Multiscale porous single-atom Co catalysts for epoxidation by O2

Author(s):  
Xiao Chen ◽  
Yong Zou ◽  
Mingkai Zhang ◽  
Wangyan Gou ◽  
Sai Zhang ◽  
...  

Epoxides are versatile intermediates in the production of a diverse set of chemical products. Direct epoxidation of alkene using O2 represents an environmentally friendly and economical process to replace the...

2020 ◽  
pp. 016224392096494
Author(s):  
Elsa Faugère ◽  
Dorothée Dussy

Over the last few years, the amount of space occupied by bees in the French public debate together with the well-known benefits of the products of their hive has attracted the interest of social scientists. Indeed, bees have become a symbol of the biodiversity crisis. Social scientists, like us, are sometimes invited to join multidisciplinary projects run by biologists specializing in bees. The aim of such involvement is to help the biologists to convince professional beekeepers to make their practices greener, notably with respect to their handling of the Varroa mite. However, the beekeepers we studied in the south of France are not keen to give up their conventional practices. Based on chemical products, these are efficient, simple, and cheap as opposed to environmentally friendly, chemical-free techniques (scraping or removal of the brood), which are seen to be riskier and more complicated to implement. This article describes and analyzes these obstacles and the relationship to scientific and nonscientific knowledge they reveal.


2021 ◽  
pp. 2102843
Author(s):  
Xin Zhou ◽  
Imgon Hwang ◽  
Ondřej Tomanec ◽  
Dominik Fehn ◽  
Anca Mazare ◽  
...  

Research ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Ruixuan Qin ◽  
Pei Wang ◽  
Pengxin Liu ◽  
Shiguang Mo ◽  
Yue Gong ◽  
...  

Size effect plays a crucial role in catalytic hydrogenation. The highly dispersed ultrasmall clusters with a limited number of metal atoms are one candidate of the next generation catalysts that bridge the single-atom metal catalysts and metal nanoparticles. However, for the unfavorable electronic property and their interaction with the substrates, they usually exhibit sluggish activity. Taking advantage of the small size, their catalytic property would be mediated by surface binding species. The combination of metal cluster coordination chemistry brings new opportunity. CO poisoning is notorious for Pt group metal catalysts as the strong adsorption of CO would block the active centers. In this work, we will demonstrate that CO could serve as a promoter for the catalytic hydrogenation when ultrasmall Pd clusters are employed. By means of DFT calculations, we show that Pdn n=2‐147 clusters display sluggish activity for hydrogenation due to the too strong binding of hydrogen atom and reaction intermediates thereon, whereas introducing CO would reduce the binding energies of vicinal sites, thus enhancing the hydrogenation reaction. Experimentally, supported Pd2CO catalysts are fabricated by depositing preestablished [Pd2(μ-CO)2Cl4]2- clusters on oxides and demonstrated as an outstanding catalyst for the hydrogenation of styrene. The promoting effect of CO is further verified experimentally by removing and reintroducing a proper amount of CO on the Pd cluster catalysts.


Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1303
Author(s):  
Chao Luo ◽  
Tian Yang ◽  
Qianfei Huang ◽  
Xian Liu ◽  
Huan Ling ◽  
...  

The photoreduction of carbon dioxide (CO2) to valuable fuels is a promising strategy for the prevention of rising atmospheric levels of CO2 and the depletion of fossil fuel reserves. However, most reported photocatalysts are only active in the ultraviolet region, which necessitates co-catalysts and sacrificial agents in the reaction systems, leading to an unsatisfied economy of the process in energy and atoms. In this research, a CuMoxW(1-x)O4 solid solution was synthesized, characterized, and tested for the photocatalytic reduction of CO2 in the presence of amines. The results revealed that the yield of CH3OH from CO2 was 1017.7 μmol/g under 24 h visible light irradiation using CuW0.7Mo0.3O4 (x = 0.7) as the catalyst. This was associated with the maximum conversion (82.1%) of benzylamine to N-benzylidene benzylamine with high selectivity (>99%). These results give new insight into the photocatalytic reduction of CO2 for valuable chemical products in an economic way.


2013 ◽  
Vol 781-784 ◽  
pp. 1998-2002
Author(s):  
Peng Wang ◽  
Xiao An Wei ◽  
Wei Dong He ◽  
Yan Long Shi

As a kind of particular hazardous materials, waste or expired gun propellants must be properly disposed. The applications of reusing waste gun propellants in the industry of china were summarized. Some disposal technologies were also introduced. Waste gun propellants were not only transformed into some chemical products and civil special energies, but also they were reused as ingredients in different kinds of industrial explosives. Among those the incorporation of propellants into industry explosives offers the most economically effective, safe and environmentally friendly method. This paper also suggests that the trend for disposing energetic materials is resource, recovery and reuse (R3) technology.


