Renewable fuels for sustainable electricity production

Scientists involved in the National Research Programme's joint project "Reduction and Reuse of CO2: Renewable Fuels for Electricity Production" joint project in Switzerland are testing innovative ways to reutilise waste resources of carbon dioxide, harness energy from the sun and produce electricity with zero carbon emissions. Dr Andre Heel is the leader of the joint project NRP70 that is developing more sustainable solutions for electricity and heat production

A cost estimation for CO2 reduction and reuse by methanation from cement industry sources in Switzerland

The Swiss government has signed the Paris Climate Agreement and various measures need to be implemented in order to reach the target of a 50% reduction in CO2 emissions in Switzerland by 2030 compared with the value for 1990. Considering the fact that the production of cement in Switzerland accounts around 2.5 million ton for CO2 emissions of which corresponds to roughly 7% of the country’s total CO2 emissions, the following article examines how this amount could be put to meaningful use in order to create a new value-added chain through CO2 methanation, and thus reduce the consumption and import of fossil fuels in Switzerland. With power-to-gas technology, this CO2, along with regenerative hydrogen from photovoltaics, can be converted into methane, which can then be fed into the existing natural-gas grid. This economic case study shows a cost prediction for conversion of all the CO2 from the cement industry into methane by using the technologies available today in order to replacing fossil methane imports

Flame spray synthesis and characterisation of stabilised ZrO2 and CeO2 electrolyte nanopowders for SOFC applications at intermediate temperatures

Zirconia (Y0.16Zr0.84O2, Sc0.2Zr0.8O2 and Sc0.2Ce0.01Zr0.79O2) and ceria (Gd0.2Ce0.8O2) based electrolyte materials are synthesised at production rates up to 260g h−1 by a liquid-fed one-step flame spray synthesis from water-based solutions, or cost-effective rare earth nitrates with a high water content. It was found that this one-step synthesis, based on an acetylene-supported flame is able to produce phase pure and highly crystalline, nanoscale electrolyte materials. The as-synthesised powders show a cubic lattice structure independent of production rates. Specific surface areas of the powders were adjusted between 20 and 60m2 g−2, where the latter is an upper limit for the further processing of the powders in terms of screen printing. The influence of process parameters on morphology, particle size, composition, crystallinity, lattice parameter, shrinkage behaviour and coefficient of thermal expansion of the as-synthesised powders were systematically investigated by transmission electron microscopy (TEM), nitrogen adsorption (BET), X-ray diffraction (XRD) and dilatometry. Electrochemical impedance spectroscopy (EIS) was applied at temperatures between 300°C and 900°C and confirmed the high quality and the competitive electrochemical behaviour of the produced powder

Are Fe based catalysts an upcoming alternative to Ni in CO2 methanation at elevated pressure?

The raise of regenerative but unsteadily produced energy demands a highly flexible way to store the energy for time periods when less energy is produced than consumed. In the current study, it is investigated if catalysts based on environmentally more attractive and less hazardous to health Fe might be able to be considered as an alternative to Ni catalysts in the CO2 methanation at elevated pressure. For this a set of catalysts with 1–10 wt % Fe supported on the zeolite 13X is analysed in CO2 methanation at 1–15 bar. The trends of activity as well as selectivity with varying Fe loading and pressure are presented. Correlation with thorough characterization of the materials shows that a very high dispersion of Fe in octahedral sites within the zeolite is necessary to generate CH4 as the main reaction product and suppress the Fischer–Tropsch activity towards Csingle bondC coupling reactions at elevated pressure. Especially with low Fe loading such as 1 wt % high reaction rates of 42 mmol(CO2)/(mol(Fe)∙s) with a CH4 selectivity of 76 % at 300 °C and 10 bar are obtained. In contrast to that, highly Fe loaded catalysts tend to form increasing amounts of Fischer–Tropsch products at increasing pressure. In addition, highly Fe-loaded catalysts are much more susceptible to destruction of the zeolite under reaction conditions. At the same time, highly loaded catalysts form a Fe3C shell around the remaining support. Hence, avoiding the formation of a Fe3C phase is crucial for high CH4 selectivity. The results presented here therefore show that catalysts with a very high Fe-dispersion in particular can gain considerably in importance as alternatives to Ni-methanation catalysts at elevated pressure

Evolution of water diffusion in a sorption-enhanced methanation catalyst

Sorption-enhanced methanation has consequent advantages compared to conventional methanation approaches; namely, the production of pure methane and enhanced kinetics thanks to the application of Le Châtelier’s principle. In this paper, we address the question of the long-term stability of a sorption-enhanced methanation catalyst-support couple: Ni nanoparticles on zeolite 5A. Compared to most conventional methanation processes the operational conditions of sorption-enhanced methanation are relatively mild, which allow for stable catalyst activity on the long term. Indeed, we show here that neither coking nor thermal degradation come into play under such conditions. However, a degradation mechanism specific to the sorption catalysis was observed under cyclic methanation/drying periods. This severely affects water diffusion kinetics in the zeolite support, as shown here by a decrease of the water-diffusion coefficient during multiple cycling. Water diffusion is a central mechanism in the sorption-enhanced methanation process, since it is rate-limiting for both methanation and drying

Effect of Nb doping on structural, optical and photocatalytic properties of flame-made TiO2 nanopowder

