Use of a dispersed iron catalyst for upgrading extra-heavy crude oil using methane as source of hydrogen☆

Theoretical Study on the Potential Energy Surface of Decarbonylation of the Acetaldehyde by Ni2+

“…The CH 4 and CO loss by Ni 2+ proceeds through four elementary steps, i.e., encounter complexation, C-C activation, H-shift and nonreactive dissociation, and the third step of the process constitutes the rate-determining step. The stable precursor of the decarbonylation products CH 4 and Ni 2+ (CO) has a structure of (CH 4 ) Ni 2+ (CO) rather than (CH 3 )H Ni 2+ CO). The decarbonylation of CH 3 CHO with Ni +2 follows C-C activation rather than aldehyde C-H activation.…”

“…In contrast to the traditional suggestion that the rate-determining step is initial C-C insertion. TS2 is found to be the most demanding point along the whole CH 4 and CO elimination pathway, the energy is higher 24.7 kcal/mol than the initial C-C activation transition state and 13.5 kcal/mol than the separated reactants. Therefore, on the basis of the B3LYP calculations, TS2 is in fact the rate-determining tight transition state of the CH 4 and CO elimination.…”

“…2+ center interacts with these atoms closely. Although the transition state TSl is the first saddle between the intermediate M1 and M2, the bond distance is closed to the M2, so it is the late transition state of potential energy surface, from the bond distance and the angle, it can be seen that TS1 has an overall Cs symmetry with the symmetry plane defined by 1 Ni- 4 O-2 C-5 C, This transition state is expected to be stabilized to some extent by an agnostic interaction between the 2C -H1 bond and the Ni 2+ center as evident by the stretched bond length of 2 C-5 C, As a consequence, it lies below the entrance channel by 11.2 kcal/mol, which translates into an energy barrier of 37.1 kcal/mol with respect to M1. Figure.2 the diagram of relative energies along the channels for the decarbonylation Transition state TS2 connects M2 and products, which was carefully confirmed by IRC calculations.…”

“…In this field, understanding the mechanisms of C-C and C-H activation of decarbonylation by transition metal ions are of particular interest. Researchers made a significant efforts the concerning these aspects [1][2][3][4][5][6][7] . Many experimental techniques have been used to study the mechanism of the bond activation of decarbonylation by transition metal ions.…”

Upgrading vacuum residuum by combined sonication and treatment with a hydrogen donor

“…Use of hydrogen donors has been proposed for upgrading heavy oils and natural bitumens during aquathermolysis and pyrolysis: cyclohexane, methylcyclohexane, tetralin [1, [14][15][16][17]. The hydrogen donor forms hydrogen free radicals, which react with radicals in the crude [15,16], leading to viscosity reduction in the products as a result of blocking polymerization reactions.…”