Selective C-and O-methylation of catechol in gas phase over modified g-alumina

Gas phase methylation of catechol by methanol over modified gamma-alumina catalysts is studied experimentally. The catalyst composition and the reaction conditions are optimized to attain the highest selectivity towards 3-methylcatechol (C-methylation) or guaiacol (O-methylation and to diminish the catalyst deactivation. The modified gamma-alumina {Li+ 3 % Mg2+ 5 %/gamma-Al2O3} was found to be the best with respect to the 3-methylcatechol formation. At 350 degrees C and at a conversion level of 28% the selectivity of 92% towards 3-methylcatehcol was reached. The deactivation was observed to be lower if compared to pure gamma-alumina. Selectivity towards guaiacol formation increased with surface acidity and reached 89% over phosphated gamma-alumina at 270 degrees C. The catalyst structure was determined with a high confidence factor via "full-profile X-ray analysis". The experimental data relating to activity/selectivity as well as catalyst stability to coke formation were explained from the model found for the catalyst structure.


Published in:
Science and Technology in Catalysis 1998, 159-164
Year:
1999
Publisher:
Amsterdam, Elsevier
Keywords:
Note:
CAN 132:224053 45-4 Industrial Organic Chemicals, Leather, Fats, and Waxes Institute of Chemical Engineering,Swiss Federal Institute of Technology,Lausanne,Switz. Journal 0167-2991 written in English. 90-05-1P (Guaiacol); 488-17-5P (3-Methylcatechol) Role: IMF (Industrial manufacture), PREP (Preparation) (prepn. by methylation of catechol with MeOH over modified alumina catalysts); 7439-93-2 (Lithium); 7439-95-4 (Magnesium) Role: CAT (Catalyst use), USES (Uses) (selective C-and O-methylation of catechol with MeOH over alumina catalysts contg.); 1344-28-1 (Alumina); 1344-28-1D (Alumina) Role: CAT (Catalyst use), USES (Uses) (selective C-and O-methylation of catechol with MeOH over modified alumina catalysts); 67-56-1 (Methanol); 120-80-9 (Catechol) Role: RCT (Reactant), RACT (Reactant or reagent) (selective C-and O-methylation of catechol with MeOH over modified alumina catalysts)
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