Structure-sensitive epoxidation of dicyclopentadiene over TiO2 catalysts

Epoxidation of dicyclopentadiene (DCPD) is studied on a series of TiO₂ catalysts using hydrogen peroxide as an oxidant. DCPD derivatives have applications in several areas including polymer, pharmaceutical and pesticide products. The control of selectivity leading to the desired product is important for many of these applications. Using experimental and computational studies, we show that the surface crystalline phases of TiO₂ play crucial roles not only in the formation of peroxo species but also in the selective epoxidation of two different CC double bonds in DCPD.

Chemical Recycling of Used PET by Glycolysis Using Niobia-Based Catalysts

Plastic production has steadily increased worldwide at a staggering pace. The polymer industry is, unfortunately, C-intensive, and accumulation of plastics in the environment has become a major issue. Plastic waste valorization into fresh monomers for production of virgin plastics can reduce both the consumption of fossil feedstocks and the environmental pollution, making the plastic economy more sustainable. Recently, the chemical recycling of plastics has been studied as an innovative solution to achieve a fully sustainable cycle. In this way, plastics are depolymerized to their monomers or/and oligomers appropriate for repolymerization, closing the loop. In this work, PET was depolymerized to its bis(2-hydroxyethyl) terephthalate (BHET) monomer via glycolysis, using ethylene glycol (EG) in the presence of niobia-based catalysts. Using a sulfated niobia catalyst treated at 573 K, we obtained 100% conversion of PET and 85% yield toward BHET at 195 °C in 220 min. This approach allows recycling of the PET at reasonable conditions using an inexpensive and nontoxic material as a catalyst.

Ti3C2Tx MXene Polymer Composites for Anticorrosion: An Overview and Perspective

As the most studied two-dimensional (2D) material from the MXene family, Ti₃C₂T_x has constantly gained interest from academia and industry. Ti₃C₂T_x MXene has the highest electrical conductivity (up to 24,000 S cm^-1) and one of the highest stiffness values with a Young's modulus of ∼ 334 GPa among water-dispersible conductive 2D materials. The negative surface charge of MXene helps to disperse it well in aqueous and other polar solvents. This solubility across a wide range of solvents, excellent interface interaction, tunable surface functionality, and stability with other organic/polymeric materials combined with the layered structure of Ti₃C₂T_x MXene make it a promising material for anticorrosion coatings. While there are many reviews on Ti₃C₂T_x MXene polymer composites for catalysis, flexible electronics, and energy storage, to our knowledge, no review has been published yet on MXenes' anticorrosion applications. In this brief report, we summarize the current progress and the development of Ti₃C₂T_x polymer composites for anticorrosion. We also provide an outlook and discussion on possible ways to improve the exploitation of Ti₃C₂T_x polymer composites as anticorrosive materials. Finally, we provide a perspective beyond Ti₃C₂T_x MXene composition for the development of future anticorrosion coatings.

Highly active and stable Co (Co3O4)_Sm2O3 nano-crystallites derived from Sm2Co7 and SmCo5 intermetallic compounds in NH3 synthesis and CO2 conversion

Structural and electronic properties of Sm2Co7 and SmCo5 Intermetallic compound derived catalysts in activation of N2 and CO2 molecules.

Control over Electrochemical CO2 Reduction Selectivity by Coordination Engineering of Tin Single-Atom Catalysts

Carbon-based single-atom catalysts (SACs) with well-defined and homogeneously dispersed metal-N4 moieties provide a great opportunity for CO2 reduction. However, controlling the binding strength of various reactive intermediates on catalyst surface is necessary to enhance the selectivity to a desired product, and it is still a challenge. In this work, the authors prepared Sn SACs consisting of atomically dispersed SnN3 O1 active sites supported on N-rich carbon matrix (Sn-NOC) for efficient electrochemical CO2 reduction. Contrary to the classic Sn-N4 configuration which gives HCOOH and H2 as the predominant products, Sn-NOC with asymmetric atomic interface of SnN3 O1 gives CO as the exclusive product. Experimental results and density functional theory calculations show that the atomic arrangement of SnN3 O1 reduces the activation energy for *COO and *COOH formation, while increasing energy barrier for HCOO* formation significantly, thereby facilitating CO2 -to-CO conversion and suppressing HCOOH production. This work provides a new way for enhancing the selectivity to a specific product by controlling individually the binding strength of each reactive intermediate on catalyst surface.

