Mesoporous silica-aluminas

Aldol condensation reactions have also been conducted. A good example is provided by Climent et al. (1998) for making a-n-amyl cinnamaldehyde (Jasmin aldehyde) by condensing benzaldehyde with n-heptaldehyde, in the presence of mesoporous MCM-41 aluminosilicates. Mesoporous silica-aluminas with a narrow range of pore diameter such as MCM-41 also... 

Peratello, S., Molinari, M., Bellussi, G. and Perego, C. Olefins oligomerization thermodynamics and kinetics over a mesoporous silica-alumina. Catal. Today, 1999, 52, 271-277. 

Zeolites are combinations of A1203 and Si02 that are crystalline structures with precisely defined pore structures in the molecular size range (0.4—1.5 nm or 4-15 A). A related group of materials known as mesoporous silica-alumina has extended the range of pore sizes attainable in ordered Si02-Al203 supports to 4 nm (40 A). They are commonly used in the chemical and petroleum industry due to their surface acidity and ability to exclude molecules... 

Figure 3.3 FTIR spectra of gaseous CO and of CO adsorbed on silica-alumina, on silicalite (150K), on Au/Ce02 and on Pt-Pd alloy nanoparticles on MCM41 mesoporous silica-alumina.

Figure 3.20 FTIR spectra of a MCM-41 type mesoporous silica-alumina (a) after activation by outgassing at 773 K ...

The Surface Hydroxyl Croups of Microporous and Mesoporous Silica-Aluminas (SAs)... 

Figure 3.23 FTIR spectra of left, pyridine mesoporous silica-alumina (a) after activation adsorbed on H-MFI zeolite (a) in contact with by outgassing at 773 K (b) in contact with 1 Torr pyridine vapour and after outgassing 1 Torr pyridine vapour after outgassing at...

Influence of pH in mesoporous silica aluminas (MSA) synthesis C. Rizzo, A. Carati, C. Barabino, C. Perego and G. Bellussi... 

Catalyst. The catalyst studied in this work was a platinum (0.205% wt) supported on an amorphous mesoporous silica-alumina, MSA (Si02/Al203=100) extrud with 50% wt alumina. The synthesis of the catalyst and the metal deposition procedure were described in detail [9]. A used catalyst, prepared as the former and containing 0.186% wt of Pt, was studied after the hydroisomerization of an n-paraffin feed containing 10 ppm S. 

Several Pd-Pt (Pd Pt=4 l) catalysts for deep hydrodesulfurization (HDS) were prepared using a commercial amorphous silica-alumina (ASA), a novel mesoporous silica (MPS) and a novel mesoporous silica-alumina (MPSA) as carriers with dispersions of > 50%. They were characterized by various techniques and their performance in deep HDS of 4-ethyl, 6-methyl-dibenzothiophene measured at 633 K and 6.0 MPa in the presence of carbazole and H2S. The Pd-Pt catalysts showed good activity as compared to typical conventional HDS catalysts. Their activity decreased with a decreasing Al content in the support (thus support acidity) ASA > MPAS > MPS. Enhanced support acidity seems to favor the stabilization of the dispersed metal particles against sintering. 

Preparation and properties of Pt-Mo sulfide system supported on mesoporous silica-alumina... 

The preparation and properties of Mo and Pt-Mo systems (14 wt.% Mo, 0.5 wt.% Pt) on a mesoporous silica-alumina (MSA) were studied. The Mo catalysts were characterized by X-Ray diffraction, N2 adsorption-desorption and transmission electron microscopy (TEM). The sulfided catalysts were tested in the simultaneous HDS of thiophene and HDN of pyridine. Deposition of ammonium heptamolybdate on MSA followed by sulfidation at 400°C for 4 h gave a well dispersed M0S2 phase, as confirmed by TEM. The addition of about... 

When the sample is the powder zeolite mixed with silica-alumina (60% weight of zeolite, length 25 mm), the benzene concentration profiles (Figure 5-a) present an adsorption fi ont which lasts more than 30 min. On one hand, the intercrystallite diffiision rate is decreased by the presence of the mesoporous silica-alumina, on the other hand benzene also adsorbs on the silica-alumina. In the case of a compressed mixed sample (length 12 mm) the profiles are rectangular as... 

Amorphous micro/mesoporous silica-alumina gel having surface area of 500 m g with a molar ratio of SiOj/AlaOj >30 1... 

Moretti G, Dossi C, Fusi A, Recchia S, Psaro R (1999) A comparison between Cu-ZSM-5, Cu-S-1 and Cu-mesoporous-silica-alumina as catalysts for NO decomposition. Appl. Catal. B20 67-73... 

In the 1970s and 1980s already was evident how different are the spectroscopic features of silica-alumina and zeolites [211]. More recently, however, some papers reported the presence of very small bands near 3600 cm in the spectra of mesoporous silica-aluminas [212-214], supposed to be due to bridging zeolite-type sites. Theoretical works till the end of the 1990s modeled the active site for zeolites and silica-alumina in the same way, as Al-(OH)-Si bridging... 

---