Investigation of the effect of VOx/ZrO2 structure on the catalytic activity in cyclohexene epoxidation

RSC Advances ◽  
2016 ◽  
Vol 6 (111) ◽  
pp. 110375-110382 ◽  
Author(s):  
Sanaa El-Korso ◽  
Sumeya Bedrane ◽  
Abderrahim Choukchou-Braham ◽  
Redouane Bachir
Keyword(s):  
Solid Solution ◽  
Catalytic Activity ◽  
Catalytic Performance ◽  
Cyclohexene Epoxidation ◽  
Vanadium Species ◽  
Cyclohexene Conversion

The coexistence of a solid solution with polymeric vanadium species in the case of 5VZr-2 and with the formation of ZrV2O7 in the case of 5VZr-3, resulted in good catalytic performance, with up to 80% epoxide selectivity and 32% cyclohexene conversion.

Direct Synthesis of DMC from CO2 and CH3OH over CexZr 1-x-0.1Y 0.1 O2 Catalysts

2011 ◽  
Vol 287-290 ◽  
pp. 1632-1635 ◽  
Author(s):  
Zhi Fang Zhang ◽  
Rui Bing Wang ◽  
Xiang Rong Ma
Keyword(s):  
Solid Solution ◽  
Catalytic Activity ◽  
Solid Solutions ◽  
Dimethyl Carbonate ◽  
Direct Synthesis ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Solid Solution Series ◽  
Calcination Temperatures ◽  
Bimodal Pore Structure

The solid solution series CexZr(1-x-0.1)Y0.1O2 with various x values was prepared by the citric acid sol-gel method, using cerium and zirconium nitrides as precursors, respectively.The characterization results of the XRD, N2 sorption measurements indicated that the physical properties of the solid solutions were significantly affected by the x values in CexZr(1-x-0.1)Y0.1O2 and the calcination temperatures. These solid solutions can be used as catalyst for the direct synthesis of dimethyl carbonate from CH3OH and CO2. Results indicated that the catalytic activity for DMC synthesis was influenced by the structure of the solid solutions and the x values in CexZr(1-x-0.1)Y0.1O2. The optimized Ce0.5Zr0.4Y0.1O2 with bimodal pore structure exhibited higher catalytic performance to DMC synthesis.

The design and catalytic performance of molybdenum active sites on an MCM-41 framework for the aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

2019 ◽  
Vol 9 (3) ◽  
pp. 811-821 ◽  
Author(s):  
Zhao-Meng Wang ◽  
Li-Juan Liu ◽  
Bo Xiang ◽  
Yue Wang ◽  
Ya-Jing Lyu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Aerobic Oxidation ◽  
Catalytic Performance ◽  
Mcm 41

The catalytic activity decreases as –(SiO)3Mo(OH)(O) > –(SiO)2Mo(O)2 > –(O)4–MoO.

scholarly journals Influence of the Reduction Temperature and the Nature of the Support on the Performance of Zirconia and Alumina-Supported Pt Catalysts for n-Dodecane Hydroisomerization

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 88
Author(s):  
Diana García-Pérez ◽  
Maria Consuelo Alvarez-Galvan ◽  
Jose M. Campos-Martin ◽  
Jose L. G. Fierro
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
Catalytic Properties ◽  
Catalytic Performance ◽  
Major Influence ◽  
Pt Catalysts ◽  
Reduction Temperature ◽  
Metal Dispersion ◽  
Tungsten Oxides ◽  
Supported Pt Catalysts

Catalysts based on zirconia- and alumina-supported tungsten oxides (15 wt % W) with a small loading of platinum (0.3 wt % Pt) were selected to study the influence of the reduction temperature and the nature of the support on the hydroisomerization of n-dodecane. The reduction temperature has a major influence on metal dispersion, which impacts the catalytic activity. In addition, alumina and zirconia supports show different catalytic properties (mainly acid site strength and surface area), which play an important role in the conversion. The NH3-TPD profiles indicate that the acidity in alumina-based catalysts is clearly higher than that in their zirconia counterparts; this acidity can be attributed to a stronger interaction of the WOx species with alumina. The PtW/Al catalyst was found to exhibit the best catalytic performance for the hydroisomerization of n-dodecane based on its higher acidity, which was ascribed to its larger surface area relative to that of its zirconia counterparts. The selectivity for different hydrocarbons (C7–10, C11 and i-C12) was very similar for all the catalysts studied, with branched C12 hydrocarbons being the main products obtained (~80%). The temperature of 350 °C was clearly the best reduction temperature for all the catalysts studied in a trickled-bed-mode reactor.

