scholarly journals Nitrous Oxide Adsorption and Decomposition on Zeolites and Zeolite-like Materials

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 398
Author(s):  
Leonid M. Kustov ◽  
Sergey F. Dunaev ◽  
Alexander L. Kustov
Keyword(s):  
Spectroscopic Data ◽  
N2o Decomposition ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Spectroscopic Methods ◽  
Lewis Acid Sites ◽  
Amorphous Systems ◽  
Modified Zeolites ◽  
Mechanism Of The Reaction

Decomposition of N2O on modified zeolites, crystalline titanosilicalites, and related amorphous systems is studied by the catalytic and spectroscopic methods. Zinc-containing HZSM-5 zeolites and titanosilicalites with moderate Ti/Si ratios are shown to exhibit a better catalytic performance in N2O decomposition as compared with conventionally used Cu/HZSM-5 zeolites and amorphous Cu-containing catalysts. Dehydroxylation of the HZSM-5 zeolite by calcination at 1120 K results in an enhancement of the N2O conversion. The mechanism of the reaction and the role of coordinatively unsaturated cations and Lewis acid sites in N2O decomposition are discussed on the basis of the spectroscopic data.

The role of Lewis acid–base pair sites in ZnO–ZnCr2O4 catalysts for cyclization via dehydrogenative condensation of crude glycerol and 1,2-propanediamine for the synthesis of 2,6-dimethylpyrazine

2017 ◽  
Vol 41 (18) ◽  
pp. 9875-9883 ◽  
Author(s):  
Krishna Vankudoth ◽  
A. Hari Padmasri ◽  
Reema Sarkari ◽  
Vijay Kumar Velisoju ◽  
Naresh Gutta ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Base Pair ◽  
Spectroscopic Data ◽  
Crude Glycerol ◽  
Acid Sites ◽  
Acid Base ◽  
Lewis Acid Sites

DRIFT spectroscopic data revealed the role of surface Lewis acid sites on the synthesis of 2,6-dimethylpyrazine.

Role of Zinc in Zn-Loaded ZSM-5 Zeolites in the Aromatization of n-Hexane

1999 ◽  
Vol 64 (1) ◽  
pp. 168-176 ◽  
Author(s):  
Edita Rojasová ◽  
Agáta Smiešková ◽  
Pavol Hudec ◽  
Zdenek Židek
Keyword(s):  
Solid State ◽  
Ion Exchange ◽  
Lewis Acid ◽  
Acid Site ◽  
Acid Sites ◽  
Partial Migration ◽  
Simultaneous Presence ◽  
Lewis Acid Sites ◽  
Strong Lewis Acid

Aromatization of n-hexane over zinc-modified ZSM-5 zeolites was investigated. It was shown that incorporation of zinc by ion exchange into cationic positions of NH4-ZSM-5 zeolite causes acid-site strength redistribution and generation of new relatively strong Lewis acid sites in zeolite increasing the selectivity of n-hexane aromatization in comparison with the parent NH4-ZSM-5 zeolite. Simultaneous presence of Lewis and Broensted acid sites in ZSM-5 zeolite does not affect the strength of Broensted acid sites in zeolite. For the activity/selectivity of aromatization of n-hexane on Zn-modified ZSM-5 zeolites, the amount of Zn and its localization in the cationic positions are decisive. The reaction of n-hexane can be also initiated by the Zn species alone in the cationic positions. ZnO species alone as an extraframework phase was found inactive in the catalyst for aromatization of n-hexane. The influence of ZnO addition on the performance of pure ammonium forms of ZSM-5 zeolites in n-hexane conversion is a result of partial migration of zinc into cationic positions of zeolite by solid-state ion exchange.

scholarly journals Effect of the calcination temperature of cerium–zirconium mixed oxides on the structure and catalytic performance of WO3/CeZrO2 monolithic catalyst for selective catalytic reduction of NOx with NH3

RSC Advances ◽  
2017 ◽  
Vol 7 (39) ◽  
pp. 24177-24187 ◽  
Author(s):  
Haidi Xu ◽  
Mengmeng Sun ◽  
Shuang Liu ◽  
Yuanshan Li ◽  
Jianli Wang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Lewis Acid ◽  
Mixed Oxides ◽  
Catalytic Reduction ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Lewis Acid Sites ◽  
Reduction Of Nox ◽  
Calcined Temperature

The calcined temperature of the carrier obviously affected SCR activity of catalysts, WO3/Ce0.68Zr0.32O2-500 showed the best low-temperature NH3-SCR activity due to its more Lewis acid sites and stronger redox property.

