scholarly journals Identification of Active Sites in the Catalytic Oxidation of 2‐Propanol over Co1+xFe2‐xO4 Spinel Oxides at Solid/Liquid and Solid/Gas Interfaces

ChemCatChem ◽  
2021 ◽  
Author(s):  
Tobias Falk ◽  
Eko Budiyanto ◽  
Maik Dreyer ◽  
Christin Pflieger ◽  
Daniel Waffel ◽  
...  
Keyword(s):  
Catalytic Oxidation ◽  
Active Sites ◽  
Spinel Oxides ◽  
Solid Liquid

scholarly journals Integration of surface science, nanoscience, and catalysis

2010 ◽  
Vol 83 (1) ◽  
pp. 243-252 ◽  
Author(s):  
Cun Wen ◽  
Yi Liu ◽  
Franklin Tao
Keyword(s):  
Heterogeneous Catalysis ◽  
Single Crystal ◽  
Surface Science ◽  
Active Sites ◽  
Liquid Interfaces ◽  
Design Studies ◽  
The Past ◽  
Catalytic Active Sites ◽  
Catalytic Mechanisms ◽  
Solid Liquid

This article briefly reviews the development of surface science and its close relevance to nanoscience and heterogeneous catalysis. The focus of this article is to highlight the importance of nanoscale surface science for understanding heterogeneous catalysis performing at solid–gas and solid–liquid interfaces. Surface science has built a foundation for the understanding of catalysis based on the studies of well-defined single-crystal catalysts in the past several decades. Studies of catalysis on well-defined nanoparticles (NPs) significantly promoted the understanding of catalytic mechanisms to an unprecedented level in the last decade. To understand reactions performed on catalytic active sites at nano or atomic scales and thus reach the goal of catalysis by design, studies of the surface of nanocatalysts are crucial. The challenges in such studies are discussed.

Promotion of A-Site Ag-Doped Perovskites for the Catalytic Oxidation of Soot: Synergistic Catalytic Effect of Dual Active Sites

ACS Catalysis ◽  
2021 ◽  
pp. 14224-14236
Author(s):  
Lijun He ◽  
Yan Zhang ◽  
Yuchao Zang ◽  
Caixia Liu ◽  
Weichao Wang ◽  
...  
Keyword(s):  
Catalytic Oxidation ◽  
Active Sites ◽  
Catalytic Effect ◽  
A Site

EFFECTS OF FINITE REACTION RATES ON THE KINETIC PHASE TRANSITIONS IN THE CATALYTIC OXIDATION OF CARBON MONOXIDE

2002 ◽  
Vol 09 (05n06) ◽  
pp. 1735-1739
Author(s):  
L. D. LÓPEZ-CARREÑO
Keyword(s):  
Carbon Monoxide ◽  
Phase Transitions ◽  
Steady State ◽  
Catalytic Oxidation ◽  
Active Sites ◽  
Nearest Neighbor ◽  
Reaction Rates ◽  
Neighbor Site ◽  
State Configuration ◽  
Oxidation Of Carbon Monoxide

Oxidation of carbon monoxide is one of the most extensively studied heterogeneous catalysis reactions, being important among other applications in automobile-emission control. Catalytic oxidation of carbon monoxide on platinum (111) surface was simulated by the Monte Carlo technique following an extended version of the model proposed by Ziff, Gulari and Barshad (ZGB). In the simulation, a simple square two-dimensional lattice of active sites replaces the surface of the catalyst. Finite reaction rates for (i) diffusion of the reactive species on the surface, (ii) reaction of a CO molecule with an oxygen atom in a nearest neighbor site, and (iii) desorption of unreacted CO molecules, have been taken into account. The produced CO 2 desorbs instantly. The average coverage of O, CO and the CO 2 production rate for a steady state configuration, as a function of the normalized CO partial pressure (P CO ), shows two kinetic phase transitions. In the ZGB model these transitions occur at P CO ≈ 0.39 and P CO ≈ 0.53. For 0.39 < P CO < 0.53 a reactive ( CO 2 production) steady state is found. Outside of the interval, the only steady state is a poisoned catalyst of pure CO or pure O. Our results show that finite reaction rates shift the values in which these phase transitions occur.

scholarly journals Novel lignocellulosic wastes for comparative adsorption of Cr(VI): equilibrium kinetics and thermodynamic studies

