Special Issue "Catalytic Liquefaction Processes of Biomass for Fuels and Chemicals"

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Chemical Processes and Systems".

Deadline for manuscript submissions: closed (31 May 2021) | Viewed by 5815

Special Issue Editor

Dr. Daniele Castello
E-Mail Website
Guest Editor
Department of Energy Technology, Aalborg University, Fredrik Bajers Vej 7K, 9220 Aalborg, Denmark
Interests: hydrothermal processes for biomass (liquefaction, gasification, carbonization); upgrading of biomass liquefaction products to drop-in fuels; catalytic pyrolysis of biomass

Special Issue Information

Dear Colleagues,

Utilizing biomass as a renewable source of carbon is one of the most exciting challenges of current research in chemical engineering. This has a special value in connection with the increasing concern on global warming, urging a reduction of the utilization of fossil resources in order to lower CO2 emissions.

Liquefaction processes are among the most important approaches for the production of transportation fuels and, possibly, renewable chemicals from biomass. They all involve processing biomass at high temperature, with the production of a liquid product (called bio-oil or biocrude) rich in organics, with a much higher energy density than the original biomass. This oil can in turn be upgraded to transportation fuels or be the starting point for the production of chemicals and materials. Pyrolysis has been one of the most investigated approaches for the production of liquid fuels from biomass, although the properties of the resulting bio-oils are usually far from those of transportation fuels. More recently, interesting perspectives have been offered by catalytic pyrolysis, where the adoption of proper catalysts results in much better properties of bio-oils, e.g., lower oxygen content and better boiling point distribution. Biomass liquefaction can also be successfully achieved through hydrothermal liquefaction (HTL), where the unique reaction environment with hot compress water and the addition of homogeneous or heterogeneous catalysts can result in high yields of high-quality biocrudes, even from low-value biomass feedstocks and organic waste.

This Special Issue aims at gathering recent, high-quality research contributions in the field of catalytic liquefaction processes for biomass, for the production of sustainable biofuels and/or chemicals. Possible topics include (but are not limited to):

  • Experimental studies on catalytic pyrolysis or catalytic hydrothermal liquefaction;
  • Comparison between catalytic and noncatalytic biomass liquefaction processes;
  • Upgrading of bio-oils from catalytic liquefaction processes to final fuels and chemicals;
  • Blending and co-refining of bio-oils from catalytic liquefaction processes for drop-in fuels;
  • Development of novel catalysts for thermochemical liquefaction;
  • Case studies on pilot or demonstration scale plants;
  • Modeling studies and technoeconomic evaluations.

I hope that you may find this Special Issue of interest for your research and look forward to receiving your contributions.

Dr. Daniele Castello
Guest Editor

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. Processes 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

  • biomass
  • catalytic hydrothermal liquefaction
  • catalytic pyrolysis
  • catalysis
  • upgrading
  • biofuels
  • renewable chemicals

Published Papers (6 papers)

