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Spruce pretreatment for thermal application: Water, alkaline, and diluted acid hydrolysis
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.ORCID iD: 0000-0002-1837-5439
2012 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 26, no 10, 6426-6431 p.Article in journal (Refereed) Published
Abstract [en]

Hydrolysis a process that involves a separation of the main components of lignocellulosic material (LCM) primarily developed for ethanol production was applied in this work to upgrade biomass for thermal application. The purpose of the pretreatment was to remove hemicellulose and alkali metals and consequently increase the energy content of the biomass and improve the fuel properties. Freshly chopped (2-10 mm) spruce (Picea abies) samples were hydrolyzed (liquid/solid ratio of 800 mL/80 g), using water, diluted acid, and sodium hydroxide in a rotating autoclave at 180 2 ̊C for 150 and 350 min. Several analyses, such as proximate and ultimate analyses, ash composition and fusibility characteristics, and thermogravimetric analysis under pure nitrogen, were performed. Despite the reduction of mass and energy yields with increment of the severity factor, a significant increment of the higher heating value and ash quality was achieved, revealing that hydrolysis using water or diluted acid is a promising method to upgrade biomass as fuel. For alkaline treatment, a huge degradation on the quality of the ash was observed.

Place, publisher, year, edition, pages
2012. Vol. 26, no 10, 6426-6431 p.
Keyword [en]
Acid hydrolysis, Alkaline treatment, Ash composition, Energy content, Energy yields, Ethanol production, Fuel properties, Higher heating value, Lignocellulosic material, Picea abies, Pre-Treatment, Severity factor, Sodium hydroxides, Thermal applications, Ultimate analysis
National Category
Energy Systems
URN: urn:nbn:se:kth:diva-105426DOI: 10.1021/ef301167vISI: 000309902200040ScopusID: 2-s2.0-84867650070OAI: diva2:571071

QC 20121121

Available from: 2012-11-21 Created: 2012-11-21 Last updated: 2015-02-02Bibliographically approved
In thesis
1. Mild Wet Torrefaction and Characterization of Woody Biomass from Mozambique for Thermal Applications
Open this publication in new window or tab >>Mild Wet Torrefaction and Characterization of Woody Biomass from Mozambique for Thermal Applications
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Mozambique has vast forestry resources and also considerable biomass waste material such as bagasse, rice husks, sawdust, coconut husks and shells, cashew nut shell and lump charcoal waste. The potential of the total residues from the agricultural sector and the forest industry is estimated to be approximately 13 PJ. This amount of energy covers totally the production of charcoal which amounted to approximately 12.7 PJ in 2006. Although biomass is an attractive renewable source of energy, it is generally difficult to handle, transport, storage and use due to its lower homogeneity, its lower energy density and the presence of non-combustible inorganic constituents, which leads to different problems in energy conversion units such as deposition, sintering, agglomeration, fouling and corrosion. Therefore, a pretreatment of the biomass to solve these problems could lead to a change of current biomass utilization situation. The aim of this study is to convert Mozambican woody biomass residue into a solid biochar that resembles low-grade coal.

In this work the current energy situation in Mozambique has been reviewed, and the available and potential renewable sources including residues from agricultural crops and forest industry as energy have been assessed. It was found that the country is endowed with great potential for biofuel, solar, hydro and wind energy production. However, the production today is still far from fulfilling the energy needs of the country, and the majority of people are still not benefiting from these resources. Charcoal and firewood are still the main sources of energy and will continue to play a very important role in the near future. Additionally, enormous amounts of energy resources are wasted, especially in the agricultural sector. These residues are not visible on national energy statistics. The chemical composition and the fuelwood value index (FVI) showed that by failing to efficiently utilise residues from Afzelia quanzensis, Millettia stuhlmannii and Pterocarpus angolensis, an opportunity to reduce some of the energy related problems is missed. An evaluation of effect of a mild wet torrefaction pretreatment showed that the chemical composition of the biochar is substantially different than the feedstock. The use of diluted acid as catalysts improves the biochar quality, namely in terms of the energy density and ash characteristics; however, the increment of the S content in the final product should be considered for market acceptance (because the fuels have a maximum allowance for S concentration). The thermal behaviour of the untreated and treated biomass was also investigated. The pyrolytic products of umbila and spruce were affected by the treatment and catalyst in terms of yield and composition of the vapours.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. v, 71 p.
Biomass, Wet torrefaction, Fast Pyrolysis, kinetics, Catalyst
National Category
Engineering and Technology Chemical Process Engineering
urn:nbn:se:kth:diva-159476 (URN)978-91-7595-429-5 (ISBN)
Public defence
2015-02-20, Sal F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)

QC 20150202

Available from: 2015-02-02 Created: 2015-02-02 Last updated: 2015-02-02Bibliographically approved

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