褐煤制天然气复合催化剂的研究

发布时间：2018-03-11 10:40

本文选题：褐煤　切入点：天然气　出处：《青岛科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着经济的迅速发展和能源需求的不断增加,我国的煤炭资源消耗巨大,烟煤、无烟煤等高阶煤炭资源储量日益减少。因此,褐煤、气煤等低阶煤的利用越来越受到人们的重视。天然气作为一种低碳环保、高效清洁的绿色能源,目前在很多领域得到了广泛的应用,而“富煤、贫油、少气”的能源结构导致我国天然气供需矛盾日益突出,因此通过煤制天然气技术将低阶煤炭资源转化为高效清洁的天然气资源是符合我国能源可持续发展的一条重要道路。通过煤制天然气不仅可以使得煤炭资源得到深度利用,提高能源利用效率,还能缓解我国天然气短缺造成的供需矛盾,对保障我国的能源安全具有非常重大的意义。本文采用“一步法”褐煤直接制天然气,是将褐煤颗粒、催化剂混合后放入固定床反应器中,并在高温下通入水蒸气,该反应器内同时发生煤气化和合成气甲烷化反应,煤气化反应所需要的部分热量可由甲烷化反应提供,从而降低了反应的能耗。该技术与煤气化制得合成气再由合成气转化为甲烷的间接甲烷化技术相比具有投资少,能耗低等优点。本文主要针对褐煤“一步法”制天然气催化剂的制备及性能进行了研究,主要内容如下。首先,以γ-Al2O3为载体,通过浸渍法分别制备了以氢氧化钾、硝酸镍及钼酸铵为前驱体的单组分褐煤直接甲烷化催化剂。并在650℃,2 MPa的条件下采用“一步法”于固定床反应器中对上述单组分催化剂的催化气化及甲烷化性能进行了考察。实验结果表明,在K30催化剂与褐煤煤焦表面的相互作用能有效促进褐煤的气化,北宿褐煤的碳转化率提高较大,合成气及甲烷含量较高,说明其具有较好的催化气化及甲烷化效果。Ni15催化剂能有效提高褐煤碳转化率及甲烷产量,而少量Mo基催化剂对褐煤的催化具有一定的促进作用,但负载量过多会造成载体孔道的堵塞并在载体表面发生团聚现象,从而阻碍了催化反应的正向进行,降低了催化剂的活性。其次,以γ-Al2O3为载体,通过浸渍法制备了双组分催化剂Ni-Mo催化剂、Ni-Ca催化剂和Ni-K催化剂。并考察了双组分催化剂对褐煤催化气化及甲烷化性能的影响。Ni-Mo双组分催化剂催化效果不佳,甚至低于单组分的Ni基催化剂,说明Ni-Mo双组分催化剂对于褐煤的催化作用较弱。Ni-Ca双组分催化剂有利于褐煤的催化气化及甲烷化,少量Ca对于褐煤的碳转化率、合成气含量及甲烷产量都有了大量的提高,特别是Ni15Ca10催化剂的催化效果较好。当Ca负载量增多时,催化效果有所下降。而Ni-K双组分催化剂相较于Ni-Mo催化剂和Ni-Ca催化剂的催化作用明显提高,且随着K负载量的不断增加,其催化效果明显加强。当K负载量为30%时,即Ni15K30催化剂的催化效果最佳,褐煤的碳转化率、合成气含量和甲烷含量都有了大幅度的提升。当温度为650-C、2 MPa、水碳比为1：1时,褐煤的碳转化率及甲烷产量能达到最佳。本实验采用修正随机孔模型、均相反应模型和收缩核模型对三种双组分催化剂催化褐煤甲烷化反应过程进行了拟合。结果表明,修正随机孔模型的对其拟合度最高,说明修正随机孔模型能很好地揭示三种催化剂对褐煤催化甲烷化的行为,并证明该反应的控制步骤为界面反应控制。
[Abstract]:Along with the rapid economic development and increasing energy demand, China's coal resources consumption is huge, bituminous coal, anthracite coal resources reserves of high order is reduced. Therefore, the use of lignite, gas coal and other low rank coal has been paid more attention. The natural gas as a low carbon environmental protection, efficient and clean green energy at present, in many fields has been widely used, and rich in coal, oil, energy structure less gas "leads to the contradiction of China's natural gas supply and demand have become increasingly prominent, so the coal gas technology will low rank coal resources into natural gas resources and efficient cleaning is consistent with an important road of sustainable energy development country. By coal and natural gas can not only make the depth of the use of coal resources, improve energy efficiency, but also alleviate the contradiction between supply and demand of China's natural gas shortage caused, to protect China's energy security It has a very important significance. This paper uses the "direct preparation of natural gas by lignite, the lignite particles mixed into the catalyst in fixed bed reactor, and the water vapor at high temperature, simultaneous coal gasification and syngas methanation reaction in the reactor part to heat the coal gasification reaction can be provided by the methanation reaction, thereby reducing the energy consumption of the reaction. The technology of coal gasification process and synthesis gas is converted from syngas for indirect methanation technology of methane compared with less investment, lower energy consumption. In