Graphene patents and applications keep pouring in. This week 14 new patents and/or applications were published.
The most interesting patent application (number 20160074813) comes from Airbus. The invention employs graphene in the floor of an aircraft fuel tank. The floor is designed to let unwanted water drain out, while keeping the fuel in.
In the words of Airbus, as part of the invention background:
“Water contamination in aircraft fuel tanks can cause many problems with the aircraft fuel systems. As the aircraft reaches altitude, the ambient temperature drops to around −50° C. which leads to ice formation in the fuel tank. This can lead to gauging errors and failures, clogging of the fuel pumps and interference with fuel pump pressure switches. The presence of water in the fuel tank can also lead to the growth of micro biological contamination (MBC) which can lead to similar problems. It is therefore desirable to remove the water from the fuel tank before these problems occur.
A conventional method for draining water from fuel tanks involves providing water drain valves on the floor of the fuel tank. However, these water drain valves are typically unable to discriminate between water and fuel. The consequences of this are that fuel is lost from the tank when water is drained and that often insufficient water is removed to prevent the above problems. Moreover, an operator is required to drain the water from the fuel tanks when the aircraft is grounded. This method is therefore also expensive and time consuming.
“Unimpeded Permeation of Water Through Helium-Leak—Tight Graphene-Based Membranes”, R. R Nair et al, Science, 27 Jan. 2012, Vol. 335, no. 6067, pp. 442-444, DOI:10.1126/science.1211694 (referred to below as “Nair et al”) demonstrated that that submicrometer-thick membranes made from graphene oxide can be completely impermeable to liquids, vapors, and gases, including helium, but these membranes allow unimpeded permeation of water.”
Aside from graphene-oxide membranes, the inventors consider using other materials with nanoholes, or vertically aligned hollow carbon nanotubes. The challenge is to design a membrane that will sustain pressures up to 1.6 atmospheres, which develop due to the large tank volumes and airplane acceleration.
Permeable graphene membranes are clearly a hot technology, with another two patent applications this week. One (application number 20160074814), coming from Hanyang University in Korea, describes a composite graphene-polymer membrane that helps trap carbon dioxide, for example from power plant emissions. Again the material used is graphene oxide, in combination with a porous polymer. The idea is to have a membrane that captures CO2 while letting other gases pass. Another patent application (number 20160074815, clearly submitted just after the one from Hanyang) comes from Lockheed Martin Corporation. Although the wording is different, the idea is basically the same – a graphene composite membrane to separate CO2. The Lockheed Martin invention is more general, allowing not only polymer but also ceramics, zeolytes, and other materials in combination with graphene. It also specifies other possible separation uses, not all related to CO2. It will be interesting to see how this plays out, with two such similar applications being filed at the same time.
Other than that, the most recently published applications include various methods of producing graphene, thermal conduction composites, and the ever-present graphene electrode.