碱改性MIL-53（Cr）选择性吸附分离二甲苯异构体

doi:10.11949/0438-1157.20250004

摘要/Abstract

摘要：

MIL-53是一类吸附分离二甲苯异构体的重要材料，其中MIL-53(Cr)对邻二甲苯（OX）和对二甲苯（PX）具有较高的分离选择性，而对OX和间二甲苯（MX）选择性低。为了改善MIL-53(Cr)对OX和MX的选择性，利用碱前体KNO₃和金属中心Cr³⁺之间的氧化还原作用在MIL-53(Cr)上直接制备强碱性位点，以碱改性的MIL-53(Cr)为吸附剂，对OX、PX和MX进行液相吸附分离。结果表明，在MIL-53(Cr)中引入碱性位不改变材料的独特结构。由于引入的碱性位占用了部分金属位点，导致材料对二甲苯的吸附量有所下降。OX/PX的吸附选择性不变，而碱性位点的增加导致材料对MX的吸附阻力增大，吸附量减少，OX/MX的吸附选择性从MIL-53(Cr)的2.3提高到K-MIL-53(Cr)的4.1。K-MIL-53(Cr)具有良好的稳定性和再生能力，吸附循环5次，吸附量仅下降5.7%，且材料结构保持不变。

关键词: 碱性位点, 金属有机框架, 二甲苯异构体, 吸附分离, 选择性

Abstract:

MIL-53 is an important material for the adsorption and separation of xylene isomers, in which MIL-53(Cr) has high selectivity for o-xylene (OX) and p-xylene (PX), but low selectivity for OX and m-xylene (MX). To improve the selectivity of MIL-53(Cr) to OX and MX, a strong alkaline site was directly introduced into MIL-53(Cr) through a redox action between the base precursor KNO₃ and the metal center Cr³⁺. This alkali-modified MIL-53(Cr) was then tested as an adsorbent for the liquid-phase separation of OX, PX, and MX. The results show that the introduction of basic sites in MIL-53(Cr) does not alter the unique structure of the material. However, because the newly introduced alkaline sites partially occupy the metal sites, the adsorption capacity for xylene decreases. The adsorption selectivity for OX/PX remains unchanged, while the material's resistance to adsorption of MX increases with the density of basic sites, resulting in a decrease in overall adsorption capacity. Notably, the OX/MX adsorption selectivity improved from 2.3 for MIL-53(Cr) to 4.1 for the modified K-MIL-53(Cr). K-MIL-53(Cr) demonstrates excellent stability and regeneration ability. After five adsorption cycles, its adsorption capacity only decreased by 5.7%, and the structural integrity of the material remained largely unchanged.

Key words: alkaline sites, metal-organic framework, xylene isomer, adsorption separation, selectivity

中图分类号:

TQ 241.1

裴星亮, 叶翠平, 裴赢丽, 李文英. 碱改性MIL-53（Cr）选择性吸附分离二甲苯异构体[J]. 化工学报, 2025, 76(S1): 258-267.

Xingliang PEI, Cuiping YE, Yingli PEI, Wenying LI. Selective adsorption and separation of xylene isomers by alkali-modified MIL-53(Cr)[J]. CIESC Journal, 2025, 76(S1): 258-267.

图/表 11

图1 MIL-53(Cr)和K-MIL-53(Cr)的XRD谱图(a)和FTIR谱图(b)

Fig.1 XRD patterns (a) and FTIR spectra (b) of MIL-53(Cr) and K-MIL-53(Cr)

图2 MIL-53(Cr)和K-MIL-53(Cr)的SEM-EDS图

Fig.2 SEM images and EDS mapping of MIL-53(Cr) and K-MIL-53(Cr)

图3 单组分二甲苯在(a)MIL-53(Cr)和(b)K-MIL-53(Cr)上吸附量随时间的变化；(c) K-MIL-53(Cr)二甲苯吸附过程的准二级动力学模型拟合

Fig.3 Time-dependent adsorption of single-component xylene on (a)MIL-53(Cr) and (b)K-MIL-53(Cr)；(c) Quasi-second-order kinetic model fitting for the xylene adsorption process of K-MIL-53(Cr)

