Atomically Dispersed Co²⁺ Sites Incorporated into a Silicalite-1 Zeolite Framework as a High-Performance and Coking-Resistant Catalyst for Propane Nonoxidative Dehydrogenation to Propylene

Abstract

Propane nonoxidative dehydrogenation (PDH) is a promising route to produce propylene with the development of shale gas exploration technology. Co-based catalysts with low cost and low toxicity could activate C−H effectively, but they suffer from deactivation with coke formation. In this work, a catalyst formed by incorporating highly dispersed Co sites into a Silicalite-1 zeolite framework (Co-Silicalite-1) is synthesized by a hydrothermal protocol in the presence of ammonia, which exhibits superior propane dehydrogenation catalytic performance with 0.0946 mmol C 3 H 6 •s −1 • g Co −1 and propylene selectivity higher than 98.5%. It also shows outstanding catalytic stability and coking resistance in a 3560 min time-on-stream. Combined characterization results demonstrate that the tetrahedrally coordinated Co 2+ site serves as the PDH catalytic active site, which is stabilized by Si−O units of the zeolite framework. Incorporation of Co sites into the zeolite framework could avoid the reduction of Co species to metallic Co. Moreover, the catalytic performance is improved by the enhanced propane adsorption and propylene desorption.

Tailoring Single‐Atom Platinum for Selective and Stable Catalysts in Propane Dehydrogenation

“…Cost and element strategy considerations necessitate the use of less expensive elements, such as Fe, Ni, and Co, instead of precious Pt, which is highly demanded. Due to the low activity, selectivity, and stability of non‐precious metal‐based catalysts for PDH, development is still in progress [70–73] . Recently, some alternative alloys, such as NiMo [74] and Fe 3 Ga, [75] have been reported with the help of theoretical calculations.…”

“…Due to the low activity, selectivity, and stability of non-precious metal-based catalysts for PDH, development is still in progress. [70][71][72][73] Recently, some alternative alloys, such as NiMo [74] and Fe 3 Ga, [75] have been reported with the help of theoretical calculations. These theoretical predictions have significantly aided in the material search for non-precious metal-based catalysts.…”

Advances in zeolite-supported metal catalysts for propane dehydrogenation

“…Tang and co-workers developed a catalyst using silicalite-1 as a support to incorporate atomically dispersed Co 2+ species for PDH reactions. 103 The preparation of Co-S-1 involved conventional hydrothermal synthesis using cobalt nitrate as the metal precursor in the presence of ammonia to prevent the precipitation of Co(OH) 2 . In the TEM measurements, no obvious Co nanoparticles could be observed in Co-S-1, indicating the atomic-level dispersion of Co species.…”

“…9 (a) Propane conversion and (b) propylene selectivity of various Co-based zeolite catalysts in PDH reactions at 550 °C. Reaction conditions: 0.1 g of catalyst, 5 vol% C 3 H 8 /Ar (20 mL min −1 ), and 5 vol% H 2 /Ar (20 mL min −1 ) 103. Copyright 2021, the American Chemical Society.…”

Stable co-production of olefins and aromatics from ethane over Co2+-exchanged HZSM-5 zeolite

“…38 Recently, more efforts including ours have been made to construct Fe-and, especially, Co-based catalysts using various preparation methods, and they all showed good catalytic performance in ethane and propane dehydrogenation. 19,20,[38][39][40][41][42][43][44][45][46] Therefore, it can be seen that if stable Co-O species can be constructed in acidic HZSM-5 zeolite channels, aromatics can be synthesized from light paraffins via the synergetic catalysis of Co and BAS, and Co/HZSM-5 catalysts will be a new member of the catalyst family for alkane aromatization.…”