Zn‐ and Na‐modulated Fe catalysts were fabricated by a simple coprecipitation/washing method. Zn greatly changed the size of iron species, serving as the structural promoter, while the existence of ...Na on the surface of the Fe catalyst alters the electronic structure, making the catalyst very active for CO activation. Most importantly, the electronic structure of the catalyst surface suppresses the hydrogenation of double bonds and promotes desorption of products, which renders the catalyst unexpectedly reactive toward alkenes—especially C5+ alkenes (with more than 50% selectivity in hydrocarbons)—while lowering the selectivity for undesired products. This study enriches C1 chemistry and the design of highly selective new catalysts for high‐value chemicals.
Direct synthesis of olefins using Fe‐based catalysts is a component of the traditional Fischer–Tropsch process. Na‐doping of Fe catalysts alters the surface electronic structure, which promotes CO activation and desorption of products, while suppressing hydrogenation of double bonds. A Na‐modulated catalyst is especially selective for alkenes (particularly C5+).
Solidified natural gas (SNG) is a promising option to store natural gas in the form of clathrate hydrates because of several benefits offered that include high degree of safety, eco-friendliness, ...high volumetric storage capacity, and the relative ease of gas recovery. Environmentally benign amino acids have been reported as promising kinetic promoters for enhancing methane hydrate formation. In this work, we examine in detail the effect of three different types of amino acidstryptophan (nonpolar, hydrophobic amino acid with aromatic side chain), histidine (polar, basic amino acid with aromatic side chain), and arginine (polar, basic amino acid with aliphatic side chain)on the kinetics of methane hydrate formation. The effect of amino acid concentration on the hydrate formation kinetics was investigated in two reactor configurations, namely, stirred and unstirred tank reactors. Amongst the amino acids studied, the best kinetic promotion for methane hydrate formation (in both stirred and unstirred reactor configurations) was achieved by tryptophan. The optimal concentration for best kinetic promotion of methane hydrate formation varies with the amino acid for same operating conditions. It may be inferred that the presence of an aromatic side chain and hydrophobic nature resulted in a better enhancement of methane hydrate formation.
The development of affordable electrocatalysts that can drive the reduction of CO2 to CO with high selectivity, efficiency, and large current densities is a critical step on the path to production of ...liquid carbon-based fuels. In this work, we show that inexpensive triflate salts of Sn2+, Pb2+, Bi3+, and Sb3+ can be used as precursors for the electrodeposition of CO2 reduction cathode materials from MeCN solutions, providing a general and facile electrodeposition strategy, which streamlines catalyst synthesis. The ability of these four platforms to drive the formation of CO from CO2 in the presence of BMIMOTf was probed. The electrochemically prepared Sn and Bi catalysts proved to be highly active, selective, and robust platforms for CO evolution, with partial current densities of j CO = 5–8 mA/cm2 at applied overpotentials of η < 250 mV. By contrast, the electrodeposited Pb and Sb catalysts do not promote rapid CO generation with the same level of selectivity. The Pb material is only ∼10% as active as the Sn and Bi systems at an applied potential of E = −1.95 V and is rapidly passivated during catalysis. The Sb-comprised cathode material shows no activity for conversion of CO2 to CO under analogous conditions. When taken together, this work demonstrates that 1,3-dialkylimidazoliums can promote CO production, but only when used in combination with an appropriately chosen electrocatalyst material. More broadly, these results suggest that the interactions between CO2, the imidazolium promoter, and the cathode surface are all critical to the observed catalysis.
The first thiocarboxylation of styrenes and acrylates with CO2 was realized by using visible light as a driving force and catalytic iron salts as promoters. A variety of important β‐thioacids were ...obtained in high yields. This multicomponent reaction proceeds in an atom‐ and redox‐economical manner with broad substrate scope under mild reaction conditions. Notably, high regio‐, chemo‐, and diasteroselectivity are observed. Mechanistic studies indicate that a radical pathway can account for the unusual regioselectivity.
One flew over the COO→ ‐COOH's nest: The first thiocarboxylation of styrenes and acrylates with CO2 to generate important β‐thioacids was realized by using visible light as a driving force and catalytic iron salts as promoters. This multicomponent reaction features broad substrate scope, mild reaction conditions, and high regio‐, chemo‐, and diasteroselectivity. Mechanistic studies indicate that a radical pathway can account for the unusual regioselectivity.
