The pyrolysis process , also called the pyrolytic process, is a thermal decomposition technique that occurs in the absence of oxygen, that is, in a completely dry atmosphere. In this process, biomass is degraded, forming solid, liquid, and gaseous products, including charcoal, oils, and gases such as methane and hydrogen. This technique can occur naturally or be induced and has a wide range of industrial and environmental applications.
In this article, we will explore further the characteristics of pyrolysis, its types, both industrial and domestic applications, and the benefits in terms of sustainability.
Key features
Pyrolysis is a thermochemical process that can be applied to any carbon-rich organic material . It is carried out by heating the material to high temperatures, in the absence of oxygen, to decompose it into different molecules. This process is a form of thermolysis and is the precursor to systems such as gasification or complete combustion.
One of the main characteristics of pyrolysis is that, when the material decomposes completely, only carbon remains in its structure, a process known as carbonization . The products resulting from pyrolysis include gases such as methane and carbon dioxide; liquids, mostly oils and tars; and solids such as charcoal.
This process has many useful applications, from the energy sector to the chemical industry. Depending on the conditions, such as the temperature used, different products are obtained that can be used in various industrial applications.
Types of pyrolysis
There are several types of pyrolysis that vary depending on the physical conditions and the technique used to carry out the process. The main types are:
- Aqueous pyrolysis: It occurs when a small amount of water is used in the process. It is used, for example, in the cracking of heavy crude oils or in the depolymerization of organic waste.
- Vacuum Pyrolysis: In this type of pyrolysis, the material is heated in a vacuum environment to reduce its boiling point and prevent unwanted reactions. It is mainly used in industries that require purer materials.
- Fast pyrolysis: also known as fast pyrolysis. It is a process that seeks the rapid decomposition of biomass into oil, gas and coal by raising the temperature to about 500 °C.
- Slow pyrolysis: Often used for charcoal production, the material is heated to moderate temperature levels for extended periods of time.
The pyrolysis process has several stages:
- First, there is a slow decomposition, with the formation of water and gases such as carbon dioxide and hydrogen.
- As the temperature increases, the stage of active decomposition, characterized by the production of hydrocarbons and tars.
- In the final phase, at more than 600 °C, the remaining hydrogens are eliminated, leaving a majority carbon residue.
Depending on the objectives, one or another type of pyrolysis can be used to obtain products with higher added value, such as biochar or syngas (synthesis gas).
Applications of pyrolysis in cooking
In the home, one of the best-known uses of pyrolysis is in pyrolytic ovens . These devices have a specific self-cleaning function that uses the principle of pyrolysis to incinerate food residue inside. By raising the temperature to around 500°C, the heat decomposes organic matter into water vapor and carbon dioxide, and inorganic matter into ash. This function is ideal for keeping the oven clean without the use of chemicals.
The process usually takes between one and four hours, depending on the level of dirt. Once finished, you only need to remove the ashes with a damp cloth. In addition to keeping the oven clean in a simple way, this system is environmentally friendly and avoids the use of polluting products.
They are safer than traditional ovens, as they have automatic locks when they reach 500°C to prevent accidents. They also help save time and energy, as they can be programmed to operate during times when electricity costs are lower.
Benefits and environmental applications of pyrolysis
One of the main benefits of pyrolysis is its ability to reduce pollution . Because it doesn't require oxygen, the amount of emissions is much lower compared to other techniques like incineration. This helps manage waste that would otherwise be incinerated or landfilled. Furthermore, by processing industrial waste or biomass, energy is generated in the form of biofuels or biogas, thus helping to diversify renewable energy sources.
In industrial applications, pyrolysis is used to transform waste plastics, tires, and biomass into valuable products such as fuels or synthesis gas. The biochar generated is useful as a soil amendment in agriculture, and the gas produced can be reused in other processes, transforming waste into efficient energy solutions.
Another interesting aspect is that, as it is a controlled process, there is the possibility of applying pyrolysis in the valorisation of hazardous waste, facilitating its destruction without releasing toxic gases into the environment. Likewise, it can be used to generate synthesis gas which is later converted into usable energy.
In short, pyrolysis is not only an effective tool for waste management, but also promotes the creation of reusable materials and renewable energy in an efficient manner. Thanks to its application in various industrial and domestic sectors, it has become one of the most promising techniques for global sustainability.