University of Massachusetts -Amherst Pyrolysis Oils: Characterization, Stability Analysis, and Catalytic Upgrading to Fuels and Chemicals (original) (raw)
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Bio-Oil: The Next-Generation Source of Chemicals
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Bio-oil, although rich in chemical species, is primarily used as fuel oil, due to its greater calorific power when compared to the biomass from which it is made. The incomplete understanding of how to explore its chemical potential as a source of value-added chemicals and, therefore, a supply of intermediary chemical species is due to the diverse composition of bio-oil. Being biomass-based, making it subject to composition changes, bio-oil is obtained via different processes, the two most common being fast pyrolysis and hydrothermal liquefaction. Different methods result in different bio-oil compositions even from the same original biomass. Understanding which biomass source and process results in a particular chemical makeup is of interest to those concerned with the refinement or direct application in chemical reactions of bio-oil. This paper presents a summary of published bio-oil production methods, origin biomass, and the resulting composition.
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Bio-fuels are important because they replace petroleum fuels. There are many benefits for the environment, economy and consumers in using bio-fuels. Bio-oil can be used as a substitute for fossil fuels to generate heat, power and/or chemicals. Upgrading of bio-oil to a transportation fuel is technically feasible, but needs further development. Bio-fuels are made from biomass through thermochemical processes such as pyrolysis, gasification, liquefaction and supercritical fluid extraction or biochemical. Biochemical conversion of biomass is completed through alcoholic fermentation to produce liquid fuels and anaerobic digestion or fermentation, resulting in biogas. In wood derived pyrolysis oil, specific oxygenated compounds are present in relatively large amounts. Basically, the recovery of pure compounds from the complex bio-oil is technically feasible but probably economically unattractive because of the high costs for recovery of the chemical and its low concentration in the oil.
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Biofuels can potentially address greenhouse gas emissions and related environmental issues caused by fossil fuels. Fossil fuels such as gasoline and diesel have been the preferred fuels for the automotive sector. Although promising, crude bio-oil derived from pyrolysis and liquefaction of waste biomass does not meet the fuel standards for direct use in combustion engines and power plants. Bio-oil has a considerable amount of water as well as components containing oxygen, nitrogen, sulfur, metals, and aromatic compounds. Such components add many undesired properties to bio-oil such as high viscosity, low fluidity, low heating value, greater acidity, and thermal instability. This chapter is an introductory review of some notable catalytic and noncatalytic bio-oil upgrading technologies that make them compatible with transportation fuels. The catalytic upgrading technologies reviewed include hydrogenation, hydrocracking, esterification, and transesterification. The noncatalytic upgrading techniques reviewed are emulsification, solvent addition, supercritical fluids, and electrochemical stabilization. The strengths, weaknesses, opportunities, and threats for each of these bio-oil upgrading technologies are comprehensively discussed along with their operational mechanisms and challenges.
Catalytic conversion of biomass-derived oils to fuels and chemicals
1993
To my wife Flora and daughter Fraikua for their sacrifice, encouragement and love COPYRIGHT The author •has agreed that the Library, .university of Saskatchewan, may make this thesis freely available for inspection.~oreover, the author has agreed that permission for extensive copying of this thesis for scholarly purposes may be granted by the professors who supervised the thesis work recorded herein, or, in their absence, by the Head of the Department of Chemical Engineering or the Dean of the College of Graduate Studies. It is understood that due recognition will be given to the author of this thesis and to the University of Saskatchewan in any use of material of this thesis. Copying or pUblication or any other use of the thesis for financial gain without approval by the University of Saskatchewan and the author's permission is prohibited.
A review of catalytic upgrading of bio-oil to engine fuels
As the oil reserves are depleting the need of an alternative fuel source is becoming increasingly apparent. One prospective method for producing fuels in the future is conversion of biomass into bio-oil and then upgrading the bio-oil over a catalyst, this method is the focus of this review article. Bio-oil production can be facilitated through flash pyrolysis, which has been identified as one of the most feasible routes. The bio-oil has a high oxygen content and therefore low stability over time and a low heating value. Upgrading is desirable to remove the oxygen and in this way make it resemble crude oil. Two general routes for bio-oil upgrading have been considered: hydrodeoxygenation (HDO) and zeolite cracking. HDO is a high pressure operation where hydrogen is used to exclude oxygen from the bio-oil, giving a high grade oil product equivalent to crude oil. Catalysts for the reaction are traditional hydrodesulphurization (HDS) catalysts, such as Co–MoS 2 /Al 2 O 3 , or metal catalysts, as for example Pd/C. However, catalyst lifetimes of much more than 200 h have not been achieved with any current catalyst due to carbon deposition. Zeolite cracking is an alternative path, where zeolites, e.g. HZSM-5, are used as catalysts for the deoxygenation reaction. In these systems hydrogen is not a requirement, so operation is performed at atmospheric pressure. However, extensive carbon deposition results in very short catalyst lifetimes. Furthermore a general restriction in the hydrogen content of the bio-oil results in a low H/C ratio of the oil product as no additional hydrogen is supplied. Overall, oil from zeolite cracking is of a low grade, with heating values approximately 25% lower than that of crude oil. Of the two mentioned routes, HDO appears to have the best potential, as zeolite cracking cannot produce fuels of acceptable grade for the current infrastructure. HDO is evaluated as being a path to fuels in a grade and at a price equivalent to present fossil fuels, but several tasks still have to be addressed within this process. Catalyst development, understanding of the carbon forming mechanisms, understanding of the kinetics, elucidation of sulphur as a source of deactivation, evaluation of the requirement for high pressure, and sustainable sources for hydrogen are all areas which have to be elucidated before commercialisation of the process.
