Grantee Research Project Results
2005 Progress Report: A Novel Approach to Ultra-Deep Desulfurization of Transportation Fuels by Sulfur-Selective Adsorption for Pollution Prevention at the Source
EPA Grant Number: R831471Title: A Novel Approach to Ultra-Deep Desulfurization of Transportation Fuels by Sulfur-Selective Adsorption for Pollution Prevention at the Source
Investigators: Song, Chunshan , Kim, Jae Hyung , Clemons, Jennifer L , Zhou, Anning , Ma, Xiaoliang
Current Investigators: Song, Chunshan , Kim, Jae Hyung , Clemons, Jennifer L , Zhou, Anning , Yoosuk, Boonyawan , Sundararaman, Ramanathan , Subramani, Velu , Ma, Xiaoliang , Wang, Xiaoxing
Institution: Pennsylvania State University
EPA Project Officer: Aja, Hayley
Project Period: October 15, 2003 through October 14, 2006 (Extended to August 31, 2007)
Project Period Covered by this Report: December 12, 2004 through December 11,2005
Project Amount: $325,000
RFA: Technology for a Sustainable Environment (2003) RFA Text | Recipients Lists
Research Category: Sustainable and Healthy Communities , Pollution Prevention/Sustainable Development
Objective:
The overall objectives of this research project are to: (1) design new adsorbents with high selectivity for removing sulfur compounds from transportation fuels under ambient temperature and pressure; (2) develop new and advanced catalysts for the hydrodesulfurization (HDS) of concentrated sulfur fractions; and (3) understand the fundamentals of adsorption-desorption and catalytic HDS processes by a combination of experimental and computational analyses. The specific objectives of this project for the present period are to evaluate the adsorption performance of the typical adsorbents, including nickel-based adsorbent, activated alumina, and activated carbon and to get a better fundamental understanding of the adsorptive mechanism and selectivity of the various compounds on the different adsorbents by a combination of the experimental results and computational results.
Approach:
The transportation fuels, particularly gasoline, diesel and jet fuel, contain organo sulfur compounds, mainly thiophene and its derivatives together with 5-50 wt % of aromatics and olefins. The major challenge for separating the sulfur compounds from the transportation fuels is to find a suitable adsorbent that selectively adsorbs the sulfur compounds under ambient conditions leaving the coexisting aromatics and olefins intact. The thiophenic sulfur compounds can be adsorbed either by p complexation using the delocalized p electrons of the thiophenic ring or by the formation of h1S or S-m3-bonding using unshared electrons present on the sulfur atom. In the present research, new adsorbents that will selectively adsorb thiophenic sulfur compounds by the formation of h1S or S-m3-bonding will be designed and tested. The adsorbed sulfur compounds will be recovered by washing the spent adsorbent with a suitable solvent followed by evaporation of the solvent. The concentrated sulfur compounds will be hydrodesulfurized in a small HDS reactor using a new and advanced HDS catalyst developed in this project. New adsorbents based on hydrotalcite-like anionic clays, metal compounds supported porous materials and nano-sized metal sulfides will be synthesized and their adsorption performance will be evaluated using a fixed-bed adsorption device. New HDS catalysts containing Ni, Co and Mo with higher metal loading on mesoporous supports such as MCM-41 and SBA-15 will be designed and their performance will be evaluated in the HDS of concentrated sulfur compounds. Quantum chemical calculations using semi-empirical quantum chemistry method in computer aided chemistry (CAChe) molecular orbital package (MOPAC) and/or density functional theory (DFT) will be employed to understand the fundamentals of surface adsorption-desorption mechanism for the development of a novel sulfur-selective adsorbent and also to reveal the key factors involved in the HDS of concentrated refractory sulfur fraction over the new, laboratory-made catalysts and the commercial HDS catalysts. Based on this work, a new desulfurization technology integrating the adsorption of sulfur compounds under ambient conditions by SARS process in the first step and a small scale HDS of concentrated refractory sulfur compounds obtained from regeneration of the spent adsorbent by solvent washing in the second step will be developed to produce ultra-clean transportation fuels.
Progress Summary:
In Year 2 of the project, our work focused on the fundamental understanding of the inherent adsorptive selectivity and adsorptive mechanism of various typical adsorbents on the basis of the experimental and computational approaches. Our accomplishments include the following:
- The adsorptive selectivity and performance, including capacity and selectivity, of more than 20 promising adsorbents were evaluated in a batch adsorption system.
- The adsorptive selectivity and mechanism of the typical nickel-based adsorbent was further studied in detail in a fixed bed adsorption system. It was found that the direct interaction between the heteroatom in the adsorbate and the surface nickel plays an important role, indicating that the nickel-based adsorbent is an excellent one for selective removal of the sulfur compounds, which have no alkyl steric hindrance, from hydrocarbon streams, such as gasoline, kerosene, and jet fuel. However, even with the nickel-based adsorbent, it is still difficult to remove the alkyl dibenzothiophenes with methyl groups at the 4- and/or 6-positions because of the steric hindrance of the alkyl groups, which indicates that the nickel-based adsorbent might not be quite as effective for deep desulfurization of commercial diesel.
