The Facts About MMT
I. What is MMT?
1. MMT is the only antiknock additive allowed to be added under China's current national gasoline standard (GB17930-2006). It is mainly used by oil refining enterprises to increase the octane number of gasoline, make up for the deficiency of the octane number of base gasoline, and meet the market supply of high-grade gasoline.
2. The use of MMT reduces or lessens the degree of refining of gasoline by refineries. It not only benefits the comprehensive utilization of petroleum resources, but also benefits the energy saving and emission reduction of refining enterprises. It is an effective means of developing a low-carbon economy and is in line with the national energy industry policy.
Since the gasoline antiknock agent MMT was introduced into China in 1997, it has been widely used in refining enterprises, providing a positive factor for the improvement of gasoline quality and serving as an effective means for refineries to increase the production of high-grade gasoline. The use of MMT increases the flexibility of refineries in optimizing blending and helps refineries save energy and reduce consumption. In recent years, petrochemical enterprises have continuously increased the amount of MMT used, and the proportion of high-grade gasoline has risen year by year, ensuring market supply. Summary of the analysis:
In 2010, Chinese refineries used approximately 3,000 tons of MMT, increasing the output of No. 93 gasoline by more than 12 million tons and No. 97 gasoline by more than 7 million tons. In addition, blenders may have used about 300 tons of MMT.
By using 3,000 tons of MMT, refineries saved 700,000 tons of fuel oil and reduced CO2 emissions by 2 million tons.
Most importantly, it ensured market supply.
3. Does MMT have negative effects on vehicles?
MMT has passed a series of the most stringent tests in the history of fuel additives, including road tests of nearly 130 vehicles and thousands of tests covering engines, environmental impact, human health, manganese emission analysis, exposure models, and exhaust catalytic converters. After questioning from all sectors of society, on July 11, 1995, the U.S. Environmental Protection Agency finally approved the use of MMT in unleaded gasoline, confirming that MMT has no negative effects on vehicle exhaust purification systems.
4. The automobile industry opposes MMT. The automobile industry has always regarded additives in gasoline as uncertain variables. To ensure minimal risk to vehicles during the warranty period, automakers oppose adding any antiknock agent to gasoline, strictly restrict the olefins and aromatics that constitute the basic substances of gasoline, and hope that gasoline will be as purely "natural" as possible.
5. The debate over MMT
The most important information is that the EU imposed no restrictions on the use of MMT during the implementation of the Euro IV emission standards from 2005 to 2009, and imposed no restrictions on the use of MMT when the Euro V emission standards were implemented in 2010 either. However, under lobbying by the automobile industry, the EU began to limit the use of MMT to 6 mg Mn/L in 2011 without a scientific assessment, while at the same time requiring the relevant technical departments to conduct a technical assessment of metal additives before the end of 2012.
MMT has been used in China for more than 10 years. As of the end of 2010, more than 15 million vehicles with National IV technology had entered the market, using National II/III fuel, and no problem of exhaust catalytic converter blockage in in-use vehicles has been found. Automakers have indeed been unable to collect evidence of catalytic converter blockage in in-use vehicles.
The debate between automakers and MMT manufacturers over MMT has lasted more than 30 years, with each side having its own technical arguments. In essence, when automakers conducted durability tests of new models using commercial gasoline containing MMT, they found that the back pressure of the exhaust catalytic converter increased and exhaust emissions tended to deteriorate. The American company Afton has also conducted many large-scale road tests and found no blockage of the exhaust catalytic converter. The difference between the two sides' tests is that the automakers' tests are too severe: the driving mode is characterized by the entire test being carried out on a high-speed oval test track or on a bench/rig, with vehicles running continuously for more than a thousand kilometers without a single complete cold start. It is inappropriate to use this kind of driving mode, which is meant to assess the durability of vehicle parts, to assess MMT. Afton's road tests included highways and city roads, so the test results of the two sides differ. The severity of Afton's road tests is greater than the harsh use of vehicles by consumers.
In May 2011, at the Third Academic Annual Meeting of the Oil Products and Clean Fuels Branch of the Chinese Society for Internal Combustion Engines, the State Key Laboratory of Automotive Safety and Energy of Tsinghua University published the paper "Experimental Study on the Effect of MMT-Containing Gasoline on the Aging Performance of Three-Way Catalysts". The research results showed that only when the catalyst inlet temperature is relatively high (820℃) and the engine maintains a long-term steady-state condition does the use of gasoline with added MMT (18 mg Mn/L) cause a significant increase in catalyst back pressure; under other continuous steady-state conditions, the effect of MMT-containing gasoline and MMT-free gasoline on catalyst back pressure is basically the same. Therefore, the use of MMT is safe for vehicles.
