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1
Stoiljkovic, Dragoslav, Slobodan Jovanovic, Jovica Djordjevic und Budimir Damjanovic. „Decompositions in the production of low density polyethylene: Reasons, consequences and prevention“. Chemical Industry 61, Nr. 6 (2007): 357–63. http://dx.doi.org/10.2298/hemind0706357s.
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In the production of low density polyethylene by free radical polymerization of ethylene at high pressure, ethylene and polyethylene occasionally decompose to carbon, hydrogen and methane resulting in an enormous increase of pressure and temperature. Huge explosions occur in a polymerization reactor and in other parts of the installation. In addition to the well known reasons of decompositions, in this work it is pointed out that the polymerization under critical entropy conditions is an additional cause of explosions, which has not been recognized and elaborated in scientific literature and industrial practice.
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Maqbool, Muhammad, Toheed Akhter, Sadaf Ul Hassan, Asif Mahmood, Waheed Al-Masry und Shumaila Razzaque. „Correction: Development of a chromium oxide loaded mesoporous silica as an efficient catalyst for carbon dioxide-free production of ethylene oxide“. RSC Advances 14, Nr. 1 (2024): 445. http://dx.doi.org/10.1039/d3ra90116e.
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Correction for ‘Development of a chromium oxide loaded mesoporous silica as an efficient catalyst for carbon dioxide-free production of ethylene oxide’ by Muhammad Maqbool et al., RSC Adv., 2023, 13, 32424–32432, https://doi.org/10.1039/d3ra05858a.
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Rosner, Fabian, Mike C. Tucker, Boxun Hu und Hanna Breunig. „Techno-Economic Analysis of Electrochemical Refineries Using Solid Oxide Cells for Oxidative Coupling of Methane“. ECS Meeting Abstracts MA2023-01, Nr. 54 (28.08.2023): 322. http://dx.doi.org/10.1149/ma2023-0154322mtgabs.
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With the shift away from fossil resources, there is a need for alternative pathways to carbon-based commodities such as ethylene. The electrochemical oxidative coupling of methane (OCM) enables the synthesis of higher hydrocarbons from simple organic molecules i.e., methane and has the potential to replace conventional ethylene production in the future. However, current solid oxide OCM cell development is still in an early stage and more comprehensive system-level analyses are needed to better understand operating conditions and economics to guide research and development. For this purpose, process models and new integration strategies for the electrochemical OCM process were developed. The integration of the electrochemical OCM unit into the plant revealed to be challenging based on current solid oxide cell designs and will be discussed as part of this presentation. The performance of the OCM plant is benchmarked against current state-of-the-art ethane steam cracker plants. In this context, key performance metrics are efficiency, direct and indirect carbon dioxide emissions, power consumption, plant cost and cost of ethylene. Of particular interest are aspects of hydrogen co-production and carbon dioxide utilization as well as the impact of carbon dioxide emission factors from the grid, which have shown to be of particular importance for electrochemical processes. Moreover, critical aspects of heat integration will be discussed including fuel pre-heating, carbon deposition and thermal cell management. The analysis will provide new insights into economic cost driving factors and the impact of cell cost, current density, overpotentials and Faraday efficiency upon the cost of ethylene. Based upon this information, performance targets will be recommended that will allow electrochemical OCM to become economically competitive in a free market environment.
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Maqbool, Muhammad, Toheed Akhter, Sadaf Ul Hassan, Asif Mahmood, Waheed Al-Masry und Shumaila Razzaque. „Development of a chromium oxide loaded mesoporous silica as an efficient catalyst for carbon dioxide-free production of ethylene oxide“. RSC Advances 13, Nr. 46 (2023): 32424–32. http://dx.doi.org/10.1039/d3ra05858a.
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Shukrullah, S., N. M. Mohamed, Y. Khan, M. Y. Naz, A. Ghaffar und I. Ahmad. „Effect of Gas Flowrate on Nucleation Mechanism of MWCNTs for a Compound Catalyst“. Journal of Nanomaterials 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/3407352.
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Activation of the catalyst particles during a CVD process can be anticipated from the carbon feeding rate. In this study, Fe2O3/Al2O3 catalyst was synthesized with uniformly dispersed iron over alumina support for onward production of multiwalled carbon nanotubes (MWCNTs) in a fluidized bed chemical CVD reactor. The effect of the ethylene flowrate on catalytic activity of the compound catalyst and morphology of the as-grown MWCNTs was also investigated in this study. The dispersed active phases of the catalyst and optimized gas flowrate helped in improving the tube morphology and prevented the aggregation of the as-grown MWCNTs. The flowrates, below 100 sccm, did not provide sufficient reactants to interact with the catalyst for production of defect-free CNT structures. Above 100 sccm, concentration of the carbon precursor did not show notable influence on decomposition rate of the gas molecules. The most promising results on growth and structural properties of MWCNTs were gained at ethylene flowrate of 100 sccm. At this flowrate, the ratio of G and D intensity peaks (IG/ID) was deliberated about 1.40, which indicates the growth of graphitic structures of MWCNTs.
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Sengupta, Annesha, Prem Pritam, Damini Jaiswal, Anindita Bandyopadhyay, Himadri B. Pakrasi und Pramod P. Wangikar. „Photosynthetic Co-production of Succinate and Ethylene in a Fast-Growing Cyanobacterium, Synechococcus elongatus PCC 11801“. Metabolites 10, Nr. 6 (16.06.2020): 250. http://dx.doi.org/10.3390/metabo10060250.
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Cyanobacteria are emerging as hosts for photoautotrophic production of chemicals. Recent studies have attempted to stretch the limits of photosynthetic production, typically focusing on one product at a time, possibly to minimise the additional burden of product separation. Here, we explore the simultaneous production of two products that can be easily separated: ethylene, a gaseous product, and succinate, an organic acid that accumulates in the culture medium. This was achieved by expressing a single copy of the ethylene forming enzyme (efe) under the control of PcpcB, the inducer-free super-strong promoter of phycocyanin β subunit. We chose the recently reported, fast-growing and robust cyanobacterium, Synechococcus elongatus PCC 11801, as the host strain. A stable recombinant strain was constructed using CRISPR-Cpf1 in a first report of markerless genome editing of this cyanobacterium. Under photoautotrophic conditions, the recombinant strain shows specific productivities of 338.26 and 1044.18 μmole/g dry cell weight/h for ethylene and succinate, respectively. These results compare favourably with the reported productivities for individual products in cyanobacteria that are highly engineered. Metabolome profiling and 13C labelling studies indicate carbon flux redistribution and suggest avenues for further improvement. Our results show that S. elongatus PCC 11801 is a promising candidate for metabolic engineering.
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Nanaiah, Geeta K., und Jeffrey A. Anderson. „ELECTROLYTE LEAKAGE AND EVOLUTION OF ETHYLENE AND ETHANE FROM PEPPER LEAF DISKS FOLLOWING TEMPERATURE STRESS AND FATTY ACID INFILTRATION“. HortScience 27, Nr. 6 (Juni 1992): 683a—683. http://dx.doi.org/10.21273/hortsci.27.6.683a.
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Electrolyte leakage (EL) and ethane:ethylene ratio (EER) responses of pepper (Capsicum annuum L. Early Calwonder) leaf disks to temperature stresses were in close agreement. Midpoints of sigmoidal response curves following freezing stress were -4.6 and -4.4C for EL and EER, and 49.0 and 48.8C following high temperature stress. Evolution of ethane and EL were measured from disks infiltrated with a saturation series of 18-carbon fatty acids ranging from 0 to 3 double bonds. Only linolenic acid (18:3 n-3) stimulated ethane production and EL. In a second fatty acid experiment with 18- and 20-carbon acids with a double bond 3 (n-3) or 6 (n-6) carbons from the nonpolar end of the molecule, n-3 fatty acids stimulated more ethane than n-6 acids with the same number of carbons. Trienoic 18-carbon fatty acids stimulated more ethane than trienoic 20-carbon acids. Both 18-carbon acids yielded significantly greater EL than controls. Propyl gallate, a free radical scavenger, reduced ethane production without decreasing EL or K+ leakage.
