scholarly journals OPTIMIZATION OF THE SELECTIVE CATALYTIC REDUCTION OF NO IN DIESEL EXHAUST OVER CU-ZN/ZSM-5 CATALYST USING CENTRAL COMPOSITE DESIGN

2010 ◽  
Vol 11 (1) ◽  
pp. 106-122 ◽  
Author(s):  
Ahmad Zuhairi Abdullah ◽  
Hamidah Abdullah ◽  
Subhash Bhatia ◽  
Babak Salamatinia ◽  
Noraini Razali
Keyword(s):  
Central Composite Design ◽  
Selective Catalytic Reduction ◽  
No Reduction ◽  
Bimetallic Catalyst ◽  
Catalytic Reduction ◽  
Exchange Process ◽  
Space Velocity ◽  
Operating Conditions ◽  
Process Conditions ◽  
Central Composite

The optimization of the operating conditions in nitric oxide (NO) selective catalytic reduction (SCR) process over Cu-Zn/ZSM-5 bimetallic catalyst using combined Response Surface Methodology (RSM) and Central Composite Design (CCD) is reported. A bimetallic catalyst containing 6 wt. % Cu and 8 wt. % Zn was prepared through a combined impregnation and ion-exchange process. The process conditions investigated were temperature (300 -400 ?C), NO concentration (900-2,000 ppm) and iso-butane (reductant) concentration (900 - 2,000 ppm). The weight hourly space velocity (WHSV) was fixed at 13,000 h-1. Cu-Zn/ZSM-5 catalyst proved its potential for the SCR process. Statistical analyses showed that the NO reduction was affected by all the operating conditions with the temperature as the most dominant one. Based on the experimental design, a second order mathematical model was successfully developed and satisfactory fitting to the experimental data was demonstrated. Interactions between variables were also analyzed at 99.99 % confidence level. The optimum conditions obtained were 624 ppm for the NO concentration, 2,440 ppm for the iso-butane concentration and 389 °C for the reaction temperature to give a corresponding NO reduction of  96.13 %.

scholarly journals Kinetics of Selective Catalytic Reduction of Nitric Oxide over Pt-Cu-Zsm5 Catalyst

1970 ◽  
Vol 4 (1) ◽  
Author(s):  
Ismail Mohd Saaid ◽  
Abdul Rahman Mohamed and Subhash Bhatia
Keyword(s):  
Nitric Oxide ◽  
Selective Catalytic Reduction ◽  
Active Sites ◽  
No Reduction ◽  
Bimetallic Catalyst ◽  
Catalytic Reduction ◽  
Covalent Bond ◽  
Reaction Parameters ◽  
Heterogeneous Model ◽  
Kinetics Of

Kinetics for the selective catalytic reduction (SCR) of nitric oxide (NO) using i-C4H10 as the reducing agent over Pt-Cu-ZSM5 has been investigated in the temperature range of 200 ?C – 450 oC. Langmuir-Hinshelwood-Hougen-Watson model was proposed for kinetics of the reaction and reaction parameters were evaluated.  The heat of adsorption of NO was found to be considerably high, attributed to strong covalent bond between NO gas molecules and metal active sites.  Using reaction parameters obtained from the experiment, the heterogeneous model could form a good correlation between experimental and simulated values of NO reduction. Key Words: Reaction kinetics, Selective catalytic reduction, NO reduction, Bimetallic catalyst, H-ZSM-5 zeolite.

Mechanistic insight into the influence of O2 on N2O formation in the selective catalytic reduction of NO with NH3 over Pd/CeO2 catalyst

2021 ◽  
Author(s):  
Liping Sheng ◽  
Songda Li ◽  
Zhaoxia Ma ◽  
Fei Wang ◽  
Hu He ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
No Reduction ◽  
Catalytic Reduction ◽  
Temperature Dependent ◽  
N2o Formation ◽  
Reduction Of No ◽  
Mechanistic Insight ◽  
Insight Into

O2 greatly affected the pathway for NO reduction over the Pd/CeO2 catalyst and resulted in a temperature-dependent NH3-SCR performance and formation of N2O.

A Ce-Zr-Ti Oxide Catalyst for Selective Catalytic Reduction of NO with Ammonia

2014 ◽  
Vol 535 ◽  
pp. 709-712
Author(s):  
Ye Jiang ◽  
Yan Yan ◽  
Shan Bo Huang ◽  
Xiong Zhang ◽  
Xin Wei Wang ◽  
...  
Keyword(s):  
High Activity ◽  
Selective Catalytic Reduction ◽  
Oxide Catalyst ◽  
Catalytic Reduction ◽  
Space Velocity ◽  
Impregnation Method ◽  
Reduction Of No ◽  
No Conversion ◽  
Temperature Range ◽  
Ti Oxides

A Ce-Zr-Ti oxide catalyst was prepared by an impregnation method and tested for the selective catalytic reduction of NO with NH3. The Ce-Zr-Ti oxide catalyst exhibited high activity and more than 95% NO conversion was obtained within the temperature range 300-500 °C at the high gas hourly space velocity of 50,000 h-1. The addition of Zr improved the activity of Ce-Ti oxides especially at higher reaction temperatures and their resistance to SO2.

scholarly journals Insights into the promotion role of phosphorus doping on carbon as a metal-free catalyst for low-temperature selective catalytic reduction of NO with NH3

RSC Advances ◽  
2020 ◽  
Vol 10 (22) ◽  
pp. 12908-12919
Author(s):  
Weifeng Li ◽  
Shuangling Jin ◽  
Rui Zhang ◽  
Yabin Wei ◽  
Jiangcan Wang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
No Reduction ◽  
Catalytic Reduction ◽  
Carbon Aerogels ◽  
Phosphorus Doping ◽  
Reduction Of No ◽  
Metal Free

P species can effectively enhance the catalytic activity of carbon aerogels for NO reduction at low temperature.

