科研之友
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摘要
Adsorption, coadsorption, and reactions of sulfur compounds, olefins, and aromatics over Ce-exchanged Y zeolite (CeY) have been studied by N-2 adsorption, intelligent gravimetric analyzers (IGA), X-ray diffraction (XRD), inductively coupled plasma mass spectrometry (ICP-MS), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FT-IR), frequency response (FR) techniques, and batch and fixed bed methods. The coadsorption of olefins can effectively contribute to the alkylation and oligomerization reactions of thiophene and further decrease the desulfurization performance of CeY. The influence of aromatics on the desulfurization performance of CeY can be related to the competitive adsorption/diffusion processes between sulfur compounds and aromatics. The diffusion process is the rate-controlling step for benzene, and the sorption process is the rate-controlling step for thiophene. Thiophene molecules can be preferentially adsorbed onto the Lewis acid sites by direct interaction between sulfur on sulfur compounds and the Ce ion (S-M bond formation) or pi-complexation, but the S-M bond interactions play a more dominant role than pi-complexation in the CeY/sulfur compounds system.
