An Alternative Biofuel: LPG from Biomass- Derived Organic Acids TIE Graduate Research Fellowship Report

Size: px

Start display at page:

Download "An Alternative Biofuel: LPG from Biomass- Derived Organic Acids TIE Graduate Research Fellowship Report"

Whitney Dickerson
5 years ago
Views:

1 An Alternative Biofuel: LPG from Biomass- Derived Organic Acids TIE Graduate Research Fellowship Report Branko Zugic Department of Chemical and Biological Engineering Tufts University, Medford MA Supervised by: Maria Flytzani- Stephanopoulos (Advisor) Department of Chemical and Biological Engineering Tufts University, Medford MA May 2011

2 Project Background and Objectives The current economic, political, and energy policy climates around the world have been the motivation for the development of numerous approaches to the renewable, clean energy challenge. Many of these techniques such as biomass gasification, aqueous- phase reforming, and fermentation are focused on producing next generation fuels (i.e. hydrogen, ethanol) 2. These fuels are characterized by fundamentally efficient usability although their full potential will not be realized until the difficulties associated with their production and distribution are addressed. Alternatively, liquefied petroleum gas (LPG; a mixture of propane and butane) is currently used across many industries in both rural and urban applications worldwide. LPG, however, is derived primarily from crude oil refining and extraction from natural gas reservoirs. Its price, availability, and carbon footprint are, as a result, directly related to those of oil and natural gas. This project was aimed at addressing these challenges by investigating a novel system that combines biological processing of biomass (fermentation) and the catalytic conversion of the products to LPG- like fuels. The process is shown in Figure 1. The goal of this work was to understand the nature of supported platinum- and palladium- based catalysts and their performance (i.e. activity, selectivity, and stability) for the decarboxylation and hydrogenation of short aliphatic carboxylic acids, such as butyric acid, to C3 and C4 alkane fuels under mild temperatures and pressures. This process refers to the right hand reactor shown in Figure 1, after the fermentation of biomass and extraction of the useful products. The main objectives of this work were to (i) elucidate and control the nature of the interaction of active metal clusters (i.e. Co, Pd, Pt) with carbon and metal oxide supports with a large number of defects Figure 1. Schematic of an envisioned process for the production of LPG by a fermentor/catalytic reactor system. Adapted from Wu and Yang 1 and/or binding sites (for anchoring, stabilizing, and dispersing metals) and (ii) conduct a systematic study of the activity and selectivity of carbon- and metal oxide- supported Pd, Co, and Pt catalysts for the production of C3 and C4 hydrocarbons through the decarboxylation and hydrogenation of butyric acid.

Materials and Methods The catalysts tested in this work were prepared in the Nano Catalysis and Energy Laboratory (NanoCEL) at Tufts University.

3 Materials and Methods The catalysts tested in this work were prepared in the Nano Catalysis and Energy Laboratory (NanoCEL) at Tufts University. Raw materials were purchased from Cheap Tubes Inc, Alfa Aesar, Sigma Aldrich, and other suppliers. These materials were used in the synthesis of various palladium- based catalysts supported on modified carbon nanotubes. Briefly, the as- received multi- walled carbon nanotubes (MWNTs) were treated in nitric acid in order to introduce surface oxygen groups, such as carboxyls, lactones, quinones, etc. Following a through washing of these surfaces, ion exchange of some of the groups with various alkali metals was performed in a similar manner to the acid reflux. Palladium (and other promoters such as platinum, cobalt and rhenium) were then deposited onto all of these surfaces. The resulting catalysts were characterized using various techniques, such as transmission electron microscopy (at Harvard s CNS and MIT s CMSE facilities) as well as x- ray absorption spectroscopy (at MIT s CMSE) and other x- ray absorption techniques (at Brookhaven National Laboratory). Their performance was tested in a high- pressure reactor system built in the NanoCEL laboratory at Tufts and operating at 225 C and 440 psi with a feed of aqueous butyric acid solutions. Results The prepared materials were all of similar final structure, as shown in Figure 2. The catalysts consist of functionalized multi- walled nanotubes (represented by the light, hollow structures in the transmission electron micrograph) decorated with metal nanoparticles (represented by black dots). The typical particle size obtained for palladium catalysts was on the order of 1 3 nm, depending on the extent of acid modification of the MWNTs. Through x- ray absorption spectroscopy, we were able to determine the oxidation state of the metals on the surface. Results indicate a mixture of forms on the surface, likely due to the ease of oxidation of that small particles as well as the interaction of the metal with the surface oxygen groups of the support (MWNT). Following the state of the catalysts in- situ through the course of the reaction Figure 2. 1 wt% Pt on acid- proved to be difficult, although there is some modified MWNT after reaction indication of reduction of the metal phase to the (water- gas shift reaction) zero- valent state. The performance of palladium- based catalysts for the decarboxylation of butyric acid was evaluated relative to that of commercial carbon- supported palladium