After losing ground technically in the debate over MMT, automakers shifted the focus of the debate to health. The U.S. Environmental Protection Agency has conducted very extensive research on the health effects of MMT, and information from all official agencies shows that there is currently no evidence that the use of MMT causes health effects. These reports can be read on the website of the Federal Docket Management System (FDMS), www.regulations.gov, under docket number EPA-HQ-OAR-2004-0074.
II. The debate over MMT will continue
1. Consumers/inflation: the high cost to consumers has always been one of the major concerns of China's automobile development, and MMT helps reduce the cost to consumers by substantially increasing the octane number and significantly improving fuel efficiency.
2. Carbon emissions: by improving combustion efficiency, MMT helps reduce greenhouse gas emissions. China is currently the world's largest emitter of carbon dioxide and plays a key role in the fight against global warming. Moreover, China has also set ambitious greenhouse gas emission reduction targets, aiming to reduce greenhouse gas emissions by 40-45% by 2020 compared with 2005.
3. Energy security: reducing the manganese addition by one milligram per liter of gasoline means that China must import 1 million more tons of petroleum. Crude oil prices are rising continuously and are highly sensitive to geopolitics, so this point has become even more important. In addition, compared with MTBE, MMT produced through synthesis is not directly linked in price to crude oil prices.
4. Economic cost: if, instead of using MMT, the octane number of oil products is increased by increasing the degree of refining, the operating cost of the refining units alone would be about 20 times the cost of using MMT (excluding the investment in upgrading refining facilities). These additional costs would ultimately be passed on to consumers. Therefore, MMT plays a dual role for producers and consumers in controlling inflation. This is especially important for China at present.
5. Another contribution of MMT is that it does not involve agricultural products. Ethanol is widely considered a more environmentally friendly biological substitute for MMT, and China mainly uses grain and wheat as raw materials for ethanol. However, due to the frequent occurrence of droughts and floods, and the continuous rise in international grain prices, and in consideration of the Chinese government's emphasis on food resources, the idea of replacing MMT with ethanol is increasingly being questioned. In particular, MMT can achieve the same effects as ethanol, reducing petroleum demand and greenhouse gas emissions, without relying on food resources or increasing costs to consumers.
III. Misconceptions about MMT
1. The less manganese in gasoline, the less pollution vehicle emissions cause to the city
The manganese limit (0.016 g/L) in National III standard fuel is already within a reasonable range. Extensive market research has shown that the content of aromatics and benzene in gasoline with MMT added can usually be reduced by 30%. By producing clean gasoline to reduce vehicle exhaust, the emission of smog precursors can be significantly reduced.
2. Using MMT will cause damage to vehicle engines and exhaust emission systems
The results of more than 20 years of tests and research by authoritative institutions in the United States, Canada and other countries have repeatedly proven that the use of MMT does not cause harmful effects on vehicles, and does not cause engine blockage, exhaust emission or other problems. In China, third-party institutions have conducted extensive field tests and application studies to ensure that gasoline containing MMT is fully compatible with advanced automotive technology and that vehicles can run at maximum efficiency. The Ministry of Environmental Protection conducted extensive road tests on vehicles with National III or higher technology that had traveled 80,000 km, and the results showed that vehicle emissions were fully compatible with gasoline containing 0.018 g of manganese per liter. In 2010, the China Automotive Technology and Research Center conducted extensive assessments of a large number of in-service vehicles using MMT, confirming that they meet emission standards at extremely high mileages.
3. Using MMT is harmful to human health
Manganese, as an element essential to life, exists in food, water, air and soil. The U.S. Clean Air Act Amendments authorized the EPA to conduct extensive health tests on the use of MMT in gasoline. For more than 10 years, tests by third-party institutions have confirmed that the use of MMT in gasoline does not pose a greater risk to any human health or the environment.
4. It has nothing to do with politics
The use of MMT was originally a purely technical issue, but it has now evolved into a political topic and become a dispute over interests among different industries. Today, China's economy is facing the development bottleneck of resource shortage and ecological degradation, and with the energy crisis becoming increasingly evident, China needs to transform its economic growth model and improve efficiency. Using MMT is one of the effective measures to comprehensively solve energy saving, environmental protection and economic benefits in the refining field.
