Propene epoxidation with H2 and O2 on Au/TS-1 catalyst: Cost-effective synthesis of small-sized mesoporous TS-1 and its unique performance

Photocatalytic Performance and Degradation Pathway of Rhodamine B with TS-1/C3N4 Composite under Visible Light

TS-1/C3N4 composites were prepared by calcining the precursors with cooling crystallization method and were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), UV-Vis diffuse reflection spectrum (DRS) and nitrogen adsorption-desorption isotherm. The photocatalytic performance of TS-1/C3N4 composites was investigated to degrade Rhodamine B (RhB) under visible light irradiation. The results showed that all composites exhibited better photocatalytic performance than pristine TS-1 and C3N4; TS-1/C3N4-B composite (the measured mass ratio of TS-1 to C3N4 is 1:4) had best performance, with a rate constant of 0.04166 min-1, which is about two and ten times higher than those of C3N4 and TS-1, respectively. We attributed the enhanced photocatalytic performance of TC-B to the optimized heterostructure formed by TS-1 and C3N4 with proper proportion. From the results of photoluminescence spectra (PL) and the enhanced photocurrent, it is concluded that photogenerated electrons and holes were separated more effectively in TS-1/C3N4 composites. The contribution of the three main active species for photocatalytic degradation followed a decreasing order of ·O2-, ·OH and h+. The degradation products of RhB were identified by liquid chromatography tandem mass spectrometry (LC-MS/MS), and the possible photocatalytic degradation pathways were proposed.

Titanium silicalite as a radical-redox mediator for high-energy-density lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are receiving intense interest owing to their high energy densities, cost effectiveness, and the natural abundance of sulfur. However, practical applications are still limited by rapid capacity decay caused by multielectron redox reactions and complex phase transformations. Here, we include commercially available titanium silicalite-1 (TS-1) in carbon/sulfur cathodes, to introduce strong chemical interactions between the lithium polysulfides (LiPS) and TS-1 in a working Li-S battery. In situ UV-visible spectroscopy together with other experimental results confirm that incorporation of TS-1 mediators enables direct conversion between S₈^2- and S₃*^- radicals during the discharge process, which effectively promotes the kinetic behaviors of soluble LiPS and regulates uniform nucleation and growth of solid sulfide precipitates. These features give our TS-1 engineered sulfur cathode an ultrahigh initial capacity of 1459 mA h g^-1 at 0.1C. Moreover, the system has an impressively high areal capacity (3.84 mA h cm^-2) and long cycling stability with a high sulfur loading of 4.9 mg cm^-2. This novel and low-cost fabrication procedure is readily scalable and provides a promising avenue for potential industrial applications.

Adsorptive Removal of Acetaldehyde from Propylene Oxide Produced by the Hydrogen Peroxide to Propylene Oxide Process

Adsorption method was first introduced into the propene oxide production via hydrogen peroxide process to remove the microimpurity in the propylene oxide (PO) product solution. It could replace the reactive distillation in separating acetaldehyde with less energy consumption and PO loss. A series of adsorbents (e.g., 3A, 4A, 5A, 10X, and Y) are first used to remove the impurity (i.e., acetaldehyde). It is found that 5A molecular sieves shows the best performance due to uniform porous channels with suitable pore size. Various techniques such as X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared, and N₂ physisorption are employed to investigate the structural properties of the adsorbent. Furthermore, effects of space velocity and temperature are also investigated. Cyclic desorption and adsorption tests indicate the PO yield is 92.2%, and 96.3% of acetaldehyde was removed. The acetaldehyde concentration of PO product was 0.0187%, indicating this method can produce industrial-quality PO that meets the first-level technical requirements.