scholarly journals Effect of Phosphorus Modification on the Acidity, Nanostructure of the Active Phase, and Catalytic Performance of Residue Hydrodenitrogenation Catalysts

ACS Omega ◽  
2020 ◽  
Vol 5 (30) ◽  
pp. 19111-19119
Author(s):  
Ruiyu Zhao ◽  
Pingjuan Lu ◽  
Yuansheng Zhao ◽  
Longli Zhang ◽  
Yusheng Zhao ◽  
...  
Keyword(s):  
Active Phase ◽  
Catalytic Performance ◽  
Phosphorus Modification

scholarly journals CO-PROX Reaction over Co3O4|Al2O3 Catalysts—Impact of the Spinel Active Phase Faceting on the Catalytic Performance

2019 ◽  
Vol 123 (33) ◽  
pp. 20221-20232 ◽  
Author(s):  
Gabriela Grzybek ◽  
Klaudia Ciura ◽  
Joanna Gryboś ◽  
Paulina Indyka ◽  
Arantxa Davó-Quiñonero ◽  
...  
Keyword(s):  
Active Phase ◽  
Catalytic Performance

scholarly journals Highly Active Trifloaluminate Ionic Liquids as Recyclable Catalysts for Green Oxidation of 2,3,6-Trimethylphenol to Trimethyl-1,4-Benzoquinone

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1469
Author(s):  
Piotr Latos ◽  
Agnieszka Siewniak ◽  
Natalia Barteczko ◽  
Sebastian Jurczyk ◽  
Sławomir Boncel ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Ionic Liquids ◽  
High Selectivity ◽  
Active Phase ◽  
Catalytic Performance ◽  
Reaction Parameters ◽  
Multiwalled Carbon ◽  
Highly Active ◽  
Recyclable Catalysts ◽  
Fold Excess

An effective method for the synthesis of 2,3,6-trimethyl-1,4-benzoquinone via the oxidation of 2,3,6-trimethylphenol as the key step in the in the preparation of vitamin E was presented. An aqueous solution of H2O2 was used as the oxidant and Lewis acidic trifloaluminate ionic liquids [emim][OTf]-Al(OTf)3, χAl(OTf)3 = 0.25 or 0.15 as catalysts. Trifloaluminate ionic liquids were synthesised by the simple reaction between 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (triflate) [emim][OTf] and aluminium triflate used in sub-stoichiometric quantities. The influence of the reaction parameters on the reaction course, such as the amount and concentration of the oxidant, the amount of catalyst, the amount and the type of organic solvent, temperature, and the reaction time was investigated. Finally, 2,3,6-trimethyl-1,4-benzoquinone was obtained in high selectivity (99%) and high 2,3,6-trimethylphenol conversion (84%) at 70 °C after 2 h of oxidation using a 4-fold excess of 60% aqueous H2O2 and acetic acid as the solvent. The catalytic performance of trifloaluminate ionic liquids supported on multiwalled carbon nanotubes (loading of active phase: 9.1 wt.%) was also demonstrated. The heterogeneous ionic liquids not only retained their activity compared to the homogenous counterparts, but also proved to be a highly recyclable catalysts.

Tuning the catalytic performance of Co/Mg-La system for ammonia synthesis via the active phase precursor introduction method

2020 ◽  
Vol 598 ◽  
pp. 117553 ◽  
Author(s):  
Hubert Ronduda ◽  
Magdalena Zybert ◽  
Wojciech Patkowski ◽  
Aleksandra Tarka ◽  
Przemysław Jodłowski ◽  
...  
Keyword(s):  
Ammonia Synthesis ◽  
Active Phase ◽  
Catalytic Performance ◽  
Phase Precursor

scholarly journals Catalytic Performance of Bulk and Al2O3-Supported Molybdenum Oxide for the Production of Biodiesel from Oil with High Free Fatty Acids Content

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 158 ◽  
Author(s):  
Alberto Navajas ◽  
Inés Reyero ◽  
Elena Jiménez-Barrera ◽  
Francisca Romero-Sarria ◽  
Jordi Llorca ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Molybdenum Oxide ◽  
Solid Acid ◽  
Reaction Medium ◽  
Active Phase ◽  
Catalytic Performance ◽  
Acid Catalysts ◽  
Basic Catalysts ◽  
Esterification Reactions