Different government departments and industries should formulate their own technical standards and industry standards based on national interests and actual national conditions. Local standards can refer to international standards, but there is no need to copy them entirely; comparing with the standards of developed countries may not conform to China's actual situation. Moreover, many developed countries have not formulated strict standards restricting the use of MMT, so there is even less need for China, a developing country with unbalanced economic development, to do so.
Some foreign institutions and enterprises are trying every means to promote European and American technical and industry standards in China, and it cannot be ruled out that they are trying to use this to facilitate the smooth import of their products into China. China should take a long-term view and formulate a set of industry and technical standards that not only conform to international norms and China's national conditions, but also help to control the discourse power of its large domestic market.
IV. The use of MMT around the world
1. The industrial application of MMT in the world began in Canada in 1977, when the transition to lead-free gasoline was being explored. The lead-free gasoline process has nothing to do with any lead poisoning incident; it is because the installation of exhaust catalytic converters on vehicles requires the use of unleaded gasoline. The transition to lead-free gasoline in the United States took twenty years, and extensive tests of MMT were also conducted. The U.S. Environmental Protection Agency approved the use of MMT in unleaded gasoline in July 1995, and the approval document confirmed: "MMT... will not cause or contribute to the failure of any vehicle emission control device or system".
2. Since 1997, MMT has been introduced into China. Since then, more and more countries have used MMT, including Belgium, the former Eastern European countries, South Africa, Venezuela, Iraq and Iran, on a relatively large scale.
3. Since 1995, the U.S. gasoline standard has set the MMT use limit at 8.3 mg Mn/L; since 1992, the Canadian gasoline standard has set the MMT use limit at 18 mg Mn/L. The EU imposed no restrictions on the use of MMT during the implementation of the Euro IV emission standards from 2005 to 2009.
4. Chinese refining enterprises strive to use MMT, but German and Japanese refining enterprises have given up MMT. Why? There are two reasons: first, the crude oil refined by refineries in those countries is lighter, so there is no shortage of gasoline octane number; second, the automobile industry in those countries is developed, and automakers have greater political influence. Under the EU gasoline standards, MMT could be used in Germany, but German refining enterprises have never used MMT. The crude oil in the United States is lighter, so there is no shortage of gasoline octane number and the amount of MMT used is relatively small.
V. Why does the national gasoline standard limit the manganese content of MMT
1. MMT is an additive that improves gasoline performance. All additives in gasoline that are not petroleum refining components, as well as MTBE, are subject to limits in gasoline standards.
2. During the formulation of the national gasoline standard, the automobile industry and the refining industry have been in constant dispute over indicators such as sulfur content, manganese content, olefin and aromatic content, and vapor pressure.
3. The release history of the national motor vehicle gasoline standard is shown in the table below:
National gasoline standard | Corresponding emission stage | Release/ implementation date | Implementation basis | Source | Manganese content |
GB17930-1999 | Unleaded gasoline | 2000-1-1 | GB17930-1999 | | 0.018g/L |
National II stage | 2005-7-1 | GB17930-1999 Amendment No. 3 | GBBWGJ [2005] No. 69 | 0.018g/L |
GB17930-2006 | National II stage | 2006-12-6 | GB17930-2006 | Technical requirements specified in Table 1 | 0.018g/L |
National III stage | 2010-1-1 | GB17930-2006 | Transition period for technical requirements in Table 2 until 2009-12-31 | 0.016g/L |
GB17930-2011 | National III stage | 2011-5-12 | GB17930-2011 | Technical requirements specified in Table 1 | 0.016g/L |
National IV stage | 2014-5-12 | GB17930-200X | From the release date, the transition period for technical requirements in Table 2 is three years | 0.008g/L |
GB17930-201X | National V stage | Not yet submitted for approval | | Review will only be organized after the National IV stage begins | Not yet demonstrated |
4. For the national motor vehicle gasoline standard GB17930, the transition period of the National II stage is four and a half years, and that of the National III stage is also four and a half years. The sulfur content in gasoline at the National IV stage will drop substantially, and the transition period will be at least more than five years.
5. Will MMT be banned at the National V stage?
The demonstration time for the National V stage of the national gasoline standard is after the actual implementation date of the National IV stage, i.e., at least after 2014, plus a five-year transition period, so the actual implementation date of the National V stage of the national gasoline standard will be at least after 2019. Even if it is in line with international standards by then, the EU set the limit on the use of MMT at 6 mg Mn/L during the implementation of the Euro V emission standards.