The occurrence of antibiotics and antibiotic resistance genes in riverine systems has become a growing concern worldwide. Risk prediction of antibiotic resistance is difficult as the continuous ...addition of new antibiotics complicate the antibiotic resistome. As rivers flow with heavy antibiotic burdens, antibiotic resistance develops rapidly and disseminates into various environmental compartments. The analysis of antibiotic contamination-driven resistance in global rivers provides a clear picture of the consequences in the near future. In this review, an extensive literature survey along with the analysis on the relevant data was carried out to offer a better knowledge on the global trend of antibiotic resistance. Although the most common resistance was reported against tetracycline and sulfonamide class of antibiotics, the trend of resistance against advanced generation antibiotics such as β-lactam is alarming. Furthermore, non-therapeutic use of antibiotics as growth promoters has become more frequent than clinical use as a major driver of resistance dissemination. Mechanistically, integrons and mobile genetic elements are suggested as one of the important media for resistance gene transfer. Considering the significance of this emerging issue, special emphasis is placed on the sources, fate, and possible management strategies to mitigate the threat of antibiotic resistance. This review covers the environmental footprints of the antibiotic contamination-mediated emergence and dissemination of antibiotic resistant bacteria and genes in global rivers. As such, the distribution pattern of antibiotic contamination and resistance determinants in various rivers worldwide has been described with a note of its long term impact. The information presented in this review may be useful to policy makers, clinicians, and pharmaceutical companies to tackle the epidemiology of antibiotic resistance as a global threat.
•The data on dissemination of important antibiotics, ARB and ARGs in major rivers are assessed.•The results suggest that antibiotic resistance is an emerging global threat.•Wastewater effluents are major sources of antibiotic resistance dissemination.•Methods of wastewater treatment should be improved for the efficient removal of antibiotics.
Autophagy, as a type II programmed cell death, plays crucial roles with autophagy-related (ATG) proteins in cancer. Up to now, the dual role of autophagy both in cancer progression and inhibition ...remains controversial, in which the numerous ATG proteins and their core complexes including ULK1/2 kinase core complex, autophagy-specific class III PI3K complex, ATG9A trafficking system, ATG12 and LC3 ubiquitin-like conjugation systems, give multiple activities of autophagy pathway and are involved in autophagy initiation, nucleation, elongation, maturation, fusion and degradation. Autophagy plays a dynamic tumor-suppressive or tumor-promoting role in different contexts and stages of cancer development. In the early tumorigenesis, autophagy, as a survival pathway and quality-control mechanism, prevents tumor initiation and suppresses cancer progression. Once the tumors progress to late stage and are established and subjected to the environmental stresses, autophagy, as a dynamic degradation and recycling system, contributes to the survival and growth of the established tumors and promotes aggressiveness of the cancers by facilitating metastasis. This indicates that regulation of autophagy can be used as effective interventional strategies for cancer therapy.
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•Works on Ru catalysts with alkali promoters for NH3 synthesis are reviewed.•The concept of electron donation and nature of the adsorbed species are examined.•Kinetic analysis over Ru ...catalysts are performed with relating to the mechanism.•Mechanism of ammonia synthesis over ruthenium catalysts is proposed.
Previous research on ammonia synthesis over ruthenium catalysts is reviewed with a particular emphasis on the action of alkali promoters. The concept of electron donation and the nature of the adsorbed species are examined, and their relationship with electronic and structural factors related to dinitrogen activation is considered. A kinetic analysis is performed and the reaction mechanism involved in ammonia synthesis over ruthenium catalysts is investigated.
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•Plasma biogas reforming over K-, Ce- and Mg-promoted catalysts was carried out.•Plasma-alone, catalysis-alone and plasma-catalysis modes were evaluated.•Plasma-catalytic coupling ...showed a synergy in conversion and energy efficiency.•Adding promotors to Ni catalyst enhanced the conversion of reactants.•The promoted Ni catalysts increased carbon deposition on the catalysts.
