Análisis de Variables de Regeneración y Rejuvenecimiento de

V. A. MAZZIERI; C. L. PIECK; C. R. VERA; J. C. YORI; J. M. GRAU

Gramado, Rio Grande do Sul, Brasil

Simposio; XX SICAT – Simpósio Ibero-Americano de Catálise; 2006

Sociedad Brasilera de Catalisis

En este trabajo se estudia la desactivación y sinterización de la función metálica de catalizadores PtReSn/Al2O3-Cl y PtReGe/ Al2O3-Cl y se analiza la regeneración, mediante quemado del coque a distintas temperaturas, 400-500ºC y tiempos, 0,5; 2; 6 y 12 h de quemado y el rejuvenecimiento por oxicloración, analizándose el efecto de la concentración de cloro (300; 530 y 900 ppm) y el tratamiento posterior a 520 ºC. El análisis del coque y del estado final de la fase metálica se realiza mediante oxidación y reducción a temperatura programada (TPO y TPR). La desactivación o grado de recuperación de la actividad metálica se mide mediante la reacción de deshidrogenación de ciclohexano. Se ha encontrado que los catalizadores PtReSn son más estables que los de PtReGe debido a la menor deposición de coque obtenida. Se necesita más de 6 h para eliminar coque a 400 °C mientras que a 500 °C se logra en 30 min. La regeneración conduce a una segregación de las fases metálicas. La sinterización a 650 °C modifica severamente la fase metálica, produciendo segregación del Pt de los otros componentes. Los tratamientos de rejuvenecimiento (Cl/aire, alta T) no logran restituir la fase inicial. .The deactivation, sintering and regeneration of the metal function of PtReSn/Al2O3-Cl and PtReGe/Al2O3-Cl were studied in this work. The variables affecting the rejuvenation of the metal function (oxychlorination at 480 °C with 300, 530 and 900 ppm, stabilization at 520 °C) and the coke burning-off (400-500 °C, 0.5, 2, 6 or 12 h) were assessed. The analysis of the carbon deposits and the final state of the metal function is performed y means of oxidation and reduction at temperature programmed reduction (TPO and TPR). The deactivation or degree of recovery of the metalo function is assessed with the cyclohexane dehydrogenation reaction. It is found that the PtReSn catalysts are more stable than the PtReGe ones due to the lower amount of coke deposited. More than 6 h are needed to eliminate the coke at 400 °C while at 500 °C the coke is eliminated in 30 min. Regeneration produces a segregation of the metal phases. Metal particle sintering at 650 °C modifies the metal function severely, producing the segregation of Pt from the other components of the metal unction. Any of the rejuvenation treatments (Cl, air, high temperature) is unable to restore the original state of the metal function. .The deactivation, sintering and regeneration of the metal function of PtReSn/Al2O3-Cl and PtReGe/Al2O3-Cl were studied in this work. The variables affecting the rejuvenation of the metal function (oxychlorination at 480 °C with 300, 530 and 900 ppm, stabilization at 520 °C) and the coke burning-off (400-500 °C, 0.5, 2, 6 or 12 h) were assessed. The analysis of the carbon deposits and the final state of the metal function is performed y means of oxidation and reduction at temperature programmed reduction (TPO and TPR). The deactivation or degree of recovery of the metalo function is assessed with the cyclohexane dehydrogenation reaction. It is found that the PtReSn catalysts are more stable than the PtReGe ones due to the lower amount of coke deposited. More than 6 h are needed to eliminate the coke at 400 °C while at 500 °C the coke is eliminated in 30 min. Regeneration produces a segregation of the metal phases. Metal particle sintering at 650 °C modifies the metal function severely, producing the segregation of Pt from the other components of the metal unction. Any of the rejuvenation treatments (Cl, air, high temperature) is unable to restore the original state of the metal function. 2O3-Cl y PtReGe/ Al2O3-Cl y se analiza la regeneración, mediante quemado del coque a distintas temperaturas, 400-500ºC y tiempos, 0,5; 2; 6 y 12 h de quemado y el rejuvenecimiento por oxicloración, analizándose el efecto de la concentración de cloro (300; 530 y 900 ppm) y el tratamiento posterior a 520 ºC. El análisis del coque y del estado final de la fase metálica se realiza mediante oxidación y reducción a temperatura programada (TPO y TPR). La desactivación o grado de recuperación de la actividad metálica se mide mediante la reacción de deshidrogenación de ciclohexano. Se ha encontrado que los catalizadores PtReSn son más estables que los de PtReGe debido a la menor deposición de coque obtenida. Se necesita más de 6 h para eliminar coque a 400 °C mientras que a 500 °C se logra en 30 min. La regeneración conduce a una segregación de las fases metálicas. La sinterización a 650 °C modifica severamente la fase metálica, produciendo segregación del Pt de los otros componentes. Los tratamientos de rejuvenecimiento (Cl/aire, alta T) no logran restituir la fase inicial. .The deactivation, sintering and regeneration of the metal function of PtReSn/Al2O3-Cl and PtReGe/Al2O3-Cl were studied in this work. The variables affecting the rejuvenation of the metal function (oxychlorination at 480 °C with 300, 530 and 900 ppm, stabilization at 520 °C) and the coke burning-off (400-500 °C, 0.5, 2, 6 or 12 h) were assessed. The analysis of the carbon deposits and the final state of the metal function is performed y means of oxidation and reduction at temperature programmed reduction (TPO and TPR). The deactivation or degree of recovery of the metalo function is assessed with the cyclohexane dehydrogenation reaction. It is found that the PtReSn catalysts are more stable than the PtReGe ones due to the lower amount of coke deposited. More than 6 h are needed to eliminate the coke at 400 °C while at 500 °C the coke is eliminated in 30 min. Regeneration produces a segregation of the metal phases. Metal particle sintering at 650 °C modifies the metal function severely, producing the segregation of Pt from the other components of the metal unction. Any of the rejuvenation treatments (Cl, air, high temperature) is unable to restore the original state of the metal function.2O3-Cl and PtReGe/Al2O3-Cl were studied in this work. The variables affecting the rejuvenation of the metal function (oxychlorination at 480 °C with 300, 530 and 900 ppm, stabilization at 520 °C) and the coke burning-off (400-500 °C, 0.5, 2, 6 or 12 h) were assessed. The analysis of the carbon deposits and the final state of the metal function is performed y means of oxidation and reduction at temperature programmed reduction (TPO and TPR). The deactivation or degree of recovery of the metalo function is assessed with the cyclohexane dehydrogenation reaction. It is found that the PtReSn catalysts are more stable than the PtReGe ones due to the lower amount of coke deposited. More than 6 h are needed to eliminate the coke at 400 °C while at 500 °C the coke is eliminated in 30 min. Regeneration produces a segregation of the metal phases. Metal particle sintering at 650 °C modifies the metal function severely, producing the segregation of Pt from the other components of the metal unction. Any of the rejuvenation treatments (Cl, air, high temperature) is unable to restore the original state of the metal function.