Rational design of metal–ligands for the conversion of CH₄ and CO₂ to acetates: role of acids and Lewis acids

Abstract

<p>The capturing, sequestration and utilization of carbon dioxide have attracted global attention in environment, science and industry. The concurrent conversion of CO2 and CH4 is a reasonable solution to reduce...</p>

Rational Design of Metal-Alkoxide-Functionalized Metal–Organic Frameworks for Synergistic Dual Activation of CH4 and CO2 toward Acetic Acid Synthesis

“…In the past decades, both homogeneous and heterogeneous catalysts have been explored to promote this conversion. A few reported homogeneous catalysts are mainly metal complexes such as the Pd complex, the V complex, and the half-sandwich metal (Ru, Rh, and Ir) complexes . Comparatively, there has been more progress in the design of heterogeneous catalysts including metals, metal oxides, and metal-modified zeolites for this conversion.…”

“…In view of this, substantial efforts have been devoted to searching and constructing efficient catalytic active sites capable of facilitating C–C coupling. For example, Bhaskararao et al computationally designed bifunctional half-sandwich metal (Ru, Rh, and Ir) complexes via exploiting metal–ligand synergy to achieve efficient C–C coupling . By combining experiment and theory, Nie et al claimed a strong synergy in Fe/ZnO, which is responsible for accelerated CH 4 dissociation and C–C coupling .…”

“…Bearing this in mind, in this work, we computationally design new dual-site MOF catalysts by introducing metal-alkoxide to a parent MOF (UiO-67) and rationalize their catalytic reactivity for concurrent conversion of CH 4 and CO 2 into acetic acid. The choice of metal-alkoxide to functionalize UiO-67 is because the metal–oxygen pair within single metal-alkoxide resembles the active sites of reported homogeneous complexes, metal oxides, and zeolites for this reaction. ,,,, In addition, metal-alkoxide-functionalized MOFs have been experimentally synthesized and computationally explored for CO 2 capture, , H 2 adsorption, N 2 /CH 4 separation, and CO 2 hydrogenation to HCOOH …”

Density Functional Theory Study on [Ni0(1,10-Phenanthroline)]-Catalyzed Reductive Carboxylation of Alkyl and Aryl Halides with CO2: Effect of the Lewis Acid and β-H Elimination Side Reaction in the Crucial CO2 Insertion Step

“…20,28,43 Except in few studies, the role of additives is not well established. 20 Herein, the effect of Lewis acids (additives), viz., X = MgCl 2 , ZnCl 2 , AlCl 3 , and LiCl, has been investigated in the CO 2 insertion of Ni I (5, Figures S4−S7) and Ni II (7, Figures S8−S11) propyl chlorides, whereas the effect of the Lewis acid is not considered in the analogous phenyl chloride as the Ni I -mediated CO 2 insertion (ΔG ⧧ of +0.9 kcal/mol, Scheme 5a) is rapid in the absence of the Lewis acid itself. In the case of [Ni I (phen)(R′-CH 2 )-(CO 2 )] ( 5) and [Ni II (phen)(R′-CH 2 )(Cl)(CO 2 )] ( 7), the Lewis acid (X) is coordinated with one of the oxygen atoms (O2) of the CO 2 molecule via the cationic counterpart (viz., Mg 2+ , Zn 2+ , Al 3+ , and Li + ) and leads to the adducts 5-X and 7-X, respectively (see Figure 5).…”

“…The role of Lewis acids in enhancing CO 2 activation is further supported by the density functional theory (DFT) study in the case of bifunctional half-sandwich Ru, Rh, and Ir complexes. 20 Similarly, the kinetics study on the CO 2 insertion into the Ru−H bond of [Ru(tpy)bpy)H]PF 6 revealed the enhancement in the rate of the reaction in the presence of Lewis acids. 21 However, there is no concrete evidence so far established in the literature to elucidate the role of additives used in the reductive carboxylation of aryl/alkyl halides.…”