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MXenes are a new family of 2D carbides or nitrides that have attracted attention due to their layered structure, tunable surface groups and high electrical conductivity. Here, we report for the first time that Ti 2 CT x MXene catalyses the selective oxidative dehydrogenation of n -butane to butenes and 1,3-butadiene. This catalyst showed higher intrinsic activity compared to commercial TiC and TiO 2 samples in terms of C 4 olefin formation rate. We propose that the stabilisation of structural vacancies and the change in composition (from a carbide to a mixed phase oxide) in the MXene causes its higher catalytic activity. These vacancies can lead to a higher concentration of unpaired electrons in the MXene-derived material, enhancing its nucleophilic properties and favouring the production of olefins. We thank the Netherlands Organization for Scientific Research (NWO) for the grant “Developing novel catalytic materials for converting CO2, methane and ethane to high-value chemicals in a hybrid plasma-catalytic reactor” (China.15.119). EVRF thanks the “Ministerio de Ciencia e innovación” grant (PID2020-116998RB-I00).

The following sections are included:IntroductionBenefits of computational experimentsNanoporous materialsPore system of a materialStructure modelsThe unit cellStructure file formatsWhere can you find zeolite and MOF structural information?Periodic boundary conditions and the minimum-image conventionForce fieldsRunning a simulationUnits and conversionsOutlineStructural PropertiesEnergy landscapesCharacterization of the pore system of a materialSurface areas, pore volume and pore-size distributionsMolecular Mechanics (MM)Monte Carlo (MC) and AdsorptionBasicsNVT ensembleAdsorption: Gibbs and grand-canonical ensembleEnthalpy of adsorptionMixture adsorption simulationsIdeal Adsorbed Solution Theory (IAST)Molecular Dynamics (MD) and DiffusionNewton’s equations of motionThermo- and barostatsRadial distribution functionsDynamic correlation functionsMean-squared displacement and single component diffusionActivation energyFree energy analysis and dc-TSTSelectivityBreakthrough Simulation of Fixed-bed Separation DevicesIntroductionModeling the fixed-bedConclusionAcknowledgementsReferencesAppendix: RASPA Input for Computing Adsorption and Diffusion PropertiesIntroductionForce field files for CO2 and CH4 in zeolitespseudo atoms.def atom definition fileCO2.def molecule filemethane.def molecule filenitrogen.def molecule fileITQ-29.cif framework definition fileforce field mixing rules.def force field definition fileBlocked pocket definitionsStructural properties of ITQ-29Surface areaVoid-fractionPore-size distributionMinimization of CO2 in ITQ-29Gibbs single component adsorption of CO2 in ITQ-29 using CBMCCO2 single component adsorption using CBMCCH4 single component adsorption using CBMCMixture adsorption of CO2/CH4 in ITQ-29Mixture adsorption of CO2/CH4 in ITQ-29 using CBMCDynamical properties of CO2 and CH4 in ITQ-29MSD, VACF, and RDF of CH4 in ITQ-29 using MDFree energy profiles of CH4 in ITQ-29 at 300 K and 4 molecules per cavity

The following sections are included:IntroductionDensitiesGas AdsorptionSome Tips, Examples, and General Remarks on Adsorption MeasurementsMercury PorosimetryIntroductionMethod and theoryContact angle θSurface tension γSurface area calculationsParticle size determinationDensities obtained from mercury porosimetryCompressibilityHysteresis, pore connectivity, entrapment and snap-offInkbottle poresScanning or waiting for equilibriumInfluence of measuring speed on the resultQuality of the mercuryCleanness of the sampleCleanness of the sample holderSize of the sample holderSafety precautions and working environments for safe handling of mercuryReferences

P.O. thanks the Spanish Ministry of Science, Innovation and Universities (Project MCIU-19-RTI2018-094218-BI00).

In Podzols, organic matter (OM) is stabilized mainly by interaction with minerals, as a direct consequence of pedogenic processes. Metal-organic associations strongly affect OM surface features, particularly microporosity. Cemented ortstein horizons (CM) may form during podzolization, accompanied by a spatial arrangement of OM on mineral surfaces, which differs from that in non-cemented horizons (N-CM). To investigate the metal-organic associations and their changes during pedogenesis, we selected both N-CM and CM podzolic horizons, isolated NaClO-resistant OM and compared the specific surface area (SSA) before and after OM oxidation. The SSA was assessed by using N-2, to detect the pores in the range of micropores (< 2 nm) and mesopores (2-50 nm), and CO2, to measure a smaller microporosity (< 0.5 nm), which is not accessible to N-2. Only the N-CM samples showed the typical increase in N-2-SSA after the removal of labile OM, while a decrease was found in all CM horizons. The CO2-SSA revealed a large number of small micropores characterizing OM, both before and after oxidation. The smallest micropore classes (< 0.5 nm) were, however, more abundant in NaClO-resistant OM, which had therefore a larger number of N-2-inaccessible surfaces than the labile pool. The N-2-SSA data thus indicated a more homogeneous coverage of mineral surfaces by stabilized OM in CM samples. Because of the abundance of small micropores, OM in these podzolic B horizons had extremely large CO2-SSA values (about 800 m(2) g(-1)), with sharp differences between the NaClO-labile OM (290-380 m(2) g(-1)) and the NaClO-stabilized pool (1380-1860 m(2) g(-1)), thus indicating very reactive illuvial organic materials.

Copper immobilized on a functionalized silica support is a good catalyst for the homocoupling of terminal alkynes. The so-called Glaser-Hay coupling reaction can be run in air with catalytic amounts of base. The copper catalyst is active for multiple substituted alkynes, in both polar and non-polar solvents, with good to excellent yields (75-95%). Depending on the alkyne, full conversion can be achieved within 3-24 h. The catalyst was characterized by TGA, inductively coupled plasma and X-ray photoelectron spectroscopy. Leaching tests confirm that the catalyst is and remains heterogeneous. Importantly, the overall reaction requires only alkyne and oxygen (in this case, air) as reagents, making this a clean catalytic oxidative coupling reaction. Copyright (C) 2012 John Wiley & Sons, Ltd.

The catalytic dehydration of glycerol to acrolein is investigated over silica-supported niobia catalysts in a continuous fixed-bed gas-phase reactor. Various supported niobia catalysts are prepared and characterized using surface analysis and spectroscopic methods (XRD, UV-Vis, XPS, N2 adsorption), as well as with ammonia adsorption microcalorimetry. Good results are obtained with initial glycerol conversions of over 70% and with 50-70% selectivity to acrolein. We investigate the influence of changing the catalyst acid strength by varying the niobia content and catalyst calcination temperature. Glycerol conversion and acrolein selectivity depend on the surface acid strength. Catalyst deactivation by coking is also observed, but simple oxidative treatment in air restores the activity of the catalysts completely.

Embedding platinum nanoparticles in a polymer matrix produces a system that reacts like a homogeneous catalyst, but provides the stability and separation advantages of a heterogeneous one.

In silico catalyst optimization is the ultimate application of computers in catalysis. This article provides an overview of the basic concepts of predictive modeling and describes how this technique can be used in catalyst and reaction design.

We present a straightforward protocol for making (phosphanyl- carbene)PdII complexes. These complexes have bidentate ligands containing an acyclic diamino- or aminooxycarbene and a phosphane. The synthesis gives good yields (typically 70–90%) for a variety of complexes (22 compounds). Moreover, it does not require the synthesis of imidazolium salts nor the a priori generation of free carbenes. Three of the new complexes were tested as catalysts for Sonogashira and Hay coupling reactions, with good yields and selectivities.