Looking for information on the process of isomerizing butylene skeletons into isobutylene, along with technical FAQs to learn from*

I searched for you for ages. Can’t find it. I searched for some information; I hope it will be helpful to you. I can be contacted by fellow netizens who have related questions: @zhangqi1234, @zhjy200311, @wsh7014, @河边水草, @那疼、绕心弦, @紫藤, @liu421454805, @hu792016761. I myself am the operator of this equipment. Please provide detailed solutions to the following issues: 1. Problems related to n-butene isomerization: http://bbs.hcbbs.com/thread-1235316-1-1.html (Source: Haichuan Chemical Engineering Forum). 2. I would like to ask about the process for producing isobutylene through the isomerization of 1-butene and 2-butene: http://bbs.hcbbs.com/thread-424427-1-1.html (Source: Haichuan Chemical Engineering Forum). 3. Skeletal isomerization of n-butene: http://bbs.hcbbs.com/thread-896890-1-1.html (Source: Haichuan Chemical Engineering Forum). The isobutane dehydrogenation method is a highly competitive production route for isobutylene. It makes use of the 20%-40% isobutane contained in oilfield gas; after separation in an isobutane removal tower, the isobutane coming out of the top of the tower is fed into a dehydrogenation unit where it is converted into the desired product, isobutylene. If it is solely for obtaining chemical raw materials, the resulting isobutylene can be used directly. To obtain a product of high purity, isobutylene can be fed into the MTBE synthesis unit, while butane flowing out from the bottom of the tower is sent to the isomerization unit. The products of isomerization are then returned to the deisobutanization tower and subsequently to the dehydrogenation unit to produce isobutylene. In this way, C4 hydrocarbon resources are made full use of, which is why this approach is favored by many producers. The key to the technology is having excellent catalysts. Isobutane dehydrogenation is a highly endothermic process governed by kinetics. High temperatures are beneficial for improving the yield; however, at high temperatures, the catalyst tends to deactivate ； A lower hydrogen pressure is favorable for dehydrogenation, but in practice, a hydrogen-rich environment is required to suppress coking and remove carbon deposits, which makes it somewhat difficult to carry out this process. The industrial technologies that have been developed abroad include UOP’s Oleflex process, Lummus’ Catofin process, Phillips’ STAR process, Snamprogetti’s FBD-4 process, and Linde’s Linde process. The company’s process for producing isobutylene via isobutane dehydrogenation consists of three stages: reaction, continuous catalyst regeneration, and product recovery. The catalyst used is a multimetallic compound based on platinum, supported on spherical alumina. This method achieves a total selectivity of 91%-93% (mol) for converting isobutane into isobutylene. In the former Soviet Union, a fluidized bed using an aluminum chromate catalyst was employed for the dehydrogenation of isobutane (as well as n-butane or a mixture of isobutane and n-butane). This method proved to be effective: the conversion rate of isobutane reached 50%–55%, while the selectivity for converting it into isobutylene was 82%–86%. There are many companies in the country that have ties to Russia; Panjin and Yun seem to be those that have reached a practical stage in this regard. Isobutane dehydration depends on how isobutylene is utilized thereafter – if it is further processed into polyisobutylene, butyl rubber, isoprene rubber, or MMA, the benefits will be significant. ! The specific consumption for isobutane dehydrogenation is 1.16 tons of isobutane per ton of isobutylene. China has already adopted the technology from the Russian YARSINTEZ Synthesis Institute to build industrial facilities for isobutane dehydrogenation, using a fluidized bed process with a conversion rate of over 50%. According to the contract terms, Russia shall not transfer this technology to either party within 4 years after the contract is signed. In China, companies such as Shandong Yuhuang are constructing industrial facilities of a scale of around 200,000 tons each. 8 C' Y( P1 F, N5 T( Z Due to the high investment costs, - m7 |5 G3 }5 unless isobutylene is processed further into products such as butyl rubber or isoprene, a production volume of 100,000 tons certainly cannot achieve economic viability. Our company is a private enterprise specialized in the advanced processing of C4 compounds. We currently produce MEBE, high-purity isobutylene, n-butylene isomerization products, and aromatized substances. The isobutane dehydration process you mentioned is also part of our company’s development plans. May I ask if this process has been put into industrial use yet, or is it still at the laboratory