Direct synthesis of Cu–SBA-16 by internal pH-modification method and its performance for adsorption of dibenzothiophene

Copper-containing SBA-16 (with Si/Cu molar ratios 22, 43 and 61) has been synthesized by one step novel “internal pH-modification method” using hexamethylenetetramine (HMTA) as complexing agent and internal pH-modifier. HMTA plays a critical role in material synthesis; it releases NH3 during hydrothermal treatment to increase the internal pH of the gel that results in introduction of more amount of copper into silica framework. The synthesized material has been characterized by XRF, XRD, HRTEM, N2 adsorption/desorption, SEM, FT-IR, diffuse reflectance UV–visible spectroscopy and 29Si MAS NMR spectroscopy. The characterization results reveal that the synthesized materials possess ordered cubic mesoporous structure up to Si/Cu molar ratio 43; further increase in copper contents (Si/Cu = 22) lead to disordering of mesostructure. 29Si MAS NMR results indicate that copper has been successfully incorporated into silica framework. Owing to its high surface area (983–315 m2/g) and copper contents, the material was applied for the adsorption desulfurization of dibenzothiophene (DBT), wherein it exhibited good performance and reduced the sulfur contents of 40 mL of model oil with 550 ppm of sulfur (DBT) to a level of less than 1 ppm.