Effect of Ag loading on the adsorption/desorption properties of ZSM-5 towards toluene

Темерев, В. Л.; Vedyagin, Aleksey A.; Афонасенко, Т. Н.; Иост, К. Н.; Kotolevich, Yulia; Baltakhinov, V. P.; Цырульников, П. Г.

doi:10.1007/s11144-016-1060-3

Cited by 23 publications

(7 citation statements)

References 27 publications

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“…According to Burke et al [ 19 ], in the case of BEA (beta) zeolite, the higher SiO 2 /Al 2 O 3 ratios correspond to lower adsorption capacity in dry conditions, whereas in the presence of water, an opposite tendency is observed. The same effect was observed for the Ag-doped ZSM-5 systems [ 20 ]. Doping the zeolite with metal ions such as Ag 2+ , Fe 2+ , and Cu 2+ was shown to increase the adsorption capacity toward hydrocarbons significantly [ 17 , 21 , 22 , 23 , 24 , 25 , 26 ].…”

Section: Introductionsupporting

confidence: 76%

High-Temperature Behavior of Laser Electrodispersion-Prepared Pd/ZSM-5 Hydrocarbon Traps under CO Oxidation Conditions

et al. 2023

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Zeolites and metal-doped zeolites are now widely considered as low-temperature hydrocarbon traps to be a part of emission control systems in automobiles. However, due to the high temperature of exhaust gases, the thermal stability of such sorbent materials is of great concern. To avoid the thermal instability problem, in the present work, laser electrodispersion was used to deposit Pd particles on the surface of ZSM-5 zeolite grains (SiO2/Al2O3 = 55 and SiO2/Al2O3 = 30) to obtain Pd/ZSM-5 materials with a Pd loading as low as 0.03 wt.%. The thermal stability was evaluated in a prompt thermal aging regime involving thermal treatment at temperatures up to 1000 °C in a real reaction mixture (CO, hydrocarbons, NO, an excess of O2, and balance N2) and a model mixture of the same composition with the exception of hydrocarbons. Low-temperature nitrogen adsorption and X-ray diffraction analysis were used to examine the stability of the zeolite framework. Special attention was paid to the state of Pd after thermal aging at varied temperatures. By means of transmission electron microscopy, X-ray photoelectron spectroscopy, and diffuse reflectance UV–Vis spectroscopy, it was shown that palladium, having been initially located on the surface of zeolite, undergoes oxidation and migrates into the zeolite’s channels. This enhances the trapping of hydrocarbons and their subsequent oxidation at lower temperatures.

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Section: Introductionsupporting

confidence: 76%

High-Temperature Behavior of Laser Electrodispersion-Prepared Pd/ZSM-5 Hydrocarbon Traps under CO Oxidation Conditions

et al. 2023

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“…This is due to its large diameter pores (5.95 Å) [12] which allow for physisorption of larger molecules typical of diesel exhaust such as dodecane (4.3 Å) and toluene (5.85 Å) [13]. More recently, metal ion-exchanged zeolite hydrocarbon traps have been studied due to their increased effectiveness in adsorbing unsaturated hydrocarbons such as ethylene, propylene, and toluene via chemisorption onto the metals [10,[14][15][16][17][18][19]. Due to competition by water, alkenes are generally not appreciably adsorbed over the H + form of most zeolites under wet conditions [8].…”

Section: Introductionmentioning

confidence: 99%

Effects of CO and H2O Co-Feed on the Adsorption and Oxidation Properties of a Pd/BEA Hydrocarbon Trap

Zelinsky

Epling

2021

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Hydrocarbon traps for exhaust emissions control adsorb hydrocarbons in low temperature exhaust and release them as the exhaust warms up. In this work, a Pd/BEA hydrocarbon trap was tested under lean exhaust conditions using ethylene and dodecane as model hydrocarbons. Ethylene uptake was partially inhibited by CO and H2O when fed separately. When both were added, the loss in ethylene uptake was 90% relative to the condition with no H2O or CO. Dodecane uptake was unchanged under all conditions tested. During a temperature ramp, ethylene desorbed and was combusted to CO2 and H2O over active Pd centers. Further, oxidation light-off of dodecane generated an exotherm which caused rapid desorption of the remaining hydrocarbon species from the zeolite. For both hydrocarbons, CO co-feed led to a decreased oxidation light-off temperature, and therefore lower desorption temperature. By pretreating the catalyst in CO and H2O at 80 °C, and even after removing CO from the feed, the enhanced oxidation light-off behavior was observed. DRIFTS characterization shows that some form of oxidized Pd was reducible to Pd0 by CO at 80 °C only in the presence of H2O. Further, this reduction appears reversible by high temperature oxygen treatment. We speculate that this reduced Pd phase serves as the active site for low temperature hydrocarbon oxidation.

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“…Several technologies such as adsorption, biological degradation, and catalytic oxidation have been developed to control toluene emission [4,5]. Among these, catalytic combustion is considered one of the most efficient methods for the elimination of toluene [6,7].…”

Section: Introductionmentioning

confidence: 99%

Insights into the Pyrolysis Processes of Ce-MOFs for Preparing Highly Active Catalysts of Toluene Combustion

Sun

et al. 2019

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Metal organic frameworks (MOFs) have recently been used as precursors of the catalysts for the combustion of volatile organic compounds (VOCs). In the present work, three kinds of CeO 2 catalysts were successfully synthesized from Ce-MOF-808, Ce-BTC, and Ce-UiO-66, with specific topological structures and coordinate environments. Catalysts with small particle size, stacking mode, and structural defects could be created by pyrolysis of Ce-MOFs, which affects the activity in the toluene combustion significantly. Raman spectra, XPS, and OSC studies were performed to reveal the formation of defect sites. The thermal redox properties were determined by H 2 -TPR. Catalytic activity tests were conducted on the toluene combustion, and CeO 2 -MOF-808 showed the best catalytic performance (T90 = 278 • C) due to its having the largest specific surface area, abundant active surface oxygen species, and low-temperature reducibility.

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Effect of Ag loading on the adsorption/desorption properties of ZSM-5 towards toluene

Cited by 23 publications

References 27 publications

High-Temperature Behavior of Laser Electrodispersion-Prepared Pd/ZSM-5 Hydrocarbon Traps under CO Oxidation Conditions

High-Temperature Behavior of Laser Electrodispersion-Prepared Pd/ZSM-5 Hydrocarbon Traps under CO Oxidation Conditions

Effects of CO and H2O Co-Feed on the Adsorption and Oxidation Properties of a Pd/BEA Hydrocarbon Trap

Insights into the Pyrolysis Processes of Ce-MOFs for Preparing Highly Active Catalysts of Toluene Combustion

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