Achim Schaadt

The Influence of the Precipitation/Ageing Temperature on a Cu/ZnO/ZrO2 Catalyst for Methanol Synthesis from H2 and CO2

For heterogeneous catalysts, the constitution of the precursor is an important parameter to adjust the properties of the active catalyst. Therefore, we examined the influence of the temperature during the precipitation process and during the ageing time in the mother liquor for a Cu/ZnO/ZrO2 catalyst system obtained through a coprecipitation route. The variation of the temperature affects the ratio and crystallinity of the precursor phases zincian malachite and aurichalcite, as detected by powder XRD (phase and line width) and FTIR spectroscopy (characteristic asymmetric CO stretching modes of the carbonate anions at

Poly(oxymethylene) dimethyl ether synthesis – a combined chemical equilibrium investigation towards an increasingly efficient and potentially sustainable synthetic route

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Economics & carbon dioxide avoidance cost of methanol production based on renewable hydrogen and recycled carbon dioxide – power-to-methanol

=1600–1100 cm−1). Therefore, the precatalyst surface area (As,BET) and pore distribution are adjustable (i.e., As,BET of 190 m2 g−1 was reached). The influence of the synthesis conditions on the catalysts activity for methanol production was analyzed and discussed up to the level of productivity/activity testing at 413/513 K and 40 bar total H2/CO2 pressure. The best catalyst showed a methanol productivity of 9.16 mmol gcat−1 h−1 (513 K, 40 bar, and gas hourly space velocity=8000) and is better than an industrial catalyst tested under the same conditions (8.34 mmol gcat−1 h−1). However, despite considerable differences in the precursor and precatalyst structure and morphology, their influence on the methanol productivity is only small. This demonstrates that the active catalyst is formed under reaction conditions.

Bio-electrochemical conversion of industrial wastewater-COD combined with downstream methanol synthesis – an economic and life cycle assessment

Polyoxymethylene dimethyl ethers (denoted hereon as OME) are potential sustainable fuels (e.g. as a diesel substitute). In this paper, the fundamental analysis of a potentially, sustainable synthetic OME system is presented (i.e. based on CH3OH synthesised from H2 and recycled CO2). In this context, a multicomponent thermodynamic vapour–liquid equilibrium model, based on CH3OH as the educt and source of H2CO for OME synthesis, is described. A thermodynamic equilibrium mathematical model for this complex (i.e. a 29 reaction network) CH3OH–H2CO equilibrium system is presented, capable of solving the sequential chemical and phase equilibrium, importantly considering all components in the reaction system including poly(oxymethylene) hemiformals and poly(oxymethylene) glycols. A theoretical efficiency evaluation indicates that the proposed anhydrous route is potentially more attractive than the conventional synthesis (i.e. based on dimethoxymethane and trioxane). To substantiate these theoretical investigations, a complimentary experimental batch OME synthesis is also presented, providing validation for the presented thermodynamic model. An initial kinetic analysis of the OME synthesis over different commercial catalysts is also highlighted. Our presented findings reliably describe the synthesis equilibrium with respect to our experimentally obtained results. The presented work supports further an operating OME synthesis framework based on CH3OH and H2CO and highlights the requirement for innovative process design regarding feed preparation, reactor technology, and product separation/fractions recycling.

Towards a Sustainable Synthesis of Oxymethylene Dimethyl Ether by Homogeneous Catalysis and Uptake of Molecular Formaldehyde

The synthesis of sustainable methanol based on renewable electricity generation, sustainable hydrogen (H2) and recycled carbon dioxide (CO2) represents an interesting sustainable solution to integrated renewable energy storage and platform chemical production. However, the business case for this electricity based product (denoted hereafter as eMeOH) under current market conditions (e.g. vs. conventional fossil methanol (fMeOH) production cost) and the appropriate implementation scenarios to increase platform attractiveness and adoption have to be highlighted. The aim of the following study was to perform a dynamic simulation and calculation of the cost of eMeOH production (where electricity is generated at a wind park in Germany), with comparison made to grid connected scenarios. Consideration of these scenarios is made with particular respect to the German energy market and potential for the reduction in fees/taxes (i.e. for electrolyser systems). This evaluation and indeed the results can be viewed in light of European Union efforts to support the implementation of such technologies. In this context, CO2 is sourced from EU relevant sources, namely a biogas or ammonia plant, the latter profiting from the resulting credit arising from CO2 certificate trading. Variation in electricity cost and the CO2 certificate price (in the presented sensitivity study) demonstrate a high cost reduction potential. Under the energy market conditions of Germany it is found that eMeOH production costs vary between €608 and 1453 per tonne based on a purely grid driven scenario, whilst a purely wind park supplied scenario results in €1028–1067 per tonne. The reported results indicate that the eMeOH production cost in Germany is still above the present (although variable) market price, with the economical evaluation indicating that electrolyser and H2 storage represent the lion share of investment and operational cost. Substitution of fMeOH results in CO2 avoidance costs between €365 and 430 per tonne of CO2eq avoided for green methanol produced in Germany. The presented assessment indicates that the eMeOH production cost in Germany will reach market parity in ca. 2030–2035 with the price for the avoidance of CO2eq turning from a cost to a benefit at around the same time. Optimistically, the cost is predominantly influenced by rapidly reducing renewable electricity costs as is already the case in South American and Arabic countries offering the potential for methanol production at a cost of <€500 per tonne.

