Special Issue "Catalytic, Photocatalytic and Electrocatalytic Processes for the Valorisation of CO2"

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Catalytic Materials".

Deadline for manuscript submissions: closed (31 July 2018).

Special Issue Editors

Guest Editor
Prof. Ilenia Rossetti Website E-Mail
Dip. Chimica, Università degli Studi di Milano, INSTM Unit Milano-Università and CNR-ISTM, via Golgi 19, 20133 Milano, Italy
Interests: process development; catalytic processes; heterogeneous catalysis ; photocatalysis; photoreactors design; transport phenomena; CO2 valorization; H2 production; process simulation; economic evaluation; renewable energy
Guest Editor
Prof. Gianguido Ramis Website E-Mail
Dipartimento di Ingegneria Chimica, Civile ed Ambientale, Università degli Studi di Genova and INSTM Unit Genova, Via all'Opera Pia 15A,16145 Genova, Italy
Interests: heterogeneous catalytic processes; characterization of surface active sites; SCR of NOx with NH3; catalytic oxidation; catalytic combustion of hydrocarbons and VOCs; C-H bonds activation; H2 production by steam reforming of bio-alcohols; CO2 photoreduction; photocatalytic H2 production

Special Issue Information

Dear Colleagues,

Increasing attention is paid to develop effective technologies for the sequestration of CO2 and its storage. In a virtuous view, they should be followed by processes that can lead to its valorisation as chemical, e.g. for the regeneration of fuels, but also for the production of intermediates. These are usually energy demanding and rather slow processes, requiring energy input and catalysts. Some examples are the innovative strategies for the photoconversion or electroreduction of carbon dioxide. This special issue collects original research papers, reviews and commentaries focused on the challenges for the valorisation and conversion of CO2. Submissions are welcome especially (but not exclusively) in the following areas:

- Catalytic processes for the conversion of CO2
- Photocatalytic processes for the conversion of CO2
- Electrocatalytic processes for the conversion of CO2
- Process design issues for the valorisation of CO2
- Economic and life cycle assessment in the valorisation of CO2
- Innovative processes and reactors for CO2 conversion

Assoc. Prof. Ilenia Rossetti
Prof. Gianguido Ramis
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Catalysts is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Valorisation of CO2
  • Catalytic reduction of CO2
  • CO2 photoreduction
  • CO2 electroreduction
  • CO2 as building block
  • Catalysts for CO2 conversion

Published Papers (8 papers)

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Editorial

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Open AccessEditorial
Catalytic, Photocatalytic, and Electrocatalytic Processes for the Valorization of CO2
Catalysts 2019, 9(9), 765; https://doi.org/10.3390/catal9090765 - 12 Sep 2019
Abstract
Worldwide yearly CO2 emissions reached 36 Gt in 2014, whereas they amounted to ca [...] Full article

