Special Issue "Biomass Derived Heterogeneous and Homogeneous Catalysts"

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

Deadline for manuscript submissions: closed (30 June 2020).

Special Issue Editors

Prof. Dr. José María Encinar Martín
Website
Guest Editor
Department of Chemical Engineering and Physical Chemistry, University of Extremadura, Avda. De Elvas s/n, 06006 Badajoz, Spain
Interests: biomass; biodiesel; biolubricants; oxidative stability; fatty acid methyl esters; catalyst; pyrolysis; gasification
Special Issues and Collections in MDPI journals
Dr. Sergio Nogales Delgado
Website
Guest Editor
Department of Chemical Engineering and Physical Chemistry, University of Extremadura, Avda. De Elvas s/n, 06006 Badajoz, Spain
Interests: biomass; biodiesel; biolubricants; oxidative stability; fatty acid methyl esters; catalyst; viscosity
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Renewable energy sources will play a decisive role in the future development of mankind. The increase in energy demand and the need of replacing fossil fuels make the development of new renewable raw materials mandatory, in order to generate sustainable fuels and chemical products.

For this reason, the production of biodiesel, bioethanol, biolubricants and the development of biorefineries are promising research fields, among other alternatives. Some of these products are currently a reality, but the large-scale economic development is still uncertain due to the competition with fossil fuels. A significant and essential issue to overcome that challenge is the research and use of new catalysts to carry out the synthesis processes of bioproducts more efficiently.

For this Special Issue, we invite papers dealing with the use of homogeneous and heterogeneous catalysts for the development of processes such as biodiesel, biolubricant or biofuel production.

More specifically, topics of interest for the Special Issue include (but are not limited to):

  • Biomass
  • Biofuels
  • Biorefinery
  • Bioproducts
  • Biochemicals
  • Biorenewables
  • Bioenergy–Biofuels by-products
  • Biodiesel
  • Biolubricants
  • Bioethanol
  • Biomethane

Dr. José María Encinar Martín
Dr. Sergio Nogales Delgado
Guest Editors

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 2000 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

  • Bioproducts
  • Biodiesel
  • Bioethanol
  • Bioenergy
  • Biolubricants
  • Homogeneous and Heterogeneous Catalysts

Published Papers (12 papers)

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Editorial

Jump to: Research, Review

Open AccessEditorial
Editorial Catalysts: Special Issue on “Biomass Derived Heterogeneous and Homogeneous Catalysts”
Catalysts 2020, 10(12), 1433; https://doi.org/10.3390/catal10121433 - 08 Dec 2020
Abstract
The replacement of petrol products for environmentally-friendly ones is a reality today, as many governments and international organizations are promoting the implementation of renewable energy sources and natural feedstocks in industrial activity [...] Full article
(This article belongs to the Special Issue Biomass Derived Heterogeneous and Homogeneous Catalysts)
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Research

