Electron‐Driven Self‐Assembly of Salt Nanocrystals in Liquid Helium

The self‐assembly of salt nanocrystals from chemical reactions inside liquid helium is reported for the first time. Reaction is initiated by an electron impacting a helium nanodroplet containing sodium atoms and SF₆ molecules, leading to preferential production of energetically favorable structures based on the unit cell of crystalline NaF. These favorable structures are observed as magic number ions (anomalously intense peaks) in mass spectra and are seen in both cationic and anionic channels in mass spectra, for example, (NaF)_nNa⁺ and (NaF)_nF^?. In the case of anions the self‐assembly is not directly initiated by electrons: the dominant process involves resonant electron‐induced production of metastable electronically excited He^? anions, which then initiate anionic chemistry by electron transfer.     

New Strategies on Green Synthesis of Dimethyl Carbonate from Carbon Dioxide and Methanol over Oxide Composites

Dimethyl carbonate is a generally used chemical substance which is environmentally sustainable in nature and used in a range of industrial applications as intermediate. Although various methods, including methanol phosgenation, transesterification and oxidative carbonylation of methanol, have been developed for large-scale industrial production of DMC, they are expensive, unsafe and use noxious raw materials. Green production of DMC from CO₂ and methanol is the most appropriate and eco-friendly method. Numerous catalysts were studied and tested in this regard. The issues of low yield and difficulty in tests have not been resolved fundamentally, which is caused by the inherent problems of the synthetic pathway and limitations imposed by thermodynamics. Electron-assisted activation of CO₂ and membrane reactors which can separate products in real-time giving a maximum yield of DMC are also being used in the quest to find more effective production method. In this review paper, we deeply addressed green production methods of DMC using Zr/Ce/Cu-based nanocomposites as catalysts. Moreover, the relationship between the structure and activity of catalysts, catalytic mechanisms, molecular activation and active sites identification of catalysts are also discussed.     

Professor Carl S. “speed” Marvel

Professor Marvel was one of the great polymer pioneers and innovators. He contributed throughout his lengthy career to every aspect of organic polymer chemistry. His many contributions and activities can be outlined in the following list: education; research; industrial consulting; government; american chemical society; awards; human being I shall discuss each of these in turn.     

Electrodialysis with Bipolar Membranes: Principles,Optimization, and Applications

This paper is an overview of the bipolar membrane technology. The process of electrodialysis with bipolar membrane (EDBM) along with the different EDBM process configurations are presented. Some ways of optimization of both the bipolar membranes and the EDBM technology are envisaged. Most of the applications relate to the production or recovery of organic acids while the first plant has been commissioned by 1986 at Washington Steel (USA) for the recovery of HF/HNO₃ from waste pickling liquors. In the last few years, there has been increasing interest in using bipolar electrodialysis stacks in chemical and agro industrial processes to directly acidify or basify process streams without the addition of chemicals. This attractive feature of this technology has contributed to the implementation of several plants in fermentation process for the production of organic and amino acids.     

Reaction of NO with hypochlorous acid

The reaction between NO(g) at concentrations between 0.1 and 1.0 Torr in 1-atm N₂ and aqueous solutions of NaClO has been studied over the pH range of 6–12 and hypochlorite concentrations between 0.01 and 1.0M. A very rapid and efficient reaction occurs leading to the production of about 30%–40% of the NO as NO₂ and with conversions of NO up to 98% at about 1-sec contact time. It is shown that a fast chain reaction initiated by the endothermic step can account for the data. The very exothermic reaction NO + ClO^? → NO₂ + Cl^? is shown to be at least 30-fold slower than i. The overall reaction seems very promising as a method of reducing NO and NO₂ emissions from the exhausts of industrial plants.     

Sustainable Surfactin Production by Bacillus subtilis Using Crude Glycerol from Different Wastes

Most biosurfactants are obtained using costly culture media and purification processes, which limits their wider industrial use. Sustainability of their production processes can be achieved, in part, by using cheap substrates found among agricultural and food wastes or byproducts. In the present study, crude glycerol, a raw material obtained from several industrial processes, was evaluated as a potential low-cost carbon source to reduce the costs of surfactin production by Bacillus subtilis #309. The culture medium containing soap-derived waste glycerol led to the best surfactin production, reaching about 2.8 g/L. To the best of our knowledge, this is the first report describing surfactin production by B. subtilis using stearin and soap wastes as carbon sources. A complete chemical characterization of surfactin analogs produced from the different waste glycerol samples was performed by liquid chromatography–mass spectrometry (LC-MS) and Fourier transform infrared spectroscopy (FTIR). Furthermore, the surfactin produced in the study exhibited good stability in a wide range of pH, salinity and temperatures, suggesting its potential for several applications in biotechnology.     

