scholarly journals Hollow PdAg-CeO2 heterodimer nanocrystals as highly structured heterogeneous catalysts

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Javier Patarroyo ◽  
Jorge A. Delgado ◽  
Florind Merkoçi ◽  
Aziz Genç ◽  
Guillaume Sauthier ◽  
...  
Keyword(s):  
Beneficial Effect ◽  
Selective Hydrogenation ◽  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Catalytic Properties ◽  
Reaction Times ◽  
Catalytic Performance ◽  
Internal Alkynes ◽  
First Time ◽  
Full Conversion

AbstractIn the present work, hollow PdAg-CeO2 heterodimer nanocrystals (NCs) were prepared and tested as catalysts for the selective hydrogenation of alkynes. These nanostructures combine for the first time the beneficial effect of alloying Pd with Ag in a single NC hollow domain with the formation of active sites at the interface with the CeO2 counterpart in an additive manner. The PdAg-CeO2 NCs display excellent alkene selectivity for aliphatic alkynes. For the specific case of hydrogenation of internal alkynes such as 4-octyne, very low over-hydrogenation and isomerization products were observed over a full conversion regime, even after prolonged reaction times. These catalytic properties were remarkably superior in comparison to standard catalysts. The promotion of Ag on the moderation of the reactivity of the Pd phase, in combination with the creation of interfacial sites with the CeO2 moiety in the same nanostructure, is pointed as the responsible of such a remarkable catalytic performance.

scholarly journals Dual-atom Pt heterogeneous catalyst with excellent catalytic performances for the selective hydrogenation and epoxidation

2020 ◽  
Author(s):  
Shubo Tian ◽  
Zizhan He ◽  
Wanbing Gong ◽  
Qi Xu ◽  
Wenxing Chen ◽  
...  
Keyword(s):  
Selective Hydrogenation ◽  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Pt Nanoparticles ◽  
Catalytic Performance ◽  
Utilization Efficiency ◽  
Heterogeneous Catalytic ◽  
Formidable Challenge ◽  
Wet Chemical ◽  
Dual Atom

Abstract Atomically monodispersed heterogeneous catalysts with uniform active sites and high atom utilization efficiency are ideal heterogeneous catalytic materials. Designing such type of catalysts, however, remains a formidable challenge. Herein, using a wet-chemical method, we successfully achieved a mesoporous graphitic carbon nitride (mpg-C3N4) supported dual-atom Pt2 catalyst, which exhibited excellent catalytic performance for the highly selective hydrogenation of nitrobenzene to aniline. The conversion of ˃99% is significantly superior to the corresponding values of mpg-C3N4-supported single Pt atoms and ultra-small Pt nanoparticles. First-principles calculations revealed that the excellent performance of the dual-atomic Pt2 species originates from an effective activation of the nitro groups in the reactant. The produced Pt2/mpg-C3N4 samples are versatile and can be applied in catalyzing other important reactions, such as the selective hydrogenation of benzaldehyde and the epoxidation of styrene.

scholarly journals Dual-atom Pt heterogeneous catalyst with excellent catalytic performances for the selective hydrogenation and epoxidation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shubo Tian ◽  
Bingxue Wang ◽  
Wanbing Gong ◽  
Zizhan He ◽  
Qi Xu ◽  
...  
Keyword(s):  
Selective Hydrogenation ◽  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Pt Nanoparticles ◽  
Catalytic Performance ◽  
Utilization Efficiency ◽  
Heterogeneous Catalytic ◽  
Formidable Challenge ◽  
Wet Chemical ◽  
Dual Atom

AbstractAtomically monodispersed heterogeneous catalysts with uniform active sites and high atom utilization efficiency are ideal heterogeneous catalytic materials. Designing such type of catalysts, however, remains a formidable challenge. Herein, using a wet-chemical method, we successfully achieved a mesoporous graphitic carbon nitride (mpg-C3N4) supported dual-atom Pt2 catalyst, which exhibited excellent catalytic performance for the highly selective hydrogenation of nitrobenzene to aniline. The conversion of ˃99% is significantly superior to the corresponding values of mpg-C3N4-supported single Pt atoms and ultra-small Pt nanoparticles (~2 nm). First-principles calculations revealed that the excellent and unique catalytic performance of the Pt2 species originates from the facile H2 dissociation induced by the diatomic characteristics of Pt and the easy desorption of the aniline product. The produced Pt2/mpg-C3N4 samples are versatile and can be applied in catalyzing other important reactions, such as the selective hydrogenation of benzaldehyde and the epoxidation of styrene.

