The current work describes an attempt to synthesize hybrid materials combining porous aromatic frameworks (PAFs) and dendrimers and use them to obtain novel highly active and selective palladium catalysts. PAFs are carbon porous materials with rigid aromatic structure and high stability, and the dendrimers are macromolecules which can effectively stabilize metal nanoparticles and tune their activity in catalytic reactions. Two porous aromatic frameworks, PAF-20 and PAF-30, are modified step-by-step with diethanolamine and hydroxyl groups at the ends of which are replaced by new diethanolamine molecules. Then, palladium nanoparticles are applied to the synthesized materials. Properties of the obtained materials and catalysts are investigated using X-ray photoelectron spectroscopy, transmission electron microscopy, solid state nuclear magnetic resonance spectroscopy, low temperature N2 adsorption and elemental analysis. The resulting catalysts are successfully applied as an efficient and recyclable catalyst for selective hydrogenation of alkynes to alkenes at very high (up to 90,000) substrate/Pd ratios.
AbstractIn this study, two oil fractions – straight-run diesel and light cycle oil (LCO) – and the products of their hydrotreatment with sulfide catalysts, synthesized in the pores of porous aromatic frameworks, were analyzed by comprehensive two-dimensional gas chromatography (GC) with time of flight mass spectrometry (GC × GC–TOFMS). Effective separation of numerous compounds in the analyzed multicomponent mixtures and high resolution of mass spectra of reaction products made it possible to study the features of the activity of sulfide catalysts.
This study focuses on the hydrogenation of model lignin bio-oil components over ruthenium and platinum catalysts synthesized from a porous aromatic framework, namely PAF-30. This PAF represents a polymeric support with developed porosity and high chemical and thermal stability. The effects of the guaiacol concentration, process temperature, and reaction time on the product composition were identified in the catalytic hydrogenation of guaiacol as a common component of lignin bio-oil. Various guaiacol derivatives were hydrogenated, and the hydrogenate composition was investigated. It was demonstrated that, within one hour at 250°C and a hydrogen pressure of 3 MPa, guaiacol can be hydrogenated exhaustively into 2-methoxycyclohexanol (64%) and cyclohexanol (64%) over the ruthenium catalyst and into a mixture of various hydrogenation products over the platinum catalyst.
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