Catalytic Properties and Deactivation Behavior of Crystalline Microporous MAPO-36

Abstract

MAPO-36 showed high catalytic activity in conversion reactions of alcohols, linear, branched, and cycloalkanes, and aromatics. In ethanol, n-hexane, cyclohexane, and isooctane conversion reactions, MAPO-36 showed significantly higher conversion and concentration of aromatics than MAPO-5, SAPO-5, and AIPO 4-5. The distribution of aliphatics and aromatics is different in these reactions over MAPO-36, MAPO-5, SAPO-5, AIPO 4-5, and H-ZSM-5. MAPO-36 exhibited lower n-hexane conversion than H-ZSM-5; however, the aromatics yield was higher. The trend was reversed in the cyclohexane conversion reaction. The toluene disproportionation and o-xylene conversion activity of MAPO-36 is very high as compared to MAPO-5, SAPO-5, AIPO 4-5, and HZSM-5. In the o-xylene conversion reaction, MAPO-36 exhibited higher xylene loss, indicating that the disproportionation is more pronounced than the isomerization. The effect of pyridine poisoned strong acid sites on the catalytic properties of the catalysts was studied. The influence of pulse number on the catalytic activity of MAPO-36 in n-pentane, n-hexane, 3-methylpentane, cyclohexane, methanol, and toluene reactions was investigated. The deactivation of MAPO-36 is lowest as compared to MAPO-5, SAPO-5, and AIPO 4-5 in the ethylbenzene conversion reaction. The results on the dependence of cumene cracking activity of MAPO-36, SAPO-5, and AIPO 4-5 on tine-on-stream show that the initial activity of MAPO-36 is high, though it decreases faster than that of SAPO-5 and AIPO 4-5. In situ IR techniques were used to investigate coke formation and temperature programmed oxidation of coke deposited during the cumene cracking reaction over MAPO-36.