Pt Supported Hierarchical ZSM-5 Zeolite as Adsorbent/Catalytic Combustion Catalyst for o-xylene Elimination

doi:10.15541/jim20180146

Abstract

Abstract:

Pt/hierarchical ZSM-5 zeolites were successfully synthesized by the steam-assisted crystallization and subsequent wetness impregnation method. Structural features were characterized by XRD, N₂ isotherm, SEM, and TEM. Its catalytic behaviors for o-xylene storage at room temperature, and catalytic combustion of stored o-xylene at elevated temperatures were evaluated. It was found that crystallinity of the product underwent a reducing tendency after introduction of mesostructure, but the mesoporosity and pore volume were remarkably increased. Compared with Pt/conventional ZSM-5 zeolite, the o-xylene adsorption capacity of Pt/hierarchical HZSM-5 was around 8 times as that of the counterpart without mesostructure. Moreover, the Pt dispersion was improved due to mesoporosity. The highly dispersed Pt nanoparticles were beneficial for catalytic combustion of o-xylene. Futhermore, Pt/hierarchical ZSM-5 showed the efficient bi-functional performance during adsorption/catalytic combustion cycling process for o-xylene. Carbon balance was kept for three cycles without secondary pollutants, showing higher adsorption capacity and better reusing stability.

Key words: Pt-based catalysts, hierarchical zeolites, VOCs, adsorption, catalytic combustion

CLC Number:

TQ174

CHEN Meng-Qiu, WANG Yu, YANG Deng-Yao, WU Hong-Juan, GUO Li-Min. Pt Supported Hierarchical ZSM-5 Zeolite as Adsorbent/Catalytic Combustion Catalyst for o-xylene Elimination[J]. Journal of Inorganic Materials, 2019, 34(2): 173-178.

Figures/Tables 8

Fig. 1 XRD patterns of Pt/mZSM-5, Pt/ZSM-5 and Pt/mAl2O3 catalysts

Fig. 2 Nitrogen isotherms of Pt/mZSM-5, Pt/ZSM-5 and Pt/mAl2O3 catalysts with inset showing the corresponding pore size distribution curves

Table 1 Textural properties of the as-synthesized catalysts

Catalyst	S_BET^a/(m²•g^-1)	S_external^b/(m²•g^-1)	S_micro^c/(m²•g^-1)	V_micro^d/(cm³•g^-1)	V_pore^e/(cm³•g^-1)	D_pore^f/(nm•g^-1·cm³)
Pt/mZSM-5	383	254	129	0.07	1.19	19.7
Pt/ZSM-5	361	170	191	0.11	0.21	2.2
Pt/mAl₂O₃	191	189	2	/	0.50	8.5

Fig. 3 SEM images of Pt/mZSM-5 (A, B), Pt/ZSM-5 (C) and Pt/mAl2O3 (D) catalysts

Fig. 4 TEM images of Pt/mZSM-5 (A), Pt/ZSM-5 (B) and Pt/mAl2O3 (C) catalysts

Fig. 5 Pt 4f XPS spectra of Pt/mZSM-5, Pt/ZSM-5 and Pt/mAl2O3 catalysts

Fig. 6 (A) Comparison of o-xylene adsorption capacity of Pt/mZSM-5, Pt/ZSM-5 and Pt/mAl2O3 catalysts; (B) Catalytic combustion of o-xylene to CO2 over Pt/mZSM-5, Pt/ZSM-5 and Pt/mAl2O3 catalysts

Fig. 7 Concentration change of CO2 and o-xylene with time during three consecutive cycling process over Pt/mZSM-5 catalyst

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