Table of Content

12 December 2023, Volume 54 Issue 12

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SRJET TECHNOLOGY FOR HYDROGENATION OF WASTE OILS AND FATS TO PRODUCE BIO-JET FUEL AND ITS COMMERCIAL APPLICATION

2023, 54(12):  1-5. 

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In order to meet the demand for bio-jet fuel in China's aviation market, SINOPEC Zhenhai Refining & Chemical Company has built a 100 kt/a bio-jet fuel production plant using waste cooking oil as feed, adopting the SRJET technology developed by SINOPEC Research Institute of Petroleum Processing Co., Ltd.. The first operation of the device was successful, and the product met the requirements of No.3 jet fuel standard. The bio-jet fuel products successfully obtained the sustainable certification certificate issued by RSB and the bioaviation coal airworthiness certificate approved by the Civil Aviation Administration of China, and successfully realized commercial flight.

OPERATION ANALYSIS OF THE FIRST FIXED-BED HYDROTREATING UNIT FOR LOW SULFUR AND HIGH NITROGEN RESIDUE IN CHINA

2023, 54(12):  6-13. 

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Unit A was the first fixed bed residue hydrogenation unit for processing low sulfur and high nitrogen residue in China. Its mass fraction of sulfur(1.38%) was lower and mass fraction of nitrogen(0.68%) was higher. The feedstock properties of the fixed-bed hydrogenation unit for high sulfur residue were significantly different from those in the past. In order to analyze the hydrogenation reaction characteristics of low sulfur and high nitrogen residue, a comparative experiment was carried out in the laboratory with the hydrotreating of high sulfur residue, and the operating data of industrial units of processing low sulfur and high nitrogen residue and high sulfur residue were also be compared. In the pilot test, the same catalyst gradation was used under the conditions of reaction temperature 375.5 ℃, H2 partial pressure 15.0 MPa, liquid volumetric space velocity 0.23 h^-1, and volume ratio of H2/oil 700. The results showed that the reduction rate of carbon residue was 49.83% for low sulfur and high nitrogen residue, and 69.10% for high sulfur residue. In commercial application, the carbon residue reduction rate was 48.14% for low sulfur and high nitrogen residue with 11.32% of carbon residue in unit A, and 55.39% for high sulfur residue with 11.50% of carbon residue in unit B. The results of both laboratory and commercial application showed that it was difficult to hydrogenation the carbon residue precursors in low sulfur and high nitrogen residual oils. Unit A has completed 6 cycles of operation since it was built. The average sulfur content in the feedstock in each cycle was no more than 1.51%, and the average nitrogen content in the feedstock was no less than 0.62%. By analyzing the operation of Unit A, it was found that the scaling of the high-pressure heat exchanger made it difficult to increase the reaction temperature in the middle and end of run. The proportion of vacuum residue in the feedstock had a significant impact on the length of the operating cycle. The operating cycle was short when the proportion of vacuum residue was high, and vice versa. The measure to eliminate the operation bottleneck of the unit is to retrofit the high-pressure heat exchanger and reactor system.

DEVELOPMENT AND COMMERCIAL APPLICATION OF LARGE-SCALE COUNTERCURRENT CONTINUOUS CATALYTIC REFORMING PROCESS

Wang Ting

2023, 54(12):  14-19. 

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Taking the design of a 2.6 Mt/a SINOPEC Countercurrent Continous Catalytic Reforming (SCCCR) unit as an example, through the upgrading of the regeneration process, the conditions of oxychlorination were optimized to improve the catalyst regeneration effect and operation convenience. The energy consumption problem of condensate circulation between stages was solved by the optimization of compressor interstage flow. The upgrade of regeneration control scheme made the regeneration process simpler, safer and easier to control. The development of coupled energy-saving technology further reduced the energy consumption of the unit. In addition, a series of optimization has been carried out in key equipment such as reactor and heating furnace, plant layout and pipeline stress analysis, so as to improve the performance and safety of large-scale SCCCR unit. This paper summarized the large-scale development of SCCCR unit and provided engineering experience for the design of mega-scale catalytic reforming unit.

