Research

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18 pages, 2015 KiB

Open AccessArticle

Kinetic Modelling and Experimental Studies for the Effects of Fe²⁺ Ions on Xylan Hydrolysis with Dilute-Acid Pretreatment and Subsequent Enzymatic Hydrolysis

by Hui Wei, Xiaowen Chen, Joseph Shekiro, Erik Kuhn, Wei Wang, Yun Ji, Evguenii Kozliak, Michael E. Himmel and Melvin P. Tucker

Catalysts 2018, 8(1), 39; https://doi.org/10.3390/catal8010039 - 20 Jan 2018

Cited by 16 | Viewed by 6041

Abstract

High-temperature (150–170 °C) pretreatment of lignocellulosic biomass with mineral acids is well established for xylan breakdown. Fe²⁺ is known to be a cocatalyst of this process although kinetics of its action remains unknown. The present work addresses the effect of ferrous ion [...] Read more.

High-temperature (150–170 °C) pretreatment of lignocellulosic biomass with mineral acids is well established for xylan breakdown. Fe²⁺ is known to be a cocatalyst of this process although kinetics of its action remains unknown. The present work addresses the effect of ferrous ion concentration on sugar yield and degradation product formation from corn stover for the entire two-step treatment, including the subsequent enzymatic cellulose hydrolysis. The feedstock was impregnated with 0.5% acid and 0.75 mM iron cocatalyst, which was found to be optimal in preliminary experiments. The detailed kinetic data of acid pretreatment, with and without iron, was satisfactorily modelled with a four-step linear sequence of first-order irreversible reactions accounting for the formation of xylooligomers, xylose and furfural as intermediates to provide the values of Arrhenius activation energy. Based on this kinetic modelling, Fe²⁺ turned out to accelerate all four reactions, with a significant alteration of the last two steps, that is, xylose degradation. Consistent with this model, the greatest xylan conversion occurred at the highest severity tested under 170 °C/30 min with 0.75 mM Fe²⁺, with a total of 8% xylan remaining in the pretreated solids, whereas the operational conditions leading to the highest xylose monomer yield, 63%, were milder, 150 °C with 0.75 mM Fe²⁺ for 20 min. Furthermore, the subsequent enzymatic hydrolysis with the prior addition of 0.75 mM of iron(II) increased the glucose production to 56.3% from 46.3% in the control (iron-free acid). The detailed analysis indicated that conducting the process at lower temperatures yet long residence times benefits the yield of sugars. The above kinetic modelling results of Fe²⁺ accelerating all four reactions are in line with our previous mechanistic research showing that the pretreatment likely targets multiple chemistries in plant cell wall polymer networks, including those represented by the C–O–C and C–H bonds in cellulose, resulting in enhanced sugar solubilization and digestibility. Full article

(This article belongs to the Special Issue Catalytic Sustainable Processes in Biorefineries)

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2343 KiB

Open AccessArticle

Synthesis of Biolubricant Basestocks from Epoxidized Soybean Oil

by Rosa Turco, Riccardo Tesser, Rosa Vitiello, Vincenzo Russo, Salvatore Andini and Martino Di Serio

Catalysts 2017, 7(10), 309; https://doi.org/10.3390/catal7100309 - 19 Oct 2017

Cited by 37 | Viewed by 5475

Abstract

This work deals with the preparation of biolubricant basestocks through the ring-opening reaction of epoxidized soybean oil (ESO) by alcohols in presence of solid acid catalysts (SAC-13 resin). To this end, different experimental runs were carried out in a lab-scale reactor, analyzing the [...] Read more.

This work deals with the preparation of biolubricant basestocks through the ring-opening reaction of epoxidized soybean oil (ESO) by alcohols in presence of solid acid catalysts (SAC-13 resin). To this end, different experimental runs were carried out in a lab-scale reactor, analyzing the effect of the alcohol (methanol, ethanol, 2-propanol, 2-butanol), catalyst mass loading (from 1 to 10 wt % with respect to the oil mass) and operating temperature (60–90 °C). The main focus of investigation was oxirane conversion. The study was complemented by FT-IR, ¹H NMR and kinematic viscosity characterization of the different products of the ring-opening reaction. Experimental conversion data were fitted through a suitable kinetic model. Values of the best-fitting parameters in terms of rate constant, activation energy and catalyst reaction order were obtained, and were potentially useful for the design of an industrial process. Full article

(This article belongs to the Special Issue Catalytic Sustainable Processes in Biorefineries)

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4397 KiB

Open AccessArticle

Alcohol Dehydrogenation on Kraft Lignin-Derived Chars with Surface Basicity

by Francisco J. García-Mateos, Imane Moulefera, Juana M. Rosas, Abdelghani Benyoucef, José Rodríguez-Mirasol and Tomás Cordero

Catalysts 2017, 7(10), 308; https://doi.org/10.3390/catal7100308 - 19 Oct 2017

Cited by 19 | Viewed by 4232

Abstract

The properties of lignin and its potential as a renewable source make it an ideal precursor for carbon products. Specifically, the high content of Na observed in Kraft lignin makes this industrial by-product an interesting precursor for the preparation of catalysts for different [...] Read more.

