基于热烧结矿多组分耦合自适应催化脱硝研究

Coal is a necessary raw material of the sintering process, and NOx from coal combustion is one of the imporatant pollutants in iron and steel industry. At present, selective catalytic reduction(SCR) techonolgy for sintering flue gas has the shortcomings such as high investment and operation cost, catalyst deactivation. In this project, the adaptive selective catalytic reduction of NO by NH3 combined with the multi-metal oxides in the hot sintered ore is proposed according to the characteristic of the sintering process. At first, the adsorption-reaction characteristic of NO, NH3 and O2 on the surface of the sintered ore will be experimentally investigated, and the interreaction between multi-pollutant and their intermedia products during SCR are also charactered, then the chemcial reaction paths and their kinetic parameters are obtained. Thus, the mechanism of de-NOx by NH3 combined with the multi-metal oxides in the hot sintered ore is discovered. At last, the influence of operation parameters(reaction temprature, space velocity, NH3/NO ratio and moisture on denitrification efficiency is also discussed.

烧结混合料中煤燃烧产生的NOx是钢铁行业主要污染物之一。针对烧结烟气SCR技术投资和运行成本高、催化剂易中毒失活等问题，结合烧结工艺，本项目提出利用热烧结矿显热加热湿法脱硫后烧结烟气，实现烧结矿自适应催化脱硝的新方法。通过研究NO、NH3及O2在烧结矿表面的吸附-反应特性，分析多污染物及中间产物之间相互竞争、协同机制，获得其相应的反应动力学参数和反应途径，从而揭示热烧结矿选择性催化还原NO的机理；掌握反应温度、空速比、NH3/NO和水分等参数对热烧结矿自适应选择性催化还原脱硝效率的影响规律。本项目的研究为实现热烧结矿自适应选择性催化还原脱硝技术的推广应用奠定理论基础。

针对烧结烟气SCR技术投资和运行成本高、催化剂容易中毒失活等问题，本项目提出利用热烧结矿显热加热烧结烟气，实现烧结矿自适应催化脱硝的新方法。具体研究结果如下：.（1）分析烧结矿催化脱硝过程多污染物及中间产物之间相互竞争、协同作用机制，揭示烧结矿多组分耦合自适应催化脱硝的机理。通过对烧结矿催化剂进行XRF、XRD、BET、SEM、H2-TPR、XPS和In-situ FTIR等表征发现，烧结矿催化剂中起活性作用的主要为铁的氧化物，且主要以Fe3+的形式存在。烧结矿催化脱硝反应同时遵循Eley-Rideal机理和Langmuir-Hinshelwood机理。.（2）获得烧结矿多组分耦合自适应催化脱硝的化学反应动力学参数。烧结矿和酸改性烧结矿催化还原NOx的活化能分别为83.66 和59.93 kJ/mol，指前因子A分别为143.51和114.54 s-1。酸改性烧结矿催化脱硝反应的活化能低于烧结矿催化脱硝反应的活化能。因为酸改性增强了催化剂本身对于NO和NH3的吸附作用，使得同一时间催化剂表面有更多吸附态反应组分，同时优化了E-R和L-H反应路径，促进了反应进行，从而提高NOx转化率。.（3）获得工艺参数对烧结矿多组分耦合自适应催化脱硝效率影响。研究发现：烧结矿催化剂NOX转化窗口温度约为250~350℃。水分能促进烧结烟气中的NOX转化，SO2对烧结矿NOX转化的抑制作用小于水分和SO2共存时的情况。在烧结矿粒径为0.15~0.25mm，反应温度为300℃，空速为1000h-1，NH3/NO比为1.0时，烧结矿对模拟烧结烟气的NOX转化率可达60%以上。采用酸改性烧结矿可以提供更多的酸位点，提高脱硝性能；在温度为300 ℃，空速比为5000 h-1，NH3/NO=1的反应条件下，其酸改性烧结矿对NOx转化率稳定在92 %左右。.（4）开发热烧结矿多组分耦合自适应催化脱硝技术。结合烧结矿特性和现有烧结工艺，本项目开发了基于SDA脱硫的烧结烟气NOX治理工艺和基于氨法脱硫的烧结烟气NOX治理工艺。