Stepping Stones in CO2 Utilization: Optimizing the Formate to Oxalate Coupling Reaction Using Response Surface Modeling

One of the crucial steps for the conversion of CO₂ into polymers is the catalytic formate to oxalate coupling reaction (FOCR). Formate can be obtained from the (electro)catalytic reduction of CO₂, while oxalate can be further processed toward building blocks for modern plastics. In its 175 year history, multiple parameters for the FOCR have been suggested to be of importance. Yet, no comprehensive understanding considering all those parameters is available. Hence, we aim to assess the relative impact of all those parameters and deduce the optimal reaction conditions for the FOCR. We follow a systematic two-stage approach in which we first evaluate the most suitable categorical variables of catalyst, potential poisons, and reaction atmospheres. In the second stage, we evaluate the impact of the continuous variables temperature, reaction time, catalyst loading, and active gas removal within previously proposed ranges, using a response surface modeling methodology. We found KOH to be the most suitable catalyst, and it allows yields of up to 93%. Water was found to be the strongest poison, and its efficient removal increased oxalate yields by 35%. The most promising reaction atmosphere is hydrogen, with the added benefit of being equal to the gas produced in the reaction. The temperature has the highest impact on the reaction, followed by reaction time and purge rates. We found no significant impact of catalyst loading on the reaction within the ranges reported previously. This research provides a clear and concise multiparameter optimization of the FOCR and provides insight into the reaction cascade involving the formation and decomposition of oxalates from formate.

Towards Sustainable Oxalic Acid from CO2 and Biomass

To quickly and drastically reduce CO2 emissions and meet our ambitions of a circular future, we need to develop carbon capture and storage (CCS) and carbon capture and utilization (CCU) to deal with the CO2 that we produce. While we have many alternatives to replace fossil feedstocks for energy generation, for materials such as plastics we need carbon. The ultimate circular carbon feedstock would be CO2 . A promising route is the electrochemical reduction of CO2 to formic acid derivatives that can subsequently be converted into oxalic acid. Oxalic acid is a potential new platform chemical for material production as useful monomers such as glycolic acid can be derived from it. This work is part of the European Horizon 2020 project "Ocean" in which all these steps are developed. This Review aims to highlight new developments in oxalic acid production processes with a focus on CO2 -based routes. All available processes are critically assessed and compared on criteria including overall process efficiency and triple bottom line sustainability.

Molybdenum Oxide Supported on Ti3AlC2 is an Active Reverse Water-Gas Shift Catalyst

MAX phases are layered ternary carbides or nitrides that are attractive for catalysis applications due to their unusual set of properties. They show high thermal stability like ceramics, but they are also tough, ductile, and good conductors of heat and electricity like metals. Here, we study the potential of the Ti₃AlC₂ MAX phase as a support for molybdenum oxide for the reverse water-gas shift (RWGS) reaction, comparing this new catalyst to more traditional materials. The catalyst showed higher turnover frequency values than MoO₃/TiO₂ and MoO₃/Al₂O₃ catalysts, due to the outstanding electronic properties of the Ti₃AlC₂ support. We observed a charge transfer effect from the electronically rich Ti₃AlC₂ MAX phase to the catalyst surface, which in turn enhances the reducibility of MoO₃ species during reaction. The redox properties of the MoO₃/Ti₃AlC₂ catalyst improve its RWGS intrinsic activity compared to TiO₂- and Al₂O₃-based catalysts.

Monomers from CO2 : Superbases as Catalysts for Formate-to-Oxalate Coupling

Invited for this month's cover are the Industrial Sustainable Chemistry group of Prof. Dr Gert-Jan M. Gruter and the Catalysis Engineering group of Dr. Raveendran Shiju at the University of Amsterdam. The image shows a full cycle from CO₂ to polymers via several steps. The work reports the use of superbases in suitable environments to improve the formate coupling step by drastically lowering the reaction temperature and times whilst achieving higher yields. The Full Paper itself is available at 10.1002/cssc.202002725.

