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A new series of electrocatalysts consisting of Ag nanoparticles supported on graphitic carbon nitride (g-C3N4) are presented. The combination of nanostructured silver and a carbon nitride support results in the direct generation of synthesis gas (CO+H2) during the electrocatalytic reduction of CO2 in water. By using a state-of-the-art electrocatalytic setup, the influence of different operation parameters over the final product composition is shown. The H2/CO product ratio can easily be tuned from 100:1 to 2:1 with high reproducibility by controlling the applied potential and the Ag loading. More importantly, long-term and catalyst reuse experiments demonstrate the robustness of these electrodes, which could be operated for over 20 h time on stream and reused several times without any evident loss of activity or selectivity. Our results highlight the potential of nanostructuring Ag-based catalysts and the relevance of the selected support for the green valorization of CO2.

Nitrogenoxides (NOx, including NO and NOx) are a group of hazardous, toxic and harmfulgasses, which have an adverse effect on both environment and human health,e.g., acid rain, photochemical smog, and affecting the human respiratorysystem. The NOx concentration in most of the EUcities exceeds the EU annual limit value (40 μg/m3). Around40% of the emitted NOx is attributedto transport related emissions. In currently applicable Euro 6, the real NOx emissionfrom a diesel car is on average 400% than the Euro 6 regulation limit allows ifmeasured under more realistic driving conditions. Although NSR and SCR DeNOx systemshave been broadly investigated and commercially applied with the aim to reduceNOx emissions from lean burn engines,some common problems still exist, e.g., a narrow temperature window and a lowgas hourly space velocity (up to 50.000 L/L/h)in order to convert the NOx selectivelyinto Nx. Due to the in practice high NOxemissionfrom September 2017 additional legislation will be in force to arrive at a morerealistic determination of the highly dynamic NOxemissionby among others the introduction of the real driving emission (RDE) test in thecertification procedure. The Di-Air (Diesel NOxaftertreatment by Adsorbed Intermediate Reductants) system was developed by Toyota(2011-2012) and is still under development. This Di-Air system showed promiseby yielding a high NOx conversion,especially at high temperature (up to 600 ∘C) and high gas hourly space velocity (up to 125.000 L/L/h).This system opts to meet the future stringent NOxreductionrequirements under RDE test conditions (Chapter 1)…

A heterogeneous molecular catalyst based on Ir(III) Cp* (Cp*=pentamethylcyclopentadienyl) attached to a covalent triazine framework (CTF) is reported. It catalyses the production of hydrogen from formic acid with initial turnover frequencies (TOFs) up to 27,000 h(-1) and turnover numbers (TONs) of more than one million in continuous operation. The CTF support, with a Brunauer-Emmett-Teller (BET) surface area of 1800 m(2) g(-1), was constructed from an optimal 2:1 ratio of biphenyl and pyridine carbonitrile building blocks. Biphenyl building blocks induce mesoporosity and, therefore, facilitate diffusion of reactants and products whereas free pyridinic sites activate formic acid towards β-hydride elimination at the metal, rendering unprecedented rates in hydrogen production. The catalyst is air stable, produces CO-free hydrogen, and is fully recyclable. Hydrogen production rates of more than 60 mol L(-1) h(-1) were obtained at high catalyst loadings of 16 wt % Ir, making it attractive towards process intensification.

The synthesis of single-atom catalysts and the control of the electronic properties of catalytic sites to arrive at superior catalysts is a major challenge in heterogeneous catalysis. A stable supported single-atom silver catalyst with a controllable electronic state was obtained by anti-Ostwald ripening. An electronic perturbation of the catalytic sites that is induced by a subtle change in the structure of the support has a strong influence on the intrinsic reactivity. The higher depletion of the 4d electronic state of the silver atoms causes stronger electronic metal-support interactions, which leads to easier reducibility and higher catalytic activity. These results may improve our understanding of the nature of electronic metal-support interactions and lead to structure-activity correlations.

