Mathematical Modeling of Catalytic Membrane Reactor

Abstract

Nowadays, most reactions in chemical and petrochemical industries are catalytic due to their enhanced effectiveness and reduced product cost. A packed-bed reactor is one of the most widely used type of the catalytic reactors. However, the packed-bed reactor has several disadvantages such as possible formation of hot spots in the reactor leading to catalyst deactivation, non-uniform reactant consumption, and risks of runaway and even explosion as well as structural maldistribution of catalyst pellets with low packing density close to the reactor wall and high density in the reactor center resulting in partial bypassing of reactants. A membrane reactor is the promising alternative to conventional packed-bed reactor. The membrane reactor combines the separation and chemical reaction processes in one unit. The permselective membranes are used for selective input of reactant or removal of product that can permeate through the membrane along the reactor length and as the catalyst support. This study is focused on modeling the partial oxidation of the methane process in the membrane packed-bed reactor. Nowadays, the production of synthesis gas from natural gas becomes more and more important in chemical and petrochemical industries. Currently, steam reforming is the most commonly used process of syngas production. However, this process consumes a large amount of energy because it involves highly endothermic and relatively slow reactions. One of the promising alternatives for hydrogen production is the partial oxidation of methane. The advantage of this reaction is the possibility to conduct the process in the smaller reactor due to faster oxidation. The partial oxidation of methane is a mild exothermic process carried out at high pressure and in the temperature range of 750 – 1200 K. Usually, pure oxygen is used as a source of oxidation and application of the membrane for selective supply of oxygen by separation from air could decrease the energy demand and the capital cost of the process significantly. In this research, a 2D non-isothermal model was derived for the packed-bed membrane reactor, a numerical algorithm was elaborated to solve the model equations, and the python software was developed to simulate the reactor performance. In addition, the parametric study was conducted to evaluate the effects of various parameters on the reactant consumption, product selectivity and yield in the partial oxidation of methane. Finely, it was possible to determine the process and reactor parameters enabling to achieve a similar performance of the membrane packed-bed reactor and the conventional packed-bed reactor.