Cooperative Effect of Ni-Decorated Monolayer WS2, NiO, and AC on Improving the Flame Retardancy and Mechanical Property of Polypropylene Blends

Improving the residual char of polypropylene (PP) is difficult due to the preferential complete combustion. Here, we designed a combination catalyst that not only provides physical barrier effects, but also dramatically promotes catalytic charring activity. We successfully synthesized WS₂ monolayer sheets decorated with isolated Ni atoms that bond covalently to sulfur vacancies on the basal planes via thiourea. Subsequently, PP blends composed of 8 wt.% Ni-decorated WS₂, NiO, and activated carbon (AC) were obtained (^ENi-^SWS₂-AC-PP). Combining the physical barrier effects of WS₂ monolayer sheets with the excellent catalytic carbonization ability of the ^ENi-^SWS₂-AC combination catalyst, the PP blends showed a remarkable improvement in flame retardancy, with the yield of residual char reaching as high as 41.6 wt.%. According to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations, it was revealed that the microstructure of residual char contained a large number of carbon nanotubes. The production of a large amount of residual char not only reduced the release of pyrolytic products, but also formed a thermal shield preventing oxygen and heat transport. Compared to pure PP, the peak heat release rate (pHRR) and total heat release rate (THR) of ^ENi-^SWS₂-AC-PP were reduced by 46.32% and 26.03%, respectively. Furthermore, benefiting from the highly dispersed WS₂, the tensile strength and Young's modulus of ^ENi-^SWS₂-AC-PP showed similar values to pure PP, without sacrificing the toughness.

Synthesis of NiW catalysts supported on hierarchically meso/microporous KIT-5/Beta composites and their hydrodenitrogenation performance of quinoline

Meso/microporous composite material KIT-5/Beta (KB) with a cubic Fm3m mesoporous structure and BEA microporous structure was successfully synthesized by an in situ assembly method.

Synthesis of NiW Supported on an Al-Modified Cubic Ia3d Mesoporous KIT-5 Catalyst and Its Hydrodenitrogenation Performance of Quinoline

Pure KIT-5 and a series of Al-KT-X materials modified by different amounts of aluminum were synthesized by a direct hydrothermal method and acted as supports for the catalysts of a quinoline hydrodenitrification reaction with the NiW active phases supported. The results of X-ray diffraction (XRD), N2 isotherm absorption-desorption, scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) for the supports indicated that Al species were embedded into the framework of the KIT-5 materials with a large pore size, pore volume, and specific surface area. The Pyridine-Fourier transform infrared spectroscopy (Py-IR) result of the catalysts demonstrated that the addition of aluminum atoms enhanced the acidity of the catalysts. The results of the high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectra (XPS) characterizations for the sulfide catalysts indicated that the embedded Al species could facilitate the dispersion of active metals and the formation of the active phases. Among all the catalysts, NiW/Al-KT-40 showed the maximal hydrodenitrogenation conversion (HDNC) due to its open three-dimensional pore structure, appropriate acidity, and good dispersion of active metals.

Ring opening of decalin over bifunctional Ni–W carbide/Al2O3–USY catalysts and monofunctional acid Ni–W oxide/Al2O3–USY

The ring opening reaction of decalin was studied over two types of catalyst, including bifunctional catalysts (Ni–W carbide/Al₂O₃–USY) and monofunctional acid catalysts (Ni–W oxide/Al₂O₃–USY) with different amounts of metal loading.