ZnO Nanoparticles Encapsulated in Nitrogen-Doped Carbon Material and Silicalite-1 Composites for Efficient Propane Dehydrogenation

Abstract

SummaryNon-oxidative propane dehydrogenation (PDH) is an attractive reaction from both an industrial and a scientific viewpoint because it allows direct large-scale production of propene and fundamental analysis of C-H activation respectively. The main challenges are related to achieving high activity, selectivity, and on-stream stability of environment-friendly and cost-efficient catalysts without non-noble metals. Here, we describe an approach for the preparation of supported ultrasmall ZnO nanoparticles (2–4 nm, ZnO NPs) for high-temperature applications. The approach consists of encapsulation of NPs into a nitrogen-doped carbon (NC) layer in situ grown from zeolitic imidazolate framework-8 on a Silicalite-1 support. The NC layer was established to control the size of ZnO NPs and to hinder their loss to a large extent at high temperatures. The designed catalysts exhibited high activity, selectivity, and on-stream stability in PDH. Propene selectivity of about 90% at 44.4% propane conversion was achieved at 600°C after nearly 6 h on stream.

In situ formation of ZnOx species for efficient propane dehydrogenation

“…S-1_1 was exactly synthesized according to our previous study with an initial gel molar composition of 0.24 TEOS: 0.042 TPAOH: 3.67 H 2 O (ref. 31 ). S-1 supports with different concentration of OH nests were synthesized with the same procedure upon varying H 2 O/SiO 2 ratio, silica source, OH − /H 2 O ratio, crystallization temperature or adding Na + .…”

Relationship between Acidity and Activity on Propane Conversion over Metal-Modified HZSM-5 Catalysts

“…Additionally, the propane conversion approximately followed a linear relationship with the medium and strong acid (Figure 6b), except Co-HZSM-5. It is well known that particle size and dispersion of the metal phase are key factors for achieving higher catalytic activity [25]. The Co-HZSM-5 catalyst exhibited an unexpected low propane conversion of ~25%, which is due to its large Co particle size and some Co species aggregates (Figure 3).…”

“…Various metal oxides supported zeolite have been widely investigated for light alkane (i.e., methane, ethane, propane) conversion, including precious metal Pt [18,19] and transition metal Zn [20][21][22][23][24][25], Ga [26][27][28][29][30], Mo [31,32], Co [33], Zr [34][35][36] oxides, etc. Moreover, metal modification also has a potential effect on the acidity of ZSM-5.…”

Elucidating the Nature of Active Sites and Fundamentals for their Creation in Zn-Containing ZrO2–Based Catalysts for Nonoxidative Propane Dehydrogenation

“…Both isolated ZnO x species and 6 ZnO x clusters supported on SiO 2 or zeolite were reported to be active for propane dehydrogenation (PDH). [15][16][17][18] Binary ZnNbO x oxides also showed high activity and selectivity. 19 Recently, Kondratenko and colleagues [20][21][22] suggested and verified a concept for designing alternative-type catalysts on the basis of ZrO .…”