Plasma-catalytic biogas reforming over Ni-X/Al2O3 catalyst (X=K, Mg and Ce) has been carried out in a coaxial dielectric barrier discharge (DBD) plasma reactor at 160°C. Three different process modes: plasma-alone, catalysis-alone and plasma-catalysis have been investigated to get new insights into the synergistic effect resulted from the interaction of the plasma with the promoted Ni catalysts. Compared to the biogas reforming using either plasma-alone or catalysis-alone mode at the same temperature (160°C), the combination of the plasma with the Ni-based catalysts exhibited a low temperature synergistic effect, as evidenced from the much higher reforming performance of the plasma-catalytic process compared to that of the sum of the individual processes (plasma-alone and catalysis-alone). The addition of promoters (K, Mg and Ce) into the Ni/Al2O3 catalyst enhanced the conversion of CH4, the yield of H2 and the energy efficiency of the plasma process. In this study, the behaviour of K, Mg and Ce promoters in the low temperature plasma-catalytic biogas reforming was clearly different from that in high temperature thermal catalytic process in terms of the conversion of CH4 and carbon deposition, which could be ascribed to the temperature-dependent character of the promotors. In the plasma-catalytic biogas reforming, the Ni-K/Al2O3 catalyst showed the best performance, enhancing the conversion of both CO2 and CH4, the yield of H2, CO and C2–C4 alkanes and the energy efficiency of the plasma process. The highest conversion of CO2 (22.8%) and CH4 (31.6%) was achieved by placing the K-promoted catalyst in the plasma reforming process. The Mg-promoted catalyst remarkably increased the H2/CO molar ratio in the gas products (up to 2.2) due to the decreased CO2 conversion. In addition, compared to the un-promoted Ni/Al2O3 catalyst, although the use of the promoted catalysts increased the carbon deposition on the surface of the spent catalysts by 22%–26%, the total amount of deposited carbon was still less than that reported in high temperature catalytic dry reforming processes. More than 80% of the increased carbonaceous species was in the form of reactive carbon species, which can be easily oxidized by CO2 and O atoms and maintain the stability of the catalysts during the reforming reaction.
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•Industrial installations for eliminating dioxins from flue gas.•Mechanisms of catalytic oxidation of chloroaromatics.•Catalyst classification and adaptation.•Catalyst deactivation ...and possible regeneration.•Miscellaneous methods to improve the catalytic oxidation process.
Commercial catalysts for the catalytic oxidation of chloroaromatics are mainly based on either noble metals or transition metal oxides supported on a suitable carrier. This paper reviews studies relative to these two generic groups of catalysts and their performances for chloroaromatic decomposition, i.e. conversion efficiency, stability and selectivity towards harmless products (e.g., CO2), and in particular, avoiding the formation of polychlorinated by-products. The various approaches towards improved catalysts, including tuning the support, adding dopants or promoters, improving the preparation methods, or auxiliary means such as the introduction of ozone (O3) or hydrogen peroxide (H2O2) in the gas to be treated, and combination with non-thermal plasma treatment are systematically reviewed. This review also appraises various modes of deactivation (i.e., originating from fouling, coking, poisoning, sintering of the catalyst, and from volatilization of its active phases) as well as possible methods for regeneration.
A steady increase in atmospheric carbon dioxide (CO2) and methane concentrations in recent decades has sparked interest among researchers around the globe to find quick solutions to this problem. One ...viable option is a utilization of CO2 with methane to produce syngas via catalytic reforming. In this paper, a comprehensive review has been conducted on the role and performance of Ni-based catalysts in the CO2 reforming of methane (sometimes called dry reforming of methane, DRM). Coke-resistance is the key ingredient in good catalyst formulation; it is, therefore, paramount in a choice of catalyst supports, promoters, and reaction conditions. Catalyst supports that have a strong metal-support interaction created during the catalyst preparation exhibit highest stability, high thermal resistance and high coke resistance. In addition, the outlook of the Ni-based catalysts has been proposed to provide researchers with critical information related to the future direction of Ni-based catalysts in industrial settings. Among others, it has been a great interest among researchers to synthesize catalyst supports from cellulosic materials (plant-based materials). The unique properties of the cellulose which are a well-defined structure and superior mechanical strength could enhance the catalytic activity in the DRM reaction.
•Potential bimetallic Ni-based catalyst for dry reforming of methane (DRM).•Recent trend in dry reforming of methane using Ni-based catalysts.•Comprehensive review on role and performance of Ni-based catalyst for DRM.•Modification of Ni-based catalyst to enhance activity, conversion, yield of syngas.•Future outlook of Ni-based catalyst for DRM.
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