Effects of industrial catalyst structure on methanol to aromatics in a packed bed reactor

doi:10.11949/0438-1157.20250378

Abstract

Abstract:

Methanol to aromatics is a feasible process to produce aromatics without using petroleum as feedstock, and the key to this process is developing high-performance industrial catalysts. This work builds a two-scale particle-resolved computational fluid dynamics model that describes transfer and reaction from industrial catalyst particle to packed bed reactor, considering the transfer process at the reactor scale would affect the overall performance of industrial catalysts. With this two-scale model, the effects of industrial catalyst structure on methanol to aromatics are investigated. The results show that the Raschig ring catalyst particles have a large bed void ratio and small diffusion restriction in the catalyst. Compared with other catalyst shapes, they have the lowest bed pressure drop and higher reactor outlet aromatics yield. Reducing catalyst particle size is effective in increasing the aromatic yield at reactor outlet, but significantly rises the pressure drop. The catalyst with 200 nm pore size and 0.5 porosity can effectively balance internal diffusion as well as catalyst amount and active site distribution, and thus its corresponding catalyst bed shows the highest aromatic yield at reactor outlet. These results in this work provide a powerful model and some important theoretical guidance for the development of industrial catalysts for methanol to aromatics.

Key words: methanol to aromatics, porous media, packed bed, computational fluid dynamics, transport

摘要：

甲醇制芳烃是一种可行的替代石油路线的芳烃生产技术，其关键在于开发高性能甲醇制芳烃工业催化剂。考虑到反应器尺度传递过程会影响工业催化剂的整体性能，建立了从工业催化剂到固定床反应器的双尺度颗粒分辨计算流体力学模型，并借助该模型探究了工业催化剂结构对甲醇制芳烃性能的影响规律。结果显示，拉西环催化剂颗粒对应的床层空隙率大，催化剂内扩散限制小，相比于其他催化剂外形具有最低的床层压降和较高的反应器出口芳烃收率。减小催化剂颗粒粒径能有效提升反应器出口芳烃收率，但是也会显著增加反应器压降。催化剂孔径为200 nm以及空隙率为0.5时能有效平衡催化剂内扩散以及催化材料含量和分布，显示出最高的反应器出口芳烃收率。研究结果将为甲醇制芳烃工业催化剂设计优化提供一种强大的模型工具以及一些重要的理论依据。

关键词: 甲醇制芳烃, 多孔介质, 填充床, 计算流体力学, 传递

CLC Number:

TQ 021.4

Qinqin XIE, Junqi WENG, Zhenli LIN, Guanghua YE, Xinggui ZHOU. Effects of industrial catalyst structure on methanol to aromatics in a packed bed reactor[J]. CIESC Journal, 2025, 76(9): 4487-4498.

解勤勤, 翁俊旗, 林振利, 叶光华, 周兴贵. 固定床反应器中甲醇制芳烃工业催化剂结构影响的研究[J]. 化工学报, 2025, 76(9): 4487-4498.

Figures/Tables 12

Fig.1 Reaction network of methanol to aromatics[25]

Table 1 Parameters for the lumped kinetics model［25］

反应编号 i	活化能 $E a i$ /(J/mol)	指前因子A_i /h^-1
1	2.08×10⁴	1.61×10³
2	6.99×10⁴	3.64×10⁶
3	7.87×10³	1.46×10²
4	2.17×10⁴	1.13×10³
5	6.05×10³	1.06×10²
6	5.98×10⁴	1.45×10⁶

Table 1 Parameters for the lumped kinetics model［25］

反应编号 i	活化能 $E a i$ /(J/mol)	指前因子A_i /h^-1
1	2.08×10⁴	1.61×10³
2	6.99×10⁴	3.64×10⁶
3	7.87×10³	1.46×10²
4	2.17×10⁴	1.13×10³
5	6.05×10³	1.06×10²
6	5.98×10⁴	1.45×10⁶

Fig.2 Structures of the meshes (a), and mesh sensitivity analysis (b)