Monomers from CO2 : Superbases as Catalysts for Formate-to-Oxalate Coupling

An interesting contribution to solving the climate crisis involves the use of CO₂ as a feedstock for monomers to produce sustainable plastics. In the European Horizon 2020 project "OCEAN" a continuous multistep process from CO₂ to oxalic acid and derivatives is developed, starting with the electrochemical reduction of CO₂ to potassium formate. The subsequent formate-to-oxalate coupling is a reaction that has been studied and commercially used for over 150 years. With the introduction of superbases as catalysts under moisture-free conditions unprecedented improvements were shown for the formate coupling reaction. With isotopic labelling experiments the presence of carbonite as an intermediate was proven during the reaction, and with a unique operando set-up the kinetics were studied. Ultimately, the required reaction temperature could be dropped from 400 to below 200 °C, and the reaction time could be reduced from 10 to 1 min whilst achieving 99 % oxalate yield.

Butane Dry Reforming Catalyzed by Cobalt Oxide Supported on Ti2 AlC MAX Phase

MAX (Mn+1 AXn ) phases are layered carbides or nitrides with a high thermal and mechanical bulk stability. Recently, it was shown that their surface structure can be modified to form a thin non-stoichiometric oxide layer, which can catalyze the oxidative dehydrogenation of butane. Here, the use of a Ti2 AlC MAX phase as a support for cobalt oxide was explored for the dry reforming of butane with CO2 , comparing this new catalyst to more traditional materials. The catalyst was active and selective to synthesis gas. Although the surface structure changed during the reaction, the activity remained stable. Under the same conditions, a titania-supported cobalt oxide catalyst gave low activity and stability due to the agglomeration of cobalt oxide particles. The Co3 O4 /Al2 O3 catalyst was active, but the acidic surface led to a faster deactivation. The less acidic surface of the Ti2 AlC was better at inhibiting coke formation. Thanks to their thermal stability and acid-base properties, MAX phases are promising supports for CO2 conversion reactions.

Shape-Preserving Chemical Conversion of Architected Nanocomposites

Forging customizable compounds into arbitrary shapes and structures has the potential to revolutionize functional materials, where independent control over shape and composition is essential. Current self-assembly strategies allow impressive levels of control over either shape or composition, but not both, as self-assembly inherently entangles shape and composition. Herein, independent control over shape and composition is achieved by chemical conversion reactions on nanocrystals, which are first self-assembled in nanocomposites with programmable microscopic shapes. The multiscale character of nanocomposites is crucial: nanocrystals (5-50 nm) offer enhanced chemical reactivity, while the composite layout accommodates volume changes of the nanocrystals (≈25%), which together leads to complete chemical conversion with full shape preservation. These reactions are surprisingly materials agnostic, allowing a large diversity of chemical pathways, and development of conversion pathways yielding a wide selection of shape-controlled transition metal chalcogenides (cadmium, manganese, iron, and nickel oxides and sulfides). Finally, the versatility and application potential of this strategy is demonstrated by assembling: 1) a scalable and highly reactive nickel catalyst for the dry reforming of butane, 2) an agile magnetic-controlled particle, and 3) an electron-beam-controlled reversible microactuator with sub-micrometer precision. Previously unimaginable customization of shape and composition is now achievable for assembling advanced functional components.

CO2 Hydrogenation at Atmospheric Pressure and Low Temperature Using Plasma-Enhanced Catalysis over Supported Cobalt Oxide Catalysts