The isomerization of (1-13C)-D-glucose to an equilibrium mixture of (1-13C)-D-glucose and (1-13C)-D-fructose by the enzyme glucose isomerase (E.C. 5.3.1.5) has been followed using 13C NMR spectroscopy. It is concluded that the α-D-glucopyranose and the α-D-fructofuranose form are the reactive species for the enzyme.

The rapidly increasing use of finite fossil fuel resources and growing environmental concerns have compelled many countries to explore alternatives, especially renewable energy sources, to ensure a sustainable future energy and transportation fuel supply and demand. Of the many available sources, the conversion of biomass into valuable liquid transportation fuels is an attractive option. Indeed, many conversion routes for biofuel production have been explored: (1) bioalcohols (e.g. , ethanol, butanediol) from fermentation of sugars obtained from cornstarch biomass; (2) transesterification of plant-based oils or animal fats to biodiesel ; (3) hydrotreatment of vegetable oils to green diesel ; (4) pyrolysis of biomass to bio-oil, and its upgrading; (5) gasification of biomass via Fischer–Tropsch synthesis via syngas; and (6) catalytic cracking of vegetable oils to gasoline, diesel, and light olefins similar to the standard fluid catalytic cracking (FCC) process [525 8C, atmospheric pressure, catalyst-to-oil (CTO) ratio 6–12 gg , and residence time between 2–5 s]. Depending on the feedstock type, some of the above-mentioned processes are already commercially available, but except for the FCC of vegetable oils only the fermentation process is directly designed for gasoline production. In addition, some of the processes above are still under development because they are very energyand capital-intensive. Thus, catalytic cracking of biomass (e.g. , vegetable oils) is the only process that is able to directly produce gasoline, along with diesel and light olefins components. Furthermore, the compatibility of vegetable oil processing with the existing infrastructure of the standard FCC process makes this process much more economically feasible than other methods. Most of the available studies on catalytic cracking of vegetable oils (triglycerides) have been carried out in a fixed-bed microactivity (MAT) reactor, which has different hydrodynamics and much longer contact times (20–75 s) compared to a commercial riser reactor (2–5 s). Only a few studies on vegetable oil cracking in entrained flow-type riser reactors have been carried out. Under typical FCC conditions, Dupain et al. studied both the thermal and catalytic cracking of a rapeseed oil in an isothermal plug-flow microriser reactor, which mimics the actual riser unit very well. Despite the differences between fixed-bed and riser reactors, the catalytic cracking of vegetable oils resulted in very large amounts of aromatics, both in the gasoline and diesel product slates, owing to oxygen removal from the triglycerides, mainly as water and, to a minor extent, to carbon oxides (COx). [12] The formation of water means that the hydrogen that reacts with oxygen comes from the vegetable oil molecules. In this manner the molecules will have a higher degree of unsaturation, enhancing the formation of thermodynamically favorable aromatics under FCC operating conditions (>525 8C and atmospheric pressures). Furthermore, lower gasoline yields and higher yields to light cycle oil (LCO; a diesel blending component) were obtained from unsaturated vegetable oils compared to conventional petroleum feedstocks. The concerns above clearly emphasize that there is a pressing need to improve the catalytic cracking process for vegetable oils to enhance gasoline production and reduce the aromatic content of the liquid fuel product. In the present study, we develop a new concept by designing an efficient cracking system to greatly increase gasoline production from unsaturated vegetable oils. To achieve this, our strategy considers two options: incorporation of metal functionality onto the base FCC catalyst, and co-feeding H2 into the reaction system. The main rationale behind this idea is that co-feeding H2 may assist in saturating the double bonds present in the system and/or remove oxygen as water. However, H2 alone is not expected to fully serve the purpose under realistic FCC conditions (near atmospheric pressure). Therefore, we have considered metal incorporation on base FCC catalyst for efficient exploitation of H2 in the water formation. The metals could, however, also have an adverse effect over hydrogenation–dehydrogenation activity, leading to even more aromatization. A commercial FCC equilibrium catalyst (Ecat) and Ecat catalysts with deposited metal (nickel and platinum Ecat) were considered. The surface areas of all the catalysts were ca. 160 mg. 1 X-ray diffraction (XRD) data showed only peaks related to the base Ecat for all samples, which suggests that the textural properties of the base Ecat were not modified by the metal incorporation. Furthermore, scanning electron microscopy (SEM/EDX) analysis revealed that the distribution and location of the metal in the Ecat appeared to depend on the metal used: Ni was found only inside the catalyst, whereas Pt was present on both the external surface and inside the catalyst. Typically, catalytic cracking of triglycerides (e.g. , rapeseed oil) is always initiated by thermal decomposition of triglycerides into fatty acids via radical cracking reactions. After this initial step, the acid zeolite catalyst controls the process and converts the formed fatty acids into a wide range of products, such as gasoline, LCO, light gaseous hydrocarbons, and some [a] Dr. T. V. M. Rao , Prof. M. Makkee Catalysis Engineering, ChemE Delft University of Technology Julianalaan 136, 2628 BL Delft (The Netherlands) Fax: (+31)15-278 5006 E-mail : m.makkee@tudelft.nl [b] M. M. Clavero Department of Chemical and Environmental Technology ESCET, Universidad Rey Juan Carlos C/Tulipan s/n, 28933 Mostoles, Madrid (Spain)

