A two-step process was employed to convert methane or ethane to light olefins via the formation of an intermediate monoalkyl halide. A novel K4RuOCll0/TiO2 catalyst was tested for the oxidative chlorination of methane...A two-step process was employed to convert methane or ethane to light olefins via the formation of an intermediate monoalkyl halide. A novel K4RuOCll0/TiO2 catalyst was tested for the oxidative chlorination of methane and ethane. The catalyst had high selectivity for methyl and ethyl chlorides, 80% and 90%, respectively. During the oxychlorination of ethane at T〉~250~C, the formation of ethylene as a reaction product along with ethyl chloride was observed. In situ Fourier transform infrared studies showed that the key intermediate for monoalkyl chloride and ethylene formation is the alkoxy group. The reaction mechanism for the oxidative chlorina- tion of methane and ethane over the Ru-oxychloride catalyst was proposed. The novel fiber glass catalyst was also tested for the dehydrochlorination of alkyl chlorides to ethylene and propylene. Very high selectivities （up to 94%-98%） for ethylene and propylene formation as well as high stability were demonstrated.展开更多
Aluminized coating was prepared on K452 superalloy by chemical vapor deposition(CVD)technique.The oxidation/corrosion behavior of alloy and coating were investigated at 750℃in air,air with solid NaCl deposit and mois...Aluminized coating was prepared on K452 superalloy by chemical vapor deposition(CVD)technique.The oxidation/corrosion behavior of alloy and coating were investigated at 750℃in air,air with solid NaCl deposit and moist air with solid NaCl deposit,respectively.The microstructure and composition of samples were characterized by SEM/EDS and XRD techniques.The results demonstrated that aluminized coating exhibited better oxidation/corrosion resistance than K452 alloy in the three environments above.And the main oxidation and corrosion products of alloy were Cr_(2)O_(3)and NiO,respectively.This indicated that Ni participated in the corrosion process due to the depletion of Cr during accelerated corrosion.Therefore,the established corrosion scale was non-protective,which could not protect underlying alloy from accelerated corrosion.Contrarily,the main oxidation and corrosion products of coating were protective Al_(2)O_(3),which acted as a barrier to separate coating from NaCl and oxygen,interrupting the self-sustainable accelerated corrosion.Additionally,the presence of water vapor was beneficial in reducing the spallation of corrosion products within a short time.The mechanisms of K452 alloy and aluminized coating in the three environments above were discussed in detail.展开更多
文摘A two-step process was employed to convert methane or ethane to light olefins via the formation of an intermediate monoalkyl halide. A novel K4RuOCll0/TiO2 catalyst was tested for the oxidative chlorination of methane and ethane. The catalyst had high selectivity for methyl and ethyl chlorides, 80% and 90%, respectively. During the oxychlorination of ethane at T〉~250~C, the formation of ethylene as a reaction product along with ethyl chloride was observed. In situ Fourier transform infrared studies showed that the key intermediate for monoalkyl chloride and ethylene formation is the alkoxy group. The reaction mechanism for the oxidative chlorina- tion of methane and ethane over the Ru-oxychloride catalyst was proposed. The novel fiber glass catalyst was also tested for the dehydrochlorination of alkyl chlorides to ethylene and propylene. Very high selectivities （up to 94%-98%） for ethylene and propylene formation as well as high stability were demonstrated.
基金financially supported by the National Key R&D Program of China(No.2020YFB2010404)
文摘Aluminized coating was prepared on K452 superalloy by chemical vapor deposition(CVD)technique.The oxidation/corrosion behavior of alloy and coating were investigated at 750℃in air,air with solid NaCl deposit and moist air with solid NaCl deposit,respectively.The microstructure and composition of samples were characterized by SEM/EDS and XRD techniques.The results demonstrated that aluminized coating exhibited better oxidation/corrosion resistance than K452 alloy in the three environments above.And the main oxidation and corrosion products of alloy were Cr_(2)O_(3)and NiO,respectively.This indicated that Ni participated in the corrosion process due to the depletion of Cr during accelerated corrosion.Therefore,the established corrosion scale was non-protective,which could not protect underlying alloy from accelerated corrosion.Contrarily,the main oxidation and corrosion products of coating were protective Al_(2)O_(3),which acted as a barrier to separate coating from NaCl and oxygen,interrupting the self-sustainable accelerated corrosion.Additionally,the presence of water vapor was beneficial in reducing the spallation of corrosion products within a short time.The mechanisms of K452 alloy and aluminized coating in the three environments above were discussed in detail.
