Hydrophobic zeolites for biofuel upgrading reactions at the liquid-liquid interface in water/oil emulsions

Development of surface-modified fuajasite that stabilizes water/oil emulsions and catalyzes the alkylation of (organic-soluble) phenolics with (aqueous-soluble) alcohols in liquid biphasic systems. This system is a close approximation of what could be the best strategy to undergo reactions with the compounds present in the bio oil and get molecules with carbon length in the range of transportation fuels.

HRTEM and SEM demonstrate that the crystalline structure of the functionalized zeolite remains unchanged after reaction, while that of the hydrophilic zeolite is greatly affected. The HRTEM of the used OTS functionalized zeolite clearly shows that the ordered patterns of the microporous structure of the zeolite remain practically identical to those of the zeolite before reaction. By contrast, in the untreated zeolite they disappear after reaction.

SEM images indicate that while the external surface of the zeolite particles does not exhibit a significant change in texture after reaction, a significantly rougher surface is observed on the untreated zeolite after reaction in the hot liquid water.

Conversion of m-cresol and concentrations of m-cresol and alkylation products after the reaction of m-cresol and isopropanol at 200 °C and 700 psig over  OTS  functionalized HY zeolite (Si/Al molar ratio: 30).

The hydrophobic zeolite shows a continuous increase in the m-cresol conversion, in contrast hydrophilic catalyst is completely deactivated after 3 h of reaction.

The OTS functionalized zeolite is seen to retain a large fraction of its original activity (~ 85%) after regeneration and reuse, but the untreated zeolite loses completely its activity.


Surface modification of the HY stabilizes the zeolite against losses of crystallinity, greatly enhances the catalytic activity, regenerability, and reusability of solid catalysts in biphasic emulsion systems and protects it against leaching and destruction of its structure while keeping its active sites (in this case H+) inside practically unaltered.

The role of the hydrophobic barrier is to prevent the contact of the zeolite with the liquid water, avoiding the extensive hydrolysis accelerated by solvation and rapid ion mobility, which readily occurs with a conventional hydrophilic zeolite.