Low‐Temperature Reverse Water–Gas Shift Process and Transformation of Renewable Carbon Resources to Value‐Added Chemicals

Abstract

The use of CO2 instead of toxic CO in the production of important chemicals has attracted widespread interest, and the reverse water–gas shift reaction (RWGSR) is the key step for this kind of processes. Although the thermodynamic limitations are overcome by the reaction of CO with other compounds, the temperature of most reactions involving RWGSR is usually very high owing to the inertness of CO2. Herein, it was found that Ru3(CO)12 could catalyze the RWGSR in the ionic liquid HMimBF4 without ligand or promoter, and CO could be produced at 80 °C, which was much lower than the temperatures reported to date. Detailed studies showed that the BF4− in the ionic liquid played a crucial role in the low‐temperature RWGSR. Based on the low‐temperature RWGSR, three important routes to transform CO2 into valuable chemicals were developed, including synthesis of xanthone from CO2 and diaryl ethers, synthesis of phenol and acetic acid from CO2 and anisole, and production of acetic acid from CO2 and lignin. The reactions could occur at temperature as low as 80 °C, and low‐temperature RWGSR was essential for the reactions under mild conditions. The strategy opens the way to produce value‐added chemicals by using CO2 and H2 as feedstocks under low temperature.

Catalytic self-transfer hydrogenolysis of lignin with endogenous hydrogen: road to the carbon-neutral future

“…There have been only a few reports on utilizing methoxy groups in lignin into valuable chemicals. 45,46 In fact, the methoxy groups in lignin can be regarded as the methanol derivative, which provided the hydrogen source via dehydrogenation or aqueous phase reforming for the self-transfer hydrogenolysis of lignin. Compared to the aliphatic hydroxy group in the side group of lignin, the methoxy group in lignin can supply more H 2 for the hydrogenolysis and upgradation of lignin.…”

Product‐oriented Direct Cleavage of Chemical Linkages in Lignin

“…More importantly, acetic acid is the single liquid product and the residual lignin, which is abundant in hydroxyl groups, is more favorable for utilization in certain applications than original lignin, such as the synthesis of functional materials. The toxic CO can be replaced by CO 2 in the synthesis of acetic acid and the reverse water‐gas shift reaction (RWGSR) is the critical step for this process . In addition, LiI combined with Ru−Co bimetal catalytic system could catalyze the reaction between methoxy groups of lignin and CO 2 to produce ethanol …”

K-Promoted Ni-Based Catalysts for Gas-Phase CO2 Conversion: Catalysts Design and Process Modelling Validation

“…The design of highly efficient catalysts able to achieve low-temperature RWGS and to be highly selectivity to the desired product under mild conditions is the key to the production of important chemicals with CO 2 through RWGS coupled with other reactions (for example, FT). ( Shen et al, 2019 ; Yang et al, 2020 ) The selectivity to CO at low temperature is one of the main drawbacks of the RWGS reaction. From thermodynamics perspective, it is evident that the production of CH 4 is highly favoured at low temperature.…”