常压下固体废弃物热解气的Ni-Fe基催化剂甲烷化反应机理研究
发布时间：2018-11-15 08:53
【摘要】：固体废弃物热解气化是固体废弃物高值化利用的转化方法。将固体废弃物热解气进行甲烷化反应制备合成天然气不仅可以减缓对目前天然气的需求,并且可以提高热解气利用率。固体废弃物热解的不可凝气体产物一般是在常压下输出的,若将输出的气体直接在常压下继续进行甲烷化反应制备合成天然气,便不用再对系统或是合成气加压,这样可以节约运营成本,节省能源。因此,目前需要对常压下甲烷化的工艺条件及甲烷化催化剂需要进行更进一步的研究,以期开发经济高效的常压甲烷化催化剂可以直接与之耦合。本文首先采用γ-Al2O3为载体,用等体积浸渍法,制备了一系列Ni-Fe/Al2O3甲烷化催化剂。实验结果表明,常压下,反应空速在30000 mL/(g·h)-450000 mL/(g·h)范围内,反应温度在230℃C-330℃C范围内进行甲烷化反应最佳。Fe的引入,使得Ni-Fe/y-Al2O3双金属催化剂表现出高的甲烷化活性,CO的转化率接近100%,CH4的选择性可达90%以上。在Ni和Fe的负载量均在15%的情况下,催化剂催化效果达到最佳。BET、XRD及H2-TPR分析表明,Ni-Fe/γ-Al2O3双金属催化剂中Ni、Fe之间产生了明显的相互作用,铁助剂的添加可减少了镍铝尖晶石NiAl2O4的生成,也就增加了游离态的NiO,使催化剂的还原温度降低,NiO的分散度有所提高,提高了催化剂活性。接着进行了15Ni-15Fe/γ-Al2O3催化剂的寿命测试,发现在15Ni-15Fe/y-Al2O3催化剂的寿命12-15 h左右。随后采用沉淀、共沉淀、溶胶凝胶法三种不同的制备方法制备TiO2-Al2O3为复合载体,制备了一系列15Ni-15Fe/TiO2-Al2O3甲烷化催化剂,为了研究Ti02的添加与制备方法对催化剂甲烷化活性与寿命的影响。实验结果表明,添加Ti02之后可以使15Ni-15Fe/y-Al2O3催化剂具有更宽的甲烷化适宜温度范围。溶胶凝胶法制备的15Ni-15Fe/TiO2-Al2O3催化剂的甲烷化活性最高。Ti02的添加增加了15Ni-15Fe/y-Al2O3催化剂的抗积碳的能力。BET、XRD、TEM及H2-TPR分析表明,载体中加入部分Ti02可削弱γ-Al2O3与NiO的相互作用,也就是减少了镍铝尖晶石NiAl2O4的生成,可使NiO晶粒细化,增加NiO晶粒在载体γ-Al2O3表面上的分散。溶胶凝胶法制备的15Ni-15Fe/TiO2-Al2O3催化剂的活性组分NiO的分散程度最高,达到纳米级,催化活性最好,并且稳定性好,有最强的抗积碳能力。接着进行了三种15Ni-15Fe/TiO2-Al2O3催化剂的寿命测试,溶胶凝胶法制备的15Ni-15Fe/TiO2-Al2O3催化剂的寿命最长。最后本文采用Powell(PO)优化方法,建立了催化剂甲烷化宏观动力学模型,利用Aspen Plus软件进行了甲烷化流程模拟,通过甲烷化的过程模拟对催化剂的甲烷化宏观动力学模型进行了进一步的验证,15Ni-15Fe/TiO2-Al2O3催化剂对CH4的选择性更高,并且15Ni-15Fe/TiO2-Al2O3催化剂的甲烷化反应更加迅速。
[Abstract]:Pyrolysis and gasification of solid waste is a conversion method for high value utilization of solid waste. The methanation reaction of solid waste pyrolysis gas to synthetic natural gas can not only slow down the demand for natural gas but also improve the utilization ratio of pyrolysis gas. The non-condensable gas products of solid waste pyrolysis are generally exported under atmospheric pressure. If the exported gas continues to methanize directly under normal pressure to produce synthetic natural gas, there is no need to pressurize the system or syngas. This can save operating costs, save energy. Therefore, it is necessary to further study the process conditions of methanation under atmospheric pressure and the methanation catalyst in order to develop an economical and efficient atmospheric methanation catalyst that can be directly coupled with it. In this paper, a series of Ni-Fe/Al2O3 methanation catalysts were prepared by using 纬-Al2O3 as carrier and isobaric impregnation method. The experimental results show that under atmospheric pressure, the reaction space velocity ranges from 30000 mL/ (g h) to 450000 mL/ (g h), and the reaction temperature is in the range of 230 鈩，
本文编号：2332820
[Abstract]:Pyrolysis and gasification of solid waste is a conversion method for high value utilization of solid waste. The methanation reaction of solid waste pyrolysis gas to synthetic natural gas can not only slow down the demand for natural gas but also improve the utilization ratio of pyrolysis gas. The non-condensable gas products of solid waste pyrolysis are generally exported under atmospheric pressure. If the exported gas continues to methanize directly under normal pressure to produce synthetic natural gas, there is no need to pressurize the system or syngas. This can save operating costs, save energy. Therefore, it is necessary to further study the process conditions of methanation under atmospheric pressure and the methanation catalyst in order to develop an economical and efficient atmospheric methanation catalyst that can be directly coupled with it. In this paper, a series of Ni-Fe/Al2O3 methanation catalysts were prepared by using 纬-Al2O3 as carrier and isobaric impregnation method. The experimental results show that under atmospheric pressure, the reaction space velocity ranges from 30000 mL/ (g h) to 450000 mL/ (g h), and the reaction temperature is in the range of 230 鈩，
本文编号：2332820
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