Role of naphthalene during the induction period of methanol conversion on HZSM-5 zeolite

2016 ◽  
Vol 6 (11) ◽  
pp. 3737-3744 ◽  
Author(s):  
Liang Qi ◽  
Jinzhe Li ◽  
Yingxu Wei ◽  
Lei Xu ◽  
Zhongmin Liu
Keyword(s):  
Induction Period ◽  
Methanol Conversion ◽  
Lower Activity ◽  
Zeolite P

Despite the lower activity of naphthalene compared with that of methylbenzenes, its activity was also proved over an HZSM-5 catalyst.

Direct observation of methylcyclopentenyl cations (MCP+) and olefin generation in methanol conversion over TON zeolite

2016 ◽  
Vol 6 (1) ◽  
pp. 89-97 ◽  
Author(s):  
Jinbang Wang ◽  
Yingxu Wei ◽  
Jinzhe Li ◽  
Shutao Xu ◽  
Wenna Zhang ◽  
...  
Keyword(s):  
Induction Period ◽  
Direct Observation ◽  
Methanol Conversion ◽  
Hydrocarbon Pool ◽  
Zeolite P ◽  
First Time

An induction period and MCP+ formed in the methanol conversion have been observed successfully for the first time, indicating that the hydrocarbon pool (HCP) mechanism cannot be ruled out over H-ZSM-22.

Fibrin Formation: The Role of the Fibrinogen-Fibrin Monomer Complex

1976 ◽  
Vol 36 (01) ◽  
pp. 037-048 ◽  
Author(s):  
Eric P. Brass ◽  
Walter B. Forman ◽  
Robert V. Edwards ◽  
Olgierd Lindan
Keyword(s):  
Particle Size ◽  
Induction Period ◽  
Fibrin Clot ◽  
Clot Formation ◽  
Appreciable Amount ◽  
Buffer System ◽  
Homeostatic Mechanism ◽  
Fibrin Formation ◽  
Fibrin Monomer

SummaryThe process of fibrin formation using highly purified fibrinogen and thrombin was studied using laser fluctuation spectroscopy, a method that rapidly determines particle size in a solution. Two periods in fibrin clot formation were noted: an induction period during which no fibrin polymerization occurred and a period of rapid increase in particle size. Direct measurement of fibrin monomer polymerization and fibrinopeptide release showed no evidence of an induction period. These observations were best explained by a kinetic model for fibrin clot formation incorporating a reversible fibrinogen-fibrin monomer complex. In this model, the complex serves as a buffer system during the earliest phase of fibrin formation. This prevents the accumulation of free polymerizable fibrin monomer until an appreciable amount of fibrinogen has reacted with thrombin, at which point the fibrin monomer level rises rapidly and polymerization proceeds. Clinically, the complex may be a homeostatic mechanism preventing pathological clotting during periods of elevated fibrinogen.

scholarly journals Critical role of formaldehyde during methanol conversion to hydrocarbons

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Yue Liu ◽  
Felix M. Kirchberger ◽  
Sebastian Müller ◽  
Moritz Eder ◽  
Markus Tonigold ◽  
...  
Keyword(s):  
Critical Role ◽  
Methanol Conversion

The role of formaldehyde in the oxidation of ethylene

1952 ◽  
Vol 212 (1110) ◽  
pp. 291-311 ◽  
Keyword(s):  
Activation Energy ◽  
Ethylene Oxide ◽  
Induction Period ◽  
Maximum Rate ◽  
Reaction Scheme ◽  
Stationary Concentration ◽  
Rate Of Reaction ◽  
A Minor ◽  
Close Parallelism

The oxidation of ethylene at temperatures in the region of 400° C has been studied manometrically and analytically, and compared with the oxidation of formaldehyde under similar conditions. The observations of previous authors have been confirmed and extended with particular reference to the factors controlling the maximum rate of reaction. The oxidation of ethylene is closely dependent on the development of formaldehyde, which shows the behaviour to be expected of an agent for degenerate branching. There is a close parallelism between the variation of the activation energy of the oxidation of ethylene from 25 kcal at 350° C to 53 kcal at 550° C and of formaldehyde from 21 kcal at 350° C to more than 40 kcal at 500° C. Formaldehyde is produced in the oxidation of ethylene and attains a maximum concentration which is proportional to the ethylene pressure and independent of the oxygen pressure. The addition of formaldehyde to the reaction mixture reduces or removes the induction period without affecting the maximum rate of the reaction. Ethylene oxide plays a minor but significant part; it attains a stationary concentration in the reaction but is less effective than formaldehyde in reducing the induction period. A reaction scheme based on that proposed by Axford & Norrish (1948) for the oxidation of formaldehyde has been developed; it accounts satisfactorily for the observed facts.

The role of outer surface/inner bulk Brønsted acidic sites in the adsorption of a large basic molecule (simazine) on H-Y zeolite

2015 ◽  
Vol 17 (43) ◽  
pp. 28950-28957 ◽  
Author(s):  
Filomena Sannino ◽  
Michele Pansini ◽  
Antonello Marocco ◽  
Barbara Bonelli ◽  
Edoardo Garrone ◽  
...  
Keyword(s):  
Surface Properties ◽  
Outer Surface ◽  
Y Zeolite ◽  
System P ◽  
Acidic Sites ◽  
Zeolite P ◽  
Solid System

Interesting information on the surface properties of a most studied system, zeolite H-Y, is derived from the adsorption of simazine on a liquid/solid system.

