Low-temperature selective catalytic reduction of NO with propylene in excess oxygen over the Pt/ZSM-5 catalyst

Zhang, Zhixiang; Chen, Mingxia; Jiang, Zhi; Shangguan, Wenfeng

doi:10.1016/j.jhazmat.2011.07.038

Cited by 22 publications

(13 citation statements)

References 20 publications

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“…There have been many investigations of the kinetics and reaction mechanism of NO oxidation over metal-containing zeolites, particularly with copper and iron species [19][20][21]. Less attention has been given to the high-temperature NO oxidation mechanism over materials without transition metals.…”

Section: +5 →+6mentioning

confidence: 99%

Oxidation of zeolite acid sites in NO/O2 mixtures and the catalytic properties of the new site in NO oxidation

Loiland

Lobo

2015

Journal of Catalysis

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The NO oxidation reaction kinetics over a number of zeolite structures were investigated at temperatures above 423 K using plug-flow microreactors and in situ FTIR spectroscopy. Fast catalytic NO oxidation rates (up to 1,000 ×) are observed over Hand Na-exchanged zeolite frameworks (BEA, MFI, and CHA) at temperatures above 423 K with respect to the gas-phase reaction. NO oxidation rates increase with temperature over Hand Na-zeolites, while siliceous zeolites display little activity. Activation energies scale in the order of CHA < MFI < BEA (40.8-55.5 kJ mol-1), and application of transition state theory shows that the formation of the activated complex is an enthalpically controlled process that benefits from smaller zeolite pore size. In all samples, rates are proportional to NO and O 2 concentrations, in contrast to low temperature catalytic rates (J. Catal., 2014, 311), which are second order in NO and first order in O 2. This difference indicates that a new reaction mechanism is operative above 423 K. In-situ FTIR studies reveal that NO + coordinated at framework sites in the zeolite pores (Si-O-(NO +)-Al) play a direct role in the catalysis, and they also reveal that the NO oxidation rate is proportional to the amount of NO + present in the sample. Furthermore, it is found that NO + is in equilibrium with gas phase NO and that desorption of NO + (as NO) yields an oxidized acid site (Si-O•-Al). No evidence of NO + formation is observed over the siliceous zeolite samples. A working model of the reaction mechanism for the high-temperature NO oxidation reaction is proposed for acidic zeolites that is consistent with the observed form of the rate equation and the observed NO + reaction intermediate.

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Section: +5 →+6mentioning

confidence: 99%

Oxidation of zeolite acid sites in NO/O2 mixtures and the catalytic properties of the new site in NO oxidation

Loiland

Lobo

2015

Journal of Catalysis

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“…After calcination at 300 • C and 700 • C for 2 h in O 2 atmosphere, the morphology and crystallinity were still well maintained (as shown in Figure S2). A very weak diffraction peak of the (111) lattice plane belonging to Pt at 2θ = 39.78 • can be discriminated from the XRD pattern of the Pt@S-1 sample, but the small peak disappeared after calcination at 300 • C in O 2 atmosphere, i.e., no diffraction peak of the platinum (111) crystal plane appeared in the XRD pattern of the Pt@S-1-300O 2 sample, and no other diffraction peaks belonging to PtO 2 , which showed that low temperature oxygen calcination can reduce the diameter of nanoparticles and increase the dispersion of platinum species, so that X-ray diffraction was not sufficient to detect the presence of platinum species in the case of same loading amounts of platinum [29]. This conclusion can be confirmed again by transmission electron microscopy (TEM) and CO adsorption.…”

Section: Phase Compositionmentioning

confidence: 97%

In Situ Encapsulated Pt Nanoparticles Dispersed in Low Temperature Oxygen for Partial Oxidation of Methane to Syngas

Wang

Ding

et al. 2019

Catalysts

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Highly dispersed ultra-small Pt nanoparticles limited in nanosized silicalite-1 zeolite were prepared by in situ encapsulation strategy using H2PtCl6·6H2O as a precursor and tetrapropylammonium hydroxide as a template. The prepared Pt@S-1 catalyst was characterized by X-ray diffraction (XRD), inductively coupled plasma (ICP), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), N2 adsorption-desorption, CO adsorption, and TGA techniques and exhibited unmatched catalytic activity and sintering resistance in the partial oxidation of methane to syngas. Strikingly, Pt@S-1 catalyst with further reduced size and increased dispersibility of Pt nanoparticles showed enhanced catalytic activity after low-temperature oxygen calcination. However, for Pt/S-1 catalyst, low-temperature oxygen calcination did not improve its catalytic activity.

