加压流化床Co-Ca催化煤焦加氢气化反应动力学  

Kinetics of Co-Ca catalyzed coal char hydrogasification in a pressurized fluidized bed

作　　者：刘佳敏 顾素敏 张荣[2] 李伟伟[1] 曲旋[2] LIU Jiamin;GU Sumin;ZHANG Rong;LI Weiwei;QU Xuan(School of Chemistry and Chemical Engineering,North University of China,Taiyuan 030051,China;State Key Laboratory of Coal Conversion,Institute of Coal Chemistry,Chinese Academy of Sciences,Taiyuan 030001,China)

机构地区：[1]中北大学化学与化工学院,山西太原030051 [2]中国科学院山西煤炭化学研究所煤炭高效低碳利用全国重点实验室,山西太原030001

出　　处：《洁净煤技术》2024年第5期128-135,共8页Clean Coal Technology

基　　金：山西省重点研发计划资助项目(202102090301029);山西省基础研发计划青年资助项目(202303021212379,20210302124357);省部共建煤基能源清洁高效利用国家重点实验室开放课题资助项目(SKL202103)。

摘　　要：煤催化加氢气化是极具发展潜力的煤制天然气技术,包括煤催化加氢热解和煤焦催化加氢气化2个步骤,其中煤焦催化加氢气化的反应速率远小于煤催化加氢热解的反应速率,是整个气化过程的速率控制步骤,因此建立适宜的煤焦催化加氢气化反应动力学对该技术的应用具有重要的意义。在小型加压流化床中,研究了Co-Ca催化煤焦加氢气化过程中煤焦颗粒密度和孔隙结构随碳转化率的变化规律,发现随反应进行煤焦颗粒密度减小,孔隙总比表面积与反应速率线性相关,表明Co-Ca催化煤焦加氢气化反应符合随机孔模型的特征。通过调控反应温度、氢分压和Co负载量,获得了煤焦中碳转化率的变化规律。结果表明:650~850℃反应仍处于动力学控制阶段;反应温度超过750℃后,反应速率显著提升,进一步提升温度至850℃时,碳转化率由650℃时的16.32%增至95.32%。随氢分压升高,碳转化率增大,氢气分压由0.6 MPa增至2.5 MPa时,碳转化率由19.49%提高至94.11%。随Co催化剂负载量由1%提高至3%,碳转化率持续提升,继续增加Co负载量至5%,碳转化率变化较小。采用扩展随机孔模型,引入经验参数c和p对试验数据进行分析,得到煤焦催化加氢气化反应的活化能为122.7 kJ/mol,反应级数为1.54。模型预测的反应速率值与试验值之间的平均偏差为4.81%。The coal catalytic hydrogasification is a highly promising technology for converting coal to natural gas.It consists of coal catalytic hydropyrolysis and char catalytic hydrogasification.The char catalytic hydrogasification is the rate-controlling step of the whole process because its rate is much less than that of coal catalytic hydropyrolysis.Therefore,it is critical to establish a reasonable kinetic model of Co-Ca catalyzed char hydrogasification in pressurized fluidized bed for the technology′s future development.The variations of particle density and pore characteristics with carbon conversion were investigated during Co-Ca catalyzed char hydrogasification in a lab-scale pressurized fluidized bed.The results show that the char particle density decrease as the carbon conversion,and there is linear correlation between the total pores specific surface area and reaction rate.These phenomena confirm that the conversion of char should follow the random pore model during Co-Ca catalyzed char hydrogasification.The effects of reaction temperature,hydrogen pressure,and Co loading on the carbon conversion were researched.It is found that the reaction is controlled by dynamics in the range of 650-850℃.The reaction rate is dramatically increased when the temperature is over 750℃,and the carbon conversion increase from 16.32%to 95.32%when reaction temperature is elevated from 650℃to 850℃.The carbon conversion is elevated to 94.11%with increasing the hydrogen partial pressure from 0.6 MPa to 2.5 MPa.Raising the Co loading from 1%to 3%resultes in the continous increase in carbon conversion,but it has little change when the Co loading is furtherly increased to 5%.The experiment data was analyzed adopting an extended random pore model with the introduction of empirical parameters c and p.The results indicate that the activation energy of coal char catalytic hydrogasification is 122.7 kJ/mol,and the reaction order is 1.54.The average deviation between the predicted and experimental reaction rate is 4.81%.

关 键 词：煤焦 催化加氢气化 加压流化床 反应动力学 随机孔模型 

分 类 号：TQ53[化学工程—煤化学工程]