Evolution of the reaction mechanism during the MTH induction period over the 2-dimensional FER zeolite

RSC Advances ◽  
2016 ◽  
Vol 6 (61) ◽  
pp. 56698-56704 ◽  
Author(s):  
Liang Qi ◽  
Jinzhe Li ◽  
Lei Xu ◽  
Zhongmin Liu
Keyword(s):  
Reaction Mechanism ◽  
Induction Period ◽  
Dual Cycle ◽  
Zeolite P

During the MTH reaction over HZSM-35, the dual-cycle mechanism was found to evolve evidently as the induction reaction progressed.

The gaseous oxidation of aliphatic alcohols. I. Ethyl alcohol: the products formed in the early stages

1956 ◽  
Vol 237 (1211) ◽  
pp. 530-542 ◽  
Keyword(s):  
Hydrogen Peroxide ◽  
Induction Period ◽  
Ethyl Alcohol ◽  
Critical Concentration ◽  
Volume Ratio ◽  
Analytical Investigation ◽  
Moderate Increase ◽  
Early Stages ◽  
Low Pressures

A detailed analytical investigation has been made of the reactions occurring during the early stages of the oxidation of ethyl alcohol (ethanol) in the temperature region 270 to 370° C. During an induction period the alcohol is converted quantitatively into acetaldehyde until a critical concentration of this intermediate has accumulated. The pressure then begins to rise autocatalytically, and methanol, formaldehyde and carbon monoxide become detectable; evidence is presented to show that these compounds arise from the further oxidation of acetaldehyde. The amount of ethanol consumed and of acetaldehyde formed at the end of the induction period are largely independent of the initial reactant pressures, except at low pressures of the alcohol. A study of the effect of added acetaldehyde shows that the minimum quantity required to eliminate the induction period is the same as that normally present at the end of the induction period. Hydrogen peroxide is the only product, other than acetaldehyde, detected during the induction period. Under optimum surface conditions the yields of hydrogen peroxide are equivalent to those of the aldehyde. A moderate increase in surface shortens the induction period, but a further increase retards reaction. In vessels of large surface: volume ratio, the yields of hydrogen peroxide are much reduced, while in a potassium chloride-coated vessel peroxides are invariably absent; in each case, the other products are unchanged. The mechanisms of the chain-initiating and propagating reactions are considered and the role of the surface in initiating and terminating chains is discussed.

scholarly journals The dual role of palladium in enhancing the photocatalytic activity of CdS dispersed on NaY-zeolite

2015 ◽  
Vol 17 (10) ◽  
pp. 6896-6904 ◽  
Author(s):  
R. Sasikala ◽  
A. P. Gaikwad ◽  
V. Sudarsan ◽  
R. Rao ◽  
Jagannath Jagannath ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Dual Role ◽  
Nay Zeolite ◽  
Co Catalyst ◽  
Zeolite P

A stable photocatalyst, CdS dispersed on zeolite with Pd as both dopant and co-catalyst, exhibits enhanced photocatalytic activity.

ChemInform Abstract: ROLE OF ACID PROPERTY OF VARIOUS ZEOLITES IN THE METHANOL CONVERSION TO HYDROCARBONS

1984 ◽  
Vol 15 (17) ◽  
Author(s):  
H. ITOH ◽  
C. V. HIDALGO ◽  
T. HATTORI ◽  
M. NIWA ◽  
Y. MURAKAMI
Keyword(s):  
Methanol Conversion ◽  
Acid Property

Comparison of dual and single spark ignition in operation of a large piston aircraft engine

2020 ◽  
pp. 146808742096096
Author(s):  
Jacek Czarnigowski ◽  
Piotr Jakliński ◽  
Paweł Karpiński
Keyword(s):  
Induction Period ◽  
Engine Speed ◽  
Combustion Process ◽  
Aircraft Engine ◽  
Leading Role ◽  
Spark Plug ◽  
Combustion Processes ◽  
Large Piston ◽  
Similar Intensity

The paper presents the results of the experimental research on the combustion process inside the cylinder of a large piston radial aircraft engine with dual or single spark plug ignition. The tests were carried out on the ASz-62IR-16X radial engine equipped with a double, electronically controlled ignition system with two spark plugs in each cylinder. The constant engine speed tests allowed for comparing the combustion processes with ignition carried out by both spark plugs, the rear plug only, and the front plug only. The analyses were based on the recorded pressure signal from one of the engine cylinders. It has been shown that the type of ignition significantly affects the combustion process and its non-repeatability. The obtained results indicate the leading role of the rear spark plug in initiating the combustion process. When the ignition is carried out with the rear spark plug, the induction period is identical to that for dual ignition, but the combustion process is much less intensive. Ignition carried out with the front spark plug only has a longer induction period but a similar intensity of combustion as with dual ignition. Deactivating one of the plugs also improves the non-repeatability of the combustion process.

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