A catalytic evaporation process for in-cylinder soot and NO x reduction in internal combustion engines

Herein, a techno-economic and environmental performance evaluation (i.e. Life Cycle Assessment (LCA)) of a 45 kW Microbial Electrolysis Cell (MEC) system is presented in the context of industrial wastewater remediation. This system produces H2 and CO2 – suitable for downstream CH3OH synthesis – based on the bio-electrochemical conversion of chemical industry wastewater with an organic content of 3.9 g(COD) L−1. A cost–benefit analysis indicates that the MEC system hardware costs, share of CO2 captured from the MEC and MEC operating current density (i.e. 1.0 mA cm−2) are crucial parameters influencing the total cost and represent areas for potential cost reductions. It was established based on the present study that MEC system operation with renewable electricity leads to H2 production costs of 4–5.7€ kg(H2)−1 (comparable to H2O electrolysis) and CH3OH production costs of 900€ t(CH3OH)−1. At the current CH3OH market prices, however, the production is currently not profitable. In turn, the cost-efficient construction of the MEC system and the use of less expensive materials could lead to improved CH3OH production economics based on this route. Our results indicate that the use of low-cost materials has greater potential with regard to cost reduction compared to reducing the internal resistance and polarization losses via the use of expensive high-performance materials in MEC construction. A complementary LCA of the proposed system, based on a “cradle-to-gate” definition, indicates that waste-based is superior to fossil-based CH3OH production with respect to global warming potential and cumulated fossil energy demand, provided the system is operated with 100% renewable electricity and CO2 sourced only from the MEC. However, with regard to the impact categories Metal Depletion and Freshwater Eutrophication Potential, the system was found to perform less satisfactorily (i.e. in comparison with fossil-based CH3OH production).

Synthesis and preliminary gas permeation studies of a tubular NaA zeolite membrane (NZM)

Oxymethylene dimethyl ethers (OMEn ; CH3 (-OCH2 -)n O-CH3 , n=3-5) are a novel class of sustainable synthetic fuels, which are of increasing interest due to their soot-free combustion. Herein a novel anhydrous OMEn synthesis route is presented. Catalyzed by trimethyloxonium salts, dimethoxymethane takes up monomeric gaseous formaldehyde instantaneously and forms high purity OMEn at temperatures of 25-30 °C. This new anhydrous approach using molecular formaldehyde and catalytic amounts of highly active trimethyloxonium salts represents a promising new step towards a sustainable formation of OMEn emanating from CO2 and H2 .

A portable fuel processor for hydrogen production from ethanol in a 250 Wel fuel cell system

In this work, a novel catalytic evaporator was tested in a single-cylinder Heavy-Duty Diesel engine in order to achieve low NOx and soot emissions as well as to control the combustion phase for homogeneous Low-Temperature Combustion (LTC). Conventionally, two fuels with different ignition properties are used to control the combustion phasing, however in this study only diesel is used. As a consequence of our presented approach, the ignition properties of the fuel vapour can be adjusted by changing the operating parameters of the catalytic evaporator.

Palladium/ruthenium composite membrane for hydrogen separation from the off-gas of solar cell production via chemical vapor deposition

ABSTRACT Different from traditional seeded method, NaA zeolite membranes (NZMs) were prepared by in situ synthesis onto the inner side of porous α-alumina tubular supports in a hydrothermal synthesis reactor. The influences of pretreatment of porous tubular support, temperature, time, and synthetic cycle for the synthesis of the zeolite membranes were investigated. The operating conditions were optimized. Characterization of the membranes by scanning electron microscopy and X-ray diffraction showed that the crystalline materials on the inner surface of the porous α-alumina tubes were NaA-type zeolite. Single- and binary-gas permeation tests were conducted. Single-component permeabilities of hydrogen and nitrogen through the NZM changed slightly when the transmembrane pressure difference varied from 80 to 420 kPa. Its selectivity for H2 relative to N2 was about 5.3, which was greater than that of the Knudsen diffusion. The separation factors of binary gases H2/N2 and H2/CO2 at 473 K were 3.9 and 5.7, respectively, again exceeding the Knudsen diffusion level. The separation of binary gases suggests that the NaA-type zeolite membranes on α-alumina substrate were defect free and able to provide molecular sieving. The results demonstrate that the unseeded synthetic method presented in this work is successful and reliable.