费托合成蛋壳型催化剂活性组分厚度的模拟计算

doi:10.11949/0438-1157.20190241

摘要/Abstract

摘要：

采用Comsol-Multiphysics软件对蛋壳型Co基催化剂费托合成反应体系进行了CFD模拟计算。通过建立合理的费托合成催化剂颗粒三维模型进行计算，重点研究了催化剂活性组分厚度对费托合成反应产物分布、温度分布以及转化率的影响。结果表明：费托合成反应内扩散阻力较大，CO在催化剂表面和内部存在明显的浓度差。且由于H₂的扩散速率远大于CO的扩散速率，导致催化剂颗粒内部氢碳比很高，不利于油类和蜡类物质的生成；随着催化剂活性组分厚度的增加，CO转化率逐渐提高，甲烷和低碳烃的选择性逐渐增大，而C₁₀H₂₂和C₂₂H₄₆的选择性逐渐减小；催化剂颗粒内部的温度峰值逐渐向催化剂内部移动，不利于反应热的转移。对于尺寸为?2.5 mm的蛋壳型球形催化剂，较佳的催化剂活性组分厚度为0.125 mm。

关键词: 费托合成, 计算流体力学, 扩散, 催化剂, 活性组分厚度

Abstract:

The CFD simulation of the egg-shell Co-based catalyst Fischer-Tropsch synthesis reaction system was carried out by Comsol-Multiphysics software. The effects of catalyst active component thickness on product and temperature distribution, conversion of F-T synthesis were studied by establishing a reasonable three-dimensional model of catalyst. The results show that the CO concentration has obvious difference between the outside and inside of catalyst due to strong diffusion limitation. And because the diffusion rate of H₂ is much larger than the diffusion rate of CO, the internal hydrogen-carbon ratio of the catalyst particles is very high, which is not conducive to the formation of oils and waxes. As the thickness of catalyst active components increases, the conversion of CO and the selectivity of methane and low hydrocarbons increases, while the selectivity of C₁₀H₂₂ and C₂₂H₄₆ decreases. The peak temperature inside the catalyst moves towards the inside of the catalyst, which isn’t conducive to the transfer of reaction heat. For the shell-type spherical catalyst with the size of 2.5mm, the optimum catalyst thickness of the active component is 0.125 mm.

Key words: F-T synthesis, computational fluid dynamics, diffusion, catalyst, thickness of active components

中图分类号:

TQ 021.4

应景涛, 李涛. 费托合成蛋壳型催化剂活性组分厚度的模拟计算[J]. 化工学报, 2019, 70(9): 3404-3411.

Jingtao YING, Tao LI. Simulation of active component thickness of egg-shell catalyst for F-T synthesis[J]. CIESC Journal, 2019, 70(9): 3404-3411.

图/表 9

图1 蛋壳型球形催化剂

Fig.1 Schematic chart of egg-shell spherical catalyst

图2 球状催化剂的网格划分

Fig.2 Grid structure division

表1 动力学参数

Table 1 Kinetic parameters

参数	k ₀	E/(kJ/mol)
k=k ₀₁exp(-E ₁ /RT)	$1.0628 × 107 m o l / g ? h ? M P a 2$	76.01
a=k ₀₂exp(-E ₂ /RT)	0.3899 MPa^-1/2	1.789
b=k ₀₃exp(-E ₃ /RT)	0.9853 MPa^-1	16.13
c=k ₀₄exp(-E ₄ /RT)	0.1715 MPa^-3/2	1.240

表1 动力学参数

Table 1 Kinetic parameters

参数	k ₀	E/(kJ/mol)
k=k ₀₁exp(-E ₁ /RT)	$1.0628 × 107 m o l / g ? h ? M P a 2$	76.01
a=k ₀₂exp(-E ₂ /RT)	0.3899 MPa^-1/2	1.789
b=k ₀₃exp(-E ₃ /RT)	0.9853 MPa^-1	16.13
c=k ₀₄exp(-E ₄ /RT)	0.1715 MPa^-3/2	1.240

图3 催化剂床层温度计算值和实验值的比较

Fig.3 Comparison of calculated and experimental values of catalyst bed temperature

