A covalently conjugated MoS2/Fe3O4 magnetic nanocomposite as an efficient & reusable catalyst for H2 production

Thermal treatment of flame retardant plastics: A case study on a waste TV plastic shell sample

In this work, the combustion and pyrolysis characteristics of a waste TV plastic shell sample were investigated using a powerful Thermogravimetric-Fourier Infrared Spectrum-Mass Spectrum (TG-FTIR-MS) technique. The decomposition mechanisms of plastic waste and fate of bromines in both thermal processes were probed as well. The TG analysis revealed that the combustion rate was larger than that of pyrolysis at temperature of 456 °C below, whereas it decreased at temperature of 456-605 °C. As a result, the total weight loss was equivalent at temperature of 605 °C for both processes. The FTIR analysis indicated the plastic combusted vigorously at 300-500 °C and 800-900 °C. As a comparison, it decomposed drastically at 300-400 °C and 500-900° in pyrolysis. The MS analysis showed that the release of brominated products HBr, CH₃Br, C₂H₅Br, C₃H₅Br, C₃H₇Br and C₃H₅BrO increased with an increase of temperature and reached maximum at 400-600 °C in both thermal processes. The release intensities of larger molecules C₆H₅Br, C₆H₅BrO and C₆H₄Br₂ were in the descending order of C₆H₅Br > C₆H₄Br₂ > C₆H₅BrO. It was not significant in the evolved products and decomposition pathway for both thermal processes. The entire decomposition of TV plastic shell sample could be divided into three stages, taking account of the evolved products. The backbone in acrylonitrile butadiene styrene resin and tetrabromobisphenol A first broke at 350 °C below, resulting in the form of 2-bromophenol, styrene, acrylonitrile and polybutadiene. Subsequently, the resulted 2-bromophenol debrominated forming HBr, which further reacted with hydrocarbons resulting in various brominated derivates. In addition, many small molecules, including CO₂, CO and CH₄ were generated in this stage. Further increasing temperature to 550 °C above, larger brominated derivates decomposed and smaller molecules predominated.

High-Efficient and Recyclable Magnetic Separable Catalyst for Catalytic Hydrogenolysis of β-O-4 Linkage in Lignin

Lignin is recognized as a good sustainable material because of its great abundance and potential applications. At present, lignin hydrogenolysis is considered as a potential but challenging way to produce low-molecular-mass aromatic chemicals. The most common linkage between the structural units of lignin polymer is the β-O-4 aryl ether, which are primary or even only target chemical bonds for many degradation processes. Herein, a Pd-Fe₃O₄ composite was synthesized for catalytic hydrogenolysis of β-O-4 bond in lignin. The synthesized catalyst was characterized by XRD, XPS, and SEM and the lignin depolymerization products were analyzed by GC-MS. The catalyst showed good catalytic performance during the hydrogenolysis process, lignin dimer was degraded into monomers completely and a high yield of monomers was obtained by the hydrogenolysis of bagasse lignin. More importantly, the magnetic catalyst was separated conveniently by magnet after reaction and remained highly catalytically efficient after being reused for five times. This work has demonstrated an efficient & recyclable catalyst for the cleavage of the β-O-4 bond in lignin providing an alternative way to make better use of lignins.