Hasil untuk "Chemical technology"

A. Hauch, R. Küngas, P. Blennow et al.

Electrolysis feels the heat Electricity infrastructure powered by sunlight and wind requires flexible storage capacity to compensate for the intermittency of these sources. In this context, Hauch et al. review progress in solid oxide electrolyzer technology to split water and/or carbon dioxide into chemical fuels. These devices, which rely on oxide conduction between cathode and anode, use nonprecious metals as catalysts and operate above 600°C, thereby benefiting from thermodynamic and kinetic efficiencies. The authors highlight recent optimizations of cell components as well as systems-level architecture. Science, this issue p. eaba6118 BACKGROUND Alleviating the worst effects of climate change requires drastic modification of our energy system: moving from fossil fuels to low-carbon energy sources. The challenge is not the amount of renewable energy available—energy potential from solar and wind exceeds global energy consumption many times over. Rather, the key to a 100% renewable energy supply lies in the integration of the growing share of intermittent sources into a power infrastructure that can meet continuous demand. The higher the share of renewables, the more flexible and interconnected the energy system (the electric grid, the gas and heat networks, etc.) needs to be. Critically, a future energy system where the supply of electricity, heat, and fuels is based solely on renewables relies heavily on technologies capable of converting electricity into chemicals and fuels suitable for heavy transport at high efficiencies. In addition, higher electrolysis efficiency and integrated fuel production can decrease the reliance on bioenergy further than conventional electrolysis can. ADVANCES Electrolysis is the core technology of power-to-X (PtX) solutions, where X can be hydrogen, syngas, or synthetic fuels. When electrolysis is combined with renewable electricity, the production of fuels and chemicals can be decoupled from fossil resources, paving the way for an energy system based on 100% renewable energy. Solid oxide electrolysis cell (SOEC) technology is attractive because of unrivaled conversion efficiencies—a result of favorable thermodynamics and kinetics at higher operating temperatures. SOECs can be used for direct electrochemical conversion of steam (H2O), carbon dioxide (CO2), or both into hydrogen (H2), carbon monoxide (CO), or syngas (H2+CO), respectively. SOECs can be thermally integrated with a range of chemical syntheses, enabling recycling of captured CO2 and H2O into synthetic natural gas or gasoline, methanol, or ammonia, resulting in further efficiency improvements compared with low-temperature electrolysis technologies. SOEC technology has undergone tremendous development and improvements over the past 10 to 15 years. The initial electrochemical performance of state-of-the-art SOEC single cells has more than doubled, while long-term durability has been improved by a factor of ∼100. Similar improvements in performance and durability have been achieved on the stack level. Furthermore, SOEC technology is based on scalable production methods and abundant raw materials such as nickel, zirconia, and steel, not precious metals. Performance and durability improvements as well as increased scale-up efforts have led to a hundredfold gas production capacity increase within the past decade and to commissioning of the first industrially relevant SOEC plants. Over the next 2 to 3 years, plant size is expected to further increase by a factor of almost 20. In recent years, SOEC systems have been integrated with downstream synthesis processes: examples include a demonstration plant for upgrading of biogas to pipeline quality methane and the use of syngas from an SOEC plant to produce fuels for transport via the Fischer-Tropsch process. OUTLOOK Improved understanding of the nanoscale processes occurring in SOECs will continue to result in performance and lifetime gains on the cell, stack, and system levels, which in turn will enable even larger and more efficient SOEC plants. In Germany, the share of intermittent renewables in the electricity supply has passed 30%, while in Denmark, intermittent sources account for almost 50% of the electricity supply. As this happens for a growing number of countries, demand for efficient energy conversion technologies such as SOECs is poised to increase. The increasing scale will help bring down production costs, thereby making SOECs cost-competitive with other electrolysis technologies and, given sufficiently high CO2 emissions taxation, cost-competitive with fossil-based methods for producing H2 and CO. SOECs offer an opportunity to decrease the costs of future renewable energy systems through more efficient conversion and enable further integration of renewables into the energy mix. Solid oxide electrolyzers: From nanoscale to macroscale. The splitting of H2O or CO2 occurs at solid oxide electrolysis cell (SOEC) electrodes. Multiple cells are combined into SOEC stacks, which are in turn combined into SOEC plants. When renewable electricity is used, the production of transport fuels and chemicals can be decoupled from fossil resources. SOECs operate at elevated temperatures, resulting in electrolysis efficiencies unattainable by other electrolysis technologies. In a world powered by intermittent renewable energy, electrolyzers will play a central role in converting electrical energy into chemical energy, thereby decoupling the production of transport fuels and chemicals from today’s fossil resources and decreasing the reliance on bioenergy. Solid oxide electrolysis cells (SOECs) offer two major advantages over alternative electrolysis technologies. First, their high operating temperatures result in favorable thermodynamics and reaction kinetics, enabling unrivaled conversion efficiencies. Second, SOECs can be thermally integrated with downstream chemical syntheses, such as the production of methanol, dimethyl ether, synthetic fuels, or ammonia. SOEC technology has witnessed tremendous improvements during the past 10 to 15 years and is approaching maturity, driven by advances at the cell, stack, and system levels.