Research

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Open AccessArticle
High Pressure Photoreduction of CO2: Effect of Catalyst Formulation, Hole Scavenger Addition and Operating Conditions
Catalysts 2018, 8(10), 430; https://doi.org/10.3390/catal8100430 - 30 Sep 2018
Cited by 5
Abstract
The photoreduction of CO2 is an intriguing process which allows the synthesis of fuels and chemicals. One of the limitations for CO2 photoreduction in the liquid phase is its low solubility in water. This point has been here addressed by designing [...] Read more.
The photoreduction of CO2 is an intriguing process which allows the synthesis of fuels and chemicals. One of the limitations for CO2 photoreduction in the liquid phase is its low solubility in water. This point has been here addressed by designing a fully innovative pressurized photoreactor, allowing operation up to 20 bar and applied to improve the productivity of this very challenging process. The photoreduction of CO2 in the liquid phase was performed using commercial TiO2 (Evonink P25), TiO2 obtained by flame spray pyrolysis (FSP) and gold doped P25 (0.2 wt% Au-P25) in the presence of Na2SO3 as hole scavenger (HS). The different reaction parameters (catalyst concentration, pH and amount of HS) have been addressed. The products in liquid phase were mainly formic acid and formaldehyde. Moreover, for longer reaction time and with total consumption of HS, gas phase products formed (H2 and CO) after accumulation of significant number of organic compounds in the liquid phase, due to their consecutive photoreforming. Enhanced CO2 solubility in water was achieved by adding a base (pH = 12–14). In basic environment, CO2 formed carbonates which further reduced to formaldehyde and formic acid and consequently formed CO/CO2 + H2 in the gas phase through photoreforming. The deposition of small Au nanoparticles (3–5 nm) (NPs) onto TiO2 was found to quantitatively influence the products distribution and increase the selectivity towards gas phase products. Significant energy storage in form of different products has been achieved with respect to literature results. Full article
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Open AccessArticle
Effect of In-Situ Dehydration on Activity and Stability of Cu–Ni–K2O/Diatomite as Catalyst for Direct Synthesis of Dimethyl Carbonate
Catalysts 2018, 8(9), 343; https://doi.org/10.3390/catal8090343 - 23 Aug 2018
Cited by 1
Abstract
An in-situ dehydrating system built in a continuous flow fixed-bed bubbling reactor for direct synthesis of dimethyl carbonate (DMC) was designed. 3A molecular sieve (MS) was selected as the ideal dehydrating agent and the water trapping efficiency was studied. The effect of dehydrating [...] Read more.
An in-situ dehydrating system built in a continuous flow fixed-bed bubbling reactor for direct synthesis of dimethyl carbonate (DMC) was designed. 3A molecular sieve (MS) was selected as the ideal dehydrating agent and the water trapping efficiency was studied. The effect of dehydrating agent/catalyst ratio, the dehydrating temperature and pressure, as well as the space velocity on the direct DMC synthesis catalyzed by K2O-promoted Cu–Ni was further investigated. These results demonstrated that 3A MS could effectively dehydrate the reaction system at the optimal conditions of 120 °C and 1.0 MPa with gas space velocity (GHSV) of 600 h−1, thereby greatly shifting the reaction equilibrium toward high DMC yield. Higher DMC yield of 13% was achieved compared with undehydrated reaction. Moreover, the catalyst can be highly stabilized by 3A MS dehydration with stable performs over 22 h. Full article
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Open AccessArticle
Evolution of Water Diffusion in a Sorption-Enhanced Methanation Catalyst
Catalysts 2018, 8(9), 341; https://doi.org/10.3390/catal8090341 - 21 Aug 2018
Cited by 3
Abstract
Sorption-enhanced methanation has consequent advantages compared to conventional methanation approaches; namely, the production of pure methane and enhanced kinetics thanks to the application of Le Châtelier’s principle. In this paper, we address the question of the long-term stability of a sorption-enhanced methanation catalyst-support [...] Read more.
Sorption-enhanced methanation has consequent advantages compared to conventional methanation approaches; namely, the production of pure methane and enhanced kinetics thanks to the application of Le Châtelier’s principle. In this paper, we address the question of the long-term stability of a sorption-enhanced methanation catalyst-support couple: Ni nanoparticles on zeolite 5A. Compared to most conventional methanation processes the operational conditions of sorption-enhanced methanation are relatively mild, which allow for stable catalyst activity on the long term. Indeed, we show here that neither coking nor thermal degradation come into play under such conditions. However, a degradation mechanism specific to the sorption catalysis was observed under cyclic methanation/drying periods. This severely affects water diffusion kinetics in the zeolite support, as shown here by a decrease of the water-diffusion coefficient during multiple cycling. Water diffusion is a central mechanism in the sorption-enhanced methanation process, since it is rate-limiting for both methanation and drying. Full article
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Open AccessArticle
Effect of Alkali-Doping on the Performance of Diatomite Supported Cu-Ni Bimetal Catalysts for Direct Synthesis of Dimethyl Carbonate
Catalysts 2018, 8(8), 302; https://doi.org/10.3390/catal8080302 - 27 Jul 2018
Cited by 2
Abstract
Alkali-adopted Cu-Ni/diatomite catalysts were designed and used for the direct synthesis of dimethyl carbonate (DMC) from carbon dioxide and methanol. Alkali additives were introduced into Cu-Ni/diatomite catalyst as a promoter because of its lower work function (Ni > Cu > Li > Na [...] Read more.
