Poster

CO2 forum, 3rd edition
11
mai
/
2014, Poster

Petitjean Hugo : Varying morphologies of zirconia catalysts for structure-activity relationships in dimethyl carbonate synthesis

Aude Rosticher, Françoise Quignard, Hugo Petitjean, Nathalie Tanchoux, and Didier Tichit

 Institut Charles Gerhardt, UMR 5253 CNRS/ENSCM/UM2/UM1, Matériaux Avancés pour la Catalyse et la Santé

Ecole Nationale Supérieure de Chimie, 8 rue de l’Ecole Normale, 34296 Montpellier Cedex 5, France

Corresponding autor e-mail: aude.rosticher@enscm.fr

 

Using CO2 as a raw material to synthesize chemical compounds attracts attention from policy-makers and chemists. Indeed, the greenhouse gas CO2 is a C1 building block with many advantages: non-toxic, abundant, cheap and renewable [1]. However, CO2 has a critical disadvantage: it is very stable. CO2 conversion requires to find how activate CO2 efficiently.

CO2 could be elegantly activated through heterogeneous catalysis of nucleophilic addition of alcohols. This reaction gives dialkylcarbonates, which can be used as alkylating agents, diesel fuel additives and non-aqueous electrolytes. Industrially however, dialkylcarbonates are not produced through that nucleophilic addition of alcohols to CO2 because of two main drawbacks: the synthesis yields are limited by hydrolysis of the product and the reaction is too slow for a continuous process to be developed.

In this project, we focus on understanding the kinetics of the reaction. The catalytic mechanism has been studied by Tomishige et al. [2] and then by Jung and Bell [3], but it is still unclear. Our strategy is based on building structure-activity relationships with a model system: zirconia-catalyzed synthesis of dimethylcarbonate (Equation).

                              Equation

This poster presents the syntheses of the zirconia catalysts with various morphologies. We synthesized zirconia samples through various methods to obtain catalysts with a wide range of morphologies and catalytic activities, which is required for structure-activity relationships to be drawn. The variety of surface states is characterized with spectroscopic and reactive probing: usual post-synthesis techniques (XRD, physisorption, thermal analysis), spectroscopies probing the surface state (IR, NMR) and measurements of catalytic performances with gas chromatography.

We synthesized zirconia samples with two methods. The first method is the synthesis from metallic alginate gels. Alginate is a natural polymer with carboxylate groups available for metal coordination. Hydrogels are formed by coordination of zirconyl cations with carboxylate and then convert into alcogels by water-ethanol exchange. After drying of the gel (under vacuum or supercritical CO2), the matrix is decomposed under air flow. The second method is the classical precipitation route of zirconium hydroxide in aqueous media.

2014 - Petitjean Hugo - varying morphologies of zirconia catalysts_schema

Figure 1.  Aerogels formed with sodium alginate and ZrOCl2

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References:

  1. T. Sakakura, J.-C. Choi, H. Yasuda, Chem. Rev. 107 (2007) 2365-2387.
  2. K. Tomishige, Y. Ikeda, T. Sakaihori, K. Fujimoto, Journal of Catalysis 192 (2000) 355-362.
  3. K. T. Jung, A. T. Bell, Journal of Catalysis 204 (2001) 339-347.