Hideaki Kobayashi, A. Hayakawa, K.D. Kunkuma . A. Somarathne et al.

Abstract This paper focuses on the potential use of ammonia as a carbon-free fuel, and covers recent advances in the development of ammonia combustion technology and its underlying chemistry. Fulfilling the COP21 Paris Agreement requires the de-carbonization of energy generation, through utilization of carbon-neutral and overall carbon-free fuels produced from renewable sources. Hydrogen is one of such fuels, which is a potential energy carrier for reducing greenhouse-gas emissions. However, its shipment for long distances and storage for long times present challenges. Ammonia on the other hand, comprises 17.8% of hydrogen by mass and can be produced from renewable hydrogen and nitrogen separated from air. Furthermore, thermal properties of ammonia are similar to those of propane in terms of boiling temperature and condensation pressure, making it attractive as a hydrogen and energy carrier. Ammonia has been produced and utilized for the past 100 years as a fertilizer, chemical raw material, and refrigerant. Ammonia can be used as a fuel but there are several challenges in ammonia combustion, such as low flammability, high NOx emission, and low radiation intensity. Overcoming these challenges requires further research into ammonia flame dynamics and chemistry. This paper discusses recent successful applications of ammonia fuel, in gas turbines, co-fired with pulverize coal, and in industrial furnaces. These applications have been implemented under the Japanese ‘Cross-ministerial Strategic Innovation Promotion Program (SIP): Energy Carriers’. In addition, fundamental aspects of ammonia combustion are discussed including characteristics of laminar premixed flames, counterflow twin-flames, and turbulent premixed flames stabilized by a nozzle burner at high pressure. Furthermore, this paper discusses details of the chemistry of ammonia combustion related to NOx production, processes for reducing NOx, and validation of several ammonia oxidation kinetics models. Finally, LES results for a gas-turbine-like swirl-burner are presented, for the purpose of developing low-NOx single-fuelled ammonia gas turbine combustors.

M. Hayyan, M. Hashim, I. Alnashef

K. Elvira, Xavier Casadevall i Solvas, R. Wootton et al.

G. Centi, E. A. Quadrelli, S. Perathoner

Krishnendu Saha, Sarit S. Agasti, Chaekyu Kim et al.

Rohit Thirumdas, Anjinelyulu Kothakota, U. Annapure et al.

Abstract Background Cold plasma is an emerging non-thermal disinfection and surface modification technology which is chemical free, and eco-friendly. Plasma treatment of water, termed as plasma activated water (PAW), creates an acidic environment which results in changes of the redox potential, conductivity and in the formation of reactive oxygen (ROS) and nitrogen species (RNS). As a result, PAW has different chemical composition than water and can serve as an alternative method for microbial disinfection. Scope and approach This paper reviews the different plasma sources employed for PAW generation, its physico-chemical properties and potential areas of PAW applications. More specifically, the physical and chemical properties of PAW are outlined in relation to the acidity, conductivity, redox potential, and concentration of ROS, RNS in the treated water. All these effects are in microbial nature, so the applications of PAW for microbial disinfection are also summarized in this review. Finally, the role of PAW in improving the agricultural practices, for example, promoting seed germination and plant growth, is also presented. Key findings and conclusions PAW appears to have a synergistic effect on the disinfection of food while it can also promote seedling growth of seeds. The increase in the nitrate and nitrite ions in the PAW could be the main reason for the increase in plant growth. Soaking seeds in PAW not only serves as an anti-bacterial but also enhances the seed germination and plant growth. PAW could potentially be used to increase crop yield and to fight against the drought stress environmental conditions.

