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

2017 ◽  
Vol 7 (2) ◽  
pp. 115 ◽  
Author(s):  
Z.R. Ismagilov ◽  
L.T. Tsikoza ◽  
E.V. Matus ◽  
G.S. Litvak ◽  
I.Z. Ismagilov ◽  
...  
Keyword(s):  
Methane Concentration ◽  
Stable Operation ◽  
Reaction Conditions ◽  
Catalyst Synthesis ◽  
Synthesis Conditions ◽  
Carbonaceous Deposits ◽  
Oxidative Treatment ◽  
Treatment Conditions ◽  
Methane Dehydroaromatization ◽  
Mo Content

<p>The character of carbonaceous deposits formed during methane dehydroaromatization reaction in the presence of Mo/ZSM-5 catalysts was studied by differential thermal analysis. The dependence of the concentration and condensation degree (C/H ratio) of the carbonaceous deposits on the catalyst synthesis conditions (Mo content = 1-10%, Si/Al ratio in the initial H-ZSM-5 = 17-45) and reaction conditions (feed flow rate = 405-1620 h<sup>-1</sup>, methane concentration = 90-98%, reaction temperature = 720-780 °C) was investigated. The oxidative treatment conditions of carbonized Mo/ZSM-5 catalysts providing stable operation of the catalysts under multiple reaction-oxidative treatment cycles were selected.</p>

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.

scholarly journals Synthesis and Application of Heterogeneous Catalysts Based on Heteropolyacids for 5-Hydroxymethylfurfural Production from Glucose

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 655 ◽  
Author(s):  
Jéssica Siqueira Mancilha Nogueira ◽  
João Paulo Alves Silva ◽  
Solange I. Mussatto ◽  
Livia Melo Carneiro
Keyword(s):  
Experimental Design ◽  
Heterogeneous Catalysts ◽  
Catalyst Concentration ◽  
Active Phase ◽  
Production Performance ◽  
Reaction Conditions ◽  
Catalyst Synthesis ◽  
Synthesis Conditions ◽  
Different Temperatures ◽  
Water Ratio

This study aimed to evaluate the synthesis and application of heterogeneous catalysts based on heteropolyacids for 5-hydroxymethylfurfural (HMF) production from glucose. Initially, assays were carried out in order to establish the most favorable catalyst synthesis conditions. For such purpose, calcination temperature (300 or 500 °C), type of support (Nb2O5 or Al2O3), and active phase (H3PW12O40—HPW or H3PMo12O40—HPMo) were tested and combined based on Taguchi’s L8 orthogonal array. As a result, HPW-Nb2O5 calcined at 300 °C was selected as it presented optimal HMF production performance (9.5% yield). Subsequently, the reaction conditions capable of maximizing HMF production from glucose using the selected catalyst were established. In these experiments, different temperatures (160 or 200 °C), acetone-to-water ratios (1:1 or 3:1 v/v), glucose concentrations (50 or 100 g/L), and catalyst concentrations (1 or 5% w/v) were evaluated according to a Taguchi’s L16 experimental design. The conditions that resulted in the highest HMF yield (40.8%) consisted of using 50 g/L of glucose at 160 °C, 1:1 (v/v) acetone-to-water ratio, and catalyst concentration of 5% (w/v). Recycling tests revealed that the catalyst can be used in four runs, which results in the same HMF yield (approx. 40%).

scholarly journals Catalytic Activity of High-Surface-Area Amorphous MgO Obtained from Upsalite

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1338
Author(s):  
Marek Gliński ◽  
Ewa M. Iwanek (nee Wilczkowska) ◽  
Urszula Ulkowska ◽  
Agnieszka Czajka ◽  
Zbigniew Kaszkur
Keyword(s):  
Surface Area ◽  
Carbonyl Compounds ◽  
Main Product ◽  
High Surface ◽  
High Surface Area ◽  
Hydrogenation Reaction ◽  
Transfer Hydrogenation ◽  
Reaction Conditions ◽  
Synthesis Conditions ◽  
Transfer Hydrogenation Reaction

