According to the recent evaluation of Oil and Gas magazine and the investigation of various departments and oil companies, the world's remaining proven natural gas reserves are more than10.7 trillion cubic meters, but most of them have been shelved due to reasons such as being far away from consumers and transportation difficulties. GTL technology can provide consumers with substitutes for petroleum products, bring economic benefits to countries and regions with natural gas reserves, and at the same time avoid the combustion of natural gas resources associated with oil exploitation in the air. Not only makes full use of natural gas resources, but also protects the environment. The synthetic hydrocarbon prepared by GTL technology has excellent performance, and can be used directly or mixed with the fuel produced by low-quality crude oil to meet the increasingly demanding requirements of environmental protection and oil performance indicators. 2. Development of Fischer-Tropsch Synthesis The method of converting synthesis gas into liquid hydrocarbon under the action of catalyst was invented by German scientists Frans Fischer and Hans Tropsch in 1923, which is called Fischer-Tropsch for short. Fischer-Tropsch synthesis technology was first industrialized in Germany on 1932. Up to 1939, 9 sets of FT units in Germany produce 12000 barrels of products every day. After decades of ups and downs, the industrialized production of Fischer-Tropsch synthesis technology began to enter a new development track in the 1990s. With the decreasing and inferior oil resources and the increasing proven recoverable reserves of natural gas, GTL has once again become the focus of major oil companies. From 65438 to 0993, Shell put into production in GTL factory in Bintulu, Malaysia. In 2002, BP's experimental device in Nikisky, Alaska, USA was put into operation. In 2003, ConocoPhillips started this experimental device in Punka, Oklahoma, USA. In June 5438+ 10 of the same year, Shell signed the second GTL project in Qatar. In July, 2004, ExxonMobil signed a contract with Qatar * * Company to invest 7 billion dollars to build the world's largest GTL project in Las Lavan, northern Qatar, and it is planned to start operation on 20 1 1. Second, the technical transformation of base oil processing 1. Development of base oil preparation by crude oil processing technology The quality of lube base oil produced by petroleum refining technology mainly depends on the quality of crude oil and the technology adopted. Traditional production processes for processing lube base oil below API I include solvent refining, solvent dewaxing and clay supplementary refining, among which solvent dewaxing is the main production process in lube base oil processing. In this method, methyl ethyl ketone/toluene and methyl ethyl ketone/methyl isobutyl ketone are usually used as solvents. When the wax-containing base oil diluted and dissolved with solvent is cooled to-10 ~-20℃, the wax in the solution will crystallize out, and then the paraffin in the base oil will be removed by evaporation, stripping and filtration, thus reducing the pour point of lubricating base oil and obtaining the by-product industrial paraffin raw material. This production process is mainly physical, and the hydrocarbon structure has not changed. The quality of base oil produced depends on the content and properties of ideal components in raw materials. Because the impurities contained in this refining process can not be completely removed, the produced base oil has a high pour point and is not suitable for working in cold conditions. At the same time, due to the high content of non-ideal components such as aromatic hydrocarbons and poor oxidation resistance, it is easy to be excluded from the blending choice of high-grade lubricating oil. In order to meet the higher requirements of a new generation of automobile engines and high-performance equipment for lubricating oil, API II/III base oil prepared by hydrogenation process appeared in recent twenty or thirty years, which greatly improved the service performance of lubricating oil products and expanded the application scope of petroleum refining base oil, among which catalytic dewaxing (CDW) technology and isomerization dewaxing (IDW) technology were the representatives. Take Chevron as an example, its isomerization dewaxing technology generally includes three-stage total hydrogenation process: hydrotreating, isomerization dewaxing and post-hydrogenation refining. Impurities such as sulfur, nitrogen and metal in raw materials are removed by hydrogenation, and then the components with low viscosity index are converted into base oil with high viscosity index and low pour point through the conversion process of hydroisomerization dewaxing. After hydrotreating and isodewaxing, the stability of dewaxed oil is often not ideal because it contains a small amount of residual polycyclic aromatic hydrocarbons, and it is easy to change color and precipitate when it comes into contact with air under light, so it needs to be further hydrogenated and removed by atmospheric distillation and vacuum distillation. Therefore, the distillate of isomerization dewaxing reactor needs to enter the post-refining reactor for hydrogenation saturation after heat exchange to improve the color and oxidation stability of the product. Compared with Class I, API, Class III and Class IV base oils have lower contents of volatile substances, sulfur and aromatic hydrocarbons, higher viscosity-temperature coefficient and lower viscosity. Their gradually upgraded performance is being sought after by the market. Classification index of lube base oil is shown in table 1. In the American and European markets, due to the influence of automobile manufacturers and the Ministry of Environmental Protection, the consumption of API II and II II base oils is increasing at an annual rate of 8%. In 2004, the total market consumption of high-end base oils such as API, Ⅲ and Ⅳ in the North American market exceeded the total consumption of Class I base oils. During this period, Motiva and other base oil processing enterprises increased the production and processing capacity of API II and II II base oils, while Shell and other companies closed the API I base oil manufacturing plant.