this paper, the lignite" one-step "natural gas catalyst preparation and properties of study, the main contents are as follows. First, the gamma -Al2O3 as carrier, was prepared by the impregnation method were prepared by using potassium hydroxide, ammonium molybdate and nickel nitrate as single component lignite precursors direct methanation catalyst. And at 650 DEG C, 2 MP Under the condition of a by using the "one-step" in a fixed bed reactor for the single component catalyst for catalytic gasification and methanation were investigated. The experimental results show that can effectively promote the gasification of lignite in the interaction between K30 catalyst and lignite char surface, the carbon conversion rate of lignite coal is larger, higher synthesis gas and methane content, the catalytic gasification and methanation catalyst.Ni15 good effect can effectively improve the lignite conversion rate of carbon and methane production, and a small amount of Mo based catalyst for catalytic lignite has a certain role, but the load will cause excessive pore blockage and agglomeration of the carrier surface, thereby hinder the positive catalytic reaction, the activity of the catalyst was reduced. Secondly, using gamma -Al2O3 as carrier, prepared by the impregnation method of two-component catalyst and Ni-Mo catalyst, Ni-Ca catalyst Ni-K catalyst was investigated. And the effect of two-component catalyst on the catalytic gasification of lignite and methanation properties of.Ni-Mo bicomponent catalyst effect is poor, even lower than the single component Ni based catalyst, Ni-Mo double component catalyst for the catalytic effect of lignite is weak.Ni-Ca bicomponent catalyst for the catalytic gasification of lignite methane, a small amount of Ca for lignite carbon conversion, the content of synthesis gas and methane production has a lot of improvement, especially good catalytic effect of Ni15Ca10 catalyst. When Ca loading increased, the catalytic effect decreases. And the catalytic effect of Ni-K two-component catalyst compared with Ni-Mo catalyst and Ni-Ca catalyst was improved and, with the increase of K loading, the catalytic effect is obviously enhanced. When the K loading was 30%, the catalytic effect of Ni15K30 catalyst, lignite carbon conversion, synthesis gas The amount and content of methane have been improved greatly. When the temperature is 650-C, 2 MPa, ratio of water to carbon is 1:1, lignite carbon conversion rate and yield of methane can reach the best. This experiment adopts the modified random pore model, homogeneous reaction model and the shrinking core model of three kinds of two-component catalyst of lignite the methanation reaction process was simulated. The results show that the modified random pore model to fit the highest, indicating the modified random pore model can well reveal three kinds of catalysts on the catalytic methanation of lignite, and prove that the control step of the reaction to interface reaction control.

【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ426;TE665.3

【参考文献】