Selection of process routes for methanol to olefins

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The selection of process routes for methanol-to-olefins: The representative methanol-to-olefins technologies include the UOP/HydroMTO technology, the DMTO technology developed by Dalian Institute of Chemical Physics, and the Lurgi MTP technology. At present, these three process technologies are ready for industrial production. I. Technical Requirements 1. Characteristics of the MTO technology: Use of fluidized bed reactors and regenerators for continuous and stable operation ； A proprietary catalyst is used, and the catalyst needs to be regenerated online to maintain its activity ； The conversion rate of methanol reaches 100%, and the selectivity for low-carbon olefins exceeds 85%; the main products are ethylene and propylene ； The ratio of ethylene to propylene can be adjusted flexibly ； Ethylene and propylene reach polymerization levels. 2. The technical characteristics of the MTP process involve the use of a fixed-bed reactor to produce propylene from methanol; first, methanol is converted into dimethyl ether and water, and then it is transformed into propylene in three MTP reactors. The catalyst system uses an improved ZSM-5 catalyst developed by Southern Chemical, which exhibits high propylene selectivity. The conversion rates of both methanol and DME are greater than 99%, while the yield of propylene is approximately 71%. In addition to propylene, the product will also contain liquefied petroleum gas, gasoline, and water. Technically, MTO and MTP technologies are already mature and viable, meeting the conditions for industrial-scale deployment. II. Current status of industrial application: The large-scale coal-to-olefins projects under construction in China currently make use of various technologies. The main projects include the following: 1. In the Shenhua Group’s Baotou coal-to-olefins project, the methanol-to-olefins technology employed is the DMTO technology based on domestic independent intellectual property rights. The project was approved by the **Development and Reform Commission in December 2006, and its construction site is located in Baotou City, Inner Mongolia Autonomous Region. The construction scale includes: 1.8 million tons per year of coal-to-methanol production, 600,000 tons per year of methanol-to-olefins production, 300,000 tons per year of polyethylene production, 300,000 tons per year of polypropylene production; 4 oxygen production units with a capacity of 60,000 cubic meters per hour each; 3 thermal power plants with an evaporation capacity of 480 tons per hour each; as well as auxiliary production facilities and utility systems. Other major process units employ world-leading coal chemical/petrochemical technologies, including GE’s water-coal slurry gasification technology, Linde’s low-temperature methanol washing technology from Germany, DAVY’s methanol synthesis technology from the UK, DOW’s polypropylene technology from the US, and UNIVATION’s polyethylene technology from the US. Completion of the machinery is planned for the end of 2009, with operation to begin in 2010. 2. Projects that utilize the Lurgi MTP technology include the Shenhua Ningmei coal-to-olefins project and the Datang International Dolun coal-to-olefins project. The Shenhua Ningmei coal-to-olefins project began construction at the end of 2005; it is a key project within the plan for the development of the coal chemical industry in the Ningdong Energy and Chemical Industry Base in Ningxia. Upon completion, it will be able to produce 1.67 million tons of the intermediate product methanol per year, as well as 500,000 tons of the final product polypropylene. Additionally, 184,800 tons of gasoline and 41,200 tons of liquid fuel will be generated as by-products. The main process technologies include Siemens’ GSP dry coal powder gasification process from Germany, Lurgi’s low-temperature methanol washing process, methanol synthesis process, and MTP process from Germany, as well as ABB’s gas-phase polypropylene process from Germany. The project is expected to be completed in 2009. The Datang International Dolun Coal-to-Olefins Project has a total construction scale of 1.38 million tons per year of coal-based olefins (with 5 million tons of methanol as an intermediate product). The first-phase project has an annual production capacity of 460,000 tons of coal-based olefins (along with 1.68 million tons of methanol as an intermediate product), and it is located in Dolun County, Xilin Gol League, Inner Mongolia. It primarily employs a range of production technologies such as Shell powder gasification, Lurgi low-pressure methanol synthesis, Lurgi MTP propylene production process, and Spheripol polypropylene production process, with completion expected in 2009. III. Economic Comparison Based on the investment costs, final product profiles, and current market prices of the Shenhua MTO coal-to-olefins project and the Datang MTP coal-to-olefins project, a comparative analysis is conducted using 1.8 million tons of methanol as the basis; see Table 4-1. Table 4-1: Economic Comparison of 1.8 Million Tons of Methanol-Based Olefins Production Process Technology Total Investment (100 million yuan) Final Products Production Capacity (10,000 tons/year) Average Price (yuan/ton) Total Sales Revenue (10,000 yuan/year) MTO 116 Polyethylene 30 10,000 647,000 Polypropylene 30 9,900 Butene/C5 10 5,000 MTP 120 Polypropylene 49 9,900 592,140 Gasoline 14 6,000 Liquefied Petroleum Gas 7.2 3,200 IV. Selection of Process Technology In terms of final products, the MTP process produces polypropylene, along with gasoline and liquefied petroleum gas as by-products; however, the added value of these by-products is not high. The MTO products are polyethylene and polypropylene, and the proportion of these products can be adjusted according to market conditions, offering good market flexibility. In MTO technology, the domestic DMTO technology is essentially similar in terms of process to UOP/Hydro MTO technology; however, DMTO technology offers economic advantages in terms of patent fees and catalyst costs, and it is set to be successfully applied in large-scale olefin projects under construction in China. It is recommended to choose the methanol-to-olefins process by taking into comprehensive consideration the application of large-scale production of this technology, the product market positioning, and the investment in proprietary technologies.