Deactivation and regeneration of ethylenimine production catalyst

Understanding the Catalytic Stability of Cs2O–P2O5 over Acid-Activated Montmorillonite for the Gas-Phase Dehydration of Monoethanolamine to Ethylenimine

“…This may originate from the phase transition and/or leaching of Cs 4 P 2 O 7 during the catalytic process. As revealed in the previous literature, the sintering and/or loss of phosphorus species are main reasons for the deactivation over the silica-alkaline-phosphate catalyst. In our case, there are no extra XRD diffractions of either Cs- or P-containing species over the spent catalysts.…”

“…5,7,8,16 The earlier work reveals that coke deposition dominates the deactivation of SiO 2 -X m -P n -O p catalysts (X stands for alkali and alkaline-earth metals), which can be regenerated after burning the deposited coke at high temperatures. 5 However, in the later work from the same research group, 16 the deactivation of the Si 5 Cs 1 P 0.8 O x catalyst can be divided into two stages with different deactivation mechanisms, i.e., coking at the early stage of the reaction while structural changes of the catalyst including loss of phosphorus and sintering for the long-term catalyst deactivation. Noteworthy, this conclusion is drawn based on the reaction results with a relatively lower MEA conversion of about 45% although the catalyst is operated for a time on stream (TOS) as long as of 4000 h. 16 Under mild reaction conditions, i.e., 40 mL of the catalyst loaded in the reactor with flow rates of the N 2 diluent (1200 mL/min) and the MEA liquid (0.1 mL/min), coking is also considered to be the main reason for the deactivation of the (Cs 2 O) 5.5 -(P 2 O 5 ) 1.8 /SiO 2 catalyst since the online air-flow treatment of the deactivated catalyst at a slightly higher temperature of 450 °C for 5 h can fully restore both the MEA conversion and EI selectivity.…”

“…To date, there are only four open reports on the deactivation/regeneration of solid acids/bases for the MTE reaction. ,,, The earlier work reveals that coke deposition dominates the deactivation of SiO 2 -X m -P n -O p catalysts (X stands for alkali and alkaline-earth metals), which can be regenerated after burning the deposited coke at high temperatures . However, in the later work from the same research group, the deactivation of the Si 5 Cs 1 P 0.8 O x catalyst can be divided into two stages with different deactivation mechanisms, i.e., coking at the early stage of the reaction while structural changes of the catalyst including loss of phosphorus and sintering for the long-term catalyst deactivation. Noteworthy, this conclusion is drawn based on the reaction results with a relatively lower MEA conversion of about 45% although the catalyst is operated for a time on stream (TOS) as long as of 4000 h .…”