Non-oxidative methane dehydroaromatization (MDA:6CH 4 ↔ C 6 H 6 + 9H 2 ) using shapeselective Mo/zeolite catalysts is a technology to exploit stranded natural gas reserves by direct conversion into transportable liquids. The reaction, however, faces two major issues: the onepass conversion/yield is limited by thermodynamics, and the catalyst deactivates fast due to the kinetically-favored formation of coke. Here we show that integration of an electrochemical BaZrO 3 -based membrane exhibiting both proton and oxide ion conductivity into an MDA reactor enables high aromatic yields and outstanding catalyst stability. These effects originate from the simultaneous extraction of hydrogen and distributed injection of oxide ions along the reactor length. Further, we demonstrate that the electrochemical co-ionic membrane reactor enables high carbon efficiencies (up to 80%) significantly improving the techno-economic process viability, and sets the ground for its commercial deployment. One Sentence Summary:The integration of a co-ionic membrane in a MDA reactor remarkably enhances aromatics yield and catalyst lifetime. Main text:

Conventional production of hydrogen requires large industrial plants to minimise energy losses and capital costs associated with steam reforming, water-gas shift, product separation, and compression. Here we present a protonic membrane reformer (PMR) which produces high purity hydrogen from steam methane reforming in a single-stage process with near-zero energy loss. We use a BaZrO 3 -based proton-conducting electrolyte deposited as a dense film on a porous Ni composite electrode with dual function as a reforming catalyst. At 800 °C, we achieve full methane conversion by removing 99 % of the formed hydrogen, which is simultaneously compressed electrochemically up to 50 bar. A thermally-balanced operation regime is achieved by coupling several thermo-chemical processes. Modelling of a small scale (10 kg H 2 day -1 ) hydrogen plant reveals an overall energy efficiency of >87 %. The results suggest that future declining electricity prices can make PMRs a competitive alternative for industrial-scale hydrogen plants integrating CO 2 capture.Membranes that simultaneously enable chemical reaction and product separation hold promise for process intensification 1-3 . Currently, the most energy efficient production pathway for hydrogen from methane combines steam reforming (CH 4 + H 2 O = 3H 2 + CO, ΔH 1073K = 226 kJ mol -1 ) and water-gas shift (CO + H 2 O = H 2 + CO 2 , ΔH 1073K = -34 kJ mol -1 ) in a multistep process 4 , where heat management is crucial. The produced hydrogen is conventionally separated downstream using e.g. pressure swing absorption (PSA) 5 . Alternatively, hydrogen separation can be included in the steam reforming process using hydrogen selective membranes 6,7 with the benefit of simultaneously separating hydrogen while shifting the thermodynamic equilibrium resulting in process intensification. Most practiced membranes are metallic, predominantly based on Pd or Pd-Ag alloys 8 . The separation is driven by the hydrogen partial pressure difference across the membrane, from which it follows that the pressure of the produced hydrogen is low, and further

Proton ceramic reactors offer efficient extraction of hydrogen from ammonia, methane, and biogas by coupling endothermic reforming reactions with heat from electrochemical gas separation and compression. Preserving this efficiency in scale-up from cell to stack level poses challenges to the distribution of heat and gas flows and electric current throughout a robust functional design. Here, we demonstrate a 36-cell well-balanced reactor stack enabled by a new interconnect that achieves complete conversion of methane with more than 99% recovery to pressurized hydrogen, leaving a concentrated stream of carbon dioxide. Comparable cell performance was also achieved with ammonia, and the operation was confirmed at pressures exceeding 140 bars. The stacking of proton ceramic reactors into practical thermo-electrochemical devices demonstrates their potential in efficient hydrogen production.

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