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“…Nitrogen oxides (NO and NO 2 ), released from stationary and mobile source exhaust, have generated a series of serious environmental issues, such as photochemical smog, acid rain, greenhouse effects, and ozone depletion. − Selective catalytic reduction with NH 3 (NH 3 -SCR) is currently regarded to be one of the most effective strategies to reduce NO x emissions. , Meanwhile, V 2 O 5 –MoO 3 (WO 3 )/TiO 2 has been the extensively employed and currently commercial NH 3 -SCR catalyst. , However, several disadvantages are still present in this system, which considerably limit its further utilization in practical applications, for instance, the toxicity of vanadium species, the high operation temperature, the low specific surface area of TiO 2 , and so forth. − Furthermore, the temperature of emitted NO x from stationary coal-fired plants and boilers is generally lower than 250 °C, yet the V 2 O 5 –WO 3 (MoO 3 )/TiO 2 catalyst is not effective for the abatement of exhaust smoke NO x at the so-low temperature region. Therefore, it is necessary and imperative to develop environmentally friendly NH 3 -SCR catalysts with excellent low-temperature activity for the conversion of NO x .…”

Section: Introductionmentioning

confidence: 99%

Mechanochemical Synthesis of Highly Porous CeMnO_x Catalyst for the Removal of NO_x

Cheng

Tan

Ren

et al. 2019

Ind. Eng. Chem. Res.

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Tailoring the pore structure is a straightforward and effective strategy to regulate the catalytic activity of catalysts in heterogeneous catalysis reactions but remain a challenge. Herein, we present a low-cost, facile, and large-scale mechanochemical nanocasting strategy between cerium salt and manganese salt that enables solvent-free and rapid synthesis of porous CeMnO x oxide with a high specific surface area, rich chemisorbed oxygen species, Mn4+, and acidity, as well as improved reducibility. Moreover, this kind of catalyst shows exceptionally high low-temperature activity for the selective catalytic reduction of NO x with ammonia (NH3-SCR). It achieves almost 100% NO x conversion at 150 °C, which is much lower than that of its bulk CeMnO x counterpart constructed by the sol–gel method. It is expected that this technology may open up new opportunities for fabricating a number of advanced porous materials with exceptional catalytic activity for the environmental catalysis field.

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Low-temperature selective catalytic reduction of NO with propylene in excess oxygen over the Pt/ZSM-5 catalyst

Cited by 22 publications

References 20 publications

Oxidation of zeolite acid sites in NO/O2 mixtures and the catalytic properties of the new site in NO oxidation

Oxidation of zeolite acid sites in NO/O2 mixtures and the catalytic properties of the new site in NO oxidation

In Situ Encapsulated Pt Nanoparticles Dispersed in Low Temperature Oxygen for Partial Oxidation of Methane to Syngas

Mechanochemical Synthesis of Highly Porous CeMnO_x Catalyst for the Removal of NO_x

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Low-temperature selective catalytic reduction of NO with propylene in excess oxygen over the Pt/ZSM-5 catalyst

Cited by 22 publications

References 20 publications

Oxidation of zeolite acid sites in NO/O2 mixtures and the catalytic properties of the new site in NO oxidation

Oxidation of zeolite acid sites in NO/O2 mixtures and the catalytic properties of the new site in NO oxidation

In Situ Encapsulated Pt Nanoparticles Dispersed in Low Temperature Oxygen for Partial Oxidation of Methane to Syngas

Mechanochemical Synthesis of Highly Porous CeMnOx Catalyst for the Removal of NOx

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Mechanochemical Synthesis of Highly Porous CeMnO_x Catalyst for the Removal of NO_x