The first aim of the research was to synthesize a pure Upsalite, which is an amorphous form of MgCO3, by modifying a procedure described in the literature, so that it would be the precursor of a high-surface, amorphous magnesium oxide. The results indicate that within the studied reaction conditions, the type of alcohol used as the reactant has the most pronounced effect on the yield of reaction. From the two alcohols that led to the highest yield of Upsalite, methanol gave a substantially larger surface area (794 vs. 191 m2 g−1). The optimized synthesis conditions of Upsalite were used to obtain MgO via thermolysis, whose activity in the transfer hydrogenation reaction (THR) from ethanol, 2-propanol and 2-pentanol to various carbonyl compounds was determined. The optimal conditions for the thermolysis were as follows: vacuum, T = 673 K as the final temperature, and a heating rate of 2 deg min−1. The high-surface, amorphous magnesia (SBET = 488 m2 g−1) was found to be a very selective catalyst to 4-t-butylcyclohexanone in THR, which led to a diastereoselectivity of over 94% to the E-isomer of 4-t-butylcyclohexanol for more than 3 h, with conversions of up to 97% with either 2-propanol or 2-pentanol as the hydrogen donor. In the case of acrolein and 2-n-propylacrolein being used as the hydrogen acceptors, the unsaturated alcohol (UOL) was the main product of the reaction, with higher UOL yields noted for ethanol than 2-propanol.

scholarly journals Structural Changes of Mo/ZSM-5 Catalysts During the Methane Dehydroaromatization

2009 ◽  
Vol 12 (1) ◽  
pp. 9 ◽  
Author(s):  
Z.R. Ismagilov ◽  
E.V. Matus ◽  
I.Z. Ismagilov ◽  
M.A. Kerzhentsev ◽  
V.I. Zailovskii ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Atomic Ratio ◽  
X Ray ◽  
Reducing Atmosphere ◽  
Structure Changes ◽  
Transmission Electron ◽  
Methane Dehydroaromatization ◽  
Naoh Treatment ◽  
Mo Content

<p>The structure changes of Mo/ZSM-5 catalysts with different Mo content (2 and 10 wt. % Mo) and Si/Al atomic ratio (17, 30 and 45) during the methane dehydroaromatization have been investigated by X-ray powder diffractometry, N<sub>2</sub> adsorption and transmission electron microscopy. The treatment of Mo/ZSM-5 catalysts in reducing atmosphere (CH<sub>4</sub> or H<sub>2</sub>) at about 700 °C promotes development of mesoporous system. The pores are open to the exterior of the zeolite grain and have an entrance diameter of ~ 4-10 nm. It is proposed that mesopore formation in Mo/ZSM-5 catalyst is connected with the dealumination of zeolite. The mesopore formation in the parent H-ZSM-5 zeolite by NaOH treatment does not improve the activity of /ZSM-5 catalyst.</p>

scholarly journals Synthesis of NdAlO3 Nanoparticles and Evaluation of the Catalytic Capacity for Biodiesel Synthesis

Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1545 ◽  
Author(s):  
Dionicio-Navarrete ◽  
Arrieta-Gonzalez ◽  
Quinto-Hernandez ◽  
Casales-Diaz ◽  
Zuñiga-Diaz ◽  
...  
Keyword(s):  
Mass Ratio ◽  
Reaction Products ◽  
Optimum Conditions ◽  
Reaction Conditions ◽  
Catalyst Synthesis ◽  
Synthesis Of Nanoparticles ◽  
Biodiesel Synthesis ◽  
Dta Analysis ◽  
Optimum Reaction ◽  
Catalytic Capacity

Biodiesel synthesis was carried out via heterogeneous catalysis of canola oil with nanoparticles of a mixed oxide based on rare earths. The catalyst synthesis (NdAlO3) was carried out based on the method proposed by Pechini for the synthesis of nanoparticles. Thermogravimetric analysis-differential thermal analysis (TGA-DTA) analysis was performed on the nanoparticle precursor gel in order to establish the optimum conditions for its calcination, with these being of 800 °C over 24 h. A pure NdAlO3 compound with an approximate size of 100 nm was obtained. The products of the transesterification reaction were analyzed using gas chromatography, FTIR, and NMR. The optimum reaction conditions were determined, namely, the temperature effect, reaction time, methanol:oil mass ratio, and recyclability of the catalyst. These studies showed the following optimal conditions: 200 °C, 5 h, methanol:oil mass ratio of 6:1, and a constant decrease in the catalytic activity of the catalyst was observed for up to six reuses, which later remained constant at around a 50% conversion rate. The maximum biodiesel yield obtained with the optimum conditions was around 75%. Analysis of the reaction products showed that the residual oil showed a chemical composition different from that of the source oil, and that both the biodiesel and glycerol obtained were of high purity.

scholarly journals Promoters for Improvement of the Catalyst Performance in Methane Valorization Processes

2021 ◽  
Vol 23 (3) ◽  
pp. 147
Author(s):  
I.Z. Ismagilov ◽  
A.V. Vosmerikov ◽  
L.L. Korobitsyna ◽  
E.V. Matus ◽  
M.A. Kerzhentsev ◽  
...  
Keyword(s):  
High Efficiency ◽  
Catalyst Activity ◽  
Operation Mode ◽  
Coke Formation ◽  
Product Yield ◽  
Carbon Accumulation ◽  
Stable Operation ◽  
Coke Content ◽  
Methane Dehydroaromatization ◽  
Long Time