2. The first generation GTL base oil GTL plant can produce clean synthetic alkyl paraffins, and at the same time prepare ultra-clean fuel through Fischer-Tropsch synthesis. Paraffin wax can be further converted into lube base oil without sulfur, nitrogen, aromatics and metal impurities, which is completely different from the base oil prepared by solvent refining or hydrofining in petroleum refining. Because the molecular structure of GTL base oil is basically isoparaffin, GTL base oil has the characteristics of low viscosity, cleanliness and long life, which provides a new choice for market demand. Two first-generation GTL base oil plants have been put into operation or small-scale trial operation in the world. The Fischer-Tropsch synthesis part of these two GTL units adopts fixed bed process. Shell's GTL plant in Bintulu, Malaysia started construction in 1993, with a daily output of 12500 barrels. The process adopted is the SMDS (Shell Intermediate Unique Synthesis) process of Shell. The produced paraffin products are transported to two base oil processing plants located in Yokkaichi, Japan and Petit-Couronne, France, where appropriate base oil components containing wax oil are prepared by hydrocracking and hydroisomerization, and then Shell XHVI base oil products are prepared by simple solvent dewaxing process. Syntroleum's experimental device in Tulsa, Western Australia was put into operation in June 5438+February 2000, and the project was forced to terminate due to the bankruptcy of its partner Enron. 3. The second generation GTL base oil processing technology Based on the market demand of ultra-clean diesel, many famous petroleum and petrochemical companies in the world have increased their investment in GTL technology, and the planned GTL base oil large-scale production facility is located in the north of qatar peninsula. ExxonMobil's investment in the GTL plant in Qatar is close to $7 billion, and the plant after commissioning will be the largest GTL plant in the world. The plant will adopt ExxonMobil's patented AGC-2 1 technology, and 20% of the total production capacity will be used to produce high-performance base oil. In addition, the MWI (paraffin isomerization process) which is proprietary to our company will be used to feed high wax content raw materials such as wax oil and soft wax into a fixed bed reactor equipped with selective molecular sieves and convert them into high viscosity index base oil (see Figure 2). The plant is expected to produce 6,543.8+500,000 tons of base oil annually, which is about 654.38+07% of ExxonMobil's existing global base oil production. The refinery of Antelope GTL base built in Qatar by Chevron and Sasol of South Africa will be put into operation in the first half of 2008. Shell's GTL plant in Qatar is called Pearl GTL Project, which will rely on the SMDS process of Shell's GTL plant in Malaysia. The first phase project is expected to be put into production in 2009, with an annual output of 500,000 tons of GTL base oil. After the second phase of the project is completed, the production capacity will reach 6.5438+0 million tons/year, accounting for about 25% of Shell's global base oil production capacity. It is predicted that the potential daily output of GTL base oil will reach 30,000 ~ 50,000 barrels by 20 10 ~ 20 12. By then, it will have a certain impact on the high-grade base oil market. The production plans and production dates of the three major GTL base oil producers are shown in Table 2.
Third, the performance of GTL base oil The internal combustion engine oil specifications being formulated or implemented, such as API SL/SM and ILSAC GF-4, need lower viscosity to meet the fuel economy standards. At the same time, environmental regulations require reducing the emission of particulate pollutants (PM) and nitrogen oxides (NOX) from heavy-duty diesel engines, as well as the extra smoke generated by the design of low NOX internal combustion engines. In order to improve the performance of heavy-duty diesel engine oil, it is necessary to improve the performance of the base oil used to avoid premature engine wear. Automobile manufacturers are filling their passenger cars and trucks with long-life automatic transmission fluid or hydraulic transmission fluid to reduce the cost of warranty maintenance. GTL base oil shows excellent oxidation stability, low temperature performance, low NOACK evaporation loss and high viscosity index because of its almost zero sulfur, nitrogen and aromatic hydrocarbon content and almost completely isomeric alkane structural characteristics, which can meet the market demand for higher performance base oil. At present, the production technology of GTL base oil has developed to the point where the viscosity grade (100℃) can be prepared, ranging from 2 centistoke to more than 9 centistoke, and even the bright oil with high viscosity grade can be produced. It breaks through the narrow limit that hydrogenation process can only produce API II/III base oil with grades below 9cSt, and also expands the demand for high viscosity and high performance base oil in the industry. The performance comparison of different grades of base oils classified by API is shown in Table 3. The test data of the first generation GTL base oil products are the basis for people to evaluate the new generation base oil products. At present, the daily output of Shell's GTL base oil factory XHVI(r) in Japan is about 65,438+000 barrels, which has been used for blending passenger car engine oil (PCMO) and automatic transmission fluid (ATF). Syntroleum Company conducted engine bench test on GTL base oil products produced by its test device. The results show that the performance of the product can not only meet the current specification requirements of ILSAC GF-4, but also show the competitiveness of the product in terms of performance in the program Ⅲ F test to investigate engine fuel consumption and wear and the ⅵ B test to investigate fuel economy (see Table 4).
