Pure hydrogen from biogas: Intensified methane dry reforming in a two-zone fluidized bed reactor using permselective membranes

Abstract

Methane dry reforming of biogas can be a sustainable source of hydrogen but the development of this technology is hindered by limitations such as endothermicity and catalyst deactivation by coke. A two zone fluidized bed reactor coupling permselective Pd/Ag membranes counteracts them and allows to intensify the process obtaining a stable pure hydrogen production. Here we report the effect of operation variables (i.e., temperature, total bed height, nature and partial pressure of regenerative agent, relative height of the regeneration and reaction zones, and use of an activation period) on the yield to hydrogen and stability of the process. Hydrogen over-yields, compared with the conventional fluidized bed reactor, in the range of +200% to +100% were obtained for the entire interval of temperatures 475-575°C whilst maintaining stable operation by continuous catalyst regeneration. Around 70% of it was pure hydrogen coming from the permeate side of the membranes. The proposed reactor configuration greatly increases both methane conversion and selectivity to hydrogen (expressed as H 2 /CO ratio), not only in relation to our own conventional reactor findings but also regarding other published results.

Sustainable H2 generation via steam reforming of biogas in membrane reactors: H2S effects on membrane performance and catalytic activity

“…On the other hand, only a few studies deal with the utilization of Pd-based MRs to carry out the steam reforming of a real or synthetic biogas stream. In these studies, both fluidized bed [31,37] and packed bed [32][33][34][35][36]38,39] MR modalities were analyzed with the purpose of producing high grade hydrogen using synthetic H2S free biogas mixtures [31][32][33][34], or considering a pre-treatment step useful to remove H2S prior to the reforming stage [40][41][42]. In particular, Ru/Al2O3 catalyst and a thick self-supported Pd-Ag membrane (200 m) were used by Itoh's group [32,33], while Ni-based catalysts were packed in self-supported Pd-Ag [38,39] and supported Pd (7 m layer)/Al2O3…”

“…MRs [36]. To the best of our knowledge, in only one case a commercial Rh-based catalyst was used in a fluidized bed MR housing a supported Pd-Ag (5 m layer)/Al2O3 membrane [31].…”

Preparation, Characterization, and Activity of Pd/PSS-Modified Membranes in the Low Temperature Dry Reforming of Methane with and without Addition of Extra Steam

“…Most experimental reports concern the simultaneous dry and steam reforming of methane in a conventional reactor at high-temperature [ 16 , 26 , 27 ]. Some works related to dry reforming of methane [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ] or steam reforming of methane in a MR were also reported [ 36 , 37 ]. There are also studies combining steam and dry reforming (biogas reforming) in an MR [ 38 , 39 , 40 ].…”

Thermochemical Performance Analysis of the Steam Reforming of Methane in a Fixed Bed Membrane Reformer: A Modelling and Simulation Study

“…The Pd-based dense membrane can act as a remover and it facilitates the selective removal of the gaseous molecule of H 2 . The removal of H 2 through Pd-based dense membrane shifts the equilibrium of reforming reactions to the chosen direction according to the Le Chatelier principle [7][8][9]. PBMRs offer many potential advantages such as enhanced conversion of hydrocarbons, reduced cost, improved yield, and high selectivity.…”