In this study, we investigate the effect of thermal treatment/calcination on the stability and activity of a Na–Mn–W/SiO₂ catalyst for the oxidative coupling of methane. The catalyst performance and characterisation measurements suggest that the W species are directly involved in the catalyst active site responsible for CH₄ conversion. Under operating conditions, the active components, present in the form of a Na–W–O–Mn molten state, are highly mobile and volatile. By varying the parameters of the calcination protocol, it was shown that these molten components can be partially stabilised, resulting in a catalyst with lower activity (due to loss of surface area) but higher stability even for long duration OCM reaction experiments.

中文翻译：

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热处理对甲烷氧化偶合的Na–Mn–W / SiO2催化剂稳定性的影响

在这项研究中，我们研究了热处理/煅烧对Na–Mn–W / SiO ₂催化剂对甲烷氧化偶联的稳定性和活性的影响。催化剂性能和表征测量表明，W物种直接参与负责CH ₄转化的催化剂活性位。在运行条件下，以Na–W–O–Mn熔融态存在的活性成分具有很高的流动性和挥发性。通过改变煅烧方案的参数，表明这些熔融组分可以部分稳定，从而导致催化剂具有较低的活性（由于表面积的损失），但即使是长时间的OCM反应实验也具有较高的稳定性。