The properties of lignin and its potential as a renewable source make it an ideal precursor for carbon products. Specifically, the high content of Na observed in Kraft lignin makes this industrial by-product an interesting precursor for the preparation of catalysts for different applications. In this work, basic activated carbons with different textural properties and surface chemistry were obtained from Kraft lignin by direct carbonization at various temperatures. The influence of a further washing treatment and partial gasification with CO₂ was also evaluated. The carbon catalysts were tested as catalysts for the alcohol decomposition reaction. In this sense, 2-propanol, a molecule widely used for testing the acidic-basic character of heterogeneous catalysts, was selectively transformed into acetone, meanwhile, ethanol and methanol yielded mainly acetaldehyde and formaldehyde, respectively. Full article

(This article belongs to the Special Issue Catalytic Sustainable Processes in Biorefineries)

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2827 KiB

Open AccessArticle

Synthesis of Renewable Diesel Range Alkanes by Hydrodeoxygenation of Palmitic Acid over 5% Ni/CNTs under Mild Conditions

by Yanan Duan, Ranran Ding, Yanchun Shi, Xiao Fang, Husheng Hu, Mingde Yang and Yulong Wu

Catalysts 2017, 7(3), 81; https://doi.org/10.3390/catal7030081 - 09 Mar 2017

Cited by 13 | Viewed by 5294

Abstract

Recently, the catalytic upgrading of bio-oil to renewable diesel has been attracting more and more attention. In the current paper, carbon nanotube (CNT)-supported nickel catalysts, namely, 5% Ni/CNTs, were prepared for liquid hydrocarbon production through the deoxygenation of palmitic acid, the model compound [...] Read more.

Recently, the catalytic upgrading of bio-oil to renewable diesel has been attracting more and more attention. In the current paper, carbon nanotube (CNT)-supported nickel catalysts, namely, 5% Ni/CNTs, were prepared for liquid hydrocarbon production through the deoxygenation of palmitic acid, the model compound of bio-oil under a mild condition of 240 °C reaction temperature and 2 MPa H₂ pressure. The experimental results revealed that the main reaction product was pentadecane (yield of 89.64%) at an optimum palmitic acid conversion of 97.25% via the hydrodecarbonylation (HDC) process. The deoxygenation mechanism for palmitic acid conversion was also investigated. This study provides technical parameters and a theoretical basis for further industrialization in the bio-oil upgrading process. Full article

(This article belongs to the Special Issue Catalytic Sustainable Processes in Biorefineries)

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Review

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3695 KiB

Open AccessFeature PaperReview

Advances in Base-Free Oxidation of Bio-Based Compounds on Supported Gold Catalysts

by Robert Wojcieszak, Camila P. Ferraz, Jin Sha, Sarah Houda, Liane M. Rossi and Sébastien Paul

Catalysts 2017, 7(11), 352; https://doi.org/10.3390/catal7110352 - 21 Nov 2017

Cited by 46 | Viewed by 6674

Abstract

The oxidation of bio-based molecules in general, and of carbohydrates and furanics in particular, is a highly attractive process. The catalytic conversion of renewable compounds is of high importance. Acids and other chemical intermediates issued from oxidation processes have many applications related, especially, [...] Read more.

The oxidation of bio-based molecules in general, and of carbohydrates and furanics in particular, is a highly attractive process. The catalytic conversion of renewable compounds is of high importance. Acids and other chemical intermediates issued from oxidation processes have many applications related, especially, to food and detergents, as well as to pharmaceutics, cosmetics, and the chemical industry. Until now, the oxidation of sugars, furfural, or 5-hydroxymethylfurfural has been mainly conducted through biochemical processes or with strong inorganic oxidants. The use of these processes very often presents many disadvantages, especially regarding products separation and selectivity control. Generally, the oxidation is performed in batch conditions using an appropriate catalyst and a basic aqueous solution (pH 7–9), while bubbling oxygen or air through the slurry. However, there is a renewed interest in working in base-free conditions to avoid the production of salts. Actually, this gives direct access to different acids or diacids without laborious product purification steps. This review focuses on processes applying gold-based catalysts, and on the catalytic properties of these systems in the base-free oxidation of important compounds: C5–C6 sugars, furfural, and 5-hydroxymethylfurfural. A better understanding of the chemical and physical properties of the catalysts and of the operating conditions applied in the oxidation reactions is essential. For this reason, in this review we put emphasis on these most impacting factors. Full article

(This article belongs to the Special Issue Catalytic Sustainable Processes in Biorefineries)

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4448 KiB

Open AccessReview

A Review on the Production and Purification of Biomass-Derived Hydrogen Using Emerging Membrane Technologies

by Hang Yin and Alex C.K. Yip

Catalysts 2017, 7(10), 297; https://doi.org/10.3390/catal7100297 - 06 Oct 2017

Cited by 56 | Viewed by 8695

Abstract

Hydrogen energy systems are recognized as a promising solution for the energy shortage and environmental pollution crises. To meet the increasing demand for hydrogen, various possible systems have been investigated for the production of hydrogen by efficient and economical processes. Because of its [...] Read more.