scholarly journals Synthesis of new bimetallic phosphate (Al/Ag3PO4) and study for its Catalytic performance in the synthesis of 1,2-dihydro-l-phenyl-3H-naphth [1,2-e]-[1,3] oxazin-3-one derivatives

2021 ◽  
Vol 11 (3) ◽  
pp. 215
Author(s):  
Achraf El Hallaoui ◽  
Tourya Ghailane ◽  
Soukaina Chehab ◽  
Youssef Merroun ◽  
Rachida Ghailane ◽  
...  
Keyword(s):  
Reaction Times ◽  
Catalytic Performance ◽  
X Ray Diffraction ◽  
One Pot ◽  
X Ray ◽  
Silver Sulfate ◽  
Triple Super Phosphate ◽  
Aryl Aldehyde ◽  
Ft Ir ◽  
First Time

<p>This work aims to prepare a new bimetallic phosphate catalyst using a new simple and effective method. This new catalyst was ready for the first time by a modification of Triple Super Phosphate (TSP) fertilizer with silver sulfate (AgSO<sub>4</sub>), followed by the impregnation of the aluminum atoms using aluminum nitrate (Al(NO<sub>3</sub>)<sub>3</sub>). The use of Al/Ag<sub>3</sub>PO<sub>4</sub>, for the first time as a heterogeneous catalyst in organic chemistry, offers a new, efficient, and green pathway for synthesizing 1,2-dihydro-l-phenyl-3H-naphth[1,2-e]-[1,3]oxazin-3-one derivatives by one-pot three-component cyclocondensation of b-naphthol, aryl aldehyde, and urea. The structure and the morphology of the prepared catalyst were characterized by spectroscopic methods such as X-Ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR), and dispersive X-ray spectrometry coupled with a scanning electron microscope (EDX-SEM). In addition, the optimization of the reaction parameters was carried out considering the effect of catalyst amount, the temperature, and the solvent. The procedure described herein allowed a comfortable preparation of oxazine derivatives with excellent yields, short reaction times, and in the absence of organic solvent.</p>

scholarly journals Catalytic Performance of SBA-15-Supported Poly (Styrenesulfonic Acid) in the Esterification of Acetic Acid with n-Heptanol

2020 ◽  
Vol 10 (17) ◽  
pp. 5835
Author(s):  
Abdulaziz Ali Alghamdi ◽  
Yahya Musawi Mrair ◽  
Fahad A. Alharthi ◽  
Abdel-Basit Al-Odayni
Keyword(s):  
Acetic Acid ◽  
Sulfonic Acid ◽  
Active Sites ◽  
Structural Characteristics ◽  
High Surface ◽  
High Surface Area ◽  
Reaction Times ◽  
Hydrophobic Surface ◽  
Catalytic Performance ◽  
Catalyst Load

A polystyrene sulfonic acid-functionalized mesoporous silica (SBA-15-PSSA) catalyst was synthesized via an established multistep route, employing 2-bromo-2-methylpropionyl bromide as initiator of atom transfer radical polymerization. Fourier-transform infrared spectroscopy, thermogravimetric/differential thermal, Brunauer–Emmett–Teller, and transmission electron microscopy analyses revealed outstanding structural characteristics of the catalyst, including highly ordered mesopores, high surface area (726 m2/g), and adequate estimated concentrations of active sites (0.70 mmol H+/g). SBA-15-PSSA’s catalytic performance was evaluated in the esterification of acetic acid and n-heptanol as a model system at various temperatures (50–110 °C), catalyst loads (0.1–0.3 g), and reaction times (0–160 min). The conversion percentage of acetic acid was found to increase with the temperature, catalyst load, and reaction time. Furthermore, results indicated a fast conversion in the first 20 min of the reaction, with remarkable conversion values at 110 °C, reaching 86%, 94%, and 97% when the catalyst load was 0.1, 0.2, and 0.3 g, respectively; notably, at this temperature, 100% conversation was achieved after 60 min. At 110 °C, the reaction conducted in the presence of 0.3 g of catalyst displayed more than 6.4 times the efficiency of the uncatalyzed reaction. Such activity is explained by the concomitant presence in the polymer of strong sulfonic acid moieties and a relatively high hydrophobic surface, with adequate numbers of active sites for ester production.

