Préparation et caractérisation d'hydrotalcites dopées par des terres rares : applications aux réactions de condensations aldoliques

Preparation and Characterization of Rare Earth Elements Modified Hydrotalcites and Their Catalytic Performances for Aldol Condensation Reactions

• Auteur / Autrice : Zheng Wang
• Direction : Nadine Essayem, Guanzhong Lu
• Type : Thèse de doctorat
• Discipline(s) : Chimie
• Date : Soutenance le 02/07/2015
• Etablissement(s) : Lyon 1 en cotutelle avec East China University of science and technology (Shanghai, Chine ; 1953-....)
• Ecole(s) doctorale(s) : École doctorale de Chimie (Lyon ; 1995-....)
• Partenaire(s) de recherche : Laboratoire : Institut de Recherches sur la Catalyse et l'Environnement de Lyon (Villeurbanne, Rhône ; 2007-....)
• Jury : Président / Présidente : Pascal Fongarland
• Jury : Examinateurs / Examinatrices : Nadine Essayem, Guanzhong Lu, Yanqin Wang
• Jury : Rapporteurs / Rapporteuses : Jean-Marc Clacens, Heyong He

Mots clés

Mots clés contrôlés

Catalyseurs

Réhydratation

Métaux des terres rares

Hydrotalcite

Mots clés libres

Hydrotalcite

Éléments des terres rares

Réaction de condensation aldolique

Réhydratation

Catalyseurs à base solide

Hydrotalcite

Rare earth elements

Aldol condensation reaction

Rehydration

Solid base catalysts

Résumé

Résumé anglais uniquement

Nowadays there is an urgent need to develop green chemical processes, where the use and generation of toxic substances can be avoided. Indeed, the lignocellulose feedstock destructuration will produce aqueous solutions of ketones or aldehydes and it would be an important breakthrough to develop solid base catalysts capable to promote the aldol condensation. In this thesis, the main results are shown as follows: Magnesium and rare earth mixed oxides (MgReOx), rare earth modified MgAl-HT catalyst were prepared and were evaluated in liquid phase acetone self-aldolization. Rare earth modified MgAl catalysts show enhanced catalystic activity than MgReOx catalysts. Rehydrated MgAl-HT modified with Y and La, also present a higher water tolerance for aldol reaction. The same catalysts were also applied to acetone gas phase self-condensation reaction. At low temperature, the mesityl oxide is the main product for all the catalysts. At high temperatures, deactivation rate is lowered over MgAlCe(Y)O catalysts, and the presence of trimers (selectivity of IP over 50%) is much more noticeable for the MgAlY(Ce)O catalysts. A good balance between basicity and acidity is proposed to increase the selectivity of IP. In the cross condensation of citral and acetone, the citral conversion and pseudoionone yield were significantly enhanced over Mg3AlaY1-aOx catalysts. A general mechanism of reaction was proposed that the Y modified MgAl mixed oxides undergoes the rehydration by the water formed during the reaction, and the rehydrated catalysts with active Brønsted basic sites are responsible for the significantly improvement of catalytic activity