Process Intensification of Steam Reforming for Hydrogen Production

Abstract

Hydrogen is considered to be an efficient, clean and environmental, viable energy carrier in the 21st century [1]. Generally, there are many ways to produce hydrogen from both fossil fuels and renewable energy such as solar, wind, geothermal energy and so on [2,3]. Yet it is a realistic and practicable method for hydrogen production through hydrocarbon fuel reforming in the near future [7]. In the three types of fuel reforming technologies, namely steam, partial oxidation, auto-thermal reforming, steam reforming has the advantages of low reaction temperature, low CO content and high H2 content in the products and that is very favorable for mobile applications such as Proton Exchange Membrane Fuel Cell (PEMFC) [4,5]. However, steam reforming (SR) of hydrocarbon fuels is usually strongly endothermic reaction, the process of SR is often limited by heat and mass transfer in the reactors, so it presents a slow reaction kinetics which is characterized by low dynamic response and cold spot in the reactor catalyst bed [6]. Therefore, study of process intensification and optimization of SR for hydrogen production becomes important for the improvement of the reactor performance by enhancing heat and mass transfer and this can be divided to three classes. One way is to adopt new catalyst materials and additives such as coating catalyst, nanometer particle catalyst and so on to enhance the catalytic reforming reaction process [7]; another way is to reduce size scale of reaction channels in steam reforming reactors, for example, using micro-reactors instead of conventional reactors, which can reduce the heat and mass transport resistance by decreasing the transport distance [8]; in addition, microwave direct heating and membrane separation technology are also used to intensify the strongly endothermic SR process [9]. In this chapter, it is studied and stated that methanol and methane are taken as model hydrocarbon fuels for hydrogen production by steam reforming technology and effective process intensification methods of micro-reactor and coating catalyst. The innovative stainless steel micro-reactors which can be used to adopt both kernel catalyst and coating catalyst was designed and fabricated. A novel catalytic coating fabrication method of cold spray technology was also proposed. Experiments and simulation studies were carried out on methanol steam reforming (MSR) and steam methane reforming (SRM) in the microreactor on kernel and coating catalyst respectively.