摘要
采用改进型Wicke-Kallenbath稳态扩散池,在373~413 K及0.4~1.0 MPa条件下测定了氢气在某工业催化剂Cu O/Zn O/γ-Al2O3内部的有效扩散系数。实验采用逐步增加环己烷流量至某最大值而后逐步降低回到初始点的方法,测定了催化剂孔内发生毛细凝聚时氢气有效扩散系数随环己烷蒸气相对压力的变化。实验结果表明：在373 K下环己烷蒸气相对压力为0.42时开始发生毛细凝聚,而在413 K下则延迟到0.6才开始出现这一现象。此外,滞后环宽度随着温度的升高而变窄,并且氢气的有效扩散系数随环己烷蒸气相对压力变化出现多重滞后环。建立了催化剂部分润湿时氢气的有效扩散系数与内部润湿分率的关联式,与实验测量值符合较好。
The effective diffusivity of hydrogen in an industrial catalyst Cu O/Zn O/γ-Al2O3 pellet was measured with a modified Wicke-Kallenbath steady-state diffusion cell at 373 to 413 K and 0.4 to 1.0 MPa. Through changing the flow rate of cyclohexane in a sequence from low to high to a maximum and then vice versa, the effect of relative vapor pressure of cyclohexane on the effective diffusivity of hydrogen was investigated in the presence of capillary condensation within the catalyst pores. Condensation started at the relative vapor pressure of cyclohexane of 0.42 at 373 K, while it was delayed to the relative vapor pressure of 0.6 at 413 K. Besides, shrinking of hysteresis loops was observed with the increase of temperature, and the effective diffusivity of hydrogen also displayed multiple hysteresis loops with respect to the relative vapor pressure of cyclohexane. A correlation between the effective diffusivity of hydrogen and catalyst internal wetting fraction was proposed, and it showed good agreement between calculation and experimental data.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2015年第4期1363-1369,共7页
CIESC Journal
基金
国家自然科学基金项目(20876043
21076072)
华东理工大学交叉学科与重大项目培育基金(WA1113008)~~
关键词
毛细凝聚
有效扩散系数
多孔介质
内扩散
滞后环
capillary condensation
effective diffusivity
porous media
internal diffusion
hysteresis loop