Alkali-adopted Cu-Ni/diatomite catalysts were designed and used for the direct synthesis of dimethyl carbonate (DMC) from carbon dioxide and methanol. Alkali additives were introduced into Cu-Ni/diatomite catalyst as a promoter because of its lower work function (Ni > Cu > Li > Na > K > Cs) and stronger electron-donating ability. A series of alkali-promoted Cu-Ni/diatomite catalysts were prepared by wetness impregnation method with different kind and different loading of alkali. The synthesized catalysts were fully characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), temperature-programmed reduction (TPR), and NH3/CO2-TPD. The experimental results demonstrated that alkali adoption can significantly promote the catalytic activity of Cu–Ni bimetallic catalysts. Under the catalytic reaction conditions of 120 °C and 1.0 MPa; the highest CH3OH conversion of 9.22% with DMC selectivity of 85.9% has been achieved when using 15%(2Cu-Ni) 2%Cs2O/diatomite catalyst (CuO + NiO = 15 wt. %, atomic ratio of Cu/Ni = 2/1, Cs2O = 2 wt. %). Full article
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Open AccessArticle
Metal-Carbon-CNF Composites Obtained by Catalytic Pyrolysis of Urban Plastic Residues as Electro-Catalysts for the Reduction of CO2
Catalysts 2018, 8(5), 198; https://doi.org/10.3390/catal8050198 - 09 May 2018
Cited by 2
Abstract
Metal–carbon–carbon nanofibers composites obtained by catalytic pyrolysis of urban plastic residues have been prepared using Fe, Co or Ni as pyrolitic catalysts. The composite materials have been fully characterized from a textural and chemical point of view. The proportion of carbon nanofibers and [...] Read more.
Metal–carbon–carbon nanofibers composites obtained by catalytic pyrolysis of urban plastic residues have been prepared using Fe, Co or Ni as pyrolitic catalysts. The composite materials have been fully characterized from a textural and chemical point of view. The proportion of carbon nanofibers and the final content of carbon phases depend on the used pyrolitic metal with Ni being the most active pyrolitic catalysts. The composites show the electro-catalyst activity in the CO2 reduction to hydrocarbons, favoring all the formation of C1 to C4 hydrocarbons. The tendency of this activity is in accordance with the apparent faradaic efficiencies and the linear sweep voltammetries. The cobalt-based composite shows high selectivity to C3 hydrocarbons within this group of compounds. Full article
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Open AccessArticle
Surface Oxidation of Supported Ni Particles and Its Impact on the Catalytic Performance during Dynamically Operated Methanation of CO2
Catalysts 2017, 7(9), 279; https://doi.org/10.3390/catal7090279 - 18 Sep 2017
Cited by 8
Abstract
The methanation of CO2 within the power-to-gas concept was investigated under fluctuating reaction conditions to gather detailed insight into the structural dynamics of the catalyst. A 10 wt % Ni/Al2O3 catalyst with uniform 3.7 nm metal particles and a [...] Read more.
The methanation of CO2 within the power-to-gas concept was investigated under fluctuating reaction conditions to gather detailed insight into the structural dynamics of the catalyst. A 10 wt % Ni/Al2O3 catalyst with uniform 3.7 nm metal particles and a dispersion of 21% suitable to investigate structural changes also in a surface-sensitive way was prepared and characterized in detail. Operando quick-scanning X-ray absorption spectroscopy (XAS/QEXAFS) studies were performed to analyze the influence of 30 s and 300 s H2 interruptions during the methanation of CO2 in the presence of O2 impurities (technical CO2). These conditions represent the fluctuating supply of H2 from renewable energies for the decentralized methanation. Short-term H2 interruptions led to oxidation of the most reactive low-coordinated metallic Ni sites, which could not be re-reduced fully during the subsequent methanation cycle and accordingly caused deactivation. Detailed evaluation of the extended X-ray absorption fine structure (EXAFS) spectra showed surface oxidation/reduction processes, whereas the core of the Ni particles remained reduced. The 300-s H2 interruptions resulted in bulk oxidation already after the first cycle and a more pronounced deactivation. These results clearly show the importance and opportunities of investigating the structural dynamics of catalysts to identify their mechanism, especially in power-to-chemicals processes using renewable H2. Full article
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Review

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Open AccessReview
Microwave, Ultrasound, and Mechanochemistry: Unconventional Tools that Are Used to Obtain “Smart” Catalysts for CO2 Hydrogenation
Catalysts 2018, 8(7), 262; https://doi.org/10.3390/catal8070262 - 28 Jun 2018
Cited by 5
Abstract
The most recent progress obtained through the precise use of enabling technologies, namely microwave, ultrasound, and mechanochemistry, described in the literature for obtaining improved performance catalysts (and photocatalysts) for CO2 hydrogenation, are reviewed. In particular, the main advantages (and drawbacks) found in [...] Read more.
The most recent progress obtained through the precise use of enabling technologies, namely microwave, ultrasound, and mechanochemistry, described in the literature for obtaining improved performance catalysts (and photocatalysts) for CO2 hydrogenation, are reviewed. In particular, the main advantages (and drawbacks) found in using the proposed methodologies will be discussed and compared by focusing on catalyst design and optimization of clean and efficient (green) synthetic processes. The role of microwaves as a possible activation tool used to improve the reaction yield will also be considered. Full article
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