Iron and steel is an energy intensive industry and its contribution to the pollution of environment is considerable. Direct reduction iron (DRI) is a major element of an iron and steel production plant. Its share in natural gas and electricity consumption of total plant is estimated to be 70% and 15% respectively. Reduction gases are produced in natural gas reforming unit and its elements are CO and H2. A major consequence of using this technology is high level of CO2 emission, which pollutes the environment. An alternative to the existing technology is utilization of H2 as reducing agent. A comparison of various hydrogen production processes indicate that thermal decomposition of methane provides an attractive option from economical and technical point of view. Therefore, a system for producing hydrogen, based on thermal decomposition technique, has been designed in the framework of the present paper.

The effects of potassium promoter for production of heavy hydrocarbons from SYNGAS with silica- supported cobalt catalysts has been studied. After preparing the catalysts in accordance with the sol-gel method, they were subjected to various tests by using a small steely micro-reactor and capable of operating in diversified situations, such as stable temperature range, flow rate, space velocity, etc. Thorough observations revealed that the conducive situations can be achieved by  the ratio of H2/CO=2  with a temperature of 220 oC, whereas the flow rate of CO and N2 components must be equal  about 35 ml/min.

Typically, supporting the DME synthesis reactor by hydrogen and H2O permselective membrane modules and optimization of operating condition are practical solutions to shift the equilibrium conversion of reactions toward DME production and increasing CO2 conversion in the direct synthesis route. In this regard, the main object of this research is calculating the optimal condition of the dual membrane reactor to enhance DME productivity. In the first step, the considered dual membrane reactor is heterogeneously modeled based on the mass and energy governing equations. Since the reactions are intraparticle mass transfer control, the effectiveness factor is calculated and applied in the model. In the second step, a single objective optimization problem is formulated considering process limitations and constraints to calculate the optimal condition of the dual membrane process. Then, the performance of the dual membrane and conventional processes are compared at steady state condition. Based on the simulation results, DME production rate in the optimized dual membrane and conventional reactors are 0.0211 and 0.0262 mole s-1, respectively. Applying the optimal condition on the system increases DME production about 24.17% compared to the conventional process.