图4 球形蛋壳和均匀分布型催化剂H2摩尔分数

Fig.4 H2 molar fraction in egg-shell and common catalyst

图5 球形蛋壳和均匀分布型催化剂CO摩尔分数

Fig.5 CO molar fraction in egg-shell and common catalyst

图6 不同活性组分厚度催化剂颗粒内的反应物分布

Fig.6 Reactant distribution under different active component thickness

图7 活性组分厚度对催化剂颗粒内温度分布的影响

Fig.7 Effect of active component thickness on temperature distribution

图8 活性组分厚度对产物选择性和CO反应速率的影响

Fig.8 Effect of active component thickness on selectivity and CO reaction

参考文献 32

1	应卫勇, 曹发海, 房鼎业 . 碳一化工主要产品生产技术[M]. 北京: 化学工业出版社, 2004: 1-2.
	Ying W Y , Cao F H , Fang D Y . Production Technology of Major Products of C1 Chemical Industry[M]. Beijing: Chemical Industry Press, 2004: 1-2.
2	郝青青, 胥娜, 刘昭铁, 等 . 合成气一步法合成清洁汽油的研究进展[J].石油化工, 2009, 38(2): 207-219.
	Hao Q Q , Xu N , Liu Z T , et al . Recent advances in one-step synthesis of clean gasoline from syngas[J]. Petrochemical Technology, 2009, 38(2): 207-219.
3	Steynberg A P , Nel H G . Clean coal conversion options using Fischer-Tropsch technology[J]. Fuel, 2004, 83(6): 765-770.
4	Dry M E . Fischer-Tropsch reactions and the environment[J]. Appl. Catal, A: Gen., 1999, 189: 185-190.
5	Szybist J P , Kirby S R , Boehman A L . NO _x emissions of alternative diesel fuels: a comparative analysis of biodiesel and F-T diesel[J]. Energy Fuels, 2005, 19(4): 1484-l492.
6	王逸凝, 李永旺, 赵玉龙, 等 . 固定床费托（FT）合成单颗粒催化剂模拟[J]. 化学反应工程与工艺, 2000, 16(2): 109-115.
	Wang Y N , Li Y W , Zhao Y L , et al . Modeling of catalyst pellets for fixed-bed Fischer-Tropsch synthesis[J]. Chemical Reaction Engineering and Technology, 2000, 16(2): 109-115.
7	Flesich T H , Sills R A , Briscoe M D . 2002-emergence of the gas-to-liquids industry: a review of global GTL development[J]. Journal of Natural Gas Chemistry, 2002, 11: 1-14.
8	Kagyrrnanova A P , Zolotarskii I A , Smirnov E I , et al . Optimum dimensions of shaped steam reforming catalyst[J]. Chemical Engineering Journal, 2007, 134(1): 228-234.
9	Nguyen T T M , Wissing L , Skjøth R M S . High temperature methanation: catalyst consideration[J]. Catalysis Today, 2013, 215: 233-238.
10	Fan R R , Gan L , Zhu B C . Engineering research of irregular shape catalyst with through-hole(Ⅰ): Determination of equivalent diameters of pellets with 12 and 24 through-holes[J]. Journal of Chemical Industry and Engineering China, 2001, 52(2): 170-172.
11	Louisnard O , Frias F A , Tudela I , et al . Optimized design of an electrochemical filter-press reactor using CFD methods[J]. Chemical Engineering Journal, 2011, 169: 270-281.
12	Ekambara K , Nandakumar K , Joshi J B . CFD simulation of bubble column reactor using population balance[J]. Industrial & Engineering Chemistry Research, 2008, 47(21): 8505-8516.
13	Nijemeisland M , Dixon A G . Comparison of CFD simulations to experiment for convective heat transfer in a gas-solid fixed bed[J]. Chemical Engineering Journal, 2001, 82: 231-246.
14	Dixon A G , Nijemeisland M , Stitt E H . Packed tubular reactor modeling and catalyst design using computational fluid dynamics[J]. Advances in Chemical Engineering, 2006, 31(6): 307-389.
15	Nijemeisland M , Dixon A G , Stitt E H . Catalyst design by CFD for heat transfer and reaction in steam reforming[J]. Chemical Engineering Science, 2004, 59(2): 5185-5191.
16	Taskin M E , Dixon A G , Nijemeisland M , et al . CFD study of the influence of catalyst particle design on steam reforming reaction heat effects in narrow packed tubes [J]. Industrial & Engineering Chemistry Research, 2008, 47(16): 5966-5975.
