Catalytic Activity of Bulk Tungsten Carbides for Alkane Reforming. III. Reaction Mechanisms and the Kinetic Model

The presence of bromate in water sources generates environmental concern due to its toxicity for humans. Diverse technologies, like membranes, ion exchange, chemical reduction, etc., can be employed to treat bromate-polluted water but they produce waste that must be treated. An alternative to these technologies can be the catalytic reduction of bromate to bromide using hydrogen as a reducing agent. In this review, we analyze the research published about this catalytic technology. Specifically, we summarize and discuss about the state of knowledge related to (1) the different metals used as catalysts for the reaction; (2) the influence of the support on the catalytic activity; (3) the characterization of the catalysts; (4) the reaction mechanisms; and (5) the influence of the water composition in the catalytic activity and in the catalyst stability. Based on published papers, we analyze the strength and weaknesses of this technique and the possibilities of using this reaction for the treatment of bromate-polluted water as a sustainable process.

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Iron catalysts with N-ligands for carbene transfer of diazo reagents

Chemical Society Reviews ◽

10.1039/d0cs00221f ◽

2020 ◽

Vol 49 (14) ◽

pp. 4867-4905 ◽

Cited By ~ 4

Author(s):

Caterina Damiano ◽

Paolo Sonzini ◽

Emma Gallo

Keyword(s):

Catalytic Activity ◽

Reaction Mechanisms ◽

Iron Complexes ◽

Iron Catalysts ◽

Nitrogen Ligands ◽

Carbene Transfer ◽

Diazo Reagents

This review provides an overview of the catalytic activity of iron complexes of nitrogen ligands in driving carbene transfers towards CC, C–H and X–H bonds. The reactivity of diazo reagents is discussed as well as the proposed reaction mechanisms.

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Control of the catalytic activity of tungsten carbides II. Physicochemical characterizations of tungsten carbides

Journal of Catalysis ◽

10.1016/0021-9517(86)90367-2 ◽

1986 ◽

Vol 99 (2) ◽

pp. 428-438 ◽

Cited By ~ 24

Author(s):

B VIDICK

Keyword(s):

Catalytic Activity ◽

Tungsten Carbides

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Sulfur Vulcanization of Natural Rubber for Benzothiazole Accelerated Formulations: From Reaction Mechanisms to a Rational Kinetic Model

Rubber Chemistry and Technology ◽

10.5254/1.3547762 ◽

2003 ◽

Vol 76 (3) ◽

pp. 592-693 ◽

Cited By ~ 123

Author(s):

Prasenjeet Ghosh ◽

Santhoji Katare ◽

Priyan Patkar ◽

James M. Caruthers ◽

Venkat Venkatasubramanian ◽

...

Keyword(s):

Kinetic Model ◽

Natural Rubber ◽

Reaction Mechanisms ◽

Population Balance ◽

Balance Model ◽

Population Balance Model ◽

Wide Range ◽

Sulfur Vulcanization ◽

Vulcanization Process ◽

Single Set

Abstract The chemistry of accelerated sulfur vulcanization is reviewed and a fundamental kinetic model for the vulcanization process is developed. The vulcanization of natural rubber by the benzothiazolesulfenamide class of accelerators is studied, where 2-(morpholinothio) benzothiazole (MBS) has been chosen as the representative accelerator. The reaction mechanisms that have been proposed for the different steps in vulcanization chemistry are critically evaluated with the objective of developing a holistic description of the governing chemistry, where the mechanisms are consistent for all reaction steps in the vulcanization process. A fundamental kinetic model has been developed for accelerated sulfur vulcanization, using population balance methods that explicitly acknowledge the polysulfidic nature of the crosslinks and various reactive intermediates. The kinetic model can accurately describe the complete cure response including the scorch delay, curing and the reversion for a wide range of compositions, using a single set of rate constants. In addition, the concentration profiles of all the reaction intermediates as a function of polysulfidic lengths are predicted. This detailed information obtained from the population balance model is used to critically examine various mechanisms that have been proposed to describe accelerated sulfur vulcanization. The population balance model provides a quantitative framework for explicitly incorporating mechanistically reasonable chemistry of the vulcanization process.

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