An Efficient and Reusable Multifunctional Composite Magnetic Nanocatalyst for Knoevenagel Condensation

Synlett ◽  
2019 ◽  
Vol 30 (06) ◽  
pp. 699-702 ◽  
Author(s):  
Yu Hu ◽  
Nan Yao ◽  
Jin Tan ◽  
Yang Liu
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Knoevenagel Condensation ◽  
Metal Organic Framework ◽  
Catalytic Performance ◽  
Significant Loss ◽  
Magnetic Nanocatalyst ◽  
Metal Organic ◽  
Nife2o4 Nanoparticles ◽  
Organic Framework

A range of multifunctional magnetic metal–organic framework nanomaterials consisting of various mass ratios of the metal–organic framework MIL-53(Fe) and magnetic SiO2@NiFe2O4 nanoparticles were designed, prepared, characterized, and evaluated as heterogeneous catalysts for the Knoevenagel condensation. The as-fabricated nanomaterials, especially the nanocatalyst MIL-53(Fe)@SiO2@NiFe2O4(1.0), showed good catalytic performance in the Knoevenagel condensation at room temperature as a result of synergistic interaction between the Lewis acid iron sites of MIL-53(Fe) and the active sites of the magnetic SiO2@NiFe2O4 nanoparticles. In addition, the heterogeneous catalyst was readily recovered and a recycling test showed that it could be reused for five times without significant loss of its catalytic activity, making it economical and environmentally friendly.

XPS AND FTIR STUDIES OF Mo/ZSM-5 CATALYSTS FOR NONOXIDATIVE CONVERSION OF METHANE TO AROMATICS

2001 ◽  
Vol 08 (06) ◽  
pp. 627-632 ◽  
Author(s):  
H. Y. CHEN ◽  
S. TANG ◽  
Z. Y. ZHONG ◽  
J. LIN ◽  
K. L. TAN
Keyword(s):  
Methane Conversion ◽  
Active Sites ◽  
Reaction Times ◽  
Initial Reaction ◽  
Oxygen Treatment ◽  
Conversion Of Methane ◽  
Xps Study ◽  
Nonoxidative Conversion ◽  
First Time

In this investigation, several Mo/ZSM-5 catalysts with various Mo loadings and various reaction times were prepared, and methane conversion to aromatics without the presence of oxygen was studied by microreactor evaluation, FTIR and XPS. It was found, for the first time, that oxygen treatment before the reaction could shorten the induction period of this reaction. In situ FTIR study indicated the formation of [Formula: see text] species ( 888 cm -1) and O–Al ( 670 cm -1) on the surface of the catalyst as a result of the oxygen treatment. The two IR bands shifted to 854 and 659 cm -1 respectively when 18 O 2 was used. These oxygen species may take part in the initial reaction and shorten the induction time. The XPS study revealed the coexistence of Mo 2 C and MoO 3 species on working catalyst surfaces, and a proper Mo 2 C/MoO 3 ratio (~0.38) was identified for the best aromatization Mo/ZSM-5 catalyst. The active sites for methane conversion to aromatics should include Mo oxide as well as Mo carbide.