S. Crooke, B. Baker, R. Crooke et al.

James J. Lai, Zoe L. Chau, Sheng-You Chen et al.

Exosomes are extracellular vesicles that share components of their parent cells and are attractive in biotechnology and biomedical research as potential disease biomarkers as well as therapeutic agents. Crucial to realizing this potential is the ability to manufacture high‐quality exosomes; however, unlike biologics such as proteins, exosomes lack standardized Good Manufacturing Practices for their processing and characterization. Furthermore, there is a lack of well‐characterized reference exosome materials to aid in selection of methods for exosome isolation, purification, and analysis. This review informs exosome research and technology development by comparing exosome processing and characterization methods and recommending exosome workflows. This review also provides a detailed introduction to exosomes, including their physical and chemical properties, roles in normal biological processes and in disease progression, and summarizes some of the on‐going clinical trials.

E. Lassner, W. Schubert

J. Adánez, A. Abad, T. Mendiara et al.

Abstract Chemical Looping Combustion (CLC) has arisen during last years as a very promising combustion technology for power plants and industrial applications, with inherent CO2 capture which reduces the energy penalty imposed on other competing technologies. The use of solid fuels in CLC has been highly developed in the last decade and currently stands at a technical readiness level (TRL) of 6. In this paper, experience gained during CLC operation in continuous units is reviewed and appraised, focusing mainly on technical and environmental issues relating to the use of solid fuels. Up to now, more than 2700 h of operational experience has been reported in 19 pilot plants ranging from 0.5 kWth to 4 MWth. When designing a CLC unit of solid fuels, the preferred configuration for the scale-up is a two circulating fluidized beds (CFB) system. Coal has been the most commonly used solid fuel in CLC, but biomass has recently emerged as a very promising option to achieve negative emissions using bioenergy with carbon dioxide capture and storage (BECCS). Mostly low cost iron and manganese materials have been used as oxygen carriers in the so called in-situ gasification CLC (iG-CLC). The development of Chemical Looping with Oxygen Uncoupling (CLOU) makes a qualitative step forward in the solid fuel combustion, due to the use of materials able to release oxygen. The performance and environmental issues of CLC of solid fuels is evaluated here. Regarding environmental aspects, the pollutant emissions (SO2, NOx, etc.) released into the atmosphere from the air reactor are no cause of concern for the environment. However, the presence of SO2, NOx and Hg at the exit of the fuel reactor affects CO2 quality, which must be taken into account during the later compression and purification stages. The effect of the main variables affecting CLC performance is evaluated for fuel conversion, CO2 capture rate, and combustion efficiency obtained in different CLC units. Solid fuel conversion is normally not complete during operation, due to the undesired loss of char. A methodology is presented to extrapolate the current information to what could be expected in a larger CLC system. CO2 capture near 100% has been reported using a highly efficient carbon stripper, highly reactive fuels (such as lignites and biomass, etc.) or by the CLOU process. Operational experience in iG-CLC has showed that it is not possible to reach complete fuel combustion, making an additional oxygen polishing step necessary. For the further scale-up, it is essential to reduce the unburnt compounds at the fuel reactor outlet. Proposals to achieve this reduction already exist and include both improvement to the gas-oxygen carrier contact, or new design concepts based on the current scheme for iG-CLC. In addition, CLOU based on copper materials has shown that complete fuel combustion could be achieved. Main challenges for the future development and scale-up of CLC technology have been also identified. A breakthrough in the future development of CLC technology for solid fuels will come from developing long-life materials for CLOU that are easy to recover from the ash purge stream.

L. Zeng, Zhuo Cheng, Jonathan A. Fan et al.

Luzhao Sun, Guowen Yuan, Libo Gao et al.