2014
Bio-oil is a liquid fuel that can be produced from various lignocellulosic feedstocks via fast pyrolysis. It is a complex mixture comprised of hundreds of highly oxygenated organic compounds originating from lignin and carbohydrates and is recognized as a clean renewable bio-fuel, an attractive alternative to fossil fuels. It can be easily transported and used directly in boilers and modified turbines or upgraded/fractionated for drop in fuels or chemical production. Proper bio-oil characterization is important in optimizing the pyrolysis process, bio-oil upgrading and utilization, and its stabilization for long-term storage. With this in mind, research has been undertaken to develop better techniques to rapidly profile the composition of whole bio-oil samples, and an accelerated aging study performed to determine why bio-oil is unstable upon storage. Pyrolysis-GC/MS and TLC-FID were used as tools to differentiate bio-oils of different lignocellulosic biomasses, and among thermal-cracking (upgrading) fractions. Results showed that birch bio-oil had high syringol derivatives compared to pine and barley straw bio-oils which had higher guaiacol and non-methoxy-phenolic compounds, respectively, compared with birch bio-oil. TLC-FID was successful in bio-oil differentiation, showing diagnostic chromatographic profile differences. Direct infusion-ESI-ion trap MS and ESI-ion trap MS 2 were successfully used in the analysis of forest-residue bio-oil and reference bio-oils from cellulose and hardwood lignin dissolved in methanol:water. NH4Cl can be used as a dopant to distinguish carbohydrate-derived products from other bio-oil components. NaOH and NaCl dopants resulted in the highest intensity peaks in negative ion mode and positive mode, respectively. Tandem MS, that is, ESI-Ion Trap MS 2 was a successful tool for the confirmation of iii individual target ions such as levoglucosan and cellobiosan and for structural insight into lignin products. In accelerated aging (at 80 °C for 1, 3 and 7 days) studies, the physical and chemical properties of bio-oil from ash wood (produced from a pilot-scale auger pyrolyzer) and birch wood (lab-scale pyrolyzer) were monitored in order to identify the factors responsible for bio-oil instability. Water content, viscosity, and decomposition temperature (by TGA) increased for both bio-oil samples with aging. Chemical analysis showed reduction in amount of most of the bio-oil components as aging progressed, typically for are olefins and aldehydes. The oils remained a single phase throughout until the 7th day. viii 2.4. Conclusion 65 2.5. References 66 Chapter 3: Direct infusion mass spectrometric analysis of bio-oil using ESI-Ion Trap MS 69
Catalytic upgrading of biomass-derived oils to transportation fuels and chemicals
The Canadian Journal of Chemical Engineering, 1991
This paper provides a review of the catalytic upgrading of biomass-derived oils such as wood pyrolytic oils, plantivegetable oils and tall oil to transportation fuels and useful chemicals. Both zeolite and hydrotreating type catalysts have been found suitable for upgrading which was usually done in fixed bed reactors. The hydrotreatment of pyrolytic oils at 250-450°C and 15-20 MPa H, pressures has been reported to yield up to 55 wt. % of liquid product containing 40-50 wt. % of gasoline range hydrocarbons. In the case of HZSM-5, the upgrading has been carried out at atmospheric pressure and 350-500°C and over 85 wt. % conversions of plant oils and tall oil have been achieved under optimum conditions. Liquid product yields from these oils were up to 70 wt. % of feed which contained 40-50 wt. % aromatic hydrocarbons. With the high pressure pyrolytic oil, pitch conversions of over 75 wt. % have been observed with HZSM-5 using co-feeds such as tetralin. However, there is only scant information available on the kinetic and mechanistic aspects of upgrading of these oils.
Recent research progress on bio-oil conversion into bio-fuels and raw chemicals: a review
Journal of Chemical Technology & Biotechnology, 2018
Recent advances in lignocellulosic biomass valorization for producing fuels and commodities (olefins and BTX aromatics) are gathered in this paper, with a focus on the conversion of bio-oil (produced by fast pyrolysis of biomass). The main valorization routes are: i) conditioning of bio-oil (by esterification, aldol condensation, ketonization, in situ cracking, and mild hydrodeoxygenation) for its use as a fuel or stable raw material for further catalytic processing; ii) production of fuels by deep hydrodeoxygenation; iii) ex situ catalytic cracking (in line) of the volatiles produced in biomass pyrolysis, aimed at the selective production of olefins and aromatics; iv) cracking of raw bio-oil in units designed with specific objectives concerning selectivity, and; v) processing in fluidized bed catalytic cracking (FCC) units. This review deals with the technological evolution of these routes, in terms of catalysts, reaction conditions, reactors, and product yields. A study has been carried out on the current state-of-knowledge of the technological capacity, advantages and disadvantages of the different routes, as well as on the prospects for the implementation of each route within the scope of the Sustainable Refinery.