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Technological advancements in methanol production processes: The liquid-phase methanol synthesis process offers both technical and economic advantages, and it is set to compete with the gas-phase synthesis process on an industrial scale in the near future. CO2 hydrogenation to methanol and direct methane synthesis to methanol are key development technologies in the methanol industry. In recent years, the gas-liquid synthesis method has attracted attention. Since methanol synthesis is an exothermic reaction, thermodynamically lower temperatures are favorable for the reaction to proceed. If a catalyst with high activity at low temperatures can be found, along with a means to remove the heat of reaction promptly, the one-pass conversion rate of CO can be significantly increased. Metal salts such as nickel acetate, palladium acetate, cobalt acetate, as well as ruthenium and rhenium in low-temperature and low-pressure catalysts have attracted attention from various circles and represent a new focus in methanol synthesis research. (1) The dual-methane process used by the Linqi branch of Shanxi Fengxi Fertilizer Company is worth emulating; they utilize CO, CO2, and H2 in the raw gas to produce crude methanol under the action of a catalyst at a certain temperature. This process is similar to the hydroxylamine production in the ammonia synthesis process, but it has higher requirements for the parameters of the gas after alcohol formation; unlike in hydroxylamine production, where the level of this gas can be controlled by adjusting the circulation volume of the copper solution. Therefore, the design of the alcohol tower requires higher conversion efficiency and better heat utilization; such towers are relatively large in size and have a low production load, allowing them to operate without maintenance for 4 to 5 years after initial commissioning. (2) The traditional methanol process involves the gas-phase reaction of CO and H2 using a Cu-Zn-Al catalyst at temperatures of 250–350°C and pressures of 5–15 MPa; the one-pass conversion rate is only 15%~20%. Product gas recycling or the use of series reactors is required to increase yield, and large compressors are necessary. In recent years, efforts have been made to explore routes that replace homogeneous catalysts for the liquid-phase synthesis of methanase, but no success has been achieved on an industrial scale. Not long ago, the Tokyo Institute of Technology in Japan developed a new solid-phase catalyst that can produce methanol with high conversion efficiency in one step during liquid-phase reactions. The specialized catalyst is a combination of a thermally stable anion exchange resin (with methoxy functional groups) and a copper catalyst. During the reaction, H2 and CO pass through a methanol slurry containing this multiphase catalyst at temperatures of around 100–150°C and pressures of 5 Ma; CO reacts with methanol to form the intermediate methyl formate, which is then catalytically converted into 2 molecules of methanol. The one-way conversion efficiency can reach 70%. It is said that by increasing the Cu content in the catalyst, a one-time conversion rate of up to 98% can be achieved at 100–150°C and 5 MPa. However, this achievement is still in the stage of basic research, but the new catalyst represents a promising approach to reducing the costs and complexity of methanol synthesis. This catalyst is superior to some homogeneous catalysts because it can be easily separated from liquid products, and liquid-phase operation at low pressures also reduces the need for heat exchangers and compressors. (3) A new process for producing methanol from CO2 has been officially developed by the Nanotechnology Research Center at the Korea Institute of Science and Technology (KIST). A pilot plant with a capacity of 100 kg per day is now in operation; in this Camero process, through a reverse water-gas conversion reaction, CO2 reacts with H2 to form CO and H2O at temperatures of 600–700 °C and at atmospheric pressure, using a ZnAl2O4 catalyst. Before entering the methanol synthesis reactor, the product gas is first dried to remove H2O. In the methanol synthesis reaction, at 250–300°C and 5–8 MPa, a CuO/ZnO/ZrO2/Al2O3 catalyst is used to enable CO and unreacted H2 to combine to form methanol. (4) To overcome the drawbacks of traditional methanol synthesis processes, such as low single-pass conversion rates, high recycle ratios, and high energy consumption, Nippon Toyoe Engineering Corporation and Mitsui East Asia Chemical Company jointly developed a new type of energy-saving and consumption-reducing multi-stage internally cooled radial-flow methanol synthesis tower. With a production capacity of 2500 t/d, a diameter of 4700 mm, a height of 14100 mm, and a weight of 420 t, it features a pressure drop of 0.05 Ma; 2.5 GJ of heat can be recovered per ton of methanol produced. After the demonstration unit was built, during the retrofit of a 1200 t/d methanol plant in Trinidad and Tobago, a synthesis tower was installed parallel to the existing ICI cold tower, achieving the desired results entirely. This synthesis tower has been introduced into the 600,000 tons per year methanol plant of Hainan Offshore Oil Fudao Chemical Company in our country. The advantages of this new type of methanol synthesis tower are: (a) low gas pressure drop, with the pressure drop being only 1/10 that of conventional axial towers; (b) high heat recovery; (c) effective temperature control, resulting in high methanol production efficiency, with the methanol concentration at the outlet of the synthesis tower exceeding 8.5%; (d) long catalyst life; (e) high production capacity. (e) It offers significant energy-saving effects; by reducing the pressure drop within the tower and the gas circulation speed, power consumption is reduced by 50%, thereby saving a large amount of energy. The thermal energy consumption for methanol synthesis in this cycle system decreases from 111.6 MJ to 57.0 MJ. (5) Innovative technologies for producing methanol via coal gasification coupled with the synthesis of ammonia and urea have been developed. Producing methanol through pressurized gasification with pure oxygen, and utilizing the methanol off-gases to produce ammonia and urea, represents one of the most effective ways to make comprehensive use of coal by converting it into clean energy sources and fertilizer products. It is a new ammonia-methanol production process that features energy savings, reduced consumption, recycling, and environmental protection. In this process, the CO+H2 synthesis gas used for ammonia and methanol production is derived from the conversion of coal or hydrocarbons. Due to the gasification temperature of 1400–1700°C, the coal utilization rate can reach 99%, with only 0.3% CH4 in the gas, while the yield of CO + H exceeds 90%. Per ton of ammonia, 282 m3 of off-gas is generated during the synthesis process, which is then converted into ammonia and urea. At present, many places such as Sichuan, Shanxi, Inner Mongolia, Heilongjiang, and Ningxia are building such devices, and this technology is showing good development momentum. (6) A new process for the liquid-phase synthesis of methanol, an efficient method, has recently been developed with success by Air Products Liquid Phase Conversion, a company established through a partnership between Air Products and Chemicals and Eastman Chemical Company. This process achieves zero waste emissions and can produce high-purity methanol products. Unlike traditional processes, this LPMEOH process uses a slurry bubble column reactor (SBCR) designed by Air Products; when syngas enters the SBCR, the powder catalyst is dispersed in inert mineral oil, and under the action of this catalyst, methanol is produced from the syngas. The LPMOH process can handle feed gas of different concentrations derived from gasification; it is capable of absorbing 25%-50% of the calorific value in syngas, and it does not require the process steps used in traditional technologies to remove CO2 from the feed gas, allowing for the production of methanol with a purity of 99%. (7) The Advanced Technology Program (ATP) of the U.S. Department of Commerce funded UOP to develop a technology for producing methanol from methane in liquid phase; between 2005 and 2007, this project cost $5 million, of which ATP provided $2 million in funding. The project will focus on the development of low-temperature methane processes. UOP said that if the project is successful, it will proceed immediately to industrial production. It is estimated that this technology can reduce the production cost of methanol from $80 per ton to $58 per ton. In addition, investment costs, energy consumption, and CO2 emissions as a by-product will decrease by 50%, 60%, and 33%, respectively. It is said that this technology can be used to build plants using natural gas from remote areas.