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Supported coinage-metal catalysts were prepared by strong electrostatic adsorption and used to assess the performance of silver and copper in the oxidative dehydrogenation of methanol to formaldehyde.

Oxygenate fuels are a promising solution to urban air pollution, reducing soot emissions by big margins. Formaldehyde is a major building block for the synthesis of oxygen-rich fuels. Herein we report the synthesis, characterisation and testing of ruthenium on alumina catalysts for the methanol-mediated CO hydrogenation towards oxygenates with the formaldehyde oxidation state. We varied the synthesis parameters and could see interesting correlation between synthesis parameters, final metal loading, crystallite sizes and catalyst activity. The catalysts were tested in a high-pressure three-folded reactor plant in the CO hydrogenation in methanolic media. Interesting relationships between catalyst synthesis, structure and activity could be gained from these experiments.

Das Institut fur Heise Chemie IHCh wurde 1959 gegrundet, um die Entwicklung der Technologie zur Wiederaufarbeitung von Kernbrennstoffen zu unterstutzen. Aufbauend auf dem sog. PUREX-Prozess wurden mogliche Varianten zur Abtrennung von noch nutzbarem Spaltmaterial durch Kombination verschiedenster Extraktions- und Redoxverfahren vom Labor- bis zum Pilotmasstab entwickelt, bis dieser mit nur noch einem Extraktionszyklus auskam. Mit dem Ende der nuklearen Reaktorforschung wurden als Institut fur Technische Chemie neue Themen aus der Umwelt- und Energieforschung aufgegriffen. In dieser Zeit wurde im Rahmen der internationalen Kollaboration GALLEX ein radiochemischer Sonnenneutrino-Detektor gebaut und erfolgreich betrieben.

Die Methodik EDUAR&D, kurz für Energiedaten und -analyse R&D, wird zur Bewertung von Energieeffizienztechniken genutzt. Es handelt sich um einen strukturierten Such- und Analyseprozess, der verschiedene methodische Ansätze zur Darstellung, Analyse und Bewertung der Techniken miteinander verbindet. Ziel ist es, Handlungsempfehlungen, z. B. bzgl. thematischer Schwerpunktsetzung, für die zukünftige Energieforschung im Rahmen der Forschungsförderung und für die Energiepolitik abzuleiten. Die Methodik wird hier am Beispiel der organophilen Nanofiltration und der Latentwärmespeicher vorgestellt.

Correction for ‘Surface reaction kinetics of the methanol synthesis and the water gas shift reaction on Cu/ZnO/Al2O3’ by Bruno Lacerda de Oliveira Campos et al., React. Chem. Eng., 2021, 6, 868–887; DOI: 10.1039/D1RE00040C

In the field of alternative diesel fuels, so-called oxymethylene ethers (OMEs) are currently intensely investigated. Particularly OMEs of the type CH3O(CH2O)nCH3 with n = 3–5 exhibit promising fuel properties and combustion characteristics with strongly reduced particle and NOx emissions. According to their molecular structure, OMEs can be produced from methanol thus enabling sustainable production strategies from CO2 and renewable resources. Compared to the methyl derivatives, analogous compounds with higher alkyl groups (oxymethylene dialkyl ethers, OMDAEs) have been investigated to a much lesser extent. Thus, commercially available OMDAEs, i.e. compounds of the type ROCH2OR bearing ethyl, propyl, butyl and 2-ethylhexyl groups, have been studied. Furthermore, asymmetric compounds of the type R1OCH2OR2 have been synthesized from the symmetric compounds employing transacetalization reactions catalyzed by zeolite BEA-25. The OMDAEs have been characterized by spectroscopic and spectrometric methods and several physico-chemical, thermodynamic and fuel-related data have been determined and compared. Despite their structural peculiarities, such as the oxygen-containing acetal moiety in the molecular backbone, all OMDAEs exhibit properties similar to conventional diesel fuels. Based on experimental and analytical data, the development of tools for the prediction of properties by a simple regression method is described. Furthermore, the suitability of group contribution modelling is investigated for OMDAE compounds.

