The detection of silica-rich dust particles, as an indication for ongoing hydrothermal activity, and the presence of water and organic molecules in the plume of Enceladus, have made Saturn's icy moon ...a hot spot in the search for potential extraterrestrial life. Methanogenic archaea are among the organisms that could potentially thrive under the predicted conditions on Enceladus, considering that both molecular hydrogen (H
) and methane (CH
) have been detected in the plume. Here we show that a methanogenic archaeon, Methanothermococcus okinawensis, can produce CH
under physicochemical conditions extrapolated for Enceladus. Up to 72% carbon dioxide to CH
conversion is reached at 50 bar in the presence of potential inhibitors. Furthermore, kinetic and thermodynamic computations of low-temperature serpentinization indicate that there may be sufficient H
gas production to serve as a substrate for CH
production on Enceladus. We conclude that some of the CH
detected in the plume of Enceladus might, in principle, be produced by methanogens.
The conversion of lignocellulosic biomass into value-added chemicals and biofuels has been attracting the attention of researchers in recent years. Lignin is an abundant, natural polymer and a major ...component of lignocellulose comprising an aromatic structure with ether linkages, methoxy-, and hydroxyl groups. Therefore, it has great potential as a sustainable source to produce basic chemical products. In this study, precious metal-loaded hydrotalcite (HTC) catalysts for the depolymerization of organosolv lignin (OL) were investigated concerning minimizing coke formation and maximizing the value-added lignin oil fraction and lignin tar fraction. The influences of the catalyst support, the platinum loading as well as the loading with a second metal (Cu or Ni) were examined. The resulting depolymerization fractions (lignin oil, lignin tar, aqueous fraction, and coke) were determined gravimetrically. To compare the molecular mass distribution of the lignin oil and lignin tar fractions as well as the purchased OL, gel permeation chromatography (GPC) was used. The lignin oil fractions were analyzed quantitatively and qualitatively by gas chromatography-mass spectroscopy (GC–MS). Regarding the most suitable catalyst system (5%Pt-1%Ni/HTC), a design of experiment (DoE) was prepared to further minimize coke formation and maximize the value-added fractions (lignin oil and lignin tar). This optimization led to 18 wt% lignin oil fraction, 72 wt% lignin tar fraction, and 0.4 wt% coke formation.
•Process optimization for the depolymerization of organosolv lignin using DOE, response surface methodology.•Influences of catalyst support (hydrotalcite, HTC), platinum loading and loading with a second metal (Cu or Ni) were examined.•Maximization of yields of lignin tar and oil product fractions while minimizing coke formation and required catalyst amount.•The yields of value-added products could be increased to about 90% under the optimized process conditions with 5%Pt-1%Ni/HTC.•The depolymerization was carried out in ethanol/water as solvent and H-donor.
We present a techno-economic assessment of a novel ethylene oxide (EO) production process, which converts carbon dioxide (CO2) and water electrocatalytically to ethylene (C2H4) and hydrogen peroxide ...(H2O2), which are further synthesized into EO. To ensure environmental sustainability, the primary focus was on available CO2 from biogenic sources (biomethane and bioethanol plants) and renewable power sources (wind and photovoltaics) for decentralized applications. Accordingly, data on existing European CO2 and renewable power sources were compiled for spatial analysis to develop technology roll-out and exploitation scenarios: 175 suitable locations were identified. Focusing on three locations, the production costs of EO and the product mix were calculated, considering various energy sources and plant configurations (as of 2030 and 2040). For a generic scenario, considering CO2 to be available free of cost (existing biomethane upgrading) and electricity cost of 36€/MWh, the production cost of the product mix (EO, H2O2, methane, hydrogen) amount to 0.86 €/kg. This is at a similar order of magnitude as assessments on other Power-to-X value chains. Assuming that EO is the only utilizable product, the costs increase to 5.78 €/kg, which is significantly higher than for fossil alternatives. According to the sensitivity analysis, energy efficiency, electricity prices, and capital expenditure are the most relevant factors. Regarding the latter, an extended plant lifetime is a crucial factor.
