What can farms and timber companies provide high performance aviation? If a Chinese research team continues to build on a new process, they may be able to convert plant scraps from agriculture and timber harvesting into quality jet fuel, helping to reduce carbon dioxide emissions from airplanes and rockets.
The study published on Thursday in the journal Joule showed that a cheap, renewable and abundant polymer in the plant’s cell walls can produce high-density aviation fuel.
“Our biofuel is important for mitigating CO2 emissions because it is derived from biomass and it has higher density compared with conventional aviation fuels,” said the paper’s co-author Li Ning, a research scientist at the Dalian Institute of Chemical Physics of Chinese Academy of Sciences.
The utilization of high-density aviation fuel can significantly increase the range and payload of aircraft without changing the volume of oil in the tank, according to the study.
Cellulose, the main component in the biofuel, is a cheap, renewable, and highly abundant polymer that forms the cell walls of plants. While chain alkanes (such as branched octane, dodecane, and hexadecane) have previously been derived from cellulose for use in jet fuel, the researchers believe this is the first study to produce more complex polycycloalkane compounds that can be used as high-density aviation fuel.
Li’s team used wheatgrass cellulose in the lab to produce a mixture of C12 and C18 chemicals with a low freezing point and a density about 10 percent higher than that of conventional jet fuels. Li and his team found that cellulose can be selectively converted to 2,5-hexanedione using the chemical reaction hydrogenolysis. They then developed a method of separating the compound 2,5-hexanedione by converting the 5-methylfurfural in hydrogenolysis product to 2,5-hexanedione, while keeping 2,5-hexanedione in the product unchanged.
This resulted in a 71% isolated carbon yield — a 5% increase from the product yield in their initial work. Finally, they reacted hydrogen with the 2,5-hexanedione from wheatgrass cellulose to obtain the final product: a mixture of C12 and C18 polycycloalkanes with a low freezing point and a density about 10% higher than that of conventional jet fuels. Much of the biofuel’s potential lies in this high density — it can be used as either a wholesale replacement fuel or as an additive to improve the efficiency of other jet fuels.
It can be used as either a wholesale replacement fuel or as an additive to improve the efficiency of other jet fuels, according to the study.
“The aircraft using this fuel can fly farther and carry more than those using conventional jet fuel, which can decrease the carbon dioxide emissions during the taking off and landing,” said Li.
Although the researchers produced the biofuel at a laboratory scale in this study, Li and his team believe the process’ cheap, abundant cellulose feedstock, fewer production steps, and lower energy cost and consumption mean it will soon be ready for commercial use. They also predict it will yield higher profits than conventional aviation fuel production because it requires lower costs to produce a higher-density fuel.
The biggest issue holding the process back is its use of dichloromethane to break down cellulose into 2,5-hexanedione; the compound is traditionally used as a solvent in paint removers and is considered an environmental and health hazard.
“In the future, we will go on to explore the environmentally friendly and renewable organic solvent that can replace the dichloromethane used in the hydrogenolysis of cellulose to 2,5-hexanedione,” said Li. “At the same time, we will study the application of 2,5-hexanedione in the synthesis of other fuels and value-added chemicals.”
Source: Xinhua News, Science Daily, Cleantech Concepts.