应用单粒子扩散反应器对甲烷在4A沸石中扩散的研究

DIFFUSION OF CH_4 IN 4A ZEOLITE MEASURED BY SINGLE PELLET DIFFUSION REACTOR

本文利用单粒子扩散反应器对甲烷在4A沸石中的扩散系数进行了测量。首先由沸石的吸附柱的一级矩得到吸附平衡常数Ka,即: △μ=μ_1~c-μ_1^(in)=x/u·(1-a)/aρ_pK_a然后由单粒子扩散反应器的一级矩得到甲烷在4A沸石中的大孔扩散系数,即: μ_1~'=L^2/(6D_a)[(ε_a+ε_i)+(1-ε_a)ρK_a利用以上结果及单粒子扩散反应器的二级矩则可得到甲烷在4A沸石中的微孔扩散系数,即: μ'_2=(L^4)[(ε_a+ε_i)+(1-ε_a)ρK_a]~2)/(90D^2_a+(L^2(ε_i+ρK_a)~2·γ_0~2)/(45D_a·D_i(1-ε_a))得到的实验条件下的微孔扩散系数在3.34×10^(-11)-3.90×10^(-11)cm^2/s范围内,扩散活化能为2.1kJ/mol。

Intracrystalline diffusivities (D_i) of methane in 4A zeolite were measured in a single pellet diffusion reactor,and the D_i is got from the second moment of the reactor:μ'_2=(L^4[(ε_a+ε_i)+(1-ε_a)pK_a]~2)/(90D_a^2)+(L^2(ε_i+pK_a)~2r_0~2)/(45D_aD_i(1-ε_a) where the adsorption equilibrium constant K_a is obtained from the first moment of the adsorption column of 4A zeolite: △μ=μ_1~c-μ_1^(in)=x/u (1-α)/αρK_a and the intercrystalline diffusivity D_a is gained from the first moment of the single pellet diffusion reactor: μ'_1=(L^2)/(6D_a)[(ε_a+ε_i)+(1-ε_a)ρK_a] Under the experimental conditions the intracrystalline diffusivities are in the range of 3.34×10^(-11)-3.90×10^(-11)cm^2/s and the activation energy for diffusion is 2.1kJ/mol.