Abstract
Selective catalytic reduction (SCR) technology is the most widely used flue gas denitration technology at present. The stability of a catalyst is the main factor limiting the development of this technology. In this study, an environmentally friendly and highly efficient NH3-SCR catalyst was prepared by coprecipitation method from acidolysis residue of industrial waste and tourmaline. We found that the addition of tourmaline has an important impact on the denitration activity of the catalytic material. The NOx conversion exceeded 97% at 200 °C with the dosage of 10% tourmaline, which is about 7% higher than that without doping. The improvement of catalytic performance was mostly attributed to the permanent electrodes of tourmaline, which effectively promotes the dispersion of MnOx/TiO2 catalytic materials, increases the number of acidic sites and changes the valence distribution of manganese ions in products, which speeds up the diffusion of protons and ions, resulting in the acceleration of redox reaction. These as-developed tourmaline-modified MnOx/TiO2 materials have been demonstrated to be promising as a new type of highly efficient low-temperature NH3-SCR catalyst.
Highlights
Nitrogen oxides (NOs) are the primary source of environmental problems such as photochemical smog and atmospheric acid deposition, the removal of NOx is a matter of great urgency
It was discovered that the major reasons for the poor stability of denitration are the integrity of crystallinity, the decrease of specific surface area and the lessening of the acidic sites number after long-term
In consideration of the above problems, this paper considers using non-metallic mineral tourmaline to compound with this kind of catalytic material, and explores the effect of tourmaline on its catalytic activity
Summary
Nitrogen oxides (NOs) are the primary source of environmental problems such as photochemical smog and atmospheric acid deposition, the removal of NOx is a matter of great urgency. As one of the principal sources of nitrogen oxides emission, cement kilns frequently adopt selective catalytic reduction (SCR) technology to effectively abate flue gas [1]. Catalytic materials are the kernel of SCR technology, selecting a suitable catalyst could effectively increase the denitration efficiency and reduce costs [2]. Previous research of the project group adopted acid hydrolysis residue from the titanium dioxide industry, produced by the sulfuric acid process as raw material, and prepared the MnOx /TiO2 catalyst via co-precipitation method. The initial catalytic activity of the catalyst reaches up to 91%, but the stability is relatively poor; after long-term denitration at 200 ◦ C for ten hours, the catalytic activity drops below 80%. It was discovered that the major reasons for the poor stability of denitration are the integrity of crystallinity, the decrease of specific surface area and the lessening of the acidic sites number after long-term
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