Table 2 Simulation parameters in this work

参数	数值
入口速度u_in/(m/s)	0.2
压力P_in/MPa	0.1
入口温度T_in/K	630
壁温T_wall/K	630
催化剂孔隙率ε_cat	0.5
催化剂孔径d_p/nm	20
催化剂直径d_s/mm	8
催化剂密度ρ_s/(kg/m³)	2230
反应管直径d_t/mm	40
床层高度L/mm	110

Fig.3 Comparison of the pressure drops in a catalyst bed calculated by the model in this work and obtained from experiments[39]

Fig.4 Bed voidages and pressure drops (a), conversions of methanol and dimethyl ether (lumped component a) and yields of aromatics at reactor outlet (b), axial (c) and radial bed voidages under different tube diameters (d)

Fig.5 Distributions of fluid velocity magnitude(a), temperature (b) and concentration of aromatics (c) under different tube diameters

Fig.6 Voidages and pressure drops (a), velocity magnitude distributions (b), conversions of lumped component a and yields of aromatics (c), and concentration distribution of aromatics (d) for the beds packed with catalyst particles of different shapes

Table 3 Structural parameters of catalyst particles of different shapes

尺寸

d = 8.00 mm

d = 6.53 mm，

l = 8.00 mm

d_out = 7.54 mm，

d_in = 3.77 mm，

l = 8.00 mm

d = 6.98 mm，

l = 8.00 mm

d_out = 7.54 mm，

d_in = 1.89 mm，

l = 8.00 mm

Fig.7 Voidages and pressure drops (a), conversions of lumped component a and yields of aromatics (b), axial (c) and radial bed voidages (d), velocity magnitude distributions (e), and concentration distribution of aromatics (f) for the beds packed with catalyst particles of different sizes

Fig.8 Conversions of lumped component a and yields of aromatics at reactor outlet (a), and concentration distributions of aromatics (b) for the beds packed with catalyst particles of different pore diameters

Fig.9 Conversions of lumped component a and yields of aromatics at reactor outlet (a), and concentration distributions of aromatics (b) for the beds packed with catalyst particles of different porosities

