Biomass energy is the energy that solar energy is stored in biomass in the form of chemical energy, that is, energy using biomass as a carrier. It is directly or indirectly derived from the photosynthesis of green plants, and is the only carbon resource that can replace fossil energy into gaseous, liquid and solid fuels and other chemical raw materials or products. Biomass energy is extremely rich as a clean and renewable energy source. It is estimated that the carbon fixed by photosynthesis in the world is 2×1011 tons per year, and the energy content is 3×1018 kilojoules. It is equivalent to about 10 times the world’s annual energy consumption; the available dry biomass is about 170 billion tons. However, currently only 1.3 billion tons of it are used as energy, accounting for about 0.76% of its total output. The development and utilization potential are huge.

  Bio-jet fuel is aviation kerosene produced by using animal and vegetable fats and oils as raw materials and using catalytic hydrogenation and other technologies. When it comes to bio-jet fuel, biodiesel has to be said. Although in the 1980s, American scientists proposed the concept of biodiesel and conducted a lot of research on it, compositing the first generation of biodiesel represented by fatty acid methyl esters. However, its oxygen content is too high, and the calorific value is relatively low, and the chemical structure of its components is obviously different from that of diesel. Thus, the first generation of biodiesel has not been widely used. Due to the shortcomings of the first-generation biodiesel in the use process, in recent years, researchers have proposed that the first-generation biodiesel be subjected to hydrodeoxygenation, isomerization and other reactions to obtain alkanes similar to diesel components, forming the second-generation biodiesel preparation technology. The second-generation biodiesel has the same chemical structure as diesel, and the viscosity and calorific value are similar to diesel, and has the advantages of a lower density , higher cetane number, lower sulfur content, lower pour point, and the oxidation stability equivalent to diesel. It can be added to diesel in a larger proportion. Bio-jet fuel is mainly composed of C9 ~ C16 straight chain alkanes, whose composition is similar to conventional petroleum-based jet fuel, and has good low-temperature engine starting performance and lubricity. Compared with traditional jet fuel, bio-jet fuel can reduce carbon dioxide emissions by 55-92%. Its composition and structure are similar to petroleum-based aviation jet fuel. It can meet the power performance and safety requirements of aircraft. It does not need to replace the engine and fuel system, and has high environmental advantages. The development of bio-jet fuel has been recognized as the fundamental way for the aviation industry to achieve carbon reduction targets.

  The production process of bio-jet fuel mainly includes the following three types: Fischer-Tropsch synthesis, hydrodeoxygenation, and rapid pyrolysis. (1) Fischer-Tropsch synthesis refers to the conversion of biomass to synthesis gas (the main components are H2 and CO) through a thermochemical process under high temperature and high pressure. The synthesis gas generates various hydrocarbons and oxygen-containing organic compounds through the Fischer-Tropsch synthesis process. The resulting product can be made into biological jet coal by further hydrodeoxygenation treatment. (2) Hydrodeoxygenation refers to the deep hydrogenation of vegetable fats or animal fats to produce hydrodeoxygenated oil. In order to make the produced hydrodeoxygenated oil meet the requirement of directly blending with petroleum-based fuel, the hydrodeoxygenated oil needs to further increase molecular branching through hydroisomerization reaction. (3) Rapid pyrolysis refers to the thermochemical process in which biomass is rapidly decomposed by heat under anaerobic or anoxic conditions, eventually producing charcoal, bio-oil and non-condensable gas. Rapid pyrolysis technology is usually combined with catalytic technology to further hydrodeoxygenate the product. In summary, the three main production processes of bio-jet fuel will involve catalytic hydrodeoxygenation reaction; we choose hydrodeoxygenation/hydrohydroisomerization process to study the conversion of castor oil to bio-jet fuel.