一步法煤制天然气催化剂设计及工艺研究

发布时间：2018-01-04 19:38

  本文关键词：一步法煤制天然气催化剂设计及工艺研究　出处：《青岛科技大学》2015年硕士论文　论文类型：学位论文

  更多相关文章： 煤 天然气 催化剂 反应动力学 回收

【摘要】：能源是社会经济发展的基础,鉴于我国富煤贫气的基本国情,大力发展清洁煤技术是实现我国能源安全的重要保证。一步法煤制天然气技术是指在催化剂的作用下,煤粉颗粒与通入的水蒸气发生反应,实现在一个反应器中同时发生煤气化和甲烷化反应生成天然气的技术。在该技术中甲烷化反应释放的热量可为煤气化反应提供部分所需热量,从而降低能耗。与传统的煤气化转化技术(两步法)相比,一步法煤制天然气技术设备少,投资小,能耗低,因此成为新的研究热点。本文利用固定床反应器对制备的一步法煤制天然气催化剂进行了研究,详细的考察了工艺参数对反应的影响,并建立了动力学模型,最后对催化剂的回收和工艺改进做了初步探究,具体工作如下：1、采用浸渍法制备了K-Ni复合催化剂,在固定床反应器中,考察了不同活性组分含量的催化剂的催化性能以及煤种对催化剂性能的影响。实验结果表明K-Ni复合催化剂中活性组分K和Ni具有协同效应,可生成具有高活性的K2Ni02和K3M2O4使反应速率加快；当K：Ni=2：1时,其催化效果是单组份K2SO4的2-3倍；引入CaO可有效吸收反应生成的CO2,促进反应向生成CH4的方向进行；在K:Ni:C=2:1:1.5时,甲烷含量较未加CaO均提高40%左右。2、考察了温度、压力、催化剂负载量和初始水碳比等工艺参数对反应的影响,并确定了最佳工艺条件。结果表明：升高温度可使碳转化率明显增加,低于700℃时,甲烷化反应未达到平衡,气体生成受动力学控制,适宜的反应温度为600-700℃：升高压力对CH4产率促进明显,合适的反应压力为2.0 MPa；碳转化率随着H2O流量增加而增加,在初始水碳比达到1：1时,颗粒表面水蒸气接近饱和,继续增大水碳比,碳转率增加缓慢,而CH4产率呈先增大后减小的趋势,在水碳比为1.0附近存在最大值。添加催化剂可明显提高CH4产量,K-Ni二元复合催化剂的负载饱和度为10%。3、采用三种动力学模型(均相反应模型,缩核模型及修正随机孔模型)对煤-水蒸气催化气化动力学曲线进行拟合,拟合结果表明,修正随机孔模型效果最好。采用K-Ni-Ca三元复合催化剂可使神木煤焦颗粒的活化能下降101.88kJ·mol-1,使气化反应在更温和的条件下快速进行。4、对催化剂的回收进行了初步研究,采用逐级水洗和水渣分离的方法将尽可能多的催化剂富集到溶液当中,然后再负载在新鲜待反应的煤焦上,进行催化气化“一步法”煤制天然气研究。研究表明当洗涤时间4h,水渣比20：1,洗涤次数为4次,搅拌速率400 r·min-1,催化剂可回收80%左右。最后对煤-水蒸气催化气化生产天然气工艺进行了初步改进。
[Abstract]:Energy is the basis of social and economic development, in view of the basic national conditions of rich coal and poor gas. The development of clean coal technology is an important guarantee to realize energy security in China. One-step coal technology for natural gas production refers to the reaction between pulverized coal particles and the water vapor flowing in under the action of catalyst. The technology of producing natural gas from coal gasification and methanation simultaneously in a reactor, in which the heat released from the methanation reaction provides part of the heat required for the coal gasification reaction. Compared with traditional coal gasification conversion technology (two-step method), one-step coal production technology has less equipment, less investment and lower energy consumption. Therefore, it has become a new research hotspot. In this paper, a fixed-bed reactor was used to study the preparation of one-step coal to natural gas catalyst, the effects of process parameters on the reaction were investigated in detail, and a kinetic model was established. Finally, the recovery and process improvement of the catalyst were studied. The specific work was as follows: 1. K-Ni composite catalyst was prepared by impregnation method, and the catalyst was prepared in a fixed-bed reactor. The catalytic performance of the catalyst with different active components and the effect of coal on the catalyst performance were investigated. The results showed that the active components K and Ni in the K-Ni composite catalyst had synergistic effect. K2Ni02 and K3M2O4 with high activity can accelerate the reaction rate. The catalytic effect of K: Ni2: 1 is 2-3 times as much as that of one-component K2SO4. The introduction of CaO can effectively absorb the CO _ 2 produced by the reaction and promote the reaction to the direction of the formation of CH4. At K: Ni: 2: 1: 1.5, the methane content increased by 40% or so compared with that without CaO. The temperature and pressure were investigated. The effects of catalyst loading amount and initial water-carbon ratio on the reaction were investigated, and the optimum process conditions were determined. The results showed that the carbon conversion increased obviously when the temperature was raised, and the reaction temperature was lower than 700 鈩，

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