Non-edible vegetable oils are characterized by high contents of free fatty acids (FFAs) that prevent from using the conventional basic catalysts for the production of biodiesel. In this work, solid acid catalysts are used for the simultaneous esterification and transesterification with methanol of the FFAs and triglycerides contained in sunflower oil acidified with oleic acid. Molybdenum oxide (MoO3), which has been seldom considered as a catalyst for the production of biodiesel, was used in bulk and alumina-supported forms. Results showed that bulk MoO3 is very active for both transesterification and esterification reactions, but it suffered from severe molybdenum leaching in the reaction medium. When supported on Al2O3, the MoO3 performance improved in terms of active phase utilization and stability though molybdenum leaching remained significant. The improvement of catalytic performance was ascribed to the establishment of MoO3-Al2O3 interactions that favored the anchorage of molybdenum to the support and the formation of new strong acidic centers, although this effect was offset by a decrease of specific surface area. It is concluded that the development of stable catalysts based on MoO3 offers an attractive route for the valorization of oils with high FFAs content.

scholarly journals Structural and Oxidative Properties of Manganese Incorporated Mesostructure Silica for Methane Oxidation

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Rihem Dardouri ◽  
Anis Gannouni ◽  
Mongia Saïd Zina
Keyword(s):  
Ion Exchange ◽  
Methane Oxidation ◽  
Crystalline Phase ◽  
Synthesis Method ◽  
Porous Silica ◽  
Chemical Properties ◽  
Active Phase ◽  
Catalytic Performance ◽  
Adsorption Desorption ◽  
Mcm 41

Manganese catalysts containing templated mesostructured porous silica were prepared using different methods of preparation, namely, the direct hydrothermal (DHT), solid-state ion exchange (SSI), template ion exchange (TIE), and impregnation (Imp) methods. The physical-chemical properties of materials were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, FT-IR, TEM, EDX, UV-Vis, EPR, and H2 TPR techniques. The results of this study indicate that the obtained catalysts retained their hexagonal mesopore structure after introducing Mn into MCM-41. On the contrary, the crystalline phase of manganese oxide was stabilized on the external surface and inside the mesoporosity of the MCM-41 and seems to be dependent on the synthesis method used. Catalytic performances of synthesized materials were then investigated in methane oxidation at atmospheric pressure. The results showed that the metal loading and catalysts synthesis procedure influence the catalytic performance of the obtained materials. Moreover, the activity of the catalyst depends on the crystalline phase and particularly on the environment of the active phase.

Effects of Carrier on Supported Rare Earth Double Perovskite Oxide Catalysts for Catalytic Combustion of Methane

2012 ◽  
Vol 512-515 ◽  
pp. 1601-1606 ◽  
Author(s):  
Ran Ran Ding ◽  
Jia Nan Hu ◽  
Rui Sheng Hu ◽  
Ying Liu ◽  
Ling Jie Wang
Keyword(s):  
Rare Earth ◽  
Catalytic Combustion ◽  
Supported Catalyst ◽  
Double Perovskite ◽  
Active Phase ◽  
Catalytic Performance ◽  
Oxide Catalysts ◽  
Perovskite Oxide ◽  
Impregnation Method ◽  
Oxide Support

Supported rare earth double perovskite (La2MnNiO6) oxide catalysts were prepared by incipient wet impregnation method for methane catalytic combustion, and effects of the support (Al2O3, ZrO2 and MgO) were investigated. The loaded catalysts were characterized by means of XRD, TPR, SEM techniques and their catalytic activities were tested by complete methane oxidation. Depending on the different oxide carrier (e.g. Al2O3, MgO and ZrO2), catalysts have different catalytic properties, because the interaction of metal oxide-support will affect both redox property and dispersity of the active phase. The results on catalysts have shown that the dispersion on Al2O3 and MgO supports had an effect to enhance the catalytic performances of the catalysts that had been treated at 1100 oC. The activity of ZrO2 supported catalyst significantly decreases when calcination temperature at is 1100 oC. The dispersity of the active phase and the nature of the oxide carrier played an important role in the catalytic performance.

scholarly journals Modified Zeolite Catalyst for a NOx Selective Catalytic Reduction Process in Nitric Acid Plants

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 450
Author(s):  
Magdalena Saramok ◽  
Agnieszka Szymaszek ◽  
Marek Inger ◽  
Katarzyna Antoniak-Jurak ◽  
Bogdan Samojeden ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Reduction Process ◽  
Active Phase ◽  
Catalytic Performance ◽  
Temperature Range ◽  
Nh3 Scr ◽  
Modified Clinoptilolite