Liquid-Phase Selective Hydrogenation of Nitrobenzene over Ultrasonic-Assisted Ni-Mo-P Amorphous Catalyst

2012 ◽  
Vol 550-553 ◽  
pp. 420-423 ◽  
Author(s):  
Qian Wen Dai ◽  
Zi Li Liu ◽  
Cui Xia Xu ◽  
Qi Gang Xie ◽  
Fan Zhang ◽  
...  
Keyword(s):  
Particle Size ◽  
Liquid Phase ◽  
Selective Hydrogenation ◽  
Active Sites ◽  
Reduction Method ◽  
Chemical Reduction ◽  
Catalytic Performance ◽  
Chemical Reduction Method ◽  
Ultrasonic Assisted ◽  
Optimal Reaction

The Ni-Mo-P amorphous catalysts were prepared by chemical reduction method under different sonication conditions. The catalytic performance of the prepared catalysts in selective hydrogenation of nitrobenzene(NB) to aniline(AN) were characterized by XRD, BET, N2-adsorption, H2-TPR and H2-TPD. The results show that the introduction of ultrasonic can improve the dispersion of the active sites in the catalyst, the particle size of the catalyst is also smaller than the regular prepared Ni-Mo-P amorphous catalyst. And the influences of the sonication power and time on the catalysts were discussed and compared. The optimal sonication condition is 70 W within 25 min, its optimal reaction time is 150 min.

scholarly journals Biodiesel Production over Niobium-Containing Catalysts: A Review

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5506
Author(s):  
Daniel Carreira Batalha ◽  
Márcio José da Silva
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Raw Materials ◽  
Catalytic Performance ◽  
High Specific Surface Area ◽  
Biodiesel Production ◽  
Molar Ratio ◽  
Main Reaction ◽  
High Catalytic Activity

Nowadays, the synthesis of biofuels from renewable raw materials is very popular. Among the various challenges involved in improving these processes, environmentally benign catalysts compatible with an inexpensive feedstock have become more important. Herein, we report the recent advances achieved in the development of Niobium-containing heterogeneous catalysts as well as their use in routes to produce biodiesel. The efficiency of different Niobium catalysts in esterification and transesterification reactions of lipids and oleaginous raw materials was evaluated, considering the effect of main reaction parameters such as temperature, time, catalyst load, and oil:alcohol molar ratio on the biodiesel yield. The catalytic performance of Niobium compounds was discussed considering the characterization data obtained by different techniques, including NH3-TPD, BET, and Pyr-FT-IR analysis. The high catalytic activity is attributed to its inherent properties, such as the active sites distribution over a high specific surface area, strength of acidity, nature, amount of acidic sites, and inherent mesoporosity. On top of this, recycling experiments have proven that most Niobium catalysts are stable and can be repeatedly used with consistent catalytic activity.

scholarly journals Single-atom catalyst: a rising star for green synthesis of fine chemicals

2018 ◽  
Vol 5 (5) ◽  
pp. 653-672 ◽  
Author(s):  
Leilei Zhang ◽  
Yujing Ren ◽  
Wengang Liu ◽  
Aiqin Wang ◽  
Tao Zhang
Keyword(s):  
Green Synthesis ◽  
Active Sites ◽  
Rational Design ◽  
Heterogeneous Catalysts ◽  
Catalytic Performance ◽  
Research Area ◽  
Single Atom ◽  
Metal Species ◽  
Future Research ◽  
Fine Chemicals

Abstract The green synthesis of fine chemicals calls for a new generation of efficient and robust catalysts. Single-atom catalysts (SACs), in which all metal species are atomically dispersed on a solid support, and which often consist of well-defined mononuclear active sites, are expected to bridge homogeneous and heterogeneous catalysts for liquid-phase organic transformations. This review summarizes major advances in the SAC-catalysed green synthesis of fine chemicals in the past several years, with a focus on the catalytic activity, selectivity and reusability of SACs in various organic reactions. The relationship between catalytic performance and the active site structure is discussed in terms of the valence state, coordination environment and anchoring chemistry of single atoms to the support, in an effort to guide the rational design of SACs in this special area, which has traditionally been dominated by homogeneous catalysis. Finally, the challenges remaining in this research area are discussed and possible future research directions are proposed.

Sign in / Sign up

Export Citation Format

Share Document