P. Gabrielli, M. Gazzani, M. Mazzotti

This contribution provides a conceptual analysis and a quantitative comparative assessment of three technology chains that enable a carbon neutral chemical industry in a net-zero-CO2 world. These a...

Jianlin Han, L. Kiss, Haibo Mei et al.

Over the last 100–120 years, due to the ever-increasing importance of fluorine-containing compounds in modern technology and daily life, the explosive development of the fluorochemical industry led to an enormous increase of emission of fluoride ions into the biosphere. This made it more and more important to understand the biological activities, metabolism, degradation, and possible environmental hazards of such substances. This comprehensive and critical review focuses on the effects of fluoride ions and organofluorine compounds (mainly pharmaceuticals and agrochemicals) on human health and the environment. To give a better overview, various connected topics are also discussed: reasons and trends of the advance of fluorine-containing pharmaceuticals and agrochemicals, metabolism of fluorinated drugs, withdrawn fluorinated drugs, natural sources of organic and inorganic fluorine compounds in the environment (including the biosphere), sources of fluoride intake, and finally biomarkers of fluoride exposure.

K. Dodo, K. Fujita, M. Sodeoka

In chemical biology research, various fluorescent probes have been developed and used to visualize target proteins or molecules in living cells and tissues, yet there are limitations to this technology, such as the limited number of colors that can be detected simultaneously. Recently, Raman spectroscopy has been applied in chemical biology to overcome such limitations. Raman spectroscopy detects the molecular vibrations reflecting the structures and chemical conditions of molecules in a sample and was originally used to directly visualize the chemical responses of endogenous molecules. However, our initial research to develop “Raman tags” opens a new avenue for the application of Raman spectroscopy in chemical biology. In this Perspective, we first introduce the label-free Raman imaging of biomolecules, illustrating the biological applications of Raman spectroscopy. Next, we highlight the application of Raman imaging of small molecules using Raman tags for chemical biology research. Finally, we discuss the development and potential of Raman probes, which represent the next-generation probes in chemical biology.

Muhammad Irwan Yanwari, Shogo Okamoto

Traditional tactile sensors primarily measure macroscopic surface features but do not directly estimate how humans perceive such surface roughness. Sensors that mimic human tactile processing could bridge this gap. This study proposes a method for predicting macroscopic roughness perception based on a sensing principle that closely resembles human tactile information processing. Humans are believed to assess macroscopic roughness based on the spatial distribution of subcutaneous deformation and resultant neural activities when touching a textured surface. To replicate this spatial-coding mechanism, we captured distributed contact information using a camera through a flexible, transparent material with fingerprint-like surface structures, simulating finger skin. Images were recorded under varying contact forces ranging from 1 N to 3 N. The spatial frequency components in the range of 0.1–1.0 mm⁻¹ were extracted from these contact images, and a linear combination of these components was used to approximate human roughness perception recorded via the magnitude estimation method. The results indicate that for roughness specimens with rectangular or circular protrusions of surface wavelengths between 2 and 5 mm, the estimated roughness values achieved an average error comparable to the standard deviation of participants’ roughness ratings. These findings demonstrate the potential of macroscopic roughness estimation based on human-like tactile information processing and highlight the viability of vision-based sensing in replicating human roughness perception.

WANG Jiawei(王佳薇), GONG Shuying(龚淑英), FAN Fangyuan(范方媛) et al.

