Hierarchically porous polymers: novel heterogeneous platinum catalysts for sustainable silicon industry applications

Platinum (Pt) catalyzed hydrosilylation of alkenes has known as the most efficient reaction method for the synthesis of industrial functional silicones and has emerged as one of the largest applications of industrial homogeneous catalysis over the last 50 years [1]. In the context of the evolving silicon industry, the need for sustainable and efficient catalytic processes that can replace commercial homogeneous Pt catalyst such as Speier and Karstedt is paramount. In order to reduce the catalyst cost of the Pt-catalyzed alkene hydrosilylation, studies to develop a heterogeneous catalyst design in which the Pt metal can be reused with minimal activity loss are therefore is very crucial. Among the heterogeneous catalyst support materials, styrenic polyHIPEs stand out with their relatively low cost and facile synthesis method. Their dual-sized macro-dimensional porosity can be upgraded to homogeneously dispersed meso-micro porosity by hypercrosslinking method. Free alkyl halide functional groups originating from vinyl benzyl chloride monomer present on the surface of hypercrosslinked polyHIPE (HCLPH) can be utilized for chemical binding of the metal-ligand complex to provide catalytic activity. This research presents novel heterogeneous Pt catalysts which are hierarchical porous HCLPH support containing Markó-type NHC-Pt complex structures designed specifically for industrial alkene hydrosilylation applications. In depth chemical and morphological characterization of novel Pt catalyst have been performed by using X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy and Energy Dispersive Spectroscopy (SEM-EDS), Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Thermogravimetric Analysis (TGA), and BET surface area and porosity analysis techniques. Comparative studies with industry standard Speier and Karstedt catalysts for the alkene hydrosilylation monitored with GC-MS and 1H-NMR reveals that these novel catalysts not only match the catalytic performance of commercial catalysts with the same amount of Pt, but also provides at least ten catalytic cycles without any loss of activity. The unique hierarchical architecture of the support facilitates superior mass transfer and active site accessibility, resulting in enhanced catalytic performance. This research underlines the potential of these novel heterogeneous Pt catalysts to contribute to sustainable silicon production by maximizing resource utilization in industry while maintaining high efficiency alkene hydrosilylation.

Reference(s):

[1] Hofmann, R., Vlatkovi?, M., Wiesbrock, F. 2017. “Fifty years of hydrosilylation in polymer science: A review of current trends of low-cost transition-metal and metal-free catalysts, non-thermally triggered hydrosilylation reactions, and industrial applications”, Polymers, 9(12), 534.

Merve Süslükaya holds a Bachelor's degree in Chemical Engineering and a Master's degree in Polymer Science & Technology from Istanbul Technical University. Currently, she is pursuing a PhD in Chemistry at Bursa Technical University, while at the same time working on the development of industrial functional silicones at Sözal Kimya company. Her expertise includes development of high performance polymeric porous materials for industrially-important chemical transformations and separation/purification applications, as well as development of functional silicone copolymers.