Ultrafast fabrication of Pd/C as a highly active and stable heterogeneous catalyst for hydrogenation synthesis of tris(hydroxymethyl)aminomethane under batch and flow

Tris(hydroxymethyl)aminomethane (Tris) and its derivatives serve as crucial biological buffers. Presently, Tris is predominantly synthesized by reducing tris(hydroxymethyl)nitromethane using conventional reducing agents such as hydrazine hydrate and metal powders. However, hydrazine hydrate poses a significant threat to aquatic life, while the use of reducing metal powders generates substantial solid waste, thereby exerting considerable environmental pressure in terms of green and sustainable chemistry. The utilization of non-homogeneous catalysts for hydrogenation reduction offers a viable solution to mitigate these issues. Yet, the exploration of non-homogeneous catalysts remains incomplete and lacks comprehensive research. In this study, a highly active Pd/C catalyst for the hydrogenation reduction of tris(hydroxymethyl)nitromethane was fabricated, through an ultrarapid high-temperature thermal shock (HTS) synthesis. The ultrafine Pd particles (∼5.5 nm) are uniformly distributed on the carbon substrate, rendering the catalyst high activity and stability. Additionally, we successfully combine this heterogeneous catalyst with continuous flow technology and achieve a continuous and stable production of Tris for >8 h, with a satisfying yield of ∼96 %. This report may shed light on the efficient fabrication of more ultrafine catalysts for hydrogenation reductions with high noble-metal utilization.