As a new kind of Halon replacement, 2-bromo-3,3,3-trifluoropropene (2-BTP) is finding application as a fire extinguishing agent in confined spaces. For assessing its environmental impact, it is necessary to perform kinetic and product studies of its degradation in the atmospheric environment. In this sense, five possible reaction pathways between 2-BTP and OH radicals are found by Gaussian 03. Detailed analysis shows that the main product is the CF3CBrCH2OH radical, which may produce a series of compounds by further reaction with O2, NO, etc. In order to further prove the validity of the theoretical calculations and investigate the atmospheric transformation process of 2-BTP, atmospheric degradation of 2-BTP is then studied experimentally under controlled radiation conditions. Based on the theoretical analyses and experimental results, the atmospheric degradation mechanism of 2-BTP is finally proposed and detailed information on the atmospheric chemistry of 2-BTP is provided.
High-surface-area chromium-based catalysts in the presence of a small amount of zinc were prepared via a sol-gel auto-combustion method using chromic nitrate, zinc nitrate, and citric acid. First, the auto-combustion behavior of the dried gel was investigated by derivative thermogravimetry and (DTG)-TG and infrared (IR) techniques. The results revealed that the dried gel exhibited self-propagating combustion properties. Second, the as-burnt powders were characterized by IR, X-ray diffraction (XRD), Brunauer-Emmett-Teller analysis (BET), and scanning electron microscopy (SEM). The findings showed that the gels were directly converted into CrZn-O nanoparticles with high surface area during the auto-combustion process. Third, the pre-fluorination Cr-Zn catalysts were characterized by XRD, BET, SEM, X-ray photoelectron spectroscopy (XPS), and Fourier transform (FT)-IR spectroscopy of pyridine adsorption techniques. It was found that the presence of zinc led to significant structural changes in the catalyst, the particle size was smaller, the surface area became larger, and more active sites appeared. Finally, the catalytic activities of the samples were tested for the fluorination of 1,2-dichlorohexafluorocyclopentene (1,2-F6) with anhydrous hydrogen fluoride. The obtained results indicated that the pre-fluorination activated Cr-Zn catalysts prepared by this sol-gel auto-combustion method exhibited high efficiency in the synthesis of cyclic hydrofluorocarbons.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.