Improving the synthesis of heterogeneous catalysts by gliding arc plasma using the “no-cooling system”

Glidarc plasma (GP) is a promising method for preparing heterogeneous catalysts due to its mild conditions and short processing time. This technique has been used to synthesize various catalysts like FeOx and MnOx. Adding a post-discharge (PD) step during synthesis has been shown to impart valuable new properties, such as phase transformation, increased specific surface area, and enhanced catalytic activity. Knowing that the PD step mostly impacts the plasma-synthesized solids maturation and can be accelerated if heat is introduced into the system, we now contemplate the possibility of accelerating the GP catalysts synthesis by allowing the solution to be heated by the energy spontaneously provided by the plasma without the necessity to add a PD. To challenge this approach, we subjected FeSO and SnSO precursors to plasma exposure without employing the cooling system usually integrated in the GP set-up and compared the resulting solids with those obtained via conventional GP synthesis involving a PD step. The findings show that for iron precursors, the absence of cooling accelerates the formation of non-catalytically active phases and causes particle agglomeration, which is undesirable. However, for tin precursors, the absence of a cooling system introduces features that further improve the catalytic activity of the solids. Precisely, tin oxide phases developed better than other less-catalytically active ones without affecting the textural properties of the solid. This suggests that in some cases, eliminating the PD step can simplify the GP catalyst synthesis process and reduce its environmental and economic impact.