Preparation of mesoporous Co-MCM-41 and its performance in adsorption removal of various basic nitrogen compounds

The mesoporous materials MCM-41 and Co-MCM-41, with Co/Si(molar ratio)=0.18, were prepared by hydrothermal synthesis method with cobalt nitrate as cobalt source and characterized by X-ray diffraction (XRD), fourier transform infrared spectrometry (FT-IR) and nitrogen adsorption-desorption.XRD and FT-IR results indicated that Co was introduced into the framework of mesoporous materials.The MCM-41 and Co-MCM-41 with highly ordered hexagonal mesoporous structure had been synthesized when the Co/Si(molar ratio) was 0.18 or less.But the sample had lost its ordered hexagonal mesoporous structure when Co/Si(molar ratio) was 0.22, indicating that the maximum addition amount of Co was about Co/Si(molar ratio)=0.18 when Co-MCM-41 was synthesized by using cobalt nitrate as cobalt source.Compared with the MCM-41, the intensity of XRD peak (100) of Co-MCM-41 became weak, broad and its surface area and total pore volume decreased, but the average pore diameter increased with the increase of Co amount.However, there was small amount of highly dispersed Co₃O₄ on the channel surface of Co-MCM-41 samples when the Co/Si(molar ratio) was 0.06 or more.Denitrification of model fuels containing about 1737.35 μg(nitrogen)/g of quinoline, aniline or pyridine was studied over the synthesized Co-MCM-41 with static adsorption at ambient conditions.The sequence of adsorption denitrification performance over all Co-MCM-41 samples was aniline, pyridine and quinoline.The adsorption capacity of Co-MCM-41(0.06) for aniline, pyridine and quinoline was 42.17, 35.66 and 29.18 mg(N)/g and the removal rate of basic nitrogen was 82.38%, 73.53% and 61.11% respectively.The coexisting aromatic compounds in model fuel had little impact on the removal performance of basic nitrogen over Co-MCM-41(0.06), implying that the N-M bond between the adsorption sites and N atom in the compound plays a significant role.Furthermore, Co-MCM-41 could be easily regenerated its adsorption denitrification performance by using calcination or ethanol regeneration method.