Special Issue "Solid Catalysts for the Upgrading of Renewable Sources"

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

Deadline for manuscript submissions: closed (31 July 2018)

Special Issue Editors

Guest Editor
Dr. Nicoletta Ravasio

CNR Istituto di Scienze e Tecnologie Molecolari, Via Golgi 19, 20133 Milan, Italy
Website | E-Mail
Interests: catalysis; food waste valorization; biorefinery; oleochemicals
Guest Editor
Dr. Federica Zaccheria

CNR, Istituto di Scienze e Tecnologie Molecolari, Via Golgi, 19 20133 Milano, Italy
Website | E-Mail
Interests: heterogeneous catalysis; biorefinery; renewables

Special Issue Information

Dear Colleagues,

The use of solid catalysts for the upgrading of renewable sources gives the opportunity to combine the two main cores of green chemistry, that is, on the one hand, the setting up of sustainable processes and, on the other, the use of biomass-derived materials. Solid catalysts have taken on a leading role in traditional petrochemical processes and could, therefore, also represent a key tool in new biorefinery driven technologies. 

This Special Issue will cover topics related to the preparation and use of heterogeneous catalytic systems for the transformation of renewable sources, as well as of materials deriving from agro-industrial wastes and by-products. Valorization of rest raw materials represents a crucial challenge in the roadmap to a circular economy.

At the same time, the ever-increasing importance of bioproducts, due to the acceptance and request of consumers, makes the upgrading of biomass into chemicals and materials, not only an environmental issue, but also an economical advantage.

In this Special Issue we invite the main groups involved in heterogeneous catalysis applied to renewable materials to contribute original papers, mini reviews or commentaries in order to give an overview of the state-of-the-art in this field and an interpretation of the open challenges and opportunities. The main focus will be devoted to the transformation and upgrading of:

  1. Lignocellulosic materials
  2. Vegetable oils
  3. Terpenes
  4. Agro-industrial wastes and by-products

Dr. Nicoletta Ravasio
Dr. Federica Zaccheria
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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 1300 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

  • Heterogeneous catalysis
  • Bioproducts
  • Biomass
  • Lignocellulosic raw materials
  • Vegetable oils
  • Terpenes
  • Solid Lewis acids
  • Selective hydrogenation
  • Bifunctional catalysis

Published Papers (5 papers)

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Research

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Open AccessArticle Ru-(Mn-M)OX Solid Base Catalysts for the Upgrading of Xylitol to Glycols in Water
Catalysts 2018, 8(8), 331; https://doi.org/10.3390/catal8080331
Received: 26 July 2018 / Revised: 10 August 2018 / Accepted: 11 August 2018 / Published: 14 August 2018
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Abstract
A series of Ru-(Mn-M)OX catalysts (M: Al, Ti, Zr, Zn) prepared by co-precipitation were investigated in the hydrogenolysis of xylitol in water to ethylene glycol, propylene glycol and glycerol at 200 °C and 60 bar of H2. The catalyst promoted
[...] Read more.
A series of Ru-(Mn-M)OX catalysts (M: Al, Ti, Zr, Zn) prepared by co-precipitation were investigated in the hydrogenolysis of xylitol in water to ethylene glycol, propylene glycol and glycerol at 200 °C and 60 bar of H2. The catalyst promoted with Al, Ru-(Mn-Al)OX, showed superior activity (57 h−1) and a high global selectivity to glycols and glycerol of 58% at 80% xylitol conversion. In comparison, the catalyst prepared by loading Ru on (Mn-Al)OX, Ru/(Mn-Al)OX was more active (111 h−1) but less selective (37%) than Ru-(Mn-Al)OX. Characterization of these catalysts by XRD, BET, CO2-TPD, NH3-TPD and TEM showed that Ru/(Mn-Al)OX contained highly dispersed and uniformly distributed Ru particles and fewer basic sites, which favored decarbonylation, epimerization and cascade decarbonylation reactions instead of retro-aldol reactions producing glycols. The hydrothermal stability of Ru-(Mn-Al)OX was improved by decreasing the xylitol/catalyst ratio, which decreased the formation of carboxylic acids and enabled recycling of the catalyst, with a very low deactivation. Full article
(This article belongs to the Special Issue Solid Catalysts for the Upgrading of Renewable Sources)
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Open AccessArticle Acid–Base Bifunctional Hf Nanohybrids Enable High Selectivity in the Catalytic Conversion of Ethyl Levulinate to γ-Valerolactone
Catalysts 2018, 8(7), 264; https://doi.org/10.3390/catal8070264
Received: 26 May 2018 / Revised: 18 June 2018 / Accepted: 26 June 2018 / Published: 29 June 2018
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Abstract
The catalytic upgrading of bio-based platform molecules is a promising approach for biomass valorization. However, most solid catalysts are not thermally or chemically stable, and are difficult to prepare. In this study, a stable organic phosphonate–hafnium solid catalyst (PPOA–Hf) was synthesized, and acid–base
[...] Read more.
The catalytic upgrading of bio-based platform molecules is a promising approach for biomass valorization. However, most solid catalysts are not thermally or chemically stable, and are difficult to prepare. In this study, a stable organic phosphonate–hafnium solid catalyst (PPOA–Hf) was synthesized, and acid–base bifunctional sites were found to play a cooperative role in the cascade transfer hydrogenation and cyclization of ethyl levulinate (EL) to γ-valerolactone (GVL). Under relatively mild reaction conditions of 160 °C for 6 h, EL was completely converted to GVL with a good yield of 85%. The apparent activation energy was calculated to be 53 kJ/mol, which was lower than other solid catalysts for the same reaction. In addition, the PPOA-Hf solid catalyst did not significantly decrease its activity after five recycles, and no evident leaching of Hf was observed, indicating its high stability and potential practical application. Full article
(This article belongs to the Special Issue Solid Catalysts for the Upgrading of Renewable Sources)
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Review

