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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.

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.

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.

The isomerization of glucose-containing hydrolysates to fructose is a key step in the process from lignocellulosic biomass to the platform chemical hydroxymethylfurfural. We investigated the isomerization reaction of glucose to fructose in water catalyzed by hydrotalcite. Catalyst characterization was performed via IR, XRD, and SEM. Firstly, glucose solutions at pHneutral conditions were converted under variation of the temperature, residence time, and catalyst loading, whereby a maximum of 25 wt.% fructose yield was obtained at a 38 wt.% glucose conversion. Secondly, isomerization was performed at pH = 2 using glucose solutions as well as glucose-containing hydrolysates from lignocellulosic biomass. Under acidic conditions, the hydrotalcite loses its activity for isomerization. Consequently, it is unavoidable to neutralize the acidic hydrolysate before the isomerization step with an inexpensive base. As a neutralizing agent NaOH is preferred over Ba(OH)2, since higher fructose yields are achieved with NaOH. Lastly, a pH-neutral hydrolysate from lignocellulose was subjected to isomerization, yielding 16 wt.% fructose at a 32 wt.% glucose conversion. This work targets the application of catalytic systems on real biomass-derived samples.

Within the so-called bioliq® process, renewable carbon resources, especially agricultural residues, are converted to gasoline. The process chain comprises pyrolysis of the feedstocks, gasification to synthesis gas, gas cleaning and conversion of synthesis gas to dimethyl ether (DME) followed by conversion of DME to hydrocarbons. Construction of all process units has been completed now and the entire plant has been successfully operated in several campaigns. Thus, hundreds of liters of a new alternative gasoline are available now, which allow for an extensive testing. The basic characteristics of the resulting bioliq®/100 fuel are described. It is rich in aromatics and a blend consisting of 90 Vol.−% of conventional RON95 E5 fuel and 10 Vol.−% of bioliq®/100, designated as bioliq®/10, has been produced which meets the DIN EN 228 standard. Initial measurements on a single cylinder research engine have been carried out focusing on efficiency and emissions. A comparison of bioliq®/10 with neat RON95 E5 revealed an improved knocking behavior of bioliq®/10 even by a small fraction of regenerative bioliq® fuel. Particle as well as hydrocarbon emissions from bioliq®/10 are significantly higher than in the case of RON95 E5. Increased particle emissions are attributed to the higher content of aromatics. Soot reactivity has been investigated and soot from bioliq®/10 exhibits higher reactivity than soot from RON95 E5.

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

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.

For the single step synthesis of dimethyl ether (DME) from synthesis gas a Cu/ZnO/Al 2 O 3 -catalyst has been prepared using flame-spray pyrolysis. The resulting powder was co-mixed with γ-alumina to give an admixed system for DME production. The flame-made catalyst was analyzed using the BET method, in situ XRD, N 2 O decomposition, TPR and XPS. These studies unraveled that the catalyst exhibited a high Cu surface area including good contact with zinc oxide and alumina as well as small Cu particles resulting in high catalytic activity and product selectivity, also in comparison to a commercially available catalyst.

The transcription factor of the cyclic AMP receptor protein/FNR family, NtcA, and the P II signaling protein play central roles in global nitrogen control in cyanobacteria. A dependence on P II for NtcA-regulated transcription, however, has not been observed. In the present investigation, we examined alterations in gene expression following nitrogen deprivation in Synechococcus elongatus strain PCC 7942 and specifically the roles of NtcA and P II . Global changes in de novo protein synthesis following combined-nitrogen deprivation were visualized by in vivo [ 35 S]methionine labeling and two-dimensional polyacrylamide gel electrophoresis analysis. Nearly all proteins whose synthesis responded specifically to combined-nitrogen deprivation in wild-type cells of S. elongatus failed to respond in P II - and NtcA-deficient mutants. One of the proteins whose synthesis was down-regulated in a P II - and NtcA-dependent manner was RbcS, the small subunit of RubisCO. Quantification of its mRNA revealed that the abundance of the rbcLS transcript following combined-nitrogen deprivation rapidly declined in wild-type cells but not in P II and NtcA mutant cells. To investigate further the relationship between P II and NtcA, fusions of the promotorless luxAB reporter genes to the NtcA-regulated glnB gene were constructed and these constructs were used to transform wild-type cells and P II − and NtcA − mutants. Determination of bioluminescence under different growth conditions showed that NtcA represses gene expression in the presence of ammonium in a P II -independent manner. By contrast, NtcA-dependent activation of glnB expression following combined-nitrogen deprivation was impaired in the absence of P II . Together, these results suggest that under conditions of combined-nitrogen deprivation, the regulation of NtcA-dependent gene expression requires the P II signal transduction protein.

We report the cloning and sequencing of the glnN gene encoding a class III glutamine synthetase from the cyanobacterium Synechococcus strain PCC 7942. Mapping of the transcriptional start site revealed a DNA sequence in the promoter region that resembles an imperfect NtcA binding motif. Expression of glnN is impaired in NtcA- and P II -deficient mutants. The only parameter which was negatively affected in the glnN mutant compared to the wild type was the recovery rate of prolonged nitrogen-starved cells with low concentrations of combined nitrogen.