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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).

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.

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.

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.

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.

Lignocellulosic biomasses are strongly connected composites of cellulose, hemicelluloses, and lignin. A pretreatment is required in order to make these components available for their later conversion into chemicals. At this point, two strategies have to be considered: to either produce chemicals via microorganism or enzymes (1), or by chemical conversion (2). The focus of this article is the second strategy, which is chemical conversion, performed in water to produce the final products furfural and 5-hydroxymethylfurfural (HMF). Reviewed first is the composition of cellulose and hemicelluloses as well as their degradation chemistry in water. Then, fundamental modes of action and process parameters of pretreatment methods in aqueous solution are summarized. The pretreatment methods discussed here are steam explosion, treatment with hot liquid water, diluted and concentrated acids, as well as alkaline solutions. Finally, the advantages and disadvantages of these pretreatments are discussed for lignocellulosic biomass.

Hydrolysis of lignocellulosic biomass is a crucial step for the production of sugars and biobased platform chemicals. Pretreatment experiments in a semi-continuous plant with diluted sulphuric acid as catalyst were carried out to measure the time-dependent formation of sugars (glucose, xylose, mannose), furfurals, and organic acids (acetic, formic, and levulinic acid) at different hydrolysis temperatures (180, 200, 220 &deg, C) of one representative of each basic type of lignocellulose: hardwood, softwood, and grass. The addition of the acid catalyst is followed by a sharp increase in the sugar concentration. Xylose and mannose were mainly formed in the initial stages of the process, while glucose was released slowly. Increasing the reaction temperature had a positive effect on the formation of furfurals and organic acids, especially on hydroxymehtylfurfural (HMF) and levulinic acid, regardless of biomass type. In addition, large amounts of formic acid were released during the hydrolysis of miscanthus grass. Structural changes in the solid residue show a complete hydrolysis of hemicellulose at 180 &deg, C and of cellulose at 200 &deg, C after around 120 min reaction time. The results obtained in this study can be used for the optimisation of the hydrolysis conditions and reactor design to maximise the yields of desired products, which might be sugars or furfurals.

Aktuelle Trends aus der chemischen Prozesstechnik im Rahmen der Begleitforschung des Forschungsnetzwerkes Energie in Industrie und Gewerbe (EE4InG) werden vorgestellt. Wir gehen davon aus, dass die Trends zirkulare Wirtschaft und beschleunigte globalisierte Innovation (Modularisierung, Prozessintensivierung und Digitalisierung) bis 2030 auf die Chemieindustrie wirken. Die Technologieentwicklung anhand dieser Trends erlaubt es dem Chemieingenieurswesen, zukunftig entscheidende Beitrage zur Flexibilisierung und Defossilisierung der Wertschopfungsketten zu leisten.

A methanol catalyst based on Cu/ZnO/Al 2 O 3 (CZA) was prepared and mixed with four different solid acids, a pure γ-Al 2 O 3 , a SiO 2 -doped γ-Al 2 O 3 , an AlPO 4 -doped γ-Al 2 O 3 and the zeolite H-MFI 400, respectively. These admixed catalyst systems were tested in the direct synthesis of dimethyl ether from CO-rich synthesis gas (CO:H 2 = 1), which is typical for biomass-derived synthesis gas. Reactions were carried out in a laboratory plant at 250 °C and 51 bar for 120 h time-on-stream followed by catalyst passivation with O 2 and regeneration by hydrogenation. After catalyst regeneration, the reaction was run again for another 72 h. The catalyst system containing the zeolite exhibited highest CO-conversion. However, all catalysts showed a drop of activity after the passivation- and regeneration-process and the system with the SiO 2 -doped γ-Al 2 O 3 showed the lowest loss of activity. Investigation of the catalysts after reaction by N 2 O-pulse chemisorption and XRD revealed that agglomeration of catalyst species took place leading to an increased Cu 0 -particle size for all systems. This phenomenon was less pronounced in the case of the system containing the SiO 2 -doped γ-Al 2 O 3 . Thus, the main cause of catalyst deactivation was found to be sintering of the catalytically active components.

Oligomeric oxymethylene dimethyl ethers (OMDMEs, CH3O–(CH2O)n–CH3) are promising diesel fuel additives, which can reduce soot formation as well as NOx emissions. Due to the poor availability of high purity OMDMEs a comprehensive characterization of diesel standards was not feasible until now. Two types of oxymethylene dialkylethers (OMDMEs and oxymethylene diethyl ethers, OMDEEs) were synthesized, purified and characterized with respect to their physico-chemical and fuel properties. Density, melting point, flash point, auto ignition point as well as lubricity, kinematic viscosity and surface tension of OMDMEs and OMDEEs were measured and compared to the corresponding n-alkanes. Fuel requirements such as boiling points, flash points and surface tensions can be fulfilled by OMDMEs and OMDEEs. Furthermore, OMDMEs (n = 3–5) and OMDEEs (n = 2–4) are, due to their high cetane numbers of 124–180 and 64–103, particularly promising since cetane numbers in this range can lead to improved motor efficiency and smoother fuel combustion. Additionally, the heat of combustion as well as the standard enthalpy of formation and reaction were determined. Apart from somewhat lower heating values, OMDMEs exhibit fuel properties similar to conventional diesel complying the required fuel standards without the need of changing engines or fuel infrastructures.

Bio-ethanol is a renewable fuel and can be converted to high-values chemicals. This study showed that more aromatics and gas products could be obtained at a low weight hourly space velocity (WHSV) than that at high WHSV using HZSM-5 and Ni/HZSM-5 catalysts. A low WHSV offered an increased tendency to build up aromatics and paraffins. Real bio-ethanol broth was tested and gave the similar result as pure ethanol solution. That catalysts could retain full catalytic activity after 168 h in reaction provides evidence for their long stability. This study advantageously demonstrates a promising approach to generate high-value products from bio-ethanol.

