Tetramethylbenzenium radical cations as major active intermediates of methanol-to-olefin conversions over phosphorous-modified HZSM-5 zeolites

2013 ◽  
Vol 299 ◽  
pp. 240-248 ◽  
Author(s):  
Hoi-Gu Jang ◽  
Hyung-Ki Min ◽  
Suk Bong Hong ◽  
Gon Seo
Keyword(s):  
Radical Cations ◽  
Methanol To Olefin ◽  
Active Intermediates

scholarly journals Direct observation of hexamethylbenzenium radical cations generated during zeolite methanol-to-olefin catalysis: an ESR study

2011 ◽  
Vol 47 (33) ◽  
pp. 9498 ◽  
Author(s):  
Sun Jung Kim ◽  
Hoi-Gu Jang ◽  
Jun Kyu Lee ◽  
Hyung-Ki Min ◽  
Suk Bong Hong ◽  
...  
Keyword(s):  
Direct Observation ◽  
Radical Cations ◽  
Methanol To Olefin

Reactivity Trends in the Gas Phase Addition of Acetylene to N-protonated Aryl Radical Cations

2020 ◽  
Author(s):  
Oisin Shiels ◽  
P. D. Kelly ◽  
Cameron C. Bright ◽  
Berwyck L. J. Poad ◽  
Stephen Blanksby ◽  
...  
Keyword(s):  
Gas Phase ◽  
Ion Trap ◽  
Radical Cations ◽  
Rate Coefficients ◽  
Similar Process ◽  
Ion Molecule Reactions ◽  
Aromatic Radicals ◽  
Polycyclic Aromatic ◽  
Gas Phase Ion ◽  
Type Radical

<div> <div> <div> <p>A key step in gas-phase polycyclic aromatic hydrocarbon (PAH) formation involves the addition of acetylene (or other alkyne) to σ-type aromatic radicals, with successive additions yielding more complex PAHs. A similar process can happen for N- containing aromatics. In cold diffuse environments, such as the interstellar medium, rates of radical addition may be enhanced when the σ-type radical is charged. This paper investigates the gas-phase ion-molecule reactions of acetylene with nine aromatic distonic σ-type radical cations derived from pyridinium (Pyr), anilinium (Anl) and benzonitrilium (Bzn) ions. Three isomers are studied in each case (radical sites at the ortho, meta and para positions). Using a room temperature ion trap, second-order rate coefficients, product branching ratios and reaction efficiencies are reported. </p> </div> </div> </div>

Progress in the Research on Methanol-to-Olefin Technology

2011 ◽  
Vol 2 (3) ◽  
pp. 191-199
Author(s):  
Qian Wang ◽  
Zengxi Li ◽  
Lei Wang
Keyword(s):  
Methanol To Olefin

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.

Properties and Reactivity of First and Second Row Hydrides. IV. Interactions Between Hydrides and Their Radical Ions

1993 ◽  
Vol 58 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Rudolf Zahradník
Keyword(s):  
Radical Cations ◽  
Stabilization Energy ◽  
Hydrogen Atom Abstraction ◽  
Type Ii ◽  
Radical Ions ◽  
Reaction Products ◽  
Ion Molecule Reactions ◽  
Heats Of Reaction ◽  
Experimental Values ◽  
Easy Differentiation

The energies and heats of ion-molecule reactions have been calculated (MP4/6-31G**//6-31G** or better level) and compared with the experimental values obtained from the heats of formation. Two main types of reactions have been studied: (i) AHn + AHn+• ↔ AHn+1+ + AHn-1• (A = C to F and Si to Cl), (ii) AHn + BHm+• ↔ AHn+1+ + BHm-1• or AHn-1+• + BHm+1+ (A and B = C to F). In contrast to (i), processes of type (ii) permit easy differentiation between the proton transfer and hydrogen atom abstraction mechanisms. A third type of interaction involves reactions with radical anions (A = Li to F); comparison was made with analogous processes with radical cations. A brief comment is made about the influence of the level of computational sophistication on the energies and heats of reaction, as well as on the stabilization energy of a hydrogen bonded intermediate, a structure which is similar to that of the reaction products.

Electrostatic effects on ionization equilibria: An MNDO study of proton and hydrogen transfer reactions of 4-fluorobutylamine

1990 ◽  
Vol 55 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Zdeněk Friedl ◽  
Stanislav Böhm
Keyword(s):  
Hydrogen Transfer ◽  
Substituent Effects ◽  
Radical Cations ◽  
Transfer Reactions ◽  
Protonated Forms ◽  
Minor Part ◽  
Bond Strengths ◽  
Ionization Equilibria ◽  
A Minor ◽  
Gas Phase Basicities

The relative enthalpies of proton transfer δ ΔH0and homolytic bond strengths δDH0(B-H+) were calculated by the MNDO method for the sp and ap conformers of 4-flurobutylamine. The data obtained, along with the experimental gas phase basicities, are compared with the values predicted by the electrostatic theory. It is shown that the substituent polar effects FD on the basicities of amines are predominantly due to interactions in their protonated forms (X-B-H+) and/or radical-cations (X-B+.), those in the neutral species (X-B) playing a minor part. A contribution, which is considerably more significant in the sp conformer than in the ap conformer, arises probably also from substituent effects on the homolytic bond strength DH0(B-H+.

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