Membranes for Pure Syn-Gas Generators
Development of High-Performance Oxygen-Conducting Membranes and Compact Pure Syn-Gas Generators on Their Base
Tech Area / Field
- CHE-IND/Industrial Chemistry and Chemical Process Engineering/Chemistry
8 Project completed
Senior Project Manager
Russo P A
VNIIEF, Russia, N. Novgorod reg., Sarov
- Belarussian State University / Institute of Physical Chemical Problems, Belarus, Minsk\nBoreskov Institute of Catalysis, Russia, Novosibirsk reg., Akademgorodok\nKarpov Institute of Physical Chemistry, Russia, Moscow
- CNRS / Institute de Recherches sur la Catalyse, France, Paris\nUniversity of Connecticut / School of Engineering, USA, CT, Storrs\nImperial College London / Department of Materials, UK, London
Project summaryThe fuel cell (FC)-based power plants (PP) that provide direct transformation of chemical energy into electrical one are now considered as a priority trend in the development of power engineering and motor transportation. Most FC use hydrogen or syn-gas (a mixture of hydrogen and carbon oxide) as fuel. A considerable share of the PP cost falls at the syn-gas reactor. Hence, the efficient and cost-saving technology of syn-gas generation is an essential step towards the FC – based PP wide-scale application.
Traditionally, syn-gas is generated through an endothermic process of methane steam reforming, which is associated with high energy consumption and requires bulky and expensive equipment.
The selective methane oxidation by the atmospheric oxygen using a specially developed catalyst is the most promising method of syn-gas generation. However, the ballast nitrogen in such syn-gas decreases the efficiency of flow-through fuel cells and makes the operation of static fuel cells impossible.
The alternative technologies are based upon the use of oxygen-conducting membranes with mixed conductivity for separating oxygen from the air in combination with methane selective oxidation into syn-gas by the recovered oxygen in the same reactor.
However, the given technology is still not commercially attractive. This is mainly due to the tough requirements that the membranes should satisfy. They must not just provide high oxygen conductivity (~ 10+ cm3 Î2/cm2 min) at temperatures ranging between 700-1000 °С, but they must also have high mechanical strength, chemical and phase stability under the conditions of high gradients of oxygen chemical potential (pure methane on the one side of a membrane and the air – on the other side). They must also be corrosion- and poison- resistant and compatible with the supported catalysts and construction materials. However till now, not a single available membrane material could meet all the needed criteria.
In the Project, we propose to carry out a series of scientific and research works on the synthesis of efficient and stable composite catalytic membranes to convert methane (natural gas and/or heavier hydrocarbons) into a high-clean (nitrogen-free) syn-gas using the air- and air-steam reforming and on the creation of compact air and/or air-steam reforming systems on their base.
The main requirements for the oxygen-conducting membranes will be met using the following methodical approaches:
- Highly porous tubular ceramic supports with a low gas-dynamic resistance will be coated by a thin compact layer of stable composite oxide electrolyte with mixed conductivity.
- Supports on the base of corundum, partially stabilized zirconium dioxide and complex framework zirconium phosphates will be used as construction nanocomposite materials. The adjustment of their porous structure and the needed shaping will be effected applying the on-site know-how and the available equipment to produce ceramic complex shape products.
- High oxygen conductivity of the coating electrolyte layer with mixed conductivity will be provided due to its small (< 1 micrometer) thickness as well as by applying unique methods of such conductors’ synthesis (combination of mechanochemical activation and polymerized precursors method). The adjustment of their structure and composition will ensure the stabilized high defectiveness and, as a result, high conductivity.
- Complete blocking of nitrogen transfer through such a membrane will be provided by high uniformity and compactness of the electrolyte surface layer, which is achieved by purposeful adjustment of the membrane support porous structure and through the special coating techniques applying inorganic/organic composite precursors.
- High rate of interaction between methane and oxygen transferred through the membrane is required to provide high efficiency of the membrane reactor as a whole. That will be ensured by coating special-purpose catalytically active components enabling high rate of methane transformation into syn-gas at short contact times.
Expected results upon the Project completion:
- We shall create oxygen-conducting membranes, which being strong and stable in real aggressive media of the processes of syn-gas generation may provide high oxygen conductivity up to 10 cm3 Î2/cm2 min at temperatures ranging between 700-900°С and the electron resistance of 1-0.1 Ohm cm-2;
- Based on the membranes, a high-clean syn-gas generator will be developed with the following characteristics:
- efficiency of methane conversion into syn-gas - 1,5-2 m3 of methane /h
- start-up period from the cold state to syn-gas generation mode of 1-10 s
- syn-gas generator volume not exceeding 10 l.
A team of highly skilled specialists mostly involved in weapon programs will implement the Project. RFNC-VNIIEF and other Institutions - participants have the needed scientific and technical potential in synthesis of functional ceramics and catalysts and creation of fuel processors for the FC-based PP. They also possess high technologies to create a compact and cost-saving catalytic unit for the production of high purity syn-gas from methane and other hydrocarbons using the membrane technologies. The man-effort of the scientists and specialists – weapon developers amounts to 270 man/months or 54 % from the total man-effort of the participants.
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