STUDY ON ANTI-COKING TECHNOLOGY OF UNCONVERTED OIL FROM EBULLATED-BED RESIDUE HYDROTREATER BY ELECTRIC FIELD PURIFICATION

2023, 54(12):  20-25. 

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The heavy unstable components rich in asphaltene and toluene insoluble matter in unconverted oil from ebullated-bed residue hydrotreater are important factors affecting the secondary processing performance of unconverted oil. Based on the polarity and charged characteristics of these components, a method of electric field treatment was proposed to remove the heavy unstable components rich in asphaltene and coke from the products of ebullated-bed hydrotreater. The effects of temperature, time, and voltage on removing the unstable components in unconverted oil  from ebullated-bed hydrotreater were investigated. The results showed that under the action of an electric field, increasing temperature, time, and voltage were beneficial to the removal of unstable components; the higher the temperature and voltage, and the longer the time, the higher the content of n-heptane insoluble and toluene insoluble in the precipitate, and the less toluene-insoluble matter in the purified oil. Under the test conditions, the maximum precipitation removal rate(mass fraction) reached 1.4%, the maximum removal rate of toluene insoluble matter in the purified oil was 96.32%, and the highest contents of n-heptane insoluble and toluene insoluble in the precipitates reached 54.66% and 51.55%, respectively. Applying the electric field to remove unstable components in the unconverted oil has little effect on the four component composition of the unconverted oil. The removal of unstable components can greatly reduce the coking tendency of unconverted oil.

RESEARCH ON PROCESS CONDITIONS AND COMMERCIAL APPLICATION OF SOLVENT DEASPHALTING DEVICE

2023, 54(12):  26-31. 

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A 1.6 Mt/a solvent deasphalting unit of a certain refining and chemical enterprise has undergone significant changes in the properties of the planned processing stock compared to the original design of the unit. In order to explore suitable process operating conditions and production schemes for the present stock, a pilot study was carried out in cooperation with SINOPEC Research Institute of Petroleum Processing Co., Ltd., the suitable process operating conditions and product utilization scheme were found. After the application of the process conditions in the industrial plant, high-quality light deasphalted oil and heavy deasphalted oil products had be produced successfully. The deasphalted oil was used as a raw material for the secondary processing device, instead of expensive raw materials such as atmospheric residue, in optimizing the production process for the enterprise at same time to create better economic benefits

INDUSTRIAL PRACTICE OF WATER INJECTION TO OVERHEAD OF CRUDE OIL DISTILLATION TOWER

2023, 54(12):  32-38. 

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Overhead water injection, as an important part of the anti-corrosion measures “one removal and three injections” for crude atmospheric and vacuum distillation units, has been promoted and applied in most refineries, and has been summarized and improved in practice, achieving good results. Due to the fact that water injection at the tower overhead can not only change the dew point temperature and increase the stream pH around dew point temperature to alleviate dew point corrosion, but also reduce salt and scale deposition in the system, thereby reducing under-deposit corrosion. In order to ensure the optimal effect of water injection, multiple factors need to be considered, mainly including water quality, injection position, injection volume, etc. Based on analyzing of the factors related to optimizing water injection, combining the industrial practical experience, the best guidance were proposed. Practical case results show that the measures such as optimizing water quality, dynamically adjusting injection volume, and selecting proper injection positions can bring significant economic benefits, improve anti-corrosion effects, and reduce safety hazards.

IMPACT OF START-UP OF EBULLATED-BED RESIDUE HYDROCRACKING UNIT ON VGO HYDROTREATER OPERATION

2023, 54(12):  39-42. 

