19 research outputs found

    Bio-oil Stabilization by Hydrogenation over Reduced Metal Catalysts at Low Temperatures

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    The thermal and chemical instability of biomass fast pyrolysis oil (bio-oil) presents significant problems when it is being converted to hydrocarbon transportation fuels. Development of effective approaches for stabilizing bio-oils is critical to the success of the biomass fast pyrolysis and bio-oil upgrading technology. Catalytic hydrogenation to remove reactive species in bio-oil has been considered as one of the most efficient ways to stabilize bio-oil. This paper provides a fundamental understanding of hydrogenation of actual bio-oils over a Ru/TiO<sub>2</sub> catalyst under conditions relevant to practical bio-oil hydrotreating processes. The results indicated hydrogenation of various components of the bio-oil, including sugars, aldehydes, ketones, alkenes, aromatics, and carboxylic acids, over the Ru/TiO<sub>2</sub> catalyst and 120 to 160 °C. Hydrogenation of these species significantly changed the chemical and physical properties of the bio-oil and overall improved its thermal stability, especially by reducing the carbonyl content, which represented the content of the most reactive species (i.e., sugar, aldehydes, and ketones). The change of content of each component in response to increasing hydrogen additions suggests the following bio-oil hydrogenation reaction sequence: sugar conversion to sugar alcohols, followed by ketone and aldehyde conversion to alcohols, followed by alkene and aromatic hydrogenation, and then followed by carboxylic acid hydrogenation to alcohols. Sulfur poisoning of the reduced Ru metal catalysts was significant during hydrogenation; however, the inorganics at low concentrations had minimal impact at short times on stream, indicating that sulfur poisoning was the primary deactivation mode for the bio-oil hydrogenation catalyst. The knowledge gained during this work will allow rational design of more effective catalysts and processes for stabilizing and upgrading bio-oils

    Final Project Report Project 10749-4.2.2.1 2007-2009

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    This is the final report for the DOE Project 10749-4.2.2.1 for the FY2007 - FY2009 period. This report is non-proprietary, and will be submitted to DOE as a final project report. The report covers activities under the DOE Project inside CRADA 269 (Project 53231) as well as project activites outside of that CRADA (Project 56662). This is the final report that is summarized from the non-proprietary quarterlies submitted to DOE over the past 2.5 years, which in turn are summaries from the proprietary technical reporting to UOP

    Molybdenum Carbides, Active and <i>In Situ</i> Regenerable Catalysts in Hydroprocessing of Fast Pyrolysis Bio-Oil

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    This paper describes properties of molybdenum carbides as a potential catalyst for fast pyrolysis bio-oil hydroprocessing. Currently, high catalyst cost, short catalyst lifetime, and lack of effective regeneration methods are hampering the development of this otherwise attractive renewable hydrocarbon technology. A series of metal-doped bulk Mo carbides were synthesized, characterized, and evaluated in sequential low-temperature stabilization and high-temperature deoxygenation of a pine-derived bio-oil. During a typical 60 h run, Mo carbides were capable of upgrading raw bio-oil to a level suitable for direct insertion into the current hydrocarbon infrastructure with residual oxygen content and total acid number of upgraded oils below 2 wt % and 0.01 mg KOH g<sup>–1</sup>, respectively. The performance was shown to be sensitive to the type of metal dopant, Ni-doped Mo carbides outperforming Co-, Cu-, or Ca-doped counterparts; a higher Ni loading led to a superior catalytic performance. No bulk oxidation or other significant structural changes were observed. Besides the structural robustness, another attractive property of Mo carbides was <i>in situ</i> regenerability. The effectiveness of regeneration was demonstrated by successfully carrying out four consecutive 60 h runs with a reductive decoking between two adjacent runs. These results strongly suggest that Mo carbides are a good catalyst candidate which could lead to a significant cost reduction in hydroprocessing bio-oils. We highlight areas for future research which will be needed to further understand carbide structure–function relationships and help design practical bio-oil upgrading catalysts based on Mo carbides

    Sulfur-Tolerant Molybdenum Carbide Catalysts Enabling Low-Temperature Stabilization of Fast Pyrolysis Bio-oil

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    Low-temperature hydrogenation of carbonyl compounds can greatly improve the thermal stability of fast pyrolysis bio-oil, thereby enabling long-term operation of upgrading reactors which generally require high temperatures to achieve deep deoxygenation. The state-of-the-art hydrogenation catalysts, precious metals such as ruthenium, although effective in carbonyl hydrogenation, deactivate due to high sulfur sensitivity. In the present work, we showed that molybdenum carbides were active and sulfur-tolerant in low-temperature conversion of carbonyl compounds. Furthermore, due to surface bifunctionality (i.e., both metallic and acid sites present), carbides catalyzed both CO bond hydrogenation and C–C coupling reactions. Combined, these reactions transformed carbonyl compounds to more stable and higher molecular weight oligomeric compounds while consuming less hydrogen than pure hydrogenation. The carbides proved to be resistant to other deactivation mechanisms including hydrothermal aging, oxidation, coking, and leaching. These properties enabled carbides to achieve and maintain good catalytic performance in both aqueous-phase furfural conversion and real bio-oil stabilization in the presence of sulfur. This finding strongly suggests that molybdenum carbides can provide a catalyst solution necessary for the development of practical bio-oil stabilization technology
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