载镍活性炭低温脱硫及其制备影响因素研究

Influence Factors and Preparation Conditions of Ni/AC Used as A Low-temperature Desulfurizer

活性炭负载镍催化剂具有较好的低温脱硫性能。为研发适合钢铁企业烧结烟气低温脱硫的活性炭,以椰壳活性炭为研究对象,采用硝酸镍浸渍法制备载镍活性炭,使用模拟烧结烟气开展了炭基和载镍(0.5%、1%、2%、3%、4%)活性炭(0.5Ni/AC、1Ni/AC、2Ni/AC、3Ni/AC、4Ni/AC)脱硫实验,并通过扫描电镜和X射线衍射仪对炭基和催化剂进行表征。炭基脱硫性能研究结果表明,当反应温度为30℃时,炭基活性炭脱硫效果最好,反应温度越低对物理吸附越有利,反应温度越高对化学吸附越有利;分析表明炭基脱硫机理为SO_2、O_2和H_2O被活性炭吸附成为吸附态,主要在微孔条件下形成硫酸。载镍活性炭脱硫反应温度、空速和SO_2入口质量分数影响因素研究结果表明,反应温度为60℃时,1Ni/AC催化剂具有最佳的脱硫率,其保持100%脱硫率的时间长达120 min;脱硫剂的脱硫率随空速的升高而不断下降,低空速有利于反应的进行;SO_2的入口质量分数在0.1%~0.3%时,有利于脱硫反应的进行。分析脱硫前后催化剂表征结果可知,脱硫反应后会在活性炭孔表面出现大量脱硫产物,堵塞了活性炭孔道,覆盖了催化剂表面的活性位,中断了催化剂脱硫反应链。当焙烧温度大于900℃时,镍全部以单质镍形式存在于活性炭中;600~800℃焙烧温度条件下,脱硫剂具有较高的脱硫率,镍的主要存在形态为Ni O。当Ni的负载量为1%时,脱硫剂具有最好的脱硫效果。研究结果可为烧结烟气低温脱硫及多污染物协同治理提供借鉴。

Activated carbon （AC）-loaded nickel （Ni） exhibits good low-temperature desulfurization performance. In this study, coconut husk AC was the object under investigation, with the aim of developing AC for the low-temperature desulfurization of iron-steel sintering flue gas. Ni/AC was prepared using the nickel nitrate immersion method. By simulating sintering flue gas, the desulfurization performances of AC and Ni/AC （0.5%, 1%, 2%, 3% and 4%, marking as 0.5Ni/AC, 1Ni/AC, 2Ni/AC, 3Ni/AC and 4Ni/AC, respectively） were analyzed by conducting a desulfurization experiment. The surface properties of AC and Ni/AC were observed by SEM and X-rays. The AC desulfurization test results were as follows： the reaction temperature at 30°C exhibited good desulfurization performance, the low reaction temperature was propitious to physical adsorption, the high reaction temperature was propitious to chemical adsorption, and the desulphurization mechanism involved AC absorbing SO2, O2, and H2O, then, adsorbates turned into sulfuric acid under millipore conditions. The desulfurizer influence factors of reaction temperature, airspeed, and SO2 mass fractions of entrance were investigated by conducting a 1Ni/AC desulfurization experiment. The characterization results revealed the following： the reaction temperature at 60 ℃ exhibited good desulfurization performance, the endurance time of 100% desulfurization ratio could be maintained for 120 min, the low airspeed was propitious to desulfurization, and the SO2 mass fractions of entrance between 0.1% and 0.3% was propitious to desulfurization. By analyzing the characterization results, we observed that there were many desulfurization products that existed on the pore surface. The desulfurization products jammed the pore path and covered the active site. Finally, the reaction chain of desulfurization was cut off. When the sintering temperature was higher than 900 ℃, the nickel was a simple substance . When the sintering temperature was between 600 ℃ and 800 ℃, the catalyst had a high desulfurization ratio, and the nickel turned into NiO. Then, the Ni load quantity equaled 1% and the AC exhibited better low-temperature desulfurization performance. These research findings can aid in low-temperature desulfurization and the simultaneous control of multiple pollutants for iron-steel sintering flue gas.