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Clean gasoline production technology – China’s new gasoline standards require an olefin content of no more than 35% and a sulfur content of no more than 0.08% (800 μg/g), which still represents a significant gap compared to international standards. The new standard was implemented in the three cities of Beijing, Shanghai, and Guangzhou starting from July 1, 2000, and was rolled out nationwide from 2003. Sinopec Corporation will begin producing gasoline with an olefin content of less than 30% and a sulfur content of less than 200 μg/g starting in 2003. In 2005, it was required that gasoline contain less than 30 μg/g of sulfur. FCC gasoline in China accounts for over 80% of the total composition of refined gasoline. The focus of technological development is to reduce the sulfur and olefin content in FCC gasoline. 1 FCC gasoline desulfurization technology aims to minimize sulfur content while reducing octane loss as much as possible. The main measures are hydrogenation of the FCC feedstock, or selective or non-selective hydrodesulfurization of FCC gasoline. FCC feed hydroprocessing: VGO containing 1.2%~2.8% sulfur and HCGO with high sulfur and high nitrogen content, which are used as FCC feeds, must undergo hydroprocessing. Relevant technologies have been developed both domestically and internationally. Changling Refinery uses CH-20 type Mo-Ni catalysts for the hydrogenation of HCGO (with 0.89% sulfur and 0.45% nitrogen). The reaction conditions are: 5~8 MPa, 340°C. After hydrogenation, it contains 0.04% sulfur and 0.18% nitrogen. The Fushun Petrochemical Research Institute used an FDS-4 Mo-Ni catalyst to treat Middle Eastern VGO (with 2.28% sulfur content); after hydrogenation, the sulfur content was reduced to 0.18%. Empirical data shows that the sulfur content in FCC gasoline is 6% to 8% of the sulfur content in the feedstock. The sulfur content in the FCC gasoline produced from hydrogenated FCC feed can meet the Class 2 standards of the World Fuel Specifications. Selective hydrodesulfurization: Sinopec’s Research Institute of Petrochemical Technology has developed the FCC gasoline selective hydrodesulfurization (RHDS) technology, which has passed pilot-scale testing and will now undergo industrial-scale trials. Based on the distribution characteristics of sulfur and olefins in FCC gasoline, the entire gasoline fraction is divided into light/mid/heavy naphtha fractions (LCN/ICN/HCN), followed by selective hydrodesulfurization, which yields better results than hydroprocessing of the entire fraction. LCN (C5–C6) is a low-sulfur, high-octane fraction; the sulfides exist in the form of thiolic sulfur and can be removed by alkaline extraction without causing saturation of the olefins or a loss of octane value. HCN is a high-sulfur, low-olefin fraction; since sulfur is concentrated in fractions above 177°C and olefins are concentrated in fractions below 149°C, hydrodesulfurization of heavy naphtha fractions has little effect on olefin saturation, resulting in minimal loss of octane number. By combining HCN hydrogenation with LCN thiol removal, the sulfur content in FCC naphtha can be reduced to less than 200 μg/g, meeting the Class 2 standards of global fuel specifications, with an octane number loss of 1.0–1.5 units. The ICN fraction at 132–182°C contains thiophene; if this ICN fraction is subjected to selective hydrogenation, FCC naphtha can meet the Class 3 standards of the World Fuel Specifications. 2 FCC gasoline olefin reduction technology: Optimizing operations for olefin reduction – Operating conditions have a significant impact on the olefin content in FCC naphtha. Experience shows that for every 5.6°C increase in the riser exit temperature, the olefin content increases by 1%. At a constant reaction temperature, increasing the equilibrium catalyst activity to boost conversion can reduce the olefin content. At a constant cracking depth, by controlling the LPG content in FCC gasoline, the olefin content also decreases. The catalyst activity of Unit 3’s FCC unit at Yanshan Petrochemical Company increased from 50 to 60.8, the conversion rate rose from 56.7% to 61.7%, and the olefin content in the FCC gasoline decreased from 67.5% to 55.3%. Raising the temperatures at the bottom and top of the gasoline stabilizer reduced the olefin content in FCC gasoline from 55.3% to 52.3%. Alkene reduction catalysts: Sinopec’s Research Institute of Petrochemical Technology has developed the GOR series of catalysts, which have been put into industrial use at Luoyang, Takahashi, and Yanshan Petrochemical Companies. This type of catalyst improves hydrogen transfer activity by increasing the content of rare earth elements. Increasing the content of shape-selective molecular modifiers can compensate for the loss in octane number. The RFCC unit at Luoyang Petrochemical Complex uses GOR-C catalysts, which reduce the olefin content by 10.6%. The RFCC unit at Takahashi