Saconsint Supanida, Srifa Atthapon, Koo-Amornpattana Wanida, Assabumrungrat Suttichai, Sano Noriaki, Fukuhara Choji, Ratchahat Sakhon
Department of Chemical Engineering, Faculty of Engineering, Mahidol University, Nakhon Pathom, 73170, Thailand.
Department of Chemical Engineering, Faculty of Engineering, Center of Excellence in Catalysis and Catalytic Reaction Engineering, Chulalongkorn University, Bangkok, 10330, Thailand.
Sci Rep. 2023 Aug 9;13(1):12928. doi: 10.1038/s41598-023-38436-8.
Biogas has been widely regarded as a promising source of renewable energy. Recently, the direct conversion of biogas over heterogeneous catalysts for the simultaneous production of syngas and carbon nanotubes exhibits a high potential for full utilization of biogas with great benefits. Involving the combined dry reforming of methane and catalytic decomposition of methane, the efficiency of process is strongly depended on the catalyst activity/stability, mainly caused by carbon deposition. In this study, Ni-Mo catalyst is engineered to provide a life-long performance and perform high activity in the combined process. The surface modification of catalysts by a controlled carburization pretreatment is proposed for the first time to produce a carbide catalyst along with improving the catalyst stability as well as the reactivity for direct conversion of biogas. The performance of as-prepared carbide catalysts is investigated with comparison to the oxide and metallic ones. As a result, the Ni-MoC catalyst exhibited superior activity and stability over its counterparts, even though the condensed nanocarbon was largely grown and covered on the surface. In addition, up to 82% of CH conversion and 93% of CO conversion could remain almost constant at 800 °C throughout the entire test period of 3 h under a high flowrate inlet stream of pure biogas at 48,000 cm g h. The XPS spectra of catalysts confirmed that the presence of MoC species on the catalyst surface could promote the stability and reactivity of the catalyst, resulting in higher productivity of carbon nanotubes over a longer time.
沼气已被广泛视为一种有前途的可再生能源。最近，在多相催化剂上直接将沼气转化以同时生产合成气和碳纳米管，在充分利用沼气方面具有很大潜力且益处多多。该过程涉及甲烷的联合干重整和甲烷的催化分解，其效率在很大程度上取决于催化剂的活性/稳定性，主要原因是积碳。在本研究中，设计了镍钼催化剂以实现长期性能并在联合过程中表现出高活性。首次提出通过可控渗碳预处理对催化剂进行表面改性，以制备碳化物催化剂，同时提高催化剂稳定性以及沼气直接转化的反应活性。将制备的碳化物催化剂的性能与氧化物和金属催化剂进行了比较研究。结果表明，尽管大量凝聚的纳米碳在表面生长并覆盖，但镍碳化钼催化剂的活性和稳定性优于同类催化剂。此外，在48,000 cm³ g⁻¹ h⁻¹的纯沼气高流速进口气流下，在800°C的整个3小时测试期间，高达82%的CH₄转化率和93%的CO转化率几乎可以保持恒定。催化剂的XPS光谱证实，催化剂表面MoC物种的存在可以提高催化剂的稳定性和反应活性，从而在更长时间内实现更高的碳纳米管生产率。
