A Comparison of the H3PW12O40/MCM-41 and HY Zeolite for Alkenylation of p-Xylene with Phenylacetylene

2013 ◽  
Vol 634-638 ◽  
pp. 377-381 ◽  
Author(s):  
Zhong Kui Zhao ◽  
Yi Tao Dai
Keyword(s):  
Flow Reactor ◽  
Fixed Bed ◽  
Catalytic Performance ◽  
Hy Zeolite ◽  
Ultrasonic Assisted ◽  
Acidic Sites ◽  
High Dispersity ◽  
Catalytic Stability ◽  
Temperature Programmed ◽  
Mcm 41

The initial activity, selectivity, and especially catalytic stability of mesoporous MCM-41 supported phosphotungstic acid (HPW) prepared by ultrasonic-assisted impregnation (UAI) method and the HY zeolite were contrastively investigated for alkenylation of p-xylene with phenylacetylene in a fixed-bed continuous flow reactor. N2 adsorption-desorption, FT-IR, X-ray diffraction (XRD) and NH3 temperature-programmed (NH3-TPD) desorption characterization techniques were employed to explore the relationship of catalyst nature and catalytic performance in alkenylation. Results illustrate that the as-prepared HPW/MCM-41 catalyst exhibits notably superior catalytic activity, selectivity and stability to microporous HY zeolite, ascribed to its well-ordered mesoporous architecture, appropriate acidic sites and high dispersity of HPW phase.

scholarly journals The Effect of Mg and Zn Dopants on Pt/Al2O3 for the Dehydrogenation of Perhydrodibenzyltoluene

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 490
Author(s):  
Rudaviro Garidzirai ◽  
Phillimon Modisha ◽  
Innocent Shuro ◽  
Jacobus Visagie ◽  
Pieter van Helden ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Inductively Coupled Plasma ◽  
Flow Reactor ◽  
Plug Flow ◽  
Optical Emission ◽  
Catalytic Performance ◽  
Emission Spectrometry ◽  
Hydrogen Yield ◽  
X Ray ◽  
Temperature Programmed

The effects of Mg and Zn dopants on the catalytic performance of Pt/Al2O3 catalyst were investigated for dehydrogenation of perhydrodibenzyltoluene (H18-DBT) as a liquid organic hydrogen carrier. Al2O3 supports were modified with Mg and Zn to produce Mg-Al2O3 and Zn-Al2O3 with a target loading of 3.8 wt.% for dopants. The modified supports were impregnated with chloroplatinic acid solution to produce the catalysts Pt/Al2O3, Pt/Mg-Al2O3 and Pt/Zn-Al2O3 of 0.5 wt.% Pt loading. Thereafter, the catalysts were characterised using inductively coupled plasma- optical emission spectrometry, scanning electron microscopy-energy dispersive X-ray spectroscopy, hydrogen temperature-programmed reduction, carbon-monoxide pulse chemisorption, ammonia temperature-programmed desorption, X-ray diffraction and transmission electron microscopy. The dehydrogenation experiments were performed using a horizontal plug flow reactor system and the catalyst time-on-stream was 22 h. Pt/Mg-Al2O3 showed the highest average hydrogen flowrate of 29 nL/h, while an average of 27 nL/h was obtained for both Pt/Al2O3 and Pt/Zn-Al2O3. This has resulted in a hydrogen yield of 80% for Pt/Mg-Al2O3, 71% for Pt/Zn-Al2O3 and 73% for Pt/Al2O3. In addition, the conversion of H18-DBT ranges from 99% to 92%, Pt 97–90% and 96–90% for Pt/Mg-Al2O3, Pt/Zn-Al2O3 and Pt/Al2O3, respectively. Following the latter catalyst order, the selectivity to dibenzyltoluene (H0-DBT) ranges from 78% to 57%, 75–51% and 71–45%. Therefore, Pt/Mg-Al2O3 showed improved catalytic performance towards dehydrogenation of H18-DBT.

