Aromatics/Aliphatics Separation by Adsorption:  New Sorbents for Selective Aromatics Adsorption by π-Complexation

Takahashi, Akira; Yang, Frances H.; Yang, Ralph T.

doi:10.1021/ie000376l

Cited by 76 publications

(65 citation statements)

References 40 publications

(73 reference statements)

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“…This type of bonding is broadly referred to as -complexation. For example, CuCl, which is insoluble in water, has been considered in the power form for olefin/paraffin separation [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of AgCl/PMMA hybrid membranes and their sorption performance of cyclohexane/cyclohexene

Shen

Zheng

Ruan

et al. 2007

Journal of Membrane Science

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Section: Introductionmentioning

confidence: 99%

Synthesis of AgCl/PMMA hybrid membranes and their sorption performance of cyclohexane/cyclohexene

Shen

Zheng

Ruan

et al. 2007

Journal of Membrane Science

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“…Therefore, this provides opportunities for tailoring and developing new adsorbents for processes where selective adsorption is needed, such as in the case of sulfur removal from fuels. Our group has already developed -complexation adsorbents for desulfurization Takahashi et al, 2002; Yang, 2003a, 2003b), olefin/paraffin, diene/olefin, and aromatics/aliphatics separations (Yang and Kikkinides, 1995;Rege et al, 1998;Huang et al, 1999aHuang et al, , 1999b Yang, 1997, 2000;Padin et al, 1999;Jayaraman et al, 2001;Takahashi et al, 2000Takahashi et al, , 2001. Hernández-Maldonado and Yang (2003a) found that both copper and silver exchanged faujasite type zeolites, Ag-Y and Cu(I)-Y, are excellent adsorbents for the removal of thiophene molecules from liquid hydrocarbon mixtures.…”

mentioning

confidence: 99%

New sorbents for desulfurization of diesel fuels via π‐complexation

2004

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Desulfurization of a commercial diesel fuel by different adsorbents was studied in a fixed-bed adsorber operated at ambient temperature and pressure. In general, the adsorbents tested for total sulfur adsorption capacity at breakthrough followed the order: AC/Cu(I)-Y Ͼ Cu(I)-Y Ͼ Selexsorb CDX (alumina) Ͼ CuCl/␥-Al 2 O 3 Ͼ activated carbon Ͼ Cu(I)-ZSM-5. The best adsorbent, AC/Cu(I)-Y (layered bed of 15 wt % activated carbon followed by Cu(I)Y), is capable of producing 30 cm 3 of diesel fuel per gram of adsorbent with a weighted average content of 0.15 ppmw-S, and about 20 cm 3 of diesel fuel per gram of adsorbent with a weighted average content of 0.06 ppmw-S. These low-sulfur fuels are suitable for fuel cell applications. The added layer of carbon not only delayed the sulfur breakthrough significantly but also sharpened the sulfur wavefronts. GC-FPD results showed that the -complexation sorbents selectively adsorbed highly substituted thiophenes, benzothiophenes, and dibenzothiophenes from diesel, which is not possible with conventional hydrodesulfurization (HDS) reactors. The high sulfur selectivity and high sulfur capacity of Cu(I)Y were because of -complexation. © 2004 AmericanInstitute of Chemical Engineers AIChE J, 50: [791][792][793][794][795][796][797][798][799][800][801] 2004 Keywords: desulfurization of liquid fuels, -complexation sorbent, desulfurization by adsorption, desulfurization of diesel, 4-methyl-dibenzothiophene adsorption, 4, 6-dimethyl- dibenzothiophene adsorption IntroductionThe federal government mandates a reduction in gasoline and diesel sulfur levels to 30 and 15 ppm, respectively, from the current levels of 300 -500 ppmw, to be implemented by 2006(Krause, 2000. This makes refiners consider eliminating production of onboard transportation fuels because of the high costs that will arise from compliance with such regulations (Parkinson, 2001). For fuel cell applications with gasoline as the feed, the sulfur content should be below 1 ppmw. For automotive fuel cells, liquid hydrocarbons are ideal fuels because of their higher energy density, availability, and safety for transportation and storage. However, the water-gas shift catalysts as well as fuel-cell electrode catalysts are poisoned by sulfur, and the sulfur content in the liquid fuel needs to be preferably less than 0.1 ppmw.Hydrodesulfurization (HDS) is very effective in removing thiols and sulfides, but it is not effective for the removal of thiophenic compounds. For example, the H 2 S produced during reaction of some thiophene derivatives is one of the main inhibitors for deep HDS of unreactive species (Ma et al., 1994;Knudsen et al., 1999). Among the unreacted refractory species are 4-methyl-dibenzothiophene (4-MDBT) and 4,6-dimethyldibenzothiophene (4, 6-DMDBT). These molecules are common in diesel fuels. The methyl groups in these species create a steric effect that hinders the capacity of HDS catalysts to chemisorb the sulfur atoms as depicted in Figure 1a. Such steric hindrance is not present for adsorption by -complexatio...