Liquid holdup and dispersion are reported for a column of 2 mm internal diameter, filled with 0.1 mm spherical particles, for multiphase flows with hydrocarbon liquid flow rates of 10–100 μL/min and nitrogen gas flow rates of 50–1000 μL/min using different tracers with varying diffusion coefficients and vapor pressures. It was found that the liquid holdup (liquid volume/external void volume) was between 0.65 and 0.85, with variations between different experiments and limited impact of flow rate on the holdup. The dispersion characteristics were very similar to single-phase dispersion. The particle Peclet number for dispersion was close to 0.2. This value was of the same order of magnitude – just a factor of two to three lower – as the value that was obtained without gas flow. Tracer volatility did cause the tracer to elude earlier, but did not cause significant additional dispersion. The results suggest that the fluid mechanical interaction between the gas and the liquid was very limited.

Hybrid carbon-alumina supports, synthesised by pyrolysis of grafted 4,4'-methylenebis-(phenylisocyanate) moiety on the alumina surface, were characterised by X-ray photoelectron spectroscopy. The recorded Al 2p and C 1s envelopes showed asymmetry that decreased with an increase in carbon loading. In all experimental Al 2p envelopes, the high-energy individual components at 75.3-75.9 eV were present along with the low-energy component at 74.0 eV typical for Al 2 O 3 . In the case of the C Is envelope, the component around 284.3-284.4 eV and three high-energy individual components at 285.9-286.0, 288.0-288.3 and 290.1-290.6 eV were observed. The presence of the high-energy Al 2p components can be explained considering the occurrence of a steady-state charging of the different parts of insulating alumina supports. The component around 284.3-284.4 eV in C Is envelopes can be attributed to carbon, which constitutes the coating and, hence, ensures surface conductivity. The component around 285.9-286.0 eV is connected with carbon in carbonaceous surface species, which do not form the conducting layer on the alumina support. Carbonaceous surface species associated with C-O, C=O and O=C-O groups in carbon coating can be also identified due to the presence of corresponding components in XPS spectra at 285.9-286.0, 288.0-288.3 and 290.1-290.6 eV.

