A new “ship-in-a-bottle” approach to making nano-sized intermetallic compound catalysts (materials that increase how fast chemicals can be made) offers more control over stability, activity, product selectivity, and conversion efficiency than possible before. The approach involves encapsulating the catalyst inside a “glass-bottle” made from porous silica (a.k.a. sand), and the ordered compound self-assembles, forming a designer ship in a bottle. The development of the new synthesis approach arose by integrating experimental and computational studies to show self-assembly and catalytic efficacy of metallic “line compound” catalysts. Theory has shown that line compounds have more favorable features than other nanocatalysts formed in so-called core-shell structures; for example, with the encapsulation used here they are more stable with temperature under reactions than core-shell nanoparticles. In addition, near 100% selectivity and conversion for specific reactions of feedstock to fuels and chemicals were demonstrated. This is one potentially high-impact method to deliver new highly efficient and low cost alternative catalyst for energy conversion. New catalysts that are more stable, contain less precious metals (cheaper), less poisoning (longer lifetimes), and operate at lower temperatures (cheaper and environmentally friendly) provide all these advantages.
“Ship-in-a-Bottle” synthesis for Pt nanoparticles encapsulated in SiO2 (PtX@mSiO2, X= Sn,Pb,Zn).
X is introduced by flowing metallic salt into a “bottle”. mSiO2 is permeable to reactants including furfural and hydrogen.
For conversion of furfural to alcohol, PtSn yields 100% conversion (2.7x over Pt) and gives 98% selectivity (4.3x over Pt).
A Ship-in-a-Bottle Strategy To Synthesize Encapsulated Intermetallic Nanoparticle Catalysts: Exemplified for Furfural Hydrogenation