Synthesis of [B,Al]-EWT-Type Zeolite and Its Catalytic Properties

EWT zeolite belongs to ultra-large pore zeolite with the 10MR and 21MR channels, which has good thermal stability, certain acid strength and good application prospects in petroleum refining and petrochemical reactions. However, EWT zeolite has fewer medium/strong acid sites, especially Brönsted acid sites, which makes it difficult to apply to acid-catalyzed reactions. The regulation of acid amount and distribution was achieved by boron and aluminum substitution into the siliceous framework of EWT. The physico-chemical properties of the samples were characterized by XRD, SEM, N₂ adsorption-desorption, XRF, ICP, Py-IR, NH₃-TPD and ¹¹B & ²⁷Al & ²⁹Si MAS NMR. The results show that quantities of boron and aluminum elements can occupy the framework of [B,Al]-EWT to increase the density of medium and strong acid centers, with more acidity and Brönsted acid centers than EWT zeolite. In the reaction of glycerol with cyclohexanone, the conversion of the sample (U-90-08-10/U-90-H-HCl) is significantly higher than that of the EWT sample, approaching or exceeding the Beta zeolite. A catalytic activity study revealed a direct correlation between the Brönsted acidic site concentration and the activity of the catalyst. The U-90-08-10-H catalyst was also considerably stable in the catalytic process. This work shows, for the first time, that extra-large pore zeolites can be used in industrial acid-catalytic conversion processes with excellent catalytic performance.

Conversion of methanol to hydrocarbons over H-MCM-22 zeolite: deactivation behaviours related to acid density and distribution

The deactivation of H-MCM-22 zeolites with different Si/Al ratios can be roughly divided into three stages: first the rapid deactivation of the supercages, the second reaction with slow coking and the deactivation stage with rapid coking mainly on the external pockets.

Boric acid treated HZSM-5 for improved catalyst activity in non-oxidative methane dehydroaromatization

The dehydroaromatization (DHA) reaction of methane under non-oxidative conditions is carried out over a molybdenum catalyst supported on HZSM-5 and boric acid (BA) treated HZSM-5 at 700 °C and atmospheric pressure.

Precise control of density and strength of acid sites of MFI-type zeolite nanoparticles via simultaneous isomorphous substitution by Al and Fe

The co-incorporation of Al and Fe at various relative ratios into the MFI-type zeolite framework enabled linear control of the density and strength of acid sites, and such well-tuned acidity led to a better catalyst lifetime.

Alkali metal ion exchanged ZSM-5 catalysts: on acidity and methanol-to-olefin performance

The acid site density and counter ion nature impact the proportion of alkene- and aromatic-based MTO reaction cycles.

Methane adsorption and methanol desorption of copper modified boron silicate

Boron silicate (BS) with a chabazite framework structure was synthesised using a direct route and rigorously characterized before it was ion-exchanged with copper to form Cu-BS. Employing in situ infrared spectroscopy, we show that Cu-BS is capable of oxidising methane to methoxy species and methanol interacts with the boron sites without deprotonation.

Boron silicate (BS) with a chabazite framework structure was synthesized and ion-exchanged with copper to form Cu-BS which was capable of oxidizing methane to methoxy species.

Insight into the effect of incorporation of boron into ZSM-11 on its catalytic performance for conversion of methanol to olefins

The MTO catalytic performance of ZSM-11 can be finely tuned by incorporating boron through regulation of aluminum location in the framework.

Highly stable boron-modified hierarchical nanocrystalline ZSM-5 zeolite for the methanol to propylene reaction

A highly stable MTP catalyst, boron-modified hierarchical nanocrystalline ZSM-5 zeolite, has been synthesized by a facile salt-aided seed-induced route. It exhibits a long lifetime (about 725 h) even at a high WHSV (4.0 h⁻¹).