Basic knowledge of blast inhibitors

Thread Content

Basic knowledge of anti-knock agents: Octane rating is the most important quality indicator for automotive gasoline; it reflects the level of the refining industry as well as the design standards of vehicles. The use of anti-knock agents is an effective way to increase the octane rating of automotive gasoline. Explosion inhibitors mainly include alkyl lead, methylcyclopentadienyltricarbonylmanganese (MMT), methyl tert-butyl ether (MTBE), methyl tert-amyl ether, tert-butanol, methanol, ethanol, etc. Pollution-free anti-explosion additives represent the direction for future development. Tetraethyl lead was discovered in 1921 and began to be used in automotive gasoline in 1923; it was the only octane booster in use until 1959. In 1960, tetramethyllead entered the antiknock agent market, and the development of catalytic reforming processes led to a rapid increase in its use. Currently, tetramethyllead, tetraethyllead, as well as their chemical and physical mixtures, are still widely used as important anti-knock agents in certain regions. Alkyl lead antiknock agents have the advantages of simple production processes, low costs, and excellent performance, which is why they have always been highly effective octane boosters. In terms of performance and cost-effectiveness, there is currently no antiknock agent that can compare to lead alkyls. It is foreseeable that once lead dust can be effectively controlled, alkyl lead antiknock agents will continue to serve humanity. Driven by the need to control vehicle exhaust emissions and protect the environment, international efforts have restricted the addition of alkyl lead to gasoline, and there has been a gradual shift toward lower-lead and lead-free gasoline. Countries such as the United States, Canada, and Australia have advanced rapidly in the phasing out of lead in gasoline, while Western Europe is moving towards lower lead content in gasoline. It is reported that in 1990, 55% of gasoline consumption in the West was unleaded gasoline. The restriction on the use of alkyl lead antiknock agents will promote research and development of non-lead antiknock agents as well as more advanced refining processes. Unremitting efforts have been made to explore lead-free anti-knock agents. Research on aromatic amines and other nitrogen-containing compounds has shown that, although they have a certain effect in improving octane rating, they have not yet been put into commercial use due to issues such as high addition amounts, toxicity, and emissions. In 1959, a company in the United States introduced methylcyclopentadienylmanganecarbonyl onto the market as an anti-knock additive that worked in combination with tetraethyllead, and it was later used as an anti-knock additive on its own. This agent effectively increases the octane rating of gasoline. However, some studies suggest that MMT forms porous deposits on the inner surfaces of engine combustion chambers, which shortens the lifespan of spark plugs and can lead to an increase in manganese levels in the environment; as a result, the United States banned the use of MMT in 1978. Despite its many drawbacks, MMT is after all a highly effective anti-knock agent developed following alkyl lead. In the 1970s, oxygen-containing compounds appeared abroad as new components for gasoline blending. Among these, methanol, ethanol, methyl tert-butyl ether, and tert-butanol were particularly important; they all possess relatively high lead-free octane numbers and blending octane numbers, which facilitated the search for new gasoline formulation strategies. However, each of them presents issues such as volatility, miscibility, corrosivity, toxicity, exhaust emissions, and cost. MTBE is widely used around the world as a gasoline additive. It not only effectively increases the octane rating of gasoline, but also improves vehicle performance, reduces the CO content in exhaust gases, and lowers the production costs of gasoline. Since its introduction, the demand and consumption of MTBE have remained on a high growth trajectory, and its production technology has also become increasingly mature. But recently, California in the United States has banned the use of MTBE on the grounds of water pollution, and the U.S. **Environmental Protection Agency has taken similar actions. This indicates that the United States has begun to restrict the production and use of MTBE. The United States is a major consumer of MTBE, and this development will pose a threat to the MTBE industry. Currently, the world’s annual production capacity of MTBE for use in gasoline exceeds 21 million tons, and its survival is facing severe challenges due to threats of prohibition. Some experts also believe that the panic regarding MTBE in the United States will not spread to Europe and Asia in the near future. To date, there is no intention in Europe and Asia to ban MTBE, and these regions will continue to use MTBE as the main component of clean gasoline for some time yet. In particular, demand for MTBE in Asia is increasing rapidly. The demand for MTBE in our country is also growing rapidly. In particular, our country has recently promoted the use of high-octane lead-free gasoline, and new standards for clean urban vehicle fuel have been implemented first in Beijing, Shanghai, and Guangzhou, with MTBE being the main octane booster used. Therefore, the demand for MTBE in our country will continue to increase. With the commissioning of MTBE production units at enterprises such as Jihua Jinjiang Oil Chemical Plant, Linyuan Refinery, and Qiange Refinery, the number of MTBE production units in China has increased to 27, with a total annual production capacity of 620,000 tons. At present, China’s annual demand for MTBE for gasoline is 800,000 tons, resulting in a significant shortage. American Standard Alcohols has developed a biodegradable, water-soluble cleaning fuel additive, which is a mixture of straight-chain C1–C8 fuel-grade alcohols with an octane rating of 128. It can be used as a substitute for MTBE in gasoline additives, as well as as a replacement for tetraethyl lead in diesel blends. If this product is used as a substitute for MTBE, then the excess production capacity of methanol plants resulting from the ban on MTBE can be reconfigured to produce this product. A research institute in the United States is currently conducting separate tests on this product, with completion of these tests expected by the end of the year. Experts point out that methanol plants can produce this product by undergoing modifications and using patented catalysts to appropriately adjust certain reaction conditions. Alcohols are ineffective as gasoline additives due to their hydroxyl groups, but low-carbon alcohols such as methanol, ethanol, propanol, and tert-butanol, or their mixtures, have been used as gasoline additives. Its mixture, when used as a gasoline additive, has functions similar to those of MTBE and also offers cost advantages; it holds great market potential when used as a gasoline blending component. At present, China is focusing on promoting ethanol-blended gasoline for use in vehicles, which will help to advance the use of such gasoline in a proactive and cautious manner, ensure proper mixing of products, and provide guarantees. Ethanol gasoline technology is already highly mature abroad. Currently, the countries that use ethanol-blended gasoline in vehicles are **mainly the United States and Brazil**, with the **European Union** also using it.