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Molybdenum and nickel-molybdenum nitride catalysts supported on MgO-Al2O3 for the dry reforming of methane
Journal of CO2 Utilization ( IF 7.2 ) Pub Date : 2020-12-28 , DOI: 10.1016/j.jcou.2020.101411
Nicolas Abdel Karim Aramouni , Joseph Zeaiter , Witold Kwapinski , James J. Leahy , Mohammad N. Ahmad

Molybdenum and nickel-molybdenum nitride catalysts supported on MgO-Al2O3 were synthesized and tested for methane dry reforming at temperatures of 760−840 °C. Two in-situ nitridation procedures involving heating the catalyst in NH3/N2 or H2/N2 gas at a space velocity of 44 s−1 and 5 °C/min heating rate, were assessed and compared with a conventional reduction procedure. The activity of the bimetallic nitride was much higher than that of molybdenum nitride, with a slightly better performance with H2/N2-treated catalysts. The nitrides showed deactivation and poor stability at atmospheric pressure. The nitride phase was shown to transition into an oxide/carbide phase during reaction. Furthermore, hydrogen/nitrogen treatment caused partial reduction to occur, which explains the activity improvement in bimetallic Ni-Mo nitrides. Whisker carbon was significantly decreased although carbon formation was observed. The basic support improves coking resistance by enhancing CO2 adsorption. Initial results indicate a unique activation site for both methane and CO2 through a Mars-Van Krevelen mechanism, with a phase transformation followed by a carbide-oxide redox cycle mechanism taking place.



中文翻译:

MgO-Al 2 O 3上担载的甲烷干重整用钼和镍钼氮化物催化剂

合成了负载在MgO-Al 2 O 3上的钼和镍钼氮化物催化剂,并在760-840°C的温度下进行了甲烷干重整测试。评估了两种原位氮化程序,涉及在NH 3 / N 2或H 2 / N 2气体中以44 s -1的空速和5°C / min的加热速率加热催化剂,并将其与常规还原程序进行比较。双金属氮化物的活性远高于氮化钼,在H 2 / N 2下的性能稍好。处理的催化剂。氮化物在大气压下表现出失活和稳定性差。氮化物相在反应过程中转变为氧化物/碳化物相。此外,氢/氮处理引起部分还原的发生,这解释了双金属Ni-Mo氮化物的活性提高。尽管观察到碳形成,但晶须碳显着降低。碱性载体通过增强CO 2吸附来改善耐焦化性。初步结果表明,通过Mars-Van Krevelen机理,甲烷和CO 2均具有独特的活化位点,随后发生相变,随后发生碳化物-氧化还原循环机理。

更新日期:2020-12-28
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