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CLIMIT-Forskning, utvikling og demo av CO2-håndtering

Enhanced lifetime of Pd-based membranes

Alternative title: Forlenget levetid for palladium-baserte membraner

Awarded: NOK 4.9 mill.

Hydrogen will selectively diffuse through palladium membranes, and in combination with large scale conversion of natural gas, this is a very efficient way of producing pure hydrogen, while at the same time containing carbon dioxide. The carbon dioxide can then be stored in underground cavities. This project will gain new knowledge about long term effects on the membranes, and the effect on life time. Theoretical work, combined with laboratory experiments, shall identify important parameters, and based on this, new alloys will be produced. Long term testing of these alloys, both in laboratory and pilot scale, will give new knowledge on how to increase the life time. Pilot scale experiments will also give important knowledge about the operating conditions. The project has performed the development of theoretical models for membrane behaviour. Among other things, we have completed models for vacancy and defects formation in bulk palladium and near grain boundaries and have expanded this work with the effect of alloying elements. Based on these models, new alloys can be identiefied. Preparation of membranes for initial laboratory testing is also started. Palladium membranes have been tested over 500 hours at 400 degree C and analysed using high resolution SEM / TEM. Based on the results it can be concluded that hydrogen has an influence on the defect formation. New and optimised parameters for production of palladium membranes is developed and implemented. It is also developed a procedure for start-up, operation and shutdown of palladium-membranes. The procedure is implemented during the prototype and pilot testing. The initial test program and test matrix for the prototype testing is finalized. Membrane mechanical strength in an industrial use is important for the robustness and life time. A method for metallic bonding between membrane and carrier is developed and is important for achieving this robustness. Such bonding is achieved for the prototype and pilot. The project has so far resulted in three scientific publications, while one more is in preparation.

En robust membran som kan benyttes i industrielle løsninger. Oppstarts- og nedstegningsprosedyrer som er nødvendig for praktisk utnyttelse av membran i industriell drift. Teoretiske modeller som kan brukes til å finne nye membranlegeringer som vil kunne øke levetid på membran.

Palladium (Pd) based membranes have received great attention from both academia and industry because of their ability to selectively separate hydrogen from gas streams. Integration of such membranes with appropriate catalysts in membrane reactors allows for hydrogen production with CO2 capture that can be applied in smaller bioenergy or combined heat and power (CHP) plants, as well as large-scale power plants. Pd-based membranes are therefore regarded as a Key Enabling Technology (KET) to facilitate the transition towards a knowledge-based, low carbon and resource-efficient economy. The large potential of the technology in CO2 capture and H2 production, manifested by the economic support from public and industrial sectors, has tremendously progressed the dense Pd-based membrane technology forward. The limited knowledge of the changes of the membrane performance over time and during start-up and shut-down procedures, however, is one of the main concerns in bringing this technology to the market. Even though stable membrane operation of more than one year has currently been obtained at temperatures of 300-500 degC and a pressure difference of 30 bars, one of the observations is that the selectivity decreases over time decreasing the membrane lifetime. Consequently, the purity of the hydrogen produced reduces. Improved Pd-alloys and composite membrane structures are hence needed for the next generation of H2 separation membranes. This is a very challenging topic, since pinhole formation is expectedly governed by several factors on different time- and length scales. To solve this problem a further insight of degradation mechanisms is required. The project will be organised along two axes: 1. A material approach where the aim is to alloy the Pd-layer with small amounts of high melting alloying elements 2. A process approach, where different strategies during start and stop cycles will be evaluated

Funding scheme:

CLIMIT-Forskning, utvikling og demo av CO2-håndtering