CO₂ is a promising renewable, cheap, and abundant C1 feedstock for producing valuable chemicals, such as CO and methanol. In conventional reactors, because of thermodynamic constraints, converting CO₂ to methanol requires high temperature and pressure, typically 250 °C and 20 bar. Nonthermal plasma is a better option, as it can convert CO₂ at near-ambient temperature and pressure. Adding a catalyst to such plasma setups can enhance conversion and selectivity. However, we know little about the effects of catalysts in such systems. Here, we study CO₂ hydrogenation in a dielectric barrier discharge plasma-catalysis setup under ambient conditions using MgO, γ-Al₂O₃, and a series of Co _x O _y /MgO catalysts. While all three catalyst types enhanced CO₂ conversion, Co _x O _y /MgO gave the best results, converting up to 35% of CO₂ and reaching the highest methanol yield (10%). Control experiments showed that the basic MgO support is more active than the acidic γ-Al₂O₃, and that MgO-supported cobalt oxide catalysts improve the selectivity toward methanol. The methanol yield can be tuned by changing the metal loading. Overall, our study shows the utility of plasma catalysis for CO₂ conversion under mild conditions, with the potential to reduce the energy footprint of CO₂-recycling processes.

An experimental approach for controlling confinement effects at catalyst interfaces

Catalysts are conventionally designed with a focus on enthalpic effects, manipulating the Arrhenius activation energy. This approach ignores the possibility of designing materials to control the entropic factors that determine the pre-exponential factor. Here we investigate a new method of designing supported Pt catalysts with varying degrees of molecular confinement at the active site. Combining these with fast and precise online measurements, we analyse the kinetics of a model reaction, the platinum-catalysed hydrolysis of ammonia borane. We control the environment around the Pt particles by erecting organophosphonic acid barriers of different heights and at different distances. This is done by first coating the particles with organothiols, then coating the surface with organophosphonic acids, and finally removing the thiols. The result is a set of catalysts with well-defined "empty areas" surrounding the active sites. Generating Arrhenius plots with >300 points each, we then compare the effects of each confinement scenario. We show experimentally that confining the reaction influences mainly the entropy part of the enthalpy/entropy trade-off, leaving the enthalpy unchanged. Furthermore, we find this entropy contribution is only relevant at very small distances (<3 Å for ammonia borane), where the "empty space" is of a similar size to the reactant molecule. This suggests that confinement effects observed over larger distances must be enthalpic in nature.

Self-Exfoliated Synthesis of Transition Metal Phosphate Nanolayers for Selective Aerobic Oxidation of Ethyl Lactate to Ethyl Pyruvate

Two-dimensional (2D) transition metal nanosheets are promising catalysts because of the enhanced exposure of the active species compared to their 3D counterparts. Here, we report a simple, scalable, and reproducible strategy to prepare 2D phosphate nanosheets by forming a layered structure in situ from phytic acid (PTA) and transition metal precursors. Controlled combustion of the organic groups of PTA results in interlayer carbon, which keeps the layers apart during the formation of phosphate, and the removal of this carbon results in ultrathin nanosheets with controllable layers. Applying this concept to vanadyl phosphate synthesis, we show that the method yields 2D ultrathin nanosheets of the orthorhombic β-form, exposing abundant V⁴⁺/V⁵⁺ redox sites and oxygen vacancies. We demonstrate the high catalytic activity of this material in the vapor-phase aerobic oxidation of ethyl lactate to ethyl pyruvate. Importantly, these β-VOPO₄ compounds do not get hydrated, thereby reducing the competing hydrolysis reaction by water byproducts. The result has superior selectivity to ethyl pyruvate compared to analogous vanadyl phosphates. The catalysts are highly stable, maintaining a steady-state conversion of ∼90% (with >80% selectivity) for at least 80 h on stream. This "self-exfoliated" synthesis protocol opens opportunities for preparing structurally diverse metal phosphates for catalysis and other applications.

Nanocarbon Catalysts: Recent Understanding Regarding the Active Sites

Although carbon itself acts as a catalyst in various reactions, the classical carbon materials (e.g., activated carbons, carbon aerogels, carbon black, carbon fiber, etc.) usually show low activity, stability, and oxidation resistance. With the recent availability of nanocarbon catalysts, the application of carbon materials in catalysis has gained a renewed momentum. The research is concentrated on tailoring the surface chemistry of nanocarbon materials, since the pristine carbons in general are not active for heterogeneous catalysis. Surface functionalization, doping with heteroatoms, and creating defects are the most used strategies to make efficient catalysts. However, the nature of the catalytic active sites and their role in determining the activity and selectivity is still not well understood. Herein, the types of active sites reported for several mainstream nanocarbons, including carbon nanotubes, graphene-based materials, and 3D porous nanocarbons, are summarized. Knowledge about the active sites will be beneficial for the design and synthesis of nanocarbon catalysts with improved activity, selectivity, and stability.

