(152z) Effect of Steam and Air on Methane Dry Reforming Reaction in Pd-Au Membrane Reactor for Hydrogen Production

The methane dry reforming (MDR) process has attracted attentions due to utilization of two main greenhouse gases, CO₂ and CH₄, to produce synthesis gas, H₂ and CO. This process can be applied not only to particular exhaust stream, but also to biogas, which consists of CH₄ (55–75 vol%) and CO₂ (25–45 vol%). The MDR is endothermic reaction, and it is usually performed at high temperature, as 700–900 °C and pressure of 15–30 bar due to thermodynamic constraint [1,2]. In addition, several side reactions occur in the system including reverse water gas shift, methanation, methane decomposition and Boudouard reaction with carbon deposition [1,2].

Alternative option to conventional reactor (CR) is the hydrogen-selective membrane reactor (MR). The MR is a device where reaction and separation happen simultaneously. Particularly, the presence of the membrane allows for hydrogen removal from the reaction zone which pushes the reaction towards more products formation, according to Le Chatelier principle. As a results, it is likely to reach higher conversion at same temperature or perform the reaction at lower temperature to obtain same conversion in comparison with CR. Also, the removal of hydrogen from the reaction zone with MR prevent the reverse water gas shift and methanation side reactions which decrease the efficiency of system for hydrogen production [3,4]. The palladium-based MRs are appropriate choice for hydrogen production and separation because of their complete selectivity towards hydrogen permeation. The Pd-alloys membranes have shown advantages over pure Pd in terms of hydrogen permeability, fabricating cost, higher chemical and physical stability. For example, the Pd-Ag membranes have indicated higher permeation, while Pd-Au membranes have higher chemical and physical stability and better permeability than pure Pd membranes [3–6].

In this work, MDR reaction is conducted on Pd-Au over nickel catalyst to produce hydrogen at different temperatures and pressures. The Pd-Au membrane is synthesized by electroless plating and deposited on porous stainless steel tubular support. Also, the effects of addition of steam and air are investigated on the Pd-Au performances MR in terms of carbon dioxide conversion, hydrogen recovery and yield and long-term stability. Finally, pristine and used membranes are characterizized by Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), and X-ray diffraction (XRD).

References

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[2] J.M. Leimert, J. Karl, M. Dillig, Dry reforming of methane using a nickel membrane reactor, Processes. 5 (2017). https://doi.org/10.3390/PR5040082.

[3] F. Gallucci, S. Tosti, A. Basile, Pd-Ag tubular membrane reactors for methane dry reforming: A reactive method for CO2 consumption and H2 production, J Memb Sci. 317 (2008) 96–105. https://doi.org/10.1016/j.memsci.2007.03.058.

[4] F.R. García-García, M.A. Soria, C. Mateos-Pedrero, A. Guerrero-Ruiz, I. Rodríguez-Ramos, K. Li, Dry reforming of methane using Pd-based membrane reactors fabricated from different substrates, J Memb Sci. 435 (2013) 218–225. https://doi.org/10.1016/j.memsci.2013.02.029.

[5] T.Y. Amiri, K. Ghasemzageh, A. Iulianelli, Membrane reactors for sustainable hydrogen production through steam reforming of hydrocarbons: A review, Chemical Engineering and Processing - Process Intensification. 157 (2020). https://doi.org/10.1016/j.cep.2020.108148.

[6] J.J. Conde, M. Maroño, J.M. Sánchez-Hervás, Pd-Based Membranes for Hydrogen Separation: Review of Alloying Elements and Their Influence on Membrane Properties, Separation and Purification Reviews. 46 (2017) 152–177. https://doi.org/10.1080/15422119.2016.1212379.