Browsing by Author "Cechetto, Valentina"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item H2 production via ammonia decomposition in a catalytic membrane reactor(2021-06-01) Cechetto, Valentina; Di Felice, Luca; Medrano, Jose A.; Makhloufi, Camel; Zuniga, Jon; Gallucci, Fausto; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSThe membrane reactor is proposed in this work as a system with high potential to efficiently recover the hydrogen (H2) stored in ammonia (NH3), which has been recently proposed as an alternative for H2 storage. With this technology, NH3 decomposition and high-purity H2 separation are simultaneously performed within the same unit, and high H2 separation efficiency is achieved at lower temperature compared to conventional systems, leading to energetic and economic benefits. NH3 decomposition was experimentally performed in a Pd-based membrane reactor over a Ru-based catalyst and the performance of the conventional packed bed reactor were used as benchmark for a comparison. The results demonstrate that the introduction of a membrane in a conventional reactor enhances its performance and allows to achieve conversion higher than the thermodynamic equilibrium conversion for sufficiently high temperatures. For temperatures from and above 425 °C, full NH3 conversion was achieved and more than 86% of H2 fed to the system as ammonia was recovered with a purity of 99.998%. The application of vacuum at the membrane permeate side leads to higher H2 recovery and NH3 conversions beyond thermodynamic restrictions. On the other hand, the reactor feed flow rate and operating pressure have not shown major impacts on NH3 conversion.Item Hydrogen permeation studies of composite supported alumina-carbon molecular sieves membranes: Separation of diluted hydrogen from mixtures with methane: Separation of diluted hydrogen from mixtures with methane(2021-05-28) Llosa Tanco, Margot A.; Medrano, Jose A.; Cechetto, Valentina; Gallucci, Fausto; Pacheco Tanaka, David A.; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSOne alternative for the storage and transport of hydrogen is blending a low amount of hydrogen (up to 15 or 20%) into existing natural gas grids. When demanded, hydrogen can be then separated, close to the end users using membranes. In this work, composite alumina carbon molecular sieves membranes (Al-CMSM) supported on tubular porous alumina have been prepared and characterized. Single gas permeation studies showed that the H2/CH4 separation properties at 30 °C are well above the Robeson limit of polymeric membranes. H2 permeation studies of the H2–CH4 mixture gases, containing 5–20% of H2 show that the H2 purity depends on the H2 content in the feed and the operating temperature. In the best scenario investigated in this work, for samples containing 10% of H2 with an inlet pressure of 7.5 bar and permeated pressure of 0.01 bar at 30 °C, the H2 purity obtained was 99.4%.Item Ultra-pure hydrogen production via ammonia decomposition in a catalytic membrane reactor(2022-06-08) Cechetto, Valentina; Di Felice, Luca; Gutierrez Martinez, Rocio; Arratibel Plazaola, Alba; Gallucci, Fausto; Tecnalia Research & Innovation; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSIn this work two alternatives are presented for increasing the purity of hydrogen produced in a membrane reactor for ammonia decomposition. It is experimentally demonstrated that either increasing the thickness of the membrane selective layer or using a small purification unit in the permeate of the membranes, ultra-pure hydrogen can be produced. Specifically, the results show that increasing the membrane thickness above 6 μm ultra-pure hydrogen can be obtained at pressures below 5 bar. A cheaper solution, however, consists in the use of an adsorption bed downstream the membrane reactor. In this way, ultra-pure hydrogen can be achieved with higher reactor pressures, lower temperatures and thinner membranes, which result in lower reactor costs. A possible process diagram is also reported showing that the regeneration of the adsorption bed can be done by exploiting the heat available in the system and thus introducing no additional heat sources.