Pure silica MCM-48 and MCM-41 materials were prepared using GEMINI surfactants, with the general formula [C n H2 n +1N+(CH3)2−(CH2) s −N+(CH3)2C m H2 m +1].2Br-, abbreviated as GEM n-s-m. The alkyl chain length (n,m) determines the pore size, whereas the length of the spacer (s) influences the crystallographic phase formed. A spacer length of 10−12 C yields the cubic MCM-48; smaller spacers favor the hexagonal MCM-41 phase. A hydrothermal treatment is introduced as an intermediate synthesis step, which strongly improves the quality and stability of the calcined materials. The hydrothermal treatment reduces the synthesis time of high-quality MCM-48 to only 2 days. Both GEM 18-12-18 and GEM 16-12-16 yield excellent MCM-48, with a surface area in the range 1200−1600 m2/g and pore volumes exceeding 1.2 mL/g. The maxima of the very narrow pore size distributions are found at r p = 13.1 and 12.2 Å, respectively. The GEM 16-10-16 and GEM 18-10-18 surfactants also yield MCM-48, but the quality of these materials is lower. The GEM 16-8-16 finally yields MCM-41.

TiO x -VO x mixed oxides supported SBA-15 catalysts were prepared in a very controlled way by the designed dispersion method (MDD) using acetylacetonate complexes. The Ti and V active centers are generated by the MDD of the TiO(acac) 2 and VO(acac) 2 . The process consists of the adsorption and subsequent thermolysis of the Ti-V complexes. A careful selection of synthesis conditions allows us to modify the mutual interaction of the Ti and V centers and the interaction of the active centers with the silica support. The decomposition of the anchored complexes and the conversion of the physisorbed species toward covalently bonded TiO x -VO x surface groups have been studied by using a home-built in-situ IR transmission cell. IR seems to be the most suitable technique to follow the calcination process that is required to understand the reaction mechanism. During the thermal conversion, the Ti-V/acac precursor is converted toward supported mixed oxide. Additional characterization was done by FTIR-PAS, TGA, chemical analysis, as well as XRD, FT-Raman, and N 2 adsorption measurements.

Hydrothermal stability of SAPO-34 is greatly improved by the treatment of the acidic form of the SAPO-34 with NH3.

SAPO-34 has been modified by silanation and disilanation reactions. The acidic properties of these modified SAPOs have been characterized by IR measurements. The bands of the bridging hydroxyls at 3600 and 3625 cm -1 show a gradual decrease in intensity with increasing silane or disilane loading. The band intensity of the P-OH group at 3675 cm -1 remains unaffected. The silanation process can be monitored (i) spectroscopically through the characteristic IR band of Si-H at 2250 cm -1 and (ii) analytically by the changes in the H 2 /SiH 4 ratio during the modification. CD 3 CN has been used as an IR spectroscopic probe to elucidate the changes in Brønsted and Lewis acidity of the modified SAPO-34. The intensity of the CtN absorption band at 2320 cm -1 , which is attributed to CD 3 CN adsorbed on Lewis acid sites, increases relative to the band at 2290 cm -1 (Brønsted acidity). This indicates that Brønsted acid sites are irreversibly transformed into Lewis acid sites after silanation reactions on the SAPO-34. 1 H and 29 Si MAS NMR confirm that the silanes react with the Brønsted acid sites resulting in silicon incorporation and silanol formation. Methanol adsorption capacity measurements indicate that silanation and disilanation reactions cause a significant reduction of the void volume of the SAPO-34 cages without creating diffusion limitations. The ethylene/ethane and propylene/ propane selectivity ratios in the MTO reaction (methanol-to-olefins) increase as a function of the (di)silane loading, while the amount of coke on the SAPO-34 decreases linearly with increasing (di)silane loading.

The acidic properties of hexagonal mesoporous aluminosilicates synthesized via a new successful short time synthesis route using leached saponite and a low concentration of surfactant are thoroughly investigated. The resulting aluminosilicate mesoporous materials with high Si/Al ratios of around 11 have a maximal surface area of 1130 m2/g, a pore volume of 0.92 cm3/g, and a narrow pore size distribution at around 3 nm. The replacement of the sodium ions, present as counterions in the synthesized aluminosilicates, with protons imparts useful catalytic acidity. This acidity is extensively studied with FTIR spectroscopy after adsorption of ammonia and cyclohexylamine, while deuterated acetonitrile differentiates between Brønsted and Lewis acidity. 27Al NMR spectroscopy determined the coordination of the aluminum in the FSM materials. Simultaneously the effect of an additional Al incorporation, utilizing sodium aluminate, aluminum nitrate, and aluminum isopropoxide is studied. From an acidic point of view, the incorporation with Al(NO3)3 appears to be the most optimal, as the sample has a very high amount of acid sites (1.3 mmol/g). Investigating the nature of the acid sites it is found that in all samples except the one incorporated with Al(NO3)3, more Brønsted than Lewis sites are present, both sites being quite acidic as they resist desorption temperatures up to 300 °C. Probing the coordination and location of the Al atoms, all the catalysts appeared to have mostly tetrahedral aluminum, up to 95% of the total Al amount for the proton exchanged Al(NO3)3 incorporated sample.

Hexagonal mesoporous aluminosilicates are prepared by a new short time synthesis route using leached saponite and a low concentration of surfactant. The samples are characterized by powder XRD and EPMA. The materials with Si/Al ratios of around 11 have a maximal surface area of 1130 m 2 /g, a pore volume of 0.92 cm 3 /g, and a narrow pore size distribution at around 3 nm. Replacement of the Na + ions present in the synthesized aluminosilicates by protons imparts useful catalytic acidity. The acidity of the materials is extensively studied by FTIR and 27 Al NMR spectroscopy. -(LINSSEN*, T.; MEES, F.; CASSIERS, K.; COOL, P.; WHITTAKER, A.; VANSANT, E. F.; J.