scholarly journals A diffusion anisotropy descriptor links morphology effects of H-ZSM-5 zeolites to their catalytic cracking performance

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Xiaoliang Liu ◽  
Jing Shi ◽  
Guang Yang ◽  
Jian Zhou ◽  
Chuanming Wang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Catalytic Cracking ◽  
Catalytic Performance ◽  
Zeolite Catalysts ◽  
Time Resolved ◽  
Cracking Performance ◽  
Morphology Effect ◽  
Ft Ir ◽  
The Difference ◽  
Dynamics Simulations

AbstractZeolite morphology is crucial in determining their catalytic activity, selectivity and stability, but quantitative descriptors of such a morphology effect are challenging to define. Here we introduce a descriptor that accounts for the morphology effect in the catalytic performances of H-ZSM-5 zeolite for C4 olefin catalytic cracking. A series of H-ZSM-5 zeolites with similar sheet-like morphology but different c-axis lengths were synthesized. We found that the catalytic activity and stability is improved in samples with longer c-axis. Combining time-resolved in-situ FT-IR spectroscopy with molecular dynamics simulations, we show that the difference in catalytic performance can be attributed to the anisotropy of the intracrystalline diffusive propensity of the olefins in different channels. Our descriptor offers mechanistic insight for the design of highly effective zeolite catalysts for olefin cracking.

scholarly journals Performance Analysis of TiO2-Modified Co/MgAl2O4 Catalyst for Dry Reforming of Methane in a Fixed Bed Reactor for Syngas (H2, CO) Production

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3347
Author(s):  
Arslan Mazhar ◽  
Asif Hussain Khoja ◽  
Abul Kalam Azad ◽  
Faisal Mushtaq ◽  
Salman Raza Naqvi ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Fixed Bed ◽  
Catalytic Performance ◽  
Dry Reforming ◽  
Fixed Bed Reactor ◽  
Dry Reforming Of Methane ◽  
Catalyst Stability ◽  
Feed Ratio ◽  
Catalyst Loading ◽  
Impregnation Method

Co/TiO2–MgAl2O4 was investigated in a fixed bed reactor for the dry reforming of methane (DRM) process. Co/TiO2–MgAl2O4 was prepared by modified co-precipitation, followed by the hydrothermal method. The active metal Co was loaded via the wetness impregnation method. The prepared catalyst was characterized by XRD, SEM, TGA, and FTIR. The performance of Co/TiO2–MgAl2O4 for the DRM process was investigated in a reactor with a temperature of 750 °C, a feed ratio (CO2/CH4) of 1, a catalyst loading of 0.5 g, and a feed flow rate of 20 mL min−1. The effect of support interaction with metal and the composite were studied for catalytic activity, the composite showing significantly improved results. Moreover, among the tested Co loadings, 5 wt% Co over the TiO2–MgAl2O4 composite shows the best catalytic performance. The 5%Co/TiO2–MgAl2O4 improved the CH4 and CO2 conversion by up to 70% and 80%, respectively, while the selectivity of H2 and CO improved to 43% and 46.5%, respectively. The achieved H2/CO ratio of 0.9 was due to the excess amount of CO produced because of the higher conversion rate of CO2 and the surface carbon reaction with oxygen species. Furthermore, in a time on stream (TOS) test, the catalyst exhibited 75 h of stability with significant catalytic activity. Catalyst potential lies in catalyst stability and performance results, thus encouraging the further investigation and use of the catalyst for the long-run DRM process.