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“…[37][38][39] The second approach is to use a smallmolecule analogue of the binding site and apply spectroscopic and/or molecular modeling methods to study interactions between solutes and the analogue. 40,41 In previous studies, we used ethylpropionate (EP) as a small-molecule analogue of the acrylic ester's binding site. 6,7,28,42 Experimentally, we used infrared (IR) spectroscopy to measure shifts in the O-H stretching frequency that result from hydrogen bonding.…”

Section: Results and Discusssionmentioning

confidence: 99%

Enhanced Hydrogen Bonding for the Adsorptive Recovery and Separations of Oxygenated Aromatic Compounds from Renewable Resources

Brown

Chen

Embree

et al. 2002

Ind. Eng. Chem. Res.

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Chemicals that are available from renewable resources typically contain heteroatoms that make hydrogen bonding a prominent intermolecular interaction. We are examining how hydrogen bonding can be exploited as an adsorption mechanism to facilitate the recovery and separations of oxygenated aromatic compounds from renewable resources. Specifically, we examined the adsorption of compounds that have weak or attenuated hydrogen-bonding abilities. The solvent in our study was hexane, which is commonly used in the food industry to extract chemicals from plant material (e.g., for vegetable oils and flavor extracts). The low dielectric constant of hexane also facilitates the hydrogen-bonding adsorption mechanism. Three polymeric adsorbents of differing basicities were studied, an acrylic ester sorbent (XAD-7, Rohm and Haas), a pyridine sorbent (Reillex 425, Reilly Industries), and a tertiary amine sorbent (IRA-93, Rohm and Haas). Adsorption affinities (related to the adsorption equilibrium constant, K eq ) and adsorption enthalpies (-∆H°) were observed to increase with increasing basicity of the sorbent's binding site. Infrared spectroscopy was used to study the interaction mechanism between the solutes and small-molecule analogues of the binding sites for the three sorbents. These studies support the conclusion that the observed increase in adsorption results from increased hydrogen-bond strengths. These results indicate that, by adjusting the hydrogen-bond accepting abilities of the adsorbent, it is possible to alter adsorption affinities to balance the dual objectives of recovery and selectivity.

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Aromatics/Aliphatics Separation by Adsorption: New Sorbents for Selective Aromatics Adsorption by π-Complexation

Cited by 76 publications

References 40 publications

Synthesis of AgCl/PMMA hybrid membranes and their sorption performance of cyclohexane/cyclohexene

Synthesis of AgCl/PMMA hybrid membranes and their sorption performance of cyclohexane/cyclohexene

New sorbents for desulfurization of diesel fuels via π‐complexation

Enhanced Hydrogen Bonding for the Adsorptive Recovery and Separations of Oxygenated Aromatic Compounds from Renewable Resources

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