Study of Methane Dehydroaromatization on Impregnated Mo/ZSM-5 Catalysts and Characterization of Nanostructured Molybdenum Phases and Carbonaceous Deposits

2007 ◽  
Vol 46 (12) ◽  
pp. 4063-4074 ◽  
Author(s):  
Ekaterina V. Matus ◽  
Ilyas Z. Ismagilov ◽  
Olga B. Sukhova ◽  
Vladimir I. Zaikovskii ◽  
Lidiya T. Tsikoza ◽  
...  
Keyword(s):  
Carbonaceous Deposits ◽  
Methane Dehydroaromatization

scholarly journals Characterization of Carbonaceous Deposits on an End-of-Life Engines for Effective Cleaning for Remanufacturing

2021 ◽  
Vol 13 (2) ◽  
pp. 950
Author(s):  
Xing Wang ◽  
Jianfeng Li ◽  
Xiujie Jia ◽  
Mingliang Ma ◽  
Yuan Ren
Keyword(s):  
End Of Life ◽  
Sustainable Manufacturing ◽  
Hybrid Structure ◽  
Nuclear Magnetic Resonance Study ◽  
Carbonaceous Deposit ◽  
X Ray ◽  
Cleaning Method ◽  
Carbonaceous Deposits ◽  
Strong Adhesion

Remanufacturing is one of the most effective strategies to achieve sustainable manufacturing and restore the performance of end-of-life products. However, the lack of an effective cleaning method to clean carbonaceous deposits severely hampers the remanufacturing of end-of-life engines. To explore an appropriate cleaning method, it is necessary to first study the characterization of the carbonaceous deposits. A broad range of analyses including X-ray fluorescence spectrometry, thermogravimetric analysis, 1H-nuclear magnetic resonance study, X-ray diffraction analysis, and scanning electron microscopy were performed to conduct an in-depth characterization of the carbonaceous deposits. The results showed that a hybrid structure composed of organics and inorganics is the most distinguishing feature of the carbonaceous deposit in end-of-life engines. The inorganics form the skeleton on which organics get attached, thereby resulting in a strong adhesion of the deposit and increasing the difficulty of cleaning. Therefore, a method in which several cleaning forces can be simultaneously applied is more suitable for the present purpose. Molten salt cleaning was chosen to verify the feasibility of this proposal. This method was shown to have the potential to effectively clean the carbonaceous deposit. This finding could contribute towards promoting the effective remanufacturing of end-of-life engines.

Thermal desorption and characterization of carbonaceous deposits in Mo/HZSM-5 catalyst

2019 ◽  
Vol 138 ◽  
pp. 22-28 ◽  
Author(s):  
Ganesh Sanapur ◽  
Arun Kumar ◽  
Amit Mondal ◽  
Sivakumar Sreeramagiri ◽  
Rajeshwer Dongara ◽  
...  
Keyword(s):  
Thermal Desorption ◽  
Carbonaceous Deposits

scholarly journals Deactivation and Regeneration of Mo/ZSM-5 Catalysts for Methane Dehydroaromatization

2009 ◽  
Vol 12 (1) ◽  
pp. 1 ◽  
Author(s):  
E.V. Matus ◽  
O.B. Sukhova ◽  
I.Z. Ismagilov ◽  
V.I. Zaikovskii ◽  
M.A. Kerzhentsev ◽  
...  
Keyword(s):  
Reaction Time ◽  
Reaction Temperature ◽  
Methane Conversion ◽  
Formation Rate ◽  
Space Velocity ◽  
Molybdenum Content ◽  
Stable Operation ◽  
Carbonaceous Deposits ◽  
Methane Dehydroaromatization ◽  
The Stability

The methane dehydroaromatization (DHA) was studied over a series of impregnated Mo/ZSM-5 catalysts with different molybdenum contents (1-10 wt.%). It was shown that total methane conversion was decreased by 30% during 12 h of DHA reaction. The benzene formation rate was increased from 0.5 to 13.9 mol C<sub>6</sub>H<sub>6</sub>/(g<sub>Mo</sub>·s) when the molybdenum content in the catalyst was lowered from 10 to 1 wt.%. The deactivated Mo/ZSM-5 catalysts were studied by a group of methods: N<sub>2</sub> adsorption, XRD, TGDTA, HRTEM and XPS. The content and condensation degree (C/H ratio) of the carbonaceous deposits was found to increase with an increase of either of the following parameters: molybdenum content (1-10 wt.%), reaction temperature (720-780 °C), space velocity (405-1620 h<sup>-1</sup>), reaction time (0.5-20 h). The stability of Mo/ZSM-5 catalysts in reaction-regeneration cycles was better when the time on stream was shorter. The regeneration conditions of deactivated Mo/ZSM-5 catalysts providing their stable operation under multiple reaction-regeneration cycles have been selected.

Activation of Ethylene C-H Bonds on Uniform D8 Ir(I) and Ni(II) Cations in Zeolites: Catalytic Butadiene and Butenes Production Under Mild Conditions

2019 ◽  
Author(s):  
Nicholas R. Jaegers ◽  
Konstantin Khivantsev ◽  
Libor Kovarik ◽  
Dan Klaus ◽  
Jian Zhi Hu ◽  
...  
Keyword(s):  
Molecular Level ◽  
Ambient Conditions ◽  
Reaction Conditions ◽  
Mild Conditions ◽  
Carbonaceous Deposits ◽  
Dehydrogenative Coupling ◽  
Ethylene Conversion ◽  
Active Metal ◽  
First Time

<div> <p>The homolytic activation of the strong C-H bonds in ethylene is demonstrated, for the first time, on d<sup>8</sup> Ir(I) and Ni(II) single atoms in the cationic positions of zeolites H-FAU and H-BEA under ambient conditions. The oxidative addition of C<sub>2</sub>H<sub>4</sub> to the metal center occurs with the formation of a Ir(III) and Ni(IV) vynil hydride, explaining the initiation of the Cossee-Arlman cycle on d<sup>8</sup> M(I/II) sites in the absence of pre-existing M-H bonds. Under mild reaction conditions (80-220ᵒC, 1 bar), the catalytic dimerization to butenes and the unprecedented dehydrogenative coupling of ethylene to butadiene occurs over these catalysts. Butene-1 is not converted to butadiene under the reaction conditions applied. Post-reaction characterization of the two materials reveals that the active metal cations remain site-isolated whereas deactivation occurs due to the formation of carbonaceous deposits on the zeolites. Our findings have significant implications for the molecular level understanding of ethylene conversion and the development of new ways to functionalize C-H bonds under mild conditions.</p> </div>

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