The water-gas shift selectivity and stability of a Rh/Fe2O3/ZrO2 catalyst under typical industrial conditions is improved by the presence of small amounts of sulfur (

A novel concept is presented for the immobilization of a homogeneous catalyst. A hydroformylation catalyst was covalently anchored to monoliths that were constructed as the blades of a mechanical stirrer and used in a batch process. The catalyst was effective in the hydroformylation of both higher and lower alkenes and showed a high regioselectivity for the linear aldehyde. The concept was proven to be useful in a liquid organic and aqueous phase as well as in the gas phase and the catalyst could be used numerous times without catalyst deterioration. No catalyst deactivation was observed in a period over half a year.

The influence of process parameters such as temperature (400-560K), H2/CCl2F2 ratio (2.2-20), and Weight Hourly Space Velocity (WHSV) (0.3-1.0 g/(g · h)) on the hydrogenolysis of CCl2F2 into CH2F2 over palladium on activated carbon has been investigated. The reactivity of CHCIF2 and CH2F2 and the influence of HCl were also examined. In the reaction of CCl2F2, the main product is CH2F2. Significant amounts of CHCIF2 and CH4 are also found. The catalyst shows a remarkably high selectivity to CH2F2, in the range of 70-90 mol%, at all conversion levels in a broad range of process conditions. A mechanism is proposed in which the reaction proceeds mainly via parallel reaction pathways. One route results in CH2F2 and CHCIF2, while the other route yields CH4. The selectivity to CH2F2 and CHCIF2 is determined by the amount of adsorbed chlorine on the catalytic surface and a constant selectivity for CH4 was found. High selectivity for CH2F2 can be achieved at high H2/CCl2F2 ratios and low HCl concentration. The postulated mechanism is supported by thermodynamic data.

The front cover artwork for Issue 13/2016 is provided by researchers from the Catalysis Engineering group, Chemical Engineering Department, Delft University of Technology (The Netherlands). The image shows the formation of covalent triazine framework (CTF) based spheres by using commercially available polyimide as a binder. See the Full Paper itself at http://dx.doi.org/10.1002/cctc.201600419.

The pH effect on the Pd-catalyzed oxidation of glucose to gluconic acid was studied. The oxidation reactions were performed in the pH range 2 to 9 in a batch reactor using Pd/C or Pd black as the catalysts and monitoring the behaviour of the catalyst during the oxidation reaction. The Pd-glucose system was also studied by cyclic voltammetry. It is concluded that gluconic acid in its free form reversibly inhibits the oxidation process in acidic media.

Several non-supported oxidic compounds potentially present in a Cu/K/Mo/Cl catalyst (copper molybdates, potassium molybdates, and a mixed copper-potassium molybdate (K2Cu2(MoO4)3)) have been tested individually on their activity in the oxidation of a model soot (Printex-U, which non-catalytically oxidizes at 875 K). These oxidic compounds are active between 665 and 720 K, but only after establishment of ‘tight contact’ between the catalyst and soot in a ball mill. Without the ball mill procedure (‘loose contact’) these oxides are less active (the soot oxidation temperature is shifted to about 790 K), while a ZrO2 supported Cu/K/Mo/Cl catalyst still shows a high activity around 670 K. Hence, the ‘loose contact’ activity of the supported Cu/K/Mo/Cl catalyst is not explained by the presence of an active oxidic compound. DRIFT and XRD analyses have shown that addition of KCl to CuMoO4 (two compounds present within the Cu/K/Mo/Cl catalysts) followed by calcination at 950 K in air, eventually results in the formation of a mixed potassium-copper molybdate. Simultaneously several volatile copper, potassium and chlorine containing compounds (e.g. K2CuCl4) are formed. These copper and chlorine containing compounds possess a high ‘loose contact’ soot oxidation activity between 600 and 690 K. A catalytic cycle, involving Cu2OCl2, is proposed to explain the high ‘loose contact’ activity of copper chlorides and supported Cu/K/Mo/Cl catalysts. The activity of the latter catalyst will be maintained as long as Cu2OCl2 can be reformed by reaction of copper molybdates with KCl, which serves as a chlorine supplier.

