Hydrophobic Modification of ZSM-5-Encapsulated Uniform Pt Nanoparticles for Catalytic Oxidation of Volatile Organic Compounds

Abstract

Zeolite-supported noble-metal catalysts are considered to be one of the most promising materials to achieve complete oxidation of volatile organic compounds (VOCs). However, noble metals tend to agglomerate under synthesis/reaction conditions and are easily poisoned by halogen compounds, resulting in reduced catalytic activity and stability. Herein, Pt nanoparticles (∼2 nm) encapsulated in ZSM-5 catalysts (Pt/Z-En) with a series of Si/Al molar ratios were prepared by a one-pot synthesis strategy using tetraammineplatinum nitrate as the metal precursor, and their catalytic performance for oxidation of VOCs was explored. The characterizations showed that the Pt–zeolite interaction and metal dispersion were significantly enhanced after encapsulation in zeolite. In the VOC (toluene as a model reactant) oxidation experiment, Pt/Z-En possessed higher catalytic activity compared with catalysts prepared by the impregnation method (Pt/Z-Im). In addition, hydrophobic modification by increasing the Si/Al molar ratio facilitated the adsorption of toluene and restricted the adsorption of halogen compounds (1,2-dichloroethane) on the catalyst, which further promoted catalytic activity and stability. The Pt/Z-200-En catalyst with a Si/Al molar ratio of 200 gave the optimum catalytic performance, with a toluene conversion of 98% at a temperature as low as 214 °C with long-term stability.

CeO2 Nanorods Decorated with Pt Nanoparticles as Catalysts for Oxidative Elimination of Formaldehyde

“…Although transition-metal oxides like MnO 2 and CeO 2 exhibit HCHO oxidation activity, the performance is too low at room temperature . Till date, noble metal nanoparticles, especially Pt, are the most active for HCHO oxidation at room temperature. , Ji and co-workers developed Pt nanoparticles supported on ZSM-5 and ZnO-modified TiO 2 arrays, over which 95% HCHO conversions were obtained at 303 K for 100 h. , 0.8% Pt/Fe 3 O 4 catalyst completely oxidized 1 ppm HCHO/air at a space velocity of 150 L/(gh) and converted 70% HCHO of 100 ppm HCHO/air at a higher space velocity of 600 L/(gh) at room temperature …”

“…5 Till date, noble metal nanoparticles, especially Pt, are the most active for HCHO oxidation at room temperature. 6,7 Ji and co-workers developed Pt nanoparticles supported on ZSM-5 and ZnOmodified TiO 2 arrays, over which 95% HCHO conversions were obtained at 303 K for 100 h. 8,9 0.8% Pt/Fe 3 O 4 catalyst completely oxidized 1 ppm HCHO/air at a space velocity of 150 L/(gh) and converted 70% HCHO of 100 ppm HCHO/ air at a higher space velocity of 600 L/(gh) at room temperature. 2 Numerous studies have reported the influences of support shapes for reactions and revealed the dependence of catalytic performance on the exposed crystal planes of the shaped support.…”

Principle on Selecting the Coordination Ligands of Palladium Precursors Encapsulated by Zeolite for an Efficient Purification of Formaldehyde at Ambient Temperature

“…20 For example, Zhu et al prepared Pt NPs encapsulated in ZSM-5 catalysts (Pt/Z-En) with a series of Si/ Al molar ratios involving one-pot synthesis method and using tetraammineplatinum nitrate as the metal precursor. 21 The results confirmed that the Pt−zeolite interaction and metal dispersion were significantly enhanced after metal encapsulation in zeolite. Chai et al have developed an efficient in situ strategy for encapsulation of Pd nanoparticles within MFI-type zeolites using (3-mercaptopropyl)trimethoxysilane as a ligand.…”

“…Different ligands, such as ammonia, ethylenediamine, and mercaptosilane, were previously introduced to the synthesis mixture . For example, Zhu et al prepared Pt NPs encapsulated in ZSM-5 catalysts (Pt/Z-En) with a series of Si/Al molar ratios involving one-pot synthesis method and using tetraammineplatinum nitrate as the metal precursor . The results confirmed that the Pt–zeolite interaction and metal dispersion were significantly enhanced after metal encapsulation in zeolite.…”

Total oxidation of benzene over cerium oxide-impregnated two-dimensional MWW zeolites obtained by environmental synthesis using Brazilian rice husk silica agro-industrial waste

“…Zeolites with MFI, FAU and BEA codes-supported metal catalysts are one of the most promising materials to achieve oxidation of air pollutants [6][7][8][9]. These solids have well-established applications as supports and catalysts because of their beneficial properties including, a high specific surface that promotes the high dispersion of the active sites and well-defined pore structure with channels and cavities able to encapsulate nanoparticles (NPs) and reduce sintering effects, ion exchange ability, and thermal and hydrothermal stability [10].…”