- The adsorptive selectivity and mechanism of the activated alumina were further studied in detail in a fixed bed adsorption system. It was found that the adsorption selectivity depends predominantly on the electrostatic interaction and the acid-base interaction. The activated alumina is very effective for selective separation of the nitrogen compounds in liquid hydrocarbon fuels, especially for basic nitrogen compounds, but not very successful for separating the sulfur compounds from hydrocarbon streams.
- The adsorptive selectivity and mechanism of the activated carbon was further studied in detail in a fixed bed adsorption system. The results show that the activated carbon shows higher adsorptive capacity and selectivity for both sulfur and nitrogen compounds, especially for the refractory sulfur compounds in the commercial diesel. The hydrogen bonding interaction involving surface oxygen functional groups might play an important role in adsorptive desulfurization and denitrogenation over the activated carbon. The study suggests that the carbon material might be one of most promising adsorbents for removing sulfur from the commercial diesel.
- By comparative study of different adsorbents, we found that different adsorbents may be suitable for separating different sulfur compounds from different hydrocarbon streams. The combination of two or more adsorbents in an adsorptive desulfurization process might be a trend for a practical ultra-deep desulfurization process of liquid hydrocarbon fuels.
On the basis of these approaches, we understand and clarify further the adsorptive desulfurization mechanism of the thiophenic sulfur compounds in liquid hydrocarbon fuels over the different typical adsorbents and the effects of the co-existing aromatic and nitrogen compounds on the adsorptive performance. The present study provided a close insight into the fundamental adsorption mechanism of the sulfur compounds over the different typical adsorbents through both experimental and computational approaches. These approaches improve our knowledge on the adsorptive desulfurization and provide a great amount of scientific data and information for improving our current adsorbents and, moreover, for design and preparation of the more efficient adsorbents for deep desulfurization of liquid hydrocarbon fuels. According to the new findings in this project, we have published five science articles in prestigious journals, and given eight presentations at the international and national conferences.
Expected Results:
The proposed research can change the way of thinking in the field and lead to the development of a more efficient, economical and novel technology for the production of sulfur-free ultra-clean transportation fuels, meeting the current and future EPA regulations for the automotive fuels as well as for future fuel cell cars. The new technology developed will significantly contribute to achieving sustainable long-term economic growth while maintaining a cleaner environment. This research will significantly contribute to the improvement of the global air quality and minimize the public health hazards due to the sulfur poisons. The proposed work in molecular simulation will result in the application of advanced computational molecular simulation technology to the investigation of adsorptive desulfurization and HDS. The method developed will enable us to estimate heat of adsorption and to explore adsorptive mechanisms of various compounds over solid surface. It will greatly improve our knowledge in adsorption on solid surface and result in using the advanced computational molecular simulation methodology to predict the potential adsorbents and to guide the experiments. Consequently, it can lead to a huge saving in time, money, and other resources.
Future Activities:
As shown in the previous annual report and the present annual report, the carbon material might be one of the most promising adsorbents for removing sulfur from commercial diesel. In Year 3, we will develop some new carbon materials to increase the adsorption capacity and selectivity for the refractory sulfur compounds in commercial diesel. The physical and surface chemical properties of carbon materials will be characterized by BET, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and other methods; then these properties will be correlated with their adsorption performance. The regeneration of spent carbon materials will also be studied.
Journal Articles on this Report : 5 Displayed | Download in RIS Format
Other project views: | All 28 publications | 13 publications in selected types | All 13 journal articles |
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Kim JH, Ma X, Song C. Kinetics of two pathways for 4,6-dimethyldibenzothiophene hydrodesulfurization over NiMo, CoMo sulfide, and nickel phosphide catalysts. Energy & Fuels 2005;19(2):353-364. |
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Kim JH, Ma X, Zhou A, Song C. Ultra-deep desulfurization and denitrogenation of diesel fuel by selective adsorption over three different adsorbents:a study on adsorptive selectivity and mechanism. Catalysis Today 2006;111(1-2):74-83. |
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Ma X, Sprague M, Song C. Deep desulfurization of gasoline by selective adsorption over nickel-based adsorbent for fuel cell applications. Industrial & Engineering Chemistry Research 2005;44(15):5768-5775. |
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Ma X, Velu S, Kim JH, Song C. Deep desulfurization of gasoline by selective adsorption over solid adsorbents and impact of analytical methods on ppm-level sulfur quantification for fuel cell applications. Applied Catalysis B:Environmental 2005;56(1-2):137-147. |
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Velu S, Song CS, Engelhard MH, Chin Y-H. Adsorptive removal of organic sulfur compounds from jet fuel over K-exchanged NiY zeolites prepared by impregnation and ion exchange. Industrial & Engineering Chemistry Research 2005;44(15):5740-5749. |
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Supplemental Keywords:
desulfurization, adsorption, hydrodesulfurization, gasoline, jet fuel, diesel, liquid hydrocarbon, adsorbent,, RFA, Scientific Discipline, Air, Sustainable Industry/Business, Sustainable Environment, Environmental Chemistry, Technology for Sustainable Environment, mobile sources, engine exhaust, motor vehicles, Nox, selective adsorption for removing sulfur, hydrodesulfurization, desulfurization, air pollutants, automotive emissions, sulfur, diesel exhaust, fuel cell, alternative fuel, alternative motor fuels, diesel fuel, pollution preventionProgress and Final Reports:
Original AbstractThe 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.