New Bimetal Catalysts Supported on Silica Nanospheres for the Production of Synthetic Diesel

Abstract

Nowadays we are facing the necessity to find new ways to reduce the use of fossil fuels. This need comes from the excessive use of these sources as energy and the well-known adverse environmental effects than these fuels represents. Currently the fossil fuels represents about the 70% of the world energy sources. This dependency has brought some important problems of contamination such as global warming and climate change, acid rain, alterations of the carbon cycle, among many others. The transportation sector is the largest consumer of petroleum-based fuels in the world, liberating to the atmosphere vast amounts of CO2, NOx, SOx, lead (Pb), mercury (Hg), and many others. These pollutants are not only harmful to the environment but also to the human health, causing lung and heart diseases along with cancer. The increase of price and demand of these fuels and the contamination generated by them makes imperative the search of viable clean technologies looking for the production of clean fuels with high commercial value. Contaminants produced by the combustion of fossil fuels represent a challenging future for the development of new clean fuels. In this regard, an interesting alternative consists in the synthesis of clean diesel fuel thorough the Fischer-Tropsch (FT) reaction. This method produces clean diesel starting from a mixture of H2 and CO obtained from renewable or not renewable energy sources. This synthesis produces high weighted hydrocarbons with high purity. The fuel produced by this process is clean since it does not have aromatic compounds or sulphur or nitrogen-based compounds, preventing the production and release of NOx and SOx during combustion. The FT processes require the use of heterogeneous catalysts. These catalysts are based on active metals (i.e. Co, Ru or Fe) highly dispersed on the surface of appropriate supports. In this research SiO2 nanospheres, synthesized by using the Stӧber procedure, have been used as supports for the deposition of different metals on the surface. The synthesized catalysts were characterized by FE-SEM, HRTEM, XRD and BET, and used for the FT reaction. Preliminary catalytic results are very promising and show that mixtures of low loadings of bimetal nanoparticles dispersed on the surface of SiO2 nanospheres could be efficiently used for the synthesis of paraffin products with different distribution.