Coking and deactivation of boron modified Al-MCM-41 for vapor-phase Beckmann rearrangement reaction

The influences of different parameters such as boron content, reaction temperature, and calcined temperature on carbonaceous compounds deposited on the boron modified Al-MCM-41 catalyst have been investigated. The carbonaceous compounds were characterized using FT-IR, N2 adsorption, TGA, SEM, XPS, NH3-TPD, and a solvent extraction analysis. The coke deposited on the catalyst was majorly amorphous. The filamentous carbon and graphitic-like carbon were not formed on the catalyst during the vapor-phase Beckmann rearrangement over boron modified Al-MCM-41 catalyst. The coke was preferably deposited on the acid sites. Neither the high nor the low reaction temperate was beneficial to decrease the amount of coke. The uniform dispersion of boron in the catalyst was good at reducing the formation of coke. The catalyst deactivation was attributed to blockade of the pore and active sites by the excessive dehydrogenated carbon species, except the aliphatic carbon (B.E. = 284.6 eV).

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► The coke deposited on boron-Al MCM-48 during vapor-phase Beckmann rearrangement was of amorphous structure.
► The uniform dispersion of boron in the catalyst was good at reducing the formation of coke.
► Catalyst deactivation was attributed to blockade of active sites by dehydrogenated carbon species.
► Dehydrogenated carbon species, rather than aliphatic carbon, was the main reason for catalyst deactivation.