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Khairul Salleh, Badrul Nazahan, Nardiah Rizwana Jaafar und Rosli Md Illias. „Molecular and Interactions Modelling of PETase and Its Variant with Different Types of Crosslinker in Enzyme Immobilization“. Journal of Bioprocessing and Biomass Technology 1, Nr. 1 (22.12.2022): 13–18. http://dx.doi.org/10.11113/bioprocessing.v1n1.7.
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Plastics are made from non-renewable resources and due to the tremendous production of plastics nowadays, they can lead to high levels of pollution. Biodegradation of plastic by utilizing enzymatic catalytic reaction is an environmentally friendly strategy that produce less or no negative carbon footprint. PETase from Ideonella sakaiensis (IsPETase) is an enzyme that able to degrade polyethylene terephthalate (PET), a building block of plastic. However, free enzyme has several limitations such as unstable in harsh conditions and lack of reusability. One of the strategies to overcome this drawback is through enzyme immobilization that able to improve the enzymatic properties. A suitable crosslinker is very important as it would determine the interactions of the enzymatic particles. Crosslinker should be chosen before performing the enzyme immobilization and this can be accomplished by molecular docking. Thus, the purpose of this research is to determine the suitability of glutaraldehyde, chitosan, dialdehyde starch (DAS) and ethylene glycol as the crosslinker for IsPETase and its variant. Three-dimensional structure of the enzymes was built and docked with different types of crosslinkers. Binding affinity and interactions between the enzymes and the crosslinkers were analyzed and it was found that chitosan has the lowest binding affinity (-7.9 kcal/mol) and the highest number of interactions. This is followed by DAS, ethylene glycol and glutaraldehyde. By using computational analysis, suitable crosslinker for IsPETase could be determine and this would a cost-effective practice in enzyme immobilization strategy.
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Liu, Xuan, James Sievert, Mary Lu Arpaia und Monica A. Madore. „Postulated Physiological Roles of the Seven-carbon Sugars, Mannoheptulose, and Perseitol in Avocado“. Journal of the American Society for Horticultural Science 127, Nr. 1 (Januar 2002): 108–14. http://dx.doi.org/10.21273/jashs.127.1.108.
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Avocado (Persea americana Mill.) tissues contain high levels of the seven-carbon (C7) ketosugar mannoheptulose and its polyol form, perseitol. Radiolabeling of intact leaves of `Hass' avocado on `Duke 7' rootstock indicated that both perseitol and mannoheptulose are not only primary products of photosynthetic CO2 fixation but are also exported in the phloem. In cell-free extracts from mature source leaves, formation of the C7 backbone occurred by condensation of a three-carbon metabolite (dihydroxyacetone-P) with a four-carbon metabolite (erythrose-4-P) to form sedoheptulose-1,7-bis-P, followed by isomerization to a phosphorylated d-mannoheptulose derivative. A transketolase reaction was also observed which converted five-carbon metabolites (ribose-5-P and xylulose-5-P) to form the C7 metabolite, sedoheptulose-7-P, but this compound was not metabolized further to mannoheptulose. This suggests that C7 sugars are formed from the Calvin Cycle, not oxidative pentose phosphate pathway, reactions in avocado leaves. In avocado fruit, C7 sugars were present in substantial quantities and the normal ripening processes (fruit softening, ethylene production, and climacteric respiration rise), which occurs several days after the fruit is picked, did not occur until levels of C7 sugars dropped below an apparent threshold concentration of ≈20 mg·g-1 fresh weight. The effect of picking could be mimicked by girdling the fruit stalks, which resulted in ripening on the tree. Again, ripening followed a decline in C7 sugars to below an apparent threshold level. Taken together, these data indicate that the C7 sugars play important roles in carbon allocation processes in the avocado tree, including a possible novel role as phloem-mobile ripening inhibitors.
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Zhang, Lei, Chunjiang Liu, Yang Jia, Yidan Mu, Yao Yan und Pengcheng Huang. „Pyrolytic Modification of Heavy Coal Tar by Multi-Polymer Blending: Preparation of Ordered Carbonaceous Mesophase“. Polymers 16, Nr. 1 (04.01.2024): 161. http://dx.doi.org/10.3390/polym16010161.
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In order to achieve the high-value utilization of heavy tar for the production of enhanced-performance graphite foam carbon, the carbon mesophase was ready from the heavy component of low-temperature coal tar, and the coal tar was modified by styrene-butadiene-styrene (SBS), polyethylene (PE) and ethylene-vinyl-acetate (EVA) copolymers. The order degree of the carbonite mesophase was analyzed using a polarizing microscope test, Fourier transform infrared spectroscopy and X-ray diffraction to screen out the most suitable copolymer type and addition amount. Furthermore, the mechanism of modification by this copolymer was analyzed. The results showed that adding SBS, PE and EVA to coal tar would affect the order of carbonaceous mesophase; however, at an addition rate of 10.0 wt.%, the linear-structure SBS copolymer with a styrene/butadiene ratio (S/B) of 30/70 exhibited the optimal degree of ordering in the carbonaceous mesophase. Its foam carbon prepared by polymer modification is the only one that forms a graphitized structure, with d002 of 0.3430 nm, and the maximum values of Lc and La are 3.54 nm and 2.22 nm, respectively. This is because, under elevated pressure and high-temperature conditions, SBS underwent chain scission, releasing a more significant number of methyl and other free radicals that interacted with the coal tar constituents. As a result, it reduced the affinity density of heavy coal tar molecules, enhanced fluidity, promoted the stacking of condensed aromatic hydrocarbons and increased the content of soluble carbonaceous mesophase, ultimately leading to a more favorable alignment of the carbonaceous mesophase.
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Benish, Sarah E., Hao He, Xinrong Ren, Sandra J. Roberts, Ross J. Salawitch, Zhanqing Li, Fei Wang et al. „Measurement report: Aircraft observations of ozone, nitrogen oxides, and volatile organic compounds over Hebei Province, China“. Atmospheric Chemistry and Physics 20, Nr. 23 (30.11.2020): 14523–45. http://dx.doi.org/10.5194/acp-20-14523-2020.
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Abstract. To provide insight into the planetary boundary layer (PBL) production of ozone (O3) over the North China Plain, the Air chemistry Research in Asia (ARIAs) campaign conducted aircraft measurements of air pollutants over Hebei Province, China, between May and June 2016. We evaluate vertical profiles of trace gas species including O3, nitrogen oxides (NOx), carbon monoxide (CO), and volatile organic compounds (VOCs) and relate to rates of O3 production. This analysis shows measured O3 levels ranged from 45 to 146 ppbv, with the peak median concentration (∼ 92 ppbv) occurring between 1000 and 1500 m. The NOx concentrations exhibited strong spatial and altitudinal variations, with a maximum of 53 ppbv. Ratios of CO∕CO2 indicate the prevalence of low-efficiency combustion from biomass burning and residential coal burning but indicate some success of regional pollution controls compared to earlier studies in China. Concentrations of total measured VOCs reveal alkanes dominate the total measured volume mixing ratio of VOCs (68 %), and sources include vehicular emissions, fuel and solvent evaporation, and biomass burning. Alkanes and alkenes/alkynes are responsible for 74 % of the total VOC reactivity assessed by calculating the OH loss rates, while aromatics contribute the most to the total ozone formation potential (OFP) (43 %) with toluene, m/p-xylene, ethylene, propylene, and i-pentane playing significant roles in the aloft production of O3 in this region. In the PBL below 500 m, box model calculations constrained by measured precursors indicate the peak rate of mean O3 production was ∼ 7 ppbv h−1. Pollution frequently extended above the PBL into the lower free troposphere around 3000 m, where NO2 mixing ratios (∼ 400 pptv) led to net production rates of O3 up to ∼ 3 ppbv h−1; this pollution can travel substantial distances downwind. The O3 sensitivity regime is determined to be NOx-limited throughout the PBL, whereas it is more VOC-limited at low altitudes near urban centers, demonstrating that control of both VOCs and NOx is needed to reduce aloft O3 pollution over Hebei.
