Poly(ethyleneimine)‐Mediated Consecutive Hydrogenation of Carbon Dioxide to Methanol with Ru Catalysts

Abstract

The utilization of polymeric amines for the hydrogenation of CO 2 to methanol via formamides was explored with a focus on a catalytic promoter, as well as a beneficial reaction medium with enhanced basicity. Branched and linear poly(ethyleneimine)s (PEIs) were efficiently formylated in the presence of a series of PN H P-pincer Ru complexes under CO 2 hydrogenation conditions at 100°C in THF. The obtained Nformylated PEI was characterized by NMR spectroscopy. The formamide units on the polymer were reduced at a higher temperature under pressurized H 2 to afford methanol and to recover [a]

Integrated CO2 Capture and Conversion to Formate and Methanol: Connecting Two Threads

“…Thus, the unique ability of C-1 and C-4 to provide methanol with high catalytic efficiency is due to the lability of the carbonyl ligand, which allows the formation of catalytically active dihydride species. Other structural features such as the spectator ligand do not influence the methanol yield to the same extent (as in the case of catalyst C-8 ). , …”

Hydrogenation of CO2 or CO2 Derivatives to Methanol under Molecular Catalysis: A Review

“…Several new catalyst systems containing ruthenium and amine auxiliaries were investigated, and an exceptional TON of 8900 and TOF of 4500 h Another amine-assisted CO2 hydrogenation to methanol without a tridentate pincertype ligand was reported by the Wass group in 2017 (Figure 9) [53]. Several new catalyst systems containing ruthenium and amine auxiliaries were investigated, and an exceptional TON of 8900 and TOF of 4500 h −1 were obtained by employing [RuCl2(Ph2PCH2CH2NHMe)2] ([Ru]-8) and diisopropylamine under 100 °C in 2 h. In addition to small molecular organic amines and inorganic bases promoting CO2 hydrogenation, polymeric amines with a molecular weight ranging from 600 to 250,000 were investigated by Kayaki and their coworkers in 2019 [54]. Branched and linear poly(ethyleneimine)s (PEIs) were used as an amine source to be formylated, with the [Ru]-4 catalyst at 100 °C in THF.…”

“…A variety of substituted methyl carbamates as substrates were also able to be hydrogenated with [Ru]-2 under 10 bar H2 at 110 °C in THF, to deliver methanol in 94-98% yield. In addition to small molecular organic amines and inorganic bases promoting CO 2 hydrogenation, polymeric amines with a molecular weight ranging from 600 to 250,000 were investigated by Kayaki and their coworkers in 2019 [54]. Branched and linear poly(ethyleneimine)s (PEIs) were used as an amine source to be formylated, with the [Ru]-4 catalyst at 100 • C in THF.…”

Suppressing Dormant Ru States in the Presence of Conventional Metal Oxides Promotes the Ru-MACHO-BH-Catalyzed Integration of CO2 Capture and Hydrogenation to Methanol

“…Among various proposed CCU processes, CO 2 to methanol conversion attracts intensive interests both from academia and industry as methanol can be used as decentralized energy storage and as alternative bulk chemical industry feedstock (methanol economy). − In this context, Guan and others successfully demonstrated CO 2 reduction to methanol despite the need of expensive silanes , or boranes. − Importantly, hydrogenation technology using renewable H 2 is feasible and appealing in large methanol production plants. However, despite being applied in many countries, traditional heterogeneous hydrogenation catalysts to convert CO 2 to methanol require harsh process conditions, i.e., high temperatures (>220 °C) and pressures, resulting in poor selectivity, low theoretical yields, fast catalyst deactivation, safety issues, and high capital investment. − Given these disadvantages, developing mild and efficient CO 2 hydrogenation to methanol catalysts, preferably based on heterogeneous and homogeneous catalysis, has recently attracted a lot of attention. − Among these reported catalysis systems, M/NH − bifunctional and triphos − -based molecular catalysts display attractive hydrogenation activity and productivity. In particular, M/NH bifunctional molecular catalysts allow the cooperation of amine additives, offering significant benefits in integrating the capture and conversion of CO 2 and thus, in particular, the direct utilization of CO 2 -rich amine solutions instead of gas.…”

“…In contrast, integrating catalytic systems preferring acidic conditions such as triphos-based catalysts with CO 2 capturing may be unlikely. Recent advancements in M/NH bifunctional molecular catalysts are pertinent and merely focus on lowering the rate determination transition state barriers and developing more suitable amine additives. − Among the molecular catalysts, Ru-MACHO-BH proves to be one of the most active homogeneous systems and is able to integrate CO 2 capture and hydrogenation to methanol in the presence of polyamine additives under mild conditions. ,,,,, …”