Joana M. F. B. Aquino

Synthesis, characterization and catalytic application of cerium-modified MCM-41

The nanostructured CeMCM-41 material was synthesized by the hydrothermal method, using cethyltrimethylammonium bromide as template. The sample was characterized by X-ray diffraction, energy-disperse X-ray, thermogravimetry, nitrogen adsorption isotherm and pore size distribution. The specific surface area of CeMCM-41 was equivalent to 850 m 2 g -1 , with the pore width and mesopore volume of 3.8 nm and 0.8 cm 3 g -1 , respectively. To evaluate the catalytic performance of the CeMCM-41, a mass of ca. 0.1 g was heated from room temperature up to 723 K at heating hate of 10°C min -1 using oxygen flowing at 50 ml min -1 . The CeMCM-41 was tested as catalyst for n-heptane oxidation, in a fixed-bed continuous-flow reactor, at 723 K and F/W ratio (molar flow of reactant per mass of catalyst) of 0.4-0.6 g h mol -1 . The obtained products were analyzed in a gas chromatograph coupled to a mass spectrometer. The GC-MS analysis revealed that the main oxidation products obtained were typically CO and CO 2 , with 12% of hydrocarbon conversion.

Synthesis and characterization of sulfate-supported MCM-41 material ☆

Abstract The MCM-41 was synthesized by the hydrothermal method using silica, sodium hydroxide, cethyltrimethylamonium bromide (CTMABr) as template, and distilled water as solvent. The sample was characterized by BET surface area, X-ray diffraction, infrared spectroscopy and thermogravimetry. The sulfate containing MCM-41 was prepared by the controlled impregnation of MCM-41 with 0.5 N sulfuric acid. The acid properties, as studied from n -butylamine adsorption and thermogravimetry, showed that MCM-41 has no considerable acidity, whereas the SO 4 2− /MCM-41 presents acid sites. The material was used as catalyst in the isopropanol dehydration, in a fixed bed continuous flow reactor. The sulfate containing MCM-41 present high activity to isopropanol dehydration at 473 K, and W / F of 4.1 g s/mol, with selectivity to propene.

Hydrodesulfurization of thiophene over coblat and molybdenum sulfides supported on MCM-41 materials

In this work was studied the potential application of molybdenum suphides supported on SiMCM-41 and A1MCM-41 materials in the thiophene hydrodesulfurization. The SiMCM-41 and AIMCM-41 materials were synthesized by hydrothermal method using cethyltrimethylammonium bromide as template. The deposition of the active HDS species was performed by solvent excess impregnation of ammonium tetrathiomolybdate salt over the supports followed by calcination. Cobalt was used as promoter in order to obtain a Co/(Co+Mo) atomic ratio of 0.3. The materials presented activity in thiophene HDS.