The development of a chemical industry characterized by resource efficiency, in particular with reference to energy use, is becoming a major issue and driver for the achievement of a sustainable chemical production. From an industrial point of view, several application areas, where energy saving and CO₂ emissions still represent a major concern, can take benefit from the application of membrane reactors. On this basis, different markets for membrane reactors are analyzed in this paper, and their technical feasibility is verified by proper experimentation at pilot level relevant to the following processes: (i) pure hydrogen production; (ii) synthetic fuels production; (iii) chemicals production. The main outcomes of operations in the selected research lines are reported and discussed, together with the key obstacles to overcome.

The aim of the present work is the recycling treatment of tubular α-Al₂O₃-supported ceramic membranes with a Pd/Ag selective layer, employed in hydrogen production with integrated CO₂ capture. A nitric acid leaching treatment was investigated, and recovered ceramic supports were characterized, demonstrating their suitability for the production of novel efficient membranes. The main objective was the metal dissolution that preserved the support integrity in order to allow the recovered membrane to be suitable for a new deposition of the selective layer. The conditions that obtained a satisfactory dissolution rate of the Pd/Ag layer while avoiding the support to be damaged are as follows: nitric acid 3 M, 60 °C and 3.5 h of reaction time. The efficiency of the recovered supports was determined by nitrogen permeance and surface roughness analysis, and the economic figures were analysed to evaluate the convenience of the regeneration process and the advantage of a recycled membrane over a new membrane. The experimentation carried out demonstrates the proposed process feasibility both in terms of recycling and economic results.

Pd-based membrane reactors are strongly recognized as an effective way to boost H2 yield and natural gas (NG) conversion at low temperatures, compared to conventional steam reforming plants for hydrogen production, thereby representing a potential solution to reduce the energy penalty of such a process, while keeping the lower CO2 emissions. On the other hand, the exploitation of solar energy coupled with a membrane steam reformer can further reduce the environmental impact of these systems. On this basis, the paper deals with the design activities and experimentation carried out at a pilot level in an integrated prototype where structured catalysts and Pd-based membranes are arranged together and thermally supported by solar-heated molten salts for steam reforming reaction

Cordierite honeycomb structured catalysts were studied for the reaction of H₂S decomposition in the presence of oxygen to obtain H₂ and sulphur. An Al₂O₃-based washcoat was deposited on the honeycomb monolith by a dip-coating procedure. In particular, three different washcoat percentages (15, 20 and 30 wt%) were deposited on the structured carrier and the obtained samples were characterized by N₂ adsorption and SEM analysis. The evaluation of the catalytic performance of the three samples was carried out at two different temperatures (1000 °C and 1100 °C). The sample with 30 wt% washcoat content showed the lowest SO₂ selectivity at 1000 °C (<0.4%), whereas the H₂S conversion and H₂ yield values were very similar to those achieved for the samples at 15 and 20 wt% washcoat loading. Based on these results, additional tests were carried out on the catalyst with 30 wt% Al₂O₃-based washcoat loading, varying the contact time and the H₂S inlet concentration to identify the operating conditions that minimize the SO₂ formation, obtaining good H₂S conversion and H₂ yield. The comparison of the structured catalyst with the powder alumina sample has shown the same catalytic performance, exhibiting lower SO₂ selectivity.