In this work, the introduction of modifying additives in the composition of catalysts is considered as an effective mode of improving functional characteristics of materials for two processes of methane conversion into valuable products – methane dehydroaromatization (DHA of CH4) into benzene and hydrogen and autothermal reforming of methane (ATR of CH4) into synthesis gas. The effect of type and content of promoters on the structural and electronic state of the active component as well as catalyst activity and stability against deactivation is discussed. For DHA of CH4 the operation mode of additives M = Ag, Ni, Fe in the composition of Mo-M/ZSM-5 catalysts was elucidated and correlated with the product yield and coke content. It was shown that when Ag serves as a promoter, the duration of the catalyst stable operation is enhanced due to a decrease in the rate of the coke formation. In the case of Ni and Fe additives, the Ni-Мо and Fe-Mo alloys are formed that retain the catalytic activity for a long time in spite of the carbon accumulation. For ATR of CH4, the influence of M = Pd, Pt, Re, Mo, Sn in the composition of Ni-M catalysts supported on La2O3 or Ce0.5Zr0.5O2/Al2O3 was elucidated. It was demonstrated that for Ni-M/La2O3 catalysts, Pd is a more efficient promoter that improves the reducibility of Ni cations and increases the content of active Nio centers. In the case of Ni-M/Ce0.5Zr0.5O2/Al2O3 samples, Re is considered the best promoter due to the formation of an alloy with anti-coking and anti-sintering properties. The use of catalysts with optimal promoter type and its content provides high efficiency of methane valorization processes.

The Influence of Synthesis Parameters on FeO(OH) / Fe2O3 Formation by Hydrothermal Techniques

2010 ◽  
Vol 65 (8) ◽  
pp. 1024-1032 ◽  
Author(s):  
Madalina Popescu ◽  
Roxana Piticescu ◽  
Eugeniu Vasile ◽  
Dragos Taloi ◽  
Mirela Petriceanu ◽  
...  
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Iron Oxides ◽  
Hydrothermal Process ◽  
Single Step ◽  
Reaction Conditions ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis ◽  
Synthesis Conditions ◽  
Synthesis Parameters

In this paper, a hydrothermal method of high-pressure and low-temperature synthesis conditions is presented as a simple single-step technique to obtain crystalline nanoparticles of iron oxides. The aim of this work has been to demonstrate the influence of the main synthesis parameters on the formation of nanosized Fe2O3 particles using statistical methods and to establish the most significant effects. Based on mathematical pre-modeling calculations, the best reaction conditions for the hydrothermal process have been chosen, and controlled crystalline nanostructures of iron oxides could be prepared

scholarly journals Eco-Friendly and Sustainable Process for Converting Hydrous Bioethanol to Butanol

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 498
Author(s):  
Miron V. Landau ◽  
Tomy Hos ◽  
Roxana Vidruk Nehemya ◽  
George Nomikos ◽  
Moti Herskowitz
Keyword(s):  
Economic Analysis ◽  
Process Simulation ◽  
Space Velocity ◽  
Stable Operation ◽  
Reaction Conditions ◽  
Solid Catalysts ◽  
Theoretical Yield ◽  
Catalytic Processes ◽  
Hydrous Ethanol

The purpose of the study was the development of water-resistant catalyst and catalytic processes for the conversion of hydrous ethanol to 1-butanol. Water, in hydrous ethanol, strongly inhibits conversion to 1-butanol on solid catalysts. In this study, the nonstoichiometric P-deficient hydroxyapatite containing carbonate anions (C-HAP), Ca10−x/2(PO4)6−x(CO3)x(OH)2, displayed good performance in the Guerbet condensation of hydrated ethanol to 1-butanol, after proper stabilization of reaction conditions. Hydrous ethanol (96 wt%) was converted on C-HAP formed as extrudates with silica binder at 400 °C and weight hour space velocity (WHSV) = 0.5–1.0 h−1 to yield 21–23% 1-butanol and 73–74% selectivity. It displayed stable operation for up to 170 h on streams conducted in bench and mini-pilot rigs with catalyst loadings of 2 and 50 cm3, respectively. The process simulation employed the recycling of ethanol without laboratory verification to reach 68% theoretical yield of 1-butanol. The techno-economic analysis demonstrated the feasibility of this process, showing that it may be profitable depending on the prices of hydrated ethanol and 1-butanol.

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