稀土尾矿基蜂窝状脱硝催化剂的成型及性能检测

Forming and Performance Testing of Honeycombed Denitrification Catalyst Based on Rare Earth Tailings

以白云鄂博稀土尾矿粉末为研究原料,通过Solidworks绘制,CoLiDO桌面3D打印机打印出成型模具,采用模具压制法将组成物料成型为蜂窝状脱硝催化剂。考察了不同粘结剂和不同物料配比对稀土尾矿基蜂窝状脱硝催化剂影响,并对成型催化剂进行维氏硬度仪、万能试验机测试和BET,SEM-EDS,XRD及TG等表征分析。研究结果表明:磷酸二氢铝溶液为最佳的粘结剂且最佳的物料配比为:稀土尾矿基粉末:拟薄水铝石粉末∶黏土=2∶4∶3;成型的蜂窝状脱硝催化剂在反应温度800℃时脱硝催化活性高达88.60%,与传统粘结剂硅酸钠溶液相比,选用磷酸二氢铝溶液结合拟薄水铝石粉末所成型的蜂窝状脱硝催化剂在最佳工况下脱硝活性提升30%以上,且具有抗硫性与脱硝稳定性;在可以保证机械性能良好的情况下,原本比表面小、表面光滑的稀土尾矿经成型后转化为无规则、多孔状蜂窝体(成型样比表面积最大为10.28m^(2)·g^(-1)),因两种铝源在500℃焙烧熔化为γ-Al_(2)O_(3),导致稀土尾矿在γ-Al_(2)O_(3)下活位点暴露,放大其脱硝性能;成型样在经焙烧后会产生有助于脱硝反应进行的CeO_(2)和Fe_(2)O_(3),且在500℃焙烧分解产生气体(CO_(2)),逸出气体对胚体造成内应力,产生的气孔使蜂窝状柱体的孔隙率增大。

BayanObo rare earth tailings were used as raw materials,the model through Solidworks was drawn,and the mold through Co Li DO desktop 3D printer wasa printed.A honeycombed denitration catalyst was prepared from the raw material by means of mould pressing.The effect of different binder and material ratio on the honeycombed denitration catalyst of rare earth tailings was investigated.The molded catalyst was tested by Vickers hardness,universal testing machine,BET,SEM-EDS,XRD and TG.The results showed that aluminum dihydrogen phosphate solution is the best binder,and the best ratio of rare earth tailings powder,pseudo-boehmite powder and clay is 2∶4∶3.Under the condition of reaction temperature 800℃,the rate of honeycombed denitration catalyst is 88.60%.Compared with the traditional binder sodium silicate solution,the honeycombed denitration catalyst made of aluminum dihydrogen phosphate solution and pseudo-boehmite powder can increase the denitration activity by more than 30%under the optimal conditions.Meanwhile,it has good sulfur resistance and stability.Under the condition of good mechanical properties,the rare earth tailings with small specific surface area and smooth surface are transformed into irregular,porous honeycomb bodies(the maximum specific surface area of molded samples is 10.28 m^(2)·g^(-1)).The reason is that the two aluminum sources melt intoγ-Al_(2)O_(3) after roasting at 500℃,which leads to the exposure of the live site of the rare earth tailings underγ-Al_(2)O_(3),and enhances its denitration performance.The formed sample produces CeO_(2) and Fe_(2)O_(3) after roasting,which contribute to the denitration reaction.Meanwhile,the formed sample will decompose to produce gas(CO_(2)) after roasting at 500℃,the escaping gas causes internal stress on the embryo body,and the porosity of the honeycomb cylinder increases.