Study on the deactivation and regeneration mechanism of Cu-Al catalyst in the hydrogenation of diethyl oxalate

The hydrotreating of dialkyl oxalate to ethylene glycol process as a representative technology pathway for the efficient and clean utilization of coal has gained wide attention in the context of carbon neutrality. The deactivation mechanism and catalyst regeneration mechanism of the hydrotreating process pathway of diethyl oxalate were systematically investigated by experimental techniques and kinetic simulations using a Cu-Al catalyst as a model catalyst in the hydrogenation reaction with diethyl oxalate as a probe molecule, and a reliable deactivation mechanism was obtained. The weaving properties of the fresh and used catalyst samples were systematically investigated by XRD, TEM, GC-MASS, BET, and O2-TPO. Characterization data indicate that the catalyst deactivation was not caused by an increase in the size of the Cu nanoparticles and a change in the physical structure of the catalyst. The deactivation was triggered by the polymer molecules produced by dehydration, polycondensation and aromatization of ethyl glycolate molecules in the acidic sites, which covered the active sites and blocked the catalyst pores. The regeneration behavior under different atmospheres showed that regeneration under H2 atmosphere is unable to restore the reaction performance of the deactivated catalyst to the original level, while the activity of the regenerated catalyst under air atmosphere significantly exceeds that of the fresh catalyst.