混合氧化物脱硝催化剂制备基础研究
发布时间：2018-12-13 19:38
【摘要】：目前在国内外多种烟气脱硝方法中SCR法是最成熟的烟气脱硝技术。然而对于这一技术，我国起步较晚，特别是在其核心技术催化剂的制备上还没有自主知识产权，因此要更为成熟的运用SCR技术，我国必须自主研发SCR脱硝催化剂。催化剂作为SCR技术的核心，在我国具有广阔的市场需求，且其在SCR脱硝系统中的投资占到总投资的1/3，而现行的商业催化剂价格较高，，这会直接导致脱硝技术成本的增加。因此，本课题选择了某价格低廉的工业副产品混合氧化物(以下简称M)为主要原料进行SCR-氨法脱硝催化剂的实验室制备研究工作，即在对M表面性质进行分析和研究的基础上，考察了粘结剂对该混合氧化物成型性能的影响，为实现混合氧化物脱硝催化剂的成型奠定基础。 本文利用XRF、XRD、金相显微镜等表征手段对混合氧化物的物化性质进行了研究，并结合抗压强度、BET比表面积、NH_3-TPD等表征方法考察了有机粘结剂（聚乙烯醇、甲基纤维素和聚丙烯酰胺）、无机粘结剂（氧化铝、皂土）及有机-无机混合粘结剂对混合氧化物成型性能的影响。 结果表明原混合氧化物比表面积为1.485m~2/g，其比表面积较小，不利于活性成分的负载，需在后续研究中考虑其比表面积对制备催化剂活性的影响。综合各实验数据，选定在后续实验中所用混合氧化物的条件：以干法球磨45min （1800r/min）、筛分大于80目的混合氧化物为主要原料。通过各粘结剂成型混合氧化物的过程可知，有机粘结剂对混合氧化物成型时，浆料流动性较好，采用造粒机压片、制丸等过程更易实施，其中以MC更甚，在选用混合粘结剂对混合氧化物成型时，也以有机粘结剂的成型特点占主导作用。仅以有机粘结剂对混合氧化物成型时，得到的成型氧化物抗压强度均不高，而以无机粘结剂成型得到的成型氧化物抗压强度较高，皂土最高抗压强度达到1.846MPa，与单独使用有机粘结剂成型相比，无机粘结剂的添加可使抗压强度有显著提高。采用有机粘结剂对混合氧化物成型时，成型氧化物BET比表面积与粘结剂分子量大小有关，分子量太大，在焙烧过程中会产生大量气体形成大量气孔，引起其孔结构塌陷，进而导致成型物比表面积有所下降。选用无机粘结剂成型时比表面积较大，与仅用有机粘结剂成型相比，混合粘结剂成型得到的成型氧化物BET比表面积有明显提高。通过几组粘结剂对混合氧化物成型得到的最佳抗压强度的成型物比表面积与抗压强度对比说明，该混合氧化物成型得到的成型物的抗压强度与比表面积之间不存在明显的正相关关系。粘结剂对混合氧化物成型得到的成型氧化物对氨气的吸附性质相似，NH_3吸附量和表面酸量均不大，成型氧化物对NH_3的吸附量和表面酸性与其抗压强度间没有明显的正相关关系。
[Abstract]:At present, SCR method is the most mature technology of flue gas denitrification among many flue gas denitrification methods at home and abroad. However, for this technology, China started late, especially in the preparation of its core technology catalyst has not yet independent intellectual property rights, so in order to more mature use of SCR technology, our country must independently develop SCR denitrification catalyst. As the core of SCR technology, catalyst has broad market demand in China, and its investment in SCR denitrification system accounts for 1 / 3 of the total investment. However, the current commercial catalyst price is relatively high, which will directly lead to the increase of denitrification technology cost. Therefore, a low cost industrial by-product mixed oxide (M) was selected as the main raw material for the preparation of SCR- ammonia denitrification catalyst. On the basis of the analysis and study of the surface properties of M, the influence of binder on the molding performance of the mixed oxide was investigated, which laid a foundation for the formation of mixed oxide denitrification catalyst. In this paper, the physicochemical properties of mixed oxides were studied by means of XRF,XRD, metallographic microscope. The organic binder (polyvinyl alcohol) was investigated by means of compressive strength, specific surface area of BET and NH_3-TPD. Effects of methyl cellulose and polyacrylamide), inorganic binder (alumina, bentonite) and organic-inorganic binder on the molding properties of mixed oxides. The results show that the specific surface area of the mixed oxide is 1.485 mm2 / g, which is small, which is not conducive to the loading of the active component. The effect of the specific surface area on the activity of the catalyst should be considered in the follow-up study. According to the experimental data, the conditions of mixed oxides used in subsequent experiments were selected: dry milling 45min (1800r/min), sieving more than 80 objects mixed oxides as the main raw material. Through the process of forming mixed oxides with various binders, it can be seen that when organic binders are used to form mixed oxides, the fluidity of slurry is better, and the process of pelletizing, such as pelletizer, pelletizing, etc., is easier to carry out, especially MC. When mixed binder is used to form mixed oxide, the forming characteristics of organic binder also play a leading role. When mixed oxides were molded only with organic binder, the compressive strength of formed oxides was not high, but that of inorganic binder was higher, and the highest compressive strength of bentonite was 1.846 MPA. Compared with using organic binder alone, the addition of inorganic binder can significantly improve the compressive strength. When the mixed oxide is molded with organic binder, the specific surface area of the formed oxide BET is related to the molecular weight of the binder, and the molecular weight is too large. A large amount of gas will form a large number of pores during the roasting process, which will cause the pore structure to collapse. In turn, the specific surface area of the molded material is decreased. The specific surface area of inorganic binder is larger than that of only organic binder, and the specific surface area of oxide BET formed by mixed binder is obviously improved. The comparison of the specific surface area and compressive strength of the best compressive strength obtained by several groups of binders on the mixed oxides shows that, There is no obvious positive correlation between the compressive strength and the specific surface area. The adsorptive properties of the molded oxides formed by binder on mixed oxides are similar to those of ammonia, and the amount of NH_3 adsorbed and the amount of surface acid are not large. There was no significant positive correlation between the adsorption amount and surface acidity of NH_3 and the compressive strength of the formed oxides.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：X701