表1 K-MIL-53（Cr）吸附二甲苯异构体的动力学拟合参数

Table 1 Kinetic fitting results of xylene isomers adsorption on K-MIL-53（Cr）

二甲苯	C₀/(mol·L^-1)	准一级动力学模型 $l n Q e - Q = l n Q e - k 1 t$			准二级动力学模型 $t Q = 1 k 2 Q e 2 + t Q e$
二甲苯	C₀/(mol·L^-1)	k₁/(g·mg^-1·h^-1)	Q_e/(mg·g^-1)	R²	k₂/(g·mg^-1·h^-1)	Q_e/(mg·g^-1)	R²
OX	0.5	0.0773	138.02	0.7887	0.0005	497.51	0.9979
MX	0.5	0.0600	24.05	0.6740	0.0101	164.21	0.9996
PX	0.5	0.0601	27.39	0.6666	0.0291	187.82	0.9995

表1 K-MIL-53（Cr）吸附二甲苯异构体的动力学拟合参数

Table 1 Kinetic fitting results of xylene isomers adsorption on K-MIL-53（Cr）

二甲苯	C₀/(mol·L^-1)	准一级动力学模型 $l n Q e - Q = l n Q e - k 1 t$			准二级动力学模型 $t Q = 1 k 2 Q e 2 + t Q e$
二甲苯	C₀/(mol·L^-1)	k₁/(g·mg^-1·h^-1)	Q_e/(mg·g^-1)	R²	k₂/(g·mg^-1·h^-1)	Q_e/(mg·g^-1)	R²
OX	0.5	0.0773	138.02	0.7887	0.0005	497.51	0.9979
MX	0.5	0.0600	24.05	0.6740	0.0101	164.21	0.9996
PX	0.5	0.0601	27.39	0.6666	0.0291	187.82	0.9995

图4 (a) 25℃下K-MIL-53(Cr)对单组分二甲苯的吸附性能；(b)温度的影响；(c) Langmuir拟合曲线

Fig.4 (a) Single component adsorption of K-MIL-53(Cr) for xylene at 25℃; (b) Impact of temperature; (c) Langmuir adsorption isotherm fitting curves

表2 K-MIL-53（Cr）上单组分二甲苯的Langmuir和Freundlich吸附等温线拟合参数

Table 2 Parameters of Langmuir and Freundlich adsorption model for single-xylene isomer on K-MIL-53（Cr）

吸附质	温度/℃	Langmuir吸附等温线 $Q e = Q m K L C e 1 + K L C e$			Freundlich吸附等温线 $Q e = K F C e 1 n$
吸附质	温度/℃	Q_m/(mg·g^-1)	K_L/(L·mol^-1)	R²	K_F/(mg·g^-1·(L·mol^-1)^1/ⁿ )	$1 n$	R²
OX	25	581.39	11.23	0.9985	562.34	0.23	0.9506
MX	25	164.20	6.91	0.9913	175.27	0.31	0.9007
PX	25	187.70	7.86	0.9962	213.87	0.37	0.9612

表2 K-MIL-53（Cr）上单组分二甲苯的Langmuir和Freundlich吸附等温线拟合参数

Table 2 Parameters of Langmuir and Freundlich adsorption model for single-xylene isomer on K-MIL-53（Cr）

吸附质	温度/℃	Langmuir吸附等温线 $Q e = Q m K L C e 1 + K L C e$			Freundlich吸附等温线 $Q e = K F C e 1 n$
吸附质	温度/℃	Q_m/(mg·g^-1)	K_L/(L·mol^-1)	R²	K_F/(mg·g^-1·(L·mol^-1)^1/ⁿ )	$1 n$	R²
OX	25	581.39	11.23	0.9985	562.34	0.23	0.9506
MX	25	164.20	6.91	0.9913	175.27	0.31	0.9007
PX	25	187.70	7.86	0.9962	213.87	0.37	0.9612

图5 25℃时MIL-53(Cr)和K- MIL-53(Cr)对二甲苯的吸附量及选择性

Fig.5 Xylene adsorption capacity of MIL-53(Cr) and K-MIL-53 (Cr) at 25℃

图6 (a) K- MIL-53(Cr)在25℃下对二甲苯的吸附循环性能; (b) 5次吸附循环后K-MIL-53(Cr)的XRD谱图

Fig.6 (a) Cycle performance of K-MIL-53(Cr) at 25℃; (b) XRD pattern of K-MIL-53(Cr) after 5 cycles

