Grantee Research Project Results
Final Report: Synthetic Gasoline From Biomass
EPA Contract Number: EPD07028Title: Synthetic Gasoline From Biomass
Investigators: Fraenkel, Dan
Small Business: Eltron Research & Development Inc.
EPA Contact: Richards, April
Phase: I
Project Period: March 1, 2007 through August 31, 2007 (Extended to October 10, 2007)
Project Amount: $70,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2007) RFA Text | Recipients Lists
Research Category: SBIR - Emission Reductions and Biofuels , Small Business Innovation Research (SBIR)
Description:
The combination of soaring oil prices and the continuing global warming caused by greenhouse gas emission, especially CO2 emission from fossil fuel burning, is creating a strong impetus to develop and implement an energy economy based on our plentiful renewable sources in the United States. Renewable energy sources undoubtedly offer considerable environmental benefits. Ideally, a gasoline-like biofuel should be developed that could be produced effectively and economically from biomass, either directly or indirectly, that will be cleaner burning and less polluting than petroleum-derived gasoline. One may envision a synthetic hydrocarbon mixture in the gasoline boiling range that comprises the best components of gasoline from the standpoint of a fuel performance, and lacks the undesirable components such as straight-chain alkanes and aromatics as well as contaminants such as metals, particulates, and S and N compounds.
This project was aimed at developing such a synthetic gasoline (SG) from biomass. Biomass-derived methanol could be converted in one step to a hydrocarbon mixture rich in isoalkanes. Eltron Research, Inc. further assumed that a methanol-to-SG process could be economical even if methanol is produced from biomass. In this project, Eltron Research evaluated whether such a process could be technologically feasible and commercially viable.
The core of this project is a catalytic reaction in which a strong solid acid such as sulfated zirconia (SZ, ‘ZrO2/SO4-’) catalyzes complete conversion of methanol under relatively mild conditions selectively to a hydrocarbon mixture very rich in C4 – C9 isoalkanes. This process can be referred to as methanol-to-isoalkanes, or MTI. The parallel conversion of methanol-to-gasoline over MFI zeolite (HZSM‑5), known as Mobil’s MTG Process, produces a hydrocarbon mixture rich in unsaturates, including the environmentally undesired aromatics, and involves rejection of C4-alkanes with a substantial loss of gasoline yield.
Within Phase I of this project, Eltron Research planned to build a suitable lab-scale microreactor for fixed-bed catalytic conversion of methanol; prepare, analyze, and characterize standard and advanced SZ and SZ-based catalytic systems; and compare their properties and catalytic behavior in methanol conversion to that of a standard HZSM-5. In addition, at least one more zeolite in its strongly acidic form as an alternative MTI catalyst was to be studied. Blends of components of typical reaction mixtures were to be made and analyzed for their properties as potential gasoline fuel to simulate the SG produced by the MTI reaction.
Summary/Accomplishments (Outputs/Outcomes):
Within this Phase I, the planned microreactor was designed and built, and methods of operation were developed as well as product analysis. Many samples of ZSM-5, SZ, and an additional high-silica zeolite other than ZSM-5 were synthesized; these preparations were characterized and compared by various chemical and spectroscopic methods. A few of the most promising systems were tested as catalysts in methanol conversion. Eltron Research successfully reproduced the preliminary work that reported methanol conversion to primarily isoalkanes over SZ as mentioned and discussed in the Phase I proposal. Advanced systems based on SZ and zeolites were successfully prepared, which could be more suitable for the MTI reaction because they are less prone to catalyst deactivation under the reaction conditions employed. Higher space velocity (WHSV >1) in the case of SZ resulted unexpectedly in the production of some aromatics in addition to the main product mixture of isoalkanes. This is at odds with the results of the old preliminary study; however, that study was not done at high WHSV. The aromatics found in the reaction over SZ were at low concentration, though at 3-4 times less than those typically obtained in the case of ZSM-5; also, they did not appear to contain benzene.
Because the stoichiometry of the MTI reaction requires formation of oxidized methanol byproduct that could contribute to catalyst deactivation, it is anticipated that the catalysis could be more effective if performed in the presence of dihydrogen gas using a bifunctional catalyst combining strong acidity and hydrogenation activity. Several catalyst candidates for this CH3OH + H2 reaction were prepared and will be tested shortly. MTI typically produces 10-20 percent ethylene as byproduct that could be used for polyethylene if not incorporated into the SG (as ethanol, ETBE, or alkylate). The major product of the process—isobutane—will be used primarily in a subsequent alkylation reaction to produce isooctane and/or isononane (with the co-produced isopentane).
The part of the work related to the SG blends, based on this concept and on the analysis of product mixtures obtained in the current Phase I laboratory work, was accomplished only partially. This is because of a delay in catalyst testing, which was caused by a delay in reactor construction and by problems associated with catalyst preparation. However, one initial small blend (100 ml) has been prepared, and its gas chromatographic analysis closely resembles that of a typical methanol conversion mixture, with the isobutane entirely transformed into isooctane. A computer simulation analysis was performed with two typical SG mixtures based on Eltron Research’s current catalytic data. This analysis confirms that if developed, the MTI process could indeed produce SG of very high quality. For example, the above-mentioned SG compositions (blends) yielded the following results: Octane—RON = 97; RVP—2–6 psi; API gravity—70–77; molecular weight—100–115, 10 percent volume boiling point—80–200°F, 90 percent volume boiling point—210–260°F, heat of combustion (net)—approximately 110,000 Btu/gal. The results are comparable with those of typical gasoline with the octane and API gravity being higher and the RVP being lower. SG, therefore, is a fuel that combusts more efficiently and completely and produces less pollution than standard gasoline.
Conclusions:
There appears to be ample interest in the potential commercialization of processes for alternate fuels based on biomass, especially fuels that could be close in structure and properties to gasoline, yet are cleaner and less polluting. The current MTI process offers such an option. After a start-up period for this project that resulted in the confirmation of most of the findings of the preliminary work, Eltron Research now is able to further develop this process. Future efforts should be focused on improvement of the reaction conditions and product analysis and on the design of better catalysts, which will be more efficient and stable.
Several strategies were developed to achieve these goals. In parallel, more simulated SG blends should be prepared and undergo computer simulation, and they should be analyzed in a suitable fuel testing laboratory. During Phase II of this project, further progress in the research and development effort, including the construction and operation of a bench-scale MTI reactor, is planned. Eltron Research also hopes to attract industrial interest, possibly of an oil company, for mutual cooperation on further developing the program beyond Phase II. MTI from biomass-derived methanol could be a multibillion dollar business. If methanol initially is produced from natural gas or coal, Eltron Research expects that in 3-5 years after Phase II, MTI production could run on a scale similar to that of a small Fischer-Tropsch plant. For example, a single commercial plant making 10,000 barrels/day of SG would have annual sales worth approximately $12 billion.
Supplemental Keywords:
small business, SBIR, synthetic gasoline, methanol synthesis, methanol-to-gasoline, acid catalyst, zeolite, zirconia, alkylation, isoalkane,, RFA, Scientific Discipline, TREATMENT/CONTROL, Sustainable Industry/Business, Environmental Chemistry, Sustainable Environment, Technology, Technology for Sustainable Environment, Environmental Engineering, renewable feedstocks, clean technologies, environmentally friendly transportation fuel, methanol, biomass, alternative fuel, biodiesel fuel, energy technology, biofuel, emission reductionThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.