Method one AlCl3 method, AlCl3 method adopts the typical Friedel-C rafts process, using AlCl3 complex as catalyst. The by-products of the reaction are mainly diethylbenzene and polyethylbenzene, and there are traditional AlCl3 method and improved AlCl3 method. In the traditional AlCl3 method, the reactants and the catalyst in the reactor form a three-phase, liquid aromatics, gaseous ethylene and liquid catalyst complexes. The catalyst complex is red and immiscible with liquid aromatics. During the reaction, ethylene is bubbled into a reactor containing two liquid phases to disperse and mix them. The molar ratio of ethylene and benzene is 0.3 to 0.35, and the reaction is carried out below 130°C and normal pressure. The conversion of ethylene is close to 100%, the yield of ethylbenzene is higher, and the amount of recycled benzene and ethylbenzene is small; the alkylation of benzene with ethylene and the transalkylation of polyethylbenzene can be carried out in the same reactor Finish. The disadvantage is that the reaction medium is highly corrosive, the equipment cost and maintenance cost are high, and the organic phase of the reaction product is washed with water and alkali to produce a large amount of waste water containing aluminum hydroxide slurry, and the waste catalyst has caused serious environmental pollution. The improved AlCl3 method, because the traditional AlCl3 method has problems such as serious pollution and corrosion and two liquid phases in the reactor, in 1974, Monsanto/Lummus company proposed the improved AlCl3 method, which makes the amount of AlCl3 catalyst larger. Reduced (only 1/3 of the traditional method), thus reducing the amount of waste catalyst treatment, and the feed ethylene concentration can range from 15% to 100%. By controlling the feeding of ethylene, the amount of AlCl3 catalyst is reduced to within the solubility range, so that the reaction can be carried out in a homogeneous liquid phase, and the yield of ethylbenzene is improved. 8。 The reaction temperature is 160 ~ 180 ° C, the pressure is 0. 6 ~ 0. 8MPa, and the molar ratio of ethylene to benzene is 0.8. When using dilute ethylene as the raw material, the H2S, O2, CO2 and H2O in the raw gas need to be purified to a mass fraction of about 5×10-6. Due to the obvious effect of this method in reducing costs, many traditional AlCl3 method devices have been transformed and expanded by the method of Mon san to/Lummus. However, this method only alleviates the problems of equipment corrosion and environmental pollution, and has not fundamentally solved it. The modified AlCl3 process is similar to the traditional AlCl3 process, the difference is that the alkylation and transalkylation reactions are carried out in two reactors. In the modified AlCl3 process, only dry benzene (instead of benzene and recycled polyethylbenzene) is continuously fed with ethylene and catalyst to the alkylation reaction, while the products of the alkylation reaction are recycled from the rectification column After the polyethylbenzene is mixed, the transalkylation reaction is carried out in another reactor. Method 2 Alkar method, Alkar method was developed by UOP in 1958 and industrialized in 1960, using BF3 supported on Al2O3 as a catalyst. The alkylation reaction can be carried out with ethylene with a concentration as low as 8% to 10% (mass fraction), so the treated FCC dry gas or coke oven tail gas can be used as the raw material. The reaction was carried out at 100-150°C and 2.5-3.5MPa, and the molar ratio of ethylene and benzene was controlled between 0.15-0.2. The transalkylation reaction was carried out in a separate reactor at a temperature of 180-230°C. The materials from the two reactors are combined into the purification system. The ethylbenzene purity of the finished product can reach 99.9%. The main advantages of this method are high catalyst activity, long life, good ethylbenzene selectivity, no corrosion and no pollution, short process, low energy consumption, and can be used for comprehensive utilization of low-concentration ethylene. The disadvantage is that the catalyst preparation conditions are harsh, the cost is more expensive, and it is easy to be poisoned and deactivated. The raw materials must be purified before the reaction, and the content of impurities such as H2S, CO2 and H2O is required to be less than 1×10-6. Method 3 Mobil-Badger gas-phase method, in 1976, Mobil and Badger jointly developed a gas-phase method for producing ethylbenzene with high-silicon ZSM-5 zeolite as a catalyst, the alkylation of benzene and ethylene, and diethylbenzene and All benzene transalkylation reactions have strong activity and good selectivity. The alkylation reaction is carried out under the gas phase conditions of high temperature and medium pressure, the reaction temperature is 370～430℃, the reaction pressure is 1.42～2.84 MPa, and the mass space velocity of ethylene is 3～5/h. The process can use concentrated ethylene as the raw material (in 1980, it was industrialized in the United States, with an annual output of 473,000 tons of ethylbenzene, the process flow is shown in Figure 2, and the mixed gas of dilute ethylene can also be used as the raw material, but in the treatment of FCC dry gas or When coke oven exhaust is used as a raw material, the content of impurities such as propylene, H2S, O2 and H2O in the raw material gas is extremely strict, and the mass fractions are all 10-6 (wherein sulfide≯10×10-6, H2O≯10 ×10-6), the raw material needs to be strictly refined, which can prolong the single-pass life of the catalyst, but the investment and energy consumption of the unit are relatively high (the unit consumption of benzene is 0.749t/tEB, and the unit consumption of ethylene is 0.168t/tEB). Completed in 19771 . 60,000 t/a ethylbenzene, the use of refinery gas as raw material to produce ethylbenzene industrial test equipment, and in 1991 in Stan low, England, built and put into operation the first large-scale industrial equipment of 160,000 t/a ethylbenzene. There is no environmental pollution and equipment corrosion problems in the production process. Although the catalyst is easy to coke and deactivate, it can be regenerated repeatedly and has a long service life. The thermal efficiency of the whole reaction is high, but the xylene content in the product is relatively high (~2000×10-6 ) [11, 12], affecting the quality of products. Method 4 U nocal/Lummus/UOP liquid-phase method, since the 1980s, U nocal/Lummus/UOP company of the United States has jointly developed a new technology for the liquid-phase production of ethylbenzene from benzene and ethylene on a solid acid catalyst. USY zeolite is the catalyst and Al2O3 is the binder. The reaction is carried out at 232～316°C and 2.79～6.99M Pa, the mass space velocity of benzene is 2～10/h, and the benzene/ethylene molar ratio is 4～10. The method does not produce wastes that pollute the environment, the reaction temperature is low (generally not more than 300 ℃), and the xylene impurity content in ethylbenzene is only 20-40×10-6, which is far less than the gas phase method. The operating cycle of the catalyst can be as long as one year, and the requirement for the purity of the raw material is not high. The used catalyst can be regenerated outside the vessel, the regeneration conditions are moderate, and the service life can be up to 3 years. In 1990, the first set of industrial equipment was put into operation in Oita, Japan, with an annual output of 212,000 tons of ethylbenzene. The process flow is shown in Figure 3. There are more than 20 sets of devices officially put into production and under construction in the world. However, this method can only be used for the alkylation of concentrated ethylene, and is not suitable for FCC dry gas or coke oven off-gas feedstock.
