Special Issue "Heterogeneous Catalysis for Valorization of Lignocellulosic Biomass"

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

Deadline for manuscript submissions: closed (31 May 2019).

Special Issue Editors

Dr. Cristina García-Sancho
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Guest Editor
Department Química Inorgánica, Cristalografía y Mineralogía, Facultad de Ciencias, Universidad de Málaga, Spain
Interests: catalysis with low valent transition metal complexes; heterogeneous catalysts; mesoporous materials; biomass valorization; biofuel and bioproducts
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Special Issue Information

Dear Colleagues,

With growing concerns about diminishing fossil fuels and the environmental damages that these resources involve, the search for renewable resources has attracted worldwide attention in recent years. In this sense, the use of biomass, as a renewable source of carbon for the production of biofuels and valuable chemicals, is a promising alternative as substitute for fossil resources. Among different types of biomass feedstocks, lignocellulosic biomass is abundant, inexpensive and with low impact on the food industry, being potentially more sustainable. Lignocellulosic biomass is mainly composed of polysaccharides (30–50% cellulose, 20–35% hemicellulose, 15–30% lignin), together with minor amounts of other materials (e.g., terpenes, oils, and inorganic minerals). In the concept of developing biorefineries, significant efforts have been and are still being devoted in the field of transformation of lignocellulose for the production of high-value products. Different value-added chemicals and high-quality fuel products can be generated from lignocellulosic biomass, such as organic acids (e.g., gluconic acid, formic acid, lactic acid, levulinic acid) and alcohols (sugar alcohols, ethylene glycol, and propylene glycol) from cellulose, furfural based compounds (e.g., 5-hydroxymethylfurfural and furfural) from cellulose and hemicellulose, and various aromatic chemicals from lignin. Moreover, some of these lignocellulose-derived chemicals can be considered as platform chemicals which can be converted to other value-added compounds through various reaction routes. In this context, the use of solid catalysts in order to improve the catalytic performances and reaction conditions is considered of great interest as alternative to homogeneous catalysis due to environmental and economic problems that this type of catalysis provokes.

Based on this situation, we would like to invite authors to publish papers and short reviews related to the use of heterogeneous catalysts in different reactions in order to obtain platform or fuel products from the valorization of lignocellulosic biomass.

Prof. Dr. Rafael Luque
Dr. Cristina García Sancho
Guest Editors

Manuscript Submission Information

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Keywords

  • heterogeneous catalysts
  • lignocellulosic biomass
  • green chemistry
  • platform molecules
  • biofuels

Published Papers (5 papers)