The Effects of Preparation Methods on Iron Structures of Iron-Supported HZSM-5 and their Catalytic Performance for Methanol Dehydration

2016 ◽  
Vol 723 ◽  
pp. 633-639
Author(s):  
Waenkaew Pantupho ◽  
Arthit Neramittagapong ◽  
Nuttawut Osakoo ◽  
Jatuporn Wittayakun ◽  
Sirinuch Loiha
Keyword(s):  
Flow Reactor ◽  
Fixed Bed ◽  
Catalytic Performance ◽  
Active Species ◽  
Iron Complex ◽  
Methanol Dehydration ◽  
Low Carbon ◽  
Zeolite Framework ◽  
Preparation Methods ◽  
Binuclear Iron

Iron-supported HZSM-5 catalysts were prepared by hydrothermal (Fe-HZSM-5_HYD) and impregnation methods (Fe/HZSM-5_IMP). The active species of binuclear-iron complex and iron-substituted zeolite framework, confirmed by EXAFS analysis, were observed on Fe/HZSM-5_IMP and Fe-HZSM-5_HYD, respectively. The catalysts were used for production of dimethyl ether (DME) by methanol dehydration at 200-350 °C using fixed bed flow reactor. Fe/HZSM-5_IMP showed higher catalytic conversion than Fe-HZSM-5_HYD. However, the Fe/HZSM-5_IMP catalyst was less selective to DME product and strongly deactivated for 24h. The deactivation might due to transformation of binuclear-iron to the a-iron site which was strong acidic strengh. The iron-substituted zeolite framework of Fe-HZSM-5_HYD showed high stability toward methanol dehydration. Moreover, the catalyst showed advantages of good selective to DME and low carbon deposition on surface. These results suggested that the iron-substituted zeolite framework structure could improve catalytic performance for mrthanol dehydration.

scholarly journals Comparison of Two Preparation Methods on Catalytic Activity and Selectivity of Ru-Mo/HZSM5 for Methane Dehydroaromatization

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Lucia M. Petkovic ◽  
Daniel M. Ginosar
Keyword(s):  
Molybdenum Carbide ◽  
Molybdenum Trioxide ◽  
Catalyst Activity ◽  
Catalytic Performance ◽  
Preparation Methods ◽  
Ammonium Heptamolybdate ◽  
Temperature Programmed Oxidation ◽  
Methane Dehydroaromatization ◽  
Acidic Sites ◽  
Temperature Programmed

Catalytic performance of Mo/HZSM5 and Ru-Mo/HZSM5 catalysts prepared by vaporization-deposition of molybdenum trioxide and impregnation with ammonium heptamolybdate was analyzed in terms of catalyst activity and selectivity, nitrogen physisorption analyses, temperature-programmed oxidation of carbonaceous residues, and temperature-programmed reduction. Vaporization-deposition rendered the catalyst more selective to ethylene and coke than the catalyst prepared by impregnation. This result was assigned to lower interaction of molybdenum carbide with the zeolite acidic sites.

scholarly journals Catalytic Performance of Spherical MCM-41 Modified with Copper and Iron as Catalysts of NH3-SCR Process

Molecules ◽  
2020 ◽  
Vol 25 (23) ◽  
pp. 5651
Author(s):  
Aleksandra Jankowska ◽  
Agata Chłopek ◽  
Andrzej Kowalczyk ◽  
Małgorzata Rutkowska ◽  
Marek Michalik ◽  
...  
Keyword(s):  
Ammonia Oxidation ◽  
Surface Acidity ◽  
Catalytic Performance ◽  
Emission Spectrometry ◽  
High Catalytic Activity ◽  
Reaction Products ◽  
Nh3 Scr ◽  
Vis Spectroscopy ◽  
Temperature Programmed ◽  
Mcm 41

Spherical MCM-41 with various copper and iron loadings was prepared by surfactant directed co-condensation method. The obtained samples were characterized with respect to their structure (X-ray diffraction, XRD), texture (N2 sorption), morphology (scanning electron microscopy, SEM), chemical composition (inductively coupled plasma optical emission spectrometry, ICP-OES), surface acidity (temperature programmed desorption of ammonia, NH3-TPD), form, and aggregation of iron and copper species (diffuse reflectance UV-Vis spectroscopy, UV-Vis DRS) as well as their reducibility (temperature programmed reduction with hydrogen, H2-TPR). The spherical MCM-41 samples modified with transition metals were tested as catalysts of selective catalytic reduction of NO with ammonia (NH3-SCR). Copper containing catalysts presented high catalytic activity at low-temperature NH3-SCR with a very high selectivity to nitrogen, which is desired reaction products. Similar results were obtained for iron containing catalysts, however in this case the loadings and forms of iron incorporated into silica samples very strongly influenced catalytic performance of the studied samples. The efficiency of the NH3-SCR process at higher temperatures was significantly limited by the side reaction of direct ammonia oxidation. The reactivity of ammonia molecules chemisorbed on the catalysts surface in NO reduction (NH3-SCR) and their selective oxidation (NH3-SCO) was verified by temperature-programmed surface reactions.

