Известия Томского политехнического университета: Инжиниринг георесурсов (May 2019)
Nickel-containing systems in hydrocarbon partial oxidation
Abstract
The study of the nickel-containing systems obtained in various ways in hydrocarbon partial oxidation to synthesis gas is perspective for technology of catalysts. The main aim of the study: synthesis and comparison of nickel-containing block catalysts obtained by self-propagating high-temperature synthesis with the granulated catalytic systems. Key parameters are the size of crystallites of an active component and catalyst productivity on synthesis gas. The methods used in the study: chromatography, determination of specific surface area by low-temperature nitrogen adsorption method, scanning electron microscopy, element analysis, X-ray phase analysis. The results: Nickel dispersion providing total catalytically active metal surface is of great importance for natural gas partial catalytic oxidation to obtain high yields of target products and synthesis gas productivity. For block catalysts obtained by self-propagating high-temperature synthesis the influence of reactionary environment at high temperatures within 20-25 hours promotes the increase in the total area of Ni active component. That allows achieving synthesis gas productivity of 7,1-103 cm3 (synthesis gas)/cm3 (catalyst)⋅h. For the catalytic systems obtained by precipitation, it is shown that oxide phase chemical composition influences metal nickel particle size. For the granulated catalysts obtained by precipitation after the 25 hour operation, particle average size (on area of coherent dispersion) of metal nickel is 3-4,5 times less than Ni sizes in the catalysts obtained by self-propagating high-temperature synthesis. It allows achieving synthesis gas productivity of 8,1-103 cm3 /cm3 -h decreasing average temperature on a catalyst layer by ~ 100 °C in comparison with the blocks obtained by self-propagating high-temperature synthesis.
