Three-dimensional Ordered Macropore Catalytic Cracking Of Waste Plastics To Prepare Asphalt Warming Agent

In recent years,China’s basic road construction has developed rapidly.In asphalt pavement construction,the traditional hot mix asphalt mixture（HMA）technology has defects such as high construction temperature,large energy consumption,and serious pollutant gas emissions.WMA)technology can solve such problems.At the same time,with the rapid development of China’s industry and agriculture,the output of plastics has increased dramatically,and the resulting waste plastics have caused a serious burden on the ecological environment.The resource utilization technology is an effective means to solve the pollution of waste plastics.This technology is the process of converting waste plastics into fuel oil,paraffin and other high value-added chemicals through thermal cracking or catalytic cracking.Polymer wax has a viscosity-reducing effect on asphalt and can be used as a warm asphalt mixing agent.Therefore,it is obviously feasible to prepare wax warm mixing agent by cracking waste plastics.Although related research has been carried out,there are few studies on the catalytic cracking of waste agricultural film plastics（mainly linear low-density polyethylene）by catalytic cracking.The design of related catalysts and the performance of cracked wax modified asphalt still need to be further developed.Based on the above discussion,this paper uses linear low-density polyethylene（LLDPE）as the raw material and acidic three-dimensional ordered macroporous SiO₂（3DOMSiO₂）as the catalyst to prepare polyethylene wax（PEW）by thermal cracking and catalytic cracking methods.The effect of cracking method on the properties of PEW was analyzed,and the modification performance of different PEW on asphalt was investigated.The specific research contents are as follows:（1）Research on the performance of thermal cracking LLDPE wax:using thermal cracking method to crack LLDPE in a pressure reactor to prepare cracking wax（PE Wax,referred to as PEW）,and compare and confirm the performance of PEW through yield,molecular weight and dropping melting point The best lysis conditions.Studies have shown that the thermal cracking method can be used to crack LLDPE into PEW with excellent performance.The cracking temperature and time are the main factors affecting the performance of PEW.The optimal cracking temperature is 260℃and the optimal cracking time is 15～60 min.（2）Synthesis of 3DOMSiO₂catalyst:The colloidal crystal template method was used to synthesize and acidify 3DOMSiO₂,and the catalyst was characterized by XRD and SEM.The results prove that the synthesized 3DOMSiO₂is an amorphous macroporous structure with an average pore diameter of 600 nm and IUPAC typeⅡadsorption characteristics.（3）Research on the performance of catalytic cracking of LLDPE wax:Based on the results of thermal cracking research,using 3DOMSiO₂as a catalyst,the catalytic cracking method was used to crack LLDPE in a pressure reactor to prepare PEW.Studies have shown that the best catalyst for the production of PEW by catalytic cracking method is 3DOMSi-15,and the optimal dosage is 0.3%;in addition,when the properties of the obtained PEW are the same,the temperature required for catalytic cracking is reduced by 20℃and the time is shortened by 10min compared to thermal cracking,Activation energy decreased by 39.85k J/mol.（4）Research on the performance of PEW modified asphalt:three experiments of asphalt,viscosity and other experiments were used to verify the warm mixing effect of different PEW,analyze the performance of modified asphalt and screen out the best warm mixing agent;Add 70#matrix asphalt with different blending ratios,analyze and compare the performance of various blended modified asphalts and screen out the best blending quantity;perform comprehensive comparison with commercial warm mixes（Sasobit,Evertherm-DAT）to analyze PEW warm mix The practical and development possibilities of the agent.The study found that PEW-2 has the best warm mixing effect and good overall performance at 6%dosage.Compared with the base asphalt,the viscosity is reduced by 35%,the penetration is increased by 0.1mm,the softening point is increased by 27.8%,and the ductility is slightly There is a reduction,and the dispersion and spatial structure are better.In addition,PEW has better comprehensive performance and economic benefits than Sasobit and Evertherm-DAT warm mix.