Effect of heating method on NO&lt;sub&gt;x&lt;/sub&gt; decomposition on H&lt;sub&gt;3&lt;/sub&gt;PW&lt;sub&gt;12&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt;0•6H&lt;sub&gt;2&lt;/sub&gt;O

L Cheng,R Wang,X Zhang

doi:10.4314/bcse.v27i2.13

Abstract

The thermal decomposition of nitrogen oxides (NOx) on phosphotungstic acid (H3PW12O40·6H2O or HPW) by two different heating methods is compared. Infra-red (IR) and X-ray diffraction (XRD) measurements are conducted to investigate the decomposition mechanism. Both heating methods, i.e. heating from 30 °C to 450 °C at a rate of 150 °C/min (“rapid heating”) and heating at a constant temperature of 450 °C (“constant-temperature heating”) lead to an actual, considerably high heating rate. Compared with rapid heating, however, constant-temperature heating results in enhanced N2 conversion (21.8%). Furthermore, the catalyst can be reused after decomposition at constant-temperature heating, while its performance quickly degrades after decomposition via rapid heating. KEY WORDS: Nitrogen oxides, Heteropoly acids, Decomposition, Heating Bull. Chem. Soc. Ethiop. 2013, 27(2), 281-287.DOI: http://dx.doi.org/10.4314/bcse.v27i2.13

Highlights

Nitrogen oxides (NOx) are considered as primary atmospheric pollutants because they cause environmental threats such as acid rain, photochemical smog, ozone layer depletion, and even global warming, and have a detrimental effect on human health, provoking lung infections and respiratory allergies [1,2,3,4]
It is of key interest to develop a heating method that is based on a high heating rate yet does not surpass the target temperature
To avoid degradation of the catalyst by exceeding the oven’s target temperature, we have explored a novel constant-temperature heating method and compared it with the traditional rapid-heating method for NOx decomposition

Summary

Introduction

Nitrogen oxides (NOx) are considered as primary atmospheric pollutants because they cause environmental threats such as acid rain, photochemical smog, ozone layer depletion, and even global warming, and have a detrimental effect on human health, provoking lung infections and respiratory allergies [1,2,3,4]. Great efforts have been taken to reduce NOx, and various technologies to control NOx emissions have been researched These technologies can be classified into two major categories, based on whether reduction is employed or not: catalytic reduction and catalytic decomposition. The most commonly studied catalysts for NOx catalytic decomposition include noble metals, metallic oxides, perovskites and perovskite-type oxides, ion-exchanged ZSM-5, heteropolyacids (HPAs), and hydrotalcites [5]. Among these catalysts, HPAs have attracted considerable attention owing to their acidity, redox properties, and pseudo-liquid phase [6]. It is of key interest to develop a heating method that is based on a high heating rate yet does not surpass the target temperature

Methods

Results

Conclusion