Kinetic modeling of catalytic cracking of C4 alkanes over La/HZSM-5 catalysts in light olefin production

•Mechanism of catalytic cracking of C4 alkanes over La/HZSM-5 zeolites.•Combining the theory of complex reaction and LHHW.•Deducing overall reaction rate of each molecular component.•Obtaining the intrinsic kinetic parameters of elementary reaction scheme.•Determining the contribution of prevailing reaction mechanism.

Kinetic modeling of catalytic cracking (CC) of C4 alkanes (mixture of i-butane and n-butane), over Lanthanum modified HZSM-5 catalyst has been studied at 582–630 °C in a plug flow reactor. The elementary reaction steps, i.e., protolytic cracking (PC) of CC and CH bonds in alkane molecules, hydrogen transfer between butane and light olefins, olefin cracking, β-scission, adsorption and desorption were taken into account. The combination of theory of reaction routes and LHHW has been employed in the complicated CC network to drive explicit overall reaction rate of reactantand product molecules. Then, the parameter estimation and model discrimination were performed based on the minimization of mean residual sum of squares between experimental and theoretical rates. The intrinsic kinetic parameters were estimated by non-linear least-square regression using MATLAB optimization toolbox.

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