نتایج جستجو برای: vpo catalyst
تعداد نتایج: 44094 فیلتر نتایج به سال:
PtRu catalyst is a promising anodic catalyst for direct methanol fuel cells (DMFCs) but the slow reaction kinetics reduce the performance of DMFCs. Therefore, this study attempts to improve the performance of PtRu catalysts by adding nickel (Ni) and iron (Fe). Multiwalled carbon nanotubes (MWCNTs) are used to increase the active area of the catalyst and to improve the catalyst performance. Elec...
Fenton oxidation, an advanced oxidation process, is an efficient method for the treatment of recalcitrant wastewaters. Unfortunately, it utilizes H2O2 and iron-based homogeneous catalysts, which lead to the formation of high volumes of sludge and secondary pollutants. To overcome these problems, an alternate option is the usage of heterogeneous catalyst. In this study, a heterogeneous catalyst ...
The transition states in kinetic processes are often experimentally elusive. Computational tools can be used to gain an atomistic perspective into these transition states. A learning tool to guide students through the complexities of the theory while gaining an appreciation for the coupling of thermodynamic and kinetic processes is explored here. A computational protocol which hinges on combini...
In 1981 Pecoraro and Chianelli reported a complete study of catalytic behavior of transition metal sulfides catalysts in hydrodesulfurization (HDS) of dibenzothiophene (DBT) [1], in which was found a periodic tendency of the metallic sulfides activity, where ruthenium sulfide showed the highest HDS activity. These results were corroborated later by Raje et al. [2] and Liaw et al. [3], further s...
Particulate Matter (PM) is one of the major harmful substances in diesel exhaust gas. Technologies like the Diesel Particulate Filter (DPF) and Diesel Oxidation Catalyst (DOC) have been positioned at the exhaust to reduce the quantity of harmful substances released to the environment. This paper highlights the factors that affect combustion in diesel engines and the potential of the introductio...
Frequently the activity of fresh catalyst changes with time in use. The decrease or increases of the catalyst activity with time during the course of reaction forces the system to an unsteady state operation ([1], [2], [3], [4] and [5]). One of these catalysts is the copper/zinc oxide catalyst, which is industrially used for methanol production. The activity of copper/zinc oxide catalyst declin...
Deprotection of various phenols from their respective methoxymethyl ethers using an heteropolyacid catalyst was studied. The catalyst was the Wells-Dawson heteropolyacid, used both in bulk or supported on silica. Yields were high to quantitative after less than one hour reaction time and the catalyst was easily recoverable and reusable.
The lifetime (200 h) of a Cu/SiO(2) catalyst under DMO-ethanol feedstock is 20 times longer than that (10 h) of the catalyst under DMO-methanol feedstock without any modification of the catalyst. The stabilization effect of ethanol on the active centers can effectively slow down the agglomeration of copper particles during the hydrogenation process.
Attempts are made to define the “ideal synthesis”, “ideal catalyst”, and “ideal recoverable catalyst”. Although these unattainable limits can never be realized, they help to focus attention on attributes chemists should strive for. Criteria for evaluating catalyst recovery are analyzed, and increased attention to the critical and constructive evaluation of competing “green” chemical technologie...
The vital role of ethylenediaminetetraacetic acid on the structure and the oxygen reduction reaction activity of the non-precious-metal-based pyrolyzed catalyst is reported and elaborated. The resultant catalyst can overtake the performance of commercial Pt/C catalyst in an alkaline medium.
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