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摘要: 为了考察多级孔丝光沸石中介孔的存在对丝光沸石吸附平衡和动力学的影响，选择甲苯分子作为探针分子，对其在具有不同介孔孔隙度的多级孔丝光沸石上的吸附等温线和吸附动力学曲线进行了测试。结果表明，甲苯在多级孔丝光沸石上的吸附等温线可以很好地用双位Toth吸附模型进行描述，由拟合参数以及亨利常数（KH）和初始吸附热（Qst）的计算得知，相对于微孔丝光沸石，介孔的引入增大了甲苯在丝光沸石内的吸附量，但减弱了甲苯与沸石表面的相互作用力；另外，甲苯在多级孔沸石表现出高的吸附速率，并随介孔孔隙度的增加而增大，反映了沸石内介孔的存在可有效促进沸石的传质能力。
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关键词:
- 多级孔丝光沸石 /
- 甲苯 /
- 吸附等温线 /
- 吸附动力学 /
- 双位Toth吸附模型
Abstract: The adsorption isotherms and kinetic curves of toluene on a series of hierarchical mordenite zeolites with different mesoporosities were measured to investigate the effect of hierarchical pore structures of mordenite on the adsorption and kinetics. The isotherms of hierarchical mordenites show the combination of characteristics of both micropore and mesopore adsorption. Furthermore, the fitting of experimental isothermal data of toluene reveals that the isotherms of toluene can be well described by dual-sites Toth-type model. The fitting parameters and the Henry's constants (KH) and the initial heats of adsorption (Qst) calculated show that the introduction of mesopores into mordenite weakens the interaction between toluene and zeolitic surface. Additionally, the adsorption kinetic curves show that the adsorption rates of toluene on hierarchical mordenite are much larger than that on microporous mordenite, revealing the enhanced effect of mesopore on the mass transfer in zeolites. -
图 1 不同温度下甲苯在丝光沸石上的吸附等温线
Figure 1 Adsorption isotherms of toluene on mordenite at different temperatures
图 2 压力在0.15-0.20 kPa时甲苯在丝光沸石上的吸附动力学曲线
Figure 2 Adsorption kinetics of toluene on mordenite under pressure range of 0.15-0.20 kPa
图 3 甲苯在丝光沸石上的吸附速率k和丝光沸石介孔体积vmeso之间的关系
Figure 3 Relationship between the adsorption rate constant (k) of toluene on mordenite and the mesoporous volume (vmeso) of mordenite
表 1 甲苯在丝光沸石上的吸附等温线双位Toth模型拟合参数
Table 1 Dual-site Toth model fitting parameters of toluene on mordenites
Parameter MOR-0 MOR-1 MOR-2 MOR-3 qs1, 0 /(mmol·g-1) 0.74 0.70 0.68 0.66 χ1 1.41 0.68 0.13 0.56 b1, 0/(kPa-1) 1230 1070 840 760 Q1/(kJ·mol-1) 15.87 12.01 9.52 8.09 t1, 0 0.53 0.88 0.46 0.51 α1 1.71 0.88 0.79 1.31 qs2, 0/(mmol·g-1) 0.02 1.11 1.67 1.92 χ2 0.01 0.31 4.85 7.98 b2, 0/(kPa-1) 1.5 0.7 0.4 0.3 Q2/(kJ·mol-1) 13.71 12.82 7.41 4.67 t2, 0 0.68 0.46 0.63 1.37 α2 0.65 0.10 0.01 0.24 
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表 2 甲苯在丝光沸石上的亨利常数和初始吸附热
Table 2 Henry's constants and initial heats of adsorption for toluene on mordenite samples
Sample T/K KH/(mmol·g-1·kPa-1) Qst/(kJ·mol-1) MOR-0 293 4.02×105 82.7 308 1.46×105 323 5.96×104 MOR-1 293 2.99×104 67.8 308 1.62×104 323 6.60×103 MOR-2 293 4.16×103 57.4 308 2.28×103 323 1.25×103 MOR-3 293 1.64×103 46.4 308 0.86×103 323 0.61×103
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