Jump to: Editorial, Review

Open AccessArticle
Response Surface Methodology for the Optimization of Keratinase Production in Culture Medium Containing Feathers by Bacillus sp. UPM-AAG1
Catalysts 2020, 10(8), 848; https://doi.org/10.3390/catal10080848 - 29 Jul 2020
Cited by 1
Abstract
Keratinase is a type of proteolytic enzyme with broad application in industry. The main objective of this work is the optimization of keratinase production from Bacillus sp. strain UPM-AAG1 using Plackett-Burman (PB) and central composite design (CCD) for parameters, such as pH, temperature, [...] Read more.
Keratinase is a type of proteolytic enzyme with broad application in industry. The main objective of this work is the optimization of keratinase production from Bacillus sp. strain UPM-AAG1 using Plackett-Burman (PB) and central composite design (CCD) for parameters, such as pH, temperature, feather concentration, and inoculum size. The optimum points for temperature, pH, and inoculum and feather concentrations were 31.66 °C, 6.87, 5.01 (w/v), and 4.53 (w/v), respectively, with an optimum keratinase activity of 60.55 U/mL. The keratinase activity was further numerically optimized for commercial application. The best numerical solution recommended a pH of 5.84, temperature of 25 °C, inoculums’ size of 5.0 (v/v), feather concentration of 4.97 (w/v). Optimization resulted an activity of 56.218 U/mL with the desirability value of 0.968. Amino acid analysis profile revealed the presence of essential and non-essential amino acids. These properties make Bacillus sp. UPM-AAG1 a potential bacterium to be used locally for the production of keratinase from feather waste. Full article
(This article belongs to the Special Issue Biomass Derived Heterogeneous and Homogeneous Catalysts)
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Open AccessArticle
Study of Curing Characteristics of Cellulose Nanofiber-Filled Epoxy Nanocomposites
Catalysts 2020, 10(8), 831; https://doi.org/10.3390/catal10080831 - 24 Jul 2020
Cited by 2
Abstract
In recent years, much attention was focused on developing green materials and fillers for polymer composites. This work is about the development of such green nanofiller for reinforcement in epoxy polymer matrix. A cellulose nanofiber (CNF)-filled epoxy polymer nanocomposites was prepared in this [...] Read more.
In recent years, much attention was focused on developing green materials and fillers for polymer composites. This work is about the development of such green nanofiller for reinforcement in epoxy polymer matrix. A cellulose nanofiber (CNF)-filled epoxy polymer nanocomposites was prepared in this work. The effect of CNF on curing, thermal, mechanical, and barrier properties of epoxy polymer is evaluated in this study. CNF were extracted from banana fiber using acid hydrolysis method and then filled in epoxy polymer at various concentration (0–5 wt.%) to form CNF-filled epoxy nanocomposites. The structure and morphology of the CNF-filled epoxy nanocomposites were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. Curing studies shows CNF particles acts as a catalytic curing agent with increased cross-link density. This catalytic effect of CNF particles has positively affected tensile, thermal (thermogravimetry analysis and dynamic mechanical analysis) and water barrier properties. Water uptake test of nanocomposites was studied to understand the barrier properties. Overall result also shows that the CNF can be a potential green nanofiller for thermoset epoxy polymer with promising applications ahead. Full article
(This article belongs to the Special Issue Biomass Derived Heterogeneous and Homogeneous Catalysts)
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Open AccessArticle
Conversion of Xylose to Furfural over Lignin-Based Activated Carbon-Supported Iron Catalysts
Catalysts 2020, 10(8), 821; https://doi.org/10.3390/catal10080821 - 22 Jul 2020
Cited by 1
Abstract
In this study, conversion of xylose to furfural was studied using lignin-based activated carbon-supported iron catalysts. First, three activated carbon supports were prepared from hydrolysis lignin with different activation methods. The supports were modified with different metal precursors and metal concentrations into five [...] Read more.
In this study, conversion of xylose to furfural was studied using lignin-based activated carbon-supported iron catalysts. First, three activated carbon supports were prepared from hydrolysis lignin with different activation methods. The supports were modified with different metal precursors and metal concentrations into five iron catalysts. The prepared catalysts were studied in furfural production from xylose using different reaction temperatures and times. The best results were achieved with a 4 wt% iron-containing catalyst, 5Fe-ACs, which produced a 57% furfural yield, 92% xylose conversion and 65% reaction selectivity at 170 °C in 3 h. The amount of Fe in 5Fe-ACs was only 3.6 µmol and using this amount of homogeneous FeCl3 as a catalyst, reduced the furfural yield, xylose conversion and selectivity. Good catalytic activity of 5Fe-ACs could be associated with iron oxide and hydroxyl groups on the catalyst surface. Based on the recycling experiments, the prepared catalyst needs some improvements to increase its stability but it is a feasible alternative to homogeneous FeCl3. Full article
(This article belongs to the Special Issue Biomass Derived Heterogeneous and Homogeneous Catalysts)
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Open AccessArticle
Enzymatic Hydrolysis of Softwood Derived Paper Sludge by an In Vitro Recombinant Cellulase Cocktail for the Production of Fermentable Sugars
Catalysts 2020, 10(7), 775; https://doi.org/10.3390/catal10070775 - 11 Jul 2020
Cited by 1
Abstract
Paper sludge is an attractive biomass feedstock for bioconversion to ethanol due to its low cost and the lack of pretreatment required for its bioprocessing. This study assessed the use of a recombinant cellulase cocktail (mono-components: S. cerevisiae-derived PcBGL1B (BGL), Te [...] Read more.