Hydrogenation of Model Compounds Catalyzed by MCM-41-Supported Nickel Phosphide

2013 ◽  
Vol 864-867 ◽  
pp. 366-372 ◽  
Author(s):  
Liang Yan Xia ◽  
Zhi Xiang Xia ◽  
Wei Tang ◽  
Hong Yan Wang ◽  
Meng Xiang Fang
Keyword(s):  
Catalyst Activity ◽  
Fixed Bed ◽  
Volume Ratio ◽  
Space Velocity ◽  
Fixed Bed Reactor ◽  
Nickel Phosphide ◽  
Great Performance ◽  
Different Temperatures ◽  
Temperature Programmed ◽  
Mcm 41

MCM-41 supported nickel phosphide (Ni2P/MCM-41) was prepared by temperature-programmed reduction of the corresponding phosphate. The catalyst activity for hydrodeoxygenation (HDO), hydrodearomatization (HDA), hydrodenitrogenation (HDN) and hydrodesulfurization (HDS) was investigated in a fixed bed reactor. O-cresol HDO, 1-methylnaphthalene HDA, quinoline HDN, dibenzothiophene HDS and simultaneous HDO, HDA, HDN, HDS were respectively tested at different temperatures with constant pressure (6.0 MPa), liquid hourly space velocity (3.0 h-1), hydrogen-to-oil volume ratio (600:1). The results indicate that Ni2P /MCM-41 catalyst has great performance on HDO, HDA, HDN, HDS in single model compound reactions. O-cresol and DBT are almost completely transformed at 375°C, while 1-methylnaphthalene and quinoline reach the highest conversion at 300°C. In the simultaneous reactions, quinoline shows higher conversion by competitive adsorption on the catalyst hydrogenation sites, leading to conversion decrease of o-cresol, 1-methylnaphthalene and DBT.

Preparation and Catalytic Performance of Ce-Y-Palygorskite Catalysts for NO Decomposition

2011 ◽  
Vol 197-198 ◽  
pp. 874-877
Author(s):  
Jian Guo Zou ◽  
Ping Luo ◽  
Yan Yan Liu ◽  
Hai Long Peng
Keyword(s):  
Flow Reactor ◽  
Ph Value ◽  
Fixed Bed ◽  
Catalytic Performance ◽  
Treatment Temperature ◽  
No Decomposition ◽  
Preparation Conditions ◽  
Blending Method ◽  
Denitration Rate ◽  
Catalysts Preparation

Ce-Y-palygorskite catalysts were prepared by chemical blending method. The effect of preparation conditions on catalytic performance of Ce-Y-palygorskite catalyst for NO decomposition was investigated in a fixed bed flow reactor. The characteristics of the Ce-Y-palygorskite catalysts were studied by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The obtained results provided substantial evidence that the catalysts preparation conditions would have strong effect on the catalytic activity for NO decomposition. The Ce-Y-palygorskite catalyst prepared under the optimal conditions: rare earth content, Ce/Y, pH value of the chemical blending and calcination treatment temperature was 3%, CexY(1-x)(x=0.9), 7 and 350°C, respectively, was identified as the most active catalyst for the NO decomposition, and the denitration rate could be up to 67.3% under the experimental reaction conditions.

An efficient Fe2O3/HY catalyst for Friedel–Crafts acylation of m-xylene with benzoyl chloride

RSC Advances ◽  
2014 ◽  
Vol 4 (70) ◽  
pp. 36951-36958 ◽  
Author(s):  
Manman Mu ◽  
Ligong Chen ◽  
Yunlong Liu ◽  
Wangwang Fang ◽  
Yang Li
Keyword(s):  
Catalytic Activity ◽  
Iron Oxide ◽  
Benzoyl Chloride ◽  
Catalytic Performance ◽  
Reaction Parameters ◽  
Hy Zeolite ◽  
Lewis Acidic Sites ◽  
Acidic Sites ◽  
Excellent Catalytic Performance

Iron oxide supported on HY zeolite was prepared and exhibited excellent catalytic performance in the acylation of m-xylene with benzoyl chloride. It was characterized by XRD, BET, XPS, NH3-TPD and Py-IR. The catalytic activity of Fe2O3/HY is enhanced with the increase of Lewis acidic sites. Furthermore, the reaction parameters were optimized. Finally, the catalyst was easily separated reused for five runs without appreciable loss of catalytic activity.