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After the start-up of ebullated-bed residue hydrocracking (H-oil) unit, the raw materials of solvent deasphalting unit were adjusted from washing oil of vacuum distillate unit and vacuum residue to unconverted oil from H-oil unit, the properties of deasphalted oil（DAO）were changed. Through process optimization, DAO was stopped blending 2.0 Mt/a VGO hydrotreating unit feed, and it was changed into the feed of residue fluid catalytic cracking unit directly. The operating parameters of VGO hydrotreating unit, the properties of feedstocks and products, and the presure difference of the hydrotreating reactor bed were compared and analyzed before and after stopping blending DAO. The results showed that the feedstocks and products properties, impurities such assulfur and nitrogen removal ratesand hydrotreating reactor bed pressure difference were improved significantly when DAO stopping into VGO hydrotreating unit, meanwhile the unit long-term operation length were extended.

APPARENT KINETICS OF COKE COMBUSTION OF COUNTERCURRENT CONTINUOUS REFORMING CATALYST

2023, 54(12):  43-47. 

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A fixed-bed reactor was used for the study of the catalyst in the countercurrent continuous reforming unit under the condition of eliminating the influence of external diffusion, and the effects of reaction temperature, oxygen partial pressure, and carbon content on the coke combustion rate of countercurrent naphtha catalytic reforming catalyst were systematically investigated. The apparent kinetic equation of coke combustion in power series form was established. The results showed that the burning rate increased with the increase of reaction temperature, oxygen partial pressure, and carbon content. The reaction order for oxygen in the kinetic equation is 0.78, the reaction order for carbon is 0.68, and the apparent reaction activation energy is 9.98×10⁴ J/mol. According to the equation, the coke burning rate of catalyst under different conditions could be calculated accurately, and the design parameters and operating conditions of regenerator could be optimized.

MONOTONICALLY INCREASING EXPONENTIAL FUNCTION SPLINE INTERPOLATION METHOD FOR DISTILLATION CURVE OF CRUDE OIL

2023, 54(12):  48-54. 

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When the virtual component method is used to characterize the complex chemical composition of crude oil and its fractions, the distillation curve is often discontinuous and fluctuating, and the reliability of the results is poor because of insufficient distillation data. The traditional quadratic and cubic polynomial spline interpolation functions are commonly used to keep the distillation curve continuous and smooth, but those interpolation results sometimes are not accord with the monotonic increasing characteristics of the distillation curve. An exponential spline interpolation with three parameters was designed to guarantee the monotone increasing of distillation curve in theory. Furthermore, the real boiling point distillation data of 52 kinds of crude oils were interpolated and verified. The results showed that the method of exponential spline interpolation could guarantee the monotone increasing of the distillation curve after interpolation. Among the 52 kinds of interpolation results, there were 37 kinds whose fitting determination coefficient (R²) of exponential spline interpolation was greater than 0.99, accounting for 71.2%, and only 21 kinds whose R² of cubic spline interpolation was greater than 0.99, accounting for 40.4%. There were 50 kinds whose accuracy of exponential spline interpolation was higher than that of cubic spline interpolation, which showed that exponential spline interpolation was better than cubic spline interpolation. Therefore, based on the exponential spline interpolation method, the accuracy of the virtual component method could be obviously improved.

COMMERCIAL APPLICATION OF MULTI-STAGE POROUS MOLECULAR SIEVE CATALYST FOR CATALYTIC CRACKING

2023, 54(12):  55-60. 

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Due to heavy feedstock and increased coke production, the operation of the catalytic cracking unit of CNOOC Dongfang Petrochemical Co., Ltd. was limited. Based on this situation, the company has decided to use OMT-Ⅱ(R), a new generation of multistage porous molecular sieve DCC catalyst with high propylene and ethylene yield, developed by SINOPEC Research Institute of Petroleum Processing Co., Ltd. based on low coke technology platform. The results of commercial application showed that the yields of ethylene, propylene and LPG could be increased 0.44, 1.99 and 5.02 percentage points respectively when the catalyst OMT-II (R) occupied more than 85% of the mass of the system, and the yield of coke was decrease by 0.18 percentage point. At the same time, the yields of gasoline, diesel and oil slurry were decreased significantly.??It has achieved the target of significantly improving the cracking ability of heavy oil, reducing the coke yield, and successfully improving the comprehensive benefit of the DCC unit.

