Melchiori, Tommaso (PD)

Reactor selection for oxidative coupling of methane

T. Melchiori, F. Gallucci, M. van Sint Annaland

Room: STW 0.34, T.Melchiori@tue.nl

Introduction

Oxidative coupling of methane is a catalytic reaction through which methane is partially oxidized to form C2 hydrocarbons (ethylene and ethane), together with steam at high temperatures (~ 800 ºC). It represents an attracting way to produce ethylene, because of the currently relative low price of natural gas compared to oil. In spite of this, it has never found an application on industrial scale. As a matter of fact, it is extremely difficult to achieve both high methane conversion and C2 selectivity in an OCM process, because of the unavoidable side reactions, that mainly lead to complete combustion of methane to CO2 and steam, or consecutive complete combustion and reforming of the produced C2. This means high costs of separation and unit sizes on industrial scale. The process is also challenging from the point of view of thermal control, because of the highly exothermic reactions involved in the mechanism. Different kinds of reactor concepts have been studied to try to overcome these issues, with the most promising innovations being integration of N2/O2 separation and distributed O2 feeding inside the reactor.

Objective

Aim of the project is to study different kinds of reactors for OCM and evaluate which could be the most suitable concept. A first qualitative discrimination will be performed by considering the current state of the art. On a second step, a more restricted number of concept will be chosen for more detailed assessment. This will be done by carrying out simulations using mostly phenomenological models. The investigation includes packed beds, fluidized beds, membrane reactors, and chemical looping reactors. Reactor optimization and sensitivity studies on the operative variables will be also carried out. The project is financed by Shell.