자원리싸이클링 (Resources Recycling)

  • 제31권1호
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  • Pages.29-36
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  • 2022
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  • 2765-3439(pISSN)
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  • 2765-3447(eISSN)
한국자원리싸이클링학회 (The Korean Institute of Resources Recycling)
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MoO3 분말의 수소환원거동

The Hydrogen Reduction Behavior of MoO3 Powder

  • 구원범 (한국해양대학교 에너지자원공학과) ;
  • 유경근 (한국해양대학교 에너지자원공학과) ;
  • 김행구 (한국해양대학교 에너지자원공학과)
  • 투고 : 2021.11.26
  • 심사 : 2021.12.22
  • 발행 : 2022.02.28
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초록

수평관상로를 사용하여 산화몰리브덴의 수소환원거동을 연구하였으며, 환원은 MoO3 → MoO2과 MoO2 → Mo의 두 단계로 진행되었다. 첫 번째 단계에서는 높은 발열반응을 고려하여 MoO3 환원을 위해 30 vol% H2와 70 vol% Ar의 혼합 가스를 선택하였다. 온도 범위는 550~600℃이고 체류 시간 범위는 30~150분으로 진행하였다. 두 번째 단계에서는 MoO2의 환원을 위해 순수한 H2 가스를 사용하였으며, 온도와 체류시간의 범위는 각각 700~750℃와 30~150분이었다. 몰리브덴 산화물의 두 단계의 수소환원과정에서 각각 다른 환원거동이 관찰되었다. 1단계에서는 반응속도의 온도 의존성이 관찰되었으며, 본 연구의 조건에서 중간 산화물의 존재에도 불구하고 표면반응율 속 메커니즘이 결과와 잘 일치하는 것으로 나타났다. 이 메커니즘을 기반으로 활성화 에너지와 빈도인자는 각각 85.0 kJ/mol 및 9.18×107로 계산되었다. 또한, 입자 내 기공 크기는 온도 및 체류 시간에 따라 증가했다. 2단계 환원의 경우 반응속도의 온도 의존성이 관찰되었으나 표면반응율속 메커니즘은 초기에만 부합하였다. 이는 환원과정 후반부에 상변태 MoO2→ Mo가 진행됨에 따라 부피 변화에 의한 산화물 결정구조의 붕괴에 기인한다고 생각할 수 있다.

The hydrogen reduction behavior of molybdenum oxides was studied using a horizontal-tube reactor. Reduction was carried out in two stages: MoO3 → MoO2 and MoO2 → Mo. In the first stage, a mixed gas composed of 30 vol% H2 and 70 vol% Ar was selected for the MoO3 reduction because of its highly exothermic reaction. The temperature ranged from 550 to 600 ℃, and the residence time ranged from 30 to 150 min. In the second step, pure H2 gas was used for the MoO2 reduction, and the temperature and residence time ranges were 700-750 ℃ and 30-150 min, respectively. The hydrogen reduction behavior of molybdenum oxides was found to be somewhat different between the two stages. For the first stage, a temperature dependence of the reaction rate was observed, and the best curve fittings were obtained with a surface reaction control mechanism, despite the presence of intermediate oxides under the conditions of this study. Based on this mechanism, the activation energy and pre-exponential were calculated as 85.0 kJ/mol and 9.18 × 107, respectively. In addition, the pore size within a particle increases with the temperature and residence time. In the second stage, a temperature dependence of the reaction rate was also observed; however, the surface reaction control mechanism fit only the early part, which can be ascribed to the degradation of the oxide crystals by a volume change as the MoO2 → Mo phase transformation proceeded in the later part.

키워드

과제정보

This work was supported by Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government (MOTIE) (20217510100020, Development of platform process using common core and materialization technology for rare metal recovery from industrial low-grade waste liquid).

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