Ethylene from Methane and Naphtha by an Integrated Process

An integrated one-stage process of ethylene production from methane and naphtha, consisting of exothermic oxidative coupling of CH₄ over the catalyst fixed bed and endothermic pyrolysis of naphtha and of the formed C₂H₆ in the postcatalytic zone of the same reactor, was studied under varied operating parameters including CH₄/naphtha ratio, temperatures of the catalytic and postcatalytic zones, and flow rates of the reagents. The rationale of an integrated one-stage concept has been confirmed. High yields of C₂H₄ and coproducts were obtained. An additivity of the yields of oxidative coupling and pyrolysis was observed under experimental conditions. The increase in C₂H₄ yield, as compared with pyrolysis of naphtha, was proportional to the contribution of the coupling component. The C₂H₄/C₂H₆ mole ratio was found to be as high as 4-5 for oxidative coupling with partial pyrolysis of C₂H₆ and about 10 for the integrated process. Both air and oxygen can be used as oxidants in the coupling step. Depending on relative contributions of the coupling and pyrolysis components to the integrated process, an overall balance of CH₄ could be negative (consumption) or positive (production). In the latter case, the integrated process could be based only on a liquid feedstock, with a recycle of CH₄.