Grantee Research Project Results
2004 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 , Clemons, Jennifer L , Subramani, Velu , 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, 2003 through December 11,2004
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 using a combined experimental and computational analysis. The specific objectives of this research project for the present period are to: (1) understand the adsorption mechanism of nickel (Ni)-based adsorbent; (2) clarify effects of the coexisting species in fuel and adsorption conditions on adsorptive performance; and (3) investigate fundamental effects of the preparation methods and the surface chemical structure of Ni-based adsorbents on their adsorption performance.
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 1 of the project, our approaches focused on: (1) developing Ni-based adsorbents; and (2) understanding the adsorptive mechanism and the interaction between the surface structure of Ni-based adsorbents and their adsorptive performance. Our accomplishments included the following:
- More than 10 Ni-based adsorbents were prepared and tested. These Ni-based adsorbents include Ni-aluminum (Al) material, Ni/SiO2-Al2O3, Ni-loaded Yttrium zeolite adsorbents with different loading (0.5-45 wt%) and different methods (ion-exchange, incipient wetness impregnation).
- Adsorptive desulfurization performances of the different Ni-based adsorbents, including the adsorptive capacity and selectivity, were examined by using different fuels in a fixed bed adsorption system.
- The sulfur compounds, coexisting aromatic and olefinic compounds in fuels and some desulfurization products in the treated fuels, were identified and quantified by gas chromatography- flame ionization detector and gas chromatography-pulsed flame photometric detector for selectivity analysis and mechanistic discussion.
- Quantum chemical calculations of the sulfur compounds and some coexisting aromatic and olefinic compounds—including electron density, electrostatic potential, bond order, charge distribution, and molecular orbits analysis—were conducted for selectivity analysis and mechanistic understanding.
- The different Ni-based adsorbents were characterized by temperature-programmed reduction and in-situ X-ray photoelectron spectroscopy to explore the relationship between their surface chemistry properties and their adsorptive performance.
On the basis of the preparation, characteristics, and evaluation of the different Ni-based adsorbents and computational analysis, we understand and clarify: (1) the adsorptive desulfurization mechanism of the thiophenic sulfur compounds in gasoline and jet fuel over the different Ni-based adsorbents; (2) the effects of different co-existing aromatic and olefinic compounds as well as adsorption operation conditions on the adsorptive performance; and (3) how the different preparation methods influence the surface nature of the adsorbents, and finally, influence their adsorptive performance. These research approaches provide a great amount of scientific data and information for improving the current Ni-based adsorbents and, moreover, for design and preparation of the novel Ni-based adsorbent with higher capacity and selectivity for deep desulfurization.
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:
The adsorptive desulfurization of diesel fuel over the Ni-based adsorbents will be conducted along with activated carbon and activated alumina in the future work. As the major sulfur compounds in the commercial diesel fuel the dibenzothiophene with one or two alkyl groups at 4- and/or 6-positions. We expect that these sulfur compounds might be diff icult to remove using the Ni-based adsorbents because of the steric hindrance of the alkyl groups. Thus, other types of adsorbents will also be explored. We also will explore the regeneration of the spent adsorbents and hydrodesulfurization of the refractory sulfur fraction.
Journal Articles:
No journal articles submitted with this report: View all 28 publications for this projectSupplemental Keywords:
desulfurization, adsorption, gasoline, jet fuel, adsorbent, mechanism, selectivity, characterization,, 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.