Modelling and parametric investigation of NOx reduction by oxidation precatalyst-assisted ammonia-selective catalytic reduction

2009 ◽  
Vol 223 (9) ◽  
pp. 1193-1206 ◽  
Author(s):  
S-C Jung ◽  
W-S Yoon
Keyword(s):  
Selective Catalytic Reduction ◽  
Low Temperatures ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Volume Ratio ◽  
Kinetic Scheme ◽  
Space Velocity ◽  
Gas Temperature ◽  
Scr System ◽  
Very High

Nitrogen oxide (NO x) reduction by the selective catalytic reduction (SCR) system assisted by an oxidation precatalyst is modelled and analytically investigated. The Langmuir—Hinshelwood SCR kinetic scheme with vanadium-based catalyst and ammonia (NH3) reductant in conjunction with the NO—NO2 conversion reaction over a platinum-based catalyst is used. The effects of the ratio of the oxidation precatalyst to the SCR monolith volume, the gas temperature, the space velocity, and the NH3-to-NO x concentration ratio on the de-NO x performance are parametrically examined. The oxidation precatalyst promotes NO x conversion at low temperatures. At intermediate temperatures, the NO x reduction is either activated or deactivated with increase in the space velocity. A higher oxidation precatalyst-to-SCR monolith volume ratio tends to promote the NO x reduction of higher space velocities. At high temperatures, the de-NO x efficiency is very high and insensitive to the space velocity. The NO x conversion efficiency depends on the NH3-to-NO x ratio at low temperatures.

Application of the central composite design for condition optimization for semi-aerobic landfill leachate treatment using electrochemical oxidation

2010 ◽  
Vol 61 (5) ◽  
pp. 1257-1266 ◽  
Author(s):  
Soraya Mohajeri ◽  
Hamidi Abdul Aziz ◽  
Mohamed Hasnain Isa ◽  
Mohammad Ali Zahed ◽  
Mohammed J. K. Bashir ◽  
...  
Keyword(s):  
Reaction Time ◽  
Central Composite Design ◽  
Electrochemical Oxidation ◽  
Current Density ◽  
Landfill Leachate ◽  
Electrolyte Concentration ◽  
Process Conditions ◽  
Leachate Treatment ◽  
Condition Optimization ◽  
Central Composite

In the present study, Electrochemical Oxidation was used to remove COD and color from semi-aerobic landfill leachate collected from Pulau Burung Landfill Site (PBLS), Penang, Malaysia. Experiments were conducted in a batch laboratory-scale system in the presence of NaCl as electrolyte and aluminum electrodes. Central composite design (CCD) under Response surface methodology (RSM) was applied to optimize the electrochemical oxidation process conditions using chemical oxygen demand (COD) and color removals as responses, and the electrolyte concentrations, current density and reaction time as control factors. Analysis of variance (ANOVA) showed good coefficient of determination (R2) values of >0.98, thus ensuring satisfactory fitting of the second-order regression model with the experimental data. In un-optimized condition, maximum removals for COD (48.77%) and color (58.21%) were achieved at current density 80 mA/cm2, electrolyte concentration 3,000 mg/L and reaction time 240 min. While after optimization at current density 75 mA/cm2, electrolyte concentration 2,000 mg/L and reaction time 218 min a maximum of 49.33 and 59.24% removals were observed for COD and color respectively.

Synergetic Effects between Al2O3 and HZSM-5 for NO Reduction by CH4

2011 ◽  
Vol 214 ◽  
pp. 364-368
Author(s):  
Li Li Ren ◽  
Xiao Mei Pan
Keyword(s):  
Catalytic Activity ◽  
Selective Catalytic Reduction ◽  
No Reduction ◽  
Catalytic Reduction ◽  
Synergetic Effect ◽  
Separate Component ◽  
Reduction Of No ◽  
Synergetic Effects

Three different kinds of Al2O3 have been added to HZSM-5 for improving its activity towards selective catalytic reduction of NO with CH4 in the presence of excess of oxygen. Higher conversions of NO have been observed for all of the three mixed catalysts, the conversion of which were also found to be higher than that of each separate component of the catalysts. It was concluded that there exists a synergetic effect between Al2O3 and HZSM-5. The addition of Al2O3 can improve the catalytic activity of HZSM-5 by inhibiting the decomposing of NO2 to NO and accelerating the activation of methane. Adsorbed NO2 is then reduced by the activated methane or the intermediates formed from activated methane to N2 over the Brønsted site of zeolite.

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