349445 Blueprint of an Integrated Biorefinery: Production of Biobutanol and 1,3-Propanediol from Waste and Renewable Biomass

Monday, November 4, 2013
Grand Ballroom B (Hilton)
William T. Hale1, Baishali Kanjilal2, Iman Noshadi1, Nicholas Intoci1, Brittany Bendel1 and Richard Parnas1,2, (1)Chemical and Biomolecular Engineering, University of Connecticut, Storrs, CT, (2)Institute of Materials Science, University of Connecticut, Storrs, CT

The transition to a sustainable and energy secure future is a current fundamental challenge greater than any in modern history.  Driven as much by the threat of high costs from dwindling energy supplies as by environmental concern, sustainability and green technology has become a major phenomenon in recent years.  The global dependence on conventional fossil fuels and other petroleum based chemicals and its ramifications on climate change and the economy makes the diversification of the global energy profile to renewables appealing.

Replacing petroleum derived fuels and chemical sources with an emphasis on renewable fuels and chemicals is an imperative policy tool for the future.  Biomass feedstock based fuels and chemicals offer advantages of easy production, excellent renewability, environmental friendliness and possible use in a wide variety of applications with its existing infrastructure.  The goals and aspirations of our research group center around the idea of an integrated renewable fuels and chemicals biorefinery.  This includes the integration of processes which adopt novel extraction and fermentation pathways for the production of fuels and intermediate platform biorenewable chemicals.  The integrated processes above maximize the value derived products and intermediates from the biomass feedstocks.  This is a benefit that not only addresses the environmental and disposal concerns for the waste based feedstock, but also underscores the enormous positive effects it has on the overall process economics.

Our first study focuses on the breakdown of various plant-like materials to extract key components from the matter to be used in the production of renewable fuels and chemicals.  In previous work a unique method of cultivation for seaweed was developed to efficiently grow seaweeds with varying contents of lipid and sugar compositions.  Based off of this, we developed an innovative method of extraction of sugars and lipids from seaweed using a switchable polarity hydrophobic ionic liquid.  The ionic liquid breaks down the cell walls of the seaweed and releases the lipids into ionic liquid layer, while the sugars remain behind in the aqueous layer.  The presence of the lipids in the ionic liquid layer is confirmed by GC traces.  The lipid can be obtained by carbon dioxide bubbling which switches the polarity of the ionic liquid.  This way the ionic liquid can be recovered and recycled into the system.  The ionic liquid, while breaking down the cell walls, does not hydrolyze the long chain sugars.  The hydrolysis of these sugars is carried out using sulfuric acid after layer separation.  The HPLC traces of the released sugars before and after hydrolysis confirm this phenomenon and are utilized to compute the extent of extraction.

Butanol is a possible direct replacement in the transportation sector for gasoline.  It proffers advantages over the currently used ethanol because of its higher energy density and lower hydrophilic character reducing damage to car parts via rusting.  Studies on butanol production from glucose using Clostridium Acetobutylicum have been carried out earlier.  However, this strain, despite being the best butanol producer, fails to grow under non ideal conditions using the hydrolyzed sugars from natural sources.  Our study utilized the sugars obtained after acid catalyzed hydrolysis from seaweed to successfully convert them to butanol using Clostridium Saccharoperbutylacetonicum.  The utilization of sugar and production of butanol was confirmed by HPLC.

Lipids from various sources of biomass such as seaweed, waste cooking oil (yellow grease), animal fats and brown grease can be converted to biodiesel via esterification and transesterification processes.  Glycerol is a byproduct of these processes.  As a result of being the waste basket for the processes aforementioned, this glycerol is contaminated with chemicals like methanol, potassium hydroxide, and potassium phosphate.  This glycerol has little fiscal value even after purification.  Hence, its conversion to a more valuable intermediate biorenewable chemical such as 1,3-propanediol can serve as a recourse to its utilization while adding value to the process of biodiesel production.  Clostridium Butyricum is the most commonly used bacterial strain for glycerol fermentation to 1,3-propanediol and it has been studied extensively for pure glycerol feed stocks.  In our study soil based inoculum was grown in selective medium and used to ferment waste glycerol to 1,3-propanediol.  A study was also done to analyze the effects that excess acetate and butyrate has on the fermentative production of 1,3-propanediol and the results were compared to the fermentative production from pure glycerol using C. Butyricum.  These results were taken up for an acetate-butyrate CSTR cycle in hopes to optimize the production of 1,3-propanediol.

Biorefineries are a window to the future of sustainability and shall play a vital role in reducing dependence on petroleum based fuels and chemicals along with essential ramifications on the global climate.

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