Electrochemical promotion of CO2 hydrogenation in a monolithic electrochemically promoted reactor (MEPR)

• Published in: Applied catalysis. B, Environmental Vol. 284; p. 119695
• Main Authors: Chatzilias, Christos, Martino, Eftychia, Katsaounis, Alexandros, Vayenas, Constantinos G.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.05.2021
• Subjects: CO2 hydrogenation; EPOC; MEPR; monolithic reactor; monolithic reactor; CO2 hydrogenation; MEPR; EPOC
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2020.119695

[Display omitted] •A monolithic electropromoted reactor (MEPR) with Ru was used for CO2 hydrogenation.•CH4 selectivity is enhanced with positive polarization (up to 92 % at 370 °C).•The maximum yield to methane was 32 % at 370 °C.•The methanation reaction follows electrophobic (or nucleophilic) behavior.•The RWGS reaction exhibits electrophilic (or nucleophobic) behavior. The electrochemical promotion of the CO2 hydrogenation was investigated, using a monolithic electropromoted reactor (MEPR) loaded with nine, connected in parallel, Ru/YSZ/Au electrochemical cells. The study was carried out at ambient pressure and in the temperature range between 220°C and 370°C, using high reactant flowrates (up to 2500 cm3/min) and reducing conditions (PCO2/PH2=1/7). For an intermediate flowrate of 1000 cm3/min, the selectivity to methane (SCH4) was 100 % for temperatures up to 300°C. Further increase in temperature resulted to a decrease in selectivity to methane with a concomitant increase of the corresponding yield (YCH4) due to the higher CO2 conversion. However, the total performance of the reactor, in terms of methane selectivity and yield, was affected significantly under electropromoted conditions. At the maximum studied temperature of 370°C, the unpromoted values of SCH4 and YCH4 were 84 % and 24 % respectively, while O2− supply to the catalytic surface enhanced theses values to 92 % and 32 % respectively. The qualitative features of electropromotion, i.e. electrophobic behavior for methanation and electrophilic behavior for the RWGS reaction, were in agreement with previous EPOC studies of CO2 hydrogenation in laboratory scale reactors showing a successful scale up of Electrochemical Promotion of Catalysis (EPOC). In addition, the good performance of the monolithic reactor under severe operating conditions of high flowrates and temperatures is a promising result for further scale-up and for the practical utilization of EPOC.