FLEXIBLE DESIGN AND OPTIMIZATION OF REFINERY HYDROGEN NETWORKS UNDER UNCERTAINTIES

2023, 54(12):  61-73. 

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The integrated design and optimization of hydrogen networks is a significant pathway for refineries to achieve energy conservation and carbon emission reduction. However, the long-term operation of hydrogen networks is subject to various uncertain factors such as external market changes, crude feedstock property fluctuations, and operating condition variations, etc. A novel two-stage stochastic programming modeling method based on flexibile design was used to establish a mathematical programming model, which could integrate optimization strategies to deal with the uncertainties in the production process. Then, the mixed-integer nonlinear programming model with a large number of bilinear terms was constructed, a tailored-made global optimization algorithm based on multiparametric disaggregation technique was proposed to accelerate convergence, and a flexible design and optimization case of hydrogen network in a refinery was presented to verify the universality of the model and the efficiency of the algorithm. The results showed that the integrated optimization model could carry out flexible recovery and cascading matching of hydrogen resources among complex hydrogen network structures, and multi-scenario operation strategies could increase the operational flexibility and maximize the economic benefits of the hydrogen network under uncertain environments.

REACTOR MODULE DEVELOPMENT AND FULL PROCESS SIMULATION OF SINOALKY ALKYLATION BASED ON CAPE-OPEN STANDARD

2023, 54(12):  74-82. 

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Based on SINOALKY sulfuric acid alkylation process, a 20-lump reaction kinetics model and a reactor model were established. On the basis, an alkylation reactor module conforming to CAPE-OPEN standard with six material interfaces, a numerical solver and a visual user interface were developed. The reactor module was loaded into Aspen Plus simulation software, and a full process model of a 0.2 Mt/a SINOALKY alkylation unit was built, the simulation effect by the model was good. Furthermore, the effects of reaction parameters on the composition and properties of alkylation products were investigated. The results showed that the model simulation values were in accordance with the actual alkylation process, and the full process model including the SINOALKY alkylation reactor module could give important reference for the simulation and optimization of SINOALKY alkylation unit.

SIMULATION ON COKE POWDER REMOVAL BY MULTI-SPRAY IN COKING FRACTIONATOR

2023, 54(12):  83-89. 

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In view of the poor removal effect of coke powder by the traditional herringbone baffle in the desuperheating section of coking fractionator of delayed coking unit, which results in a large amount of coke powder entering into coking gas oil and coking diesel oil, resulting in unqualified products, water-air-coke powder and coking gas oil-oil-gas-coke powder systems were used to simulate the removal of oil-gas coke powder by spraying water and oil droplets with three sprinklers respectively. The results showed that the best arrangement of the three sprinklers was the triangle with the ratio of the distance between the sprinkler and the column center（r） and the column radius（R）of 0.56. Under the conditions of the liquid spray density of 2 m³/(m²·h) and the high gas load, the coke removal rate of single-layer multi-nozzle single-way (S-T-S) spray water droplets was about 3% higher than that of single-layer single-nozzle single-way (S-S-S) spray water droplets, and the average coke removal rate of S-T-S and S-S-S spray oil droplets was more than 98.4%. The minimum coke removal rates of S-T-S spray and S-S-S spray oil droplets were 10.57% and 11.43% higher than those of corresponding spray water droplets, respectively, which indicated that the effect of removing coke powder by spray oil drop washing was better than that by spray water drop washing. The results of commercial application showed that the product quality of side-line of coking fractionator could be improved obviously by using the multi nozzle spray oil droplet technology.

MOLECULAR DYNAMICS SIMULATION AND EXPERIMENTAL SYNTHESIS OF OIL-SOLUBLE VISCOSITY REDUCER

2023, 54(12):  90-99. 

