scholarly journals A review on catalytic methane combustion at low temperatures: Catalysts, mechanisms, reaction conditions and reactor designs

2020 ◽  
Vol 119 ◽  
pp. 109589 ◽  
Author(s):  
Li He ◽  
Yilin Fan ◽  
Jérôme Bellettre ◽  
Jun Yue ◽  
Lingai Luo
Keyword(s):  
Low Temperatures ◽  
Methane Combustion ◽  
Reaction Conditions

scholarly journals Improvement of Methane Combustion Activity for Pd/ZrO2 Catalyst by Simple Reduction/Reoxidation Treatment

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 838 ◽  
Author(s):  
Chansong Kim ◽  
Eunpyo Hong ◽  
Chae-Ho Shin
Keyword(s):  
Catalytic Activity ◽  
Low Temperatures ◽  
Methane Combustion ◽  
Reduction Temperature ◽  
Isothermal Reaction ◽  
Ch4 Combustion ◽  
Cyclic Temperature ◽  
Zro2 Catalyst ◽  
Number Of Cycles ◽  
Simple Reduction

The improvement of methane combustion activity was observed in cyclic temperature-programed and isothermal reactions over Pd/ZrO2 catalysts by simple reduction/reoxidation treatment. The catalytic activity increased during the initial stages of isothermal reaction, and the light-off temperature was lowered as the number of cycles increased in the cyclic temperature-programed reaction. To reveal the origin of activation, variations in the reduction properties after the activation period were carefully investigated through CH4 temperature-programed reduction (TPR) measurements. From the CH4-TPR results, it was confirmed that the reduction temperature decreased significantly after activation. The observation of the CH4-TPR peak at relatively low temperatures is directly proportional to the catalytic activity of CH4 combustion. It was therefore concluded that repeated reduction/reoxidation occurred in the reactant stream, and this phenomenon allowed the combustion reaction to proceed more easily at lower temperatures.

Amino acid-promoted Ullmann-type coupling reactions and their applications in organic synthesis

2009 ◽  
Vol 81 (2) ◽  
pp. 227-234 ◽  
Author(s):  
Qian Cai ◽  
Hui Zhang ◽  
Benli Zou ◽  
Xiaoan Xie ◽  
Wei Zhu ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Asymmetric Synthesis ◽  
Organic Synthesis ◽  
Low Temperatures ◽  
Substitution Effect ◽  
Aryl Halides ◽  
Coupling Reactions ◽  
Reaction Conditions ◽  
Type Coupling

Ullmann-type coupling reactions between aryl halides and N-containing reagents, phenols, and other related nucleophilic agents are very valuable transformations for organic synthesis. Their conventional reaction conditions require high reaction temperatures. We describe here that some amino acids, either as substrates or ligands, can lead Cu-catalyzed C-N, C-O, C-S, and C-C bond formations work at relatively low temperatures. An ortho-substitution effect caused by NHCOR groups is discussed. Applications of these newly developed reactions to heterocycle preparation and asymmetric synthesis are also presented.

Simplified Kinetic Model for Thermal Combustion of Lean Methane–Air Mixtures in a Wide Range of Temperatures

2013 ◽  
Vol 11 (1) ◽  
pp. 111-121 ◽  
Author(s):  
Anna Pawlaczyk ◽  
Krzysztof J. Gosiewski
Keyword(s):  
Kinetic Parameters ◽  
Low Temperatures ◽  
Reaction Rate ◽  
Kinetic Studies ◽  
Methane Combustion ◽  
Simulation Studies ◽  
Wide Range ◽  
Rate Calculation ◽  
Thermal Combustion ◽  
Simplified Kinetic Model

Abstract The paper presents results of kinetic studies on thermal methane combustion over honeycomb monoliths. An analysis of the previous experiments [1] has shown that equations proposed there and their kinetic parameters satisfactorily describe kinetics only for relatively low temperatures up to approx. 700°C. The present study corresponds to that related and supplements the previous data with new kinetic parameters obtained in higher temperatures in the reaction zone up to 900°C. A method of the reaction rate calculation for further simulation studies combining the kinetic parameters obtained in both ranges of low (LT) according to Gosiewski et al. [1] and high temperatures (HT) are also presented in the paper.

Effect of different reaction conditions on catalytic activity of La(Mn, Fe)O3+λ catalyst for methane combustion

2019 ◽  
Vol 6 (5) ◽  
pp. 055001 ◽  
Author(s):  
Feifei Miao ◽  
Fanfan Wang ◽  
Dongsen Mao ◽  
Xiaoming Guo ◽  
Jun Yu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Methane Combustion ◽  
Reaction Conditions

Diels-Alder Reactions With Unsaturated Sulfoxides. Reactions of (Z)-3-Phenylsulfinylprop-2-Enoic Acid and Methyl-Ester With Furan, 1,3-Diphenylisobenzofuran and Anthracene

1986 ◽  
Vol 39 (4) ◽  
pp. 575 ◽  
Author(s):  
K Picker ◽  
SM Proust ◽  
DD Ridley
Keyword(s):  
Methyl Ester ◽  
High Temperatures ◽  
Low Temperatures ◽  
Diels Alder ◽  
Enoic Acid ◽  
Reaction Conditions ◽  
Thermal Reactions ◽  
Cis And Trans

Methyl (Z)-3-phenylsulfinylprop-2-enoate undergoes Diels -Alder reactions with furan, 1,3-diphenylisobenzofuran and anthracene but chemical and stereochemical courses of the reactions are very dependent upon reaction conditions. Thus, with furan, cis,endo - and cis,exo - adducts are formed exclusively; with 1,3-diphenylisobenzofuran cis,endo - and cis,exo -adducts are formed at low temperatures, whilst the corresponding trans-adducts are formed upon heating; with anthracene where high temperatures are required for condensation cis- and trans-adducts arise together with products from further thermal reactions.