A three-site mean-field extended microkinetic model was developed based on ab initio DFT calculations from the literature, in order to simulate the conversion of syngas (H2/CO/CO2) to methanol on Cu (211) and Cu/Zn (211). The reaction network consists of 25 reversible reactions, including CO and CO2 hydrogenation to methanol and the water-gas shift reaction. Catalyst structural changes are also considered in the model. Experiments were performed in a plug flow reactor on Cu/ZnO/Al2O3 at various gas hourly space velocities (24–40 L h−1 gcat−1), temperatures (210–260 °C), pressures (40–60 bar), hydrogen feed concentrations (35–60% v/v), CO feed concentrations (3–30% v/v), and CO2 feed concentrations (0–20% v/v). These experiments, together with experimental data from the literature, were used for a broad validation of the model (a total of 690 points), which adequately reproduced the measurements. A degree of rate control analysis showed that the hydrogenation of formic acid is the major rate controlling step, and formate is the most sensitive surface species. The developed model contributes to the understanding of the reaction kinetics, and should be applicable for industrial processes (e.g. scale-up and optimization).

Heterogeneous catalysis and anaerobic syngas fermentation represent two different approaches for the conversion of synthesis gas into chemicals and fuels. This review provides a unique comparison of different reaction paths for the fixation of CO$_{2}$, CO and H$_{2}$ into elementary building blocks such as methanol, acetic acid and ethanol. Operating conditions, reactor engineering, influence of gas impurities, yields, conversion efficiencies as well as downstream product recovery are compared. It was found that mass-specific productivity ranges in the same order of magnitude for both technologies, while space-time yield of heterogeneous catalysis is up to three orders of magnitude higher.

Kinetic investigations and model-based optimization of CuO/ZnO/ZrO2 : H-FER 20 catalytic systems for direct DME synthesis from CO2-rich syngas.

PtX technologies are one major building block of the future energy system based on renewables sources. Dimethyl ether (DME) is an important PtX product that can be used as intermediate the production of CO$_{2}$-neutral base chemicals. New applications lead to an increase of the global production and the optimization of the process efficiency, especially when considering decentralized synthesis. This review article puts some spotlights on recent developments in methanol and the direct DME synthesis with a special focus on the modeling and bifunctional catalyst. This study is expected to provide a foundation for future works in the field of catalysis research based on catalysts design and kinetic modeling.

Reaction kinetic modeling, model-based optimization and experimental validation are performed for the direct synthesis of dimethyl ether from CO2 rich synthesis gas. Among these disciplines, experimental methods and models are aligned in a stringent way of action, i.e., the same setup and models are applied throughout the whole contribution. First, a lumped reaction kinetic model from the literature is modified and parametrized to fit a vast array of 240 data points measured in a laboratory fixed bed reactor. The data were acquired using a mechanical mixture of the commercial catalysts CuO/ZnO/Al2O3 and γ-Al2O3. For this setup, a predictive model is derived and applied within dynamic model-based optimization. Here, the single-pass COx conversion serves as objective function while the operating conditions and composition of the mixed catalyst bed are the optimization variables. Finally, the optimization results obtained numerically are validated experimentally verifying the identified performance enhancement qualitatively. The remaining quantitative deviations yield valuable insights into model and methodological weaknesses or inaccuracies, closing the loop between kinetic investigations, model-based optimization and experimental validation.

Neue regenerativ hergestellte Kraftstoffe, sogenannte reFuels, konnen schon kurzfristig zur CO2-Reduktion der Bestandsflotte beitragen. Das Karlsruher Institut fur Technologie (KIT) zeigt, welche Bausteine bei der Entwicklung CO2-neutraler Mobilitat zusammenwirken mussen. Wesentlicher Faktor bei der Einfuhrung von reFuels ist der hohe Zeitvorlauf bei der Projektierung und beim Bau der Produktionsanlagen. Zudem ist zeitnah eine gesetzlich verankerte Planungssicherheit und Anerkennung dieser neuen Kraftstoffe unabdingbar.