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Research

Open AccessArticle
Hydrodeoxygenation (HDO) of Aliphatic Oxygenates and Phenol over NiMo/MgAl2O4: Reactivity, Inhibition, and Catalyst Reactivation
Catalysts 2019, 9(6), 521; https://doi.org/10.3390/catal9060521 - 12 Jun 2019
Cited by 1
Abstract
This study provides new insights into sustainable fuel production by upgrading bio-derived oxygenates by catalytic hydrodeoxygenation (HDO). HDO of ethylene glycol (EG), cyclohexanol (Cyc), acetic acid (AcOH), and phenol (Phe) was investigated using a Ni-MoS2/MgAl2O4 catalyst. In addition, [...] Read more.
This study provides new insights into sustainable fuel production by upgrading bio-derived oxygenates by catalytic hydrodeoxygenation (HDO). HDO of ethylene glycol (EG), cyclohexanol (Cyc), acetic acid (AcOH), and phenol (Phe) was investigated using a Ni-MoS2/MgAl2O4 catalyst. In addition, HDO of a mixture of Phe/EG and Cyc/EG was studied as a first step towards the complex mixture in biomass pyrolysis vapor and bio-oil. Activity tests were performed in a fixed bed reactor at 380–450 °C, 27 bar H2, 550 vol ppm H2S, and up to 220 h on stream. Acetic acid plugged the reactor inlet by carbon deposition within 2 h on stream, underlining the challenges of upgrading highly reactive oxygenates. For ethylene glycol and cyclohexanol, steady state conversion was obtained in the temperature range of 380–415 °C. The HDO macro-kinetics were assessed in terms of consecutive dehydration and hydrogenation reactions. The results indicate that HDO of ethylene glycol and cyclohexanol involve different active sites. There was no significant influence from phenol or cyclohexanol on the rate of ethylene glycol HDO. However, a pronounced inhibiting effect from ethylene glycol on the HDO of cyclohexanol was observed. Catalyst deactivation by carbon deposition could be mitigated by oxidation and re-sulfidation. The results presented here demonstrate the need to address differences in oxygenate reactivity when upgrading vapors or oils derived from pyrolysis of biomass. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Valorization of Lignocellulosic Biomass)
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Open AccessFeature PaperArticle
Influence of the Incorporation of Basic or Amphoteric Oxides on the Performance of Cu-Based Catalysts Supported on Sepiolite in Furfural Hydrogenation
Catalysts 2019, 9(4), 315; https://doi.org/10.3390/catal9040315 - 31 Mar 2019
Cited by 1
Abstract
Cu-based catalysts supported on sepiolite have been tested in vapor-phase hydrogenation of furfural. The incorporation of basic or amphoteric metal oxides (magnesium oxide, zinc oxide, or cerium oxide) improves the catalytic behavior, reaching a maximum furfural conversion above 80% after 5 h of [...] Read more.
Cu-based catalysts supported on sepiolite have been tested in vapor-phase hydrogenation of furfural. The incorporation of basic or amphoteric metal oxides (magnesium oxide, zinc oxide, or cerium oxide) improves the catalytic behavior, reaching a maximum furfural conversion above 80% after 5 h of reaction at 210 °C. In all cases, the main product is furfuryl alcohol, obtaining 2-methylfuran in lower proportions. The incorporation of these metal oxide species ameliorates the dispersion of metallic Cu nanoparticles, increasing the number of available Cu0-sites, which enhances the catalytic performance. The presence of acid sites favors the hydrogenolysis of furfuryl alcohol towards 2-methylfuran, although it also causes an increase of carbon species on its surface, which is associated with the catalytic deactivation of the catalyst along the time-on-stream. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Valorization of Lignocellulosic Biomass)
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Open AccessArticle
Aqueous Dehydration, Hydrogenation, and Hydrodeoxygenation Reactions of Bio-Based Mucic Acid over Ni, NiMo, Pt, Rh, and Ru on Neutral or Acidic Catalyst Supports
Catalysts 2019, 9(3), 286; https://doi.org/10.3390/catal9030286 - 20 Mar 2019
Cited by 1
Abstract
Hydrotreatment of mucic acid (also known as galactaric acid, an glucaric acid enantiomer), one of the most promising bio-based platform chemicals, was systematically investigated in aqueous media over alumina, silica, or carbon-supported transition (nickel and nickel-molybdenum) or noble (platinum, ruthenium and rhodium) metals. [...] Read more.
Hydrotreatment of mucic acid (also known as galactaric acid, an glucaric acid enantiomer), one of the most promising bio-based platform chemicals, was systematically investigated in aqueous media over alumina, silica, or carbon-supported transition (nickel and nickel-molybdenum) or noble (platinum, ruthenium and rhodium) metals. Mucic acid was only converted into mucic-1,4-lactone under non-catalytic reaction conditions in N2 atmosphere, while the 5 MPa gaseous H2 addition triggers hydrogenation in the bulk phase, resulting in formation of galacturonic and galactonic acid. However, dehydroxylation, hydrogenation, decarbonylation, decarboxylation, and cyclization occurred during catalytic hydrotreatment, forming various partially and completely deoxygenated products with a chain length of 3–6 C atoms. Characterization results of tested catalysts were correlated with their activity and selectivity. Insufficient pore diameter of microporous supports completely hindered the mass transfer of reactants to the active sites, resulting in negligible conversion of mucic acid. A comprehensive reaction pathway network was proposed and several industrially interesting compounds were formed, including levulinic acid, furoic acid, and adipic acid. However, selectivity towards adipic acid, a bio-based nylon 6,6 precursor, was low (up to 5 mol%) in aqueous media and elevated temperatures. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Valorization of Lignocellulosic Biomass)