stage? What is the level of olefins in the exhaust gases resulting from the aromatization process? I think there are similarities between your dehydration catalysts and those used for isomerization. In China, technology from Russia’s YARSINTEZ Synthesis Research Institute has been introduced to build industrial facilities for isobutane dehydration, using a fluidized-bed process with a conversion rate of over 50%. According to the contract terms, Russia shall not transfer this technology to either party within 4 years after the contract is signed. Explanation of the comprehensive utilization methods for C4 compounds: Butane is most commonly used in the production of maleic anhydride and butadiene, and it is primarily utilized in the synthesis of various materials such as ABS, SBS, cis-butyl rubber, nitrile rubber, neoprene, and styrene-butadiene rubber. Butadiene-based adiponitrile represents BASF’s most advanced technology. C4 compounds can also be used as feedstock for ethylene cracking; isobutylene can be converted into MTBE and tert-butanol, from which high-purity isobutylene can be produced, which in turn can be used to manufacture methyl methacrylate, butyl rubber, polyisobutylene, and lubricant dispersants. Butene-1 and butene-2 can be used to produce methylethyl ketone, as well as butadiene through dehydration processes. Explanation 2: Isobutane is rarely used in the chemical industry due to its inert properties, which make it difficult to utilize in advanced processing; it is mainly used for direct alkylation to produce gasoline. Butane can be converted into maleic anhydride through oxidation. The most widespread use of isobutylene is in its reaction with methanol to produce MTBE; nowadays, it is also frequently used as a raw material for the production of methyl methacrylate (MMA). Butylene is mainly used for oxidative dehydrogenation to produce butadiene and maleic anhydride, as well as methyl ethyl ketone. Additionally, 1-butene can be used as a monomer for polyethylene, as a raw material for the production of sec-butanol and other products obtained through solution and gas-phase polymerization. The main uses of 2-butene are: (1) It is used in the production of alkylated gasoline via indirect alkylation technology; this constitutes the primary use of 2-butene, accounting for approximately 90% of its total consumption. (2) Production of propylene from 2-butene and ethylene. (3) 2-butene is hydrated to form sec-butanol, which is then dehydrogenated to produce methylethyl ketone. Starting from the early 1990s, when butadiene was used exclusively in the production of synthetic rubber, its applications have gradually expanded to include the production of synthetic resins, thermoplastic elastomers, styrene-butadiene latex, and other organic chemical products. In particular, there has been a significant increase in consumption of products such as acrylonitrile-butadiene-styrene (ABS) resin, styrene-butadiene block copolymers (SBS) thermoplastic elastomers, and styrene-butadiene latex. Furthermore, butadiene can also be directly used to synthesize various basic raw materials, such as butanediol, furan, styrene, adiponitrile, caprolactam, butyraldehyde/butanol, as well as 2-ethylethanol and 1-octene/1-octanol. It is explained that 53% triisobutylene (IB) and 47% ethanol (EtOH) can be used to synthesize ETBE (Ethyl Terbutyl Ether). ETBE is a high-performance component used in the formulation of high-octane gasoline. ETBE, along with ethanol and MTBE, are high-octane gasoline improvers, also known as “bio-gasoline additives”. , M8 o9 X$ @$ The maximum amount of ETBE that can be added to gasoline is 17Vol%. ETBE not only improves the octane rating of gasoline but can also be used as a co-solvent. ETBE has a high boiling point and does not form azeotropic compounds when mixed with hydrocarbons. This not only reduces air resistance inside the engine but also lowers evaporation losses. ETBE can also be broken down by aerobic microorganisms. Therefore, ETBE not only enables the octane rating of gasoline to be improved, but also enhances its economic efficiency and safety; thus, it is an excellent additive with great market potential. Background information 1. “High-octane gasoline” and its development trends. When gasoline burns in the cylinders of an automobile engine, insufficient oxygen within the cylinders leads to incomplete combustion. This results in intense vibrations of the engine, thereby reducing its output power and causing damage to its components. This is what is referred to as the anti-knock property of gasoline. The numerical indicator that reflects a gasoline’s resistance to detonation is called the octane rating, which is what people usually refer to as the grade of gasoline. For example, “90#” or “93#” gasoline indicates its resistance to detonation; the