Adsorption And Photocatalytic Under Visible Light Irradiation Desulfurization Activity Of G-C₃N₄ In Isooctane

In recent years,the problems of environment and energy become increasingly prominent,so the desulfurization of fuel has become a hot issue in the field of petrochemical industry.Adsorption and photocatalytic desulfurization as a new kind of desulfurization technology has caused wide concern due to their mild reaction condition,low cost and high selectivity.g-C₃N₄ is a new type of visible light photocatalyst and widely applied in the field of photocatalytic H2 evolution,CO2 reduction and degradation.In this dissertation,g-C₃N₄ was used as adsorbent and photocatalyst,with Pt-loaded and adjusted micro-structures.The photocatalytic and adsorption desulfurization activity were also investigated.The main contents are discussed as follow:?1?g-C₃N₄ was synthesized by directly direct-heating melamine at 600?.Morphology and optical absorption were investigated by XRD,IR,TEM and UV-Vis,and the band gap of g-C₃N₄ is 2.75 e V estimated through UV-vis diffuse reflection spectrum.Different amount of Pt?wt%=0.01%,0.1%,0.5%?was deposited on g-C₃N₄ by impregnation method to enhance the photocatalytic desulfurization performance.The experimental results show that 0.1-wt%-Pt/ g-C₃N₄ sample possesses the best the photocatalytic desulfurization activity,whose desulfurization ratio reaches to 76.8% under visible light irradiation after180 mins' irradiation.The photocatalytic reaction could not occur when the light source was covered by a 600 nm cut-off filter,indicating this desulfurization reaction is not an adsorptive but a photocatalytic oxidative reaction,The mechanism of photocatalytic desulfurization was also deduced through a contrast experiment.?2?Mesoporous g-C₃N₄ was synthesized by directly heating dicyandiamide at 600?,and colloidal Si O2 was used as a template agent.When the hard template was removed by HF,different sizes of mesoporous g-C₃N₄ were obtained.The morphologies of adsorbents were investigated by XRD,IR and TEM.The impact of specific surface area and initial concentration on adsorption desulfurization were studied.The results indicate that mesoporous g-C₃N₄-4.5nm sample possesses the best the adsorption desulfurization activity,and the adsorption activity come worse with the increase of pore size and initial concentration.The mechanism of adsorption desulfurization was also analyzed.The results of TPD show that the adsorption activities increases with the increase of H+.Gaussian calculation indicates acidizing increased the positive electricity of ortho-C,which possibly acts as the active sites for thiophene adsorption.?3?Pt?wt%=0.1%?was deposited on mesoporous g-C₃N₄ under the irradiation of Xe-light.The structures,compositions morphology and optical properties of synthesized sample were characterized by XRD,IR,TEM,UV-Vis.Mesoporous Pt/ g-C₃N₄-4.5nm possesses the best the photocatalytic desulfurization activity,whose desulfurization ratio reaches to 88.3% under visible light irradiation after 180 mins' irradiation.The photocatalytic desulfurization activity of mesoporous Pt/g-C₃N₄ decreases with the increase of pore size.The kinetic curves of photocatalytic desulfurization show that it is not in conformity with the first order kinetics.This result indicates that the concentration of solution and diffusion also influence the reaction rate.