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Final 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 , Kim, Jae Hyung , Ma, Xiaoliang , Subramani, Velu , Sundararaman, Ramanathan , Wang, Xiaoxing , Yoosuk, Boonyawan , Zhou, Anning
Institution: Pennsylvania State University - Main Campus
EPA Project Officer: Bauer, Diana
Project Period: October 15, 2003 through October 14, 2006 (Extended to August 31, 2007)
Project Amount: $325,000
RFA: Technology for a Sustainable Environment (2003)
Research Category: Pollution Prevention/Sustainable Development
Description:
Objective:The overall objectives of this project comprise of 1) designing new adsorbents with high selectivity for removing sulfur compounds from transportation fuels under ambient temperature and pressure, 2) developing new and advanced catalysts for the HDS of concentrated sulfur fractions, and 3) understanding the fundamentals of adsorption-desorption and catalytic HDS processes by a combination of experimental and computational analysis. The 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.
Summary/Accomplishments (Outputs/Outcomes):In the whole period of performance, our approaches focused on the following aspects: 1) developing the Ni-based adsorbents and understanding the adsorptive mechanism and the interaction between the surface structure of the Ni-based adsorbents and their adsorptive performance; 2) fundamental understanding of the inherent adsorptive selectivity and adsorptive mechanism of other adsorbents such as activated carbons and activated alumina with and without oxidative modification; 3) the oxidative desulfurization performance of various catalysts by molecular oxygen (with the option of subsequent adsorption) at mild conditions; and 4) preparation and characterization of nano-sized bimetallic sulfide catalysts without using any support materials for deep hydrodesulfurization of deep hydrodesulfurization of 4,6-dimethyldibenzothiophene.
- More than 20 Ni-based adsorbents were prepared and tested. These Ni-based adsorbents include Ni-Al materials (A2 adsorbents), Ni-Al and Ni-Zn-Al materials from a double layered hydroxide intermediate (A4 adsorbents), Ni/SiO2-Al2O3, Ni-loaded Y zeolite adsorbents with different loading (0.5-45 wt%) and different methods (ion-exchange, incipient wetness impregnation) and commercial Ni-based adsorbents (A5 adsorbents).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.
- 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, and the characterizations by various technologies were conducted for selectivity analysis and mechanistic understanding over these Ni-based adsorbents.
- 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, the nickel-based adsorbent is still difficult to remove the alkyl DBTs with methyl groups at the 4 and/or 6 positions due to the steric hindrance of the alkyl groups, It indicates that the nickel-based adsorbent might not quite effective for deep desulfurization of commercial diesel.
- The adsorptive selectivity and mechanism of the activated alumina was studied in detail in a fixed bed adsorption system. It was found that the adsorption selectivity depends dominantly 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 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 carbons. The study suggests that the carbon material might be one of most promising adsorbents for removing sulfur from the commercial diesel.
- The modification of activated carbons (AC) was conducted by liquid-phase HNO3-oxidation and gas-phase O2-oxidation. The oxidation modified AC samples were further characterized by N2 physisorption, SEM, FTIR, XPS and surface pH measurement technologies. The oxidative modification can significantly improve their adsorptive desulfurization performance, through an increase of the oxygen-containing functional groups, especially carboxyl groups, on the AC surface. The results strongly indicate that the adsorption of the sulfur compounds on oxidative modified ACs may be conducted through the hydrogen bonding and/or acid-base interaction mechanism.
- More than 10 promising heterogeneous catalysts were synthesized by different preparation methods. Oxidative desulfurization of model diesel fuels over these catalysts by using O2 as the oxidant was conducted in a batch adsorption system. At 140 °C without catalyst, most sulfur compounds in diesel fuels can be oxidized to corresponding sulfones which are easily removed by adsorption. However other hydrocarbons in the fuels were also oxidized and the selectivity was poor. Using catalysts could significantly reduce the reaction temperature and increase the relative selectivity to the sulfur compounds.
- By comparative study of different adsorbents, we found that different adsorbents may be suitable for separating different sulfur compounds from different hydrocarbon streams. Combination of two or more adsorbents in an adsorptive desulfurization process or combination of the ODS and adsorption process might be a trend for a practical ultra-deep desulfurization process of liquid hydrocarbon fuels.
- For the HDS catalyst study, new bimetallic dispersed metal sulfide catalysts have been prepared using a new hydrothermal synthesis method. The results show that unsupported CoMoS2 and NiMoS2 dispersed nano-particulate catalysts have been syn thesized and they exhibit excellent catalytic activities that are superior to the commercial hydrotreating catalysts for deep hydrodesulfurization of 4,6-dimethyldibenzothiophene.
On the basis of these approaches, we understand and clarify 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.
Based on the new findings from this project, we have published/submitted nine journal articles in prestigious journals, and given nine presentations at the international and national conferences.
Journal Articles on this Report: 8 Displayed | Download in RIS Format
| Other project views: | All 18 publications | 9 publications in selected types | All 8 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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Ma X, Zhou A, Song C. A novel method for oxidative desulfurization of liquid hydrocarbon fuels based on catalytic oxidation using molecular oxygen coupled with selective adsorption. Catalysis Today 2007;123(1-4):276-284. |
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Velu S, Song C, 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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Yoosuk B, Kim JH, Song C, Ngamcharussrivichai C, Prasassarakich P. Highly active MoS2, CoMoS2 and NiMoS2 unsupported catalysts prepared by hydrothermal synthesis for hydrodesulfurization of 4,6-dimethyldibenzothiophene. Catalysis Today 2008;130(1):14-23. |
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Zhou A, Ma X, Song C. Liquid-phase adsorption of multi-ring thiophenic sulfur compounds on carbon materials with different surface properties. Journal of Physical Chemistry B 2006;110(10):4699-4707. |
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Desulfurization, adsorption, oxidative desulfurization, gasoline, jet fuel, diesel, liquid hydrocarbon, adsorbent, Ni, activated carbon, catalyst, selective adsorption for removing sulfur,
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POLLUTANTS/TOXICS, INTERNATIONAL COOPERATION, Air, Sustainable Industry/Business, Scientific Discipline, RFA, Technology for Sustainable Environment, Sustainable Environment, Chemical Engineering, Chemicals Management, Chemicals, Environmental Chemistry, mobile sources, engine exhaust, fuel cell, sulfur, alternative motor fuels, diesel exhaust, green chemistry, hydrodesulfurization, Nox, air pollutants, diesel fuel, motor vehicles, automotive emissions, alternative fuel, desulfurization, selective adsorption for removing sulfur
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Progress and Final Reports:
Original Abstract