Features of the Catalytic Cracking of Propane with a Step-Wise Change Pr[sub.x]Yb[sub.2−x]Zr[sub.2]O[sub.7]

• Published in: Catalysts 2023-02, Vol.13 (2)
• Main Authors: Markova, Ekaterina B, Cherednichenko, Alexander G, Smirnova, Sofia S, Sheshko, Tatiana F, Kryuchkova, Tatiana A
• Format: Article
• Language: English
• Subjects: Adsorption; Chromium; Propane
• ISSN: 2073-4344; 2073-4344
• DOI: 10.3390/catal13020396

In this paper, the features of catalytic cracking of propane with a step-wise change in the composition of the catalyst from Pr[sub.2]Zr[sub.2]O[sub.7] to Yb[sub.2]Zr[sub.2]O[sub.7] were considered. For the research, samples of catalysts Pr[sub.2]Zr[sub.2]O[sub.7], (Pr[sub.0.75]Yb[sub.0.25])[sub.2]Zr[sub.2]O[sub.7], (Pr[sub.0.5]Yb[sub.0.5])[sub.2]Zr[sub.2]O[sub.7], (Pr[sub.0.25]Yb[sub.0.75])[sub.2]Zr[sub.2]O[sub.7] and Yb[sub.2]Zr[sub.2]O[sub.7] were synthesized and analyzed. Analysis of the results from catalytic experiments showed that for the catalyst (Pr[sub.0.25]Yb[sub.0.75])[sub.2]Zr[sub.2]O[sub.7], at a temperature of 700 °C, the conversion of propane reaches values of 100%, but for Yb[sub.2]Zr[sub.2]O[sub.7], this indicator decreases to 84%. The selectivity for ethylene is consistently reduced from 85% to 28% in several catalysts (Pr[sub.0.75]Yb[sub.0.25])[sub.2]Zr[sub.2]O[sub.7] > Pr[sub.2]Zr[sub.2]O[sub.7] > (Pr[sub.0.5]Yb[sub.0.5])[sub.2]Zr[sub.2]O[sub.7] >(Pr[sub.0.25]Yb[sub.0.75])[sub.2]Zr[sub.2]O[sub.7] > Yb[sub.2]Zr[sub.2]O[sub.7]. An increase in the number of surface adsorption centers leads to a predominant rupture of the C-C bond in the propane molecule with the formation of ethylene. When ytterbium ions are introduced into the catalyst, the amount of ethylene in the reaction products decreases, but the selectivity for propylene increases in the series Pr[sub.2]Zr[sub.2]O[sub.7] < (Pr[sub.0.75]Yb[sub.0.25])[sub.2]Zr[sub.2]O[sub.7] < (Pr[sub.0.5]Yb[sub.0.5])[sub.2]Zr[sub.2]O[sub.7] < Yb[sub.2]Zr[sub.2]O[sub.7] < (Pr[sub.0.25]Yb[sub.0.75])[sub.2]Zr[sub.2]O[sub.7], which is associated with a decrease in the binding energy of carbon atoms in propane with the catalytic center during adsorption.