2017 ◽  
Vol 19 (2) ◽  
pp. 6-15 ◽  
Author(s):  
Hajira Haroon ◽  
Syed Mubashar Hussain Gardazi ◽  
Tayyab Ashfaq Butt ◽  
Arshid Pervez ◽  
Qaisar Mahmood ◽  
...  
Keyword(s):  
Active Sites ◽  
Low Cost ◽  
Liquid Interface ◽  
Order Kinetic ◽  
Batch Mode ◽  
Adsorption Sites ◽  
Equilibrium Data ◽  
Controlled Adsorption ◽  
Solid Liquid Interface ◽  
Solid Liquid

Abstract Cr(VI) adsorption was studied for abundantly available low-cost lignocellulosic adsorbents in Pakistan namely, tobacco stalks (TS), white cedar stem (WCS) and eucalyptus bark (EB). Several process variables like contact time, adsorbent dose, pH, metal concentration, particle size and temperature were optimized in batch mode. EB showed high Cr(VI) adsorption of 63.66% followed by WCS 62% and TS 57% at pH 2, which is higher than most of the reported literature. Langmuir isotherm (R2 = 0.999) was well fitted into the equilibrium Cr(VI) data of EB, suggesting homogeneous active sites and monolayer coverage of Cr(VI) onto the EB surface. Freundlich (R2 = 0.9982) isotherm was better fitted to the equilibrium data of TS and WCS, revealing the adsorption sites with heterogeneous energy distribution and multilayer Cr(VI) adsorption. Moreover, the Cr(VI) adsorption of studied adsorbents followed the pseudo-second order kinetic model. Thermodynamic properties were investigated in two temperature ranges, i.e., T1 (303–313 K) and T2 (313–323 K). TS and EB showed the exothermic at T1 and endothermic reactions at T2 with entropy controlled adsorption at the solid-liquid interface, and WCS exhibited an opposite thermal trend with decreasing disorderness at solid-liquid interface as temperature rises. Gibbs free energy (ΔG>0) confirmed the non-spontaneous adsorption process for all studied adsorbents.

scholarly journals The influence of porosity on nanoparticle formation in hierarchical aluminophosphates

2019 ◽  
Vol 10 ◽  
pp. 1952-1957 ◽  
Author(s):  
Matthew E Potter ◽  
Lauren N Riley ◽  
Alice E Oakley ◽  
Panashe M Mhembere ◽  
June Callison ◽  
...  
Keyword(s):  
Catalytic Oxidation ◽  
Active Sites ◽  
Dual Porosity ◽  
Hierarchical Systems ◽  
Nanoparticle Deposition ◽  
Gold Particles ◽  
Nanoparticle Formation ◽  
Significant Potential ◽  
Oxidation Reduction ◽  
Deposition Techniques

In this work we explore the deposition of gold onto a silicoaluminophosphate, using a variety of known nanoparticle deposition techniques. By comparing the gold particles deposited on a traditional microporous aluminophosphate, with an analogous hierarchical species, containing both micropores and mesopores, we explore the influence of this dual porosity on nanoparticle deposition. We show that the presence of mesopores has limited influence on the nanoparticle properties, but allows the system to maintain porosity after nanoparticle deposition. This will aid diffusion of reagents through the system, allowing continued access to the active sites in hierarchical systems, which offers significant potential in catalytic oxidation/reduction reactions.

Preparation, Properties and Cytotoxicity Assessment of Nanosized Pt-Rh Composite Catalyst for the Decomposition of Gaseous Ammonia

2010 ◽  
Vol 160-162 ◽  
pp. 1285-1290
Author(s):  
Chang Mao Hung
Keyword(s):  
Catalytic Oxidation ◽  
Active Sites ◽  
Human Lung ◽  
Fixed Bed ◽  
Composite Catalyst ◽  
Gaseous Ammonia ◽  
Human Lung Cells ◽  
Selective Catalytic Oxidation ◽  
Catalytically Active

The behavior of the ammonia (NH3) oxidation was by selective catalytic oxidation (SCO) over a nanosized Pt-Rh composite catalyst in a tubular fixed-bed flow quartz reactor (TFBR) at temperatures between 423 and 673 K. The catalysts surface properties were characterized using UV-Vis and TEM. The experimental results show high activities for NH3 removal was achieved during catalytic oxidation over the Pt-Rh catalyst at 673 K with an oxygen content of 4%. N2 was the main product in the NH3-SCO process over the nanosized Pt-Rh composite catalyst. These results also verify that the Pt-Rh metals on catalyst surfaces, resulting in the formation of the remarkable catalytically active sites at the metal-support interface in the reduction of NH3 in this process. In addition, the nanosized Pt-Rh composite-induced cytotoxicity testing was mainly applied to the human lung MRC-5 cell line and the percentage of cell survival was determined by MTS analysis in vitro. For nanosized Pt-Rh composite, only minor cytotoxicity was observed when human lung cells were exposed.

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