Enhanced Activity of WO x -Promoted PdNi Nanoclusters Confined by Amino-Modified KIT-6 for Dehydrogenation of Additive-Free Formic Acid

Formic acid (FA, HCOOH), featured as a major liquid product of biomass processing and especially a liquid sunshine carrier, thus becomes a renewable and promising liquid organic hydrogen carrier. It is highly desirable, but it remains a big challenge to develop a highly active heterogeneous catalyst with no or low content of noble metals for dehydrogenation of additive-free FA at ambient conditions. Herein, for the first time, WO x -modified PdNi alloy nanoclusters immobilized by amino-functionalized KIT-6 (PdNi-WO x /KIT-6-NH 2 ) are prepared through a simple and facile strategy at ambient conditions. PdNi-WO x clusters with an ultrasmall size of 1.4 nm are highly dispersed onto KIT-6-NH 2 support. The strong electronic coupling in PdNi-WO x NCs and electronic metal–support interaction between PdNi-WO x NCs and KIT-6-NH 2 support lead to the formation of electron-rich PdNi of PdNi-WO x /KIT-6-NH 2 . The resulting PdNi-WO x /KIT-6-NH 2 catalyst exhibits highly efficient catalytic activity and 100% hydrogen selectivity for formic acid dehydrogenation without extra additives, giving turnover frequency (TOF) values of 1699 h –1 at 303 K and 4417 h –1 at 323 K, which is higher than most of the heterogeneous catalysts ever reported. Kinetic isotope effect investigation clearly shows that C–H bond cleavage is the rate-determining step for PdNi-WO x /KIT-6-NH 2 . This work provides a new insight into designing low-cost and efficient heterogeneous catalysts for dehydrogenation of formic acid.