Heterogeneous catalysis for utilization of renewable resources
Innovating catalyst design for the transformation of biomass into bio-based chemicals
The replacement of part of the fossil-based feedstock consumption by renewable raw-materials, in particular in fuels but also in the chemical industry, is a central strategy for resource and energy efficiency.
Conversion of CO2 into feedstocks for the fuel/chemical/process industry is a highly efficient way to rapidly introduce renewable energy in this value chain (e.g. increaseof bio-based feedstock, end-of-life feedstreams management, zero-waste processes, pollution control, etc.). Currently, the use of CO2 as chemical feedstock is limited to a few industrial processes— synthesis of urea and its derivatives, salicylic acid, and carbonates. This is primarily due to the thermodynamic stability of CO2, but there are many possibilities of reaction of CO2 and H2. The conversion of carbon dioxide to syngas, formic acid, methanol and dimethyl ether, hydrocarbons via Fischer–Tropsch synthesis and methane proceed effectively in this direction and fall into the two categories—fuels and chemicals. Other important applications of CO2 as C1 building block in organic synthesis includes the direct synthesis of dimetil carbonate, cyclic carbonates, urea and urethane derivatives, carboxylic acid, esters and lactones, and isocyanates. A very interesting approach is the substitution of CO by CO2 in carbonylation reactions by in situ formation of CO. The catalytic conversion of CO2 to CO via the reverse water gas shift (RWGS) reaction is the first step for the production of hydrocarbons via Fischer–Tropsch synthesis or for carbonylations using CO2. Due to the importance of this reaction from both fundamental and practical points of view, the design and characterization of RWGS catalysts have attracted considerable attention. Our main goal is to explore the unique properties of metal nanoparticles for the design of heterogeneous catalysts for the conversion of CO2 to CO (RWGS) and carbonylations into high value chemicals. Excellent results were obtained with Ni catalysts prepared by magnetron sputtering deposition (CO2 hydrogenation)
Conversion of carbohydrates and sugars into feedstock for the chemical industry is modest when considering their ready availability at low cost and the huge as yet unexploited potential. Efforts to boost the production of bio-based chemicals and to replace those derived from petrochemical sources certainly include the development of new catalytic processes. The chemistry of gold offers unique opportunities in catalysis in general, and excellent chance for the development of viable industrial processes for conversion of renewable biomass into bio-based chemicals. Gold nanocatalysts have been studied and exhibit excellent catalytic properties and high selectivity in various reactions, especially catalytic oxidations, however gold has a limited impact on industrial catalysis. A challenge still to be overcome is the preparation of catalysts of controlled size that are sufficiently stable, while maintaining an acceptable activity and selectivity to real conditions. We have been working on the development of catalytic systems based gold and gold combined with other metals (eg Pd, Cu, Pt) for oxidation of alcohols, poliols and sugars. The oxidation of alcohols or sugars by gold catalysts has been studied in our group with excellent results (see Selective oxidation).
The development of metal nanoparticle heterogeneous catalysts for those transformations are highly desired and much has still to be improved in terms of selectivity, stability, separation, handling, reuse, and costs for large-scale productions.
Wojcieszak, R.; Cuccovia, I. M. ; Silva, M. A.; Rossi, L. M. . Selective oxidation of glucose to glucuronic acid by cesium-promoted gold nanoparticle catalyst. Journal of Molecular Catalysis. A, Chemical, p. 35-42, 2016.
Ferraz, C. P ; Garcia, M. A. S.; Teixeira-Neto, E.; Rossi, L. M. Oxidation of benzyl alcohol catalyzed by gold nanoparticles under alkaline conditions: weak vs strong bases. RSC Advances, v. 6, p. 25279-25285, 2016.
Oliveira, R. L. ; Kiyohara, P. K. ; Rossi, L. M. High performance magnetic separation of gold nanoparticles for catalytic oxidation of alcohols. Green Chemistry, v. 12, p. 144-149, 2010.
Silva, T. A. G. ; Landers, R.; Rossi, L. M. Magnetically recoverable AuPd nanoparticles prepared by a coordination capture method as a reusable catalyst for green oxidation of benzyl alcohol. Catalysis Science & Technology, p. 2993-2999, 2013.
Silva, T. A. G. ; Teixeira-Neto, E.; López, N.; Rossi, L.M. Volcano-like Behavior of Au-Pd Core-shell Nanoparticles in the Selective Oxidation of Alcohols. Scientific Reports, v. 4, p. 5766, 2014.
CO2 HYDROGENATION (RWGS)
Gonçalves, R. V. ; Vono, L. L.R. ; Wojcieszak, R.; Dias, C. S.B. ; Wender, H.; Teixeira-Neto, E.; Rossi, L. M. Selective hydrogenation of CO2 into CO on a highly dispersed nickel catalyst obtained by magnetron sputtering deposition: A step towards liquid fuels. Applied Catalysis. B, Environmental, v. 209, p. 240-246, 2017.