Paper sludge is an attractive biomass feedstock for bioconversion to ethanol due to its low cost and the lack of pretreatment required for its bioprocessing. This study assessed the use of a recombinant cellulase cocktail (mono-components: S. cerevisiae-derived PcBGL1B (BGL), TeCel7A (CBHI), ClCel6A (CBHII) and TrCel5A (EGII) mono-component cellulase enzymes) for the efficient saccharification of softwood-derived paper sludge to produce fermentable sugars. The paper sludge mainly contained 74.3% moisture and 89.7% (per dry mass (DM)) glucan with a crystallinity index of 91.5%. The optimal protein ratio for paper sludge hydrolysis was observed at 9.4: 30.2: 30.2: 30.2% for BGL: CBHI: CBHII: EGII. At a protein loading of 7.5 mg/g DW paper sludge, the yield from hydrolysis was approximately 80%, based on glucan, with scanning electron microscopy micrographs indicating a significant alteration in the microfibril size (length reduced from ≥ 2 mm to 93 µm) of the paper sludge. The paper sludge hydrolysis potential of the Opt CelMix (formulated cellulase cocktail) was similar to the commercial Cellic CTec2® and Celluclast® 1.5 L cellulase preparations and better than Viscozyme® L. Low enzyme loadings (15 mg/g paper sludge) of the Opt CelMix and solid loadings ranging between 1 to 10% (w/v) rendered over 80% glucan conversion. The high glucose yields attained on the paper sludge by the low enzyme loading of the Opt CelMix demonstrated the value of enzyme cocktail optimisation on specific substrates for efficient cellulose conversion to fermentable sugars. Full article
(This article belongs to the Special Issue Biomass Derived Heterogeneous and Homogeneous Catalysts)
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Open AccessArticle
Biolubricants from Rapeseed and Castor Oil Transesterification by Using Titanium Isopropoxide as a Catalyst: Production and Characterization
Catalysts 2020, 10(4), 366; https://doi.org/10.3390/catal10040366 - 29 Mar 2020
Cited by 8
Abstract
The transesterification of rapeseed and castor oil methyl esters with different alcohols (2-ethyl-1-hexanol, 1-heptanol and 4-methyl-2-pentanol) and titanium isopropoxide as a catalyst, to produce biolubricants, was carried out. Parameters such as temperature, alcohol/methyl ester molar ratio, and catalyst concentration were studied to optimize [...] Read more.
The transesterification of rapeseed and castor oil methyl esters with different alcohols (2-ethyl-1-hexanol, 1-heptanol and 4-methyl-2-pentanol) and titanium isopropoxide as a catalyst, to produce biolubricants, was carried out. Parameters such as temperature, alcohol/methyl ester molar ratio, and catalyst concentration were studied to optimize the process. The reaction evolution was monitored with the decrease in FAME concentration by gas chromatography. In general, the reaction was almost complete in two hours, obtaining over 93% conversions. All the variables studied influenced on the reaction yields. Once the optimum conditions for the maximum conversion and minimum costs were selected, a characterization of the biolubricants obtained, along with the study of the influence of the kind of alcohol used, was carried out. The biolubricants had some properties that were better than mineral lubricants (flash points between 222 and 271 °C), needing the use of additives when they do not comply with the standards (low viscosity for rapeseed biolubricant, for instance). There was a clear influence of fatty acids of raw materials (oleic and ricinoleic acids as majority fatty acids in rapeseed and castor oil, respectively) and the structure of the alcohol used on the final features of the biolubricants. Full article
(This article belongs to the Special Issue Biomass Derived Heterogeneous and Homogeneous Catalysts)
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Open AccessArticle
Catalytic Performance of Bulk and Al2O3-Supported Molybdenum Oxide for the Production of Biodiesel from Oil with High Free Fatty Acids Content
Catalysts 2020, 10(2), 158; https://doi.org/10.3390/catal10020158 - 01 Feb 2020
Cited by 3
Abstract
Non-edible vegetable oils are characterized by high contents of free fatty acids (FFAs) that prevent from using the conventional basic catalysts for the production of biodiesel. In this work, solid acid catalysts are used for the simultaneous esterification and transesterification with methanol of [...] Read more.
Non-edible vegetable oils are characterized by high contents of free fatty acids (FFAs) that prevent from using the conventional basic catalysts for the production of biodiesel. In this work, solid acid catalysts are used for the simultaneous esterification and transesterification with methanol of the FFAs and triglycerides contained in sunflower oil acidified with oleic acid. Molybdenum oxide (MoO3), which has been seldom considered as a catalyst for the production of biodiesel, was used in bulk and alumina-supported forms. Results showed that bulk MoO3 is very active for both transesterification and esterification reactions, but it suffered from severe molybdenum leaching in the reaction medium. When supported on Al2O3, the MoO3 performance improved in terms of active phase utilization and stability though molybdenum leaching remained significant. The improvement of catalytic performance was ascribed to the establishment of MoO3-Al2O3 interactions that favored the anchorage of molybdenum to the support and the formation of new strong acidic centers, although this effect was offset by a decrease of specific surface area. It is concluded that the development of stable catalysts based on MoO3 offers an attractive route for the valorization of oils with high FFAs content. Full article
(This article belongs to the Special Issue Biomass Derived Heterogeneous and Homogeneous Catalysts)
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Open AccessArticle
Performance of a Ni-Cu-Co/Al2O3 Catalyst on in-situ Hydrodeoxygenation of Bio-derived Phenol
Catalysts 2019, 9(11), 952; https://doi.org/10.3390/catal9110952 - 14 Nov 2019
Cited by 3
Abstract
The in-situ hydrodeoxygenation of bio-derived phenol is an attractive routine for upgrading bio-oils. Herein, an active trimetallic Ni-Cu-Co/Al2O3 catalyst was prepared and applied in the in-situ hydrodeoxygenation of bio-derived phenol. Comparison with the monometallic Ni/Al2O3 catalyst and [...] Read more.