References 43

[1]	杜浩帆. 改性ZSM-5分子筛上甲醇芳构化动力学研究[D]. 北京: 北京化工大学, 2023.
	Du H F. Kinetics of methanol aromatization on modified ZSM-5 molecular sieve[D]. Beijing: Beijing University of Chemical Technology, 2023.
[2]	Ali S S, Zaidi H A. Experimental and kinetic modeling studies of methanol transformation to hydrocarbons using zeolite-based catalysts: a review[J]. Energy & Fuels, 2020, 34(11): 13225-13246.
[3]	Olsbye U, Svelle S, Lillerud K P, et al. The formation and degradation of active species during methanol conversion over protonated zeotype catalysts[J]. Chemical Society Reviews, 2015, 44(20): 7155-7176.
[4]	张宝珠. 甲醇转化制芳烃(MTA)反应的研究[D]. 大连: 大连理工大学, 2013.
	Zhang B Z. Study on the reaction of methanol conversion to aromatic hydrocarbons (MTA)[D]. Dalian: Dalian University of Technology, 2013.
[5]	Janssens T V W. A new approach to the modeling of deactivation in the conversion of methanol on zeolite catalysts[J]. Journal of Catalysis, 2009, 264(2): 130-137.
[6]	陈诗瑶, 申峻, 王玉高, 等. 甲醇制芳烃反应及生产工艺研究进展[J]. 现代化工, 2022, 42(2): 57-60, 67.
	Chen S Y, Shen J, Wang Y G, et al. Progress in reaction and production process for methanol to aromatics[J]. Modern Chemical Industry, 2022, 42(2): 57-60, 67.
[7]	Bi Y, Wang Y L, Chen X, et al. Methanol aromatization over HZSM-5 catalysts modified with different zinc salts[J]. Chinese Journal of Catalysis, 2014, 35(10): 1740-1751.
[8]	Zhang J G, Qian W Z, Kong C Y, et al. Increasing para-xylene selectivity in making aromatics from methanol with a surface-modified Zn/P/ZSM-5 catalyst[J]. ACS Catalysis, 2015, 5(5): 2982-2988.
[9]	Vicente H, Aguayo A T, Castaño P, et al. Dual-cycle-based lumped kinetic model for methanol-to-aromatics (MTA) reaction over H-ZSM-5 zeolites of different Si/Al ratio[J]. Fuel, 2024, 361: 130704.
[10]	代成义, 陈中顺, 杜康, 等. 甲醇制芳烃催化剂及相关工艺研究进展[J]. 化工进展, 2020, 39(12): 5029-5041.
	Dai C Y, Chen Z S, Du K, et al. Research progress of catalysts and related technologies for methanol to aromatics[J]. Chemical Industry and Engineering Progress, 2020, 39(12): 5029-5041.
[11]	许雄飞, 刘鹏龙, 张玮, 等. 两段法固定床甲醇制芳烃产物预测多元非线性回归模型[J]. 化工学报, 2022, 73(2): 838-846.
	Xu X F, Liu P L, Zhang W, et al. Multivariate nonlinear regression model of methanol to aromatics by two-state fixed bed for product prediction[J]. CIESC Journal, 2022, 73(2): 838-846.
[12]	Partopour B, Dixon A G. 110th anniversary: commentary: CFD as a modeling tool for fixed bed reactors[J]. Industrial & Engineering Chemistry Research, 2019, 58(14): 5733-5736.
[13]	Weng J Q, Akbar A, Deng Q H, et al. Enhanced performance of packed bed methane dry reformers using metal foam catalyst pellets: a particle resolved CFD study[J]. Chemical Engineering Science, 2024, 290: 119897.
[14]	翁俊旗, 刘鑫磊, 余佳豪, 等. 蜂窝状催化剂中空结构对固定床反应器压降的影响[J]. 化工学报, 2022, 73(1): 266-274.
	Weng J Q, Liu X L, Yu J H, et al. The impact of the hollow structure of honeycomb catalysts on pressure drop in fixed-bed reactors[J]. CIESC Journal, 2022, 73(1): 266-274.
[15]	Sadeghi M A, Aghighi M, Barralet J, et al. Pore network modeling of reaction-diffusion in hierarchical porous particles: the effects of microstructure[J]. Chemical Engineering Journal, 2017, 330: 1002-1011.
[16]	Zhang Q F, Weng J Q, Yu Q H, et al. Computational design of pore structure in heavy paraffin dehydrogenation catalyst pellets[J]. Industrial & Engineering Chemistry Research, 2022, 61(32): 11666-11677.
[17]	Dixon A G. Heat transfer in fixed beds at very low (<4) tube-to particle diameter ratio[J]. Industrial & Engineering Chemistry Research, 1997, 36: 3053-3064.
[18]	Wehinger G D, Kraume M, Berg V, et al. Investigating dry reforming of methane with spatial reactor profiles and particle-resolved CFD simulations[J]. AIChE Journal, 2016, 62(12): 4436-4452.
[19]	Schulze S, Nikrityuk P, Compart F, et al. Particle-resolved numerical study of char conversion processes in packed beds[J]. Fuel, 2017, 207: 655-662.
[20]	Dong Y, Geske M, Korup O, et al. What happens in a catalytic fixed-bed reactor for n-butane oxidation to maleic anhydride? Insights from spatial profile measurements and particle resolved CFD simulations[J]. Chemical Engineering Journal, 2018, 350: 799-811.