Effects of Microwave and Ultrasonic-Assisted Aging on the Synthesis of H-ZSM-5 Nanozeolite and Its Catalytic Performance in Methanol Dehydration

2014 ◽  
Vol 12 (1) ◽  
pp. 355-362 ◽  
Author(s):  
Saeid Abbasian ◽  
Majid Taghizadeh
Keyword(s):  
Fixed Bed ◽  
Catalytic Performance ◽  
Operating Conditions ◽  
Fixed Bed Reactor ◽  
Crystallization Time ◽  
Microwave Assisted ◽  
Ultrasonic Assisted ◽  
Ft Ir ◽  
Static Conditions ◽  
Ultrasonic Stirring

Abstract H-ZSM-5 nanozeolite was hydrothermally synthesized under static conditions. Evaluation of hydrothermal synthesis of ZSM-5 was performed by treating the synthesis mixture using different aging processes, consist of ultrasonic, stirring, and microwave-assisted aging, prior to the conventional hydrothermal treatment. The catalytic performances of selected catalysts were studied for the dehydration of methanol to dimethyl ether (DME) in a fixed-bed reactor under the same operating conditions (T = 300°C, P = 1 atm, and WHSV = 26 h−1). The prepared samples were characterized by XRD, SEM, BET, NH3-TPD and FT-IR techniques. The results showed that ultrasonic and microwave-assisted aging shortened the crystallization time and reduced crystal size of the obtained products without having any considerable effects on their catalytic activities.

scholarly journals Ru/Ce/Ni Metal Foams as Structured Catalysts for the Methanation of CO2

Catalysts ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 13
Author(s):  
Stefano Cimino ◽  
Elisabetta Maria Cepollaro ◽  
Luciana Lisi ◽  
Stefano Fasolin ◽  
Marco Musiani ◽  
...  
Keyword(s):  
Catalyst Deactivation ◽  
Flow Reactor ◽  
Fixed Bed ◽  
Large Temperature ◽  
Ni Foam ◽  
Co2 Methanation ◽  
Hydrogenation Of Co2 ◽  
Structured Catalysts ◽  
Temperature Programmed ◽  
Methanation Activity

The development of highly conductive structured catalysts with enhanced mass- and heat-transfer features is required for the intensification of the strongly exothermic catalytic hydrogenation of CO2 in which large temperature gradients should be avoided to prevent catalyst deactivation and to control selectivity. Therefore, in this work we set out to investigate the preparation of novel structured catalysts obtained from a commercial open cell Ni foam with high pore density (75 ppi) onto which a CeO2 layer was deposited via electroprecipitation, and, eventually, Ru was added by impregnation. Composite Ru/Ce/Ni foam catalysts, as well as simpler binary Ru/Ni and Ce/Ni catalysts were characterized by SEM-EDX, XRD, cyclic voltammetry, N2 physisorption, H2-temperature programmed reduction (TPR), and their CO2 methanation activity was assessed at atmospheric pressure in a fixed bed flow reactor via temperature programmed tests in the range from 200 to 450 °C. Thin porous CeO2 layers, uniformly deposited on the struts of the Ni foams, produced active catalytic sites for the hydrogenation of CO2 at the interface between the metal and the oxide. The methanation activity was further boosted by the dispersion of Ru within the pores of the CeO2 layer, whereas the direct deposition of Ru on Ni, by either impregnation or pulsed electrodeposition methods, was much less effective.

scholarly journals Direct Hydroxylation of Phenol to Dihydroxybenzenes by H2O2 and Fe-based Metal-Organic Framework Catalyst at Room Temperature

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 172 ◽  
Author(s):  
Alma D. Salazar-Aguilar ◽  
Gonzalo Vega ◽  
Jose A. Casas ◽  
Sofía Magdalena Vega-Díaz ◽  
Ferdinando Tristan ◽  
...  
Keyword(s):  
Room Temperature ◽  
Flow Reactor ◽  
Metal Organic Framework ◽  
Fixed Bed ◽  
Catalytic Performance ◽  
Solvent Free Conditions ◽  
Metal Organic ◽  
Direct Hydroxylation ◽  
Organic Framework

A semi-crystalline iron-based metal-organic framework (MOF), in particular Fe-BTC, that contained 20 wt.% Fe, was sustainably synthesized at room temperature and extensively characterized. Fe-BTC nanopowders could be used as an efficient heterogeneous catalyst for the synthesis of dihydroxybenzenes (DHBZ), from phenol with hydrogen peroxide (H2O2), as oxidant under organic solvent-free conditions. The influence of the reaction temperature, H2O2 concentration and catalyst dose were studied in the hydroxylation performance of phenol and MOF stability. Fe-BTC was active and stable (with negligible Fe leaching) at room conditions. By using intermittent dosing of H2O2, the catalytic performance resulted in a high DHBZ selectivity (65%) and yield (35%), higher than those obtained for other Fe-based MOFs that typically require reaction temperatures above 70 °C. The long-term experiments in a fixed-bed flow reactor demonstrated good Fe-BTC durability at the above conditions.

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