Oligomeric oxymethylene dimethyl ethers (DMEs; OMDMEn) are acetals of the type CH3O(CH2O)nCH3 with a high oxygen content and without carbon–carbon bonds in the molecular structure. Therefore, formation of soot and NOx emissions is largely suppressed during combustion. Oligomers with n = 3–5 exhibit properties similar to conventional diesel fuel and this stimulated extensive research in this field. Reactions of OMDME1, the corresponding ethyl derivative OMDEE1 and dimethyl ether (DME) with trioxane have been carried out employing zeolite BEA25 as acidic catalyst. Thus, oligomer mixtures with n = 1–5 are obtained and very small amounts of higher oligomers are also formed. OMDMEn- or OMDEEn-forming reactions from the starting materials take place as well as subsequent transacetalization reactions which lead usually to a product distribution according to a Schulz–Flory distribution. Several transacetalization reactions have been studied, e.g. reactions of OMDME1 with OMDME3 and OMDEE1 with OMDEE3, which lead to the typical mixtures with n = 1–5. Reactions of OMDME1 with OMDEE1 yielded ethoxymethoxymethane, i.e. the acetal with mixed end groups. This allows for the tuning of oligomer mixtures and adjustment of properties according to the required demands of the respective application. Regarding DME as starting compound, the transacetalization reaction with OMDME3 yielded only small amounts of OMDME1–5 while the reaction of DME with trioxane yielded considerable amounts of the oligomers. The reaction is comparatively slow enabling a kinetic control of the oligomer distribution which exhibits an elevated selectivity for the desired OMDME3–5 fraction in the beginning of the reaction.

The environmental impact of the increasing anthropogenic CO2 emissions and the depletion of essential resources, once subjects of concern only for a minority of specialists, are now in the focus of many institutions and are de facto top priorities in many agendas. The ensuing environmental regulations, improved safety requirements, and growing critical public view on the chemical industry are the main reasons for an intense search for alternative synthetic routes to commodity chemicals and specialty chemicals. The skillful utilization of waste biomass, an inexhaustible resource, is revealed to be an important tool for a balanced CO2 management and the way to promising feedstock for many chemical and biochemical syntheses. The scope of the present contribution is to outline the main differences between chemical and biotechnological synthesis routes starting from waste biomass, focusing on C4-chemicals as an exemplary case study.

Industrial Kraft Lignin (KL) prepared by LignoBoost® technology was treated via hydrothermal base catalysed depolymerisation (HBCD). KL was dried and divided into methanol soluble and insoluble fractions. The insoluble fraction was treated in 1 M NaOH (aq) at 300 °C. After precipitation with HCl (aq), the solids yield was ca. 60 wt%. These solids demonstrated improved thermal stability and carbon content, increased solubility in MeOH and reduction in polydispersity. With a view to the use of the product in the preparation of carbon-based materials (e.g. carbon fibres (CF)), thermal analysis was undertaken, revealing a lack of a glass transition below the decomposition temperature, excluding melt pinning. However, a high solubility in organic solvents renders the product a suitable candidate for solvent spinning and for the production of renewable low-cost CFs. Additionally, the process generated an oily liquid phase with yields of ca. 10 wt% containing valuable catechol and methylated derivatives., RJW acknowledges financial support of the Fraunhofer Society and Fraunhofer Institute for Solar Energy Systems ISE through an “ATTRACT” award. PSS gratefully acknowledges the Spanish Ministry for Economy and Enterprise (MINECO) for a Ramón y Cajal fellowship (RYC-2014-16759) and a proyecto de I+D+I para jóvenes investigadores (MAT2014-59674-JIN). RJW and MO would also like to acknowledge the support of the joint Max Planck Society/Fraunhofer Society project “Dendrorefining”. Dr. H. Scherer (AK Krossing; University of Freiburg, Germany) is especially thanked for his assistance with NMR measurements. The authors would like to thank the ICTP-CSIC characterisation service for their help in measuring the DSCs of the samples. The Fraunhofer IAP (Potsdam, Germany) is thanked for assistance with GPC measurements.

The one-step synthesis of dimethyl ether over mechanical mixtures of Cu/ZnO/Al

Dimethyl ether (DME) is a power-to-liquids product with interesting key characteristics and a broad spectrum of applications as a green fuel, as a compound for the chemical industry and as a chemical building block. At present, DME is produced from fossil resources like natural gas and coal. The shift to renewable production from CO2 and hydrogen will allow emerging pathways for the production of DME to find its way to the market. State-of-the-art and emerging DME production pathways are presented in detail. Particular focus is hereby put on the influence of a renewable production based on CO2 and hydrogen. Last but not least, economic insights into a power-to-DME process are given in the last chapter.

