Role of the Solvent in the Adsorption−Desorption Equilibrium of Cinchona Alkaloids between Solution and a Platinum Surface:  Correlations among Solvent Polarity, Cinchona Solubility, and Catalytic Performance

2005 ◽  
Vol 109 (1) ◽  
pp. 406-414 ◽  
Author(s):  
Zhen Ma ◽  
Francisco Zaera
Keyword(s):  
Solvent Polarity ◽  
Catalytic Performance ◽  
Cinchona Alkaloids ◽  
Platinum Surface ◽  
Surface Correlations ◽  
Desorption Equilibrium ◽  
Adsorption Desorption

Role of Surfactant-Adsorbent Acidity and Solvent Polarity in Adsorption-Desorption of Surfactants from Nonaqueous Media

Langmuir ◽  
1994 ◽  
Vol 10 (8) ◽  
pp. 2786-2789 ◽  
Author(s):  
S. Krishnakumar ◽  
P. Somasundaran
Keyword(s):  
Solvent Polarity ◽  
Nonaqueous Media ◽  
Adsorption Desorption

Positive Role of Synthesis Method and Hard Template on the Catalytic Performance of SAPO-34 in Methanol to Olefin Reaction.

2020 ◽  
Vol 23 ◽  
Author(s):  
Sajjad Rimaz ◽  
Reza Katal
Keyword(s):  
Particle Size ◽  
Synthesis Method ◽  
Catalytic Performance ◽  
Hard Template ◽  
Structure Directing Agent ◽  
Positive Role ◽  
Methanol To Olefin ◽  
Dg Method ◽  
Synthesis Procedure

: In the present study, SAPO-34 particles were synthesized using hydrothermal (HT) and dry gel (DG) conversion methods in the presence of diethyl amine (DEA) as an organic structure directing agent (SDA). Carbon nanotubes (CNT) were used as hard template in the synthesis procedure to introduce transport pores into the structures of the synthesized samples. The synthesized samples were characterized with different methods to reveal effects of synthesis method and using hard template on their structure and catalytic performance in methanol to olefin reaction (MTO). DG conversion method results in smaller particle size in comparison with hydrothermal method, resulting in enhancing catalytic performance. On the other side, using CNT in the synthesis procedure with DG method results in more reduction in particle size and formation of hierarchical structure which drastically improves catalytic performance.

scholarly journals Insight into Active Centers and Anti-Coke Behavior of Niobium-Containing SBA-15 for Glycerol Dehydration

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 488
Author(s):  
Katarzyna Stawicka ◽  
Maciej Trejda ◽  
Maria Ziolek
Keyword(s):  
Coke Formation ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Silica Matrix ◽  
High Concentration ◽  
Active Centers ◽  
Acidic Sites ◽  
Glycerol Dehydration ◽  
Adsorption Desorption ◽  
Insight Into

Niobium containing SBA-15 was prepared by two methods: impregnation with different amounts of ammonium niobate(V) oxalate (Nb-15/SBA-15 and Nb-25/SBA-15 containing 15 wt.% and 25 wt.% of Nb, respectively) and mixing of mesoporous silica with Nb2O5 followed by heating at 500 °C (Nb2O5/SBA-15). The use of these two procedures allowed obtaining materials with different textural/surface properties determined by N2 adsorption/desorption isotherms, XRD, UV-Vis, pyridine, and NO adsorption combined with FTIR spectroscopy. Nb2O5/SBA-15 contained exclusively crystalline Nb2O5 on the SBA-15 surface, whereas the materials prepared by impregnation had both metal oxide and niobium incorporated into the silica matrix. The niobium species localized in silica framework generated Brønsted (BAS) and Lewis (LAS) acid sites. The inclusion of niobium into SBA-15 skeleton was crucial for the achievement of high catalytic performance. The strongest BAS were on Nb-25/SBA-15, whereas the highest concentration of BAS and LAS was on Nb-15/SBA-15 surface. Nb2O5/SBA-15 material possessed only weak LAS and BAS. The presence of the strongest BAS (Nb-25/SBA-15) resulted in the highest dehydration activity, whereas a high concentration of BAS was unfavorable. Silylation of niobium catalysts prepared by impregnation reduced the number of acidic sites and significantly increased acrolein yield and selectivity (from ca. 43% selectivity for Nb-25/SBA-15 to ca. 61% for silylated sample). This was accompanied by a considerable decrease in coke formation (from 47% selectivity for Nb-25/SBA-15 to 27% for silylated material).

scholarly journals Robust and efficient hydrogenation of carbonyl compounds catalysed by mixed donor Mn(I) pincer complexes

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wenjun Yang ◽  
Ivan Yu. Chernyshov ◽  
Robin K. A. van Schendel ◽  
Manuela Weber ◽  
Christian Müller ◽  
...  
Keyword(s):  
Noble Metal ◽  
Crucial Role ◽  
Carbonyl Compounds ◽  
Catalytic Performance ◽  
Hydrogen Atmosphere ◽  
Pincer Complexes ◽  
Catalyst Activation ◽  
Hydrogenation Catalysts ◽  
Induction Times

