Preparation and adsorption denitrification of heteroatoms mesoporous molecular sieve Co-MCM-41

The MCM-41 and Co-MCM-41 molecular sieves, prepared by hydrothermal synthesis method, were characterized with X-ray diffraction (XRD), Fourier transform infrared spectrum (FT-IR), nitrogen adsorption and NH₃-TPD. The effects of aging time, crystallization temperature, crystallization time on the crystallization process of MCM-41 and Co-MCM-41 molecular sieves were investigated. The optimal conditions were as follows: 1 h of aging time, 110 ℃ of crystallization temperature and 2 d of crystallization time. XRD and FT-IR results indicated that Co was introduced into the framework of MCM-41. Brunauer-Emmett-Teller (BET) surface area and pore volume of MCM-41 and Co-MCM-41 were 986.42 m²/g, 637.69 m²/g, 0.762 1 m³/g and 0.537 2 m³/g respectively. The average pore diameter was 2.82 nm for both of MCM-41 and Co-MCM-41. The results of TPD showed that although MCM-41 and Co-MCM-41 possessed weak acidity, the acidity of Co-MCM-41 was stronger than MCM-41. Denitrification of model fuels containing about 1 737.35 μg(nitrogen)/g (16.03 mg(quinoline)/g) was studied over the synthesized MCM-41 and Co-MCM-41 with static adsorption at ambient conditions. The molecular size of quinoline, calculated by using density functional theory (DFT), was 0.711 6 nm×0.500 2 nm, implying that the quinoline easily access to the mesopores of MCM-41 and Co-MCM-41. The removal rate of basic nitrogen by Co-MCM-41 was clearly higher than MCM-41 due to its strong acidity and chemisorption between Co-MCM-41 and quinoline. Furthermore, Co-MCM-41 could be easily regenerated.