A Simple and Efficient Device and Method for Measuring the Kinetics of Gas-Producing Reactions

We present a new device for quantifying gases or gas mixtures based on the simple principle of bubble counting. With this device, we can follow reaction kinetics down to volume step sizes of 8–12 μL. This enables the accurate determination of both time and size of these gas quanta, giving a very detailed kinetic analysis. We demonstrate this method and device using ammonia borane hydrolysis as a model reaction, obtaining Arrhenius plots with over 300 data points from a single experiment. Our device not only saves time and avoids frustration, but also offers more insight into reaction kinetics and mechanistic studies. Moreover, its simplicity and low cost open opportunities for many lab applications.

A Critical Look at Direct Catalytic Hydrogenation of Carbon Dioxide to Olefins

One of the main initiatives for fighting climate change is to use carbon dioxide as a resource instead of waste. In this respect, thermocatalytic carbon dioxide hydrogenation to high-added-value chemicals is a promising process. Among the products of this reaction (alcohols, alkanes, olefins, or aromatics), light olefins are interesting because they are building blocks for making polymers, as well as other important chemicals. Olefins are mainly produced from fossil fuel sources, but the increasing demand of plastics boosts the need to develop more sustainable synthetic routes. This review gives a critical overview of the most recent achievements in direct carbon dioxide hydrogenation to light olefins, which can take place through two competitive routes: the modified Fischer-Tropsch synthesis and methanol-mediated synthesis. Both routes are compared in terms of catalyst development, reaction performance, and reaction mechanisms. Furthermore, practical aspects of the commercialization of this reaction, such as renewable hydrogen production and carbon dioxide capture, compression, and transport, are discussed. It is concluded that, to date, the catalysts used in the carbon dioxide hydrogenation reaction give a wide product distribution, which reduces the specific selectivity to lower olefins. More efforts are needed to reach better control of the C/H surface ratio and interactions within the functionalities of the catalyst, as well as understanding the reaction mechanism and avoiding deactivation. Renewable H₂ production and carbon dioxide capture and transport technologies are being developed, although they are currently still too expensive for industrial application.

Highly efficient production of chiral amines in batch and continuous flow by immobilized ω-transaminases on controlled porosity glass metal-ion affinity carrier

In this study, two stereocomplementary ω-transaminases from Arthrobacter sp. (AsR-ωTA) and Chromobacterium violaceum (Cv-ωTA) were immobilized via iron cation affinity binding onto polymer-coated controlled porosity glass beads (EziG™). The immobilization procedure was studied with different types of carrier materials and immobilization buffers of varying compositions, concentrations, pHs and cofactor (PLP) concentrations. Notably, concentrations of PLP above 0.1 mM were correlated with a dramatic decrease of the immobilization yield. The highest catalytic activity, along with quantitative immobilization, was obtained in MOPS buffer (100 mM, pH 8.0, PLP 0.1 mM, incubation time 2 h). Leaching of the immobilized enzyme was not observed within 3 days of incubation. EziG-immobilized AsR-ωTA and Cv-ωTA retained elevated activity when tested for the kinetic resolution of rac-α-methylbenzylamine (rac-α-MBA) in single batch experiments. Recycling studies demonstrated that immobilized EziG3-AsR-ωTA could be recycled for at least 16 consecutive cycles (15 min per cycle) and always affording quantitative conversion (TON ca. 14,400). Finally, the kinetic resolution of rac-α-MBA with EziG3-AsR-ωTA was tested in a continuous flow packed-bed reactor (157 μL reactor volume), which produced more than 5 g of (S)-α-MBA (>49% conversion, >99% ee) in 96 h with no detectable loss of catalytic activity. The calculated TON was more than 110,000 along with a space-time yield of 335 g L-1 h-1.