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Research

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Article
An In-Depth Process Model for Fuel Production via Hydrothermal Liquefaction and Catalytic Hydrotreating
Processes 2021, 9(7), 1172; https://doi.org/10.3390/pr9071172 - 05 Jul 2021
Viewed by 1019
Abstract
One of the more promising technologies for future renewable fuel production from biomass is hydrothermal liquefaction (HTL). Although enormous progress in the context of continuous experiments on demonstration plants has been made in the last years, still many research questions concerning the understanding [...] Read more.
One of the more promising technologies for future renewable fuel production from biomass is hydrothermal liquefaction (HTL). Although enormous progress in the context of continuous experiments on demonstration plants has been made in the last years, still many research questions concerning the understanding of the HTL reaction network remain unanswered. In this study, a unique process model of an HTL process chain has been developed in Aspen Plus® for three feedstock, microalgae, sewage sludge and wheat straw. A process chain consisting of HTL, hydrotreatment (HT) and catalytic hydrothermal gasification (cHTG) build the core process steps of the model, which uses 51 model compounds representing the hydrolysis products of the different biochemical groups lipids, proteins, carbohydrates, lignin, extractives and ash for modeling the biomass. Two extensive reaction networks of 272 and 290 reactions for the HTL and HT process step, respectively, lead to the intermediate biocrude (~200 model compounds) and the final upgraded biocrude product (~130 model compounds). The model can reproduce important characteristics, such as yields, elemental analyses, boiling point distribution, product fractions, density and higher heating values of experimental results from continuous experiments as well as literature values. The model can be applied as basis for techno-economic and environmental assessments of HTL fuel production, and may be further developed into a predictive yield modeling tool. Full article
(This article belongs to the Special Issue Catalytic Liquefaction Processes of Biomass for Fuels and Chemicals)
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Article
Demineralization of Miscanthus Biocrude Obtained from Catalytic Hydrothermal Liquefaction: Conditioning through Acid Washing
Processes 2021, 9(6), 1035; https://doi.org/10.3390/pr9061035 - 12 Jun 2021
Cited by 2 | Viewed by 1013
Abstract
In this contribution, we successfully applied demineralization (i.e., solvent-assisted separation and acid washing) for the removal of carbonaceous solids and inorganics from a biocrude obtained from the catalytic hydrothermal liquefaction (HTL) of Miscanthus. The experimental results of all six employed acids showed [...] Read more.
In this contribution, we successfully applied demineralization (i.e., solvent-assisted separation and acid washing) for the removal of carbonaceous solids and inorganics from a biocrude obtained from the catalytic hydrothermal liquefaction (HTL) of Miscanthus. The experimental results of all six employed acids showed that 0.1 M H2SO4 was the most effective and significantly reduced metallic (Fe by 93.9%, <15 µg/g and Mg by 95.6%, 2.1 µg/g) and ash content (by 92.7% to 337 µg/g) from the already filtered biocrude. The utilized demineralizing agents caused a loss of nitrogen and of organic carbon (1% total organic carbon (TOC) and 0.058% total nitrogen (TN) in 0.1 M H2SO4). Gas chromatography-mass spectrometry (GC–MS) results clarified the nature of this loss, showing that 54% of ketones and 39% of alcohols were removed when 0.1 M H2SO4 was employed. Furthermore, FT-IR spectra remained the same before and after acid washing without affecting any functional groups. This work therefore proposes demineralization as a viable route for the removal of high inorganic content from lignocellulosic HTL biocrudes. Full article
(This article belongs to the Special Issue Catalytic Liquefaction Processes of Biomass for Fuels and Chemicals)
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Article
Economic and Environmental Assessment of Catalytic and Thermal Pyrolysis Routes for Fuel Production from Lignocellulosic Biomass
Processes 2020, 8(12), 1612; https://doi.org/10.3390/pr8121612 - 07 Dec 2020
Viewed by 694
Abstract
Meeting the transport needs of a growing world population makes it imperative to develop renewable and sustainable routes to production of liquid fuels. With a market-driven economic structure and pressing environmental issues, it is essential that these new routes provide environmental benefits while [...] Read more.
Meeting the transport needs of a growing world population makes it imperative to develop renewable and sustainable routes to production of liquid fuels. With a market-driven economic structure and pressing environmental issues, it is essential that these new routes provide environmental benefits while being economically viable. Conversion of second-generation lignocellulosic biomass resources to fuels via pyrolysis represents an important technological route. In this article, we report comparative assessment of the economic and lifecycle environmental aspects for catalytic and thermal pyrolysis. The goal of this assessment is two-fold: one is to understand the potential of this conversion route via the catalytic and thermal processes and second is to provide feedback for further development of catalysts for various stages of this conversion. The complete assessment is interdisciplinary in nature and connects the laboratory experiments with contextual sustainability assessment. Three catalytic and one thermal pyrolysis processes are analyzed using this assessment approach. Subject to the model choices and data inputs, the results, which consider quality of the oil product, show that biofuels produced using catalytic and thermal routes are rather expensive compared to gasoline. But at the same time, they provide significant greenhouse gas emission savings and can lead to lower CO2 abatement costs compared to the first-generation ethanol that is used currently. With one of the product scenarios of hydrotreated (HT) oil, the abatements costs are estimated to be 51% of those associated with first-generation ethanol. Additional product scenarios with developments in catalysts show potential to further reduce abatement costs significantly to below 100 EUR per metric tonne of CO2 equivalents. Using scenario analysis, the results help us to understand specific areas for development of novel catalysts. At the same time, the results demonstrate the trade-offs associated with the variety and complexity of technical factors associated with the pyrolysis routes. The study highlights the challenges and the promises of catalytic and thermal pyrolysis for production of high-quality biofuels produced via a sustainable production route. Full article
(This article belongs to the Special Issue Catalytic Liquefaction Processes of Biomass for Fuels and Chemicals)
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Article
Comparative Technical Process and Product Assessment of Catalytic and Thermal Pyrolysis of Lignocellulosic Biomass
Processes 2020, 8(12), 1600; https://doi.org/10.3390/pr8121600 - 04 Dec 2020
Cited by 3 | Viewed by 730
Abstract
Availability of sustainable transportation fuels in future hinges on the use of lignocellulosic resources for production of biofuels. The process of biomass pyrolysis can be used to convert solid biomass resources into liquid fuels. In this study, laboratory experiments and process simulations were [...] Read more.
Availability of sustainable transportation fuels in future hinges on the use of lignocellulosic resources for production of biofuels. The process of biomass pyrolysis can be used to convert solid biomass resources into liquid fuels. In this study, laboratory experiments and process simulations were combined to gain insight into the technical performance of catalytic and thermal pyrolysis processes. Waste pinewood was used as a feedstock for the processes. The pyrolysis took place at 500 °C and employs three different catalysts, in the case of the catalytic processes. A process model was developed with Aspen Plus and a wide range of representative components of bio-oil were used to model the properties of the bio-oil blend. The results of the process model calculations show that catalytic pyrolysis process produces bio-oil of superior quality. Different technical process scenarios were explored based on the properties of the bio-oil after separation of water-soluble components, with the intention of producing a blendable or stand-alone product. It was found that—depending on the bio-oil requirements—sufficient hydrogen can be made available from the aqueous fraction to further treat the organic fraction to the desired extent. The resulting organic fractions are suitable candidates for blending with conventional fuels. The analysis results are used to provide guidance for catalyst development. Full article
(This article belongs to the Special Issue Catalytic Liquefaction Processes of Biomass for Fuels and Chemicals)
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Review

