Modeling chemical looping syngas production in a microreactor using perovskite oxygen carriers

Abstract

Synthesis gas, a mixture of hydrogen and carbon monoxide, could be produced in a chemical looping process. The objective of this work is the modeling of syngas production in a fixed bed microreactor by chemical looping reforming. A perovskite oxygen carrier was used for the reduction of methane to syngas. Twenty one gas-solid kinetic models were applied to the experimental data in which their parameters were estimated using an optimization code. The results show that among all models, reaction order model is the most preferable choice with satisfactory fitting criteria. The gas-solid model was coupled with a catalytic scheme to predict not only the conversion of perovskite oxygen carrier, but also the catalytic performance of the solid particles for syngas production. The kinetic parameters of the unified model were evaluated based on the experimental data of a fixed bed reactor. Analysis of both perovskite and nickel oxide, oxygen carriers shows that perovskite particles could convert 50 times slower than those of nickel oxide. A H2/CO ratio of below 10 was obtained in a period of time. A large amount of hydrogen was produced after completing gas-solid reactions which was due to cracking of methane to carbon and hydrogen. Although hydrogen was the main outlet product afterwards, corresponding carbon formation is a problem which should be avoided. The reduction of methane was proposed before 500 s with a carbon formation of below 0.04 kg carbon per one kg of perovskite carrier. Solid reduction conversion, methane consumption and product distribution were analyzed inside the microreactor.