A refined design concept for sulfur-tolerant Pd catalyst supported on zeolite by shape-selective exclusion and hydrogen spillover for hydrogenation of aromatics

Journal Article · Thu Mar 11 00:00:00 EST 2021 · Journal of Catalysis

DOI:https://doi.org/10.1016/j.jcat.2021.03.001· OSTI ID:1981652

Kim, Hyun Jae ^[1]; Song, Chunshan  ^[2]

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1. Pennsylvania State Univ., University Park, PA (United States); Korea Institute of Industrial Technology, Seoul (Korea, Republic of)
2. Pennsylvania State Univ., University Park, PA (United States); The Chinese University of Hong Kong, Ma Liu Shui, Shatin (Hong Kong)

Sulfur poisoning of noble metal catalysts has been a major challenge for decades. This work demonstrates the superior sulfur tolerance of a hybrid zeolite-supported Pd catalyst for hydrogenation of tetralin containing benzothiophene. The hybrid catalyst consists of Pd supported on a large-pore acidic zeolite Y (Pd/HY) and a small-pore zeolite A without (Pd/HA) or with surface metal passivation by chemical vapor deposition of SiO₂ (SiO₂-Pd/HA) and with potassium ion exchange (SiO₂-Pd/KA). Pd/HY is very active for tetralin hydrogenation but quickly deactivates after exposure to benzothiophene at high concentration of 100 ppm sulfur. The SiO₂-coated Pd/HA shows no activity for tetralin hydrogenation, but continues to activate H₂ and serve as a source of hydrogen spillover from Pd/HA since these metal sites are protected from thiophenic sulfur due to size-selective exclusion. Adding K ion-exchanged and SiO₂-coated catalyst SiO₂-Pd/KA to Pd/HY is even more effective for enhancing sulfur tolerance, both for tetralin hydrogenation and for isomerization of cis-decalin to trans-decalin in the presence of benzothiophene. The turnover frequencies (TOF) of all the catalysts are similar at the exposed sulfur/Pd atomic ratio of around 0.5. With further increase in sulfur/Pd ratio, rapid decline in TOF was observed on Pd/HY, but SiO₂-Pd/KA + Pd/HY hybrid catalyst shows a significantly higher TOF than that over Pd/HY, even though SiO₂-Pd/KA or SiO₂-Pd/HA alone shows no TOF for tetralin hydrogenation. Even after high-dose poisoning at 400 ppm sulfur, the SiO₂-Pd/KA + Pd/HY hybrid recovered activity more quickly than SiO₂-Pd/HA + Pd/HY, while the latter in turn is much better than Pd/HY alone. These results point to the higher activity for hydrogen spillover from SiO₂-Pd/KA where Pd metal sites are protected from not only thiophenic sulfur but also inorganic sulfur H₂S by shape-selective exclusion. The present work further establishes the validity of shape-selective exclusion and hydrogen spillover in the design concept proposed for a sulfur-tolerant bimodal acidic zeolite-supported metal catalyst for hydrogenation of naphthalene [C.S. Song, Chemtech, 29 (1999) 26–30], and refines the design concept further for limiting the size of small pore in hybrid catalysts to~3 Å for restricting access of H₂S but allowing entrance of H₂. Further, this refined design concept is applicable to other supported monometallic and bimetallic catalysts.

• Research Organization: National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV, Albany, OR (United States)
• Sponsoring Organization: USDOE
• OSTI ID: 1981652
• Alternate ID(s): OSTI ID: 1868816
• Journal Information: Journal of Catalysis, Vol. 403, Issue C; ISSN 0021-9517
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Chemistry
Engineering
Shape-selective exclusion
Hydrogen spillover
Sulfur tolerance
Hydrogenation
Zeolite
Hybrid Pd catalyst