2013 ◽  
Vol 785-786 ◽  
pp. 823-826
Author(s):  
Li Qiu Wang ◽  
Li Hui Zheng ◽  
Yang Liu ◽  
Shu Ping Sun ◽  
Peng Jun Wang ◽  
...  

Two-membrane-pieces sensitizing method and the corresponding equipments were developed to prepare cyanines sensitized nanoTiO2 photo anode materials. The cyanines were synthesized from N-p-carboxybenzyl-2,3,3-trimethyl-3H-indoleninium-5-sulfonate potassium and squaric acid or 2-chloro-1-formyl-3-(hydroxymethylene) cyclohex-1-ene. The maximum UV-Vis absorption wavelengths of them were 631 nm and 782 nm, respectively. The nanoTiO2 thin films were prepared on ITO conductive glass from tetrabutyl titanate by sol-gel technique, and were sensitized with the dyes by two-membrane-pieces dye sensitizing method or immersion sensitizing method. Compared with traditional immersion sensitizing method, two-membrane-pieces sensitizing method was an environmentally friendly and economical process due to less dye consumption and less waste formed.


Author(s):  
Эльза Фожер ◽  
Дороте Дюсси

Пчелы и широко известные полезные свойства продуктов пчеловодства, которым в общественных дискуссиях во Франции уделялось и уделяется значительное внимание, в течение нескольких предыдущих лет стали предметом интереса французских социальных исследователей. Пчелы фактически превратились в символ кризиса биоразнообразия в стране. Социальные исследовате-ли, включая авторов данной статьи, иногда участвуют в мультидисциплинарных проектах под ру-ководством биологов с целью помочь убедить профессиональных пчеловодов внедрять более эко-логичные практики пчеловодства, особенно в том, что касается борьбы с клещом Варроа – смер-тоносным вредителем пчел. Однако, как выяснилось в ходе нашего исследования на юге Фран-ции, местные пчеловоды не спешат отказываться от привычных методов своей работы. Они про-должают использовать химикаты, которые просты в обращении, дешевы и эффективны, игнори-руя при этом более экологически безопасные, но, по их мнению, более рискованные и сложные в применении техники, такие, как чистка или удаление части пчелиного расплода. В данной статье нами анализируются препятствия на пути внедрения более экологичного пчеловодства во Фран-ции, и исследуется отношение к научному и ненаучному знанию, которое эти препятствия обна-руживают. Over the last few years the amount of space occupied by bees in the French public debate together with the well-known benefits of the products of their hive has attracted the interest of social scien-tists. Indeed, bees have become a symbol of the biodiversity crisis. Social scientists, like us, are sometimes invited to join multi-disciplinary projects run by biologists specializing in bees. The aim of such involvement is to help the biologists convince professional beekeepers to make their practices greener, notably with respect to their handling of the Varroa mite. However, the bee-keepers we studied in the South of France are not keen to give up their conventional practices. Based on chemical products, these are efficient, simple and cheap as opposed to environmentally-friendly, chemical-free techniques (scraping or removal of the brood), which are seen to be riskier and more complicated to implement. This article describes and analyses these obstacles and the relationship to scientific and non-scientific knowledge they reveal.


Author(s):  
Pianpian Zhang ◽  
Xiaoning Zhan ◽  
Lianbin Xu ◽  
Xianzhang Fu ◽  
Tianyu Zheng ◽  
...  

The photocatalytic reduction of carbon dioxide (CO2RR) into value-added chemical products is a promising way to enrich energy supply and reduce CO2 emission. The proposal of a high-efficiency, low-cost and...


2021 ◽  
Author(s):  
Sara Gücyeter ◽  
Richard Erpelding ◽  
Magnus S. Schmidt

AbstractLignin is a potentially high natural source of biological aromatic substances. However, decomposition of the polymer has proven to be quite challenging, as the complex bonds are fairly difficult to break down chemically. This article is intended to provide an overview of various recent methods for the catalytic chemical depolymerization of the biopolymer lignin into chemical products. For this purpose, nickel-, zeolite- and palladium-supported catalysts were examined in detail. In order to achieve this, various experiments of the last years were collected, and the efficiency of the individual catalysts was examined. This included evaluating the reaction conditions under which the catalysts work most efficiently. The influence of co-catalysts and Lewis acidity was also investigated. The results show that it is possible to control the obtained product selectivity very well by the choice of the respective catalysts combined with the proper reaction conditions.


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