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Open AccessReview Metal–Organic Frameworks-Based Catalysts for Biomass Processing
Catalysts 2018, 8(9), 368; https://doi.org/10.3390/catal8090368
Received: 5 August 2018 / Revised: 20 August 2018 / Accepted: 21 August 2018 / Published: 31 August 2018
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Abstract
Currently, metal–organic frame works (MOFs) as novel hybrid nanoporous materials are a top research interest, including endeavors in heterogeneous catalysis. MOF materials are promising heterogeneous catalytic systems due to their unique characteristics, such as a highly ordered structure, a record high surface area
[...] Read more.
Currently, metal–organic frame works (MOFs) as novel hybrid nanoporous materials are a top research interest, including endeavors in heterogeneous catalysis. MOF materials are promising heterogeneous catalytic systems due to their unique characteristics, such as a highly ordered structure, a record high surface area and a compositional diversity, which can be precisely tailored. Very recently, these metal-organic matrices have been proven as promising catalysts for biomass conversion into value-added products. The relevant publications show that the structure of MOFs can contribute essentially to the advanced catalytic performance in processes of biomass refining. This review aims at the consideration of the different ways for the rational design of MOF catalysts for biomass processing. The particular characteristics and peculiarities of the behavior of different MOF based catalytic systems including hybrid nanomaterials and composites will be also discussed by illustrating their outstanding performance with appropriate examples relevant to biomass catalytic processing. Full article
(This article belongs to the Special Issue Solid Catalysts for the Upgrading of Renewable Sources)
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Open AccessReview Valorization of Biomass Derived Terpene Compounds by Catalytic Amination
Catalysts 2018, 8(9), 365; https://doi.org/10.3390/catal8090365
Received: 30 July 2018 / Revised: 22 August 2018 / Accepted: 26 August 2018 / Published: 29 August 2018
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Abstract
This review fills an apparent gap existing in the literature by providing an overview of the readily available terpenes and existing catalytic protocols for preparation of terpene-derived amines. To address the role of solid catalysts in amination of terpenes the same reactions with
[...] Read more.
This review fills an apparent gap existing in the literature by providing an overview of the readily available terpenes and existing catalytic protocols for preparation of terpene-derived amines. To address the role of solid catalysts in amination of terpenes the same reactions with homogeneous counterparts are also discussed. Such catalysts can be considered as a benchmark, which solid catalysts should match. Although catalytic systems based on transition metal complexes have been developed for synthesis of amines to a larger extent, there is an apparent need to reduce the production costs. Subsequently, homogenous systems based on cheaper metals operating by nucleophilic substitution (e.g., Ni, Co, Cu, Fe) with a possibility of easy recycling, as well as metal nanoparticles (e.g., Pd, Au) supported on amphoteric oxides should be developed. These catalysts will allow synthesis of amine derivatives of terpenes which have a broad range of applications as specialty chemicals (e.g., pesticides, surfactants, etc.) and pharmaceuticals. The review will be useful in selection and design of appropriate solid materials with tailored properties as efficient catalysts for amination of terpenes. Full article
(This article belongs to the Special Issue Solid Catalysts for the Upgrading of Renewable Sources)
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Open AccessReview Preparation and Application of Biochar-Based Catalysts for Biofuel Production
Catalysts 2018, 8(9), 346; https://doi.org/10.3390/catal8090346
Received: 19 July 2018 / Revised: 4 August 2018 / Accepted: 17 August 2018 / Published: 24 August 2018
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Abstract
Firstly, this paper reviews two main methods for biochar synthesis, namely conventional pyrolysis and hydrothermal carbonization (HTC). The related processes are described, and the influences of biomass nature and reaction conditions, especially temperature, are discussed. Compared to pyrolysis, HTC has advantages for processing
[...] Read more.
Firstly, this paper reviews two main methods for biochar synthesis, namely conventional pyrolysis and hydrothermal carbonization (HTC). The related processes are described, and the influences of biomass nature and reaction conditions, especially temperature, are discussed. Compared to pyrolysis, HTC has advantages for processing high-moisture biomass and producing spherical biochar particles. Secondly, typical features of biochar in comparison with other carbonaceous materials are summarized. They refer to the presence of inorganics, surface functional groups, and local crystalline structures made up of highly conjugated aromatic sheets. Thirdly, various strategies for biochar modification are illustrated. They include activation, surface functionalization, in situ heteroatom doping, and the formation of composites with other materials. An appropriate modification is necessary for biochar used as a catalyst. Fourthly, the applications of biochar-based catalysts in three important processes of biofuel production are reviewed. Sulfonated biochar shows good catalytic performance for biomass hydrolysis and biodiesel production. Biodiesel production can also be catalyzed by biochar-derived or -supported solid-alkali catalysts. Biochar alone and biochar-supported metals are potential catalysts for tar reduction during or after biomass gasification. Lastly, the merits of biochar-based catalysts are summarized. Biochar-based catalysts have great developmental prospects. Future work needs to focus on the study of mechanism and process design. Full article
(This article belongs to the Special Issue Solid Catalysts for the Upgrading of Renewable Sources)
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