The mechanism of catalyst deactivation and by-product formation in acetone ammoximation catalyzed by hollow titanium silicalite

• Acetone ammoximation was catalyzed by hollow titanium silicalite using water as solvent.
• For the first time, deactivation mechanism of HTS in acetone ammoximation was studied.
• Amines, formed by autocatalytic reaction, adsorbed on the active sites of catalyst.
• Micropores was blocked mainly by DMNB, formed by oxidative coupling.
• For the first time, polynitro-compound was found in ketone ammoximation.

The deactivation mechanism of hollow titanium silicalite (HTS) in aqueous ammoximation of acetone was investigated. Amines and polynitro-compounds, formed by alkaline autocatalytic and oxidative coupling reaction respectively, were determined to be the main by-products. The results showed that deactivation of HTS could be caused by two main reasons: (1) slow deactivation due to by-product amines adsorbed on the active sites of catalyst surface; (2) rapid deactivation in the late period due to by-products, mainly 2,3-dimethyl-2,3-dinitrobutane (DMNB), filling and blocking the pores of catalyst.

Amines absorbed on the active sites and pore blocking by by-products mainly polynitro-compound DMNB were two main reasons causing HTS catalyst deactivation in the reaction of acetone ammoxidation when using water as solvent.Figure optionsDownload high-quality image (149 K)Download as PowerPoint slide