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Guzmán, Hilmar, Daniela Roldán, Micaela Castellino und Simelys Hernández. „Metal-Oxide-Based Materials for the Sustainable and Tunable Electrochemical CO2 Conversion to Chemicals and Fuels at Industrial Scale“. ECS Meeting Abstracts MA2023-01, Nr. 26 (28.08.2023): 1706. http://dx.doi.org/10.1149/ma2023-01261706mtgabs.
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Anthropogenic activities have impacted the planet’s carbon cycle through the emissions of large amounts of greenhouse gases (GHGs), shifting the equilibrium of human history since the industrial revolution. CO2 is the key contributor to global climate change in the atmosphere. For this reason, the synthesis of high-added-value products CO2 conversion is a promising approach to mitigate climate change.1 Among the different alternatives, exploiting CO2 via electrochemical reduction under mild conditions (ambient pressure and temperature) represents an opportunity to support a low-carbon economy.2 The electrocatalytic (EC) CO2 reduction (CO2R) driven by renewable energy can be exploited for the future energy transition, for the carbon storage into valuable products like syngas (H2/CO mixtures), organic acids (formic acid) and chemicals/fuels (C1+ alcohols).3 A big challenge for the industrialisation of this technology is to find low-cost electrocatalysts, efficient reactors and process conditions. In the efforts to develop efficient, selective and stable materials, we have exploited the current knowledge of thermocatalytic CO2 hydrogenation to develop noble-metal-free CO2R electrocatalysts.4 For instance, Cu/Zn/Al synthesised catalyst producing methanol and CO from the CO2 thermocatalytic (TC) hydrogenation (at H2 pressure (P) of 30 bar and temperature (T) > 200 oC) promotes the formation of methanol (⁓32% of FE) during the EC CO2R in a gas-diffusion-electrode system; while operating in the liquid phase, the same catalyst produces syngas with a tunable composition (95% of FE at the most positive applied potential) and other liquid C2+ products (in both cases at ambient T, P).4 On the other hand, Cu/ZnO electrocatalyst also has been tested at industrially relevant current densities in liquid phase configuration.5 We demonstrated through ex-situ characterisations that the presence of ZnO nanoparticles in the mixed Cu/ZnO catalyst plays an important role in forming and stabilising mixed oxidation states of copper and Cu1+/Cu0 interfaces in the electrocatalyst (in bulk and surface). These interfaces seem to promote CO dimerisation to ethanol. Indeed, ethanol was produced with the Cu/ZnO catalyst, reaching ethanol productivity of about 5.3 mmol∙gcat -1∙h-1 in a liquid-phase configuration at ambient conditions. A Cu/ZnO electrocatalyst also has been tested in a catholyte-free configuration with an increased selectivity to ethylene, reaching approximately 70% of FE, demonstrating that the reaction pathways for EC CO2R are largely determined by transport limitations rather than only by the intrinsic properties of the electrocatalysts. Our results open a promising path for the prospective implementation of metal-oxide nanostructures for CO2 conversion to the chemicals and fuels of the future. Acknowledgements This work has received financial support by the EU H2020 Project SunCOChem (grant agreement: 862192). References Guzmán, H., Russo, N. & Hernández, S. CO2 valorisation towards alcohols by Cu-based electrocatalysts: challenges and perspectives. Green Chem. 23, 1896–1920 (2021). Romero Cuellar, N. S., Wiesner-Fleischer, K., Fleischer, M., Rucki, A. & Hinrichsen, O. Advantages of CO over CO2 as reactant for electrochemical reduction to ethylene, ethanol and n-propanol on gas diffusion electrodes at high current densities. Electrochim. Acta 307, 164–175 (2019). Guzmán, H., Farkhondehfal, M. A., Rodulfo Tolod, K., Russo, N. & Hernández, S. Photo/electrocatalytic hydrogen exploitation for CO2 reduction toward solar fuels production. in Solar Hydrogen Production Processes, Systems and Technologies 560 (Elsevier Inc., 2019). doi:10.1016/C2017-0-02289-9. Guzmán, H. et al. How to make sustainable CO2 conversion to Methanol: Thermocatalytic versus electrocatalytic technology. Chem. Eng. J. 417, 127973 (2021). Guzmán, H. et al. CO2 Conversion to Alcohols over Cu/ZnO Catalysts: Prospective Synergies between Electrocatalytic and Thermocatalytic Routes. ACS Appl. Mater. Interfaces 14, 517−530 (2022).
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Hoffmann, Hendrik, Maximilian Kutter und Christina Roth. „Ag-Based Gas Diffusion Electrodes for the Electrochemical CO2 Reduction by Pulsed Hydrogen Bubble Templation“. ECS Meeting Abstracts MA2023-01, Nr. 26 (28.08.2023): 1700. http://dx.doi.org/10.1149/ma2023-01261700mtgabs.
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Energy-conversion technologies like the electrocatalytic nitrogen reduction reaction (N2RR), carbon monoxide reduction reaction (CORR) and in particular the electrochemical carbon dioxide reduction reaction (CO2RR) can contribute decisively to overcome the challenge of reducing greenhouse gas emissions. By reducing CO2 electrochemically, the carbon-cycle can be closed and industrially desired chemicals like syngas (CO + H2), formic and acetic acid, or hydrocarbons, such as methanol and ethylene, can be produced fossil-fuel free, depending on the catalyst material applied. Ag-based catalysts are very promising in the field of CO2RR, since they show high selectivities towards the reduction of CO2 to CO and current efficiencies of up to 100 %. In aqueous-fed systems, a significant drawback is the limited CO2 solubility, resulting in long diffusion pathways of CO2 within the bulk electrolyte 1, 2. Consequently, industrial conditions cannot be reached for CO2 electrolysis in aqueous solution in H-cell configurations due to the CO2 depletion within the porous electrodes that limit lab scale testing of CO2RR to current densities of approx. 35 mAcm-². One way to achieve commercially relevant current densities (> 200 mAcm-²) is the utilization of gas diffusion electrodes (GDEs) in flow cell configuration. These enable a decrease in CO2 diffusion lengths to approx. 50 nm, enhancing the mass transport to the catalyst 3. In our contribution, we will demonstrate a facile and fast production process of Ag-based GDEs by combining pulsed electrochemical deposition of the Ag catalyst with ionomer infiltration of the electrode. Using the dynamic hydrogen bubble templation method (DHBT), we utilized the parasitic hydrogen evolution reaction (HER) to aid in a solvent free structuring of the 3D catalyst network. In this work, we focused on the deposition parameters by varying different pulse-to-pause ratios in order to increase the amount of deposited catalyst and thus, successfully reduced the overpotential during CO2RR operation (Fig. 1, left). To inhibit electrode flooding and decrease CO2 mass transport limitations during CO2RR, we infiltrated the electrode with a perfluorinated ionomer. SEM and EDS analyses showed a uniform Ag/F distribution along the cross section of the electrodes (Fig. 1, right), which resulted in the conversion of CO2 to CO at industrially viable current densities. References S. Hernandez-Aldave and E. Andreoli, Catalysts, 10(6), 713 (2020). Z. Sun, T. Ma, H. Tao, Q. Fan and B. Han, Chem, 3(4), 560–587 (2017). T. Burdyny and W. A. Smith, Energy Environ. Sci., 12(5), 1442–1453 (2019). Figure 1
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Sugiyama, Masakazu, Shingi Yamaguchi, Hiroji Ebe, Hiromu Kumagai und Tsutomu Minegishi. „(Invited) Electrochemical CO2 Reduction to Chemical Feedstocks: System Capacity and Specifications for Carbon Neutrality“. ECS Meeting Abstracts MA2023-02, Nr. 47 (22.12.2023): 2359. http://dx.doi.org/10.1149/ma2023-02472359mtgabs.