Three-dimensionally ordered macroporous spinel-type MCr2O4 (M = Co, Ni, Zn, Mn) catalysts with highly enhanced catalytic performance for soot combustion

2015 ◽  
Vol 5 (9) ◽  
pp. 4594-4601 ◽  
Author(s):  
Jinguo Wang ◽  
Gaoyang Yang ◽  
Li Cheng ◽  
Eun Woo Shin ◽  
Yong Men
Keyword(s):  
Catalytic Activity ◽  
Three Dimensional ◽  
Catalytic Performance ◽  
Soot Combustion ◽  
Spinel Type ◽  
Ordered Macroporous

MCr2O4 catalysts with three-dimensional ordered macroporous structures displayed superior catalytic activity for soot combustion to their bulk counterparts.

scholarly journals On the Effects of Doping on the Catalytic Performance of (La,Sr)CoO3. A DFT Study of CO Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 312 ◽  
Author(s):  
Antonella Glisenti ◽  
Andrea Vittadini
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
Catalytic Performance ◽  
Energy Profiles ◽  
High Concentrations ◽  
3D Impurities

The effects of modifying the composition of LaCoO3 on the catalytic activity are predicted by density functional calculations. Partially replacing La by Sr ions has benefical effects, causing a lowering of the formation energy of O vacancies. In contrast to that, doping at the Co site is less effective, as only 3d impurities heavier than Co are able to stabilize vacancies at high concentrations. The comparison of the energy profiles for CO oxidation of undoped and of Ni-, Cu-m and Zn-doped (La,Sr)CoO3(100) surface shows that Cu is most effective. However, the effects are less spectacular than in the SrTiO3 case, due to the different energetics for the formation of oxygen vacancies in the two hosts.

The Synthesis of Iron Oxides with Different Phases or Exposure Crystal Planes and their Catalytic Property for Propene Oxidation

2012 ◽  
Vol 463-464 ◽  
pp. 189-193
Author(s):  
Kong Zhai Li ◽  
Masaaki Haneda ◽  
Masakuni Ozawa
Keyword(s):  
Catalytic Activity ◽  
Iron Oxides ◽  
Catalytic Property ◽  
Significant Influence ◽  
Catalytic Performance ◽  
Selective Growth ◽  
Crystal Plane ◽  
Low Density ◽  
Fe2o3 Nanoparticles ◽  
Propene Oxidation

Maghemite (γ-FeSubscript text2OSubscript text3) and hematite (α-Fe2O3) nanoparticles with various dominant exposure crystal planes were prepared by several different methods. The structure and the reducibility of these materials were investigated by XRD, Raman and H2-TPR technologies, and their catalytic performance for propene oxidation was also discussed. The maghemite (γ-FeSubscript text2OSubscript text3) showed a better reducibility than hematite (α-FeSubscript text2OSubscript text3), but its activity for propene oxidation is relatively lower. The exposure crystal plane of hematite has a significant influence on its catalytic activity for propene oxidation. Among the prepared four samples, the hematite-1 sample showed the best activity. The selective growth of any planes with a relative low density of Fe atoms for the α-FeSubscript text2OSubscript text3 catalyst would lead to an obvious decrease in the catalytic activity.

scholarly journals High-efficiency catalytic performance over mesoporous Ni/beta zeolite for the synthesis of quinoline from glycerol and aniline

RSC Advances ◽  
2017 ◽  
Vol 7 (16) ◽  
pp. 9551-9561 ◽  
Author(s):  
An Li ◽  
Chen Huang ◽  
Cai-Wu Luo ◽  
Wen-Jun Yi ◽  
Zi-Sheng Chao
Keyword(s):  
Catalytic Activity ◽  
Vapor Phase ◽  
High Efficiency ◽  
Zeolite Catalyst ◽  
Catalytic Performance ◽  
Beta Zeolite ◽  
Phase Process

Quinoline was synthesized via the typical Skraup approach with a vapor-phase process. The mesoporous Ni/beta zeolite catalyst exhibited high-efficiency catalytic activity and an enhanced ability of anti-deactivation.

A mesoporous “shell-in-shell” structured nanocatalyst with large surface area, enhanced synergy, and improved catalytic performance for Suzuki–Miyaura coupling reaction

2014 ◽  
Vol 50 (82) ◽  
pp. 12356-12359 ◽  
Author(s):  
Baocang Liu ◽  
Yuefang Niu ◽  
Yan Li ◽  
Fan Yang ◽  
Jiamin Guo ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
Coupling Reaction ◽  
Catalytic Performance ◽  
Large Surface Area ◽  
Mesoporous Shell

A novel mesoporous “shell-in-shell” structured nanoreactor (@Pd/meso-TiO2/Pd@meso-SiO2) shows superior catalytic activity, stability, and selectivity for Suzuki–Miyaura coupling reaction.

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