Direct Synthesis of Methyl Formate from CO₂ With Phosphine‐Based Polymer‐Bound Ru Catalysts

Abstract

Methyl formate was produced in one pot through the hydrogenation of CO2 to formic acid/formate followed by an esterification step. The route offers the possibility to integrate renewable energy into the fossil‐based chemical value chain. In this work, a phosphine‐polymer‐anchored Ru complex was shown to be an efficient solid catalyst for the direct hydrogenation of CO2 to methyl formate. The 1,2‐bis(diphenylphosphino)ethane‐like polymer presented the highest activity with a turnover number (TON) of up to 3401 at 160 °C. The reaction parameters were systemically investigated to optimize the reaction towards the formation of methyl formate. This catalyst could be reused seven times without a significant decrease in activity. Evolution of the catalytic Ru center during the reaction was revealed, and a possible reaction mechanism was proposed.

Heterogeneous catalysts for CO2hydrogenation to formic acid/formate: from nanoscale to single atom

“…For example, the group of Palkovits has designed a polymeric analogue of diphenylphosphine (pDPPE) by the cross coupling of corresponding organic linkers and phosphorus salts. 161,162 The obtained phosphine-based pDPPE polymer served as a perfect solid ligand to fabricate heterogeneous molecular Ru(II) catalysts, wherein each Ru(II) center was proposed to coordinate to two P donors (Scheme 5). The absence of Ru particles indicated the atomically-dispersed and well-coordinated structures of Ru species on pDPPE.…”

“…Thus, the actual configuration of Ir@AP-POP taking part in the catalytic process comprises two hydride species and one hydroxyl ligand bonded to Ir center. As such, the in situ substitution of chloride ligand by other species (mostly hydride) is a common phenomenon for immobilized molecular catalysts, also occurring for Ru@pDPPE, 162 RuCl@bpy-CTF, 149 and IrCl@PN-PEI-TNT-Na. 167 The catalytic cycle starts with CO 2 adsorption onto Ir−hydride to trigger the nucleophilic attack of hydride to the carbon atom in CO 2 (see i to ii in Figure 29).…”

Biofuel purification: Coupling experimental and theoretical investigations for efficient separation of phenol from aromatics by zeolites

“…The increase in the global energy consumption through the use of fossil fuels is expected to have harmful consequences, such as the emission of greenhouse gases known to be the main drivers of climate change. [1][2][3][4][5] For such reason, concerns are raised for the development of clean and renewable derivatives and energy sources. [6][7][8] Among the possible renewable energy sources, biomass, and especially lignocellulosic biomass, presents the unique potential of providing liquid biofuels that can replace fossil fuels.…”

Formic acid as H2storage system: hydrogenation of CO2and decomposition of formic acid by solid molecular phosphine catalysts

“…The conversion of CO 2 to methyl formate in NEt 3 /MeOH was recently published by our group. 18 The aprotic solvents (DMF, THF, DMSO, MeCN) show very low activities with TONs less than 1000. This signifies that activity is strongly dependent on the solvents ability to form hydrogen bonds.…”

“…17 In our previous studies, Ru immobilized on various novel polyphosphines proved to be active and selective in the CO 2 hydrogenation and subsequent esterification to methyl formate in methanol. 18 The hydrogenation of CO 2 to FA − in the presence of a series of inorganic bases was also studied and a TON of 13 170 obtained. 19 However, the high amount of FA − salt in the reaction medium precipitated and partially enclosed the catalyst.…”