Zouhaier Ksibi

Preparation of ruthenium supported catalysts for wet air oxidation of p-hydroxybenzoic acid

ABSTRACT Ru/TiO 2 and Ru/ZrO 2 catalysts were prepared by incipient-wetness method of sol-gel supports. They were characterized by means of nitrogen adsorption-desorption, X-ray diffraction (XRD) and transmission electron microscopy (TEM). Catalytic properties of the samples were determined in the wet air oxidation of p-hydroxybenzoic acid chosen as a model compound of olive oil wastewaters. The effect of the acid used for the preparation of aerogel support, the influence of the ruthenium salt used as the metal precursor (nitrosyl nitrate or acetylacetonate) and the nature of the support (TiO 2 or ZrO 2 ) were investigated. The results showed that the use of nitric acid for the synthesis of the support and Ru(NO)(NO 3 ) 3 leads to the more efficient catalyst. Furthermore, it was observed that the ZrO 2 support leads to a better p-hydroxybenzoic acid conversion than the TiO 2 one. No leaching of Ru, Ti or Zr was detected by inductive coupled plasma (ICP) analysis.

Physicochemical and catalytic properties of over- and low-exchanged Mo‒ZSM-5 ammoxidation catalysts

A series of Mo/ZSM-5 catalysts prepared by solid-state ion exchange at different Mo/Al molar ratios were characterized and tested in ethane and ethylene ammoxidation into acetonitrile. It has been concluded that the low-exchanged solid (Mo/Al = 0.2) stabilized MoO3, [Mo2O7]2− and [Mo7O24]6− species. However, besides these species, the solids prepared at Mo/Al = 0.5 and 1.5 stabilized [MoO4]2−. Nevertheless, only MoO3 and [Mo2O7]2− species were stabilized at Mo/Al = 1. The study performed by diffuse reflectance spectroscopy allowed the determination of the molar fraction relative to each Mo specie and, therefore, the calculation of the turnover frequency values. The catalytic activities of the various solids have been classified by taking into consideration the inefficiency of Al2(MoO3)4 phase, which inhibits the diffusion of reactants molecules towards the active sites, and amorphous MoO3 which catalyzes the undesired hydrocarbons’ combustion. However, [MoO4]2‒ species are efficient in the oxidative dehydrogenation of C2H6 into C2H4, while dimeric species catalyze the ammoxidation.

Catalytic Wet Air Oxidation of Parahydroxybenzoic Acid by Catalysts Based on Zirconia

Wet air oxidation (WAO) is an interesting treatment of toxic and nonbiodegradable wastewater such as phenolic products, which are at the same time too dilute to be incinerated and highly concentrated for a biological treatment.

3rd Workshop of the Euro-Mediterranean Consortium of Higher Education and Industrial Institutions: Freshwater and Climate Change

The Euro-Mediterranean Consortium of Institutes of Higher Education and Industry (C3ESI) is made up of universities and colleges of engineering.