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Review
The Role of Catalysts in Biomass Hydrothermal Liquefaction and Biocrude Upgrading
Processes 2022, 10(2), 207; https://doi.org/10.3390/pr10020207 - 21 Jan 2022
Cited by 2 | Viewed by 886
Abstract
Hydrothermal liquefaction (HTL) of biomass is establishing itself as one of the leading technologies for the conversion of virtually any type of biomass feedstock into drop-in biofuels and renewable materials. Several catalysis strategies have been proposed for this process to increase the yields [...] Read more.
Hydrothermal liquefaction (HTL) of biomass is establishing itself as one of the leading technologies for the conversion of virtually any type of biomass feedstock into drop-in biofuels and renewable materials. Several catalysis strategies have been proposed for this process to increase the yields of the product (biocrude) and/or to obtain a product with better properties in light of the final use. A number of different studies are available in the literature nowadays, where different catalysts are utilized within HTL including both homogeneous and heterogeneous approaches. Additionally, catalysis plays a major role in the upgrading of HTL biocrude into final products, in which field significant developments have been observed in recent times. This review has the ambition to summarize the different available information to draw an updated overall picture of catalysis applied to HTL. The different catalysis strategies are reviewed, highlighting the specific effect of each kind of catalyst on the yields and properties of the HTL products, by comparing them with the non-catalyzed case. This allows for drawing quantitative conclusions on the actual effectiveness of each catalyst, in relation to the different biomass processed. Additionally, the pros and cons of each different catalysis approach are discussed critically, identifying new challenges and future directions of research. Full article
(This article belongs to the Special Issue Catalytic Liquefaction Processes of Biomass for Fuels and Chemicals)
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Review
The Role of Ionic Liquids on Biomass Liquefaction—A Short Review of the Recent Advances
Processes 2021, 9(7), 1214; https://doi.org/10.3390/pr9071214 - 15 Jul 2021
Cited by 2 | Viewed by 660
Abstract
Biomass is recognised as one of the most attractive feedstocks among the alternative resources, having a high potential for the sustainable production of valuable chemicals and biofuels. Due to its abundance, convenience, carbon neutrality and eco-friendliness, biomass is believed to positively impact the [...] Read more.
Biomass is recognised as one of the most attractive feedstocks among the alternative resources, having a high potential for the sustainable production of valuable chemicals and biofuels. Due to its abundance, convenience, carbon neutrality and eco-friendliness, biomass is believed to positively impact the current environmental crisis caused by the extensive use of petroleum resources. For this reason, the search for processes that can convert this feedstock, resolving some inherent drawbacks, is needed. Biomass liquefaction using ionic liquids (ILs) as catalysts has received appreciable attention in renewable fuels and chemicals production. With the potential for a substantial number of anion and cation pairings, ILs can be an attractive medium towards reusability and sustainability for these processes due to the unique and tunable combinations of their functional groups-and, therefore, their properties. In this review, several studies using ILs in biomass liquefaction are compared and discussed. With a particular emphasis on the last five years, advantages and disadvantages will be discussed using this class of liquids addressing essential issues such as yields, reusability and conversion, among others. Full article
(This article belongs to the Special Issue Catalytic Liquefaction Processes of Biomass for Fuels and Chemicals)
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