(460e) Denitrogenation of Diesel Fuel by Adsorption On MCM-41, Al MCM-41 and Cu-MCM-41: A Kinetic Study

Denitrogenation of diesel fuel by adsorption on MCM-41, Al MCM-41 and Cu-MCM-41: a kinetic study
J.F. Guayaquil-Sosa, C.O. Castillo-Araiza, F. López-Isunza and J.A. de los Reyes-Heredia
Autonomous Metropolitan University-Iztapalapa
Av. San Rafael Atlixco 186 Col. Vicentina. C.P. 09340. Iztapalapa, México City;
tel. +521 5558044600-1243,
e-mail: fabricio@xanum.uam.mx;

Summary

The remotion of nitrogen compounds from diesel fuel before hydrodesulfurization (HDS) has captured attention because these compounds strongly inhibit the HDS of some refractory sulfur molecules such as 4-methyldibenzothiophene (4-MDBT), 4,6-dimethyldibenzothiophene (4,6-DMDBT), etc.

In this work a set of adsorbents based on mesoporous molecular sieves; for instance, MCM-41, Al-MCM-41 and Cu-MCM-41 were synthesized, characterized and evaluated, adsorbing model molecules (quinoline and indole) for remotion of nitrogen compounds present in diesel fuel. These experiments were carried out in a laboratory batch stirred tank (15 ml) agitated at 300 rpm, room temperature, and a concentration of nitrogen-containing molecule of 300 ppmw dissolved in a mixture of hexadecane-toluene (1:1).

The performances of synthesized solids were compared with that for a commercial adsorbent (selexsorb CDX) based on γ-Al2O3-zeolite. Materials were characterized by using DRX, N2 Physisorption, Temperature-Programmed Desorption of Pyridine (TPD-Py) and High-Resolution Transmission Electron Microscopy (HR-TEM).

Kinetic models based on Langmuirian mechanism were developed. The adsorption parameters were estimated by using the Levenberg-Marquardt method, and they suggested the quinoline was selectively more adsorbed than indole. Quinoline adsorption constants for Al-MCM-41 adsorbent were higher than the ones for the commercial adsorbent, suggesting that the synthesized material could be used as industrial adsorbent to remove quinoline. On the other hand, indole adsorption constants for Cu-MCM-41 material were higher than the commercial one.

Materials based on mesoporous molecular sieves such as Al-MCM-41 and Cu-MCM-41 appeared promising adsorbents for the removal of nitrogenated compounds, compared to the commercial CDX.