Au/TS-1 catalyst for propylene epoxidation with H2 and O2: Effect of surface property and morphology of TS-1 zeolite

The catalytic performances over propylene epoxidation with H2 and O2 (HOPO process) are significantly affected by the properties (e.g., surface properties, Ti coordination, morphology) of titanosilicate zeolite. Introducing urea into zeolite synthesis is a simple convenient method to modify these Uncalcined pore-blocked titanium silicalite-1 (TS-1, i.e., TS-1-B) lower dosage possesses more defective structure unsaturated coordinated sites verified 29Si nuclear magnetic resonance (NMR) X-ray photoelectron spectroscopy (XPS) analysis, which results in high initial activity hydrogen efficiency; while acidity generated species leads continuous decrease oxide (PO) selectivity during reaction. As amount gradually increases, TS-1-B samples present reduced defects species. Specially, TS-1-B-0.30U presents weaker PO adsorption on PO-diffusion reflectance infrared Fourier transform spectra (DRIFTS), thus stable formation rate its Au catalyst. Furthermore, flat-plate-like shape shorter thickness 100 nm along b-axis direction observed urea-modified TS-1. Compared conventional ellipsoidal TS-1 crystal sizes 200 500 nm, TS-1-0.30U displays less defects, species, Lewis acid, favorable for desorption intracrystalline diffusion PO, reduces occurrence side reactions improved stability. This work may provide reference developing titanium-containing materials stability HOPO