Publication

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

Albert Renken, Lioubov Kiwi
1999
Book Chapters

Abstract

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.

Official source

https://infoscience.epfl.ch/entities/publication/c85219a3-26ce-43ce-a326-72837ec2634f

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Albert Renken, Lioubov Kiwi
1999
Book Chapters

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/c85219a3-26ce-43ce-a326-72837ec2634f

About this result

Related concepts (32)

Heterogeneous catalysis

Heterogeneous catalysis is catalysis where the phase of catalysts differs from that of the reactants or products. The process contrasts with homogeneous catalysis where the reactants, products and catalyst exist in the same phase. Phase distinguishes between not only solid, liquid, and gas components, but also immiscible mixtures (e.g. oil and water), or anywhere an interface is present. Heterogeneous catalysis typically involves solid phase catalysts and gas phase reactants.

Catalyst poisoning

Catalyst poisoning is the partial or total deactivation of a catalyst by a chemical compound. Poisoning refers specifically to chemical deactivation, rather than other mechanisms of catalyst degradation such as thermal decomposition or physical damage. Although usually undesirable, poisoning may be helpful when it results in improved catalyst selectivity (e.g. Lindlar's catalyst). An important historic example was the poisoning of catalytic converters by leaded fuel.

Methylation

In the chemical sciences, methylation denotes the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These terms are commonly used in chemistry, biochemistry, soil science, and the biological sciences. In biological systems, methylation is catalyzed by enzymes; such methylation can be involved in modification of heavy metals, regulation of gene expression, regulation of protein function, and RNA processing.

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

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