higher the number, the better the resistance to detonation. Using high-octane gasoline becomes an important means of protecting car engines and improving driving performance. A way to improve the anti-knock properties of gasoline is by adding other chemical substances to it. In the past, tetraethyl lead was commonly added, resulting in lead-containing gasoline. Due to the harmful effects of lead on human health, its use has been banned worldwide since 1997. Commonly used high-octane gasoline grades at present include lead-free gasoline with octane numbers of 92, 93, 95, 97, and 98. Ether compounds such as methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and methyl tert-amyl ether (TAME) are excellent blending components for producing lead-free, oxygenated, high-octane gasoline. A As times progress, environmental protection issues are receiving increasing attention from people. To reduce air pollution caused by vehicle exhaust, countries around the world are continuously establishing stricter gasoline standards. Over the past decade, methyl tert-butyl ether (MTBE) has served as a key additive in new formula gasoline (RFG) in the United States, as well as in gasoline in many countries and regions including Taiwan, used to increase gasoline octane rating and reduce vehicle emission pollutants. However, in recent years, oil tank leaks and MTBE contamination of groundwater have occurred in several states in the United States (especially California), sparking concern and panic among various parties. Recent scientific research has uncovered the disadvantages of MTBE: it is not easily decomposed and can cause pollution to groundwater ； It has a slight odor that makes drivers uncomfortable; it can cause reactions such as nausea, eye pain, and herpes outbreaks. The United States has recently passed a \"Clean Fuel Act\" that will ban MTBE over a period of 4 years starting in 2004. Once MTBE is banned, issues will arise regarding what compounds will replace octane numbers in gasoline, what will happen to the related production equipment, and what uses will befall the raw material, isobutylene. Among the existing alternatives to MTBE, ethanol is the most popular choice; however, in the United States it faces issues such as insufficient domestic supply and high prices. Although tax incentives are available, it remains uncertain whether these will persist. Moreover, ethanol has a relatively high vapor pressure (18 psia), which means that isooctene – a blending component with a low vapor pressure – is a more suitable option. Additionally, ethanol tends to absorb dust and water-soluble impurities, making it unsuitable for transportation via pipelines; thus, its blending is usually carried out at oil storage facilities. As for the utilization of isobutylene, efforts are currently underway in two main directions: one is to dimerize isobutylene into isooctene, which is then hydrogenated to produce isooctane—a high-octane gasoline blending component; the other is to react it with ethanol to synthesize ethyl tert-butyl ether (ETBE) ； Although ETBE belongs to the same category as MTBE, it has a higher octane rating (111), a lower Raoult vapor pressure (4 psia), and less water solubility than MTBE; therefore, it is more suitable than ethanol as an oxygenate additive for gasoline. Additionally, ETBE has a narrower distillation range compared to isooctane, which helps to improve the drivability index ； Regarding DI and the control of VOCs (volatile organic compounds) during blending, the U.S. Treasury Department has currently agreed to provide tax incentives for the ethanol component when ETBE is blended into gasoline. Europe is the second-largest market for MTBE, and the European Parliament has issued directives aiming for 5.75% of transportation fuel consumption (based on energy content) to come from biofuels by 2010. Biodiesel will become the primary biofuel. The majority of ethanol growth in Europe is expected to come in the form of ethyl tert-butyl ether (ETBE). Several MTBE plants have already been converted to produce ETBE, and the conversion of additional plants along with a few new ETBE plants is expected to be completed by 2010; consumption of ETBE is projected to rise to between 2.15 million and 2.57 million tons per year. Europe’s ethanol consumption (as a direct blending component or feedstock for ETBE) is expected to rise to 1.07–1.5 million tons per year. Looking ahead, global gasoline standards are becoming increasingly stringent. In addition to the requirements regarding oxygen and sulfur content, other specifications such as high octane rating, low RVP, low olefin content, and low aromatic hydrocarbon content will all increase the cost of gasoline. In the future, there might also be an additional requirement related to the \"drivability index\" (DI)

