Proving and utilizing the catalytic functions of hydrogen spillover

The existence and catalytic functions of hydrogen spillover were proved for the first time by using Pt catalysts encapsulated in aluminosilicates allowing selective H₂ diffusion.

Article  |  Fall 2014

Hydrogen spillover has been studied for the last 50 years, but its nature, its catalytic functions, and even its existence remain topics of vigorous debate. This is a consequence of the lack of model catalysts that can provide direct evidence of the existence of hydrogen spillover and simplify the catalytic interpretation.

To clearly elucidate this controversial phenomenon in heterogeneous catalysis, Prof. Minkee Choi`s lab designed well-defined model catalysts that enable proof of the catalytic functions of hydrogen spillover. Platinum encapsulated in a dense aluminosilicate matrix with controlled diffusional properties and surface hydroxyl concentrations were designed to elucidate the catalytic functions of hydrogen spillover. The catalytic investigation and theoretical modelling show that surface hydroxyls, presumably Brønsted acids, are crucial for utilizing the catalytic functions of hydrogen spillover on the aluminosilicate surface (Figure 1). The catalysts with optimized nanostructure show remarkable activities in hydro-/dehydrogenation, but virtually no activity for hydrogenolysis (Figure 2). This distinct chemoselectivity may be beneficial in industrially-important hydroconversions, such as propane dehydrogenation to propylene, because the undesired hydrogenolysis pathway producing light hydrocarbons of low value (methane and ethane) is greatly suppressed.

The research group believes that the present understanding of the hydrogen spillover phenomenon can be used to design advanced heterogeneous catalysts with distinct chemoselectivities, enhanced catalytic lifetime, and remarkably increased catalytic activity.

Reference:

Juhwan Im, Hyeyoung Shin, Haeyoun Jang, Hyungjun Kim, and Minkee Choi* “Maximizing the catalytic function of hydrogen spillover in platinum-encapsulated aluminosilicates with controlled nanostructures” Nature Communications, 2014, 5, 3370

Additional links for more information:

http://www.nature.com/ncomms/2014/140225/ncomms4370/full/ncomms4370.html

http://egcl.kaist.ac.kr