MOR/SBA-15 Composite Catalysts with Interconnected Meso/Micropores for Improved Activity and Stability in Isopropylation of Naphthalene

Abstract

The isopropylation of naphthalene with isopropyl alcohol was studied over composites of MOR/SBA-15 in a high-pressure, fixed-bed reactor. The MOR catalyst showed a high 2,6-/2,7-diisopropyl naphthalene (DIPN) ratio of 1.75, but a low naphthalene conversion (54%) and fast deactivation of the catalyst. The composites of MOR/SBA-15 were prepared by a hydrothermal recrystallization process to obtain hierarchical micro/mesopores. During the process, MOR recrystallized in the mesopores of SBA-15, the structure of which was stabilized by carbon coating formed on the pore walls as a template. The best prepared MOR/SBA-15 catalyst achieved a high conversion of 85%, high stability, and less coking, while maintaining the high 2,6-/2,7-DIPN ratio (≈1.8). The modified micro/mesopore structure allowed facile diffusion of bulky molecules to and from active catalytic sites located in the small MOR pores as a result of the connection between the two types of pores in the MOR/SBA-15 composite. Networking of big and small: To improve naphthalene conversion in isopropylation of naphthalene, a hierarchical meso/micropore structure of zeolite composites is achieved by combining micropores of MOR with mesopores of SBA-15. In the hydrothermal recrystallization process, MOR recrystallizes in the mesopores of SBA-15 stabilized by carbon coating formed on the pore walls as a template. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.