OP-II-3

OP-I-9A REDOX KINETICS FOR THE PARTIAL OXIDATION OF O-XYLENEON V 2 O 5 /TIO 2 CATALYSTSLópez-Isunza F.Departamento de Ingeniería de Procesos e Hidráulica, Universidad AutónomaMetropolitana-Iztapalapa. Av. San Rafael Atlixco 186, México 09340, D.F.felipe@xanum.uam.mxThe redox mechanism proposed by Mars & van Krevelen [1] has been used todescribe the kinetics for the partial oxidation of some hidrocarbons on mixed-oxidecatalysts. It has been shown that this mechanism reveals some inconsistencies [2],however they may disapear if one considers that in most of the intermediary steps ofthe partial oxidation, not one but two adjacent “oxidised” sites [3] participate, contraryto previous reports [1, 4-6]. In this work a kinetic model based on the redoxmechanism is developed based on the ideas of previous works [3, 4], and the kineticparameters obtained by simulations using a transient CSTR model are tunned topredict some observations from the partial oxidation of o-xylene in an industrial-scalefixed bed catalytic reactor [7] and from preliminary temperature data from a CSTR(Berty) system.The proposed kinetics is as follows:(1) A + 2θo ⇒ B + H 2 O + 2θr(2) B + θo ⇒ C + θr(3) C + 2θo ⇒ D + H 2 O + 2θr(4) D + 2θo ⇒ E + H 2 O + 2θr(5) E + 2θo ⇒ F + H 2 O + CO + 2θx(6) A + 2θo + 8 O 2 ⇒ 3CO + 4CO 2 + 5H 2 O + 2θx(7) E + 2θo + 7 O 2 ⇒ 2CO + 5CO 2 + 2H 2 O + 2θx(8) F + 2θo ⇒ H 2 O + 2θy(9) 2θr + O 2 ⇔ 2θo(10) CO + θo ⇒ CO 2 + θr(11) 2θx + O 2 ⇒ CO 2 + 2θr(12) 2θy + O 2 ⇒ 2CO 2 + 2CO + 2θrWhere: A=C 8 H 10 (o-Xylene = OX); B=C 8 H 8 O; C=C 8 H 8 O 2 ; D=C 8 H 6 O 2 ; E=C 8 H 4 O 3(Phthalic Anhydride = PA); F= C 4 H 2 O 3 (Maleic Anhydride = MA); θo and θr are53