•Techno-economic assessment of a CO2-based ethylene oxide production route.•Levelized cost of production of 0.35–5.78 €/t depending on scenario.•Critical factors: energy efficiency & prices, plant lifetime, capital expenditure.•162 potential sites with biogenic CO2 & renewable power identified for EU.•Biogenic CO2 capture must be significantly increased to cover demand.
,
-diphenylacenaphthylene-1,2-diimines (BIANs) have been used to reduce the undesired high viscosity of alkyl magnesium solutions, which are known to form polymeric structures. In order to understand ...the mechanisms, analyses of the BIAN alkyl magnesium solutions have been carried out under inert conditions with SEC-MS, NMR, and FTIR and were compared to the structures obtained from HPLC-MS, FTIR, and NMR after aqueous workup. While viscosity reduction was shown for all BIAN derivatives used, only the bis (diisopropyl)-substituted BIAN could be clearly assigned to a single reaction product, which also could be reused without loss of efficiency or decomposition. All other derivatives have been shown to behave differently, even under inert conditions, and decompose upon contact with acidic solvents. While the chemical reactions observed after the workup of the used BIANs are dominated by (multiple) alkylation, mainly on the C = N double bond, the observation of viscosity reduction cannot be assigned to this reaction alone, but to the interaction of the nitrogen atoms of BIANs with the Mg of the alkyl magnesium polymers, as could be shown by FTIR and NMR measurements under inert conditions.
Recycling of plastic materials is a key sustainability topic. Hence, the scope of this study is to evaluate the potential of this purification step for achieving high-purity recyclates via mechanical ...recycling. In this study, the focus is set on the revalorization of poly(3-hydroxy butyrate) and poly(3-hydroxy butyrate-co-3-hydroxy valerate)—two biobased and biodegradable polymers that have properties similar to those of polyolefins and are therefore possible eco-friendly alternatives. Specifically, the washing process as an important part of polymer recycling processes is evaluated regarding different washing conditions on a laboratory scale. For this purpose, several virgin polymers were contaminated with volatile organic compounds that differed in functionality and molecular weight. Regarding contamination, concentration correlates with contamination time. Moreover, the contamination degree was found to be higher for polar contaminants since polar compounds show higher compatibility with the polymer. General beneficial effects of higher temperatures and longer washing times were observed. The choice of washing medium was relevant for different polarities of the contaminants. At higher process temperatures, material degradation occurred. Hence, recyclers have to pay attention to the difference in the interaction between impurities and the polymer and to the degradation of the polymer during recycling and the subsequent formation of degradation products. Since these biopolymers display comparable properties to polyolefins, great potential in packaging applications is apparent. Moreover, the method of analyzing the removal efficiency of volatile organic compounds via washing can be applied to all recyclable polymers.
A facile approach to obtaining cellulose nanofiber-reinforced polystyrene with greatly improved mechanical performance compared to unreinforced polystyrene is presented. Cellulose nanofibers were ...obtained by mechanical fibrillation of partially delignified wood (MFLC) and compared to nanofibers obtained from bleached pulp. Residual hemicellulose and lignin imparted amphiphilic surface chemical character to MFLC, which enabled the stabilization of emulsions of styrene in water. Upon suspension polymerization of styrene from the emulsion, polystyrene microspheres coated in MFLC were obtained. When processed into polymer sheets by hot-pressing, improved bending strength and superior impact toughness was observed for the polystyrene–MFLC composite compared to the un-reinforced polystyrene.
In this study the leaching of a one component (1K) structural epoxy model adhesive for the automotive industry is analysed via fourier transform infrared spectroscopy (FT-IR). In addition, the ...gravimetric water uptake and morphological changes were observed.
