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Special Issue "Heterogeneous Catalysts for the Valorization of Biomass Derived Compounds"

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Green Chemistry".

Deadline for manuscript submissions: 31 January 2024 | Viewed by 4460

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Special Issue Editor

Dr. Margarida M. Antunes

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Guest Editor

Department of Chemistry, CICECO–Aveiro Institute of Materials, University of Aveiro, Aveiro, Portugal
Interests: vegetable biomass; heterogeneous catalysis; multifunctional catalysts; hydrolysis; dehydration; catalytic transfer hydrogenation; one-pot reactions

Special Issue Information

Dear Colleagues,

The anthropogenic emissions caused by the use of fossil fuels prompt demand for sustainable renewable alternatives. Biomass plays an important role in mitigating climate change, as it is the most abundant renewable source of organic carbon available on Earth. It can be found in terrestrial agriculture, such as in forestry, food and other solid residues, or aquatic biomass, such as in the form of algae residues. The valorization of these residues is possible due to the components present therein, such as cellulose, hemicelluloses, lignin and starch. These components can be converted to important biofuels and chemicals, such as organic acids, furanic aldehydes, furanic ethers, levulinates, aromatics and amino acids with applications in several sectors of the chemical industry. Homogeneous catalysts can be very efficient in several conversion processes, but they present several drawbacks such as difficult recovery and separation from the target products, with increased costs. The use of multifunctional heterogenous catalysts is important to enhance the productivity of the processes and allow multiple steps to be carried out in only one reactor. Hence, the development of suitable heterogeneous catalysts for biomass valorization is crucial. This issue covers all aspects of heterogeneous catalysis applied to the valorization of vegetable biomass and derived compounds for producing useful chemicals, biofuels or fuel additives.

Dr. Margarida M. Antunes
Guest Editor

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Keywords

waste and biomass valorization
fuels
bioproducts
heterogeneous catalysts
hydrogenation
oxidation
condensation

Published Papers (5 papers)

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Research

Open AccessArticle

Conversion of Similar Xenochemicals to Dissimilar Products: Exploiting Competing Reactions in Whole-Cell Catalysis

Francesca Sannelli

Nikoline Corell Sindahl

Stefan S. Warthegau

Pernille Rose Jensen

and

Sebastian Meier

Molecules 2023, 28(13), 5157; https://doi.org/10.3390/molecules28135157 - 01 Jul 2023

Viewed by 555

Abstract

Many enzymes have latent activities that can be used in the conversion of non-natural reactants for novel organic conversions. A classic example is the conversion of benzaldehyde to a phenylacetyl carbinol, a precursor for ephedrine manufacture. It is often tacitly assumed that purified enzymes are more promising catalysts than whole cells, despite the lower cost and easier maintenance of the latter. Competing substrates inside the cell have been known to elicit currently hard-to-predict selectivities that are not easily measured inside the living cell. We employ NMR spectroscopic assays to rationally combine isomers for selective reactions in commercial S. cerevisiae. This approach uses internal competition between alternative pathways of aldehyde clearance in yeast, leading to altered selectivities compared to catalysis with the purified enzyme. In this manner, 4-fluorobenzyl alcohol and 2-fluorophenylacetyl carbinol can be formed with selectivities in the order of 90%. Modification of the cellular redox state can be used to tune product composition further. Hyperpolarized NMR shows that the cellular reaction and pathway usage are affected by the xenochemical. Overall, we find that the rational construction of ternary or more complex substrate mixtures can be used for in-cell NMR spectroscopy to optimize the upgrading of similar xenochemicals to dissimilar products with cheap whole-cell catalysts. Full article

(This article belongs to the Special Issue Heterogeneous Catalysts for the Valorization of Biomass Derived Compounds)

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Open AccessArticle

Heterogenization of Heteropolyacid with Metal-Based Alumina Supports for the Guaiacol Gas-Phase Hydrodeoxygenation

Rita F. Nunes

Daniel Costa

Ana M. Ferraria

Ana M. Botelho do Rego

Filipa Ribeiro

Ângela Martins

and

Auguste Fernandes

Molecules 2023, 28(5), 2245; https://doi.org/10.3390/molecules28052245 - 28 Feb 2023

Cited by 1 | Viewed by 757

Abstract

Because of the global necessity to decrease CO₂ emissions, biomass-based fuels have become an interesting option to explore; although, bio-oils need to be upgraded, for example, by catalytic hydrodeoxygenation (HDO), to reduce oxygen content. This reaction generally requires bifunctional catalysts with both metal and acid sites. For that purpose, Pt-Al₂O₃ and Ni-Al₂O₃ catalysts containing heteropolyacids (HPA) were prepared. HPAs were added by two different methods: the impregnation of a H₃PW₁₂O₄₀ solution onto the support and a physical mixture of the support with Cs_2.5H_0.5PW₁₂O₄₀. The catalysts were characterized by powder X-ray diffraction, Infrared, UV-Vis, Raman, X-ray photoelectron spectroscopy and NH₃-TPD experiments. The presence of H₃PW₁₂O₄₀ was confirmed by Raman, UV-Vis and X-ray photoelectron spectroscopy, while the presence of Cs_2.5H_0.5PW₁₂O₄₀ was confirmed by all of the techniques. However, HPW was shown to strongly interact with the supports, especially in the case of Pt-Al₂O₃. These catalysts were tested in the HDO of guaiacol, at 300 °C, under H₂ and at atmospheric pressure. Ni-based catalysts led to higher conversion and selectivity to deoxygenated compound values, such as benzene. This is attributed to both a higher metal and acidic contents of these catalysts. Among all tested catalysts, HPW/Ni-Al₂O₃ was shown to be the most promising, although it suffered a more severe deactivation with time-on-stream. Full article

