Improvements in the Beckmann rearrangement process by using highly selective mesoporous catalysts.

ELIANA G. VASCHETTO; CASUSCELLI SANDRA; GRISELDA EIMER

MICROPOROUS AND MESOPOROUS MATERIALS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015 p. 175 - 181

1387-1811

The Beckmann rearrangement of cyclohexanone oxime (CHO) intoe-Caprolactam (e-C) at 300e380 °C and W/F= 1e60 gh/mol over a Al-MCM-41catalyst was studied in a flow reactor at atmospheric pressure. Differentreaction conditions as well as the nature of the solvents employed in the feedwere evaluated. The e-C was the main product on the whole reaction conditions,but temperatures above 360 °C favored its decomposition. A reaction pathway wasproposed in order to explain the results obtained at 360 °C. The stability andthe possibility of recycling of the catalyst were checked by XRD, N2 adsorption,FTIR, pyridine adsorption coupled with FTIR and catalytic activity tests. Thus,the catalyst could be used during 3600 min and then recovered and reused threetimes without significant changes in the active species, catalytic activity ande-C yield. In addition, a modification in the operating conditions, which consisted in pretreating the catalyst with 1-hexanol, allowed toimprove the yield to caprolactam by blocking the terminal silanols responsibleof the byproduct formation. Thus, the better catalytic performance was observedat 350 °C and W/F= 40 gh/mol, immediately after a catalyst pretreatment with1-hexanol during 3 h with 1-hexanol, which was also used as reaction solvent.Such conditions allowed us to achieve a high CHO conversion (95%) with a e-Cselectivity of around 100%, improving thus results previously reported.