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The transition of an energy system that realizes net-zero CO2 emission requires both energy saving and electrification of energy demands, coupled with the use of CO2-free fuel such as hydrogen and synthetic hydrocarbons derived from captured CO2. In addition, carbon feedstocks for chemical products must originate from biomass, recycled plastics, and captured carbon from both factory effluent and air. In this regard, the electrochemical reduction of CO2 to chemical feedstocks is a promising and indispensable technology for the realization of carbon neutrality. To secure the social implementation of this technology, it is important to quantify the amount of CO2 that needs to be processed by a back-casting approach from an entire picture of a carbon-neutral energy system. Furthermore, the electricity input for CO2 reduction must be counted in reference to the total electricity demand of the energy system. The improvement in the energy efficiency of CO2 reduction is of crucial importance because the large amount of CO2 that needs to be processed may require electricity that exceeds the total electricity demand for direct use. When the CO2 footprint on electricity is not zero, the intensive use of electricity for CO2 reduction will result in the system with positive CO2 emission: the amount of CO2 converted into chemical feedstocks will be smaller than the emitted CO2 upon the generation of electricity which is necessary for electrochemical reduction. Therefore, it is significant to think about the role of electrochemical CO2 reduction from the viewpoint of the energy transition scenario towards net-zero CO2 emission and to analyze the process in terms of life-cycle assessment (LCA). In this presentation, we will focus on the net-zero energy scenario in Japan as an example and will quantify the amount of CO2 that needs to be either sequestered or, more hopefully, converted to chemical feedstocks. Our scenario analysis indicates that the electricity demand in Japan that realizes net-zero CO2 emission will be ca. 1500 TWh, which is ca. 1.5 times larger than the existing value due to the electrification of the existing fossil fuel usage. The amount of CO2 emission will be 84 million tons, which is ca. 8 % of the existing value. As an ideal case, the total amount, 84 million tons of CO2, is assumed to be converted to ethylene by electrochemical reduction rather than being sequestered into the ground. Then, ca. 700 TWh of electricity is required in addition to the electricity demand for direct use, 1500 TWh. The electricity demand for CO2 electrochemical reduction depends on system specifications. Here, the operation voltage of 3 V is assumed. The LCA of a CO2 electrochemical reduction system clarifies the specifications for negative CO2 emission from the system, which is a prerequisite of CO2 recycling. The life-cycle CO2 emission is dependent on the system configuration, and we found that CO2 recycling from a CO2 electrolysis reactor is of crucial importance for the realization of negative CO2 emission. With such a configuration, the most impactful factors on the CO2 balance (fixation versus emission) are the operation voltage and the Faradaic efficiency of CO2 reduction. For negative CO2 emission, they must be below 4 V and above 50%, respectively, assuming the CO2 footprint of electricity as 32 g/kWh corresponding to the existing level for renewable electricity. For 1.5 tons of CO2 fixation upon 1 ton of ethylene production, they must be below 3 V and above 80%, respectively. This analysis highlights the importance of setting targets for research and development from the viewpoint of LCA.
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Guzman, Hilmar, Daniela Roldán, Jonathan Albo, Angel Irabien, Micaela Castellino und Simelys Hernandez. „Sustainable and Tunable Electrochemical CO2 Conversion to Chemicals and Fuels at Industrial Scale Using Metal-Oxide-Based Materials“. ECS Meeting Abstracts MA2024-01, Nr. 37 (09.08.2024): 2166. http://dx.doi.org/10.1149/ma2024-01372166mtgabs.
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The most challenging deal we face these years is the need to lower greenhouse gas (GHG) emissions and tackle climate change; though calls to reduce it are growing louder yearly, emissions remain high. CO2 is the key contributor. For this reason, the synthesis of high-added-value products from CO2 conversion is a promising approach to mitigate the problem.1 Among the different alternatives, exploiting CO2 via electrochemical reduction under mild conditions (ambient pressure and temperature) represents an opportunity to support a low-carbon economy.2 The electrocatalytic (EC) CO2 reduction (CO2R) driven by renewable energy can be exploited for the future energy transition, for the carbon storage into valuable products like syngas (H2/CO mixtures), organic acids (formic acid) and chemicals/fuels (C1+ alcohols).3 A big challenge for the industrialisation of this technology is to find low-cost electrocatalysts, efficient reactors and process conditions. In the efforts to develop efficient, selective and stable materials, we have exploited the current knowledge of thermocatalytic CO2 hydrogenation to develop noble-metal-free CO2R electrocatalysts.4 For instance, Cu/Zn/Al synthesised catalyst producing methanol and CO from the CO2 thermocatalytic (TC) hydrogenation (at H2 pressure (P) of 30 bar and temperature (T) > 200 oC) promotes the formation of methanol (⁓32% of FE) during the EC CO2R in a gas-diffusion-electrode system; while operating in the liquid phase, the same catalyst produces syngas with a tunable composition (95% of FE at the most positive applied potential) and other liquid C2+ products (in both cases at ambient T, P).4 On the other hand, Cu/ZnO electrocatalyst has also been tested at industrially relevant current densities in liquid phase configuration.5 We demonstrated through ex-situ characterisations that the presence of ZnO nanoparticles in the mixed Cu/ZnO catalyst plays an important role in forming and stabilising mixed oxidation states of copper and Cu1+/Cu0 interfaces in the electrocatalyst (in bulk and surface). These interfaces seem to promote CO dimerisation to ethanol. Indeed, ethanol was produced with the Cu/ZnO catalyst, reaching ethanol productivity of about 5.3 mmol∙gcat -1∙h-1 in a liquid-phase configuration at ambient conditions. The Cu/Zn/Al and Cu/ZnO electrocatalysts also have been tested in a catholyte-free configuration with an increased selectivity to ethylene, reaching approx. 60% and 70% of FE, respectively. Here, Cu catalyst structure transformed, on average, completely to metallic with a very thin layer of Cu1+ during testing, which seems to promote the selectivity towards C2H4, demonstrating that the reaction pathways for EC CO2R are largely determined by transport limitations rather than only by the intrinsic properties of the electrocatalysts. Our results open a promising path for the prospective implementation of metal-oxide nanostructures for CO2 conversion to the chemicals and fuels of the future. Acknowledgements This work has received financial support by the EU H2020 SunCOChem Project, grant agreement: 862192. References Guzmán, H., Russo, N. & Hernández, S. CO2 valorisation towards alcohols by Cu-based electrocatalysts: challenges and perspectives. Green Chem. 23, 1896–1920 (2021). Romero Cuellar, N. S., Wiesner-Fleischer, K., Fleischer, M., Rucki, A. & Hinrichsen, O. Advantages of CO over CO2 as reactant for electrochemical reduction to ethylene, ethanol and n-propanol on gas diffusion electrodes at high current densities. Electrochim. Acta 307, 164–175 (2019). Guzmán, H., Farkhondehfal, M. A., Rodulfo Tolod, K., Russo, N. & Hernández, S. Photo/electrocatalytic hydrogen exploitation for CO2 reduction toward solar fuels production. in Solar Hydrogen Production Processes, Systems and Technologies 560 (Elsevier Inc., 2019). doi:10.1016/C2017-0-02289-9. Guzmán, H. et al. How to make sustainable CO2 conversion to Methanol: Thermocatalytic versus electrocatalytic technology. Chem. Eng. J. 417, 127973 (2021). Guzmán, H. et al. CO2 Conversion to Alcohols over Cu/ZnO Catalysts: Prospective Synergies between Electrocatalytic and Thermocatalytic Routes. ACS Appl. Mater. Interfaces 14, 517−530 (2022).
