A TIME DEPENDENT STUDY FOR THE FORMATION OF ULTRASMALL Cs-AlMCM-41 HOLLOW NANOSPHERES

Abdullahi Haruna,Kabo S Kamaluddeen,Sani Sadiq

doi:10.33003/fjs-2021-0501-575

Abdullahi Haruna, Kabo S Kamaluddeen + Show 1 more

Open Access

https://doi.org/10.33003/fjs-2021-0501-575

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Abstract

Monitoring of the formation of ultrasmall Cs-AlMCM-41 nanospheres under hydrothermal condition has been performed. It showed that when the CTABr surfactant, silica and alumina were mixed, homogenization of raw materials was first taking place, where CTABr molecules first interacted with the inorganic species via self-assembly into helical rod-like micelles. Hydrolysis, condensation and polymerization of silica and alumina precursors were then initiated. In addition, the Cs+ cation also participated during the formation of MCM-41 structure where it counterbalanced the negative charge of the aluminosilicate surface. After 14 h, the aluminosilicate oligomers were produced and fully enclosed the spherical micelles. Further increasing the hydrothermal treatment to 24 h onwards, polycondensation silanol siloxane would take place leading to the emergence of well-defined and highly ordered MCM-41 structure. This study came up with a clear picture on the formation of Cs-AlMCM-41 hollow nanospheres in cationic-surfactant-templated. This suggested that similar studies for other mesoporous materials such as MCM-48 and MCM-50 under different conditions and approaches could also be explored

Highlights

Mesoporous materials are an important class of porous solids having pore sizes from 2 to 50 nm (Kresge et al 1992)
Ultrasmall CsMCM-41 with hollow nanospheres (CsM-30) with a SiO2/Al2O3 ratio = 30 were synthesized as follows: Clear Solution 1 was first prepared by dissolving CTABr
The results demonstrated that when both surfactant, silica and alumina solutions were mixed under moderate stirring for 15 min, the process comprises homogenization of raw materials, where CTAB surfactants were first self-assembled into helical rod-like micelles, followed by hydrolysis, condensation and polymerization of silica and alumina precursors

Summary

Introduction

Mesoporous materials are an important class of porous solids having pore sizes from 2 to 50 nm (Kresge et al 1992). Since the first discovery of MCM-41 in 1992, a number of patents and publications on the synthesis of this mesomaterial and other new mesoporous silica (e.g. SBA, FDU, FSM, HMS, and MSU) have been reported. The chemical interaction and selfassembly mechanism between the surfactants and inorganic precursors have been discussed (Inagaki et al, 1993; Tanev and Pinnavaia, 1995; Bagshaw et al 1995; Zhao et al, 1998; Liu et al 2002). Nanospheres was reported which was investigated by complementary analyses involving advanced characterization techniques such as XRD, TEM, FTIR, N2 sorption, TGA/DTG and XRF. The study was performed by interrupting the formation at various intervals and the solids were systematically characterized until well-ordered ultrasamall CsAlMCM-41 hollow nanospheres was formed

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