(3ak) Deoxygenation and Fundamental Catalysis for Sustainable Energy Applications

The General Theme of my research is Catalysis for Sustainable Energy. I received my PhD in chemical Engineering from Mississippi State University in December 2010. I am presently working as a Postdoctoral Research Associate at the Washington State University. My PhD project dealt with converting oxygenates derived from syngas to hydrocarbon. The particular oxygenates under consideration were acetic acid, acetone, methyl acetate, ethanol and acetaldehyde. Deoxygenation was performed using titania based catalytic systems. Most of my PhD research was applied catalysis in nature. However, in my postdoc work I am concentrating on fundamental catalysis to give myself a well-rounded catalysis experience. I am studying and analyzing Pt-Re bimetallic catalysts used for aqueous phase reforming of biomass. The influence of Rhenium is being investigated to understand the catalyst functioning. Several characterization techniques are being employed such as DRIFTS, TPRS, PXRD, XPS and TGA. Since this is a ‘work in progress’, I shall not be able to give more details at present. However, if you need any specific details, you can contact me using the information at the end of the abstract. Also, I have a Master of Science degree in Chemical Engineering from Mississippi State University. My MS research was concerned with Dielectrophoresis of Erythrocytes. Since this is not relevant to my future research, I am not providing details. However, I have a publication from that research.

Doctor of Philosophy (Ph.D.) Research:

Background

My PhD Project concerns with converting short chain organic oxygenates to fuel range hydrocarbon. This project was part of a campus wide effort to develop sustainable energy at Mississippi State University. Under this program a collaborative research group was established called Sustainable Energy Research Center (SERC), www.serc.msstate.edu, comprising of researchers in the departments of Chemical Engineering, Forest Products, Chemistry, Agricultural and Biological Engineering to name a few. As part of this endeavor, our group under my advisor, Prof. Mark White was developing non-Fisher Tropsch technology for biomass derived syngas to be converted to gasoline. One approach to achieve this goal is to first convert syngas to alcohols and then convert alcohols to gasoline. This approach while effective, yields oxygenate by-products. My Project was to study the use of Titanium dioxide, TiO₂ (titania), as a catalyst to convert these byproducts to fuel range hydrocarbon to increase the viability of the biomass-to-gasoline technology.

Accomplishments

The main oxygenate by-products formed during conversion of syngas to alcohols are acetic acid, acetaldehyde, methyl acetate and acetone. Hence initially, I performed batch reactor studies using both acid catalysts like H+/ZSM-5 and silica alumina, and base catalysts like titania and magnesium oxide. It was concluded that base catalysts yield almost no coke when reacted with these oxygenates. Then I studied interactions between these oxygenates by reacting pairs of these compounds on titania in a batch reactor. The results were documented and showed no prohibitive interactions. The data from these experiments will be submitted to the journal, Biomass and Bioenergy.

Acetic acid has been shown in literature as one of the most coke-causing compounds in both syngas derived products as well as in bio-mass pyrolysis products when tried to convert to hydrocarbon. Hence titania as a catalyst has all the more significance as it can convert acetic acid to acetone and subsequently acetone to mesitylene. I decided to study the acetone condensation to mesitylene much more closely as it forms an important link in converting acetic acid to hydrocarbon. Also, Acetone itself can be converted to liquid hydrocarbon. I studied this reaction in high pressure conditions similar to those employed in syngas conversion to alcohols. This was done keeping in mind the possibility of using a single bed to convert syngas to gasoline including all by-products. I had excellent success in this endeavor and reported high yield and selectivity of mesitylene from acetone. I have also made some mechanistic studies which underline the importance of the dual acid-base nature of titania to catalyze this reaction. The data was presented in national meetings and I have submitted a paper to the journal, Applied Catalysis A: General.

As alcohols can be easily converted to gasoline range hydrocarbon on zeolite catalyst, I wanted to show that alcohols were essentially inert on titania. This would ensure that only by-products are converted to hydrocarbon on titania and alcohols are retained as such. In course of making this study, when ethanol was reacted on titania, I found that tiny amounts of 1-butanol was found. I immediately saw an opportunity to upgrade alcohols in carbon number. This would make them better fuel additives than ethanol. Also, previous research in our lab showed that higher alcohols can give better yields of gasoline when reacted on zeolites than methanol or ethanol. Hence I decided to pursue making 1-butanol from ethanol as well. Pacific Northwest National Laboratories (PNNL) has been working on direct conversion of syngas to higher alcohols but was successful only to make ethanol and not substantial yields of any higher ones. Hence our group collaborated with PNNL and I travelled to Richland, WA to work as an intern at PNNL for 10 weeks to show that titania can be used to convert ethanol to 1-butanol. I was successful in doing so. Also, my interaction with scientists at PNNL was a rich experience for me. After returning to Mississippi State University, I continued to work on converting ethanol to 1-butanol not only on titania but also on catalysts with similar known surface chemistry. I found that Zirconium dioxide (Zirconia) could convert ethanol to 1-butanol with much better yields than titania. Also, while titania made 1-butanol as the highest alcohol from ethanol, zirconia could convert ethanol to not only 1-butanol but also various pentanols, hexanols and even octanol. Mechanistic studies revealed that alcohols higher then 1-butanol do not self condense on zirconia. Instead, ethanol reaction with intermediate alcohols such as 1-propanol or 1-butanol or hydration of oligomerized olefins could yield higher alcohols. Also, it was known that only primary alcohols are reactive on this metal oxide. The results of this work are submitted as a paper to the journal, Journal of Molecular Catalysis A:Chemical.

From the work that I performed for the last 36 months, I gave 5 presentations, received 1 provisional patent and was selected for 1 award. I produced 2 research papers as corresponding author which are currently in review. One more paper will be submitted shortly. I am also presently drafting a review paper on the general theme of deoxygenation catalysis for sustainable energy as a co author with my advisor, Prof. Mark White. This is an invited paper from the editors of the book series, Advances in Catalysis. I gave a brief overview of my accomplishments during my Ph.D. I shall be excited to present these in great detail if invited to your campus.

Contact Information:

Prashant Daggolu, PhD

Postdoctoral research Associate

Washington State University

305 NE Spokane Street, Dana 118

Pullman, WA – 99164

Phone: 662 518 1100

Fax: 509 335 4806

Email: prashant.daggolu@wsu.edu