Proiect Cercetare TE 105-2011

NEW STRATEGIES FOR THE SYNTHESIS OF FINE CHEMICALS BY CATALYTIC SELECTIVE OXIDATION

 

Autoritatea contractanta: Unitatea Executiva pentru Finantarea Invatamantului suprior, a Cercetarii, Dezvoltarii si Inovarii

Director proiect: Dr. Mihaela Florea

OBJECTIVES

The main driving force of this project is to establish new strategies for the development of new efficient catalysts for oxidation processes, with high efficiencies and in environmentally friendly conditions. The project will try to elaborate theoretical and practical concepts for oxidation reactions and to propose new effective catalysts. It will also look for the efficient methodologies of preparation of such catalysts. We consider that the project is in accord with the international research criteria and this proposal represents a landing of many branches of science for the identification of the best ways to reach this objective.

ABSTRACT

The problem of identifying new materials and with sustainability concepts, and lowering until stopping the pollution, was situated by the EU as a priority element on the criteria list which should be considered for financing the FP7 projects. That’s why identifying new technological solutions for the preparation of new materials for oxidation processes and fine chemistry, with high efficiencies and in environmentally friendly conditions, is of high importance and relevant in this competition context. The present project will follow two main research directions: 1) The development and optimization of the synthesis routes of vanadium based catalysts by using different synthetic methods. The incorporation of the third element (Fe or Ga) in the oxide structures will be done by using coprecipitation and impregnation. 2) The catalytic investigation in hydrocarbon oxidation and fine chemistry, more precisely of toluene, p-xylene and 2-methyl-1-naphthol or 2-methylnaphtalene. In order to establish the relation between the materials history and their catalytic performances, all materials will be fully characterised by using techniques such as: BET, XRD, TG-DSC, FTIR, TPR, UV-VIS, RAMAN and chimisorption measurements in situ condition, XPS, etc. The technological effect of such a study is immediate, since it allows establishing scientific criteria for elements selection for industrial catalysts preparation and the extensive approach of surface phenomena occurring on catalytic solids.

MILESTONES

- Preparation of new vanadium-aluminium mixed oxide catalytic systems, by varying different parameters

- Preparation of new vanadium-iron/gallium-aluminium catalytic systems, by varying different parameters

- Determination of the textural properties of the VAlO catalysts containing different V/Al ratio, different elements. 

- Determination of specific phase for each structure by X-ray diffraction.

- Identification of the new elements by chemical analysis, UV-VIS spectrometry, FTIR, XPS, RAMAN.

- Acid and basic properties investigation.

- Quantification of the adsorbed species.

- Determination of the catalytic site

- Identification of the optimal conditions for catalytic tests in order to obtain good activity and selectivity of these materials.

- Optimization of the reaction conditions in order to obtain the highest yields for the economic transfer.

- Identification of the optimal conditions for catalytic tests in order to obtain good activity and selectivity of these materials.

- Optimization of the reaction conditions in order to obtain the highest yields for the economic transfer.

TEAM MEMBERS

Mihaela Florea - director

Codruta Rotaru

Roxana Marin

Giorgiana Calman

Major Results

           The prepared mixed oxides exhibited type IV adsorbtion-desorbtion isotherms (mesoporous materials) and surface areas in the range 71 to 252 m2/g. The XRD patterns indicated an amorphous structure for the samples calcined until 500°C. After that a diffraction peak was observed at 2θ=25.06° and 27.48° corresponding to FeVO4. All Raman spectra revealed an intense band attributed to stretching frequency of V=O (at 950 cm-1). For the sample with higher loading of iron (Fe02) was observed a weak band assigned to asymmetric stretching vibration of V–O–Fe bond (641 cm-1), as well as bands at 346 cm-1 typical to those found in polymeric tetrahedral vanadates [VOx]n n−. The oxidation of PX with H2O2 over these catalysts yielded p-tolualdehyde (PTA) and p-toluic acid (TA) as major products (Figure 1). As a general tendency, the selectivity to PTA increases with the quantity of Fe, achieving a maximum of 68% for PTA in presence of Fe02. Also, TPA selectivity achieved a maximum of 15% at the highest iron loading.

 The results of this study reveal the possibility to develop a catalytic heterogeneous system for the synthesis of terephthalic acid using a vanadium based catalyst doped with iron. This study revealed that the transformation of p-xylene is favored by the presence of [VOx]n species. An optimal molar ratio of V/Fe of 1.25 was determined. It corresponded to the highest selectivity to TPA, i.e. 15%.

Also, the results obtained through this project indicate the possibility to develop a catalytic competitive system for the synthesis of vitamin K3, via selective oxidation on mesostructured V2O5-Al2O3 catalysts.  The transformation of 2-MN is favoured by the presence of decavanadate species, with an optimal V/Al ratio of 0.7.  An important aspect of the reaction is that the amorphous phase of the catalyst is more active than the crystalline one, enhancing the formation of vitamin K3. The best reaction conditions were 80˚C, substrate to oxidant agent ratio of 1:5, and acetonitrile as solvent. These also corresponded to the highest selectivity to vitamin K3, i.e. 54% at 73 % conversion of 2-MN.

 

 

 

 

 

 

 

Pagină actualizată la 24 Noiembrie 2014.