RESUMO
Tandem catalysis is an attractive strategy to intensify chemical technologies. However, simultaneous control over the individual and concerted catalyst performances poses a challenge. We demonstrate that enhanced pore transport within a Co/Al2 O3 Fischer-Tropsch (FT) catalyst with hierarchical porosity enables its tandem integration with a Pt/ZSM-5 zeolitic hydrotreating catalyst in a spatially distant fashion that allows for catalyst-specific temperature adjustment. Nevertheless, this system resembles the case of close active-site proximity by mitigating secondary reactions of primary FT α-olefin products. This approach enables the combination of inâ situ dewaxing with a minimum production of gaseous hydrocarbons (18â wt %) and an up to twofold higher (50â wt %) selectivity to middle distillates compared to tandem pairs based on benchmark mesoporous FT catalysts. An overall 80 % selectivity to liquid hydrocarbons from syngas is attained in one step, attesting to the potential of this strategy for increasing the carbon efficiency in intensified gas-to-liquid technologies.
RESUMO
Acetylene to butadiene direct synthesis, via enyne cross-metathesis, is demonstrated with commercial ruthenium carbene catalysts. Using excess of ethylene, yields greater than 50% are obtained. High activity is observed in the first minute of the reaction (TOF > 800 h(-1) based on butadiene). Catalyst reusability and poisoning are discussed.
RESUMO
A sweet catalyst: A catalyst formed of Ru/functionalized silica-coated magnetite nanoparticles is highly efficient in the one-pot production of sorbitol and glycerol, starting from cellulose and in the absence of an external hydrogen source. The ease of recoverability of the catalyst from the solid residues, and its reuse without loss of activity or selectivity for several runs, is an important green element of the process.
