Summary Catalytic dehydrogenation of ethane (EDH) is promising for the utilization of shale gas to produce ethylene, but the current processes mostly exhibit space-time productivity of ethylene lower than 1.5 Kg C2H4 Kg cat −1 h −1 because of the insufficient catalyst activity in the non-oxidative route. We reported a catalyst with isolated cobalt in siliceous zeolite derived from a mechanically assisted spontaneous dispersion. This material can operate as a non-oxidative EDH catalyst at thermodynamically limited conversion levels under rapid gas feeding, resulting in ethylene productivity at 13.4 Kg C2H4 Kg cat −1 h −1 . This result is superior to that of the previous non-noble metal catalysts and even outperforms the precious PtSn/Al 2 O 3 catalyst. The isolated cobalt sites are preserved upon calcination at high temperatures and during EDH operation under harsh conditions, resulting in superior durability in a long reaction period with negligible coke formation.
Shuai Chen,Feng Wu,Haolin Wang,Shuang Gao,Jiafu Chen,Zhimin Chen,Jianwei Fu
Ferric oxide (Fe 2 O 3 ) has become one of the most competitive candidates for the next-generation lithium-ion batteries anode materials due to its high theoretical reversible specific capacity (Cs, 1007 mAh g −1 ) and low price. However, the rapid capacity fading and poor rate performance deriving from drastic volume expansion (∼200 %), low Coulombic efficiency (CE), and poor electrical conductivity limit its application in LIBs. Herein, a novel encapsulation structure of Fe 2 O 3 nanoparticles has been developed. Fe 2 O 3 nanoparticles inlaid in the shells of hollow highly graphitized carbon fibers are coated by N-doped graphitized carbon (GF-FeO@NGC) by a catalytic graphitization, oxidation route of Fe-based catalyst. The GF-FeO@NGC electrode shows the first specific discharge/charge capacities of 1355/974 mAh g −1 with high initial Coulombic efficiency (ICE) of 72.0%, and excellent reversibility of lithiation/delithiation reaction. After 200 cycles at 0.1 A g −1 , the GF-FeO@NGC electrode keeps a high reversible Cs of 918 mAh g −1 (retention of 94.3%) with a CE of 99.6%. It is noticeable that the GF-FeO@NGC electrode has good rate performance and robust cycling stability at high current density. After 300 cycles at 2 A g −1 , the Cs retention is up to 97.1% with a CE of 99.7%. These are far superior to those of the GF-FeO (without NGC coating) and the most reported Fe 2 O 3 -based electrode materials. The mechanism behind these phenomena are studied.
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