Granular green tea is a significant category of famous high-quality green tea in Zhejiang Province. In this study, we conducted comparative experiments on key technical parameters, including moisture resurgence, second fixation and stir-frying techniques, during the primary processing of granular green tea and systematically analyzed their effects on sensory quality and chemical composition. The results indicated that appropriately controlling the rehumidification time (1.5 h), reducing the moisture content of the second fixed leaves (40%), decreasing the amount of tea leaves per frying pan (4 kg/pan), and selecting a frying pan with better air permeability (60-type) effectively enhanced the dry tea appearance and the emerald color of the tea liquor and improved the freshness of the aroma and taste. Moderate rehumidification and a lower moisture content in the second fixed leaves increased the content of catechins and some key umami amino acids, whereas a lower loading amount of tea leaves per frying pan increased the total amino acid content; a higher moisture content in the second fixed leaves increased the water extract content. Higher-quality samples with superior aroma and freshness had higher levels of floral compounds such as linalool, geraniol, and α-terpineol. Conversely, a longer rehumidification time, greater moisture content in the second fixed leaves, more tea leaves per frying pan, and lower air permeability of the stir-frying machine led to higher temperatures and moisture and increased the relative content of compounds such as n-hexadecanoic acid, heptanoic acid, and 6, 10, 14-trimethyl-2-pentadecanone in the aroma profile. In conclusion, this study identifies an optimal processing combination for improving the overall quality of granular green tea and provides a theoretical basis for refining its processing technology.(颗粒形绿茶是浙江省名优绿茶的重要品类。本研究针对颗粒形绿茶初制中回潮、二青、炒制等工序的关键技术参数开展对比试验，系统分析不同技术参数对颗粒形绿茶感官品质及化学组分的影响。结果表明，适当控制回潮时间（1.5 h）、降低二青叶含水率（40%）、适当减少炒制投叶量（4 kg/小锅）及选用透气性能较好的炒锅（60型），能够提升颗粒形绿茶外形及茶汤的翠绿色泽，并提高香气滋味的鲜爽性。适度回潮和较低的二青叶含水率有助于提升儿茶素含量及部分对鲜味具有重要贡献的氨基酸含量；较低的炒制投叶量可提升氨基酸总量；而较高的二青叶含水率则有利于提升水浸出物含量。在香气鲜爽性高、品质较优的样品中，芳樟醇、香叶醇、α-松油醇等具有花香特征的化合物的相对含量较高；而长时间回潮、较高的二青叶含水率、较高的炒制投叶量及较低透气性的锅型所引起的较高温度及含水率，则会促进正十六烷酸、庚酸、6，10，14-三甲基-2-十五烷酮等香气组分的积累。本研究明确了提升颗粒形绿茶综合品质的适宜工艺组合，为优化其加工技术提供了理论依据。)

Peixuan Sun, Ruiyuan Tang, Lixia He et al.

Amid growing concerns over fossil fuel depletion and environmental degradation, developing alternative energy sources is imperative. While MoS₂-based catalysts are known for their syngas conversion activity, their selectivity toward alcohols remains limited. This study addresses this gap by developing Cu-promoted MoS₂ catalysts to enhance alcohol synthesis. The results indicated that the introduction of copper significantly modulates the catalytic performance of MoS₂. We demonstrate that incorporating Cu significantly modulates the catalytic properties of MoS₂. The optimized catalyst with 9 wt% Cu loading exhibited a CO conversion of 17.9% and a markedly improved total alcohol selectivity of 46.4%, with a space-time yield of 67.6 mg·g⁻¹·h⁻¹. Although Cu addition slightly reduced CO conversion, it markedly improved alcohol selectivity by facilitating active site dispersion, suppressing Fischer-Tropsch side reactions, and stabilizing heteroatomic active phases. Finally, a catalytic mechanism for the synthesis of low-carbon alcohols from syngas on MoS₂-based catalysts was proposed based on the catalyst analysis and reaction results.

Nitin Thombre, Pritesh Patil, Ankita Yadav et al.

Abstract The textile industry is one of the important and largest industry that consumes major chunk of the water in the world. This industry produces a large amount of wastewater during the processes such as sizing, de-sizing, scouring, bleaching, mercerizing, dyeing, printing, and finishing. The used water produced after such processes affects the environment heavily due to its composition such as mineral salts and oils present in suspended state, metals and metal complexes, dyes, various chemicals, some readily-biodegradable products and some constituents that are hard to biodegrade. The treatment of such hazardous effluent to reuse the water in certain water demanding processes is essential. Considering the worldwide application of the textiles, the appropriate management of water resources in the sector includes the treatment of effluent by efficient technology and the reuse of the water. This article displays an overview of waste management during textile industrial processes. It aims at giving oversight on waste minimization and reuse along with wastewater treatment methods. It also involves the cross-utilization of effluent between processes for achieving water efficiency. This review covers advanced waterless textile dyeing processes, zero liquid discharge techniques, advanced oxidation processes, biological treatment methods, which can be a sustainable and greener approach to reducing the waste generation.