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Nawaz, Gul, Babar Usman, Haowen Peng, Neng Zhao, Ruizhi Yuan, Yaoguang Liu und Rongbai Li. „Knockout of Pi21 by CRISPR/Cas9 and iTRAQ-Based Proteomic Analysis of Mutants Revealed New Insights into M. oryzae Resistance in Elite Rice Line“. Genes 11, Nr. 7 (02.07.2020): 735. http://dx.doi.org/10.3390/genes11070735.
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Rice blast (Magnaporthe oryzae) is a devastating disease affecting rice production globally. The development of cultivars with host resistance has been proved to be the best strategy for disease management. Several rice-resistance genes (R) have been recognized which induce resistance to blast in rice but R gene-mediated mechanisms resulting in defense response still need to be elucidated. Here, mutant lines generated through CRISPR/Cas9 based targeted mutagenesis to investigate the role of Pi21 against blast resistance and 17 mutant plants were obtained in T0 generation with the mutation rate of 66% including 26% bi-allelic, 22% homozygous, 12% heterozygous, and 3% chimeric and 17 T-DNA-free lines in T1 generation. The homozygous mutant lines revealed enhanced resistance to blast without affecting the major agronomic traits. Furthermore, comparative proteome profiling was adopted to study the succeeding proteomic regulations, using iTRAQ-based proteomic analysis. We identified 372 DEPs, among them 149 up and 223 were down-regulated, respectively. GO analysis revealed that the proteins related to response to stimulus, photosynthesis, carbohydrate metabolic process, and small molecule metabolic process were up-regulated. The most of DEPs were involved in metabolic, ribosomal, secondary metabolites biosynthesis, and carbon metabolism pathways. 40S ribosomal protein S15 (P31674), 50S ribosomal protein L4, L5, L6 (Q10NM5, Q9ZST0, Q10L93), 30S ribosomal protein S5, S9 (Q6YU81, Q850W6, Q9XJ28), and succinate dehydrogenase (Q9S827) were hub-proteins. The expression level of genes related to defense mechanism, involved in signaling pathways of jasmonic acid (JA), salicylic acid (SA), and ethylene metabolisms were up-regulated in mutant line after the inoculation of the physiological races of M. oryzae as compared to WT. Our results revealed the fundamental value of genome editing and expand knowledge about fungal infection avoidance in rice.
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AIB, Ekejiuba. „Synergy of the Conventional Crude Oil and the FT-GTL Processes for Sustainable Synfuels Production: The Game Changer Approach-Phase One Category“. Petroleum & Petrochemical Engineering Journal 7, Nr. 1 (11.01.2023): 1–30. http://dx.doi.org/10.23880/ppej-16000330.
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Petroleum was used in its raw state for various purposes in different parts of the world before the discovery of the overwhelming uses of the refined products following the first distillation of lamp oil/ illuminating fuel (kerosene age, 1859-1900) and the development of the internal combustion engines using gasoline or diesel (for vehicles, trucks and ships), the rise in commercial aviation (airplanes and rockets) and other devices, near the beginning of the twentieth century. The burning/combustion of petroleum fuels release greenhouse gases, mainly carbon dioxide (CO2), which creates environmental problems such as global warming, acid rain from sulfur and nitrogen oxide emissions. This rise in CO2 / temperature “global warming” in turn causes other environmental problems such as flooding of coastlines due to melting of the glaciers (polar ice cap melting); disrupted weather patterns i.e. change in wind and rainfall patterns as well as soil moisture; etc., hence the strong quest for an alternative source. On the other hand, apart from serving the aforementioned traditional purposes (transportation fuels), the other petroleum refined products are now the chief source of raw materials (primary petrochemicals such as methanol, ethylene, propylene, butadiene, benzene, toluene and xylene) for the manufacture of chemicals especially organic chemicals, such as textiles, artificial fibers, and plastics of all descriptions, rubber, nitrogen fertilizers, dyestuffs, detergents, pharmaceuticals, medicines, furniture, appliances, solar panels, PVC pipes, bulletproof vests, consumer electronics, wind turbines and automobile parts. Simply put, the use of fossil petroleum refined products goes beyond transportation fuels; it is virtually everything to mankind development. In contrast, synthetic liquid fuels (Synfuels) are liquid fuels (such as gasoline, kerosene, diesel, et cetera) which are produced from substitute/synthetic natural gas (S.N.G.) otherwise known as syngas {derived from virtually any hydrocarbon feedstock, by reaction with steam or oxygen or by reforming of natural gas i.e. methane} and application of the FT-GTL process technique. The appeal of these liquid products (from the FT-GTL process technique) is that they are free from sulfur, aromatics, metals and out performs crude oil petroleum refined products, for instance the diesel will have a very high Octane number and can be a premium blending product while the naphtha would be low in Octane and represents a good petrochemical feedstock. In general, the most significant breakthrough is in syngas for other chemical processes and industries (it is the building block for many petrochemicals, i.e. methanol, ammonia or urea etc.).The theoretical background and basic concepts of the synergy of the existing petroleum crude oil refining technique and the FT-GTL process technique is presented in sufficient detail to tackle the global dual energy challenges (i.e. energy security Petroleum & Petrochemical Engineering Journal 2 Ekejiuba AIB. Synergy of the Conventional Crude Oil and the FT-GTL Processes for Sustainable Synfuels Production: The Game Changer Approach-Phase One Category. Pet Petro Chem Eng J 2023, 7(1): 000330. Copyright© Ekejiuba AIB. and climate change goals) or more broadly the challenge to produce more of the affordable energy that society needs and the challenge to produce energy that’s less carbon intensive (i.e. carbon neutral-zero carbon dioxide emissions). Operationally, the overall products from the crude oil petroleum refining operation is reformed to syngas (CO + H2 mixture) “synthesis gas or synthetic gas” via steam reforming or dry reforming or bi-reforming and subsequently converted to Synfuel “Synthetic liquid fuels” using the FT-GTL Fischer-Tropsch (FT) Technology a.k.a. FT-GTL synthesis process. The super heated steam (H2O), CO2 and waste heat produced during the FT- process is used directly in a chemical reactor to further generate CO/H2 mixture instead of embarking on carbon capture (for CO production) and water electrolysis (for H2 production). The high purity oxygen (O2) and heat produced in the chemical reactor is also directly used in the partial oxidation (POX) or autothermal reforming (ATR), units for additional production of CO/H2 mixture. Furthermore fraction of the CO2 and steam/ H2O generated in the FT process unit can be used for dry reforming or bi-reforming of a fraction of the conventional crude oil refinery products into syngas (CO + H2 mixture). Ultimately, this synergy of refining technique will help refiners to meet new guidelines for very low sulfur fuels and general environmental standards as well as enable the continued use of the fossil petroleum energy resources to help the growing demand in energy and worldwide concern towards alternatives to the use of fossil fuel for energy production. This means that, the world will never stop using fossil energy resource. That is no transition/phase out of crude oil and natural gas, rather there will be transition away from emissions i.e. producing these products in a way that has lower and lower emissions. Even the enthusiast of zero emission vehicles will need roads to drive the cars, which means that we need to produce bitumen. Similarly, the enthusiast for alternative electricity via wind turbines and solar panel (photovoltaic and thermal, PV/T collectors) will need lubricants for the gearboxes and generators mounted inside the turbines and various petrochemical products to fabricate panels and inverters, as well as their installation and connection cables, batteries, and other gadgets. Thus, if we can produce bitumen, lubricants and other petrochemicals with lower and lower emission it will be a win situation for everybody. Win for the environment, win for the economy, and win for the affordability and a win for the environmentalist.