图7 (a) MIL-53(Cr)和K-MIL-53(Cr)在77 K下的N2吸脱附等温线；(b) MIL-53(Cr)和K-MIL-53(Cr)的微孔孔径分布

Fig.7 (a) N2 adsorption and desorption isotherms of MIL-53(Cr) and K-MIL-53(Cr) at 77 K;(b) Micropore size distribution of MIL-53(Cr) and K-MIL-53(Cr)

表3 MIL-53（Cr）和K-MIL-53 （Cr）的BET比表面积、孔体积和最可几孔径

Table 3 BET specific surface area， pore volume and most probable aperture of MIL-53（Cr） and K-MIL-53 （Cr）

Item	MIL-53(Cr)	K-MIL-53(Cr)
specific surface area（N₂）/(m²·g^-1)	1004	832
pore volume/(cm³·g^-1)	0.53	0.49
most probable aperture/nm	0.69	0.69

图8 MIL-53(Cr)和K-MIL-53(Cr)的XPS谱图

Fig.8 XPS spectra of MIL-53(Cr) and K-MIL-53(Cr)

参考文献 32

1	Yousefzadeh Borzehandani M, Abdulmalek E, Abdul Rahman M B, et al. First-principles investigation of dimethyl-functionalized MIL-53(Al) metal-organic framework for adsorption and separation of xylene isomers[J]. Journal of Porous Materials, 2021, 28(2): 579-591.
2	Yang Y, Bai P, Guo X. Separation of xylene isomers: a review of recent advances in materials[J]. Industrial & Engineering Chemistry Research, 2017, 56(50): 14725-14753.
3	刘莹, 郑芳, 杨启炜, 等. 二甲苯异构体吸附分离研究进展[J]. 化工学报, 2024, 75(4): 1081-1095.
	Liu Y, Zheng F, Yang Q W, et al. Recent progress in adsorption and separation of xylene isomers [J].CIESC Journal, 2024, 75(4): 1081-1095.
4	郝西维, 刘秋芳, 刘弓, 等. 对二甲苯生产技术开发进展及展望[J]. 洁净煤技术, 2016, 22(5): 25-30.
	Hao X W, Liu Q F, Liu G, et al. Progress and prospect of p‐xylene production technologies[J]. Clean Coal Technology, 2016, 22(5): 25-30.
5	Gonzalez M I, Kapelewski M T, Bloch E D, et al. Separation of xylene isomers through multiple metal site interactions in metal-organic frameworks[J]. Journal of the American Chemical Society, 2018, 140(9): 3412-3422.
6	钱庆玲. 大环衍生多孔有机聚合物吸附分离二甲苯异构体的研究[D]. 合肥: 中国科学技术大学, 2023.
	Qian Q L. Adsorption separation of xylene lsomers by macrocycle-based porous organic polymers[D]. Hefei: University of Science and Technology of China, 2023.
7	Torres-Knoop A, Krishna R, Dubbeldam D. Separating xylene isomers by commensurate stacking of p‐xylene within channels of MAF‐X8[J]. Angewandte Chemie International Edition, 2014, 53(30): 7774-7778.
8	Moreira M A, Santos J C, Ferreira A F P, et al. Selective liquid phase adsorption and separation of ortho-xylene with the microporous MIL-53(Al) [J]. Separation Science and Technology, 2011, 46(13): 1995-2003.
9	Khosravi-Nikou M, Shahmoradi A, Shariati A, et al. Experimental and techno-economic investigation of industrial para-xylene plant revamping to produce meta-xylene [J]. Scientific Reports, 2023, 13(1): 12534.
10	Lippi M, Cametti M. Highly dynamic 1D coordination polymers for adsorption and separation applications [J]. Coordination Chemistry Reviews, 2021, 430: 213661.
11	Li L, Guo L, Olson D H, et al. Discrimination of xylene isomers in a stacked coordination polymer [J]. Science, 2022, 377(6603): 335-339.
12	Lannoeye J, van de Voorde B, Bozbiyik B, et al. An aliphatic copper metal-organic framework as versatile shape selective adsorbent in liquid phase separations[J]. Microporous and Mesoporous Materials, 2016, 226: 292-298.
13	Sui H, Jiang P, Li X, et al. Binary adsorption equilibrium and breakthrough of n-butyl acetate and p-xylene on granular activated carbon[J]. Industrial & Engineering Chemistry Research, 2019, 58(19): 8279-8289.
14	Yu L, Zhang J, Ullah S, et al. Separating xylene isomers with a calcium metal-organic framework[J]. Angewandte Chemie International Edition, 2023, 62(41): 130-135.
