PHASE COMPOSITION, MAGNETIC AND CATALYTIC PROPERTIES OF NANOSTRUCTURED NICKEL-CONTAINING NAX ZEOLITE IN THE REACTION OF OXIDATIVE CONVERSION OF PROPANOL-1
Nickel - containing (1-10 wt.%) Catalysts based on NaX zeolite in the reaction of 1 - propanol oxidative conversion have been investigated. The phase composition and magnetic properties of these systems before and after the reaction have been characterized by the methods of X - ray phase analysis (XPA) and electronic magnetic resonance (EMR). The dependence of the catalytic properties on the nickel content in the catalysts and the reaction temperature has been established. It was shown that the main gas - phase products of this reaction are propylene C3H6, propenal (acrolein) C3H4O, propanal C3H6O, and carbon dioxide CO2. At reaction temperatures up to 623K, propylene is formed from the target products, and at temperatures above 623K, propanal and propenal are formed. It is assumed that the latter are formed as a result of the oxidation and oxidative dehydrogenation of propylene formed at the initial stage of the conversion of propanol - 1. It was shown that among the studied catalysts, the highest propanal yield was observed for samples containing 5 wt% nickel, and the highest propenal yield was observed for a 10 wt% Ni / NaX sample. With the conversion of propanol - 1 on NiNaX catalysts, propene can be obtained with a yield of 22.3% with an alcohol conversion of 65.4% at a temperature of 623K. At the same time, at temperatures above 623K, propanol - 1 is dehydrogenated into propanal, and propenal is also formed. It was found that the zeolite matrix provides the formation of highly dispersed nickel oxide during the decomposition of deposited nickel nitrate. The average size of the resulting NiO particles does not exceed 30 nm, which is noticeably smaller than that of NiO particles formed during the decomposition of individual nickel nitrate. The EMR spectroscopy data show that the nickel oxide stabilized in the zeolite structure is superpara/ferromagnetic. It is assumed that the active phase in the obtained systems are nanostructured NiO particles with active oxygen. The mechanism of the reaction with the participation of NiO particles and the possibilities of X - ray diffractometry and EMR spectroscopy as methods for controlling the size - dependent catalytic properties of nickel - containing zeolite systems are discussed.