Oxidative ammonolysis of 3- and 4-methylpyridines on vanadium oxide catalysts modified with titanium and tin oxides

Abstract

Catalytic properties of vanadium-titanium-tin oxides catalysts of various compositions were studied in oxidative ammonolysis of 3-and 4-methylpyridines.Heterogeneous catalytic oxidation by atmospheric oxygen is the main way for oxidative processing of petrochemical and coking hydrocarbon raw materials into oxygen-containing organic compounds. The reaction of oxidative ammonolysis is a catalytic reaction of hydrocarbons with atmospheric oxygen and ammonia belong to promising industrial methods for synthesis of valuable nitrogen-containing organic half-products and monomers [1].The reactions of oxidation and oxidative ammonolysis of alkyl aromatic compounds are purposively studied at Bekturov Institute of Chemical Sciences Joint-Stock Company. Particular attention is being given to development of catalysts determining the degree and selectivity of conversion of raw materials into appropriate target products. For example, the catalytic activity of a number of multicomponent vanadium oxide catalysts modifi ed with oxides of Group IV and VI metals in oxidative ammonolysis of 3-and 4-methylpyridines has been studied. Catalysts developed for this process on the basis of vanadium, tin, and titanium oxides are highly effi cient: the oxidative ammonolysis of methylpyridines occurs with high conversion of starting substances [2]. The optimal conditions, in which target products can be obtained in >90% yield, have been determined for synthesis of pyridinecarboxylic acid nitriles. It has been found that, to achieve a high selectivity of nitrile formation, the process of oxidative ammonolysis on V-Ti-Sn-O oxides catalysts should be performed with 5-10 mol of ammonia per mole of starting substances, which raises the ammonia concentration in effl uent gases and makes the process more technologically intricate. The excess of ammonia and high temperature occasionally lead to a spontaneous rise in temperature and enhance oxidative destruction processes, which diminishes the formation selectivity of the target products. In addition, these catalysts operate at high temperatures (360-400°C), the conversion of the starting substances being low at moderate temperatures. Therefore, a search for new active and selective catalysts capable of operating at lower temperatures at a minimum amount of ammonia was conducted.It is known [3] that ammonia can be oxidized by several pathways, and the nature of a catalyst and the process conditions (temperature, composition of the ammonia-air mixture, contact duration, and other factors) affect the degree and selectivity of ammonia conversion. Previously, the composition of ammonia oxidation products formed on vanadium oxide catalysts modifi ed with titanium and tin oxides have been studied and it was found that ammonia is oxidized on the catalysts under study to give N 2 , N 2 O, and NO 2 . It was shown that, selecting the molar ratio between oxygen

Oxidative Ammonolysis of 4-Methylpyridine on Oxide Vanadium-Titanium-Zirconium Catalyst Modified by Tin and Tungsten Oxides

“…Currently, binary and multicomponent vanadium oxide systems [5], which contain additives of metal oxides [6] having a modifying effect on the properties of oxide catalysts,are usedfor the oxidative ammonolysis of 4-methylpyridine.Titanium and tin dioxides are used as a component of many catalysts for the oxidation and oxidative ammonolysis of organic compounds. A. Martin, B. Lücke [7] presented a review of the current state in vapor-phase oxidation, ammoxidation of substituted methyl aromatic, and heteroaromatic hydrocarbons using V-containing catalysts.Earlier mixed vanadium-titanium-tin catalysts effective in the oxidative ammonolysis of 4-methylpyridine were developed in the Bekturov Institute of Chemical Sciences [8]. These catalysts showed high catalytic activity in the reaction of oxidative ammonolysis of methylpyridines [9], making it possible to obtain nitriles of pyridine carboxylic acids with a selectivity of 90-95%.…”