Catalyst systems for the conversion of synthesis gas, which are tolerant to fluctuating CO/CO

Hierarchical H-ZSM-5 zeolites are a promising class of heterogeneous catalysts that have shown encouraging results in lab-scale studies for the production of gasoline from dimethyl ether (DTG conversion). However, the influences of mesopore formation and shaping on various catalyst properties are still under debate. In this study, a series of H-ZSM-5 zeolites with hierarchical pore structures were prepared by modifying commercially available zeolites via alkaline treatment ("desilication"). The powdered zeolites were shaped into technical catalyst bodies by wet extrusion using either silica or alumina binders. All materials were extensively characterized. The different interactions during alkaline treatment were related to the observed modifications in the zeolite properties of the materials obtained. Although many properties of modified and untreated zeolite powders remained predominantly unchanged in their shaped catalyst equivalents, both binders affected certain material characteristics, particularly those related to their acidity. Finally, preliminary tests showed enhanced catalytic performance of hierarchical ZSM-5 catalysts in DTG conversion.

Well-defined Pd/Ga-nanoparticles were prepared and used as a precursor for the methanol active component in a bifunctional syngas-to-dimethyl ether catalyst. In situ X-ray absorption spectroscopy experiments were employed both to unravel the initial formation of the active catalyst phase in reductive H 2 atmosphere and to further monitor changes of the nanoparticles under conditions of dimethyl ether synthesis at a pressure up to 20 bar (250 °C). The catalytic studies were conducted using simulated biomass-derived, CO-rich syngas in a continuous-flow reactor, with the bifunctional catalyst offering the two types of active sites, i.e. for methanol synthesis (Pd/Ga nanoparticles) and its subsequent dehydration (γ-Al 2 O 3 ), in close proximity. As compared to the conventional Cu/Zn-based reference catalyst prepared via a similar procedure, the Pd/Ga-based catalyst showed a promising activity together with a notable stability with time on stream and a high temperature tolerance (up to 300 °C). A kinetic model which considers the individual reactions involved in direct DME synthesis based on power law equations was used to fit the experimental data, and the apparent activation energies were compared to the Cu/Zn-based catalyst.

Hybrid catalysts were prepared using well-defined, colloidal Cu/Zn-based nanoparticles as building units. The nanoparticles were immobilized on acidic supports (i.e., γ-Al2O3, HZSM-5, and HY) to yield a series of bifunctional catalysts with a close proximity of active sites for both methanol synthesis and its further conversion to dimethyl ether (DME) or hydrocarbons (HCs). By this model kit principle, a high comparability of the bifunctional catalysts was ensured. The catalysts were characterized in depth regarding their structure and catalytic performance in the conversion of CO-rich synthesis gas. In situ XAS studies demonstrated the formation of the active phase under reducing conditions. The present study revealed important material parameters to control activity and selectivity of the bifunctional catalysts either towards DME or liquefied petroleum gas (LPG) products in the direct conversion of simulated biomass-derived synthesis gas. In particular, Cu loading, pore structure and Si:Al ratio were investigated.

Oligomeric oxymethylene ethers (OMEs) are promising fuels for internal combustion engines with self-ignition. A tremendous reduction of soot, nitrogen oxide and hydrocarbon emissions can be realized by employing OMEs. This work describes the synthesis of OMEs from dimethyl ether (DME) and trioxane. Zeolite H-BEA 25 was found to be a suitable catalyst for this reaction and a study on reaction parameters (e.g. temperature, reactant feed ratio and reaction time) has been carried out. A maximum DME conversion of 13.9 wt% could be obtained and the maximum reactant-related product yield for OME3–5 was 8.2 wt%. An OME formation mechanism is proposed which explains the observed product spectrum.

