基于镍基催化剂的合成气甲烷化研究
发布时间：2019-06-06 20:20
【摘要】：随着经济的快速发展,我国对天然气的需求逐年增加,而中国的能源结构特点是:"富煤、贫油、少气"。我国的天然气供不应求,需要大量进口,费用昂贵。但我国是煤炭大国,并含有丰富的可再生资源—生物质。因此,利用相对丰富的煤或生物质资源制取天然气是缓解我国天然气能源紧张的有效途径之一。合成气合成甲烷是天然气合成工艺的一个关搖技术。本文对合成气合成甲烷进行了系统研究。首先是CO甲烷化的研究,分别用沉积沉淀法和共沉淀法制备了催化剂Ni/Ti02,研究制备方法对催化剂甲烷化催化性能的影响。发现采用共沉淀法制备的催化剂Ni/Ti02的整体催化性能要明显优于沉积沉淀法所制备的催化剂,这主要是因为共沉淀法制备的催化剂具有更大的比表面积和更多的活性位数量,且活性组分Ni在载体上高分散度。然后采用上文所述的共沉淀法制备了催化剂:Ni/Al_2O_3、Ni/Zr02、Ni/Ce02,发现三种催化剂在低温下的活性排序为:Ni/Al_2O_3Ni/Zr02Ni/Ce02,催化剂Ni/Al_2O_3表现了最佳的催化活性和良好稳定性。在P=1MPa,GHSV=20000ml/g.h,H_2/CO=3,T=380℃的反应条件下,催化剂Ni/Al_2O_3的CO转化率和CH4选择性分别达到了 100%和94.5%。表征结果显示活性组分Ni的分散度是影响不同载体Ni基催化剂甲烷化催化活性的主要因素,Ni的分散度越高,催化剂的催化活性越好。接着挑选CO甲烷化研究中催化性能最好的催化剂Ni/Al_2O_3进行H_2S对甲烷化的影响研究。在 P=1MPa,GHSV=20000ml/g.h,H_2/CO=3,T=440℃,不同 H_2S含量(0,100ppm和200ppm)的反应条件下,对比催化剂的稳定性,研究发现H_2S的存在会大大降低催化剂的稳定性,且H_2S的浓度越高,催化剂的稳定性越差。当H_2S的浓度为200ppm时,催化剂Ni/Al_2O_3失活很快,仅反应了 5小时就完全失活。最后将分子筛MCM-41引入催化剂载体进行C02甲烷化的研究,采用沉积沉淀法制备催化剂Ni/MCM-41,发现催化剂Ni/MCM-41具有较好的CO_2催化效果,反应温度为260-460℃的条件下,催化剂的CO_2转化率和CH4选择性都随着TTT温度的增加而增大,但随着空速的增加而降低。压力的增加可以大幅度提高催化剂Ni/MCM-41的催化性能,CO转化率和CH4选择性的最大值分别从常压的73.3%、98.5%增大到1.5MPa压力的91.2%、99.6%。同时发现助剂Ce02的添加也能改善催化剂Ni/MCM-41的催化活性,催化剂整体性能随着助剂Ce02添加量的增加而不断提高,且催化剂Ni/20%CeO_2-MCM-41表现出了最佳的催化剂活性,常压下,C02转化率和CH4选择性分别达到85.6%和99.8%。但随Ce02的继续增加,催化活性反而降低。
[Abstract]:With the rapid development of economy, China's demand for natural gas is increasing year by year, and China's energy structure is characterized by: the "rich coal, lean oil and less gas". The supply of natural gas in our country is in short supply, which requires a large amount of import and is expensive. But China is a big coal country and contains rich renewable resources and biomass. Therefore, using relatively rich coal or biomass resource to make natural gas is one of the effective ways to relieve the energy of natural gas in China. Synthesis of methane from synthesis gas is an important technology for natural gas synthesis. This paper systematically studies the synthesis of methane from synthesis gas. The catalyst Ni/ Ti02 was prepared by the deposition and precipitation method, and the effect of the preparation method on the catalytic performance of the catalyst was studied. It is found that the overall catalytic performance of the catalyst Ni/ Ti02 prepared by the co-precipitation method is better than that of the catalyst prepared by the deposition precipitation method, which is mainly because the catalyst prepared by the coprecipitation method has a larger specific surface area and a larger number of active sites, and the active component Ni has a high degree of dispersion on the support. The catalyst: Ni/ Al _ 2O _ 3, Ni/ Zr02, Ni/ Ce02 was prepared by the co-precipitation method as described above. The activity of three catalysts at low temperature was found to be: Ni/ Al _ 2O _ 3Ni/ Zr02Ni/ Ce02, and the catalyst Ni/ Al _ 2O _ 3 exhibited the best catalytic activity and good stability. The CO conversion and CH4 selectivity of the catalyst Ni/ Al _ 2O _ 3 reached 100% and 94.5% respectively under the reaction conditions of P = 1 MPa, GHSV = 20000 ml/ g. h, H _ 2/ CO = 3, T = 380 鈩，
本文编号：2494570
[Abstract]:With the rapid development of economy, China's demand for natural gas is increasing year by year, and China's energy structure is characterized by: the "rich coal, lean oil and less gas". The supply of natural gas in our country is in short supply, which requires a large amount of import and is expensive. But China is a big coal country and contains rich renewable resources and biomass. Therefore, using relatively rich coal or biomass resource to make natural gas is one of the effective ways to relieve the energy of natural gas in China. Synthesis of methane from synthesis gas is an important technology for natural gas synthesis. This paper systematically studies the synthesis of methane from synthesis gas. The catalyst Ni/ Ti02 was prepared by the deposition and precipitation method, and the effect of the preparation method on the catalytic performance of the catalyst was studied. It is found that the overall catalytic performance of the catalyst Ni/ Ti02 prepared by the co-precipitation method is better than that of the catalyst prepared by the deposition precipitation method, which is mainly because the catalyst prepared by the coprecipitation method has a larger specific surface area and a larger number of active sites, and the active component Ni has a high degree of dispersion on the support. The catalyst: Ni/ Al _ 2O _ 3, Ni/ Zr02, Ni/ Ce02 was prepared by the co-precipitation method as described above. The activity of three catalysts at low temperature was found to be: Ni/ Al _ 2O _ 3Ni/ Zr02Ni/ Ce02, and the catalyst Ni/ Al _ 2O _ 3 exhibited the best catalytic activity and good stability. The CO conversion and CH4 selectivity of the catalyst Ni/ Al _ 2O _ 3 reached 100% and 94.5% respectively under the reaction conditions of P = 1 MPa, GHSV = 20000 ml/ g. h, H _ 2/ CO = 3, T = 380 鈩，
本文编号：2494570
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