Study On The Process And The Performance Of SCR Plate-type De-NOx Catalyst

In recent years， Nitrogen oxides (NOx) has caused serious harm to the environment,and the selective catalytic reduction (SCR) is the most effective De-NOx technology. Thecore technology for SCR is the De-NOx catalyst, and the middle temperature honeycombSCR De-NOx catalyst has been widely used in the world, but its application is hamperedunder the conditions of high ash severely, because of the poor ant-clogging and wearresistance ability. But plate-type catalyst has been successfully applied in high-ashconditions for its excellent anti-blocking, anti-wear properties. The production process forplate-type catalyst is monopolized by Japan, Europe and other countries. In recent years, thedomestic research institutes has been dedicated to the research of molding process andformulations of plate-type catalyst, but there is no plate-type catalyst production line can beused for industrial production with independent intellectual property rights in China. So theresearch for plate-type catalyst production process and formulations is particularlyimportant. In this paper, rolling molding is used to prepare plate-type catalyst, and theefficiency of rolling is higher than pressing molding.In recent years, China has been focus on solving the problem of air pollution, and theemission standards of NOx and SO2is continually increased in fumes, so the demand forhigh quality SCR catalyst is becoming larger. Because the TiO2support of catalyst accountsfor more than80%of the total content of the catalyst and the performance of domesticcatalyst supports made by different manufacturers is different, researching for catalystsupport then making evaluation parameters is very necessary. In this paper, we select threekinds of domestic carrier, HTm, PB1m and PB2m, and prepare catalysts mud bysemi-impregnation method, then these mud are ageing treated by24hours，molded byself-designed molding machine, at last, these catalysts are dried from room temperature to60℃by temperature program in five days, calcinated from60℃to610℃by temperatureprogram in33hours. The De-NOx efficiency is detected under a simulated flue gasconditions then the BET, FT-TR, XPS, Raman, TPR are used to study the performance ofdomestic catalyst supports TiO2-WO3-SO42-and the influence of TiO2-WO3-SO42-oncatalyst. At last, the relationship between WOx and VOx and the mechanism of themodification effect of WOx on VOx are analyzed.The results show: The plate-type catalyst can be prepared by the self-designedplate-type rolling molding machine and cracking phenomenon does not exist; When theBET surface area of support is too large, it is helpful to reduce the degree of polymerization of VOx, but promote the forming of isolated VOx at the same time, on the contrary, if theBET surface area of carrier is too small, the catalyst will only have a low BET surface area,so when the BET surface area of support is suitable, it is most beneficial for De-NOx;Compared with the weak B acid sites, NH3is more easily absorbed on strong B acid sites,and the electronic interaction between NH3and strong B acid sites is stronger, which willlead the intermediates not to break down easily, then hinder the progress of the reaction; Theinteraction between W6+and VOx is much stronger than that between W5+and VOx; W6+Oxwith oxygen defect structure interacts with O more easily, forming the structure of W-O-Vwith VOx, so it is interacts with VOx more easily, and beneficial for WOx modifying VOx;The lower degree of WOx on the surface of support, the better dispersion of WOx, the morebeneficial for the touch between WOx and VOx, the more conducive for WOx modifyingVOx; Modestly reducing the oxidation states of V5+=O can inhibit the oxidation of NH3andSO2; There is interaction between WOx and VOx, and they are not isolated on the surface ofthe carrier; On the one hand, WOx can promote the formation of polymeric VOx by masseffect on the catalyst surface. On the other hand, there is W-O-V on the surface of catalystbecause of the electronic effects between WOx and VOx as well as W-O-V can reduce theoxidation properties of V5+=O and inhibit the formation of highly polymer VOx.