Single step production of styrene from benzene by alkenylation over palladium-anchored thermal defect rich graphitic carbon nitride catalyst

Styrene is a widely used monomer in polymer industries for the manufacturing of plastics, rubbers and resins. The commercial styrene production process suffers from disadvantages such as requiring multiple steps, catalyst deactivation, high energy consumption and low yield. To address the aforementioned problems, metal complex catalysed single-step oxidative coupling of benzene and ethylene to styrene have been proposed. The attempts so far for the heterogenization of metal complexes lead to worsening the catalytic performance due to metal leaching or clustering. Here, we have presented a first step towards the development of a heterogeneous catalyst to synthesize styrene directly from benzene and ethylene in a single- step. We have anchored palladium nanoparticles on the thermal defect rich surface of graphitic carbon nitride and prepared a heterogeneous catalyst (Pd@d-C3N4) that is active for the single-step styrene production. The product and side-products were analysed by gas chromatography coupled with mass spectrometry. To understand the role of active sites, the catalysts were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), Brunauer-Emmett-Teller (BET) and Fourier-transform infrared (FT-IR) spectroscopy techniques. A combination of microscopic and spectroscopic characterization supports the hypothesis that the activity of Pd@d-C3N4 catalyst is associated with their layered structure, surface defect site, and well-stabilized palladium nanoparticles.