5 research outputs found
Optimizing the Performance of Low-Loaded Electrodes for CO2-to-CO Conversion Directly from Capture Medium: A Comprehensive Parameter Analysis
Gas-fed reactors for CO2 reduction processes are a solid technology to mitigate CO2 accumulation in the atmosphere. However, since it is necessary to feed them with a pure CO2 stream, a highly energy-demanding process is required to separate CO2 from the flue gasses. Recently introduced bicarbonate zero-gap flow reactors are a valid solution to integrate carbon capture and valorization, with them being able to convert the CO2 capture medium (i.e., the bicarbonate solution) into added-value chemicals, such as CO, thus avoiding this expensive separation process. We report here a study on the influence of the electrode structure on the performance of a bicarbonate reactor in terms of Faradaic efficiency, activity, and CO2 utilization. In particular, the effect of catalyst mass loading and electrode permeability on bicarbonate electrolysis was investigated by exploiting three commercial carbon supports, and the results obtained were deepened via electrochemical impedance spectroscopy, which is introduced for the first time in the field of bicarbonate electrolyzers. As an outcome of the study, a novel low-loaded silver-based electrode fabricated via the sputtering deposition technique is proposed. The silver mass loading was optimized by increasing it from 116 μg/cm2 to 565 μg/cm2, thereby obtaining an important enhancement in selectivity (from 55% to 77%) and activity, while a further rise to 1.13 mg/cm2 did not provide significant improvements. The tremendous effect of the electrode permeability on activity and proficiency in releasing CO2 from the bicarbonate solution was shown. Hence, an increase in electrode permeability doubled the activity and boosted the production of in situ CO2 by 40%. The optimized Ag-electrode provided Faradaic efficiencies for CO close to 80% at a cell voltage of 3 V and under ambient conditions, with silver loading of 565 μg/cm2, the lowest value ever reported in the literature so far
An Electrochemical Platform for the Carbon Dioxide Capture and Conversion to Syngas
We report on a simple electrochemical system able to capture gaseous carbon dioxide
from a gas mixture and convert it into syngas. The capture/release module is implemented via
regeneration of NaOH and acidification of NaHCO3
inside a four-chamber electrochemical flow
cell employing Pt foils as catalysts, while the conversion is carried out by a coupled reactor that
performs electrochemical reduction of carbon dioxide using ZnO as a catalyst and KHCO3 as an
electrolyte. The capture module is optimized such that, powered by a current density of 100 mA/cm2
,
from a mixture of the CO2–N2 gas stream, a pure and stable CO2 outlet flow of 4–5 mL/min is
obtained. The conversion module is able to convert the carbon dioxide into a mixture of gaseous
CO and H2
(syngas) with a selectivity for the carbon monoxide of 56%. This represents the first
all-electrochemical system for carbon dioxide capture and conversion
Italian Offshore Platform and Depleted Reservoir Conversion in the Energy Transition Perspective
New hypotheses for reusing platforms reaching their end-of-life have been investigated
in several works, discussing the potential conversions of these infrastructures from recreational
tourism to fish farming. In this perspective paper, we discuss the conversion options that could
be of interest in the context of the current energy transition, with reference to the off-shore Italian
scenario. The study was developed in support of the development of a national strategy aimed
at favoring a circular economy and the reuse of existing infrastructure for the implementation of
the energy transition. Thus, the investigated options include the onboard production of renewable
energy, hydrogen production from seawater through electrolyzers, CO2 capture and valorization,
and platform reuse for underground fluid storage in depleted reservoirs once produced through
platforms. Case histories are developed with reference to a typical, fictitious platform in the Adriatic
Sea, Italy, to provide an engineering-based approach to these different conversion options. The
coupling of the platform with the underground storage to set the optimal operational conditions is
managed through the forecast of the reservoir performance, with advanced numerical models able
to simulate the complexity of the phenomena occurring in the presence of coupled hydrodynamic,
geomechanical, geochemical, thermal, and biological processes. The results of our study are very
encouraging, because they reveal that no technical, environmental, or safety issues prevent the
conversion of offshore platforms into valuable infrastructure, contributing to achieving the energy
transition targets, as long as the selection of the conversion option to deploy is designed taking into
account the system specificity and including the depleted reservoir to which it is connected when
relevant. Socio-economic issues were not investigated, as they were out of the scope of the project
An Electrochemical Platform for the Carbon Dioxide Capture and Conversion to Syngas
We report on a simple electrochemical system able to capture gaseous carbon dioxide from a gas mixture and convert it into syngas. The capture/release module is implemented via regeneration of NaOH and acidification of NaHCO3 inside a four-chamber electrochemical flow cell employing Pt foils as catalysts, while the conversion is carried out by a coupled reactor that performs electrochemical reduction of carbon dioxide using ZnO as a catalyst and KHCO3 as an electrolyte. The capture module is optimized such that, powered by a current density of 100 mA/cm2, from a mixture of the CO2–N2 gas stream, a pure and stable CO2 outlet flow of 4–5 mL/min is obtained. The conversion module is able to convert the carbon dioxide into a mixture of gaseous CO and H2 (syngas) with a selectivity for the carbon monoxide of 56%. This represents the first all-electrochemical system for carbon dioxide capture and conversion
Solar-driven integrated carbon capture and utilization: Coupling CO2 electroreduction toward CO with capture or photovoltaic systems
Electrochemical processes have emerged as intriguing strategies for both CO2 capture and valorization, which are needed to combat global warming and climate change. Among other advantages over competing technologies, electrochemical systems can be powered by renewable sources, including solar energy.
This review aims at collecting and analyzing the main works proposed in the literature that study the coupling of electrochemical reactors for the conversion of CO2 into carbon monoxide with 1) electrochemical capture systems or 2) solar cells to power them. In addition to the critical analysis of these articles, a brief discussion of future research directions in this field is proposed