Helical Al- and Ce-MCM-41 materials as novel catalyst for acid and redox processes

[Display omitted] ► Synthesis of novel Al- and Ce-containing helicoidal mesoporous materials. ► Low metal containing materials helicoidally structured with catalytic properties. ► Highly active materials in the oxathioacetalisation of aldehydes and ketones and epoxidation of cyclohexene. Helical mesoporous silicas containing aluminium or cerium into their framework have been synthesized via hydrothermal method. The synthesized materials were extensively characterized to understand their physico–chemical properties in view of their future catalytic applications. Low-angle powder XRD patterns of calcined samples showed a hexagonally ordered mesopore structure. NMR spectra of aluminium materials exhibited two signals at 50 and 0ppm assigned to tetracoordinated and octahedrally coordinated Al3+. DR-UV–vis and XPS spectrum of cerium content materials show that cerium was incorporated as Ce3+ and Ce4+ into the helical mesoporous material. Materials with molar ratios Si/Al=95 and Si/Ce=500 were found to be catalytically active in acid (oxathioacetalisations and alkylations) or redox (epoxidation of cyclohexene) catalyzed processes, respectively.