Study of the Hydrogenolysis of Chlorofluorocarbons over Nickel- Containing Mixed Metal Oxide Catalysts

• Main Authors: Lin, Jenq Hwang, 林正煌
• Other Authors: Liang, Jeng Jong
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/46529446714135971846

碩士 === 逢甲大學 === 土木及水利工程研究所 === 83 === This thesis is for the purpose of studying the hydrogeno- lysis of the chlorofluorocarbons over some nickle-containing mixed oxide catalysts. Their structures and micrographs were characterized by XRD and SEM. The result indicates that substitution of La by Sr affects activity due to the La2NiO4-, NiO-, and SrO2-phases in the catalytic structure, while the amount of each phases increases with increasing x. But, the activity does not increase with increasing amounts of these phases; the highest activity occur- ring at x=0.3 or 0.5. It is believed that the catalysts are poisoned by the chlo- rine and/ or fluorine, which are the products of the hydrogeno- lysis of CFC-12 or CFC-113. The behavior of the Cl- and/or F-poisoned catalysts can be well explained by the aids of ESCA and SEM/WDS spectra. It is found that the behavior of these catalysts depend on the amount of chemisorbed chlorine and/or fluorine. When the B site (Ni cation) is occupied by chlorine and/or fluorine the catalyst is deactivated and no further reaction occurs. However , when chlorine and/or fluorine atoms are adsorbed on the A sites (La or Sr cation), the activity will not be affected because the A cation are in general catalystic- ally inactive. For LaNiO3, La0.7Sr0.3NiO3, and La0.5Sr0.5NiO3 catalysts, the chlorine and fluorine are adsorbed on the B cation at low temperature, but desorbed at the temperature over 260℃ then the activity increasing quickly. The activity of La0.3Sr0.7NiO3 and SrNiO3 catalysts is lower as chlorine and fluorine atoms adsorbed on the B cation until reaction tempe- rature over 400℃. The mechanisms of the hydrogenolysis of CFC-12 and CFC-113 over these nickle-containing mixed oxide catalysts are proposed by the aids of GC/MS analysis for the products.