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In order to reduce the viscosity and improve the fluidity of heavyoil,molecular dynamics simulation combined with orthogonal test was carried out.Octadecyl methacrylate(SMA),N-phenylmaleimide（N-PMI) and vinylacetate (VA) were used as monomers,and oil-soluble viscosity reducer(SNV) was synthesized by copolymerization.The simulation results showed that the density of heavy oil decreased and the potential energy increased after adding SNV,which means that SNV could destroy the three-dimensional network structure between resins and asphaltenes,and inhibit the association of resins and asphaltenes.The test results showed that the optimum synthesis conditions of SNV were as follows:monomer molar ratio of SMA,N-PMI,VA of 10∶1∶6, initiator amount of 0.5%,reaction time of 6h and reaction temperature of 50 ℃.Under this synthetic condition,the viscosity reduction rate of heavy oil could reach 43.76%,which was better than some commerciall viscosity reducer.The molecular dynamics simulation results were consistent with the test results.

SYNTHESIS OF POLYETHER IMIDAZOLINE FLOCCULANTS AND EVALUATION OF DESOLIDIFICATION PERFORMANCE

2023, 54(12):  100-105. 

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With the development of the trend of "oil refining to chemicals", the technology of producing chemicals directly from crude oil is gradually replacing catalytic cracking technology, but it produces the slurry containing alkaline catalyst, which makes the existing settling agent unable to effectively remove solid particles from the oil slurry containing alkaline catalyst. The polyether-imidazoline flocculants were synthesized by introducing carboxyl groups and imidazoline structure into the main chain of polyether, and the structures of the products were characterized by nuclear magnetic resonance spectroscopy and infrared spectroscopy. The structure-activity relationship of polyether-imidazoline flocculant and the desolidification performance were investigated by oil slurry settling test. The optimal settling conditions were determined as follows: mass fraction of the main agent of 40% , the dosage of 400 μg/g,  settling temperature of 100 ℃ and settling time of 48 h, and slurry desolidification rate was grater than 90%. The flocculant synthesis method was safe, the compounding conditions were simple, the raw material was cheap and easy to obtain, and the flocculant was suitable for industrial production and application.

DETERMINATION METHODS OF CETANE NUMBER IN DIESEL AND COMPARISON OF THEIR RESULTS

2023, 54(12):  106-113. 

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Cetane number is the key index to measure the ignition of diesel fuel, which reflects the combustion characteristics of diesel in engine. At present, the test methods of measuring cetane number of diesel are mainly divided into engine direct test method and constant volume combustion simulation method, each of which includes several test methods. In this paper, the test characteristics of each method were compared from the principle and precision of the method, the comparison tests of various cetane number test methods were carried out, and the advantages and disadvantages and applicability of each method were summarized. Finally, the existing problems in the field of cetane number testing were summarized and the future development direction was prospected.

STUDY ON CORROSION PROPERTIES OF ALUMINIUM SOL BASED ON WEIGHT LOSS METHOD

2023, 54(12):  114-118. 

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During the preparation of catalysts for catalytic cracking, methanol-to-olefin,etc.,aluminum sol solution as a binder will cause corrosion to equipment, so it is necessary to measure the performance of aluminum sol and its corrosion rate to industrial equipment. At present, there are some problems in the commercial corrosion performance evaluation instrument, such as speed distortion, temperature delay inaccuracy, cavitation effect affecting the experimental data and so on, which affect the accuracy of the test data. In order to solve the problems faced by the industry, a new type of four-channel high efficiency alumina sol corrosion evaluation instrument was developed based on weight loss method, and some key technologies such as pumping aluminum sol liquid, in-situ heating and temperature control were used to ensure that there was no significant temperature gradient in the test system. The test results showed that the maximum relative error of corrosion rate of 20# carbon steel coupons in optimum?condition from the apparatus was only 2.3%, and repeatability was good. The effects of velocity gradient on corrosion efficiency of aluminum sol were investigated by CFD numerical simulation. A formula which could predict the corrosion rate was established, which provided the test data and model support for the corrosion protection of industrial equipment.

RESEARCH ON CORROSION AND SCALING PREDICTION MODLE FOR CYCLE-COOLING WATER SYSTEM IN PETROCHEMICAL ENTERPRISES

2023, 54(12):  119-126. 

