Pd/C‐catalyzed reduction of NaHCO₃ into formate with 2‐pyrrolidone under hydrothermal conditions

Abstract

Conversion of CO2 into useful chemicals has been regarded as one promising method to mitigate the problem of global warming. However, developing an efficient method for CO2 reduction with facile hydrogen source is still a great challenge. In this study, a new and straightforward method to convert NaHCO3, a model compound of CO2 in basic solution, into formate with 2‐pyrrolidone, a model compound of protein‐containing biomass, as the reductant on a Pd/C catalyst in water was proposed. Results showed that a formate yield up to 30% from bicarbonate was successfully obtained over the Pd/C catalyst, and the Pd/C catalyst exhibited good catalytic activity and stability. Detailed studies revealed that the propanol generated from the decomposition of 2‐pyrrolidone under hydrothermal conditions acted as the actual reductant and hydrogen source for the bicarbonate reduction to formate. Since 2‐pyrrolidone can be readily generated from the proteins contained in biomass, the present research provides a promising technology of NaHCO3 reduction with biomass as the hydrogen source and the renewable energy input, thus it is green, sustainable, and promising for practical application.

Hydrothermal Reduction of NaHCO3 into Formate with Protein-Based Biomass over Pd/γ-Al2O3 Nanocatalysts

“…Subsequently, the formed NO 2 – interacts with NH 4 + , which is hydrolyzed from the amino acid (path (a)), to obtain stable N 2 and H 2 O, while amino acid is converted to alcohols (in the case of l -alanine, it was converted to ethanol). In the meantime, the processes of NaHCO 3 hydrogenation take place over the surface of the catalyst, where *H is adsorbed on the reactive-metal Pd and *HCO 3 – is adsorbed on the support γ-Al 2 O 3 and then following the rule of the SN 2 -like mechanism, NaHCO 3 is reduced to formate. , The total reactions are summarized in eqs –. Subsequently, a thermodynamic assessment of the alanine reaction with NaHCO 3 was performed, as shown in eq .…”

“…In the meantime, the processes of NaHCO 3 hydrogenation take place over the surface of the catalyst, where *H is adsorbed on the reactive-metal Pd and *HCO 3 − is adsorbed on the support γ-Al 2 O 3 and then following the rule of the SN 2 -like mechanism, NaHCO 3 is reduced to formate. 9,39 The total reactions are summarized in eqs 3−5. Subsequently, a thermodynamic assessment of the alanine reaction with NaHCO 3 was performed, as shown in eq 6.…”

CO2 reduction into formic acid under hydrothermal conditions: A mini review

“…69 By contrast, in the hydrothermal CO 2 reduction, metal catalysts including Cu, Pd/C, Pd 0.5 Cu 0.5 /C and Ni displayed relatively high stability, during which the fluctuation of formic acid yield is less than 5% after 3−5 times recovery for all the tested metals, as shown in Figure 11. More specifically, Cu and Pd/C maintained their activity F I G U R E 1 0 (A) Distribution of carbonaceous species in water solution at different pH 66 ; (B) effect of the starting pH on the formic acid production 25,30,32 ; (C) effect of the initial amount of HCO 3 − on the production of formic acid at 300°C and 2-h condition, 25,65 and the catalytic activity for bimetallic catalyst Pd 0.5 Cu 0.5 /C was still kept after for 5 times reused times at 180°C for even 16 h. 14 Additionally, scanning electron microscope (SEM) and XRD results showed the morphology and crystallinity of reused catalyst had no obvious change after the reaction, while only a slight content of aggregation of metal particles was observed by TEM characterization, further indicating the relative stability of catalyst for hydrothermal CO 2 reduction.…”

“…(A) Distribution of carbonaceous species in water solution at different pH 66 ; (B) effect of the starting pH on the formic acid production 25,30,32 ; (C) effect of the initial amount of HCO 3 − on the production of formic acid 15,62,65,67 …”

“Reverse combustion” of carbon dioxide in water: The influence of reaction conditions

“…Many methods such as catalytic hydrogenation, or electrochemical or photochemical reactions have been proposed for the direct conversion of CO 2 . However, photochemical and electrochemical reduction of CO 2 present a low efficiency, thereby limiting their application (Zhu et al, 2019). Although catalytic hydrogenation of CO 2 has arisen as a promising and feasible technique for CO 2 utilisation, it typically requires the addition of gas-phase hydrogen (Zhong et al, 2019a).…”