The in-situ hydrodeoxygenation of bio-derived phenol is an attractive routine for upgrading bio-oils. Herein, an active trimetallic Ni-Cu-Co/Al2O3 catalyst was prepared and applied in the in-situ hydrodeoxygenation of bio-derived phenol. Comparison with the monometallic Ni/Al2O3 catalyst and the bimetallic Ni-Co/Al2O3 and Ni-Cu/Al2O3 catalysts, the Ni-Cu-Co/Al2O3 catalyst exhibited the highest catalytic activity because of the formation of Ni-Cu-Co alloy on the catalyst characterized by using X-ray powder diffraction (XRD), temperature programmed reduction (TPR), N2 physisorption, scanning electron microscope (SEM), and transmission electron microscope (TEM). The phenol conversion of 100% and the cyclohexane yield of 98.3% could be achieved in the in-situ hydrodeoxygenation of phenol at 240 °C and 4 MPa N2 for 6 h. The synergistic effects of Ni with Cu and Co of the trimetallic Ni-Cu-Co/Al2O3 catalyst played a significant role in the in-situ hydrodeoxygenation process of phenol, which not only had a positive effect on the production of hydrogen but also owned an excellent hydrogenolysis activity to accelerate the conversion of cyclohexanol to cyclohexane. Furthermore, the catalyst also exhibited excellent recyclability and good potential for the upgrading of bio-oils. Full article
(This article belongs to the Special Issue Biomass Derived Heterogeneous and Homogeneous Catalysts)
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Open AccessArticle
Irrigation Combined with Aeration Promoted Soil Respiration through Increasing Soil Microbes, Enzymes, and Crop Growth in Tomato Fields
Catalysts 2019, 9(11), 945; https://doi.org/10.3390/catal9110945 - 11 Nov 2019
Cited by 3
Abstract
Soil respiration (Rs) is one of the major components controlling the carbon budget of terrestrial ecosystems. Aerated irrigation has been proven to increase Rs compared with the control, but the mechanisms of CO2 release remain poorly understood. The objective of this study [...] Read more.
Soil respiration (Rs) is one of the major components controlling the carbon budget of terrestrial ecosystems. Aerated irrigation has been proven to increase Rs compared with the control, but the mechanisms of CO2 release remain poorly understood. The objective of this study was (1) to test the effects of irrigation, aeration, and their interaction on Rs, soil physical and biotic properties (soil water-filled pore space, temperature, bacteria, fungi, actinomycetes, microbial biomass carbon, cellulose activity, dehydrogenase activity, root morphology, and dry biomass of tomato), and (2) to assess how soil physical and biotic variables control Rs. Therefore, three irrigation levels were included (60%, 80%, and 100% of full irrigation). Each irrigation level contained aeration and control. A total of six treatments were included. The results showed that aeration significantly increased total root length, dry biomass of leaf, stem, and fruit compared with the control (p < 0.05). The positive effect of irrigation on dry biomass of leaf, fruit, and root was significant (p < 0.05). With respect to the control, greater Rs under aeration (averaging 6.2% increase) was mainly driven by soil water-filled pore space, soil bacteria, and soil fungi. The results of this study are helpful for understanding the mechanisms of soil CO2 release under aerated subsurface drip irrigation. Full article
(This article belongs to the Special Issue Biomass Derived Heterogeneous and Homogeneous Catalysts)
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Open AccessFeature PaperArticle
Biodiesel Production from Castor oil by Two-Step Catalytic Transesterification: Optimization of the Process and Economic Assessment
Catalysts 2019, 9(10), 864; https://doi.org/10.3390/catal9100864 - 17 Oct 2019
Cited by 5
Abstract
The use of biodiesel and the requirement of improving its production in a more efficient and sustainable way are becoming more and more important. In this research work, castor oil was demonstrated to be an alternative feedstock for obtaining biodiesel. The production of [...] Read more.
The use of biodiesel and the requirement of improving its production in a more efficient and sustainable way are becoming more and more important. In this research work, castor oil was demonstrated to be an alternative feedstock for obtaining biodiesel. The production of biodiesel was optimized by the use of a two-step process. In this process, methanol and KOH (as a catalyst) were added in each step, and the glycerol produced during the first stage was removed before the second reaction. The reaction conditions were optimized, considering catalyst concentration and methanol/oil molar ratio for both steps. A mathematical model was obtained to predict the final ester content of the biodiesel. Optimal conditions (0.08 mol·L−1 and 0.01 mol·L−1 as catalyst concentration, 5.25:1 and 3:1 as methanol/oil molar ratio for first and second step, respectively) were established, taking into account the biodiesel quality and an economic analysis. This type of process allowed cost saving, since the amounts of methanol and catalyst were significantly reduced. An estimation of the final manufacturing cost of biodiesel production was carried out. Full article
(This article belongs to the Special Issue Biomass Derived Heterogeneous and Homogeneous Catalysts)
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Open AccessCommunication
One-Pot Solvent-Free Synthesis of N,N-Bis(2-Hydroxyethyl) Alkylamide from Triglycerides Using Zinc-Doped Calcium Oxide Nanospheroids as a Heterogeneous Catalyst
Catalysts 2019, 9(9), 774; https://doi.org/10.3390/catal9090774 - 14 Sep 2019
Cited by 3
Abstract
N,N-Bis(2-hydroxyethyl) alkylamide or fatty acid diethanolamides (FADs) were prepared from a variety of triglycerides using diethanolamine in the presence of different transition metal-doped CaO nanocrystalline heterogeneous catalysts. The Zn-doped Cao nanospheroids were found to be the most efficient heterogeneous catalyst, with complete [...] Read more.
N,N-Bis(2-hydroxyethyl) alkylamide or fatty acid diethanolamides (FADs) were prepared from a variety of triglycerides using diethanolamine in the presence of different transition metal-doped CaO nanocrystalline heterogeneous catalysts. The Zn-doped Cao nanospheroids were found to be the most efficient heterogeneous catalyst, with complete conversion of natural triglycerides to fatty acid diethanolamide in 30 min at 90 °C. The Zn/CaO nanoparticles were recyclable for up to six reaction cycles and showed complete conversion even at room temperature. The amidation reaction of natural triglycerides was found to follow the pseudo-first-order kinetic model, and the first-order rate constant was calculated as 0.171 min−1 for jatropha oil aminolysis. The activation energy (Ea) and pre-exponential factor (A) for the same reaction were found to be 47.8 kJ mol−1 and 4.75 × 108 min−1, respectively. Full article
(This article belongs to the Special Issue Biomass Derived Heterogeneous and Homogeneous Catalysts)
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Review

