Russian scientists have created a new nanoporous material for gas storage. The new material allows increased gas absorption at low pressure and room temperature, thus eliminating the need for heavy, thick-walled cylinders. A lightweight cylinder with such a nanofiller will not explode and can be used in passenger cars. The study was published in Chemical Engineering Journal.
Natural gas is an attractive alternative to petrol. When used as a vehicle fuel, methane can offer carbon monoxide and nitrogen oxide emissions benefits over conventional fuel. Methane is also cheaper than petrol or diesel.
However, the use of natural gas as a vehicle fuel is associated with a number of technological challenges. Methane requires either high-pressure compression or low-temperature liquefaction, which are expensive and potentially pose severe hazard. In order to produce compressed natural gas (CNG), methane is pressurized in a methane compressor. CNG storage tanks must represent pressure vessels and, as a result, have limited geometry and sufficiently high weight. All these factors hinder the widespread use of methane as a transport fuel.
A promising alternative to compression is adsorption. The adsorbed natural gas storage systems operate at lower pressures, use cheaper equipment and appear to be the safest way to store the methane and, consequently, create alternative opportunities for making methane vehicles competitive with the other types of vehicles. The adsorbent is a key link in the ANG technology. Depending on its characteristics, the adsorption capacity and working capacity be different.
A Russian-Indian research team has created a new nanoporous carbon material that has an increased adsorption ability, which was achieved by increasing the density of the material while maintaining high micropore volume. Thus, a smaller amount of the adsorbent is able to hold a larger amount of gas in its micropores.
“The synthesis was carried out by converting a mixture of polymer compounds into a nanoporous carbon material, followed by its formation into blocks of the desired size and shape. The developed material has a high surface area and pore volume, more than 80% of which are narrow micropores. The developed material surpasses all currently known commercial adsorbents in terms of the achieved values of the total volumetric capacity of methane accumulation, which is 336 cm3/cm3 at a pressure of 100 bar. For comparison, the standard volumetric specific capacity of methane adsorbents set by the US Department of Energy is 236 336 cm3/cm3,” said Anastasia Memetova, Associate Professor at the Department of Engineering and Technologies for the Production of Nanoproducts, Tambov State Technical University.
The authors of the study note that due to the absence of the need to use heavy-duty cylinders for storage and transportation, the use of the developed adsorbent will significantly reduce the cost of methane for the end user and expand its use as a transport fuel.
“A vehicle’s weight is one of the key factors affecting fuel consumption. The heavier the vehicle, the more energy it needs to get moving. Thus, ditching heavy-duty cylinders would save car owners some pennies. Moreover, our system operates at much lower pressure, which means better safety,” added Igor Burmistrov, leading expert at the Department of Functional Nanosystems and High-Temperature Materials, NUST MISIS.
The nanocarbon material created by the team can also be used for storing other toxic gases, such as carbon monoxide and carbon dioxide, as well as various nitrogen oxides.