As the challenges to energy and the environment grow, requirements for vehicle emissions and fuel consumption are becoming increasingly stringent. Global engine technology is developing toward smaller sizes, direct fuel injection and turbocharging. These engine technologies create demand for high-octane gasoline, and the global market share of high-octane gasoline has been rising year by year. In the EU, gasoline of No. 95 and above already accounted for more than 95% of the total gasoline market in 2009. Chinese refining enterprises will face great challenges in the future. While continuously increasing investment and constantly updating refining processes, they will also face increasingly stringent gasoline indicators. In terms of supplying gasoline that meets market demand in the future, MMT will remain one of the most economical and effective blending means for high-octane gasoline.
VI. The use of MMT in China
1. The basic situation of China's refining industry
The development of China's refineries is based on the characteristics of China's crude oil, which is heavier with a relatively low content of light fractions. Therefore, the configuration of secondary processing capacity in China's refineries is mainly based on catalytic cracking units (which refine heavy raw materials after primary processing into gasoline and diesel), while the configuration of catalytic reforming units (which refine light raw materials after primary processing into gasoline) is relatively low. In the composition of China's gasoline, catalytic cracking gasoline components account for more than 70%, catalytic reforming gasoline components account for less than 20%, and high-octane components are relatively scarce. In the past decade, China's imports of crude oil have increased year by year, and the imported crude oil is also heavier. China's refineries are adapted to process poorer-quality imported crude oil, while the composition of the gasoline produced remains basically unchanged.
2. The basic configuration of China's refineries determines the basic composition of gasoline components and the relative scarcity of high-octane components. To meet the ever-expanding gasoline market and the demand for high-grade gasoline, the use of MMT by refining enterprises truly achieves two goals at once: it helps raise the grade of gasoline, and helps refineries reduce or lessen the degree of refining of gasoline, thus benefiting the energy saving and emission reduction of enterprises.
3. In refineries, to increase the production of high-grade gasoline, in addition to working hard to raise the octane number of the base catalytic gasoline, it is necessary to produce more high-octane components such as MTBE and reformate. The production energy consumption of high-octane components is greater than that of catalytic gasoline production, so increasing the output of high-grade gasoline by blending in more high-octane components means increasing production energy consumption. The production volume of high-octane components is also limited by the scale of raw materials and units.
4. MMT has been used in China for fourteen years. Since 2005, the grade structure of China's gasoline has changed from No. 90 gasoline accounting for more than 50% to, by 2010, No. 90 gasoline accounting for less than 10%. With little change in the component structure of gasoline, the output of high-grade gasoline has greatly increased, which is mainly attributable to the use of MMT.
VII. The impact of the National IV stage of the national gasoline standard (GB17930-2011) on MMT
1. The basic configuration of China's refineries has not changed, the basic composition of gasoline components has not changed, and the trend of the gasoline market's increasing demand for high-grade gasoline has not changed. In other words, the overall octane number gap of China's gasoline always exists, and this is a hard fact for a long period.
2. How should China's refining enterprises respond to the manganese content limit of 8 mg Mn/L?
① At present, the method of using MMT in refineries is to first blend the various components of the oil product according to calculated estimated values before adding MMT. If the octane number meets the standard, the oil product is shipped out; if not, MMT is added to bring the octane number up to standard before shipping, with MMT as the final adjustable variable. This blending method makes full use of tank capacity, improves blending efficiency, and increases the flexibility of oil product blending. This blending method also results in some gasoline containing MMT and other gasoline not containing MMT; and among different batches of MMT-containing gasoline, the MMT content may differ.
② After the manganese content limit of 8 mg Mn/L at the National IV stage, the method of using MMT in refineries will change. A feasible approach is to first blend the various components of the oil product and MMT according to calculated estimated values. If the octane number meets the standard, the oil product is shipped out; if not, MTBE is added to bring the octane number up to standard before shipping, with MTBE as the final adjustable variable. The advantage of this blending method is that all gasoline has MMT added, saving the maximum amount of high-octane components and enabling more high-grade gasoline to be produced; the disadvantage is that MMT is no longer the final adjustable variable, reducing the flexibility of oil product blending and sacrificing some blending efficiency. The characteristic of this blending method is that all gasoline has a fixed amount of MMT added (for example, 7 mg Mn/L). If this blending method is fully adopted, the space for MMT addition can be expanded and more high-grade gasoline can be produced. In 2009, 86% of the gasoline produced by Sinopec contained MMT, with an average concentration of 7.65 mg Mn/L, which is basically in line with the National IV stage manganese content limit of 8 mg Mn/L.
③ These two blending methods can transition into each other or coexist. An addition amount of 4-8 mg Mn/L is the most economical addition amount for MMT. Refineries generally design their oil product blending methods according to their own conditions and production plans.
