Supported liquid metals: high‐technology catalysts in chemical synthesis

The development of high‐technology catalysts which combine selectivity, productivity, robustness and ease of processing at the highest possible level is the ultimate goal in the catalytic chemistry. One such system involves supported liquid metal catalysts which benefits from the simultaneous metallic and liquid natures of the liquid metals[1,2]. Unlike traditional heterogeneous catalysts, the catalytic process of the highly dynamic supported liquid metal catalysts does not proceed at the surface of the metal nanoparticles, but presumably at homogeneously distributed metal atoms at the surface of a liquid metallic phase. Indeed, supporting a dissolved catalytic active metal in a metallic solution merges some features of heterogeneous catalysis, particularly, easy product separation, with features of homogeneous catalysis, particularly, electronic–steric control, because of the formation of isolated metal sites in a certain metal matrix, which in turn presents different electronic features caused by the inter metallic interactions[3]. The existence of a liquid metal catalytically active phase in a catalyst seems to offer a number of very important features[4]: (a) A higher activity/selectivity because of the special nature of the atomically isolated active sites created in a liquid metal environment; (b) Resistance to active metal agglomeration; (c) Self-healing properties and insensitivity to coking because of the high dynamics of the liquid interface. In fact, by dissolving the active metal in a liquid metallic environment, uniform catalytic sites can be created that provide electronic and steric properties different from those of the supported solid metal nanoparticles. Here we review some supported liquid metal catalysts as the high‐technology catalysts for some of the catalytic important reactions such as formic acid dehydrogenation[5], alkane dehydrogenation[4], methane conversion to hydrogen and separable carbon[6] and so on. Also we survey the processing technologies for the preparation of our investigated supported liquid metal catalysts. We believe that this opens a wide field of new catalytic materials, which could provide a highly interesting research field for theoretical, fundamental and applied studies.