Resources Recycling ISSN:2765-3439(Print) 2765-3447(Online) 자원리싸이클링

Transition-metal carbonitrides (TMCNs) are composed of transition metals (Ti, V, Cr, Mo, W, etc.) in combination with carbon and nitrogen. TMCNs possess a unique combination of ceramic-like properties such as high thermal stability and wear resistance, as well as metallic properties such as high electrical conductivity. TMCNs are synthesized via the carbothermal reduction of transition-metal oxides with carbon under a nitrogen atmosphere. In this process, highly purified carbon sources are required to minimize the oxygen and impurity contents of the resulting carbonitrides. In this study, carbon feedstock pretreatment and carbonitride synthesis were optimized to produce high-purity TMCNs using carbon byproducts generated during turquoise hydrogen production as alternative carbon sources. Metallic impurities in the carbon byproducts were removed by acid washing, while the oxygen content was reduced by thermal treatment prior to carbonitride synthesis. The physicochemical properties of the pretreated carbon feedstocks were systematically compared with those of conventional commercial carbon sources such as graphite, carbon black, activated carbon, and coke to evaluate the feasibility of their use in TMCN synthesis. Furthermore, variations in the carbon-to-nitrogen (C/N) ratio of the synthesized carbonitrides were investigated by thermal analysis and thermodynamic calculations, and a process design strategy for controlling the C/N ratio in TMCNs was proposed. The results demonstrated the potential of carbon byproducts from turquoise hydrogen production and biomass-derived carbon as sustainable alternative feedstocks for the synthesis of high-purity TMCNs. This study also provides a systematic approach for controlling the C/N ratio of TMCNs by optimizing the feedstock pretreatment and synthesis conditions.