0000000000420119
AUTHOR
M. Teresa Portilla
Non-oxidative dehydroaromatization of methane:an effective reaction regeneration cyclic operation for catalyst life extension
[EN] Non-oxidative methane aromatization is an attractive direct route for producing higher hydrocarbons. It is highly selective to benzene despite the low conversion due to thermodynamic limitations, and Mo/H-ZSM-5, the first catalyst proposed for this reaction, is still considered as one of the most adequate. The major problem of this process is the severe catalyst deactivation due to the rapid build-up of carbonaceous deposits on the catalysts. Here we present an effective regeneration procedure that extends the life of Mo/zeolite based catalysts by combining reaction periods of 1.5 h with 0.5 h regeneration steps in a continuous cyclic mode and methane activation after each regeneration…
A New Aluminosilicate Molecular Sieve with a System of Pores between Those of ZSM-5 and Beta Zeolite
[EN] A new aluminosilicate zeolite (ITQ-39) has been synthesized. This is an extensively faulted structure with very small domains that makes the structure elucidation very difficult. However, a combination of adsorption spectroscopy and reactivity studies with selected probe molecules suggests that the pore structure of ITQ-39 is related to that of Beta zeolite, with a three-directional channel system with large pores (12-MR), but with an effective pore diameter between those of Beta and ZSM-5, or a three-directional channel system with interconnected large (12-MR) and medium pores (10-MR). The pore topology of ITQ-39 is very attractive for catalysis and shows excellent results for the pre…
Structure-reactivity relationship for aromatics transalkylation and isomerization process with TNU-9, MCM-22 and ZSM-5 zeolites, and their industrial implications
[EN] TNU-9 is a medium pore zeolite with a complex tridimensional channel system. Its catalytic properties have been studied in some reactions that involve the BTX fraction, such as benzene and toluene alkylation with methanol, ethanol or isopropanol. These reactions use in practice medium pore zeolites such as ZSM-5 (MFI) or MCM-22 (MWW), and the selectivities obtained with TNU-9 are compared and analyzed from the point of view of the zeolite structure and pore topology, as well as from its possible industrial application. For benzene alkylation to give ethylbenzene (EB), TNU-9 is an active and selective catalyst with selectivities to EB much higher than ZSM-5 and close to those of the ind…
Influence of layer structure preservation on the catalytic properties of the pillared zeolite MCM-36
MCM-36 is a catalytically active material made by swelling and subsequent pillaring of a layered zeolite precursor, MCM-22(P). However, the swelling procedures lead to significant destruction of layer structure and alteration of framework silicon/aluminum (Si/Al) ratio, which are likely to influence the acidity and catalytic activity of the final materials. We report a milder swelling and pillaring process to prevent such structural destruction. The resulting pillared materials show higher crystallinity and improved retention of the zeolitic layer structure when compared to the ones prepared by the previously reported methods involving more aggressive treatments. Implications of such struct…