The single‐step syngas‐to‐dimethyl ether (STD) process entails economic and technical advantages over the current industrial two‐step process. Pd/ZnO‐based catalysts have recently emerged as interesting alternatives to currently used Cu/ZnO/Al2O3 catalysts, but the nature of the active site(s), the reaction mechanism, and the role of Pd and ZnO in the solid catalyst are not well established. Now, Zn‐stabilized Pd colloids with a size of 2 nm served as the key building blocks for the methanol active component in bifunctional Pd/ZnO‐γ‐Al2O3 catalysts. The catalysts were characterized by combining high‐pressure operando X‐ray absorption spectroscopy and DFT calculations. The enhanced stability, longevity, and high dimethyl ether selectivity observed makes Pd/ZnO‐γ‐Al2O3 an effective alternative system for the STD process compared to Cu/ZnO/γ‐Al2O3., Zinc‐stabilized palladium colloids with a size of about 2 nm are the key building units for bifunctional syngas‐to‐dimethyl ether catalysts with enhanced stability, longevity, and high dimethyl ether selectivity. The catalysts were characterized by combining high‐pressure operando X‐ray absorption spectroscopy and DFT calculations.

The hydrothermal base-catalysed treatment of industrial Kraft lignin (KL) is investigated as a basis for production of a sustainable carbon fibre precursor, with a focus on the time-dependent evolution and impact on precursor properties. Hydrothermal treatment was performed at T = 300 °C and p = 180 bar, with the retention time (t) varied between 8, 12, 16, 20, and 24 mins. Molecular weight distribution and thermal stability of the processed lignin were close to maximum after 8 min, and 12–16 min respectively. Chemical modification was found to continue (e.g. demethoxylation) over the entire t range (24 min). Analysis of the recovered oily phase indicated catechol derivatives were stable end-products with, e.g., vanillin and guaiacol as intermediates. A techno-economic analysis indicated a price of ca. 1600 €/t at a production capacity of 10 kt/a is achievable, with main cost-drivers being lignin (60%), fixed costs (20%), and energy (10%)., 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 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 measurement

Well-defined colloidal Cu/Zn-based nanoparticles were synthesized and employed as precursors for the methanol active component in bifunctional syngas-to-dimethyl ether (STD) catalysts. The experiments were conducted using simulated biomass-derived, CO-rich syngas (H2 : CO ratio of 1 : 1) in a single continuous-flow reactor by combining the two catalytically active components (i.e., Cu/ZnO for methanol synthesis and γ-Al2O3 for its subsequent dehydration). Two different synthetic pathways were developed for synthesizing the colloidal Cu/Zn-based nanoparticles, while ensuring close contacts between the Cu nanoparticles and the Zn phase. Pure Cu nanoparticles were used as a reference. A series of bifunctional STD catalysts was prepared, where the nanoparticles were either directly supported on the dehydration catalyst or integrated into the STD catalyst by physical mixing. With this approach, active catalysts for the STD reaction with high DME selectivity were obtained.

Bio-fuels of the 2nd generation constitute a key approach to tackle both Greenhouse Gas (GHG) and air quality challenges associated with combustion emissions of the transport sector. Since these fuels are obtained of residual materials of the agricultural industry, well-totank CO2 emissions can be significantly lowered by a closed-cycle of formation and absorption of CO2. Furthermore, studies of bio-fuels have shown reduced formation of particulate matter on account of the fuels’ high oxygen content therefore addressing air quality issues. However, due to the high oxygen content and other physical parameters these fuels are expected to exhibit different ignition behaviour. Moreover, the question is whether there is a positive superimposition of the fuels ignition behaviour with the benefits of an alternative ignition system, such as a corona ignition. To shed light on these questions two oxygenic compounds, oxymethylene ether-1 (OME1) and dimethyl carbonate (DMC) have been studied with respect to OH* emission throughout ignition and onset of flame-front propagation in a combustion chamber with a large optical access via a quartz window. OH* measurements have been recorded via a highspeed optical camera (5 kHz) coupled with 308 nm optical filter and image intensifier. Sealing material swelling tests have yielded a perfluoroelastomer (FFKM 72) as an ideal, cost-efficient material regardless of the applied fuel. Comparative measurements with both ignition systems for combustion of gasoline as well as moderate blend admixtures of OME1 and DMC have demonstrated the superior ignition stability with likewise implications on flame-kernel development for the corona ignition. Furthermore a strong influence of the mode of discharge on OH* formation rates was observed especially for the oxygenic blends. Finally, for admixture variations of both oxygenates, an increased OH* level was shown during discharge thereby proving the hypothesis of a positive superimposition of oxygenic fuel and corona ignition system.

The majority of platform chemicals are currently provided through crude oil processes. Nevertheless, the substitution of the crude oil with biomass should be the ecological aim. Lignin, an aromatic macromolecule, may play an important role in that exchange, as it is the only bio based source of aromatic compounds. For instance, it could be a source of bifunctional aromatic molecules, like the monocyclic compounds catechol or guaiacol, or bifunctional oligomers. However, no process for the production of aromatics from lignin in technical scale has been established until now. Hence, the focus of this work is to clarify the chemical degradation mechanism under hydrothermal conditions, to liquefy lignin delivering high functional molecules and to increase the yield and selectivity of the cleavage towards bifunctional molecules like catechol. The combination of fast hydrolysis, thermal degradation reactions and hydrogenation drives the hydrothermal liquefaction; this gives the possibility to narrow down the product spectrum in comparison to other “dry” cleavage methods, towards a higher yield of e.g. catechols.