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METHANOL Climate change and the unattainability of fossil fuels are calling for cleaner energies such as methanol as fuel. Methanol is one of the simplest molecules for energy storage and is utilized to generate a whole range of products such as plastics, formaldehyde, acetic acid, hydrocarbons (gasoline and olefins). Methanol production is based on the chemical process, which converts natural gas (CH4, methane) into methanol by three key stages: steam reforming, synthesis, and distillation. Steam reforming is the first step, where methane reacts with steam in the presence of a catalyst (typically nickel) at high temperatures (700–1,000°C) to produce syngas, a mixture of hydrogen (H₂), carbon monoxide (CO), and carbon dioxide (CO₂). The syngas is then passed through a reactor containing a catalyst (often copper-based) under moderate pressure (50–100 bar) where, CO and CO₂ react with H₂ to form methanol and water. This is the synthesis stage. Finally, the distillation stage where the crude methanol produced contains impurities like water and other byproducts. It undergoes distillation to purify it, resulting in high-purity methanol ready for industrial use. Methanol may be created from carbon sources, such as coal, natural gas, byproduct streams, biomass, or carbon dioxide from different sources, such as direct air capture (DAC) and industrial flue gases. Fig 1 provides a simplified summary of the processes involved in synthesizing methanol. Nevertheless, for primarily economic reasons, methanol continues to be generated nearly entirely from fossil fuels. Grey methanol (methanol produced from natural gas) accounts for around 65% of methanol production, whereas coal gasification accounts for most of the remaining 35% (brown methanol). Approximately 1% of methanol global production originates from renewable sources (green methanol). Due to abundant resources, a low-price level which is subject to moderate volatilities, and low content of impurities, natural gas is the predominating feedstock for methanol production. This research project aims to design, simulate, and optimize a methanol production plant that uses natural gas as a raw material, examining the technical, economic and environmental aspect of this process. Figure 1: Processes involved in methanol synthesis. Natural gas (also fossil gas, methane gas, and gas) is a naturally occurring compound of gaseous hydrocarbons, primarily methane (95%) small amounts of higher alkanes, and traces of carbon dioxide and nitrogen, hydrogen sulfide and helium. Methane is a colorless and odorless gas, and, after carbon dioxide, is the second-greatest greenhouse gas that contributes to global climate change. HISTORY OF METHANOL Pure methanol, was first obtained in 1661 by Robert Boyle, who called it spirit of box, because he produced it via the distillation of boxwood. Mittasch and his coworkers prepared a methanol containing mixture from synthesis gas (CO+H2) with Fe catalyst in 1913 at BASF. In 1923, the German chemist Matthias Pier, working for BASF also, developed a highly selective catalytic reaction to convert synthesis gas (a mixture of carbon monoxide and hydrogen derived from coke and used as the source of hydrogen in synthetic ammonia production) into methanol. Pressure 25 – 35 MPa Temperatures of about 400°C. Catalyst ZnO/Cr2O3 on alumina. In 1966, ICI developed as first a route for methanol synthesis in which sulfur free synthesis gas (based on natural gas) containing a high proportion of carbon dioxide was reacted on highly selective copper oxide catalysts. Pressure 5-10 MPa Temperature between 200-300°C Methanol can now be produced much more economically worldwide by these low-pressure methods. (95%) The economic plant size is between 500 and 1000 kto/year. THE PROCESS TECHNIQUE The process technique for synthesizing methanol from natural gas is well evolved, and methane reforming is the major industrial method for producing methanol. Syngas, which is often produced by reforming (that is, the processes that rearrange or modify the molecular structure of hydrocarbons to improve their properties) natural gas, is the raw material used to make methanol. Conventionally, in order to convert the syngas to methanol, a catalyzed reaction using Cu–ZnO takes place in a fixed-bed reactor. The operational conditions are controlled in the range of Temperature =250–280 ◦C, and Pressure =60–100 bars. Utilizing a catalyst made of copper, zinc, and chromium enables the production of large amounts of methanol without the necessity of extremely high pressures. Fast reaction rates might be accomplished at reduced temperatures of 200–300 ◦C because of the lower pressures, which decreased the generation of byproducts. In another study a new nickel-gallium (Ni–Ga) catalyst capable of producing methanol at low pressures is introduced. At high temperatures and room pressure, nickel-gallium produced more methanol than the conventional Cu–ZnO catalyst, and considerably less of the carbon monoxide byproduct. Table 1: Compares the functionality of these two types of catalysts for methanol production. METHANOL PRODUCTION The stages of the methanol production process comprise;1. feed purification.2. reforming, syngas compression.3. methanol synthesis.4. distillation, recovery, and recycling.ReformingSteam reforming (SR) and auto- thermal reforming (ATR) are two primary technologies ofmethane reforming processes. The steam reforming (SR) process is endothermic and requires anexternal energy resource. Partial oxidation (POX) of methane followed by steam reformation maybe used in the ATR reactor to achieve thermal equilibrium. An energy balance is reached in thiscase because the former reaction (i.e. partial oxidation) produces heat that the endothermic steamreforming process will utilize.