Petrochemical Company uses GOR-Q catalysts, which reduce the olefin content by 8.7%. The RFCC unit at Yanshan Petrochemical Company used GOR-DQ catalysts, which reduced the olefin content by 11.9%. Improved second-generation GOR olefin-reduction catalysts containing bimetallic oxides are also under development. Olefin-reducing additives: The Refining Research Institute of Luoyang Petrochemical Engineering Company developed the LAP additive, which has been tested in medium-scale ROCC-Ⅴ type heavy oil FCC units. When this additive was added to the LRC-99 catalyst at concentrations of 2.6%, 5.3%, and 7.4% of the total catalyst content, the olefin content in the FCC gasoline was reduced by 6.3%, 10.4%, and 12.8%, respectively. During testing in the RFCC unit of Jilin Petrochemical Company, the additive accounted for 5% of the total catalyst content, and the olefin content in the FCC gasoline was reduced by 7.2%. During tests at Tianjin Petrochemical Company, adding 5% reduced the olefin content in FCC gasoline by 8.1%. Second-generation olefin-reducing additives have also been developed and tested industrially in Tianjin Petrochemical Company’s 1.3 million t/a FCC unit, resulting in a 10%~11% reduction in the olefin content of FCC gasoline and an increase in its octane number by 1~2 units. MGD process: The MGD process developed by Sinopec’s Research Institute of Petrochemical Technology can increase the LPG yield from FCC by 1.3%~5.0%, and the diesel yield by 3%~5%. It also reduces the olefin content in FCC gasoline by 9%~13%, while slightly increasing the octane rating of gasoline. Additionally, it allows for flexible adjustment of the diesel-to-gasoline ratio, thereby improving the quality of gasoline. Using the RGD-1 dedicated catalyst, the reduction of gasoline olefins is primarily based on the re-cracking of gasoline olefins. Clean diesel production technology – World Fuel Specification Class 2 diesel has a sulfur content of less than 0.03% (300 μg/g), a total aromatic hydrocarbon content of less than 25%, a content of bicyclic, tricyclic and polycyclic aromatic hydrocarbons of less than 5%, and a cetane number of greater than 53. Category 3 diesel has a sulfur content of less than 0.003% (30 μg/g), a total aromatic hydrocarbon content of less than 15%, and a polycyclic aromatic hydrocarbon content of less than 2%. Category 4 standards have a sulfur content of less than 5–10 μg/g. China’s new diesel standard specifies a sulfur content of less than 0.2%, and it came into effect in January 2002. Sinopec has required that, since 2003, the three major cities of Beijing, Shanghai, and Guangzhou meet the Class 2 standards of international fuel specifications. MCI technology: The MCI technology developed by the Fushun Petrochemical Research Institute of Sinopec is suitable for processing catalytic light cycle oil (LCO). During tests of the MCI catalyst in industrial plants, at a pressure of 6.5 MPa, a reaction temperature of 305°C, and a space velocity of 1.32 h-1, a nitrogen removal rate of 95.6%, a sulfur removal rate of 99.7%, and a diesel yield of 96.1% were achieved. The cetane number increased by 12.1 units, the paraffin content rose from 32.5% to 45.2%, the aromatic content decreased from 65.9% to 54.9%, and the sulfur content dropped from 1546 μg/g to 29 μg/g. The cetane number of the diesel increased from 26.9 to 39, demonstrating the significant effect of the hydrogenation treatment. This catalyst possesses strong desulfurization capabilities and the ability to open aromatic rings. A new generation of catalysts and processes will also be developed for deep desulfurization and dearomatization. The RICH process developed by Sinopec’s Petrochemical Research Institute can be used for the hydrogenation reforming of LCO at medium pressure, achieving a diesel yield of 95% and an increase in cetane number of 10 units. Hydrocracking technology – China’s total hydrocracking capacity has reached 15 million tons per year. The Fushun Petrochemical Research Institute of Sinopec has developed multiple series of single-stage hydrocracking catalysts. The ZHC-01 amorphous catalyst has been used in the SSOT unit of Qilu Petrochemical Company, while the ZHC-02 catalyst (also amorphous) is used in the single-stage hydrocracking unit of Daqing Petrochemical Company. A new generation of catalyst containing molecular sieves, ZHC-04, has also been developed. The selectivity of ZHC-04 for middle distillate oils is 80.7%, which is 7.2% higher than 73.5% for ZHC-01. The advantages of this catalyst include a low aromatic content and high smoke point in jet fuel, a high cetane number in diesel, and a low BMCI value for the tail oil; however, the reaction temperature is 10°C higher. Zhenhai Petrochemical Company will use the 3996/ZHC-04 catalyst to build a 1.5 million t/a single-stage hydrocracking unit for processing sulfur-containing VGO from the Middle East. The unit will operate according to the SSOT or SSREC scheme, producing