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Liu, Han, Simon Laflamme und Matthias Kollosche. „Paintable Silicone-Based Corrugated Soft Elastomeric Capacitor for Area Strain Sensing“. Sensors 23, Nr. 13 (04.07.2023): 6146. http://dx.doi.org/10.3390/s23136146.
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Recent advances in soft polymer materials have enabled the design of soft machines and devices at multiple scales. Their intrinsic compliance and robust mechanical properties and the potential for a rapid scaling of the production process make them ideal candidates for flexible and stretchable electronics and sensors. Large-area electronics (LAE) made from soft polymer materials that are capable of sustaining large deformations and covering large surfaces and are applicable to complex and irregular surfaces and transducing deformations into readable signals have been explored for structural health monitoring (SHM) applications. The authors have previously proposed and developed an LAE consisting of a corrugated soft elastomeric capacitor (cSEC). The corrugation is used to engineer the directional strain sensitivity by using a thermoplastic styrene-ethylene-butadiene-styrene (SEBS). A key limitation of the SEBS-cSEC technology is the need of an epoxy for reliable bonding of the sensor onto the monitored surface, mainly attributable to the sensor’s fabrication process that comprises a solvent that limits its direct deployment through a painting process. Here, with the objective to produce a paintable cSEC, we study an improved solvent-free fabrication method by using a commercial room-temperature-vulcanizing silicone as the host matrix. The matrix is filled with titania particles to form the dielectric layer, yielding a permittivity of 4.05. Carbon black powder is brushed onto the dielectric and encapsulated with the same silicone to form the conductive stretchable electrodes. The sensor is deployed by directly painting a layer of the silicone onto the monitored surface and then depositing the parallel plate capacitor. The electromechanical behavior of the painted silicone-cSEC was characterized and exhibited good linearity, with an R2 value of 0.9901, a gauge factor of 1.58, and a resolution of 70 με. This resolution compared well with that of the epoxied SEBS-cSEC reported in previous work (25 με). Its performance was compared against that of its more mature version, the SEBS-cSEC, in a network configuration on a cantilever plate subjected to a step-deformation and to free vibrations. Results showed that the performance of the painted silicone-sCEC compared well with that of the SEBS-cSEC, but that the use of a silicone paint instead of an epoxy could be responsible for larger noise and the under-estimation of the dominating frequency by 6.7%, likely attributable to slippage.
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Mousavizadeh Mojarad, Fatemeh Sadat, Manila OV, Cody Carr, Jialang Li, Warren Edward Piers und Viola Ingrid Birss. „Re(bipyridine)-Polypyrrole Monolayer Deposition on Nanoporous Carbon Scaffolds for Electrochemical CO2 Reduction“. ECS Meeting Abstracts MA2023-02, Nr. 54 (22.12.2023): 2609. http://dx.doi.org/10.1149/ma2023-02542609mtgabs.
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The CO2 concentration in the atmosphere has increased from 280 ppm in 1750 to nearly 420 ppm in 2022, leading to multiple environmental issues. Thus, developing an efficient approach for the conversion and use of CO2 is one of our most pressing objectives today. Among different strategies to remove CO2, the electrochemical conversion of CO2 to carbon-based fuels is actively being pursued by many researchers. However, CO2 is thermodynamically quite stable (the dissociation energy of a C=O bond is approximately 750 kJ mol-1) and thus the activation of the bonds in CO2 requires a considerable overpotential, especially when carried out at low temperatures in aqueous solutions, resulting in low efficiency. Although a range of gaseous and liquid products, including formic acid, carbon monoxide, methane, ethylene, and ethanol, can be produced by transferring multiple protons and electrons, the formation of CO is simpler and more straightforward for industrial adoption. In this process, renewable energy would be used to operate the CO2 electrolyzer to convert CO2 to CO, which can then be utilized as a chemical feedstock to produce a variety of fuels [1]. Molecular catalysts have been widely studied for CO2 reduction, with research on the development of solid hybrid systems that comprise an immobilized catalyst on a support well underway. This method offers further advantages, as it can further facilitate catalyst recyclability and product separation. Carbon-based materials are the most extensively employed supports discussed in the literature, due to their low cost, high electrical conductivity, and flexibility. [Re(2,2′-bipyridine)(CO)3Cl] ([Re(bpy)]), commonly known as Lehn's catalyst, is among the most extensively studied molecular electrocatalysts for the selective CO2 reduction to CO. While various studies have focused on its optimization, showing excellent performance in organic solutions, CO2 reduction should ultimately be accomplished in aqueous media. Despite the fact that hybrid systems eliminate the requirement for aqueous solubility of the catalyst, examples of immobilized [Re(bpy)] for the stable and effective CO2-to-CO conversion in water remain uncommon. In our previous work, the [Re(4-(4-aminophenethyl)-4′-methyl-2,2′-bipyridine)(CO)3Cl] ([Re-(NH2-bpy)]) complex was synthesized and covalently anchored to a colloid-imprinted carbon (CIC) powder by the oxidation of its amino group. The CICs have a large surface area, homogeneous and controllable pore sizes, and ultra-low tortuosity. While the Re/CIC catalyst converted CO2 to CO with a high selectivity of 93% and a Re-based TON of around 900, its stability was poor and the coverage of the CIC by the Re catalyst was quite low [2]. In later work, catalyst anchoring on the CIC surface was achieved by electrochemical polymerization of the pyrrole group attached to the complex, producing uniform films that exhibited Faradaic efficiencies from 90-100% as well as very good long-term stability under catalytic conditions, producing CO with a selectivity of over 70% for at least 24 hours [3]. Herein, we report a similar [Re(bpy)] hybrid electrode constructed by covalent surface tethering of the Re catalyst via pyrrole polymerization but using a self-supported nanoporous carbon scaffold. The advantages of adopting the NCS as opposed to powdered supports include the lack of needed binder, which can cover active sites, the ease of imaging the catalyst before and after testing, and the ability to carry out flow through experiments to overcome mass transport issues and also local pH effects. The CO2RR tests were performed in an H-cell using a KHCO3 solution saturated with CO2, while the catalyst was loaded onto the NCS either by immersing the NCS in a 5 mM Re solution followed by electrodeposition in a Re-free solution (Method A), or by electrodeposition at slow sweep rates in the Re-containing solution (Method B). The bare NCS was studied first, showing the exclusive production of hydrogen, similar to the CIC powders, whereas our hybrid electrode generated 100% CO between -0.4 and -0.7 V vs. RHE. Method A showed that the number of immersion steps used for Re deposition correlated with the coverage of the NCS by the catalyst, in turn giving higher selectivity, higher activity, and a significantly higher TOF (0.13 s-1 vs. 0.03 s-1, found with the CICs). This is due to better [Re] utilisation within the NCS pores (more electroactive [Re]) and a better morphology, retaining the open pores after catalyst deposition. However, the durability was compromised at higher CO2RR rates. In comparison, Method B showed similar excellent performance metrics, while also exhibiting better reproducibility for samples prepared identically. References Jin, S., et al., Angewandte Chemie, 2021. 133(38) Willkomm, J., et al., ACS Applied Energy Materials, 2019. 2(4) Willkomm, J., et al., ACS Catalysis, 2021. 11(3)
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Xia, Rong, und Feng Jiao. „Electrosynthesis of Value-Added Chemicals Using Water As a Proton Source“. ECS Meeting Abstracts MA2022-02, Nr. 53 (09.10.2022): 2469. http://dx.doi.org/10.1149/ma2022-02532469mtgabs.
