Kinetics of oxidation of β-picoline to nicotinic acid over vanadia-titania catalyst. 4. Kinetic model

Abstract

A kinetic model for the β-picoline oxidation over vanadia-titania catalyst is presented. The model covers the reaction mechanism, temperature dependences and a system of kinetic equations. The activation energies and constants in these equations are calculated.

Kinetics of the β-picoline oxidation to nicotinic acid over vanadia-titania catalyst. 2. Effect of dioxygen and β-picoline

“…The BET surface area was 25 m 2 /g. Similarly to [3], the catalyst was shaped as a ring of 4 mm in diameter, 5 mm in height, and with the walls being 1 mm thick.…”

“…The experimental procedure, chromatographic analysis of the components of the reaction mixture, and calculations are described elsewhere [3].…”

“…The prospect of the industrial implementation of this method makes it necessary to _________________________ develop a kinetic model applicable to the real-shaped pellets of the catalyst. The reaction network was revealed in previous studies, in which the rates of the partial reactions (β-picoline transformation into nicotinic acid, pyridine-3-carbaldehyde, pyridine-3-nitrile, pyridine and carbon oxides) and product selectivities were considered in dependence on the β-picoline conversion [2][3][4][5]. At temperatures ranging from 250 to 300°C, in the kinetic region (on catalyst grains of 0.25-0.50 mm), nicotinic acid is formed via intermediate oxidation of β-picoline to pyridine-3-carbaldehyde [2].…”

“…At temperatures ranging from 250 to 300°C, in the kinetic region (on catalyst grains of 0.25-0.50 mm), nicotinic acid is formed via intermediate oxidation of β-picoline to pyridine-3-carbaldehyde [2]. On a ring-shaped catalyst particle, the formation of nicotinic acid can be described with a parallel-consecutive scheme, via the intermediate pyridine-3-carbaldehyde and directly from β-picoline [3]. The parallel route is a pseudo-route caused by diffusion limitations [6].…”

“…The effect of water had been examined at its content in the reaction mixture ranging from 5 to 40% [3]. Water was found to accelerate the formation of pyridine-3-carbaldehyde and nicotinic acid, but does not affect their further oxidation and the deep oxidation of β-picoline.…”