17	罗青, 张莉, 曹军, 等 . 微通道下费托合成催化剂层涂覆厚度的数字模拟[J]. 化工进展, 2015, 34(3): 652-658.
	Luo Q , Zhang L , Cao J , et al . Numerical study on catalytic Fischer-Tropsch synthesis reaction in micro-channel[J]. Chemical Industry and Engineering Progress, 2015, 34(3): 652-658.
18	江宏玲, 肖军 . 串行流化床生物质气化费托（FT）合成的模拟[J]. 合肥工业大学学报, 2015, 38(10): 1396-1403.
	Jiang H L , Xiao J . Simulation of Fischer-Tropsch synthesis from biomass gasification in interconnected fluidized beds[J]. Journal of Hefei University of Technology, 2015, 38(10): 1396-1403.
19	鲁丰乐 . 费托合成催化剂反应动力学研究和反应器数学模拟[D]. 上海: 华东理工大学, 2010.
	Lu F L . Study on reaction kinetics of catalyst and mathematical simulation of reactor for Fischer-Tropsch synthesis[D]. Shanghai: East China University of Science and Technology, 2010.
20	Naseri A T , Peppley B A , Pharoah J G . Computational analysis of the reacting flow in a microstructured reformer using a multiscale approach[J]. AIChE Journal, 2014, 60(6): 2263-2274.
21	Taskin M E , Dixon A G , Stitt E H , et al . Approximation of reaction heat effects in cylindrical catalyst particles with Internal voids using CFD[J]. Chemical Engineering Faculty Publications, 2007, 5(1): 56-72.
22	Awdry S , Kolaczkowski S T , Chao R , et al . Application of a CFD code (FLUENT) to formulate models of catalytic gas phase reactions in porous catalyst pellets[J]. Chemical Engineering Research & Design, 2007, 85(11): 1539-1552.
23	王逸凝 . 固定床费托合成的模型化与模拟研究——动力学、单颗粒和反应器[D]. 太原: 中国科学院山西煤炭化学研究所, 2001.
	Wang Y N . Modeling and simulation of Fischer-Tropsch synthesis in fixed bed-kinetics, single particle and reactor[D]. Taiyuan: Institute of Coal Chemistry Chinese Academy of Sciences, 2001.
24	Taskin M E , Dixon A G , Stitt E H . CFD study of fluid flow and heat transfer in a fixed bed of cylinders[J]. Numerical Heat Transfer Part A : Applications, 2007, 52(3): 203-218.
25	Dixon A G , Boudreau J , Flow Rocheleau A. , transport, and reaction interactions in shaped cylindrical particles for steam methane reforming [J]. Industrial & Engineering Chemistry Research, 2012, 51(49): 15839-15854.
26	张杰, 李涛 . 甲烷化梅花状催化剂CFD计算及改进[J]. 化工学报, 2018, 69(7): 2985-2992.
	Zhang J , Li T . Application of CFD to improve the calculated process of methanation over plum-shaped catalyst[J]. CIESC Journal, 2018, 69(7): 2985-2992.
27	Dixon A G , Nijemeisland M , Stitt E H . Systematic mesh development for 3D CFD simulation of fixed beds: contact point study[J]. Computers & Chemical Engineering, 2013, 48: 135-153.
28	Dixon A G , Nijemeisland M , Stitt E H . Systematic mesh development for 3D CFD simulation of fixed beds: single sphere study[J]. Computers & Chemical Engineering, 2011, 35(7): 1171-1185.
29	Reid R C , Prausnitz J M , Poling B E . The Properities of Gases and Liquids[M]. New York: McGraw-Hill, 1987.
30	Smith D R . Thermal conductivity of fibrous glass board by guarded hot plates and heat flow meter an international round-robin[J]. International Journal of Thermophysics. 1997, 8(6): 1557-1573.
31	Wu J M , Zhang H T , Ying W Y , et al . Thermal conductivity of cobalt-based catalyst for Fischer-Tropsch synthesis[J]. International Journal of Thermophysics, 2010, 31(3): 556-571
32	鲁丰乐, 张海涛, 马向东, 等 . 钴基催化剂费托合成动力学模型[J]. 中国科技论文在线, 2009, 4(9): 632-637.
	Lu F L , Zhang H T , Ma X D , et al . Kinetics models of Fischer-Tropsch synthesis on the cobalt-based catalyst[J]. Sciencepaper Online, 2009, 4(9): 632-637.