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Electrifying chemical productions is a potential approach to decarbonizing the chemical industry. The electrochemical processes, when powered by renewable electricity, have lower carbon footprints than conventional thermochemical routes. Using water as the proton source avoids the energy-intensive dry-reforming process to produce H2 from fossil fuels, and electrochemical reaction using voltage as driving force instead of elevated pressure enables the reaction to happen at ambient temperature and pressure. Electrosynthesis of value-added ethylamine and ethylene glycol are used as two examples in this presentation. Herein, we report an electrocatalytic route to produce ethylamine selectively through an electroreduction of acetonitrile at ambient temperature and pressure. Among all the electrocatalysts, Cu nanoparticles exhibited the highest ethylamine Faradaic efficiency (FE, ~96%) at -0.29 V versus reversible hydrogen electrode (RHE). In a flow cell configuration, an ethylamine partial current density of 846 mA cm-2 was achieved using the Cu catalyst at -0.73 V vs. RHE in a 1 M NaOH electrolyte containing 12 wt.% acetonitrile. Under a constant current density operation at 100 mA cm-2, the Cu catalyst also showed a stable 20-hour performance in a continuous acetonitrile electroreduction with an 86% ethylamine FE. Moreover, the reaction mechanism of acetonitrile electroreduction was investigated by density functional theory calculations, in which the calculated free energy changes of the rate-limiting steps in acetonitrile reduction and hydrogen evolution reaction suggest a better ethylamine selectivity for Cu than other conventional hydrogenation catalysts (i.e., Ni and Pt).
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Xiao, Yang, Jie Lu, Kean Chen, Yuliang Cao, Chengtao Gong und Fu-Sheng Ke. „Linkage Engineering in Covalent Organic Frameworks for Metal‐Free Electrocatalytic C2H4 Production from CO2“. Angewandte Chemie, 18.04.2024. http://dx.doi.org/10.1002/ange.202404738.
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Electrocatalytic carbon dioxide reduction reaction (CO2RR) to produce ethylene (C2H4) is conducive to sustainable development of energy and environment. At present, most electrocatalysts for C2H4 production are limited to the heavy metal copper, meanwhile, achieving metal‐free catalysis remains a challenge. Noted piperazine with sp3 N hybridization is beneficial to CO2 capture, but CO2RR performance and mechanism have been lacking. Herein, based on linkage engineering, we construct a novel high‐density sp3 N catalytic array via introducing piperazine into the crystalline and microporous aminal‐linked covalent organic frameworks (COFs). Thanks to its high sp3 N density, strong CO2 capture capacity and great hydrophilicity, aminal‐linked COF successfully achieves the conversion of CO2 to C2H4 with a Faraday efficiency up to 19.1%, which is stand out in all reported metal‐free COF electrocatalysts. In addition, a series of imine‐linked COFs are synthesized and combined with DFT calculations to demonstrate the critical role of sp3 N in enhancing the kinetics of CO2RR. Therefore, this work reveals the extraordinary potential of linkage engineering in COFs to break through some catalytic bottlenecks.
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Xiao, Yang, Jie Lu, Kean Chen, Yuliang Cao, Chengtao Gong und Fu-Sheng Ke. „Linkage Engineering in Covalent Organic Frameworks for Metal‐Free Electrocatalytic C2H4 Production from CO2“. Angewandte Chemie International Edition, 18.04.2024. http://dx.doi.org/10.1002/anie.202404738.
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Electrocatalytic carbon dioxide reduction reaction (CO2RR) to produce ethylene (C2H4) is conducive to sustainable development of energy and environment. At present, most electrocatalysts for C2H4 production are limited to the heavy metal copper, meanwhile, achieving metal‐free catalysis remains a challenge. Noted piperazine with sp3 N hybridization is beneficial to CO2 capture, but CO2RR performance and mechanism have been lacking. Herein, based on linkage engineering, we construct a novel high‐density sp3 N catalytic array via introducing piperazine into the crystalline and microporous aminal‐linked covalent organic frameworks (COFs). Thanks to its high sp3 N density, strong CO2 capture capacity and great hydrophilicity, aminal‐linked COF successfully achieves the conversion of CO2 to C2H4 with a Faraday efficiency up to 19.1%, which is stand out in all reported metal‐free COF electrocatalysts. In addition, a series of imine‐linked COFs are synthesized and combined with DFT calculations to demonstrate the critical role of sp3 N in enhancing the kinetics of CO2RR. Therefore, this work reveals the extraordinary potential of linkage engineering in COFs to break through some catalytic bottlenecks.
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Bao, Haihong, Yuan Qiu, Xianyun Peng, Jia-ao Wang, Yuying Mi, Shunzheng Zhao, Xijun Liu et al. „Isolated copper single sites for high-performance electroreduction of carbon monoxide to multicarbon products“. Nature Communications 12, Nr. 1 (11.01.2021). http://dx.doi.org/10.1038/s41467-020-20336-4.
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AbstractElectrochemical carbon monoxide reduction is a promising strategy for the production of value-added multicarbon compounds, albeit yielding diverse products with low selectivities and Faradaic efficiencies. Here, copper single atoms anchored to Ti3C2Tx MXene nanosheets are firstly demonstrated as effective and robust catalysts for electrochemical carbon monoxide reduction, achieving an ultrahigh selectivity of 98% for the formation of multicarbon products. Particularly, it exhibits a high Faradaic efficiency of 71% towards ethylene at −0.7 V versus the reversible hydrogen electrode, superior to the previously reported copper-based catalysts. Besides, it shows a stable activity during the 68-h electrolysis. Theoretical simulations reveal that atomically dispersed Cu–O3 sites favor the C–C coupling of carbon monoxide molecules to generate the key *CO-CHO species, and then induce the decreased free energy barrier of the potential-determining step, thus accounting for the high activity and selectivity of copper single atoms for carbon monoxide reduction.
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Liu, Yue, Ye Tian, Wenqing Cao, Shuaiheng Zhao, Yingqi Qiu und Lin Feng. „Bifunctional Portable Powder for Freshwater Production With Moisture Harvesting and Undrinkable Water Purification“. Small, 22.10.2024. http://dx.doi.org/10.1002/smll.202407681.
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AbstractFreshwater scarcity threatens human survival, particularly in extreme environments like deserts, oceans, and space. Compatible atmospheric water harvesting and undrinkable water purification offer an affordable approach to solving freshwater scarcity in these extreme environments. Nonetheless, developing composite sorbent to attain efficient atmospheric water harvesting and undrinkable water purification remains challenging. Hence, a portable hybrid hygroscopic powder (HLC powder) consisting of hydroxypropyl chitosan, dibenzaldehyde‐functional poly(ethylene glycol), lithium chloride (LiCl), and nano carbon black is proposed. The HLC powder with optimized LiCl load can capture moisture from the air, showing a high water uptake of 1.76 g g−1 at 34% relative humidity (RH) and appropriate over a wide humidity from 34% to 75% RH. pH‐responsive sol‐gel transition induced by Schiff base bonds transforms the HLC solution into hydrogel, inhibiting hydrated salt leakage. Meanwhile, to achieve efficient undrinkable water purification, the LiCl‐free hybrid powder is utilized to convert the undrinkable water, including seawater, dye water, and human urine, to photothermal hydrogel evaporators with low evaporation enthalpies and high evaporation rates ranging from 1.81 to 2.05 kg m−2 h−1 under one sun. This strategy establishes a new path to conveniently obtaining freshwater, breaking hydrological restrictions.
