Adsorption and activation of ethene by zeolite-H-ZSM-5

Abstract

Thermogravimetric adsorption data for CzH4 and H 2 0 and i.r. and n.m.r. spectroscopic results are combined to obtain information on the role played by acidic Bronsted sites in the H-ZSM-5 zeolite in the adsorption and activation of C2H4. Water and ethene compete for such sites in various ways which depend on the pretreatment of the zeolite. Physisorbed water prevents the adsorption of C2H4. Ethene is readily activated and reacts on the Bronsted acidic sites, even at room temperature. There is further evidence for the formation of carbenium-type intermediates.

Alkylphenols to phenol and olefins by zeolite catalysis: a pathway to valorize raw and fossilized lignocellulose

“…66 On another account, effects have been attributed to confinement effects or nest effects caused by water within the zeolite pores. 51 Conversely, water could also act as a sweeping agent, forcing formed products to diffuse away from the zeolite, 67 and rendering the role of water to be mostly adsorptive, hence physical, rather than chemical. However, clear evidence of the role of water has thus far remained absent.…”

Influences of Brönsted Acidic Sites in H[Al]ZSM‐5 on Polarization and Electronegativity of Ethene Studied by Molecular Dynamics

“…The electrostatic interactions were represented by a shielded potential [ Vsh ( R ) ] shown in Eq. (3) .' The parameter yi was cornputed as the geometric m a n of atomic parameters ( yi , rj).…”

“…axis coordinate(MI) b axis coordinate(MI) b axis coordinate(nm) FQ 3. Dependence of molecular dipole moment and elecmnegativity on molecular position in the four straight channels of the framework of the simulation box.…”

Raman spectroscopic studies on the molecular reorientation and vibrational relaxation in liquid ethylene

“…We believe the time has come when this sort of work needs to be applied to problems of real chemical interest. As part of a project aimed at the detailed study of the molecular dynamics of ethylene adsorbed on zeolite surfaces [6,7,10] we have made a detailed study of the reorientational and vibrational relaxation of ethylene molecules in the pure liquid phase. This will enable us to compare the dynamics of adsorbed ethylene with those in the ' free' (liquid) molecule, and will give us direct information about the mobility and interactions of the chemisorbed molecule, Ethylene is in some ways a very easy molecule to examine using the Raman band shape technique [13,14].…”

“…The interaction of ethylene at metal centres [1][2][3][4][5][6][7][8][9], especially on catalytic materials [1,[4][5][6][7][8][9][10], is of considerable interest from both fundamental [2,3,7] and technological [4,6,10] points of view. The determination of molecular interactions using the dynamic properties [11,12] of a molecule in different environments is by now well-established but it has only rarely been applied to systems of industrial importance or indeed to metal complexes [1,6,8,9].…”