Natural zeolite of the heulandite-type framework was modified with iron and tested as a catalyst for the selective catalytic reduction of nitrogen oxides with ammonia (NH3-SCR) in the temperature range of 150–450 °C. The catalyst was prepared at a laboratory scale in a powder form and then the series of experiments of its shaping into tablets was conducted. Physicochemical studies of the catalyst (N2 sorption at −196 °C, FT-IR, XRD, UV-vis) were performed to determine the textural and structural properties and identify the surface functional groups, the crystalline structure of the catalysts and the form and aggregation of the active phase. The activity tests over the shaped catalyst were performed industry-reflecting conditions, using tail gases from the pilot nitric acid plant. The influence of a temperature, catalyst load, and the amount of reducing agent (ammonia) on the NOx reduction process were investigated. The results of catalytic tests that were performed on model gas mixture showed that non-modified clinoptilolite exhibited around 58% conversion of NO at 450 °C. The temperature window of the shaped catalyst shifted to a higher temperature range in comparison to the powder sample. The catalytic performance of the shaped Fe-clinoptilolite in the industry-reflecting conditions was satisfactory, especially at 450 °C. Additionally, it was observed that the ratio of N2O concentration downstream and upstream of the catalytic bed was below 1, which indicated that the catalyst exhibited activity in both DeNOx and DeN2O process.

scholarly journals Effect of Metal Loading in Unpromoted and Promoted CoMo/Al2O3–TiO2 Catalysts for the Hydrodeoxygenation of Phenol

Catalysts ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 550 ◽  
Author(s):  
J. Andrés Tavizón-Pozos ◽  
Carlos E. Santolalla-Vargas ◽  
Omar U. Valdés-Martínez ◽  
José Antonio de los Reyes Heredia
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Mixed Oxides ◽  
Batch Reactor ◽  
Sol Gel ◽  
Active Phase ◽  
Catalytic Performance ◽  
Octahedral Coordination ◽  
Optimum Amount ◽  
Co Concentration

This paper reports the effects of changes in the supported active phase concentration over titania containing mixed oxides catalysts for hydrodeoxygenation (HDO). Mo and CoMo supported on sol–gel Al2O3–TiO2 (Al/Ti = 2) were synthetized and tested for the HDO of phenol in a batch reactor at 5.5 MPa, 593 K, and 100 ppm S. Characterization results showed that the increase in Mo loading led to an increase in the amount of oxide Mo species with octahedral coordination (MoOh), which produced more active sites and augmented the catalytic activity. The study of the change of Co concentration allowed prototypes of the oxide species and their relationship with the CoMo/AT2 activity to be described. Catalysts were tested at four different Co/(Co + Mo) ratios. The results presented a correlation between the available fraction of CoOh and the catalytic performance. At low CoOh fractions (Co/(Co + Mo) = 0.1), Co could not promote all MoS2 slabs and metallic sites from this latter phase performed the reaction. Also, at high Co/(Co + Mo) ratios (0.3 and 0.4), there was a loss of Co species. The Co/(Co + Mo) = 0.2 ratio presented an optimum amount of available CoOh and catalytic activity since the XPS results indicated a higher concentration of the CoMoS phase than at a higher ratio.

scholarly journals Oscillatory Behavior of Pd-Au Catalysts in Toluene Total Oxidation

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 574 ◽  
Author(s):  
Tarek Barakat ◽  
Joanna Rooke ◽  
Dayan Chlala ◽  
Renaud Cousin ◽  
Jean-François Lamonier ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Active Phase ◽  
Catalytic Performance ◽  
Reaction Scheme ◽  
Oscillatory Behavior ◽  
Oh Radicals ◽  
Oxidation Reactions ◽  
Total Oxidation ◽  
Diffuse Reflectance Infrared

In this work, the activity of bimetallic Pd-Au doped hierarchically structured titania catalysts has been investigated in the total oxidation of toluene. In earlier works, doping titania with group Vb metal oxides ensured an increased catalytic performance in the elimination of VOC molecules. A synergy between gold and palladium loaded at the surface of titania supports provided better performances in VOC oxidation reactions. Therefore, the main focus in this work was to investigate the durability of the prepared catalysts under long time-on-stream periods. Vanadium-doped catalysts showed a stable activity throughout the whole 110 h test, whereas, surprisingly, niobium-doped catalysts presented a cycle-like activity while nevertheless maintaining a high performance in toluene elimination. Operando Diffuse Reflectance Infrared Fourrier Transform spectroscopy (DRIFT) experiments revealed that variations in the presence of OH radicals and the presence of carbonaceous compounds adsorbed at the surface of spent catalysts varies with the occurrence of oscillations. X-ray Photoelectron Spectroscopy (XPS) results show that interactions between the material and the active phase provided extra amounts of mobile oxygen species and participated in easing the reduction of palladium. An enhanced redox reaction scheme is thus obtained and allows the occurrence of the cyclic-like performance of the catalyst.

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