The skeletal isomerization of n-butene to isobutene can be classified into two types based on the catalyst composition: the alumina process and the molecular sieve process

The advantage of the alumina catalytic process is that the catalyst is inexpensive and readily available, but it has low activity and requires high reaction temperatures, which is thermodynamically unfavorable for the formation of isobutylene. The yield of this process is around 30%, and the alumina catalyst deactivates relatively quickly. The activity of molecular sieve catalysts is significantly higher than that of alumina catalysts; the reaction temperature can be reduced to 350–400°C, and the yield reaches around 40%

Please explain in detail the solution: The technological principle behind the isomerization of n-butylene to isobutylene involves the use of a highly selective molecular sieve catalyst to facilitate a skeletal isomerization reaction of n-butylene within the C4 feedstock, thereby producing isobutylene. The technological characteristics of the process for producing isobutylene through the isomerization of n-butylene are that no diluent gases such as nitrogen, hydrogen, or water vapor are required; the reaction pressure is low (approximately 0.02–0.07 MPa); the reaction temperature is moderate (300–420°C); and the reaction materials do not need to be highly purified. As a result, the process flow is simple, and the investment and operating costs are low. The reaction mechanism is as follows: It is generally believed that the isomerization of n-butylene follows a single-molecule reaction mechanism. First, n-butylene is activated at the acidic active site of the catalyst to form a primary carbocation intermediate; subsequently, this carbocation intermediate rearranges into a protonated cyclopropane intermediate. When the cyclopropane intermediate opens up, a primary butyl carbocation is formed, which is eventually converted into isobutylene. During this process, double-bond isomerization and cis-trans isomerization also occur. In addition to the main reaction of butene skeleton isomerization, side reactions such as olefin polymerization, cracking, aromatization, and carbon deposition also occur during the reaction process. Butene molecules can undergo dimerization or trimerization reactions at highly acidic active sites, and the resulting oligomers then undergo cracking reactions to produce smaller olefin molecules such as propylene and pentene ； These oligomers can further polymerize to form long-chain hydrocarbon molecules, or undergo aromatization to become aromatic hydrocarbon molecules ； This further leads to the deposition of coke on the catalyst surface, covering the acidic active sites or blocking the catalyst pores, thereby causing the catalyst to become inactive. The occurrence of these side reactions is related to the catalyst chosen; by properly optimizing the type and structure of the catalyst, the occurrence of side reactions can be minimized. Reaction temperature: The reactor inlet temperature is the main operational parameter for controlling the reaction. As the reaction proceeds, the catalyst activity gradually decreases, resulting in a lower isobutylene conversion rate. To ensure the isobutylene conversion rate, the reaction temperature must be increased gradually. From the reaction mechanism, it can be seen that the upgrading reactions include both exothermic and endothermic reactions, with an overall slight temperature rise. However, reactions such as naphthenes dehydrogenation and alkane cyclodehydrogenation are endothermic processes, and raising the temperature appropriately helps to increase the butene conversion rate ； From the perspective of chemical kinetics, increasing the reaction temperature can accelerate the rate of chemical reactions, which is more conducive to butene isomerization. However, excessively high reaction temperatures promote the intensification of side reactions such as thermal cracking, resulting in an increased coke yield. Meanwhile, the stability of the catalyst, including its thermal stability and carbon tolerance, is affected. During the reaction process, the catalyst’s activity decreases due to carbon deposition. To maintain an adequate reaction rate, the reaction temperature should be increased gradually as the catalyst activity decreases. Therefore, the reaction temperature is selected to be 370–430°C, at which point the properties of the product and its distribution are relatively favorable. Feed space velocity: Space velocity reflects the length of the reaction time. For a given reactor, the higher the space velocity, the greater the processing capacity. The maximum reaction space velocity that can be used mainly depends on the activity level of the catalyst. In non-hydrogenation reactions, the higher the space velocity, the shorter the residence time of the feedstock in the catalyst bed, the fewer side reactions occur, and the conversion rate of isobutylene is higher. However, if the air velocity is too high, the catalyst’s activity declines rapidly, the reaction temperature rises quickly, which results in a shorter reaction cycle for the catalyst and frequent coking in the reactor ； Conversely, if the feed space velocity is too low, although the reaction cycle is prolonged, there are more side reactions and the yield of the desired product decreases. By controlling the processing load at 60–120%, a good product distribution can be ensured, and the catalyst also enjoys a longer operational cycle. Reaction pressure: The currently used catalysts have a high carbon capacity and good stability, allowing for the use of lower reaction pressures. However, excessively low pressure is detrimental to the operation of air compressors. Therefore, it is reasonable to control the reaction pressure at 0.10 MPa(g).

I want to take on a task! But there aren’t enough Haichuan coins! We can communicate together and improve together!

Please provide a detailed explanation of the solution: UOP butamer process

This post was last edited by njdlmyl on 2016-6-23 at 14:11. There are nearly 20 sets of butylene isomerization facilities in China, all using highly mature technologies. The process is simple: it consists of a reaction system, a compression system, a distillation system, and a regeneration system. We’ve designed quite a few things.

Yes, I’ve been revising the operating procedures recently and looking for some materials for reference