Abstract: Adsorption and diffusion behavior of C4 fractions (n-butane and butene-1) on special shape-selective and acidic ZSM-5 zeolite with different Si/Al ratios, which is used as catalyst in olefins catalytic cracking (OCC) technology, was investigated using an intelligent gravimetric analysis apparatus (IGA-003, HIDEN) at 275, 288 and 300 K. The double Langmuir model was applied to simulate the adsorption of n-butane and butene-1 on ZSM-5 zeolite samples. The diffusion coefficients of n-butane and butene-1 were correlated in terms of the Fick diffusion model. The results indicate that the diffusion of n-butane and butene-1on ZSM-5 zeolites are intracrystalline diffusion, and the diffusion coefficients are of the order of magnitude 10-14 m2/s. In addition, the diffusion coefficients of n-butane are larger than those of butene-1 on ZSM-5 zeolites at the same temperature and pressure. Moreover, the diffusion coefficients of n-butane and butene-1 on ZSM-5 zeolites all increase with temperature, and increase with pressure first and decrease at high pressure. In addition, the diffusion coefficients of n-butane all increase with the Si/Al ratio. The results are applicable in the C4 olefins catalytic cracking technology.

Key words: n-butane, butene-1, ZSM-5 zeolite, Si/Al ratio, adsorption isotherm, diffusion coefficient

摘要： 以应用于烯烃催化裂解工艺中的具有独特择形性和酸性的ZSM-5分子筛为研究对象，采用重力分析仪在275, 288及300 K下对碳四烃(以正丁烷和丁烯-1为代表)在不同硅/铝比ZSM-5分子筛内的吸附和扩散行为进行了研究. 建立了正丁烷和丁烯-1在ZSM-5分子筛上的双朗格缪尔吸附模型. 同时，运用Fick扩散模型关联得到了正丁烷及丁烯-1在ZSM-5分子筛内的扩散系数. 结果表明，正丁烷及丁烯-1在ZSM-5分子筛内的扩散属于晶体扩散，二者的扩散系数在10-14 m2/s数量级，正丁烷的扩散速率大于丁烯-1. 正丁烷与丁烯-1在ZSM-5分子筛内的扩散速率均随温度的增加而增加，随着体系平衡压力的增加先增加后减小，而且二者的扩散系数随样品硅/铝比的增加而增加. 研究结果为碳四烃催化裂解工艺提供了相关的基础工程数据.

关键词: 正丁烷, 丁烯-1, ZSM-5分子筛, 硅/铝比, 吸附等温线, 扩散系数