A preliminary information about continuous fermentation using cell recycling for improving microbial xylitol production rates

Xylitolis a sugar-alcohol with important technological properties, such as anticariogenicity, low caloric value, and negative dissolution heat. It can be used successfully in food for mulations and pharmaceutical industries. Its production is therefore in great demand. Biotechnological xylitol production has several economic advantages in comparison with the conventional process based on the chemical reduction of xylose. The efficiency and the productivity of this fermentation chiefly depends on the microorganism and the process conditions employed. In this article a simple continuous culture with cell recycling was evaluated to enhance the capability of Candida guilliermondii FTI 20037 to produce xylitol. The fermentation was initiated batchwise by directly inoculating the grown seed culturein a 2-L bench-scale fermentor. Continuous feeding was begun at a dilution rate (D) of 0.060/h after the xylose concentration had completely consumed and the cell concentration was a bout 4.0 g/L. At a dilution rate of 0.060/h the xylitol concentration was about 15g/L and in creased by about 35%, whereas the dilution rate decreased by about 58%. Furthermore, the volumetric productivity, Q_p, markedly depended on the dilution rate, diminishing by about 37% as D was changed from 0.060 to 0.025/h. These preliminary results show us that the continous fermentation with cell recycling is a good way to study the xylitol production by xylose-fermenting yeasts.     

Electron beam accelerators—trends in radiation processing technology for industrial and environmental applications in Latin America and the Caribbean

The radiation processing technology for industrial and environmental applications has been developed and used worldwide. In Latin America and the Caribbean and particularly in Brazil there are 24 and 16 industrial electron beam accelerators (EBA) respectively with energy from 200 keV to 10 MeV, operating in private companies and governmental institutions to enhance the physical and chemical properties of materials. However, there are more than 1500 high-current electron beam accelerators in commercial use throughout the world. The major needs and end-use markets for these electron beam (EB) units are R and D, wire and electric cables, heat shrinkable tubes and films, PE foams, tires, components, semiconductors and multilayer packaging films. Nowadays, the emerging opportunities in Latin America and the Caribbean are paints, adhesives and coatings cure in order to eliminate VOCs and for less energy use than thermal process; disinfestations of seeds; and films and multilayer packaging irradiation. For low-energy EBA (from 150 keV to 300 keV). For mid-energy EBA (from 300 keV to 5 MeV), they are flue gas treatment (SO₂ and NO_X removal); composite and nanocomposite materials; biodegradable composites based on biorenewable resources; human tissue sterilization; carbon and silicon carbide fibers irradiation; irradiated grafting ion-exchange membranes for fuel cells application; electrocatalysts nanoparticles production; and natural polymers irradiation and biodegradable blends production. For high-energy EBA (from 5 MeV to 10 MeV), they are sterilization of medical, pharmaceutical and biological products; gemstone enhancement; treatment of industrial and domestic effluents and sludge; preservation and disinfestations of foods and agricultural products; soil disinfestations; lignocellulosic material irradiation as a pretreatment to produce ethanol biofuel; decontamination of pesticide packing; solid residues remediation; organic compounds removal from wastewater; and treatment of effluent from petroleum production units and liquid irradiation process to treat vessel water ballast. On the other hand, there is a growing need of mobile EB facilities for different applications in South America.     

Effect of aerosol chemical vapor deposition on characteristics of MoS<Subscript>2</Subscript> particles

Influence exerted by the main technological parameters in the process in which nano- and microparticles of molybdenum disulfide are formed by the aerosol chemical vapor deposition method from a gas phase containing aerosol particles of (NH₄)₂MoS₄?C₃H₇NO solutions on the dimension characteristics, structure, and composition of the products being formed was studied. It was shown that the shape, size, and structure of the particles being formed are determined by the processes occurring in the first, streamwise, reactor zone. The temperature of this zone is the most important technological parameter. The concentration of ammonium thiomolybdate in solution makes it possible to gradually vary the size of disulfide particles in a wide range (from tens of nanometers to micrometers). In the conditions under study, the technological conditions have no effect on the chemical composition of the products being synthesized, which is always described by the formula MoS₂. The results obtained can be used in development of industrial apparatus and technology for synthesis of molybdenum disulfide nano- and microparticles to be used as the antifriction component of lubricating materials.     

Synthesis of Densely Packaged,Ultrasmall Pt02 Clusters within a Thioether‐Functionalized MOF: Catalytic Activity in Industrial Reactions at Low Temperature

The gram‐scale synthesis, stabilization, and characterization of well‐defined ultrasmall subnanometric catalytic clusters on solids is a challenge. The chemical synthesis and X‐ray snapshots of Pt⁰₂ clusters, homogenously distributed and densely packaged within the channels of a metal–organic framework, is presented. This hybrid material catalyzes efficiently, and even more importantly from an economic and environmental viewpoint, at low temperature (25 to 140 °C), energetically costly industrial reactions in the gas phase such as HCN production, CO₂ methanation, and alkene hydrogenations. These results open the way for the design of precisely defined catalytically active ultrasmall metal clusters in solids for technically easier, cheaper, and dramatically less‐dangerous industrial reactions.     