Findings indicate a two-stage water absorption at room temperature, whereas at 70 °C the water absorption shows a drastically increased value including a loss of mass after 500 h of immersion in DI-water. Water content at ambient conditions shows a dependency of the absolute humidity. FT-IR analyses of the dried eluate originating from immersion at 23 °C reveals typical bands of the latent hardener dicyandiamide and the filler CaCO3. On the other hand, the spectrum of the eluate originating from immersion at 70 °C exhibits bands of the fumed silica used as rheological additive. Microscopical observation by means of scanning electron microscopy (SEM) of the adhesive reveals that cavities arise in the vicinity of the inorganic particles contained in the adhesive due to water uptake.
•A novel, near to realism structural epoxy adhesive for scientific purposes.•Gravimetric water uptake in structural epoxy adhesive.•Leaching of substances.•Morphological changes upon water uptake.
Carbon capture and utilization (CCU) technologies support future energy and climate transition goals by recycling carbon dioxide (CO
2
) emissions. The use of biogenic CO
2
from renewable sources, is ...an avenue for the production of fully renewable products. Fossil-based materials can potentially be replaced in the long term while allowing for the use of so called “waste” streams. To foster the development of a circular economy more insights need to be gained on the life cycle impact of CCU technologies. This study analyzed a CCU process chain, with focus on the utilization of volatile renewable electricity and biogenic CO
2
. We performed a cradle-to-gate life cycle assessment, evaluating various environmental impact categories (CML 2001 methodology) and primary energy demand (PED) with GaBi LCA software by sphera
®
. The targeted olefin is ethylene oxide (C
2
H
4
O), which is a crucial intermediate chemical for the production of various synthetic materials, such as polyethylene terephthalate (PET). As functional unit, 1 kg ethylene oxide was chosen. In the novel process at first ethylene (C
2
H
4
) and hydrogen peroxide (H
2
O
2
) are produced from water and CO
2
via
an electrocatalytic process (Power-to-X process). In a second step, the two intermediates are synthesized to ethylene oxide. The theoretical implementation of a medium-scale process under average European conditions was considered in 12 scenarios that differed in energy supply and CO
2
source. Sensitivity analyses were conducted to evaluate the influence of the energy and resource efficiencies of the production steps. The process was compared to its fossil benchmark, an existing conventional EO production chain. Concerning the global warming potential (GWP), negative emissions of up to −0.5 kg CO
2
eq./kg product were calculated under optimized process conditions regarding energy and conversion efficiency and using biogenic CO
2
. In contrast, the GWP exceeded the fossil benchmark when the European grid mix was applied. The PED of 87 MJ/kg product under optimized conditions is comparable to that of other Power-to-X processes, but is high compared to fossil-based ethylene oxide. Based on the results we conclude that the energy efficiency of the electrocatalytic cell and renewable energy as input are the main levers to achieve a low environmental impact.
The large range of polymers produced leads to their use in such diverse areas as packaging, the automotive industry, electrical applications, electronics, household appliances, building, and ...construction. For these applications, materials should be clean and free from contaminants, such as unintentionally cross‐linked material (gels), unconverted polymers, agglomerated additives, dirt, and dust. Since 2000, the amount of plastic produced globally has increased by 5% per year. In 2019, Europe consumed 50.7 million tonnes of plastics, and demand is increasing. As production rises, so does waste, making it essential to reduce plastic waste via recycling. To be recycled, materials must be clean and free from contaminants. While numerous preparation processes in recycling can reduce contamination, the final remaining contaminants can be separated from the polymer by melt filtration. The aim of this work was thus to gain insights into the mechanisms underlying melt filtration in an extruder to determine how effective the process is depending on the type of contamination (PET particles and glass beads served as model contaminants). Additionally, behavior and filtration efficiency of two different screen‐pack types were investigated. We found that rigid contaminants (i.e., glass beads) can be filtered from the melt by using screens that are finer than the particle size, but removing soft contaminants, (i.e., PET particles) requires even finer.
Schematic work‐flow of melt filtration experiments with melt filtration trials using different screens, recording of pressure vs time curves and microscopic investigations of screen before and after.
PDF