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Based on the operating data from the cycle-cooling water system of a petrochemical enterprise, 899 sets of valid data samples were obtained by data preprocessing; the input variables for corrosion rate prediction (FSSL) model and adhesion rate prediction (NFSL) model were selected by using maximum mutual information coefficient and Pearson correlation coefficient methods. With 3 machine learning algorithms including BP neural network, KNN regression, and XGBoost, the prediction models for FSSL and NFSL of the cycle-cooling water system were established respectively. The evaluation results of the prediction accuracy and warning effectiveness of three models showed that the average relative error of the all three models was below 9%, and the three models had good fitting effect and generalization ability. The model based on XGBoost method had the best performance, the average relative error for both FSSL and NFSL was less than 5%, the decision coefficient R² was over 0.9, and the early warning accuracy was over 91.5% and 97.3% respectively.

DESIGN OPTIMIZATION AND APPLICATION PERFORMANCE OF ELECTROSTATIC ADSORPTIVE OIL PURIFICATION REACTOR

2023, 54(12):  127-134. 

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In order to solve the problem of performance degradation of transformer oil due to external factors during operation, based on the principle of electrostatic adsorption, Ansoft Maxwell finite element simulation software was used to construct gradient non-uniform electric field on the "wave"-type curved pole plate. The movement law and pattern of electrically neutral impurities and charged impurities in the gradient non-uniform field in the transformer oil was investigated. On this basis, an orthogonal test scheme was designed to test the effect of the electrostatic adsorption reactor on oil quality, and the working conditions of the oil purification reactor were optimized. The results showed that the optimum working conditions of the electrostatic adsorption reactor were as follows: voltage 12 kV, temperature 45 ℃, flow rate 0.10 m/s. After purification treatment by the reactor, the dielectric loss factor of transformer oil reduced from 0.042 58 to 0.003 76, which indicated that the developed oil purification reactor could effectively improve the quality of aging transformer oil

ANALYSIS OF INFLUENCING FACTORS ON NH₄Cl CRYSTALLIZATION AND PREDICTION OF DEPOSITIVE CHARACTERISTICS IN RESIDUAL OIL HYDROGENATION AIR COOLER

2023, 54(12):  135-142. 

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With the depletion of crude oil resources, a large number of highly corrosive inferior crude oils are refined in China. Among them, ammonium salt corrosion risk of cold exchange equipment is high due to strong corrosiveness of raw material and long-term extreme operating conditions of equipment. In this paper, the air cooler of the fluidized bed residue hydrogenation system was taken as the research object, and NRTL-RK model was used to construct the chemical ion-equilibrium model of the reaction effluent system under the multi-component system. Through the process correlation analysis and numerical simulation analysis, the risk of ammonium salt crystallization corrosion in the system was evaluated. The process calculation results showed that there was corrosion risk of ammonium chloride in the air cooler of the system, the crystallization temperature was 169-187 ℃, and the crystallization rate of ammonium salt increased continuously with the decrease of temperature, the limit operating condition was 0.22 kg/h. The convection heat transfer model of air cooler was constructed by component transport equation and condensation model. The numerical simulation results showed that the maximum mass transfer coefficient (1.52×10^-4 m/s) and corrosion rate (0.43 mm/a) occurred at the bottom of the outlet manifold.

REVIEWS ON SYNTHESIS TECHNOLOGIES OF 1,2-PROPANEDIOL

2023, 54(12):  143-148. 

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The synthesis of 1,2-propanediol by hydration of propylene oxide, transesterification, hydrogenolysis of glycerol, and reaction of propylene hydrogen with peroxide were introduced and compared. Propylene catalytic oxidation technology has the characteristics of low cost and easy availability of raw materials, integration of two reactions in one reactor, higher yield of 1,2-propanediol, no need to invest in propylene oxide production capacity, and good technical and economic efficiency, which can realize the cleaner production of 1,2-propanediol, and has a good prospect of industrial application. It was suggested that the development of stable and efficient catalytic oxidation catalyst should be the key research direction of this technology in the future.