Highly Selective Oxidation of Ethyl Lactate to Ethyl Pyruvate Catalyzed by Mesoporous Vanadia-Titania

The direct oxidative dehydrogenation of lactates with molecular oxygen is a “greener” alternative for producing pyruvates. Here we report a one-pot synthesis of mesoporous vanadia–titania (VTN), acting as highly efficient and recyclable catalysts for the conversion of ethyl lactate to ethyl pyruvate. These VTN materials feature high surface areas, large pore volumes, and high densities of isolated vanadium species, which can expose the active sites and facilitate the mass transport. In comparison to homogeneous vanadium complexes and VO_x/TiO₂ prepared by impregnation, the meso-VTN catalysts showed superior activity, selectivity, and stability in the aerobic oxidation of ethyl lactate to ethyl pyruvate. We also studied the effect of various vanadium precursors, which revealed that the vanadium-induced phase transition of meso-VTN from anatase to rutile depends strongly on the vanadium precursor. NH₄VO₃ was found to be the optimal vanadium precursor, forming more monomeric vanadium species. V⁴⁺ as the major valence state was incorporated into the lattice of the NH₄VO₃-derived VTN material, yielding more V⁴⁺–O–Ti bonds in the anatase-dominant structure. In situ DRIFT spectroscopy and density functional theory calculations show that V⁴⁺–O–Ti bonds are responsible for the dissociation of ethyl lactate over VTN catalysts and for further activation of the deprotonation of β-hydrogen. Molecular oxygen can replenish the surface oxygen to regenerate the V⁴⁺–O–Ti bonds.

The Ti3 AlC2 MAX Phase as an Efficient Catalyst for Oxidative Dehydrogenation of n-Butane

Dehydrogenation or oxidative dehydrogenation (ODH) of alkanes to produce alkenes directly from natural gas/shale gas is gaining in importance. Ti3 AlC2 , a MAX phase, which hitherto had not been used in catalysis, efficiently catalyzes the ODH of n-butane to butenes and butadiene, which are important intermediates for the synthesis of polymers and other compounds. The catalyst, which combines both metallic and ceramic properties, is stable for at least 30 h on stream, even at low O2 :butane ratios, without suffering from coking. This material has neither lattice oxygens nor noble metals, yet a unique combination of numerous defects and a thin surface Ti1-y Aly O2-y/2 layer that is rich in oxygen vacancies makes it an active catalyst. Given the large number of compositions available, MAX phases may find applications in several heterogeneously catalyzed reactions.

Understanding the oxidative dehydrogenation of ethyl lactate to ethyl pyruvate over vanadia/titania

We studied the vapour-phase oxidative dehydrogenation of ethyl lactate to ethyl pyruvate over V₂O₅/TiO₂ catalysts in a fixed-bed reactor.

Plasma-Assisted Synthesis of Monodispersed and Robust Ruthenium Ultrafine Nanocatalysts for Organosilane Oxidation and Oxygen Evolution Reactions

We report a facile and general approach for preparing ultrafine ruthenium nanocatalysts by using a plasma-assisted synthesis at <100 °C. The resulting Ru nanoparticles are monodispersed (typical size 2 nm) and remain that way upon loading onto carbon and TiO2 supports. This gives robust catalysts with excellent activities in both organosilane oxidation and the oxygen evolution reaction.

Facile Synthesis of a Novel Hierarchical ZSM-5 Zeolite: A Stable Acid Catalyst for Dehydrating Glycerol to Acrolein

Catalytic biomass conversion is often hindered by coking. Carbon compounds cover active surface and plug pores, causing catalyst deactivation. Material design at the nanoscale allows tailoring of the catalytic activity and stability. Here, we report a simple synthesis of nanosized ZSM‐5 materials by using a silicalite‐1 seeding suspension. ZSM‐5 crystals were grown from a deionized silica source in the presence of ammonia. By using silicalite‐1 seeds, crystalline ZSM‐5 is synthesized without any structure‐directing agent. This method allows parallel preparation of a range of ZSM‐5 samples, eliminating time‐consuming ion‐exchange steps. Mesoporosity is introduced by formation of intercrystallite voids, owing to nanocrystal agglomeration. The effects of crystal sizes and morphologies are then evaluated in the catalytic dehydration of glycerol to acrolein, with results compared against commercial ZSM‐5. The most active nanosized ZSM‐5 catalysts were five times more stable compared with commercial ZSM‐5, giving quantitative conversion and twice the acrolein yield compared with the commercial catalyst. The influence of the catalyst structure on the chemical diffusion and the resistance to coking are discussed.