TiO2:Nb nanopowders within a dopant concentration in the range of 0.1-15at.% were prepared by one-step flame spray synthesis. Effect of niobium doping on structural, optical and photocatalytic properties of titanium dioxide nanopowders was studied. Morphology and structure were investigated by means of Brunauer-Emmett-Teller isotherm, X-ray diffraction and transmission electron microscopy. Diffuse reflectance and the resulting band gap energy were determined by diffuse reflectance spectroscopy. Photocatalytic activity of the investigated nanopowders was revised for the photodecomposition of methylene blue (MB), methyl orange (MO) and 4-chlorophenol under UVA and VIS light irradiation. Commercial TiO2-P25 nanopowder was used as a reference. The specific surface area of the powders was ranging from 42.9m2/g for TiO2:0.1at.% Nb to 90.0m2/g for TiO2:15at.% Nb. TiO2:Nb particles were nanosized, spherically shaped and polycrystalline. Anatase was the predominant phase in all samples. The anatase-related transition was at 3.31eV and rutile-related one at 3.14eV. TiO2:Nb nanopowders exhibited additional absorption in the visible range. In comparison to TiO2-P25, improved photocatalytic activity of TiO2:Nb was observed for the degradation of MB and MO under both UVA and VIS irradiation, where low doping level (Nb < 1at.%) was the most effective. Niobium doping affected structural, optical and photocatalytic properties of TiO2. Low dopant level enhanced photocatalytic performance under UVA and VIS irradiation. Therefore, TiO2:Nb (Nb < 1at.%) can be proposed as an efficient selective solar light photocatalys

Sulphur tolerant diesel oxidation catalysts by noble metal alloying

A series of Mn-alloyed Pt supported catalysts were investigated for the NO oxidation reaction applied in diesel oxidation catalysts under sulphur-containing conditions. The observed NO oxidation conversion correlated to the Pt amount in the catalyst under sulphur-free conditions. In the presence of SO2 in the feed, the Pt/Al2O3 catalyst heavily deactivated resulting in the lowest performance compared to Mn-alloyed Pt catalysts. Already small amounts of Mn improved the SO2-resistance significantly. Whilst pure Pt/Al2O3 catalyst deactivates fully within the first 30 min under NO oxidation conditions including 300 ppm SO2, an alloy with a Mn to Pt ratio of 1:1 performed with a remarkable high catalytic stability for the NO oxidation over at least 70 h under continuous testing conditions

Segregation of nickel/iron bimetallic particles from lanthanum doped strontium titanates to improve sulfur stability of solid oxide fuel cell anodes

Perovskite derived Ni catalysts offer the remarkable benefit of regeneration after catalyst poisoning or Ni particle growth through the reversible segregation of Ni from the perovskite-type oxide host. Although this property allows for repeated catalyst regeneration, improving Ni catalyst stability towards sulfur poisoning by H2S is highly critical in solid oxide fuel cells. In this work Mn, Mo, Cr and Fe were combined with Ni at the B-site of La0.3Sr0.55TiO3±δ to explore possible benefits of segregation of two transition metals towards sulfur tolerance. Catalytic activity tests towards the water gas shift reaction were carried out to evaluate the effect of the additional metal on the catalytic activity and sulfur stability of the Ni catalyst. The addition of Fe to the Ni perovskite catalyst was found to increase sulfur tolerance. The simultaneous segregation of Fe and Ni from La0.3Sr0.55Ti0.95-xNi0.05FexO3±δ (x ≤ 0.05) was investigated by temperature programmed reduction, X-ray diffraction and X-ray absorption spectroscopy and catalytic tests after multiple redox cycles. It is shown that catalytic properties of the active phase were affected likely by the segregation of Ni/Fe alloy particles and that the reversible segregation of Ni persisted, while it was limited in the case of Fe under the same conditions

Supersite of immune vulnerability on the glycosylated face of HIV-1 envelope glycoprotein gp120

A substantial fraction of broadly neutralizing antibodies (bnAbs) in certain HIV-infected donors recognizes glycan-dependent epitopes on HIV-1 gp120. Here, we elucidate how bnAb PGT 135 recognizes its Asn332 glycan-dependent epitope from its crystal structure with gp120, CD4 and Fab 17b at 3.1 Å resolution. PGT 135 interacts with glycans at Asn332, Asn392 and Asn386, using long CDR loops H1 and H3 to penetrate the glycan shield to access the gp120 protein surface. Electron microscopy reveals PGT 135 can accommodate the conformational and chemical diversity of gp120 glycans by altering its angle of engagement. The combined structural studies of PGT 135, PGT 128 and 2G12 show this Asn332-dependent epitope is highly accessible and much more extensive than initially appreciated, allowing for multiple binding modes and varied angles of approach, thereby representing a supersite of vulnerability for antibody neutralization

Implicating genes, pleiotropy, and sexual dimorphism at blood lipid loci through multi-ancestry meta-analysis

Publisher Copyright: © 2022, The Author(s).Background: Genetic variants within nearly 1000 loci are known to contribute to modulation of blood lipid levels. However, the biological pathways underlying these associations are frequently unknown, limiting understanding of these findings and hindering downstream translational efforts such as drug target discovery. Results: To expand our understanding of the underlying biological pathways and mechanisms controlling blood lipid levels, we leverage a large multi-ancestry meta-analysis (N = 1,654,960) of blood lipids to prioritize putative causal genes for 2286 lipid associations using six gene prediction approaches. Using phenome-wide association (PheWAS) scans, we identify relationships of genetically predicted lipid levels to other diseases and conditions. We confirm known pleiotropic associations with cardiovascular phenotypes and determine novel associations, notably with cholelithiasis risk. We perform sex-stratified GWAS meta-analysis of lipid levels and show that 3–5% of autosomal lipid-associated loci demonstrate sex-biased effects. Finally, we report 21 novel lipid loci identified on the X chromosome. Many of the sex-biased autosomal and X chromosome lipid loci show pleiotropic associations with sex hormones, emphasizing the role of hormone regulation in lipid metabolism. Conclusions: Taken together, our findings provide insights into the biological mechanisms through which associated variants lead to altered lipid levels and potentially cardiovascular disease risk.Peer reviewe