Hydrogen energy systems are recognized as a promising solution for the energy shortage and environmental pollution crises. To meet the increasing demand for hydrogen, various possible systems have been investigated for the production of hydrogen by efficient and economical processes. Because of its advantages of being renewable and environmentally friendly, biomass processing has the potential to become the major hydrogen production route in the future. Membrane technology provides an efficient and cost-effective solution for hydrogen separation and greenhouse gas capture in biomass processing. In this review, the future prospects of using gas separation membranes for hydrogen production in biomass processing are extensively addressed from two perspectives: (1) the current development status of hydrogen separation membranes made of different materials and (2) the feasibility of using these membranes for practical applications in biomass-derived hydrogen production. Different types of hydrogen separation membranes, including polymeric membranes, dense metal membranes, microporous membranes (zeolite, metal-organic frameworks (MOFs), silica, etc.) are systematically discussed in terms of their fabrication methods, gas permeation performance, structure stability properties, etc. In addition, the application feasibility of these membranes in biomass processing is assessed from both practical and economic perspectives. The benefits and possibilities of using membrane reactors for hydrogen production in biomass processing are also discussed. Lastly, we summarize the limitations of the currently available hydrogen membranes as well as the gaps between research achievements and industrial application. We also propose expected research directions for the future development of hydrogen gas membrane technology. Full article

(This article belongs to the Special Issue Catalytic Sustainable Processes in Biorefineries)

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10246 KiB

Open AccessFeature PaperReview

Hydrodeoxygenation of Lignin-Derived Phenols: From Fundamental Studies towards Industrial Applications

by Päivi Mäki-Arvela and Dmitry Yu. Murzin

Catalysts 2017, 7(9), 265; https://doi.org/10.3390/catal7090265 - 07 Sep 2017

Cited by 82 | Viewed by 10552

Abstract

Hydrodeoxygenation (HDO) of bio-oils, lignin and their model compounds is summarized in this review. The main emphasis is put on elucidating the reaction network, catalyst stability and time-on-stream behavior, in order to better understand the prerequisite for industrial utilization of biomass in HDO [...] Read more.

Hydrodeoxygenation (HDO) of bio-oils, lignin and their model compounds is summarized in this review. The main emphasis is put on elucidating the reaction network, catalyst stability and time-on-stream behavior, in order to better understand the prerequisite for industrial utilization of biomass in HDO to produce fuels and chemicals. The results have shown that more oxygenated feedstock, selection of temperature and pressure as well as presence of certain catalyst poisons or co-feed have a prominent role in the HDO of real biomass. Theoretical considerations, such as density function theory (DFT) calculations, were also considered, giving scientific background for the further development of HDO of real biomass. Full article

(This article belongs to the Special Issue Catalytic Sustainable Processes in Biorefineries)

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4214 KiB

Open AccessReview

Catalytic Processes for Utilizing Carbohydrates Derived from Algal Biomass

by Sho Yamaguchi, Ken Motokura, Kan Tanaka and Sousuke Imamura

Catalysts 2017, 7(5), 163; https://doi.org/10.3390/catal7050163 - 19 May 2017

Cited by 8 | Viewed by 5281

Abstract

The high productivity of oil biosynthesized by microalgae has attracted increasing attention in recent years. Due to the application of such oils in jet fuels, the algal biosynthetic pathway toward oil components has been extensively researched. However, the utilization of the residue from [...] Read more.

The high productivity of oil biosynthesized by microalgae has attracted increasing attention in recent years. Due to the application of such oils in jet fuels, the algal biosynthetic pathway toward oil components has been extensively researched. However, the utilization of the residue from algal cells after oil extraction has been overlooked. This residue is mainly composed of carbohydrates (starch), and so we herein describe the novel processes available for the production of useful chemicals from algal biomass-derived sugars. In particular, this review highlights our latest research in generating lactic acid and levulinic acid derivatives from polysaccharides and monosaccharides using homogeneous catalysts. Furthermore, based on previous reports, we discuss the potential of heterogeneous catalysts for application in such processes. Full article

(This article belongs to the Special Issue Catalytic Sustainable Processes in Biorefineries)

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