4 materials. Contrary to studies that show size- selective deactivation 3, it was found that altering the particle size through various degrees of surface modification was not effective in mitigating the deactivation of the materials due to coke deposition on the surface of the metal particles (i.e. active sites). While the materials could be regenerated by oxidation of the surface (burning off the deposits), deactivation followed a similar trend to the commercial material. Modification of the MWNT with sodium before addition of the metal showed some promise. By adding alkali metals, such as sodium, we were able to alter the acidity of the surface groups. This modification led to the decrease in cracking propensity to smaller hydrocarbons when using platinum as the active metal. This led to a higher yield of propane compared to that obtained with platinum catalysts supported on commercial platinum and oxidized MWNTs. Conclusions The decarboxylation reaction is one of the holy grails of catalysis. Catalysts suffer greatly from rapid deactivation and low activities under decarboxylation conditions Our approach does not seem to have overcome these challenges as of yet, although the use of alkali metal modifications has shown promise. The application of these materials to other ongoing studies has, in particular, yielded interesting results. The materials have now been tested for hydrogen production reactions (i.e. water- gas shift reaction) and have shown that the modification of the MWNT supports with alkali metals result in a drastic increase in activity. These results are currently being investigated in more depth. We will continue to try to understand the needs, at a fundamental level, for the decarboxylation in the hopes of developing more active and stable materials. We believe that with further development, this project can contribute valuable information to the field and potentially provide a renewable source of green energy. References 1. Z.T. Wu, S.T. Yang, Extractive fermentation for butyric acid production from glucose by Clostridium tyrobutyricum, Biotechnology and Bioengineering 82, (2003) 2. G.W. Huber, S. Iborra, A. Corma, Synthesis of transportation fuels from biomass: Chemistry, catalysts, and engineering, Chemical Reviews 106, (2006) 3. M. Besson, P. Gallezot, Selective oxidation of alcohols and aldehydes on metal catalysts, Catalysis Today 57, (2000) 4. M.L. Toebes, Y. Zhang, J. Hijek, T. Alexander Nijhuis, J.H. Bitter, et al, Support effects in the hydrogenation of cinnamaldehyde over carbon nanofiber- supported platinum catalysts: characterization and catalysis, Journal of Catalysis 226, (2004) 5. I. Kubickova, M. Snare, K. Eranen, P. Maki- Arvela, D.Y. Murzin, Hydrocarbons for diesel fuel via decarboxylation of vegetable oils, Catalysis Today 106, (2005)

5 6. P. Maki- Arvela, I. Kubickova, M. Snare, K. Eranen, D.Y. Murzin, Catalytic deoxygenation of fatty acids and their derivatives, Energy & Fuels 21, (2006) 7. M. Snare, I. Kubickova, P. Maki- Arvela, K. Eranen, D.Y. Murzin, Heterogeneous catalytic deoxygenation of stearic acid for production of biodiesel, Industrial & Engineering Chemistry Research 45, (2006) 8. P. Maki- Arvela, M. Snare, K. Eranen, J. Myllyoja, D.Y. Murzin, Continuous decarboxylation of lauric acid over Pd/C catalyst, Fuel 87, (2008) 9. M. Snare, I. Kubickova, P. Maki- Arvela, D. Chichova, K. Eranen, D.Y. Murzin, Catalytic deoxygenation of unsaturated renewable feedstocks for production of diesel fuel hydrocarbons, Fuel 87, (2008) 10. S. Lestari, P. Maki- Arvela, H. Bernas, O. Simakova, R. Sjoaholm, et al, Catalytic deoxygenation of stearic acid in a continuous reactor over a mesoporous carbon- supported Pd catalyst, Energy & Fuels 23, (2009) 11. I. Simakova, O. Simakova, P. Maki- Arvela, A. Simakov, M. Estrada, D.Y. Murzin, Deoxygenation of palmitic and stearic acid over supported Pd catalysts: Effect of metal dispersion, Applied Catalysis A: General 355, (2009) 12. H. Bernas, K. Eranen, I. Simakova, A.R. Leino, K. Kordas, et al, Deoxygenation of dodecanoic acid under inert atmosphere, Fuel 89, (2010) 13. I. Simakova, O. Simakova, P. Maki- Arvela, D.Y. Murzin, Decarboxylation of fatty acids over Pd supported on mesoporous carbon, Catalysis Today 150, (2010)

6 Budget Monies were spent according to the proposed budget with some re- allocations due to unexpected travel costs to Brookhaven National Laboratory for synchrotron facility use. Reduction in the amount spent on characterization at MIT s CMSE facility was made accordingly. Name Branko Zugic Proposal Title An Alternative Biofuel: LPG from Biomass-Derived Organic Acids PROJECT BUDGET Supplies Description Cost Materials (Gases, Reagents) $950 Supplies Total $ Stipend Description Cost Student Stipend (Branko Zugic) $3, Stipend Total $3, Travel Description Cost Brookhaven National Lab Synchrotron Travel $ Travel Total $ Other Description Cost MIT CMSE Facility Use $1, Other Total $0.00 TOTAL $5,950.00

have also been successfully tested in low temperature NH 3 Noble metals, especially platinum, have been reported to be active catalysts in NH 3

have also been successfully tested in low temperature NH 3 Noble metals, especially platinum, have been reported to be active catalysts in NH 3 46 Novel Pt/CNT and Pd/CNT catalysts for the low temperature ammonia and ethanol assisted selective catalytic reduction of NO Anna Avila 1 *, Mari Pietikäinen 1, Mika Huuhtanen 1, Anne-Riikka Leino 2,