[21]	Pashchenko D, Karpilov I, Mustafin R. Numerical calculation with experimental validation of pressure drop in a fixed-bed reactor filled with the porous elements[J]. AIChE Journal, 2020, 66(5): e16937.
[22]	Wehinger G D, Kolaczkowski S T, Schmalhorst L, et al. Modeling fixed-bed reactors from metal-foam pellets with detailed CFD[J]. Chemical Engineering Journal, 2019, 373: 709-719.
[23]	Jurtz N, Kraume M, Wehinger G D. Advances in fixed-bed reactor modeling using particle-resolved computational fluid dynamics (CFD)[J]. Reviews in Chemical Engineering, 2019, 35(2): 139-190.
[24]	Bai H, Theuerkauf J, Gillis P A, et al. A coupled DEM and CFD simulation of flow field and pressure drop in fixed bed reactor with randomly packed catalyst particles[J]. Industrial & Engineering Chemistry Research, 2009, 48(8): 4060-4074.
[25]	Yang F, Jia X Z, Xu R, et al. Kinetic modelling of methanol transformation into p-xylene on a 3Zn-3Si/ZSM-5 catalyst[J]. New Journal of Chemistry, 2023, 47(4): 1973-1978.
[26]	Bender J, Erleben K, Trinkle J. Interactive simulation of rigid body dynamics in computer graphics[J]. Computer Graphics Forum, 2014, 33(1): 246-270.
[27]	Moghaddam E M, Foumeny E A, Stankiewicz A I, et al. Rigid body dynamics algorithm for modeling random packing structures of nonspherical and nonconvex pellets[J]. Industrial & Engineering Chemistry Research, 2018, 57(44): 14988-15007.
[28]	Kehoe J P G, Aris R. Communications on the theory of diffusion and reaction: (Ⅸ): Internal pressure and forced flow for reactions with volume change[J]. Chemical Engineering Science, 1973, 28(11): 2094-2098.
[29]	Wakao N, Smith J M. Diffusion and reaction in porous catalysts[J]. Industrial & Engineering Chemistry Fundamentals, 1964, 3(2): 123-127.
[30]	Pollard W G, Present R D. On gaseous self-diffusion in long capillary tubes[J]. Physical Review, 1948, 73(7): 762-774.
[31]	Wilke C R. Diffusional properties of multicomponent gases[J]. Chemical Engineering Progress, 1950, 46: 95-104.
[32]	Fuller E N, Schettler P, Giddings J. New method for prediction of binary gas-phase diffusion coefficients[J]. Industrial & Engineering Chemistry Research, 1967, 58(5): 18-27.
[33]	Poling B E, Prausnitz J M, O'Commell J P. The Properties of Gases and Liquids[M]. 5th ed. New York: McGraw-Hill, 2001.
[34]	Yeh T S, Sacks M D. Effect of particle size distribution on the sintering of alumina[J]. Journal of the American Ceramic Society, 1988, 71(12): C-484-C-487.
[35]	Eppinger T, Wehinger G D, Jurtz N, et al. A numerical optimization study on the catalytic dry reforming of methane in a spatially resolved fixed-bed reactor[J]. Chemical Engineering Research and Design, 2016, 115: 374-381.
[36]	Markatos N C. The mathematical modelling of turbulent flows[J]. Applied Mathematical Modelling, 1986, 10(3): 190-220.
[37]	Dixon A G, Taskin M E, Nijemeisland M, et al. CFD method to couple three-dimensional transport and reaction inside catalyst particles to the fixed bed flow field[J]. Industrial & Engineering Chemistry Research, 2010, 49(19): 9012-9025.
[38]	Boccardo G, Augier F, Haroun Y, et al. Validation of a novel open-source work-flow for the simulation of packed-bed reactors[J]. Chemical Engineering Journal, 2015, 279: 809-820.
[39]	Pashchenko D. Flow dynamic in a packed bed filled with Ni-Al₂O₃ porous catalyst: experimental and numerical approach[J]. AIChE Journal, 2019, 65(5): e16558.
[40]	Liu X L, Qin B, Zhang Q F, et al. Optimizing catalyst supports at single catalyst pellet and packed bed reactor levels: a comparison study[J]. AIChE Journal, 2021, 67(8): e17163.
[41]	Zhokh A, Strizhak P. Thiele modulus having regard to the anomalous diffusion in a catalyst pellet[J]. Chaos, Solitons & Fractals, 2018, 109: 58-63.
[42]	Wang G, Johannessen E, Kleijn C R, et al. Optimizing transport in nanostructured catalysts: a computational study[J]. Chemical Engineering Science, 2007, 62(18/19/20): 5110-5116.
[43]	Johannessen E, Wang G, Coppens M O. Optimal distributor networks in porous catalyst pellets(I): Molecular diffusion[J]. Industrial & Engineering Chemistry Research, 2007, 46(12): 4245-4256.