In Ukrainian

Abstract

Propylene is important olefin with an annual production of roughly 8×10 7 t. A great deal of attention has been paid to the on-purpose propylene production technology, such as propane dehydrogenation in the presence of mild oxidants (CO 2 , N 2 O), due to its potential to make-up the shortfall of propylene supply left by conventional steam cracking of hydrocarbons where propylene is produced as a byproduct of ethylene. The In 2 O 3 –Al 2 O 3 is one of the most effective catalysts for propylene production via oxidative dehydrogenation of propane with CO 2 (PODH-CO 2 ). The textural characteristics of alumina-based compositions depend on their preparation method [Journal of Structural Chemistry. 2011. 52 : 326]. The work presents results on the effect of the preparation method of In 2 O 3 -Al 2 O 3 (YSZ) compositions on their textural and structural characteristics, and hence catalytic performance in the PODH-CO 2 . The catalysts were prepared by the methods of alcoholic coprecipitation of In and Al hydroxides from nitrates of these elements, alcoholic coprecipitation with the following hydrothermal treatment (HT), dry mixing and grinding of In and Al nitrates, impregnation of the supports (commercial Al 2 O 3 and Y-stabilized zirconia (YSZ)) with an aqueous solution of indium nitrate. Catalysts were characterized using the powder X-ray diffraction (Bruker AXS Advance) and nitrogen adsorption-desorption at liquid nitrogen temperature (Sorptomatic 1990 porous material analyzer). Catalysts tests in the PODH-CO 2 were performed in fixed-bed flow reactor at atmospheric pressure, temperature of 600 °C and GHSV = 6000 h –1 . During reaction, the gas reactant contained (vol. %) 2.5 C 3 H 8 , 5–15 CO 2 and a balance of He. The feed and the reaction products were analyzed using on-line GC equipped with the TCD as well as Poropak Q and molecular sieves columns. The catalysts performance in the PODH – CO 2 was characterized by the propane conversion, propylene selectivity and yield, rates of propane conversion and propylene formation normalized per catalyst weight (r С3Н8 (С3Н6) , mmol С 3 Н 8 (С 3 Н 6 )·h –1· g –1 ). In the presence of In 2 O 3 -Al 2 O 3 catalysts the highest selectivity to propylene and propylene yield are achieved for PODH-CO 2 reaction mixture with 10 vol. % CO 2 . The hydrothermal treatment of catalyst In 2 O 3 -Al 2 O 3 (HT) improves its mesoporous structure (specific surface and mesoporous volume), that results in higher selectivity to propylene (51 %) compared to catalysts prepared by other methods (25–36 %). The highest propane conversion and propylene yield are achieved on In 2 O 3 -YSZ catalyst, indicating that the effect of the support nature. In the presence of the developed catalysts In 2 O 3 -Al 2 O 3 (YSZ), a higher propane conversion rate (1.31–2.3 mmol С 3 H 8 ·h –1 ·g –1 ) and a slightly lower rate of propylene formation (0.74 mmol С 3 H 6 ·h –1 ·g –1 ) compared with the catalysts of similar composition In 2 O 3 -Al 2 O 3 (r С3H8 = 1.21 mmol С 3 H 8 ·h –1 ·g –1 , r С3H6 = 0.93 mmol С 3 H 6 ·h –1 ·g –1 ) [Journal of Catalysis. 2010. 272 : 101] are achieved. Thus, the catalytic performance of In 2 O 3 -Al 2 O 3 (YSZ) compositions in the PODH-CO 2 depends on both the support nature and their porous structure, which can be optimized by their preparation method.