auxiliary promotion methods, either promoting the activity of reagents or enabling optimized adsorbate-catalyst interactions, have been proven as viable strategies to enhance catalytic reactions. Those auxiliary promotion methods range from electric/magnetic fields and electric potentials to mechanic stress, significantly altering the properties of reagent molecules and/or the surface characteristics of nanostructured catalysts. Apart from static enhancement effects, they in principle also allow for spatially and temporally variable modifications of catalyst surfaces. While some of those methods have been demonstrated, some are only theoretically predicted, opening exciting avenues for future experimental advances. Besides fundamental descriptions and comparisons of each activation method, in this perspective we plan to provide examples for the applications of those techniques for a variety of catalytic reactions as diverse as N₂ and CO₂ hydrogenation as well as electrochemical water splitting. Finally, we provide a unifying view and guidelines for future research into the use of promotion methods, generating deeper understanding of the complex dynamics on the nanoparticle surface under auxiliary promotion and the expansion of auxiliary techniques to different sustainability-related reactions.