CATALYTIC MEMBRANE REACTORS FOR HYDROGEN SEPARATION IN HYDROCARBON FEEDSTREAMS

摘要

Eltron Research Inc. and team members CoorsTek, McDermott Technology, S(u)d Chemie, and Argonne and Oak Ridge National Laboratories are developing dense multi-phase membranes for hydrogen separation in Vision 21 energy plants. This objective is being pursued using ceramics based in part on Eltron-patented materials with a demonstrated ability for proton and electron conduction. This technology addresses the Vision 21 initiative by offering a relatively inexpensive and environmentally benign process for hydrogen separation and purification. Ultimately, hydrogen separation at practical rates under relevant conditions must be achieved, without deactivation from feedstream components, such as carbon dioxide, water, and sulfur.Highest mixed proton and electron conductivity was observed for multi-phase compositions containing a combination of a predominantly proton-conducting phase and an electron-conducting phase. Multi-phase ceramics and ceramic/metal (cermet) compositions demonstrated mixed proton/electron conductivity between 10~(-3) and 10~(-2) S/cm, with corresponding hydrogen separation rates between 0.01 and 0.8 mL/min/cm~2 for thick membranes (0.16 to 1.0 mm) at high temperatures (700 to 950°C). Hydrogen transport through ceramic membranes was dependent on the concentration and identity of transition metal dopants and metal oxides included in the composition. Similarly, hydrogen transport through cermet membranes was dependent on the ceramic phase composition, as well as the volume percent of the electronic conducting phase. Furthermore, when a metal with high hydrogen-permeability was used in cermet compositions, a 0.43-mm thick membrane enabled hydrogen separation near 1.8 mL/min/cm~2.