本文编号：2377102
[Abstract]:At present, SCR method is the most mature technology of flue gas denitrification among many flue gas denitrification methods at home and abroad. However, for this technology, China started late, especially in the preparation of its core technology catalyst has not yet independent intellectual property rights, so in order to more mature use of SCR technology, our country must independently develop SCR denitrification catalyst. As the core of SCR technology, catalyst has broad market demand in China, and its investment in SCR denitrification system accounts for 1 / 3 of the total investment. However, the current commercial catalyst price is relatively high, which will directly lead to the increase of denitrification technology cost. Therefore, a low cost industrial by-product mixed oxide (M) was selected as the main raw material for the preparation of SCR- ammonia denitrification catalyst. On the basis of the analysis and study of the surface properties of M, the influence of binder on the molding performance of the mixed oxide was investigated, which laid a foundation for the formation of mixed oxide denitrification catalyst. In this paper, the physicochemical properties of mixed oxides were studied by means of XRF,XRD, metallographic microscope. The organic binder (polyvinyl alcohol) was investigated by means of compressive strength, specific surface area of BET and NH_3-TPD. Effects of methyl cellulose and polyacrylamide), inorganic binder (alumina, bentonite) and organic-inorganic binder on the molding properties of mixed oxides. The results show that the specific surface area of the mixed oxide is 1.485 mm2 / g, which is small, which is not conducive to the loading of the active component. The effect of the specific surface area on the activity of the catalyst should be considered in the follow-up study. According to the experimental data, the conditions of mixed oxides used in subsequent experiments were selected: dry milling 45min (1800r/min), sieving more than 80 objects mixed oxides as the main raw material. Through the process of forming mixed oxides with various binders, it can be seen that when organic binders are used to form mixed oxides, the fluidity of slurry is better, and the process of pelletizing, such as pelletizer, pelletizing, etc., is easier to carry out, especially MC. When mixed binder is used to form mixed oxide, the forming characteristics of organic binder also play a leading role. When mixed oxides were molded only with organic binder, the compressive strength of formed oxides was not high, but that of inorganic binder was higher, and the highest compressive strength of bentonite was 1.846 MPA. Compared with using organic binder alone, the addition of inorganic binder can significantly improve the compressive strength. When the mixed oxide is molded with organic binder, the specific surface area of the formed oxide BET is related to the molecular weight of the binder, and the molecular weight is too large. A large amount of gas will form a large number of pores during the roasting process, which will cause the pore structure to collapse. In turn, the specific surface area of the molded material is decreased. The specific surface area of inorganic binder is larger than that of only organic binder, and the specific surface area of oxide BET formed by mixed binder is obviously improved. The comparison of the specific surface area and compressive strength of the best compressive strength obtained by several groups of binders on the mixed oxides shows that, There is no obvious positive correlation between the compressive strength and the specific surface area. The adsorptive properties of the molded oxides formed by binder on mixed oxides are similar to those of ammonia, and the amount of NH_3 adsorbed and the amount of surface acid are not large. There was no significant positive correlation between the adsorption amount and surface acidity of NH_3 and the compressive strength of the formed oxides.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：X701
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