Jean-Pierre Dath

Preparation of highly active gas oil HDS catalyst by modification of conventional oxidic precursor with 1,5-pentanediol

Abstract The performances of gasoil hydrodesulphurization catalysts are successfully improved by modification of CoMo/Al 2 O 3 oxidic precursor with 1,5-pentanediol. This organic agent retards the sulfidation of the supported metals, leading to a simultaneous sulfidation of both Co and Mo atoms, which induces a better decoration of MoS 2 slabs with smaller length.

Embryonic ZSM-5 zeolites: zeolitic materials with superior catalytic activity in 1,3,5-triisopropylbenzene dealkylation

Embryonic ZSM-5 zeolites are harvested from clear ZSM-5 precursor solutions after freeze-drying and calcination. These materials are microporous with pore sizes close to those of ZSM-5 zeolites. Due to their partially formed structure, embryonic zeolites do not display a long range order and are XRD amorphous. Their micropores are highly accessible, and resistive to high temperature treatments and the strength of their acid sites is comparable to zeolites. These characteristics give them superior catalytic performances in the conversion of a bulky model molecule, 1,3,5-triisopropylbenzene.

Revelation on the complex nature of mesoporous hierarchical FAU-Y zeolites

The texture of mesoporous FAU-Y (FAUmes) prepared by surfactant-templating in basic media is a subject of debate. It is proposed that mesoporous FAU-Y consists of: (1) ordered mesoporous zeolite networks formed by a surfactant-assisted zeolite rearrangement process involving local dissolution and reconstruction of the crystalline framework, and (2) ordered mesoporous amorphous phases as Al-MCM-41, which coexist with zeolite nanodomains obtained by a dissolution-reassembly process. By the present systematic study, performed with FAU-Y (Si/Al = 15) in the presence of octadecyltrimethylammonium bromide and 0 < NaOH/Si ratio < 0.25 at 115 °C for 20 h, we demonstrate that mesoporous FAU zeolites consist, in fact, of a complex family of materials with textural features strongly impacted by the experimental conditions. Two main families have been disclosed: (1) for 0.0625 < NaOH/Si < 0.10, FAUmes are ordered mesoporous materials with zeolite walls, which coexist with zeolite nanodomains (100-200 nm) and (2) for 0.125 < NaOH/Si < 0.25, FAUmes are ordered mesoporous materials with amorphous walls as Al-MCM-41, which coexist with zeolite nanodomains (5-100 nm). The zeolite nanodomains decrease in size with the increase of NaOH/Si ratio. Increasing NaOH/Si ratio leads to an increase of mesopore volume, while the total surface area remains constant, and to a decrease of strong acidity in line with the decrease of micropore volume. The ordered mesoporous materials with zeolite walls feature the highest acidity strength. The ordered mesoporous materials with amorphous walls present additional large pores (50-200 nm), which increase in size and amount with the increase of NaOH/Si ratio. This alkaline treatment of FAU-Y represents a way to obtain ordered mesoporous materials with zeolite walls with high mesopore volume for NaOH/Si = 0.10 and a new way to synthesize mesoporous Al-MCM-41 materials containing extralarge pores (50-200 nm) ideal for optimal diffusion (NaOH/Si = 0.25).