One-pot conversion of glycerol to glycerol carbonate with NaAlO2-promoted hydrotalcite catalysts

Sodium aluminates supported on hydrotalcite are highly advantageous basic heterogeneous catalysts with strong basicity and interesting texture. We demonstrate that even if the texture of the hydrotalcite is strongly affected by the incorporation of NaAlO2, a good dispersion of the latter can be obtained, which appears to have a great impact on the catalytic conversion of glycerol to glycidol. This method should also allow us to further fine tune the basic strength by controlling SA amount for better catalytic activity in various base catalyzed biomass conversion reactions

New mixed oxides catalysts obtained by non-hydrolytic sol-gel investigated for biobased compounds conversion

Porous binary and ternary mixed oxides combining silica with Nb, Ta, Zr, W and Ti oxides with high specific surface areas and well-controlled compositions have been synthesized via the innovative NHSG technique4. These solids display acidic and basic properties, with mostly weak and medium strength Brönsted and Lewis acid sites. They are good candidates for the use in catalysis to transform some interesting biobased compounds particularly in gas phase. The study will be pursued by characterizing more precisely the materials by TOF-SIMS, MET-EDX, CDCl3-FTIR, chemisorbtion of CO and CO2, CO2-TPD and comparing them to model acidic and basic material (SiO2-SO3H, Silica alumina, MCM-41, SBA-15, Hydrotalcite, MgO). Moreover, further mixed oxides formulations are to be investigated in order to develop innovative catalytic materials and study the potential synergies generated in highly homogeneous ternary mixed oxides

Sol-gel routes to Ti-SiO2 epoxidation catalysts with tailored properties

The simultaneous control over texture and active site speciation is an important challenge in catalysis. The titanosilicalite-1 (TS-1) zeolite is a good illustration. This microporous crystalline material shows very high Ti dispersion and high performance e.g. in olefin epoxidation. However, its use in industrial applications is limited to lower olefins as the microporosity strongly hampers the diffusion of the reactants and products in and out the pores. Besides, the framework Ti content is limited to 2.5 mol. %. There are therefore strong incentives to find new titanosilicate catalysts, combining large pores and high Ti loading and dispersion, in order to extend the versatility of epoxidation catalysts to larger olefins (e.g. cyclohexene). However, these solids are often amorphous, bringing an additional challenge in order to stabilize the active species in the presence of water. Also, the catalysts are often obtained in the form of small powders, requiring further steps to shape the materials before they could be used in flow processes. Herein, we present three examples of sol-gel strategies which successfully address the above-mentioned challenges