The role of weak Lewis acid sites for methanol thiolation

2019 ◽  
Vol 9 (2) ◽  
pp. 509-516 ◽  
Author(s):  
Manuel Weber-Stockbauer ◽  
Oliver Y. Gutiérrez ◽  
Ricardo Bermejo-Deval ◽  
Johannes A. Lercher
Keyword(s):  
Lewis Acid ◽  
Active Sites ◽  
Acid Sites ◽  
Lewis Acid Sites ◽  
Strong Base

Weak Lewis acid sites combined with strong base sites of Cs+ supported on WS2 and γ-Al2O3 are the active sites in the thiolation of methanol.

Transition metal ions regulate the catalytic performance of Ti0.8M0.2Ce0.2O2+x for the NH3-SCR of NO: the acidic mechanism

RSC Advances ◽  
2015 ◽  
Vol 5 (10) ◽  
pp. 7597-7603 ◽  
Author(s):  
Yuesong Shen ◽  
Yun Su ◽  
Yifan Ma
Keyword(s):  
Transition Metal Ions ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Acid Strength ◽  
Maximum Activity ◽  
Lewis Acid Sites ◽  
Nh3 Scr ◽  
Scr Of No ◽  
Temperature Window ◽  
Active Temperature

The maximum activity is dependent on the number of Lewis acid sites, and the active temperature window is dependent on the acid strength.

Dehydration of lactic acid to acrylic acid over lanthanum phosphate catalysts: the role of Lewis acid sites

2016 ◽  
Vol 18 (34) ◽  
pp. 23746-23754 ◽  
Author(s):  
Zhen Guo ◽  
De Sheng Theng ◽  
Karen Yuanting Tang ◽  
Lili Zhang ◽  
Lin Huang ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Acrylic Acid ◽  
Lewis Acid ◽  
Acid Sites ◽  
Lewis Acid Sites ◽  
Lanthanum Phosphate ◽  
Lewis Acidic Sites ◽  
Acidic Sites ◽  
Nano Rods

Lewis acidic sites on the surface of lanthanum phosphate nano-rods play a crucial role on the catalytic dehydration of lactic acid to acrylic acid.

scholarly journals MOFs vs. zeolites: carbonyl activation with M(iv) catalytic sites

2017 ◽  
Vol 7 (23) ◽  
pp. 5482-5494 ◽  
Author(s):  
Francisco G. Cirujano
Keyword(s):  
Lewis Acid ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Lewis Acid Sites ◽  
Comparative Review ◽  
Catalytic Sites

Comparative review of the catalytic performance of isolated tetravalent metals as Lewis acid sites in zeolite and MOF materials.

scholarly journals Solid Acids for the Reaction of Bioderived Alcohols into Ethers for Fuel Applications

Catalysts ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 172 ◽  
Author(s):  
Federica Zaccheria ◽  
Nicola Scotti ◽  
Nicoletta Ravasio
Keyword(s):  
Physical Properties ◽  
Lignocellulosic Biomass ◽  
Lewis Acid ◽  
Product Distribution ◽  
Acid Sites ◽  
Solid Acids ◽  
Lewis Acid Sites ◽  
Hydroxymethyl Furfural ◽  
Brønsted And Lewis Acid

The use of solids acids in the synthesis of ethers suitable to be used as fuels or fuel additives were reviewed in a critical way. In particular, the role of Brønsted and Lewis acid sites was highlighted to focus on the pivotal role of the acidity nature on the product distribution. Particular emphasis is given to the recently proposed ethers prepared starting from furfural and 5-hydroxymethyl furfural. Thus, they are very promising products that can be derived from lignocellulosic biomass and bioalcohols and possess very interesting chemical and physical properties for their use in the diesel sector.

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