Synthesis of Densely Packaged,Ultrasmall Pt02 Clusters within a Thioether‐Functionalized MOF: Catalytic Activity in Industrial Reactions at Low Temperature

The gram‐scale synthesis, stabilization, and characterization of well‐defined ultrasmall subnanometric catalytic clusters on solids is a challenge. The chemical synthesis and X‐ray snapshots of Pt⁰₂ clusters, homogenously distributed and densely packaged within the channels of a metal–organic framework, is presented. This hybrid material catalyzes efficiently, and even more importantly from an economic and environmental viewpoint, at low temperature (25 to 140 °C), energetically costly industrial reactions in the gas phase such as HCN production, CO₂ methanation, and alkene hydrogenations. These results open the way for the design of precisely defined catalytically active ultrasmall metal clusters in solids for technically easier, cheaper, and dramatically less‐dangerous industrial reactions.     

2,4-Difluoro anisole: a promising complexing agent for boron isotopes separation by chemical exchange reaction and distillation

Although methods of boron isotopes separation were intensively pursued about 60 years, the chemical exchange distillation is the only method that has been applied in industrial scale production of ¹⁰B. The present anisole BF₃ system suffers from the drawbacks like high melting point, relatively low separation coefficient and instability under reaction conditions, which demand a continuous search for more effective and efficient donors for boron isotope separation. A series of fluoro-substituted anisole derivatives were screened in this paper, among which 2,4-difluoro anisole exhibited good properties compared with anisole. Studies on the boron trifluoride and 2,4-difluoro anisole adduct, its thermodynamic and physical properties related to large-scale isotopic separation is reported. The results showed that 2,4-difluoro anisole is better than anisole in separation coefficient, freezing point and stability under pyrolysis conditions, which suggest a further detailed investigations on boron trifluoride and 2,4-difluoro anisole adduct.     

Integration of commercial CO2 capture plant with primary reformer stack of ammonia plant

The safety of primary reformers is essential to safe operation of large-scale petrochemical processes, especially when carbon dioxide is going to be recovered from an ammonia plant. In this study, a preliminary assessment is made to model an industrial stack as the stack gases are introduced into CO₂ capture plant, during ammonia production. A CFD model was first developed in the absence of a commercial carbon dioxide recovery (CDR) unit to validate the model against industrial data under normal operation. At full capacity of the ammonia plan, the results provided by the CFD model match the measurement results well within about 3.87% margin of relative error. The calibrated model was then applied in combination with post-combustion, as part of the process, to verify the process safety constraints in reformer furnace. The effect of starting up and shutting down of CDR plant was explored in the event of emergency operation. From an operational view, in the event of startup or unplanned failure of the CO₂ capture plant, the pressure fluctuations do not exceed the maximum allowable pressure of the firebox. Upon reaching the required operating conditions, both subsystems can be integrated operationally to continue production safely.

     

(±)‐2,2‐Dimethyl‐5‐oxotetrahydrofuran‐3‐carboxylic acid (terebic acid): a racemic layered structure

A racemic crystalline form of terebic acid, C₇H₁₀O₄, which is an important industrial chemical compound, is reported for the first time. The crystal structure is stabilized by O—H...O and C—H...O hydrogen bonds which form racemic double layers parallel to (001).     

Efficient Non‐dissociative Activation of Dinitrogen to Ammonia over Lithium‐Promoted Ruthenium Nanoparticles at Low Pressure

There is an exciting possibility to decentralize ammonia synthesis for fertilizer production or energy storage without carbon emission from H₂ obtained from renewables at small units operated at lower pressure. However, no suitable catalyst has yet been developed. Ru catalysts are known to be promoted by heavier alkali dopants. Instead of using heavy alkali metals, Li is herein shown to give the highest rate through surface polarisation despite its poorest electron donating ability. This exceptional promotion rate makes Ru–Li catalysts suitable for ammonia synthesis, which outclasses industrial Fe counterparts by at least 195 fold. Akin to enzyme catalysis, it is for the first time shown that Ru–Li catalysts hydrogenate end‐on adsorbed N₂ stabilized by Li⁺ on Ru terrace sites to ammonia in a stepwise manner, in contrast to typical N₂ dissociation on stepped sites adopted by Ru–Cs counterparts, giving new insights in activating N₂ by metallic catalysts.     