A New Catalytic Method for Producing Preceramic Polysilazanes

1986 ◽  
Vol 73 ◽  
Author(s):  
Yigal D. Blum ◽  
Richard M. Laine ◽  
Kenneth B. Schwartz ◽  
David J. Rowcliffe ◽  
Robert C. Bening ◽  
...  
Keyword(s):  
Transition Metal ◽  
Carbon Content ◽  
Low Temperatures ◽  
Bond Formation ◽  
Catalytic Method ◽  
Reaction Conditions ◽  
Preceramic Polymers

ABSTRACTA transition metal (e.g., Ru3 (CO)12, Pt/C) catalyzed process for Si-N bond formation is discussed that provides a new route to mono-, oligo-, and polysilazanes. The catalysts function by activating Si-H bonds in the pres-ence of ammonia. Polymeric silazanes can also be produced from oligomers in the presence of ammonia at low temperatures. This method allows us to control or modify the composition of the polysilazane during or after the polymeriza-tion. A variety of polysilazanes were prepared and converted to Si3 N4 with ceramic yields ranging from 55%-85%. By varying the monomers and reaction conditions, we can control the nitrogen and carbon content in the preceramic polymers, which enables us to obtain ceramic products that are primarily Si3N4and simultaneously minimizes the coproduction of SiC and C.

Efficient and Versatile Catalytic Systems for the N-Methylation of Primary Amines with Methanol Catalyzed by N-Heterocyclic Carbene Complexes of Iridium

Synthesis ◽  
2018 ◽  
Vol 50 (23) ◽  
pp. 4617-4626 ◽  
Author(s):  
Ken-ichi Fujita ◽  
Genki Toyooka ◽  
Akiko Tuji
Keyword(s):  
Low Temperatures ◽  
Aromatic Amines ◽  
Catalytic Performance ◽  
Aliphatic Amines ◽  
Primary Amines ◽  
Iridium Complexes ◽  
Reaction Conditions ◽  
Catalytic Systems ◽  
Carbene Complexes ◽  
Amine Compounds

Efficient and versatile catalytic systems were developed for the N-methylation of both aliphatic and aromatic primary amines using methanol as the methylating agent. Iridium complexes bearing an N-heterocyclic carbene (NHC) ligand exhibited high catalytic performance for this type of transformation. For aliphatic amines, selective N,N-dimethylation was achieved at low temperatures (50–90 °C). For aromatic amines, selective N-monomethylation and selective N,N-dimethylation were accomplished by simply changing the reaction conditions (presence or absence of a base with an appropriate catalyst). These findings can be used to develop methods for synthesizing useful amine compounds having N-methyl or N,N-dimethyl moieties.

Undecagold labeling of tRNA

1991 ◽  
Vol 49 ◽  
pp. 44-45
Author(s):  
James F. Hainfeld ◽  
Kyra M. Alford ◽  
Mathias Sprinzl ◽  
Valsan Mandiyan ◽  
Santa J. Tumminia ◽  
...  
Keyword(s):  
High Resolution ◽  
Transmission Electron Micrograph ◽  
Anticodon Loop ◽  
Electron Micrograph ◽  
Reaction Conditions ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

The undecagold (Au11) cluster was used to covalently label tRNA molecules at two specific ribonucleotides, one at position 75, and one at position 32 near the anticodon loop. Two different Au11 derivatives were used, one with a monomaleimide and one with a monoiodacetamide to effect efficient reactions.The first tRNA labeled was yeast tRNAphe which had a 2-thiocytidine (s2C) enzymatically introduced at position 75. This was found to react with the iodoacetamide-Aun derivative (Fig. 1) but not the maleimide-Aun (Fig. 2). Reaction conditions were 37° for 16 hours. Addition of dimethylformamide (DMF) up to 70% made no improvement in the labeling yield. A high resolution scanning transmission electron micrograph (STEM) taken using the darkfield elastically scattered electrons is shown in Fig. 3.

Interpretation of irradiation-induced changes in electron diffractograms and images of extinction contours at low temperatures

1984 ◽  
Vol 42 ◽  
pp. 268-269
Author(s):  
E. Knapek ◽  
H. Formanek ◽  
G. Lefranc ◽  
I. Dietrich
Keyword(s):  
Low Temperatures ◽  
Carbon Films ◽  
Organic Crystals ◽  
Wide Spread ◽  
Lens System ◽  
Preparation Conditions ◽  
Thin Carbon ◽  
Electron Diffractograms ◽  
Diffraction Patterns ◽  
Induced Changes

A few years ago results on cryoprotection of L-valine were reported, where the values of the critical fluence De i.e, the electron exposure which decreases the intensity of the diffraction reflections by a factor e, amounted to the order of 2000 + 1000 e/nm2. In the meantime a discrepancy arose, since several groups published De values between 100 e/nm2 and 1200 e/nm2 /1 - 4/. This disagreement and particularly the wide spread of the results induced us to investigate more thoroughly the behaviour of organic crystals at very low temperatures during electron irradiation.For this purpose large L-valine crystals with homogenuous thickness were deposited on holey carbon films, thin carbon films or Au-coated holey carbon films. These specimens were cooled down to nearly liquid helium temperature in an electron microscope with a superconducting lens system and irradiated with 200 keU-electrons. The progress of radiation damage under different preparation conditions has been observed with series of electron diffraction patterns and direct images of extinction contours.

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