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Open AccessReview
Recent Developments in Metal-Based Catalysts for the Catalytic Aerobic Oxidation of 5-Hydroxymethyl-Furfural to 2,5-Furandicarboxylic Acid
Catalysts 2020, 10(1), 120; https://doi.org/10.3390/catal10010120 - 15 Jan 2020
Cited by 7
Abstract
Biomass can be used as an alternative feedstock for the production of fuels and valuable chemicals, which can alleviate the current global dependence on fossil resources. One of the biomass-derived molecules, 2,5-furandicarboxylic acid (FDCA), has attracted great interest due to its broad applications [...] Read more.
Biomass can be used as an alternative feedstock for the production of fuels and valuable chemicals, which can alleviate the current global dependence on fossil resources. One of the biomass-derived molecules, 2,5-furandicarboxylic acid (FDCA), has attracted great interest due to its broad applications in various fields. In particular, it is considered a potential substitute of petrochemical-derived terephthalic acid (PTA), and can be used for the preparation of valuable bio-based polyesters such as polyethylene furanoate (PEF). Therefore, significant attempts have been made for efficient production of FDCA and the catalytic chemical approach for FDCA production, typically from a biomass-derived platform molecule, 5-hydroxymethylfurfural (HMF), over metal catalysts is the focus of great research attention. In this review, we provide a systematic critical overview of recent progress in the use of different metal-based catalysts for the catalytic aerobic oxidation of HMF to FDCA. Catalytic performance and reaction mechanisms are described and discussed to understand the details of this reaction. Special emphasis is also placed on the base-free system, which is a more green process considering the environmental aspect. Finally, conclusions are given and perspectives related to further development of the catalysts are also provided, for the potential production of FDCA on a large scale in an economical and environmentally friendly manner. Full article
(This article belongs to the Special Issue Biomass Derived Heterogeneous and Homogeneous Catalysts)
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