Methanol Production Process
February 15, 2025
The methanol production process is a low-pressure process. Methanol is produced using natural gas, gases from refinery processes, synthesis gas, coal, coke, or even biomass.
Industrially, methanol is synthesized from coal or natural gas. The reforming process in methanol production is carried out in various ways, including the following types of reforming used in this process:
- Steam Reforming
- Pressure Reforming
- Autothermal Reforming
- Combined Reforming
- Hot Gas Reforming
After the reforming process, stages such as compression and methanol synthesis are carried out. Crude methanol is separated from water, ethanol, and other compounds in the separation unit. These impurities are separated in a system that includes two distillation columns. In the first column, light impurities such as ethers, esters, acetone, and insoluble gases are removed. In the second column, water, heavier alcohols, and similar heavy organic materials are removed from the stream.
To neutralize acidic gases, potassium hydroxide (KOH) is used in this process. Additionally, to adjust pH and improve the system’s resistance to corrosion, morpholine is used in the methanol production process. Today, except for China, which uses coal as feedstock for methanol production, other regions of the world use cheap natural gas as feedstock for methanol production.
From an economic perspective, the choice between synthesis gas technology and coal for methanol production can vary. In China, due to the vast coal resources, the construction of units based on this technique is prioritized. Additionally, globally, there is a tendency to use offshore units due to access to cheaper gas reserves, utilizing oil extraction facilities for methanol production from natural gas. There are various methods for preparing and synthesizing methanol from natural gas, including:
- Steam Reforming
- Partial Oxidation
- Catalytic Partial Oxidation
- Photochemical
- Photocatalytic
To convert natural gas to methanol, two methods are used:
direct and
indirect. In the direct method,
synthesis reaction is absent, and methane is directly converted to methanol at high temperature and pressure. Due to the special operating conditions (high temperature and pressure), the use of this method in the industry is limited.
The indirect method is carried out in three stages. In the first stage, methane reacts with water to produce carbon monoxide and hydrogen, which is called synthesis gas production. Due to the importance of this stage and its highly endothermic nature, requiring a lot of energy, about 60% of the total process cost is related to this stage.
In the second stage, the synthesis gas produced in the first stage is converted to methanol. After methanol production, in the third stage, methanol is separated from the system, and unconverted gases are returned to the system for methanol production again.
Modern Methanol Production
Methanol is one of the widely used and fundamental chemical products that can be produced using collected and stored carbon dioxide. The petroroot methanol production unit is one of the important petrochemical units.
So far, 5 methanol units with a production capacity of 5 million tons per year have been established, and about 12 units with a capacity of 19 million tons per year are under review and commissioning. The main reason for focusing on methanol production with recovered carbon dioxide is the production of methanol from any source of carbon dioxide.
This advantage allows the use of any source of produced carbon dioxide, a greenhouse gas, to be used and entered into the recovery cycle. In this cycle, carbon dioxide is collected from any source and converted into methanol by reacting with hydrogen, and then recovered. In this cycle, the required hydrogen is completely independent of fossil fuels and is produced using electrolysis.
In this cycle, methanol is renewable in such a way that in other processes, using methanol, petroleum compounds such as ethylene, propylene, gasoline, and other products that are derivatives of oil and gas are produced. Upon combustion of these products, carbon dioxide is produced again and released into the air, which is then recovered and collected and sent back to the methanol production cycle. Converting carbon dioxide into organic compounds and preparing fuels is one of the most useful methods for reducing carbon dioxide.
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