diesel that meets the requirements of World Fuel Specification Classes 3 or 4. Residue hydroprocessing/Heavy oil catalytic cracking (RHT/RFCC) technology – As China processes more imported sulfur-containing crude oil, the treatment of sulfur-containing residues has become a major challenge in residue processing. Combining residue hydroprocessing with RFCC can maximize the yield of light products. This combined technology is characterized by its ability to demetallize, desulfurize, and denitrate residue oil, and is suitable for processing Middle Eastern residue oils with high levels of metals, sulfur, and carbon residue. Hydroprocessing of high-sulfur residue can produce hydrogenated AR, which can meet the requirements for FCC feedstock. Thereby maintaining the activity of the FCC equilibrium catalyst, reducing coke deposition, and lowering the coking load on the regenerator. The RHT/RFCC combined technology enables a total yield of 82.2% when light distillates are blended with LPG, which is 20% higher than the corresponding yield of 60.2% achieved by the delayed coking/FCC combined technology. This processing scheme enables the maximization of light distillates, making full use of crude oil resources. Hydroprocessed AR used as an FCC feed can reduce the sulfur and olefin content in FCC gasoline and increase its octane rating. Due to its low impurity level, hydroprocessed AR helps to reduce SOX and NOX emissions in FCC flue gases. The two series of hydroprocessing catalysts for vacuum residue (VR) and atmospheric residue (AR), developed by the Fushun Petrochemical Research Institute of Sinopec, have been successfully applied in the 800,000 t/a VRDS unit of Qilu Petrochemical Company, the 2 million t/a S-RHT unit of Maoming Petrochemical Company, and the 2 million t/a ARDS unit of Dalian West Pacific Petrochemical Company. The industrially-scale residue hydrogenation unit with a capacity of 2 million tons per year, developed independently in our country, was put into operation at Maoming Petrochemical Company in 1999. The hydrogenated VR is entirely used as RFCC feed. The feedstock entering RHT consists of 71.5% VR of Iranian and Arab light crude oils and 28.5% Iranian VGO; its properties are as follows: sulfur content of 3.0%~3.8%, nitrogen content of 0.26%~0.34%, residue content of 12.6%~13.4%, and heavy metals (Ni+V) content of 107.4 μg/g. A fixed-bed reactor is used. The active ratio of the matching catalysts is HDM∶HDS∶HDN=45∶20∶35. The reaction conditions were: 365–385°C, space velocity of 0.2 h-1, and hydrogen/oil ratio of 650. Desulfurization rate: 92.4%, denitrification rate: 67.5%, demetallization rate: 85.5%, residual carbon removal rate: 69.9%. The total hydrogen consumption was 1.44%–1.62%. The quality of the hydrogenated VR is as follows: 0.4%~0.5% sulfur, 0.10%~0.12% nitrogen, 5% residue carbon, Ni+V at 17 PPm, and saturated hydrocarbons exceeding 50%. When hydrogenated VR is used as an RFCC feed (with LV-23 catalyst), the yields are 69%–70% for FCC light distillate oil, 78%–80% for light distillate oil plus LPG. The sulfur content in FCC gasoline is less than 200 μg/g; the octane number increases slightly, while the olefin content decreases. Combined technology of delayed coking/circulating fluidized bed (CFB) boilers – China’s delayed coking capacity has exceeded 21 million tons per year, yet the average energy consumption remains high at 1262 MJ/ton. The advanced delayed coking unit with a capacity of 1 million tons per year, developed in China, has been put into use at Shanghai Petrochemical Company. The efficiency of the heating furnace reaches 91%; steam is injected at multiple points, and online coke cleaning technology is employed. The unit features one heating furnace and two coke towers (with a diameter of 8.4 meters and a height of 21 meters). Optimized heat exchange processes have enabled the total energy consumption of this coking unit to be reduced to 808.05 MJ per ton, making it the coking unit with the lowest energy consumption in China. To address the difficulties in utilizing high-sulfur coke, China has developed a technology for burning high-sulfur coke in circulating fluidized bed (CFB) boilers. To address the issue of handling sulfur-containing coke when processing sulfur-rich residue oil in its coking unit, Zhenhai Petrochemical Company adopted a combination of delayed coking and circulating fluidized bed (CFB) boilers. The company uses two 220t/h CFB boilers, equipped with two 25MW generator sets. Sulfur-containing petroleum coke and limestone are continuously fed into the combustion chamber; the amount of limestone used is determined based on the sulfur content of the coke, in order to control SO2 emissions. Generally, the calcium/sulfur molar ratio is 2.0~2.5. Sulfur-containing coke is crushed to a diameter of ~17 mm, while limestone and dolomite are in the range of 0.45~0.90 mm. A calcium/sulfur molar ratio of 1.98 was used. The desulfurization rate is 90%.