Silica-supported sulfonic acids as recyclable catalyst for esterification of levulinic acid with stoichiometric amounts of alcohols

Converting biomass into value-added chemicals holds the key to sustainable long-term carbon resource management. In this context, levulinic acid, which is easily obtained from cellulose, is valuable since it can be transformed into a variety of industrially relevant fine chemicals. Here we present a simple protocol for the selective esterification of levulinic acid using solid acid catalysts. Silica supported sulfonic acid catalysts operate under mild conditions and give good conversion and selectivity with stoichiometric amounts of alcohols. The sulfonic acid groups are tethered to the support using organic tethers. These tethers may help in preventing the deactivation of the active sites in the presence of water.

Ru/TiO2-catalysed hydrogenation of xylose: the role of the crystal structure of the support

Lattice matching holds the secret to the Ru-catalysed hydrogenation of xylose to xylitol, a key reaction in practical biomass conversion.

Predicting the performance of oxidation catalysts using descriptor models

Mix & match: we show that combining simple heuristic models with experimental validation is an effective method for optimising supported mixed oxide catalysts.

Catalytic acetoxylation of lactic acid to 2-acetoxypropionic acid, en route to acrylic acid

We present an alternative synthetic route to acrylic acid, starting from the platform chemical lactic acid and using heterogeneous catalysis.

Enhanced heterogeneous catalytic conversion of furfuryl alcohol into butyl levulinate

We study the catalytic condensation of furfuryl alcohol with 1-butanol to butyl levulinate. A screening of several commercial and as-synthesized solid acid catalysts shows that propylsulfonic acid-functionalized mesoporous silica outperforms the state-of-the-art phosphotungstate acid catalysts. The catalyst is prepared via template-assisted sol-gel polycondensation of TEOS and MPTMS. It gives 96 % yield (and 100 % selectivity) of butyl levulinate in 4 h at 110 °C. Reaction profiles before and after a hot filtration test confirm that the active catalytic species do not leach into the solution. The catalyst synthesis, characterization, and mode of operation are presented and discussed.

Understanding the solar-driven reduction of CO2 on doped ceria

Surface kinetics and dopant ion migration play a crucial role in the thermocatalytic pathways for converting CO₂ to CO in high-temperature solar-driven reactors using doped cerias.

Organosilane oxidation by water catalysed by large gold nanoparticles in a membrane reactor

Go large! Surprisingly, “large” gold nanoparticles (6–18 nm in diameter) are just as effective as small ones in catalysing the oxidation of organosilanes to silanols. These catalysts are easily separated using ultrafiltration ceramic membranes.

Selective Autooxidation of Ethanol over Titania-Supported Molybdenum Oxide Catalysts: Structure and Reactivity

We study the selective catalytic oxidation of ethanol with air as a sustainable alternative route to acetaldehyde. The reaction is catalysed by molybdenum oxide supported on titania, in a flow reactor under ambient pressure. High selectivity to acetaldehyde (70%-89%, depending on the Mo loading) is obtained at 150 °C. Subsequently, we investigate the structure/performance relationship for various molybdenum oxide species using a combination of techniques including diffuse reflectance UV-visible, infrared, X-ray photoelectron spectroscopies, X-ray diffraction and temperature programmed reduction. As their surface density increases, the monomeric molybdenum oxide species undergo two-dimensional and three-dimensional oligomerisation. This results in polymolybdates and molybdenum oxide crystallites. Importantly, the ethanol oxidation rate depends not only on the overall molybdenum loading and dispersion, but also on the type of molybdenum oxide species prevalent at each surface density and on the domain size. As the molybdenum oxide oligomerisation increases, electron delocalisation becomes easier. This lowers the absorption edge energy and increases the reaction rate.