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Akpe, Shedrack G., Sun Hee Choi und Hyung Chul Ham. „Direct C–C bond scission of xylitol to ethylene and propylene glycol precursors using single-atom catalysts (SACs) anchored on MgO“. APL Materials 11, Nr. 5 (01.05.2023). http://dx.doi.org/10.1063/5.0146265.
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Shorter chain alcohols, as opposed to longer ones, are beneficial as biomass feedstock for chemicals and fuels, including hydrogen production. More so, it has been demonstrated that carbon–carbon rather than carbon–oxygen bond-cleaving activity determines the product selectivity of a metal catalyst for higher oxygenates reforming. In this report, we investigate the direct C2–C3 bond-cleaving activity of xylitol via first-principles, periodic density functional theory calculations to identify the differences in activities between single-crystal catalysts (SCCs) and single-atom catalysts (SACs). A comparison of the kinetic barriers revealed that xylitol's C–C bond scission appears to be a near-impossible task on SCCs. However, SACs demonstrated higher performance. For example, Ir1/MgO and Ir1/MgO_Ovac (having surface oxygen vacancy) yielded ∼72% and 54% decrease, respectively, in Gibb’s free activation energy compared to Ir (111) at the xylitol reforming operating temperature of 473 K. Furthermore, electronic structure calculations revealed an up-shift in the DOS for the surface M1 atoms in all investigated SACs compared to the surface atoms of their respective SCCs, resulting in M1 higher d-band center and stronger adsorbate (s) binding. This study highlights the importance of SACs for boosting the atom efficiency of costly metals while also offering a new strategy for tuning the activity of catalytic reactions.
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Mahmod, Abdualfatah S., Abdrabba I. Hassan und Rasha A. Alabd. „Simulation Of Dehydration Process By Using Ethylene Glycol Butyl Ether (Egbe)“. Al-Mukhtar Journal of Engineering Research, 14.05.2024, 01–09. http://dx.doi.org/10.54172/14qx1748.
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The raw natural gas extracted from production wells contains many impurities such as oil, sulphur, carbon dioxide, nitrogen, and other impurities. Among these impurities that must be removed in order to achieve the specifications of the liquid natural gas (LNG) is a water vapor. Because free water causes hydrate formation in transport pipelines and in addition to corrosion when combine with acid gases, resulting in heavy losses in maintenance costs of transport pipelines. For these reasons, natural gas must be dehydrated. The most common methods is Glycol dehydration process, and this process has a good results. In this paper, we have suggested a solvent and simulated it and proof its effectiveness in dissolving the water and dehydration the gas instead of using Tri-ethylene Glycol (TEG). This solvent is Ethylene Glycol Butyl Ether (EGBE), It is used widely as a solvent in surface coatings, and used in metal and household cleaners. It isn’t use in previously natural gas processing. The comparison between glycol types done by Aspen Hysys (glycol package model approach) and according to the dry gas specifications, the simulation results show that: the appropriate flow rate for EG, DEG, TEG, TREG and EGBE are 500 Kgmol/h, 429.5 Kgmol/h, 337.1 Kgmol/h, 80 Kgmol/h and 25.3 Kgmol/h, respectively. Ethylene Glycol Butyl Ether prove a high the efficiency it in dissolving the water with a little flow rate, as well as decrease the energy required for the operation. This paper looks to the use of EGBE as an alternative to TEG for its high efficacy in dissolving water, also significant decrease in the cost of dehydration gas about 98.7 x 109 $/Year].
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„The inhibition performance of mono-ethylene glycol on corrosion rate of x-80 grade carbon steel in saturated brine environment.“ African Journal of Engineering and Environment Research 1, Nr. 1 (22.02.2020). http://dx.doi.org/10.37703/ajoeer.org.ng/q12020/03.
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The formation/deposition of hydrate and scale in gas production and transportation pipeline has continue to be a major challenge in the oil and gas industry. Pipeline transport is one of the most efficient, reliable and safer means of transporting petroleum products from the well sites to either the refineries or to the final destinations. Acetic acid (HAc), is formed in the formation water which also present in oil and gas production and transportation processes. Acetic acid aids corrosion in pipelines and in turn aids the formation and deposition of scales which may eventually choke off flow. Most times, Monethylene Glycol (MEG) is added into the pipeline as an antifreeze and anticorrosion agent. Some laboratory experiments have shown that the MEG needs to be separated from unwanted substance such as HAc that are present in the formation water to avoid critical conditions in the pipeline. Internal pipeline corrosion slows and decreases the production of oil and gas when associated with free water and reacts with CO2 and organic acid by lowering the integrity of the pipe. In this study, the effect of Mono-Ethylene Glycol (MEG) and Acetic acid (HAc) on the corrosion rate of X-80 grade carbon steel in CO2 saturated brine were evaluated at 25oC and 80oC using 3.5% NaCl solution in a semi-circulation flow loop set up. Weight loss and electrochemical measurements using the linear polarization resistance (LPR) and electrochemical impedance spectroscope (EIS) were used in measuring the corrosion rate as a function of HAc and MEG concentrations. The results obtained so far shows an average corrosion rate increases from 0.5 to 1.8 mm/yr at 25oC, and from 1.2 to 3.5 mm/yr at 80oC in the presence of HAc. However, there are decrease in corrosion rate from 1.8 to 0.95 mm/yr and from 3.5 to 1.6mm/yr respectively at 25oC and 80oC on addition of 20% and 80% MEG concentrations to the solution. It is also noted that the charge transfer with the electrochemical measurements (EIS) results is the main corrosion controlling mechanism under the test conditions. The higher temperature led to faster film dissolution and higher corrosion rate in the presence of HAc. The EIS results also indicate that the charge transfer controlled behaviour was as a result of iron carbonate layer accelerated by the addition of different concentrations of MEG to the system. Key words: CO2 corrosion, Carbon steel, MEG, HAc, Inhibition, Environment.
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Zhang, Mingyi, Ye Sun, Xin Chang und Peng Zhang. „Template-Free Synthesis of One-Dimensional g-C3N4 Chain Nanostructures for Efficient Photocatalytic Hydrogen Evolution“. Frontiers in Chemistry 9 (15.03.2021). http://dx.doi.org/10.3389/fchem.2021.652762.
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The development of graphite-carbon nitride (g-C3N4) photocatalyst is of great significance for various visible utilization applications. Control the nanostructures of g-C3N4 can tailor its photocatalytic performance. In this paper, one-dimensional chain-like g-C3N4 was successfully synthesized by heat-induced polymerization of melamine which was saturated in ethylene glycol. The photocatalytic hydrogen production rate (HER) of the prepared g-C3N4 chain enhanced about 3 times than that of bulk g-C3N4, increasing from 9.6 μmolh−1 to 28.7 μmolh−1. The improved photocatalytic activity of the g-C3N4 chain was attributed to the advantages of porosity and nanostructure. The extraordinary nanopores result in an enlarged specific surface area for adsorption and the production of abundantly available channels for charge transfer. The one-dimensional chain-like structure can facilitate the exposure of internal/external active sites as many as possible, and induce the directional migration of charge carriers.