(Steam Reforming Reaction-SR) CH4 +H2O ↔ CO +3H2 ΔH◦298K =206 kJ/ mol(Partial Oxidation Reaction-POX) CH4 +1/2O2 ↔ CO +2H2 ΔH◦298K = 38 kJ/molTwo variants of steam reforming and auto-thermal reforming integration are two-step reforming(TSR) and combination reforming (CR). TSR employs a series connection of two reformers, oneof which is a steam reformer and the other is an auto-thermal reformer. While in the CR processsetup, the two reformers are linked sequentially and simultaneously. The steam reformer receivessome methane feed, and the auto-thermal reformer receives the remainder. The steam reformer’soutput is delivered to the auto-thermal reformer for a different reaction. The partial oxidation(POX) process is the most cost- effective and economical method for producing syngas appropriatefor methanol synthesis. Still, the combined reforming (CR) method results in minimum carbondioxide emissions.Much studies describes the industrial operating conditions of several reforming processesregarding methane reforming. Figure 2: Various Reforming ProcessesMethanol Synthesis and distillation Methane reforming is followed by methanol production and purification (distillation). The methanol purification system is based on the unit operation of distillation. The system includes two distillation stages. In the first ‘topping’ stage, the compounds more volatile than methanol, such as 𝐻2𝑆 and ammonia are removed in the vapor phase while the methanol, water and other less volatile compounds remain in the bottoms. In the second ‘rectification’ stage, the purified methanol is recovered from near the top of the column while the water and the other less volatile compounds are removed from the bottoms. The following reaction occurs during methanol synthesis: CO +2H2 ↔ CH3OH ΔH◦298K = 90.7 kJ/mol CO2 gas is usually mixed with input gas to compensate for carbon deficiencies. CO2 +3H2 ↔ CH3OH +H2O ΔH◦298K = 49.5 kJ/mol[caption id="attachment_9142" align="alignnone" width="300"] Figure 3: Summary Of The Processes Involved In Synthesizing Methanol.[/caption] METHANOL PRODUCTION TECHNOLOGIES (EQUIPMENT) From an economic point of view, the highest sensitivity of the overall cost of a methanol plant is related to the reforming section, accounting for more than 60% of the capital investment. Catalytic steam reforming of methane (SR) is the most widely used technology for syngas generation in methanol plants, while the implementation of alternative technologies such as autothermal (ATR), dry methane reforming (DMR) and gas heated reforming (GHR) has started in the last decade. CONCLUSION Currently, only less than 0.2 million tons of renewable methanol is generated per year. Both pathways result in methanol chemically identical to methanol produced from fossil fuels. The requirement to mitigate climate change by drastically decreasing or avoiding 𝐶𝑂2 emissions is driving attention to renewable methanol. Methanol as an adaptable fuel can be utilized in fuel cell cars, hybrid cars, IC engines, and various types of vessels. Storage, transportation, and distribution are all made easy because it is in liquid form at standard room pressure and temperature. It may be combined with conventional fuels and is compatible with the current distribution infrastructure. Experimental methods are not required to produce methanol from biomass and 𝐶𝑂2, and 𝐻2 . Syngas derived from fossil fuels is utilized to make methanol, and bio- and e-methanol may be produced with almost comparable, commercially viable technology. REFERENCES 1. Bertau M, Offermanns H, Plass L, Schmidt F. Methanol: the basic chemical and energy feedstock of the future. Heidelberg: Springer Berlin; 2014. Edition 2. Meyer Steinberg. Production of hydrogen and methanol from natural gas with reduced CO2 emission. Int J Hydrogen Energy 1998;23(6):419–25. 3. Lee Boreum, Lee Hyunjun, Lim Dongjun, et al. Renewable methanol synthesis from renewable H2 and captured CO2: how can power-to-liquid technology be economically feasible? Appl Energy 2020;279:115827. 4. Leonzio Grazia. State of art and perspectives about the production of methanol, dimethyl ether and syngas by carbon dioxide hydrogenation. J CO2 Util 2018;27: 326–54. 5. Blumberg Timo, George Tsatsaronis, Morosuk Tatiana. On the economics of methanol production from natural gas. Fuel 2019;256:115824. 6. Kim Aasberg-Petersen, Nielsen Charlotte Stub, Dybkjær Ib, Perregaard Jens. Large scale methanol production from natural gas. Haldor Tapsoe; 2008. 7. TriLuu Minh, Milani Dia, Bahadori Alireza, Ali Abbas. A comparative study of CO utilization in methanol synthesis with various syngas production technologies. J CO2 Util 2015;12:62–76.8. Khalafalla Siddig S, Umer Zahid, Abdul Gani Abdul Jameel, Ahmed Usama, Alenazey Feraih S, Lee Chul-Jin. Conceptual design development of coal-to- methanol process with carbon capture and utilization. Energies 2020;13(23): 6421. 9. Bermúdez JM, Fidalgo B, Arenillas A, Men´endez JA. Dry reforming of coke oven gases over activated carbon to produce syngas for methanol synthesis. Fuel 2010; 89(10):2897–902. FELICITY MAAME YAA SERWAA OSEI

Nana Kwadwo Otieku-Boadu

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