分子筛类型对正戊烷催化裂解反应性能的影响

为了解决石脑油中正戊烷难以高效催化裂解为低碳烯烃的问题，先采用Aspen Plus模拟软件对正戊烷的催化裂解反应进行热力学平衡分析，然后考察分子筛类型对正戊烷催化裂解的低碳烯烃收率和选择性的影响规律。对正戊烷的催化裂解反应进行热力学分析的结果表明，当反应温度高于650 ℃时，丙烯和乙烯的质量比m(C₃H₆)/m(C₂H₄)<1，且低碳烯烃(C₂H₄+C₃H₆+C₄H₈)的收率开始增速缓慢。因此，综合考虑m(C₃H₆)/m(C₂H₄)和低碳烯烃收率，选择在反应温度650 ℃下考察正戊烷在不同类型分子筛上的催化裂解反应性能。结果表明：在MTT分子筛上催化裂解的低碳烯烃选择性较高，在温度为650 ℃、压力为0.1MPa、MHSV为540 h^-1的反应条件下，正戊烷在MTT分子筛上催化裂解的低碳烯烃(C₂H₄+C₃H₆+C₄H₈)选择性为55.21%。通过对催化裂解过程的裂解和氢转移反应的分析，表明小孔径的MTT分子筛能够抑制双分子反应，包括双分子裂解反应和双分子氢转移反应，从而提高低碳烯烃的选择性。

Effect of Zeolite Types on the Performance of n-Pentane Catalytic Cracking Reaction

To solve the problem that is difficult to achieve efficient catalytic cracking of n-pentane in naphtha into light olefins, the thermodynamic equilibrium of n-pentane catalytic cracking was analyzed by Aspen Plus simulation software, and then the influence law of zeolite types on the yield and selectivity of light olefins in n-pentane catalytic cracking was investigated. The thermodynamic analysis results of the catalytic thermal cracking of n-pentane show that when the reaction temperature is higher than 650 ℃, the mass ratio of propene to ethylene (m(C₃H₆)/m(C₂H₄)) is smaller than 1, and the yield of light olefins (C₂H₄+C₃H₆+C₄H₈) is increasing slowly. Therefore, considering （m(C₃H₆)/m(C₂H₄)）and the yield of light olefins, the catalytic cracking performance of n-pentane on different types of zeolites was investigated at 650 ℃. The results show that the selectivity of light olefins catalyzed and cracked on MTT zeolite is higher. Under the reaction conditions of temperature 650 ℃, pressure 0.1 MPa and MHSV 540 h^-1, the selectivity of light olefins (C₂H₄+C₃H₆+C₄H₈)catalyzed and cracked by n-pentane on MTT zeolite is 55.21%. Combined with the analysis of the cracking reaction and hydrogen transfer reaction in the catalytic cracking process, the results indicate that MTT zeolite of small pore size can inhibit the bimolecular reaction, including bimolecular cracking reaction and bimolecular hydrogen transfer reaction, so as to improve the selectivity of light olefins.