The work of the second generation GTL base oil production process test device also shows that the product contains a small amount of monocyclic hydrocarbon molecules, and the device can produce GTL bright oil. Some GTL base oil manufacturers have begun to provide their test products to additive companies and independent lubricating oil blending plants, such as Fuchs and Castrol. Four. Market prospect analysis of GTL base oil In order to reduce exhaust emissions and improve the energy efficiency of internal combustion engines, automobile manufacturers need high-performance base oils, such as API ⅲ and API ⅳ base oils. Lubricating base oil prepared by GTL technology is an important substitute for API Ⅲ/Ⅳ base oil, which has good viscosity-temperature performance, oxidation resistance and cold start performance at low temperature. The lubricating oil blended with this base oil can meet the operation needs of modern internal combustion engines. GTL plant is mainly used to produce high clean fuel, naphtha and special chemical products. Only a few companies prepare part of base oil in order to maximize the composition value of processed products, and its share is generally 10% ~ 20%. Although the market size of lubricating oil and paraffin accounts for only 5% of the fuel market, experts predict that the high-purity base oil prepared by GTL method will have an important impact on the market. Kline's analysis shows that the price of synthetic polyalphaolefin is generally 4.5 ~ 8 USD/gallon, and the price of API base oil is 1.6 ~ 2.5 USD/gallon. The price of GTL base oil is better than the above two prices. It will not only have an impact on the current API II base oil market, but also become a direct competitor of polyalphaolefins in terms of low viscosity and fuel economy (especially SAE 0W) due to its excellent low temperature performance and oxidation resistance. GTL base oil will also compete with API Ⅲ/Ⅳ base oil because of its small evaporation loss. If the large-scale GTL base oil plant described in this paper can produce normally, the output of GTL base oil will increase greatly, so it is not far away for GTL base oil to compete with APIⅲ/ⅳ base oil or even ⅱ base oil for the market. It can be predicted that GTL base oil will be first applied to high-grade internal combustion engine oil, automatic transmission fluid and other formulations, and will be extended to Japan from Europe and North America, and finally applied to the Asia-Pacific region. With the commissioning of large GTL units of Shell, ExxonMobil and Chevron Sasso, GTL base oil will replace traditional base oil and be widely used in hydraulic oil, railway internal combustion engine oil, industrial gear oil and other fields. Class I base oil manufacturers will face greater pressure on the supply of new base oil. However, the market preference for API Ⅲ and API Ⅳ base oils and the huge profit margin of API Ⅱ base oil production will force GTL manufacturers to consider whether their products can compete with API Ⅱ base oils by lowering prices or sacrificing production, so as to maintain the price advantage of API Ⅲ/Ⅳ. Considering the above economic factors, the production of GTL base oil will be carried out in a small experimental device. At present, the products of the above-mentioned major companies' own lubricating oil brands are still using GTL base oil, and the prospect of large-scale GTL base oil devices is still difficult to decide for the time being. V. Summary and Thinking In order to improve fuel economy, more low-viscosity lubricants are needed. For example, SAE 0W/20 engine oil limits the high and low temperature viscosity of the engine. At present, this kind of oil can only be blended with the mixture of polyalphaolefin and ester oil, but it is difficult to meet the requirements of low viscosity and low volatility with API ⅲ base oil. GTL base oil can meet the requirements of this new specification. As an important raw material for producing lubricating oil, whether GTL base oil can be successful in the market depends on many other factors. If manufacturing enterprises want to achieve market success in addition to meeting their own needs, they must make GTL's factory process and quality control continuously meet the demand of producing high-quality GTL base oil. Because the proposed GTL base oil large-scale factory is located in a remote area, that is, far away from the end consumer market, the reliability of its logistics supply link is very important. In addition, lubricating oil blending plants and distributors should also consider how to improve the price competitiveness of GTL base oil in order to open up a larger market. GTL base oil, as a new generation base oil, needs a lot of necessary tests to enter the market instead of other products, including engine bench test, additive compatibility, product compatibility, OEM certification, etc., and needs a lot of funds for related research and supporting services.
GTL means Louis Koo.