Effect of aluminium incorporation by the “pH-adjusting” method on the structural, acidic and catalytic properties of mesoporous SBA-15

Preferential carbon monoxide oxidation on Ag/Al-SBA-15 catalysts: Effect of the Si/Al ratio

“…In order to interpret the role of the "pH adjusting" step, the reference Al-SBA-15 (5) sample prepared without the ''pH adjusting'' step shows a final Si/Al ratio of 109. This result confirms the low efficiency of ''one-pot synthesis'' in strongly acidic media to introduce Al in the silica framework of SBA-15, which is consistent with the reports in literatures [25,26]. Table 1.…”

“…As known in Fig. 4, the 27 Al MAS NMR spectra for the Al-SBA-15 materials with different Si/Al ratios are different to those previously reported for Al doped mesoporous silica materials [25,26]. When a small number of Al is added into the SBA-15 support, only one peak in the 27 …”

“…Many studies have demonstrated that preparation condition and doping of heteroatoms into the framework both cause the expansion of unit cell [25][26][27]. It is ascribed to the ionic radius of Al 3+ (0.039 nm) is larger than that of Si 4+ (0.026 nm).…”

Study of catalytic activity at the Ag/Al-SBA-15 catalysts for CO oxidation and selective CO oxidation

“…It was found that the octahedrally coordinated extra-framework Al connected to the framework via oxygen atoms suppressed the formation of H-bonded SiOH groups, resulting in the formation of highly dispersed Ag nanoparticles with high catalytic activity. Combined with previous studies [4,26,30,31], it was found that the alumina sources strongly affected the morphology and microstructure of SBA-15, consequently affecting the structure and activity of Ag catalysts. Our previous studies showed that XRD and TEM results of supported Ag catalysts with different Si/Al ratios were obviously different by using different alumina sources [4,26].…”

Continuous-Flow Hydroisomerization of C5–C7 Alkanes Using Mechanochemically Synthesized Supported Pt and Pd-SBA-15 Materials

“…SBA-15-type structures comprise a family of hexagonally ordered materials which emerged as an alternative to MCM-41 with thicker walls and improved stability as a catalyst or catalyst support even in high temperature reactions. A number of efforts have been devoted to develop various functional SBA-15 materials to overcome the inherently inert nature of their siliceous counterparts [2]. While the addition of acids including hydrofluoric (HF) or sulphuric acid increases acidity in SBA-15 materials, these mineral acids are also hazardous and synthesized materials have not been shown to be thermally stable [1].…”