Thiophene-Containing Covalent Organic Frameworks for Overall Photocatalytic H2O2 Synthesis in Water and Seawater

H₂O₂ is a significant chemical widely utilized in the environmental and industrial fields, with growing global demand. Without sacrificial agents, simultaneous photocatalyzed H₂O₂ synthesis through the oxygen reduction reaction (ORR) and water oxidation reaction (WOR) dual channels from seawater is green and sustainable but still challenging. Herein, two novel thiophene-containing covalent organic frameworks (TD-COF and TT-COF) were first constructed and served as catalysts for H₂O₂ synthesis via indirect 2e⁻ ORR and direct 2e⁻ WOR channels. The photocatalytic H₂O₂ production performance can be regulated by adjusting the N-heterocycle modules (pyridine and triazine) in COFs. Notably, with no sacrificial agents, just using air and water as raw materials, TD-COF exhibited high H₂O₂ production yields of 4060 μmol h⁻¹ g⁻¹ and 3364 μmol h⁻¹ g⁻¹ in deionized water and natural seawater, respectively. Further computational mechanism studies revealed that the thiophene was the primary photoreduction unit for ORR, while the benzene ring (linked to the thiophene by the imine bond) was the central photooxidation unit for WOR. The current work exploits thiophene-containing COFs for overall photocatalytic H₂O₂ synthesis via ORR and WOR dual channels and provides fresh insight into creating innovative catalysts for photocatalyzing H₂O₂ synthesis.     

Towards Green Ammonia Synthesis through Plasma-Driven Nitrogen Oxidation and Catalytic Reduction

Ammonia is an industrial large-volume chemical, with its main application in fertilizer production. It also attracts increasing attention as a green-energy vector. Over the past century, ammonia production has been dominated by the Haber–Bosch process, in which a mixture of nitrogen and hydrogen gas is converted to ammonia at high temperatures and pressures. Haber–Bosch processes with natural gas as the source of hydrogen are responsible for a significant share of the global CO₂ emissions. Processes involving plasma are currently being investigated as an alternative for decentralized ammonia production powered by renewable energy sources. In this work, we present the PNOCRA process (plasma nitrogen oxidation and catalytic reduction to ammonia), combining plasma-assisted nitrogen oxidation and lean NO_x trap technology, adopted from diesel-engine exhaust gas aftertreatment technology. PNOCRA achieves an energy requirement of 4.6 MJ mol⁻¹ NH₃, which is more than four times less than the state-of-the-art plasma-enabled ammonia synthesis from N₂ and H₂ with reasonable yield (>1 %).     

Production of bacterial cellulose from alternative low-cost substrates

Cellulose is the most widely used biopolymer on Earth. Its large-scale production is mainly from lignocellulosic material (plant origin), however, this plant material is not the only source of this valuable polymer, since microorganisms, like bacteria, naturally produce cellulose, especially those of the genus Komagateibacter (formerly Gluconacetobacter). This type of cellulose is of great interest because of its unique properties such as high purity and resistance, nevertheless, it has not been produced in a large-scale industrial process to date using low-cost substrates, one of the key aspects that should be considered for the industrial obtaining of any biotechnological product. As a main finding we found that the majority of low-cost culture media discussed could have the potential to produce bacterial cellulose on an industrial scale, since in most cases they yield more cellulose (with similar physical chemical characteristics) to those obtained in standard media. However, for an appropriate large-scale production, a specific knowledge about these by-products (since their composition and characteristics, which have a direct impact on the productivity of this biopolymer, are quite heterogeneous) and a proper standardization of them would also be required. Research staff of many industries could use the information presented here to help design a process to use their respective byproducts as substrate to obtain a product with a high added value as bacterial cellulose.     

Novel NO2 Gas Sensor Based on Cr(III) Complex Thin Film

The results concerning the gas‐sensing characteristics of novel NO₂ gas sensors, fabricated from complex [Cr(bipyO₂)Cl₂]Cl thin films, were first presented. The sensors exhibited high response to NO₂ gas in the concentration range from 1.97% to 6.67% at relative low temperatures (from room temperature to 348 K). No response to H₂S and SO₂ was observed. The maximum response for 6.03% NO₂ was approximately 11.7 at 338 K and 10 V operating voltage. The response time of the sensors was about 4.5 min for NO₂ and the recovery time about 40 s. The effect of the electrical resistance change of the sensors in the presence of NO₂ could be used for gas sensing measurements. The performance and reliability of the sensors showed their potential applications for monitoring and controlling NO₂ component continuously in chemical production.     

Chemical bonding in isostructural Li-containing ternary chalcogenides

First principle calculations were performed for the first time to study the electronic structure of LiGaTe₂, LiInTe₂, and LiInSe₂ chalcogenides with a chalcopyrite structure. Peculiarities of chemical bonding are discussed and electron density and difference density maps are constructed for crystals and sublattices. Major information about chemical bonding in crystals is conveyed by the difference density. The chemical bond in chalcogenides is a donor-acceptor bond.