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Open AccessArticle
Solvothermal Conversion of Lignosulfonate Assisted by Ni Catalyst: Investigation of the Role of Ethanol and Ethylene Glycol as Solvents
Catalysts 2018, 8(11), 502; https://doi.org/10.3390/catal8110502 - 27 Oct 2018
Abstract
In this study, reductive solvolysis of lignosulfonate using Ni-based catalysts in ethylene glycol (EG) and ethanol (EtOH) at 250 °C was investigated. The liquefied fractions, regarded as oil, were carefully analyzed using size-exclusion chromatography (SEC) and gas chromatography–mass spectrometry with flame ionization detection [...] Read more.
In this study, reductive solvolysis of lignosulfonate using Ni-based catalysts in ethylene glycol (EG) and ethanol (EtOH) at 250 °C was investigated. The liquefied fractions, regarded as oil, were carefully analyzed using size-exclusion chromatography (SEC) and gas chromatography–mass spectrometry with flame ionization detection (GC-MS-FID). The oil yields from catalytic conversion in EtOH and EG were similar, being 31 and 32 wt.%, respectively. The oil fractions from depolymerization in EtOH had lower molecular weight compared to the oil products in EG, indicating a higher degree of degradation of liquefied products in EtOH. On the other hand, EG showed superior activity in inhibiting condensation reactions; 16 and 46 wt.% tetrahydrofuran (THF) soluble and THF insoluble solid fractions were obtained from conversion in EtOH, while those numbers in EG were 45 and 23 wt.%, respectively. The Ni-based catalyst was introduced to provide active sites for hydrogenation of lignosulfonate fragments released into the solvent. The presence of NiS in the spent catalyst, formed from reaction between Ni and sulfur in the lignosulfonate, was confirmed. The sulfur content in the oil obtained in EtOH was 0.38 wt.%, which in comparison to lignosulfonate with 3.1 wt.% sulfur, indicated a high level of desulfurization. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Valorization of Lignocellulosic Biomass)
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Open AccessArticle
Catalytic Hydrogenation, Hydrodeoxygenation, and Hydrocracking Processes of a Lignin Monomer Model Compound Eugenol over Magnetic Ru/C–Fe2O3 and Mechanistic Reaction Microkinetics
Catalysts 2018, 8(10), 425; https://doi.org/10.3390/catal8100425 - 28 Sep 2018
Cited by 5
Abstract
Conversion of waste lignocellulosic (LC) biomass, a widely-available low-cost feedstock, into value-added biobased chemicals (and biofuels) has been gaining much attention recently. Therefore, the present lignin valorisation study was aimed at developing magnetically-separable highly-active catalysts for hydrodeoxygenation (HDO), also proposing surface chemical kinetics. [...] Read more.
Conversion of waste lignocellulosic (LC) biomass, a widely-available low-cost feedstock, into value-added biobased chemicals (and biofuels) has been gaining much attention recently. Therefore, the present lignin valorisation study was aimed at developing magnetically-separable highly-active catalysts for hydrodeoxygenation (HDO), also proposing surface chemical kinetics. Five carbonaceous substrate-deposited Ru were synthesised and tested for the HDO of monomer moiety eugenol. Their annealing temperatures differed, specifically between 300 and 750 °C, while one was not subjected to calcination. Experiments revealed the substantial influence of annealing temperature on the product distribution. Namely, fresh nonannealed nanocomposites were not active for hydrogenolysis. By further pretreatment increase, hydrogenation and, exclusively, the deoxygenation of saturated cyclic species, were enhanced, these being more promoted considering rates and yields than commercial carbon-supported ruthenium. Over 80 mol% of 4-propyl-cylohexanol and propyl-cyclohexane could be formed over the samples, treated at 500 and 600 °C, for 100 and 125 min, respectively, under 275 °C and 5 MPa of reactor hydrogen pressure. Interestingly, a notable 4-propyl-phenol amount was produced upon 750 °C pretreating. The intrinsic microkinetic model, developed previously, was applied to determine relevant turnover parameters. Calculated modelling results indicated a 47- and 10-fold greater demethoxylation and dehydroxylation mechanism ability upon the reheatingpreheating at 600 °C in comparison to industrial (heterogeneous) Ru/C. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Valorization of Lignocellulosic Biomass)
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