## 1 Introduction  
Although the development of energy transition solutions in terms of renewable energy such as solar, wind, and clean fuels (e.g., hydrogen) are widely spreading, it appears increasingly evident that the short-term reduction of fossil fuel exploitation is an even more urgent and challenging process. The implementation of short- to mid-term options towards a low-carbon world, acting at the source to prevent carbon emissions, proves to be crucial [1]. Among these decarbonization strategies, the increased support and deployment of carbon capture technologies and low-carbon hydrogen infrastructure are included [2]. Hydrogen is widely recognized as a technically viable and environmentally friendly energy carrier for applications ranging from small-scale off-grid power supply to large-scalechemical power export [1]. The deployment of hydrogen as an alternative energy carrier is severely limited by the lack of low-cost hydrogen generation, storage, transportation, and conversion technologies [3]. Global hydrogen demand, which reached 97 Mt in 2023, is concentrated in the refining (42%) and chemical sectors, mainly as feedstock to produce ammonia (35%) and methanol (15%). The entire demand is essentially covered by hydrogen produced from fossil fuels [4; 5]. Based on announced projects involving electrolysis and fossil fuels with carbon capture, utilization, and storage (CCUS) to obtain, respectively, the so-called green or blue hydrogen, low-emission hydrogen production could significantly increase by 2030 [4]. Potential new applications include the use of hydrogen as a reducing agent in 100%-hydrogen direct reduced iron (DRI), long-distance transport, the production of hydrogen-based fuels, biofuel upgrading, high-temperature heating in industry, and electricity storage and generation. Global hydrogen production emitted 920 Mt CO\({}_{2}\) last year, with natural gas representing the source of nearly two-thirds of the entire production [4]. Around 50% of the global hydrogen production from natural gas (gray hydrogen) relies on steam methane reforming (SMR), the most cost-effective process [6]. This process is operated at a high pressure (20-30 bar) and high temperature (800-900 \({}^{\circ}\)C) in a reformer where the following highly endothermic reactions occur:  
\[\mathrm{CH_{4}+H_{2}O\leftrightarrow 3H_{2}+CO}\qquad\qquad\mathrm{\Delta H_{298K} =206.4 kJmol^{-1}} \tag{1}\]  
\[\mathrm{CH_{4}+2H_{2}O\leftrightarrow 4H_{2}+CO_{2}}\qquad\qquad\mathrm{\Delta H _{298K}=165 kJmol^{-1}} \tag{2}\]  
While high temperatures meet the thermodynamic requirements, high pressures, which disadvantage thermodynamics, are operated since they are economically viable based on several assessments including, for example, the cost of gas compression that, if carried out downstream, would involve a higher number of moles. The syngas from the reformer is then fed to a shift converter, where the water-gas shift (WGS) reaction takes place:  
\[\mathrm{CO+H_{2}O\leftrightarrow H_{2}+CO_{2}}\qquad\qquad\mathrm{\Delta H_{298 K}=-41.1 kJmol^{-1}} \tag{3}\]  
Traditionally, Ni-based catalysts, presenting a good price-to-activity ratio, are applied in the SMR process. This technology, although well established, presents important limitations, such as the high temperatures and pressures needed, with consequent energy-intensive operations, numerous steps involved, and low hydrogen yields (\(<\)80%), which must be improved to enable the large-scale implementation of hydrogen as an energy carrier. Moreover, the process is associated with large emissions of CO\({}_{2}\) in the atmosphere after the purification steps of the raw gas product [1; 7]. The application of CCS technology to SMR entails a cost penalty of about USD 76/t\({}_{\mathrm{CO2 captured}}\) and a reduction of the overall process efficiency (65-70%).