scholarly journals Reaction Mechanism for Selective Synthesis of Gasoline-Range Isoalkanes from Syngas over RuPtHY Zeolites. II. Role of Metals and Acid Sites

1987 ◽  
Vol 60 (7) ◽  
pp. 2335-2341 ◽  
Author(s):  
Yong-Gong Shul ◽  
Yukari Arai ◽  
Takashi Tatsumi ◽  
Hiro-o Tominaga
Keyword(s):  
Reaction Mechanism ◽  
Acid Sites ◽  
Selective Synthesis

scholarly journals On the Role of Protonic Acid Sites in Cu Loaded FAU31 Zeolite as a Catalyst for the Catalytic Transformation of Furfural to Furan

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 2015
Author(s):  
Łukasz Kuterasiński ◽  
Małgorzata Smoliło-Utrata ◽  
Joanna Kaim ◽  
Wojciech Rojek ◽  
Jerzy Podobiński ◽  
...  
Keyword(s):  
Active Sites ◽  
Acid Sites ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brønsted Acid Sites ◽  
Protonic Acid ◽  
Brönsted Acid ◽  
Brönsted Acid Sites ◽  
Bronsted Acid Sites

The aim of the present paper is to study the speciation and the role of different active site types (copper species and Brønsted acid sites) in the direct synthesis of furan from furfural catalyzed by copper-exchanged FAU31 zeolite. Four series of samples were prepared by using different conditions of post-synthesis treatment, which exhibit none, one or two types of active sites. The catalysts were characterized by XRD, low-temperature sorption of nitrogen, SEM, H2-TPR, NMR and by means of IR spectroscopy with ammonia and CO sorption as probe molecules to assess the types of active sites. All catalyst underwent catalytic tests. The performed experiments allowed to propose the relation between the kind of active centers (Cu or Brønsted acid sites) and the type of detected products (2-metylfuran and furan) obtained in the studied reaction. It was found that the production of 2-methylfuran (in trace amounts) is determined by the presence of the redox-type centers, while the protonic acid sites are mainly responsible for the furan production and catalytic activity in the whole temperature range. All studied catalysts revealed very high susceptibility to coking due to polymerization of furfural.

Reaction Mechanism for CCl2F2 Catalytic Decomposition over MoO3/ZrO2

2013 ◽  
Vol 295-298 ◽  
pp. 326-330 ◽  
Author(s):  
Tian Cheng Liu ◽  
Yu Jiao Guo ◽  
Ping Ning ◽  
Ming Long Yuan
Keyword(s):  
Reaction Mechanism ◽  
Main Product ◽  
Solid Acid ◽  
Fixed Bed ◽  
Catalytic Decomposition ◽  
Strong Acid ◽  
Acid Sites ◽  
Fixed Bed Reactor ◽  
Surface Intermediate ◽  
Strong Acid Sites

Catalytic hydrolysis decomposition of dichlorodifluoromethane (CCl2F2) in the presence of water vapor and oxygen was studied over a series of solid acids using a fixed-bed reactor. Solid acid MoO3/ZrO2 displayed the highest activity, over which the conversion of CCl2F2 reached 100 % at 250 °C. CO2 was the main-product and the selectivity to CClF3 remained lower than 28.0 %. CO was not detected as by-product. The decomposition activity depended on the calcination temperature and the ZrO2 content. The activity of solid acid MoO3/ZrO2 correlates well with its specific surface area and the amount of medium-strong acid sites on the surface. To explain the reaction mechanism for CCl2F2 catalytic decomposition over MoO3/ZrO2, a surface intermediate, Osurface-CF2-Osurface is proposed.

scholarly journals Oxidation of Ethanol in Cu-Faujasites Studied by IR Spectroscopy

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2669
Author(s):  
Łukasz Kuterasiński ◽  
Jerzy Podobiński ◽  
Jerzy Datka
Keyword(s):  
Ethanol Oxidation ◽  
Produced Water ◽  
Acid Sites ◽  
No Adsorption ◽  
Ir Studies ◽  
Oxygen Donor ◽  
Before And After ◽  
Acetate Formation ◽  
Back Donation

In this study, IR studies of the coadsorption of ethanol and CO on Cu+ cations evidenced the transfer of electrons from ethanol to Cu+, which caused the lowering of the frequency of the band attributed to CO bonded to the same Cu+ cation due to the more effective π back donation of d electrons of Cu to antibonding π* orbitals of CO. The reaction of ethanol with acid sites in zeolite HFAU above 370 K produced water and ethane, polymerizing to polyethylene. Ethanol adsorbed on zeolite Cu(2)HFAU containing acid sites and Cu+exch also produced ethene, but in this case, the ethene was bonded to Cu+ and did not polymerize. C=C stretching, which is IR non-active in the free ethene molecule, became IR active, and a weak IR band at 1538 cm−1 was present. The reaction of ethanol above 370 K in Cu(5)NaFAU zeolite (containing small amounts of Cu+exch and bigger amounts of Cu+ox, Cu2+exch and CuO) produced acetaldehyde, which was further oxidized to the acetate species (CH3COO-). As oxygen was not supplied, the donors of oxygen were the Cu species present in our zeolite. The CO and NO adsorption experiments performed in Cu-zeolite before and after ethanol reaction evidenced that both Cu+ox and Cu2+ (Cu2+exch and CuO) were consumed by the ethanol oxidation reaction. The studies of the considered reaction of bulk CuO and Cu2O as well as zeolites, in which the contribution of Cu+ox species was reduced by various treatments, suggest that ethanol was oxidized to acetaldehyde by Cu2+ox (the role of Cu+ox could not be elucidated), but Cu+ox was the oxygen donor in the acetate formation.

Oxidations ofNω-Hydroxyarginine Analogues and VariousN-Hydroxyguanidines by NO Synthase II: Key Role of Tetrahydrobiopterin in the Reaction Mechanism and Substrate Selectivity

2001 ◽  
Vol 14 (2) ◽  
pp. 202-210 ◽  
Author(s):  
Catherine Moali ◽  
Jean-Luc Boucher ◽  
Axelle Renodon-Corniere ◽  
Dennis J. Stuehr ◽  
Daniel Mansuy
Keyword(s):  
Reaction Mechanism ◽  
No Synthase ◽  
Substrate Selectivity

Role of Acid Sites on γ-Al2O3 Based Catalyst for CF4 Hydrolysis

2011 ◽  
Vol 37 (2) ◽  
pp. 175-180
Author(s):  
Takashi Sasaki ◽  
Shuichi Kanno
Keyword(s):  
Acid Sites

Reaction Mechanism and Role of the Support in the Partial Oxidation of Methane on Rh/Al2O3

1996 ◽  
Vol 159 (2) ◽  
pp. 418-426 ◽  
Author(s):  
Dezheng Wang ◽  
Olivier Dewaele ◽  
Ann M.De Groote ◽  
Gilbert F. Froment
Keyword(s):  
Reaction Mechanism ◽  
Partial Oxidation ◽  
Partial Oxidation Of Methane ◽  
Oxidation Of Methane

γ-Alumina and Amorphous Silica–Alumina: Structural Features, Acid Sites and the Role of Adsorbed Water

2017 ◽  
Vol 60 (19-20) ◽  
pp. 1554-1564 ◽  
Author(s):  
Vicente Sanchez Escribano ◽  
Gabriella Garbarino ◽  
Elisabetta Finocchio ◽  
Guido Busca
Keyword(s):  
Amorphous Silica ◽  
Adsorbed Water ◽  
Structural Features ◽  
Acid Sites ◽  
Silica Alumina
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