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Methyl tert-butyl ether (abbreviated as MTBE), also known as 2-methoxy-2-methylpropane, has the structural formula CH3OC(CH3)3; its molecular formula is C5H12O, and its molecular weight is 88.15. MTBE was first synthesized in 1904, and its properties were characterized. During World War II, research in the United States confirmed the role of MTBE as a high-octane additive for gasoline. Internationally, the production process for MTBE was developed in the late 1950s and early 1960s. From the 1960s to the 1970s, medium-scale tests were conducted to develop industrial production processes and engineering techniques for MTBE; at the same time, tests were carried out on using MTBE as a high-octane additive for gasoline, and efforts were made to produce pure isobutylene through the cracking of MTBE. The world’s first set of MTBE industrial plants came online in Italy in 1971. In December 1979, the first set of MTBE industrial plants in the United States came online. Since the mid-1970s, to protect the environment and reduce air pollution caused by the use of tetraethyl lead-containing gasoline in cars, the United States has successively implemented measures to restrict and ban the addition of tetraethyl lead to gasoline. To meet the requirement of increasing gasoline octane rating, the U.S. Environmental Protection Agency officially approved the use of MTBE as an additive in lead-free gasoline in 1979. The Clean Air Act amendments enacted in the United States in 1990 stipulate that the vapor pressure and aromatic content of gasoline should be reduced, and oxidizing compounds should be added to gasoline in order to decrease CO, NOX, and volatile organic compounds in vehicle exhaust emissions ； In areas where CO emissions exceed the specified limits, a program for using oxygenated gasoline shall be implemented, with the minimum molar fraction of oxygen in the gasoline being no less than 2.7% ； In areas with severe ozone pollution, new-formula gasoline with a minimum oxygen content of 2.0% is used year-round. In 1979, the United States used 16 kt of MTBE; in 1980 it was 278 kt, in 1985 it rose to 1,395 kt, in 1990 to 3,945 kt, and in 1995 to 9,927 kt. Western Europe began using MTBE as an additive to increase the octane rating of gasoline in 1973. In other regions, plans to limit lead in gasoline, ban its use, and introduce MTBE as an additive were gradually implemented starting from the 1980s. In 1985, the world’s MTBE production capacity was 2,449 kt, with isobutylene, the raw material used for its production, coming from ethylene plants at 66%, refineries at 23%, and tert-butanol at 11%. In 1994, the world’s MTBE production capacity was 19,853 kt. The sources of isobutylene, the raw material used for its production, were as follows: 34% from oil field butanes, 28% from refineries, 20% from ethylene plants, and 18% from tert-butanol. If all the MTBE plants that are currently in operation, under construction, or in the design phase and use oil field butane as a raw material are included, the capacity of these plants to produce MTBE from oil field butane accounts for about 50% of the world’s current MTBE production capacity. The United States is the country that produces and consumes the most MTBE in the world. The United States has the highest refining capacity, ethylene production capacity, and petrochemical product production capacity in the world. It also possesses abundant oil field gas resources, which is why the source of isobutylene, the raw material used for producing MTBE in the U.S., differs from that in other countries. In the early 1990s, isobutylene from refineries and ethylene plants accounted for about 33%, isobutylene derived from tert-butanol accounted for about 51%, and isobutylene obtained from oil field gas accounted for about 16%. As an additive for motor gasoline with high octane rating, MTBE has played a positive role in the lead-free transformation of domestic motor gasoline, the improvement of gasoline quality, as well as the production and export of cleaner gasoline. It has become an essential blending component for lead-free gasoline in our country, especially high-octane gasoline. Relying on its own scientific and technological capabilities, our country has successfully developed various types of MTBE synthesis processes, with a technical level that is on par with that of foreign countries. The industrial use of MTBE has made due contributions to the development of China’s refining and petrochemical industries as well as to environmental protection. The development of MTBE technology in China started relatively late; at the end of the 1970s, more than a dozen organizations began conducting research on it. In the early 1980s, organized development of MTBE production technology took place in the country. In 1984, the rubber plant of Qilu Petrochemical Company built China’s first MTBE production facility with an annual capacity of 5,500 tons. With the close cooperation of relevant parties, a series of MTBE production technologies have been developed successively. The Research Institute of Qilu Petrochemical Company, Beijing Design Institute and other organizations have jointly developed tube reactor technology, cylindrical external circulation reactor technology, mixed-phase reaction technology, catalytic distillation technology, and mixed-phase reactive distillation technology. Luoyang Engineering Company developed the expanded bed reaction technology, while Jilin Chemical Industry Company developed the tubular external circulation reaction technology. By 2006, more than 60 sets of MTBE plants had been built in China using domestically developed technology, with a total production capacity exceeding 2.5 million tons per year.