A combination of 11B and 13C NMR spectroscopy with several model compounds has been used to elucidate the nature of the ester formation between borate and D-mannitol, D-glucitol, D-fructose and D-glucose in aqueous solution at pH 6-12 and at 25 °C. At high carbohydrate/borate ratios, D-mannitol shows the selective formation of bis(D-mannitol) 3,4:3′4′ -borate, whereas D-glucitol forms a mixture of six different bis(D-glucitol) borate esters involving both 2,3- and 3,4-dihydroxyl moieties. Bis(D-fructose) and bis(D-glucose) borate esters consist of pairs of diastereomers of the 2,3-β-and 1,2-α-furanose moieties, respectively. At low carbohydrate/borate ratios, mono-, di- and, sometimes, tri-borate esters are formed, e.g. mixture of α-D-glucofuranose 1,2:3,5-diborate and α-D-glucofuranose 1,2:5,6-diborate for D-glucose and a mixture of β-D-fructopyranose 1,2:4,5-diborate and β-D-fructopyranose 2,3:4,5-diborate for D-fructose. The overall stability constant for the borate di-esters of D-mannitol, D-glucitol and D-fructose is about two orders of magnitude higher than that of D-glucose.

The present commercial production of D-mannitol, a valuable nutritive sweetener, takes place by hydrogenation of 1:1 D-glucose/D-fructose mixtures over nickel. The low D-mannitol yield (25 — 30%), however, asks for the development of alternative procedures. A literature survey of the various production methods is given, including some other possible combinations of known procedures. It is concluded that the simultaneous use of glucose isomerase and copper-on-silica (combi-process) is a promising procedure for the preparation of D-mannitol from D-glucose or D-glucose/D-fructose syrups.

A survey is given of glucose isomerase, its sources, its mechanism of isomerization and its data and properties in three different immobilized forms. In addition, the effect of a number of parameters on the activity of immobilized glucose isomerase has been investigated, e. g. hydrogen pressure, Mg(II) and Ca(II), transition metal ions, borate and sugar alcohols. Immobilized glucose isomerase remains sufficiently active under hydrogenation conditions to maintain D-glucose and D-fructose in equilibrium. D-Glucitol, in contrast to D-mannitol, has some inhibiting effect on the enzyme action. The D-glucose/D-fructose equilibrium constant is independent of the total sugar concentration (between 0.2 – 2.2-M). Glucoseisomerase und ihr Verhalten unter Hydrierungsbedingungen. Es wird eine Ubersicht uber Glucoseisomerase, ihre Herkunfte, ihren Isomerisierungsmechanismus sowie uber ihre Daten und Eigenschaften in drei verschiedenen immobilisierten Formen gegeben. Daruber hinaus wurde die Wirkung einer Anzahl von Parametern auf die Aktivitat von immobilisierter Glucoseisomerase, Z. B. Wasserstoffdruck, Mg(II) und Ca(II), Ubergangsmetall-Ionen sowie Borat und Zuckeralkohole, untersucht. Immobilisierte Glucoseisomerase behalt unter Hydrierungsbedingungen genugend Aktivitat, um D-Glucose und D-Fructose im Gleichgewicht zu halten. D-Glucitol (D-Sorbitol) hat im Gegensatz zu D-Mannitol einen gewissen inhibierenden Einflus auf die Enzymwirkung. Die D-Glucose/D-Fructose-Gleichgewichtskonstante ist unabhangig von der Gesamtzuckerkonzentration (0,2 — 2,2-M).

The isomerization of (1-13C)-D-glucose to an equilibrium mixture of (1-13C)-D-glucose and (1-13C)-D-fructose by the enzyme glucose isomerase (E.C. 5.3.1.5) has been followed using 13C NMR spectroscopy. It is concluded that the α-D-glucopyranose and the α-D-fructofuranose form are the reactive species for the enzyme.