Zeolite H-ZSM-5: A Microporous Proton Conductor for the in situ Monitoring of DeNOx-SCR

2011 ◽  
Vol 1330 ◽  
Author(s):  
Thomas Simons ◽  
Ulrich Simon
Keyword(s):  
Gas Phase ◽  
Thermal Activation ◽  
Catalytic Reduction ◽  
Proton Conductor ◽  
In Situ Monitoring ◽  
Temperature Dependent ◽  
Sensor Material ◽  
Dependent Measurement ◽  
Phase Temperature

ABSTRACTImpedance spectroscopy was applied on zeolite H-ZSM 5 as a proton conducting NH3 sensor material and DeNOx-SCR (selective catalytic reduction of NOx with NH3) catalysts at the same time under SCR conditions. We show that in situ monitoring of the NH3 conversion with NOx becomes feasible when the zeolite is loaded with NH3 first and NOx is applied afterwards to the gas phase. Temperature dependent measurements allow discriminating NH3 desorption from catalytic conversion and time dependent measurement give first hints on the thermal activation of the conversion.

scholarly journals Selective Nitration of Chlorobenzene by NO2 in the Alkali Zeolite NaZSM-5

2013 ◽  
Vol 2013 ◽  
pp. 1-5
Author(s):  
Scott J. Kirkby
Keyword(s):  
Gas Phase ◽  
Room Temperature ◽  
Temperature Dependent ◽  
Reaction Conditions ◽  
Cation Site ◽  
Zeolite Lattice ◽  
Reaction Proceeds ◽  
Ft Ir ◽  
Electron Donation

Chlorobenzene was reacted with NO2, in the initially acid-free zeolite NaZSM-5, to yield para-chloronitrobenzene exclusively. The precursors were loaded sequentially into self-supporting pellets of the zeolite, contained within a stainless steel cell, from the gas phase. The reaction proceeds spontaneously at room temperature. It is, however, very temperature dependent and effectively ceases at zero degrees Celsius. The reaction was monitored in situ using FT-IR. The active nitrating agent is formed from the partial electron donation by the NO2 to the Na+ cations present in the zeolite lattice. Under the reaction conditions, chlorobenzene is not readily mobile through the pore system; thus, only the molecules adsorbed near a cation site react to form para-chloronitrobenzene.

In situ monitoring and control of multicomponent gas-phase streams for growth of GaN via MOCVD

2000 ◽  
Vol 212 (1-2) ◽  
pp. 11-20 ◽  
Author(s):  
M.C Johnson ◽  
K Poochinda ◽  
N.L Ricker ◽  
J.W Rogers Jr ◽  
T.P Pearsall
Keyword(s):  
Gas Phase ◽  
In Situ Monitoring ◽  
Monitoring And Control ◽  
Multicomponent Gas ◽  
And Control

scholarly journals Sequential Collinear Photofragmentation and Atomic Absorption Spectroscopy for Online Laser Monitoring of Triatomic Metal Species

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 533 ◽  
Author(s):  
Jan Viljanen ◽  
Kim Kalmankoski ◽  
Victor Contreras ◽  
Jaakko K. Sarin ◽  
Tapio Sorvajärvi ◽  
...  
Keyword(s):  
Atomic Absorption ◽  
Gas Phase ◽  
Absorption Spectroscopy ◽  
Atomic Absorption Spectroscopy ◽  
Limit Of Detection ◽  
In Situ Monitoring ◽  
Metal Species ◽  
Chemical Reaction Kinetics

Industrial chemical processes are struggling with adverse effects, such as corrosion and deposition, caused by gaseous alkali and heavy metal species. Mitigation of these problems requires novel monitoring concepts that provide information on gas-phase chemistry. However, selective optical online monitoring of the most problematic diatomic and triatomic species is challenging due to overlapping spectral features. In this work, a selective, all-optical, in situ gas-phase monitoring technique for triatomic molecules containing metallic atoms was developed and demonstrated with detection of PbCl2. Sequential collinear photofragmentation and atomic absorption spectroscopy (CPFAAS) enables determination of the triatomic PbCl2 concentration through detection of released Pb atoms after two consecutive photofragmentation processes. Absorption cross-sections of PbCl2, PbCl, and Pb were determined experimentally in a laboratory-scale reactor to enable calibration-free quantitative determination of the precursor molecule concentration in an arbitrary environment. Limit of detection for PbCl2 in the laboratory reactor was determined to be 0.25 ppm. Furthermore, the method was introduced for in situ monitoring of PbCl2 concentration in a 120 MWth power plant using demolition wood as its main fuel. In addition to industrial applications, the method can provide information on chemical reaction kinetics of the intermediate species that can be utilized in reaction simulations.

In-situ monitoring of transient gas phase K–Cl–S chemistry in a pilot-scale combustor

2020 ◽  
Author(s):  
Jan Viljanen ◽  
Thomas Allgurén ◽  
Yueming Wang ◽  
Xiaolong Li ◽  
Juha Toivonen ◽  
...  
Keyword(s):  
Gas Phase ◽  
Pilot Scale ◽  
In Situ Monitoring
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