Oligomeric oxymethylene dimethyl ethers (OMEs) of the type CH3O-(CH2O)n-CH3 are promising diesel fuels with an enormous potential for the reduction of soot and NOx emissions. Oligomers with n = 3–5 are particularly advantageous, since their physicochemical and combustion properties are similar to conventional diesel. OMEs can be produced from methanol and formaldehyde but a series of byproducts, especially hemiformals, glycols, water and minor amounts of cyclic ethers, are also formed. These need to be separated from the product mixtures, which affects efficiency of this synthesis pathway. To isolate the desired OMEs, a one-step synthesis/extraction procedure is described. It implies highly selective extraction of OMEs from aqueous reaction solutions employing hydrocarbons as extraction agents. If fuel-type hydrocarbons are used, the resulting OME-hydrocarbon blends can be directly used in fuel applications. The corresponding oxymethylene diethyl ethers (OMDEEs) have also been investigated. Compared to OMEs, OMDEEs exhibit an increased solubility in nonpolar media but, as a result, solubility of educts and byproducts also increases. OME blends with hydrogenated vegetable oil and diesel have been prepared containing 10% of OMEs. It could be shown that such blends meet current diesel standards to a large extent.

The life cycle energy consumption and greenhouse gas (GHG) emission performances of forest biomass-derived oxymethylene ether (OME) synthesis used as a diesel additive are analyzed in this study. OME, a new alternative liquid fuel, has great miscibility with conventional fuels like diesel. OME can reduce combustion emissions significantly when used as a diesel additive without any modification to the engine. A data-intensive spreadsheet-based life cycle assessment (LCA) model was developed for OME synthesis from woodchips derived from two different kinds of forest biomass, whole tree and forest residue. Woodchip harvesting, chip transportation, chemical synthesis of OME from biomass-derived syngas, OME transportation to blending, and vehicle combustion of this transportation fuel were considered in the system boundary. The results show that the whole tree pathway produces 27 g CO2eq/MJ of OME, whereas the forest residue pathway produces 18 g CO2eq/MJ of OME over 20 years of plant life. The difference is mainly due to some emissions-intensive operations involved in biomass harvesting and biomass transportation such as skidding, road construction, etc., in the whole tree pathway. Also, vehicle combustion was found to be the most GHG-intensive unit for both pathways. OME combustion in a vehicle accounts for about 77% and 83% of the total life cycle GHG emissions for the whole tree and forest residue pathways, respectively. This study also compares the diesel life cycle emission numbers with the life cycle emissions of OME derived from forest biomass, and it was observed that GHG emissions can be reduced by 20–21% and soot (black carbon) emissions can be reduced by 30% using a 10% OME blended diesel as a transportation fuel compared with conventional diesel.

Oligomeric oxymethylene dimethyl ethers (OME n , CH 3 O(CH 2 O) n CH 3 ) bearing three to five CH 2 O units are promising diesel fuels for the reduction of soot and NO x emissions. Regarding the production of OMEs, a highly optimized process has not been realized yet. This work describes efficient synthesis of OMEs from dimethoxymethane (DMM) and trioxane in batch experiments at room temperature and atmospheric pressure. To ensure high reactivity and high OME yields, dry educts have been used and the influence of water has been investigated in detail. The ion exchange resin Amberlyst36 and zeolites have been employed as acidic catalysts. Zeolite BEA25 exhibited highest catalytic activity and the reaction could be completed within 12 min at 25 °C. Furthermore, the formation of byproducts could be fully eliminated.

A catalyst screening comprising zeolites and ion exchange resins for the synthesis of oligomeric oxymethylene dimethyl ethers (OME) from methanol (MeOH) and formaldehyde (FA) has been carried out. All catalysts led to the same product spectrum and parameters for chemical equilibrium have been determined. The ion exchange resin Dowex50Wx2 showed highest activity and reaction kinetics has been investigated employing this catalyst. The influence of the FA:MeOH ratio and water as well as refeeding of OMEs with undesired chain lengths have been considered in the kinetic model, which is based on a hyperbolic approach. Experiments have been carried out in the temperature range between 40 and 120 °C and variable FA:MeOH ratios from 0.5 to 1.5 g/g have been employed. Regarding water, up to 23 wt.% have been added to the reaction mixtures to investigate its influence on yield and reaction rate. Low water contents lead to high OME selectivities. By varying the FA:MeOH ratio, chain lengths of the OMEs can be influenced. Regarding the most active catalyst Dowex50Wx2, 90% of equilibrium conversion is reached after 5 min at 60 °C employing a catalyst loading of 1 wt.%. A study on the long term performance of the catalyst has been carried out and after 17 days the decrease of activity was below 10% while selectivity remained the same. For different Dowex catalysts a general kinetic model could be developed, which is not limited to Dowex50Wx2.