15	Yao J, Chen Q, Sheng Y, et al. pH-controlled crystal growth of copper/gemini surfactant complexes with bipyridine groups [J]. Crystengcomm, 2017, 19(39): 5835-5843.
16	Zhang C, Qin Y, Duan L, et al. pH-dependent formation of three porous In(Ⅲ)-MOFs: framework diversity and selective gas adsorption [J]. Dalton Transactions, 2022, 51(2): 473-477.
17	Zhao M, Yuan K, Wang Y, et al. Metal-organic frameworks as selectivity regulators for hydrogenation reactions [J]. Nature, 2016, 539(7627): 76-80.
18	Reinsch H, Stassen I, Bueken B, et al. First examples of aliphatic zirconium MOFs and the influence of inorganic anions on their crystal structures [J]. Crystengcomm, 2015, 17(2): 331-337.
19	Khudozhitkov A E, Jobic H, Freude D, et al. Ultraslow dynamics of a framework linker in MIL-53 (Al) as a sensor for different isomers of xylene [J]. The Journal of Physical Chemistry C, 2016, 120(38): 21704-21709.
20	Lu P, Yu D, Lu J.A method for modifying dynamically classes in the object-oriented dynamic programming environment[J]. ACM SIGPLAN Notices, 1997, 32(9): 57-60.
21	Yang H, Hu Y. Separation of para-xylene and meta-xylene by extraction process using aqueous cyclodextrins solution [J]. Chemical Engineering and Processing-Process Intensification, 2017, 116: 114-120.
22	Serre C, Millange F, Thouvenot C, et al. Very large breathing effect in the first nanoporous chromium(Ⅲ)-based solids: MIL-53 or Cr^Ⅲ(OH)·{O₂C-C₆H₄-CO₂}·{HO₂C-C₆H₄-CO₂H} _x ·H₂O _y [J]. Journal of the American Chemical Society, 2002, 124(45): 13519-13526.
23	Moïse J C, Bellat J P. Effect of preadsorbed water on the adsorption of p-xylene and m-xylene mixtures on BaX and BaY zeolites [J]. Journal of Physical Chemistry B, 2005, 109(36): 17239-17244.
24	Li Y X, Jiang W J, Tan P, et al. What matters to the adsorptive desulfurization performance of metal-organic frameworks? [J]. Journal of Physical Chemistry C, 2015, 119(38): 21969-21977.
25	Liu X, Pang H, Liu X, et al. Orderly porous covalent organic frameworks-based materials: superior adsorbents for pollutants removal from aqueous solutions [J]. The Innovation, 2021, 2(1): 100076-100104.
26	He Z, Yang Y, Bai P, et al. Metal-organic framework MIL-53(Cr) as a superior adsorbent: highly efficient separation of xylene isomers in liquid phase [J]. Journal of Industrial and Engineering Chemistry, 2019, 77: 262-272.
27	Ren J, Musyoka N M, Langmi H W, et al. Modulated synthesis of chromium-based metal-organic framework (MIL-101) with enhanced hydrogen uptake [J]. International Journal of Hydrogen Energy, 2014, 39(23): 12018-12023.
28	Mounfield W P, Walton K S. Effect of synthesis solvent on the breathing behavior of MIL-53(Al) [J]. Journal of Colloid and Interface Science, 2015, 447: 33-39.
29	Ortiz G, Chaplais G, Paillaud J-L, et al. New insights into the hydrogen bond network in Al-MIL-53 and Ga-MIL-53 [J]. The Journal of Physical Chemistry C, 2014, 118(38): 22021-22029.
30	Liu W, Zhu L, Jiang Y, et al. Direct fabrication of strong basic sites on ordered nanoporous materials: exploring the possibility of metal-organic frameworks [J]. Chemistry of Materials, 2018, 30(5): 1686-1694.
31	Rasouli M, Yaghobi N, Chitsazan S, et al. Effect of nanocrystalline zeolite Na-Y on meta-xylene separation [J]. Microporous and Mesoporous Materials, 2012, 152: 141-147.
32	Jiang J, Sandler S I. Shape versus inverse-shape selective adsorption of alkane isomers in carbon nanotubes [J]. The Journal of Chemical Physics, 2006, 124(2): 024717.

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