Abstract
Abstract - The synthesis and characterization of a mesoporous molecular sieve (MCM-41) was studied due to its high surface area and large pore volume and to target potential applications in adsorption and catalysis. Ra-re earth elements have special chemical properties and are efficient promoters for supports. In this study, a mesoporous molecular sieve that incorporates the transition metal cerium (Ce-MCM-41) was synthesized us-ing the hydrothermal method with the goal of improving the structural properties for adsorption. The molar composition of the obtained gel was 1CTMABr: 4SiO 2 : 1Na 2 O: 0.2Ce 2 O 3 : 200H 2 O. The pure mesoporous molecular sieve MCM-41 was also synthesized using the same method. The materials were characterized by the following techniques: XRD, BET/BJH, SEM/EDS, TG and FT-IR. A preliminary test to evaluate the mate-rials as adsorbents to remove naphthenic acids present in jet fuel was performed. The results of the characteri-zation showed that the incorporation of the metal cerium did not affect the MCM-41 structure and that mesporous materials were formed. Ce-MCM-41 exhibited good thermal stability, high specific surface area and large pore volume, which are characteristics of a good adsorbent. From the preliminary test, the adsorp-tive capacity increased by 60% with the incorporation of cerium in the MCM-41 structure.
Highlights
The mesoporous molecular sieve MCM-41, which is a member of the M41S family, was first discovered by the Mobil Company in 1992 to eliminate diffusion pore restrictions present in zeolites due to its micropores, which limit its use with larger molecules for adsorption and catalytic conversions (Beck et al, 1992; Corma et al, 1997)
The X-ray diffraction pattern of MCM-41 showed the presence of a strong diffraction peak (100) at 2θ = 2.17° and two low intensity peaks at (110) and (200) of 3.69° and 4.27°, which indicates the formation of orderly mesoporous material
The X-ray diffraction pattern of Ce-MCM-41 showed the presence of these peaks at (100), (110) and (200) 2θ = 2.00°, 3.48° and 4.04°, respectively, which indicates that the structure of hexagonal MCM-41 was maintained after introducing cerium into its structure
Summary
The mesoporous molecular sieve MCM-41, which is a member of the M41S family, was first discovered by the Mobil Company in 1992 to eliminate diffusion pore restrictions present in zeolites due to its micropores, which limit its use with larger molecules for adsorption and catalytic conversions (Beck et al, 1992; Corma et al, 1997).Since much interest has been focused on their properties and applications due to the hexagonal arrangement, their high specific surface areas, narrow pore size distribution and controllable and wide spectrum of pore diameters (15-100 Å) in the mesoporous region (Jiang et al, 2007; Zhao et al, 2011).The mesoporous molecular sieves can be applied in areas of catalysis and adsorption, can control pollution in the environment (Hao et al, 2006; Qin et al, 2007; Puanngama and Unob, 2008) and can be used in technology that employs advanced materials based on molecular sieves, such as electron transfer photosensors, semiconductors, polymers, carbon fibers, clusters and materials with nonlinear optical properties (Beck et al, 1992; Corma et al, 1997; Northcott et al, 2010).the base of the mesoporous molecular sieve is amorphous silica, which contains a considerable number of silanol groups and, due to its neutral character, exhibits limited activities in adsorption and catalysis (Qin et al, 2015). The incorporation of rare earth metals into mesoporous silicates showed an improvement in their thermal stability and structural properties, such as pore volume and surface area, compared with that of pure MCM-41 (Chien et al, 2005).
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