Continuous Hydrogenation of Carbon Dioxide to Formic Acid and Methyl Formate by a Molecular Iridium Complex Stably Heterogenized on a Covalent Triazine Framework

Abstract

Continuous synthesis of formic acid and methyl formate via CO2 hydrogenation is demonstrated using a molecular iridium complex stably immobilized on a solid covalent triazine framework (CTF) under high‐pressure conditions. Compared to formic acid synthesis, methyl formate synthesis is advantageous to enhance the selectivity and yield of formates under kinetically favorable high temperature conditions. Transient in situ vibrational spectroscopy shows that the CTF strongly interacts with CO2 and H2, and even activates methanol. Hence, CTF is a promising support for molecular catalysts, even under harsh supercritical and flow conditions, through its strong binding capability.

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

“…Another study investigated the continuous production of MF with an immobilized Ir(II) complex ([IrCp*Cl 2 ] 2 ) on a 2,6-dicyanopyridinebased CTF (IrCp*@DCP-CTF, Scheme 5). 151 A promising space time yield of 944.4 mg MF g Ir -1 h -1 (corresponding to a TOF of 3 h -1 ) was achieved by feeding a mixed gas stream of CO 2 /H 2 /CH 3 OH into a fixed-bed reactor at 180 °C and 300 bar. By means of transient in situ DRIFTS at 140 °C and 5 bar CO 2 , an intense band at 2334 cm -1 corresponding to the interaction between CO 2 and DCP-CTF was clearly observed, indicating the inherent CO 2 adsorption capability of CTF.…”

Enabling storage and utilization of low-carbon electricity: power to formic acid

“…26). 151 The microporous structure was confirmed by BET measurements (surface area of 734 m 2 g -1 ) and STEM and EDX analyses further indicated the homogeneous dispersion of Ir in the matrix. When the reaction mixture (H2:CO2:S = 4:4:1 molar ratio, S = MeOH, H2O, NEt3) was introduced into the reactor containing 120 at 300 bar at 100 or180 °C, weight time yields of 5.4−385.5 mgFA gIr −1 h −1 were achieved.…”

Immobilization of an Iridium(I)-NHC-Phosphine Catalyst for Hydrogenation Reactions under Batch and Flow Conditions

“…In addition, chemical hydrogen storage is also an environmentally important research topic. Several types of iridium-catalyzed hydrogen storage reactions are known in the literature [28][29][30][31][32][33][34][35][36][37][38][39][40], however, only a few heterogeneously catalyzed, iridium-based hydrogen storage systems have been described recently [41][42][43].…”