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How to make oil at 200 degrees C? Revealing the two-stage process of a 1939 US patent!
With today's demand for renewable energy, how to effectively convert biomass into usable fuel has become a hot research topic. Hydrothermal liquefaction (HTL) is a pyrolysis process that can convert wet biomass into crude oil-like products, which is particularly important in times of energy crisis. In 1939, U.S. Patent 2,177,557 described a two-stage process that might hold the key to turning biomass into oil.
This process demonstrates how water and high pressure can accelerate the efficiency of converting organic matter, providing a possible solution for a clean energy future.
Basic concepts of hydrothermal liquefaction
Hydrothermal liquefaction is a pyrolysis process carried out at high pressure and moderate temperature to convert biomass into high energy density crude oil through thermochemical conversion. Its working principle is to use the supercritical or subcritical state of water to promote the conversion of biomass. The oil produced contains a calorific value of up to 33.8-36.9 megajoules per kilogram, and has low viscosity and high solubility, which can be used as a transport The fuel may be further upgraded to diesel, gasoline and other fuels.
The two-stage process in 1939
In 1939, with the advent of a U.S. patent, the basic concept of hydrothermal liquefaction began to take shape. The process described in the patent involves two main stages: the first stage is to heat a mixture of water, wood chips and calcium hydroxide at a temperature ranging from 220 to 360 degrees Celsius and a pressure higher than the saturated water vapor pressure. The main purpose of this process is to produce "oil and alcohol". The second stage involves "dry distillation" to produce various "oils and ketones," but the specific temperature and pressure conditions were not disclosed.
This two-stage process laid the foundation for future hydrothermal liquefaction technology and sparked subsequent research interest during the oil embargo of the 1970s.
History of hydrothermal liquefaction
The idea of producing oil from biomass using hot water and alkaline catalysts has been around since the 1920s. With the oil crisis in the 1970s, many research institutions began to explore this area. The Alberta Energy Research Centre and other institutions such as Shell Oil have also shown strong technical interest.
The process of chemical reaction
During the hydrothermal liquefaction process, long carbon chain molecules undergo thermal cracking reactions and remove oxygen elements through dehydration and decarboxylation reactions, ultimately forming bio-oil with a high hydrogen-to-carbon ratio. Such chemical reactions depend not only on temperature and pressure, but also on the composition of raw materials, reaction time and the use of catalysts.
Environmental impact and energy return
Biofuels produced through hydrothermal liquefaction are carbon neutral, meaning that they do not contribute significant carbon emissions to the environment when burned. This is much lower than the carbon emissions from traditional fossil fuels. Additionally, the process produces no harmful byproducts, making it a relatively clean energy option.
Conclusion and Future Challenges
The development of hydrothermal liquefaction technology represents a sustainable path for energy production and may have a profound impact on the future energy configuration. However, whether it can be commercialized on a large scale is a major challenge facing science, technology, economy and policy. Will current technology be able to meet our future energy needs?