(This article belongs to the Special Issue Heterogeneous Catalysts for the Valorization of Biomass Derived Compounds)

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Open AccessArticle

Hydration of Camphene over PW-SBA-15-SO₃H

José Castanheiro

Molecules 2023, 28(1), 6; https://doi.org/10.3390/molecules28010006 - 20 Dec 2022

Viewed by 714

Abstract

The hydration of camphene was carried out over SBA-15 with sulfonic acid groups and tungstophosphoric acid at 50 °C. The main product of camphene hydration was isoborneol, with camphene hydrate and borneol as byproducts. The catalytic activity increased with the amount of tungstophosforic acid (PW) immobilized on the silica support until a maximum, which was obtained with the PW4-SBA-15-SO₃H material (16.4 wt.%). When the amount of PW immobilized on SBA-15 increased (PW5-SBA-15-SO₃H, 21.2 wt.%), the catalytic activity decreased. The catalytic activity of PW4-SBA-15-SO₃H increased with the water content of the solvent, until a maximum was reached with 50% water. With higher water concentrations, a decrease in the catalytic activity was observed. The selectivity to isoborneol was 90% at 99% camphene conversion in the presence of the PW4-SBA-15-SO₃H catalyst. The catalytic stability of the PW4-SBA-15-SO₃H material during camphene hydration was studied by performing consecutive batch runs with the same catalyst sample. After the third run, a trend towards stabilized catalytic activity was observed. A kinetic model is also proposed. Full article

(This article belongs to the Special Issue Heterogeneous Catalysts for the Valorization of Biomass Derived Compounds)

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Open AccessArticle

Sustainable Ketalization of Glycerol with Ethyl Levulinate Catalyzed by the Iron(III)-Based Metal-Organic Framework MIL-88A

Massimo Melchiorre

Domenico Lentini

Maria Elena Cucciolito

and

Molecules 2022, 27(21), 7229; https://doi.org/10.3390/molecules27217229 - 25 Oct 2022

Cited by 4 | Viewed by 1092

Abstract

The catalytic properties of a simple iron-containing MOF based on fumaric acid, MIL-88A, were investigated in the ketalization of ethyl levulinate with glycerol. The corresponding product is a component of current interest as a renewable building block for many uses. Under the following conditions (solventless, 120 °C, stoichiometric ratio, 1% cat.), the reaction proceeds with good yields (85%), and the catalyst can be recovered and recycled without loss of activity, despite some changes in the crystalline lattice and morphology. Moreover, the residual iron content in the product is in the order of units of ppm (≤2), which demonstrates the robustness of the MOF under the reaction conditions. Full article

(This article belongs to the Special Issue Heterogeneous Catalysts for the Valorization of Biomass Derived Compounds)

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Open AccessArticle

Easy and Fast Production of Solketal from Glycerol Acetalization via Heteropolyacids

Diana Julião

Fatima Mirante

and

Salete S. Balula

Molecules 2022, 27(19), 6573; https://doi.org/10.3390/molecules27196573 - 04 Oct 2022

Cited by 2 | Viewed by 812

Abstract

This work presents an effective and fast procedure to valorize the main waste produced from the biodiesel industry, i.e., the glycerol. The acetalization of glycerol with acetone represents an effective strategy to produce the valuable solketal, a fuel additive component. In this work, the catalytic efficiency of different commercial heteropolyacids (HPAas) was compared under a solvent-free system. The HPAs used were H₃[PW₁₂O₄₀] (PW₁₂), H₃[PMo₁₂O₄₀] (PMo₁₂) and H₄[SiW₁₂O₄₀] (SiW₁₂). The influence of reactional parameters such as reactants stoichiometry, catalyst concentration and reaction temperature were investigated in order to optimize experimental conditions to increase cost-efficiency and sustainability. HPAs demonstrated to be highly efficient for this type of reaction, presenting a high and fast glycerol conversion, with high selectivity to solketal under sustainable conditions (solvent-free system and room temperature medium). The activity of HPAs using 3% to glycerol weight and a glycerol/acetone ratio of 1:15 followed the order: PW₁₂ (99.2%) > PMo₁₂ (91.4%) > SiW₁₂ (90.7%) as a result of the strong acidic sites after 5 min. In fact, only 5 min of reaction were needed to achieve 97% of solketal product in the presence of the PW₁₂ as a catalyst. This last system presents an effective, selective and sustainable catalytic system to valorize glycerol. Full article

(This article belongs to the Special Issue Heterogeneous Catalysts for the Valorization of Biomass Derived Compounds)

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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Autocatalytic oxidation of municipal biowaste
Authors: Enzo Montoneri (a), Mattero Francavilla (b), Elio Padoan (c)
Affiliation: a) Università di Catania (IT), (b) Università di Foggia (IT), (c) Università di Torino (IT).
Abstract: Autocatalytic oxidation of municipal biowaste is performed in the presence a photosensitizer (PHTS) as reaction product, using water as solvent/reagent, solar light as energy source, and hydrogen peroxide and ozone as alternative auxiliary oxidants. The process allows obtaining biopolymers (BPM) for the production of bioplastics, biosurfactants (BPS) and other building blocks (BBB) molecules for the chemical industry. The expected environmental and economic benefits of the above process and products are discussed in comparison with other known technologies for the valorization of biomass derived compounds.

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Special Issue "Heterogeneous Catalysts for the Valorization of Biomass Derived Compounds"

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