Abstract:

Effects of 1,5-hexadiene and benzene on the desulfurization property of NiY were investigated by Fourier transform-infrared (FT-IR), frequency-response (FR), and fixed-bed techniques. Results indicate that both 1,5-hexadiene and benzene inhibit the desulfurization of the sorbent which can be detected by a decrease in the desulfurization capacity of the NiY in the presence of 1,5-hexadiene and benzene in the model fuels. The effect of benzene on the adsorption capacity of the NiY was more conspicuous than that of 1,5-hexadiene. In the zeolite, the sulfur compounds and 1,5-hexadiene adsorbed on the protons can subsequently undergo an opening reaction of the heterocyclic rings, which blocks the zeolite pores and then hinders sulfide molecule access to the supercage where they could come into contact with metal cations. Distinct processes were observed in the FR spectra of thiophene and benzene on NiY zeolites, with the adsorption of thiophene in the supercage being the rate-controlling step and the diffusion process of benzene in the supercage being the rate-controlling step. The benzene molecules were replaced by thiophene molecules from the active centers and they, therefore, diffused out of the zeolite channels with difficulty. The adsorption of thiophene into the active centers will, therefore, be hindered.

Key words: Desulfurization, Frequency-response, Zeolite, Catalytic reaction, Diffusion