AbstractAny catalyst should be efficient and stable to be implemented in practice. This requirement is particularly valid for manganese hydrogenation catalysts. While representing a more sustainable alternative to conventional noble metal-based systems, manganese hydrogenation catalysts are prone to degrade under catalytic conditions once operation temperatures are high. Herein, we report a highly efficient Mn(I)-CNP pre-catalyst which gives rise to the excellent productivity (TOF° up to 41 000 h−1) and stability (TON up to 200 000) in hydrogenation catalysis. This system enables near-quantitative hydrogenation of ketones, imines, aldehydes and formate esters at the catalyst loadings as low as 5–200 p.p.m. Our analysis points to the crucial role of the catalyst activation step for the catalytic performance and stability of the system. While conventional activation employing alkoxide bases can ultimately provide catalytically competent species under hydrogen atmosphere, activation of Mn(I) pre-catalyst with hydride donor promoters, e.g. KHBEt3, dramatically improves catalytic performance of the system and eliminates induction times associated with slow catalyst activation.

The enhanced role of surface amination on the catalytic performance of polyacrylonitrile supported palladium nanoparticles in hydrogen generation from formic acid

2021 ◽  
Vol 138 (20) ◽  
pp. 50456
Author(s):  
Yulin Li ◽  
Lili Chen ◽  
Yanhong Jia ◽  
Da Li ◽  
Xiufeng Hao ◽  
...  
Keyword(s):  
Formic Acid ◽  
Palladium Nanoparticles ◽  
Hydrogen Generation ◽  
Catalytic Performance ◽  
Supported Palladium

The role of KCl in FeCl3–KCl/Al2O3 catalysts with enhanced catalytic performance for ethane oxychlorination

2017 ◽  
Vol 46 (31) ◽  
pp. 10433-10439 ◽  
Author(s):  
Qihua Zhou ◽  
Ruisheng Hu ◽  
Yun Jia ◽  
Hongye Wang
Keyword(s):  
Catalytic Performance ◽  
Mossbauer Spectrum ◽  
Mössbauer Spectrum ◽  
Characterization Studies

The Mossbauer spectrum and other characterization studies proved that the formation of KFeCl4 enhanced the catalytic performance for ethane oxychlorination.

scholarly journals Investigation on the promotional role of Ga2O3 on the CuO–ZnO/HZSM-5 catalyst for CO2 hydrogenation

RSC Advances ◽  
2021 ◽  
Vol 11 (24) ◽  
pp. 14426-14433
Author(s):  
Jie Du ◽  
Yajing Zhang ◽  
Kangjun Wang ◽  
Fu Ding ◽  
Songyan Jia ◽  
...  
Keyword(s):  
Catalytic Performance ◽  
Co2 Hydrogenation ◽  
Hydrogenation Of Co

The additive Ga2O3 improved the catalytic performance of CuO–ZnO/HZSM-5 catalysts for hydrogenation of CO2 to DME.

scholarly journals Ag/CeO2 Composites for Catalytic Abatement of CO, Soot and VOCs

Catalysts ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 285 ◽  
Author(s):  
M. Grabchenko ◽  
N. Mikheeva ◽  
G. Mamontov ◽  
M. Salaev ◽  
L. Liotta ◽  
...  
Keyword(s):  
Noble Metals ◽  
Chemical Properties ◽  
Soot Oxidation ◽  
Catalytic Performance ◽  
Defective Structure ◽  
Metal Support Interaction ◽  
Key Factor ◽  
Metal Support ◽  
Vocs Abatement

Nowadays catalytic technologies are widely used to purify indoor and outdoor air from harmful compounds. Recently, Ag–CeO2 composites have found various applications in catalysis due to distinctive physical-chemical properties and relatively low costs as compared to those based on other noble metals. Currently, metal–support interaction is considered the key factor that determines high catalytic performance of silver–ceria composites. Despite thorough investigations, several questions remain debating. Among such issues, there are (1) morphology and size effects of both Ag and CeO2 particles, including their defective structure, (2) chemical and charge state of silver, (3) charge transfer between silver and ceria, (4) role of oxygen vacancies, (5) reducibility of support and the catalyst on the basis thereof. In this review, we consider recent advances and trends on the role of silver–ceria interactions in catalytic performance of Ag/CeO2 composites in low-temperature CO oxidation, soot oxidation, and volatile organic compounds (VOCs) abatement. Promising photo- and electrocatalytic applications of Ag/CeO2 composites are also discussed.

scholarly journals Things go better with coke: the beneficial role of carbonaceous deposits in heterogeneous catalysis

2016 ◽  
Vol 6 (2) ◽  
pp. 363-378 ◽  
Author(s):  
C. H. Collett ◽  
J. McGregor
Keyword(s):  
Heterogeneous Catalysis ◽  
Heterogeneous Catalysts ◽  
Catalyst Deactivation ◽  
Catalytic Performance ◽  
Fischer Tropsch ◽  
Carbonaceous Deposits ◽  
Beneficial Role ◽  
Catalytic Processes

Carbonaceous deposits on heterogeneous catalysts are traditionally associated with catalyst deactivation. However, they can play a beneficial role in many catalytic processes, e.g. dehydrogenation, hydrogenation, alkylation, isomerisation, Fischer–Tropsch, MTO etc. This review highlights the role and mechanism by which coke deposits can enhance catalytic performance.

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