Synthesis of MCM-41 nanomaterial from Algerian bentonite: influence of synthesis pH

Mesoporous materials of the MCM-41 type were synthesized from Algerian bentonite as an aluminosilicate source without the addition of pure silica and aluminum reagents. The samples were synthesized under hydrothermal condition using cetyltrimithylammonium bromide (CTAB) as surfactant. The influence of initial synthesis pH on the material properties of as-synthesis MCM-41 samples was studied at different temperatures of crystallization. The samples were characterized using several techniques e.g. X-ray diffraction (XRD), N2 adsorption-desorption and transmission electron microscope (TEM). The experimental results showed that bentonite can be used as an aluminosilicate source for the synthesis of Al-MCM-41. By decreasing the synthesis temperature of crystallization, it is necessary to decrease the synthesis pH value to form the best ordered hexagonal phase and eliminate the lamellar phase.Keywords: bentonite; alkaline fusion; pH; Al-MCM-4

Optimised synthesis and characterisation of 1-adamantyltrimethylphosphonium iodide

This work was financially supported by the EPSRC (grant numbers EP/L505079/1 and EP/M506631/1) and COST action SM1302 SIPs. The authors thank the University of St Andrews NMR Service and the EPSRC UK National Mass Spectrometry Facility at Swansea University (NMSF).A synthetic route to multigram quantities of 1-adamantyltrimethylphosphonium iodide is reported. The synthesis starts from the commercially available precursor 1-adamantyl bromide and was optimised with respect to yield and ease of purification. The title compound is of interest to zeolite chemists as a potent organic structure-directing agent. Full spectroscopic characterisation data of all isolated intermediates and single crystal X-ray diffraction data of AdP(O)Cl2, [AdPMe2H]I and [AdPMe3]I (Ad = 1-adamantyl) are reported.PostprintPeer reviewe

Échange ionique dans les zéolites par la méthode sèche. Mise en évidence de l'influence de quelques paramètres

There is only very little data on solid-state ion exchange in zeolites reported in the literature so far. These studies concern principally alkaline and alkaline earth metals. We can obtain, high exchanged zeolites with transition metals, between 30 and 50% exchange. It was shown that, both low temperature and high-temperature exchange processes occured. It was the aim of the present study to elucidate whether in principle, higher degrees of exchange can be obtained by solid-state reaction than by conventional ion exchange in salt solution, and result in catalysts more active. We also study, the influence of some parameters, such as, temperature, inert gas flow, time of exchange and the proportion of salt, on the degree of exchange. Chlorides of cobalt and iron were tested

L'évolution des propriétés catalytiques de silices mésoporeuses dopées au titane en fonction du greffage hydrophobe en surface des matériaux

Depuis la découverte des matériaux mésoporeux par la firme Mobil Oil en 1992, beaucoup d'études ont été réalisées sur la modification des propriétés physico-chimiques pour améliorer l'activité et la sélectivité catalytique de la surface de ces matériaux. Dans cette étude, on a greffé un organosilane de type triméthylchlorosilane (TMCS) sur la surface de ces matériaux mésoporeux de type MCM-41, MCM-48 et FSM-16 purement silicique et autres dopés au titane par post-synthèse. Ce traitement a permis d'améliorer le rendement des produits d'oxydation du cyclohexène en présence de H2O2. L'effet du greffage sur la structure et la texture de ces matériaux a été examiné par (DRX, BET et IR). Les produits de la réaction sont analysés par GC/MAS

β-diketone functionalized SBA-15 and SBA-16 for rapid liquid–solid extraction of copper

International audienc

Influence of the particle size of Cu-ZSM-5 for the heterogeneous oxidation of bulky hydrocarbons

Diffusion limitations inducing pores blocking is a key para- meter when using heterogeneous catalysts. The aim of this work is to study the influence of the particle size and therefore, the external surface extent, on catalytic properties of ZSM-5 crystals. Nanocrystals or microcrystals of Cu-ZSM-5 were prepared and characterized. The key difference between these catalysts is the extent of external active surface, favouring the nanocrystal form of ZSM-5. Both materials were further employed for the catalytic oxidation of various substrates differing by their size. Oxidation of indane, tetralin, propyl and octylbenzene was successfully performed when using both catalysts. However, a clear enhancement was observed when the nanocrystal form of Cu-ZSM-5 was used. The different efficiency of both catalysts was discussed in terms of external active surface and diffusion limitations

Synthesis of MCM-41 nanomaterial from Algerian bentonite: influence of synthesis pH

International audienceMesoporous materials of the MCM-41 type were synthesized from Algerian bentonite as an aluminosilicate source without the addition of pure silica and aluminum reagents. The samples were synthesized under hydrothermal condition using cetyltrimithylammonium bromide (CTAB) as surfactant. The influence of initial synthesis pH on the material properties of as-synthesis MCM-41 samples was studied at different temperatures of crystallization. The samples were characterized using several techniques e. g. X-ray diffraction (XRD), N-2 adsorption-desorption and transmission electron microscope (TEM). The experimental results showed that bentonite can be used as an aluminosilicate source for the synthesis of Al-MCM-41. By decreasing the synthesis temperature of crystallization, it is necessary to decrease the synthesis pH value to form the best ordered hexagonal phase and eliminate the lamellar phase