[1]	张思雨, 殷勇高, 贾鹏琦, 叶威. 双U型地埋管群跨季节蓄热特性研究[J]. 化工学报, 2023, 74(S1): 295-301.
[2]	肖明堃, 杨光, 黄永华, 吴静怡. 浸没孔液氧气泡动力学数值研究[J]. 化工学报, 2023, 74(S1): 87-95.
[3]	李艺彤, 郭航, 陈浩, 叶芳. 催化剂非均匀分布的质子交换膜燃料电池操作条件研究[J]. 化工学报, 2023, 74(9): 3831-3840.
[4]	温凯杰, 郭力, 夏诏杰, 陈建华. 一种耦合CFD与深度学习的气固快速模拟方法[J]. 化工学报, 2023, 74(9): 3775-3785.
[5]	陈杰, 林永胜, 肖恺, 杨臣, 邱挺. 胆碱基碱性离子液体催化合成仲丁醇性能研究[J]. 化工学报, 2023, 74(9): 3716-3730.
[6]	杨学金, 杨金涛, 宁平, 王访, 宋晓双, 贾丽娟, 冯嘉予. 剧毒气体PH₃的干法净化技术研究进展[J]. 化工学报, 2023, 74(9): 3742-3755.
[7]	邢雷, 苗春雨, 蒋明虎, 赵立新, 李新亚. 井下微型气液旋流分离器优化设计与性能分析[J]. 化工学报, 2023, 74(8): 3394-3406.
[8]	杨菲菲, 赵世熙, 周维, 倪中海. Sn掺杂的In₂O₃催化CO₂选择性加氢制甲醇[J]. 化工学报, 2023, 74(8): 3366-3374.
[9]	李凯旋, 谭伟, 张曼玉, 徐志豪, 王旭裕, 纪红兵. 富含零价钴活性位点的钴氮碳/活性炭设计及甲醛催化氧化应用研究[J]. 化工学报, 2023, 74(8): 3342-3352.
[10]	岳林静, 廖艺涵, 薛源, 李雪洁, 李玉星, 刘翠伟. 凹坑缺陷对厚孔板喉部空化流动特性影响研究[J]. 化工学报, 2023, 74(8): 3292-3308.
[11]	杨欣, 彭啸, 薛凯茹, 苏梦威, 吴燕. 分子印迹-TiO₂光电催化降解增溶PHE废水性能研究[J]. 化工学报, 2023, 74(8): 3564-3571.
[12]	汪林正, 陆俞冰, 张睿智, 罗永浩. 基于分子动力学模拟的VOCs热氧化特性分析[J]. 化工学报, 2023, 74(8): 3242-3255.
[13]	余娅洁, 李静茹, 周树锋, 李清彪, 詹国武. 基于天然生物模板构建纳米材料及集成催化剂研究进展[J]. 化工学报, 2023, 74(7): 2735-2752.
[14]	何晓崐, 刘锐, 薛园, 左然. MOCVD生长AlN单晶薄膜的气相和表面化学反应综述[J]. 化工学报, 2023, 74(7): 2800-2813.
[15]	李盼, 马俊洋, 陈志豪, 王丽, 郭耘. Ru/α-MnO₂催化剂形貌对NH₃-SCO反应性能的影响[J]. 化工学报, 2023, 74(7): 2908-2918.