Regeneration Of Coking Inactivation HZSM-5 By DNTP And Online Catalytic Upgrading Of Bio-oil

Recently,the shortage of fossil energy and environmental pollution have become increasingly serious,which has attracted global attention.The use of catalytic pyrolysis methods to convert biomass into valuable fuels to partially replace fossil energy sources can effectively alleviate my country’s energy and environmental problems.HZSM-5 is prone to coking and deactivation in the process of biomass pyrolysis and catalysis.Hydrogenation,gasification and oxidation regeneration are easy to destroy the skeleton structure of HZSM-5,and the regeneration reaction speed of low temperature plasma injection（NTPI）is slow,and it is difficult to penetrate into the interior of HZSM-5.Therefore,the direct low temperature plasma（DNTP）regeneration method is used to regenerate the deactivated HZSM-5.First,using rape straw as the raw material and HZSM-5 as the catalyst,the biomass pyrolysis catalysis experiment was carried out to explore the changes of HZSM-5 coke deposition and surface groups;HZSM-5 with deactivated coke was used for DNTP regeneration and the regeneration voltage was explored Change the structure and performance of HZSM-5;then,regenerate HZSM-5 with different coke deposits to explore the regeneration effect of HZSM-5 under different working conditions;additional DNTP treatment of fresh HZSM-5 test,comparison regeneration test,Explore the effect of DNTP treatment on the pore structure and acidity of fresh HZSM-5;finally,apply the HZSM-5 after each group of DNTP treatments to the biomass catalytic pyrolysis test,and explore the changes in the catalytic performance of the HZSM-5 after each group of treatments.A regeneration-recycling method is used to determine the service life of the catalyst.The main research contents are as follows:（1）Using biomass as a raw material and HZSM-5 as a catalyst,a biomass pyrolysis catalysis test was carried out,and deactivated HZSM-5 with different coke deposits was obtained.The regeneration voltage of DNTP was changed to obtain HZSM-5 after regeneration at different voltages.TG,SEM,TEM,BET and NH₃-TPD were used to analyze the physical and chemical characteristics of the regenerated catalysts.Use OES monitoring to detect the energy level transitions of O atoms and O ions in the DNTP reaction zone through OES,and explore the reaction mechanism of DNTP regeneration.Finally,the catalysts used for each duration are regenerated to explore the effectiveness of DNTP regeneration.The results show that when the oxygen flow rate is 4 L/min,the discharge frequency is 18 k Hz,the DNTP reactor has better working performance;Compared with other regenerative voltages,HZSM-5,which is coked and deactivated at 22 k V,has the best regeneration effect,and the residual of R-22 The amount of carbon deposit is 1.99%.The specific surface area,total pore volume and total acid increase of the catalyst are the largest,reaching the maximum values of 340.72 m²·g^-1,0.36 cm³·g^-1 and 1.75 m L·g^-1,and the surface particles of the catalyst are relatively large.It is small,and a small amount of mesoporous structure appears;from OES analysis,it can be found that this change of the catalyst comes from the micro-discharge effect generated during the transition of O ion,which modifies the pore structure and acid content.When the regeneration voltage rises to 26 k V,the high voltage causes breakdown of the catalyst at this time,so the regeneration effect of the catalyst decreases.HZSM-5 with a coke deposition amount of 3.18%,4.08%,and 7.60%has more significant decarbonization effects.（2）Using fresh HZSM-5 as raw material,changing the voltage of DNTP modification to obtain modified HZSM-5 with different voltages,and characterizing the modified HZSM-5,using TG,SEM,TEM,BET and NH₃-TPD to the physical and chemical properties of the modified HZSM-5 of each group were analyzed.The energy level transitions of O atoms and O ions in the DNTP reaction zone were detected by OES,and the mechanism of DNTP modification was explored.The results show that the discharge voltage can effectively modify the catalyst,but the voltage intensity needs to be controlled.If the voltage is too high,HZSM-5 will be directly broken down;Compared with other regeneration voltages,the catalyst’s specific surface area,total pore volume and acid content increase the most at 22 k V,reached peaks of 287.34 m²·g^-1,0.24 cm³·g^-1and 1.65 m L·g^-1,there are many dense holes in the center,and the degree of stacking of the surface layer decreases;from the OES analysis,it can be found that the modification effect comes from the high electric field in the DNTP reaction zone is accompanied by the micro-discharge effect of O ions;when the voltage rises to 24 k V,the high electric field energy produces too many O ions transitions,causing the catalyst breakdown to come early,reducing the catalyst modification effect.（3）Carry out biomass pyrolysis catalysis test using HZSM-5 after each group of DNTP treatment,and record the product yield of each phase in the test.GC-MS was used to characterize the organic phase of bio-oil,and the catalytic performance of each group of HZSM-5 was analyzed.At the same time,the cycle regeneration is used to test the influence of DNTP on the lifespan of HZSM-5.The results show that among the regenerated catalysts,R-22 has the best catalytic performance,and the relative peak area ratios of the ideal product monocyclic aromatic hydrocarbons and total hydrocarbons reach 46.93%and 53.62%;in the bio-oil prepared by the catalyst after 3 regeneration cycles the relative peak area ratio of hydrocarbons can reach 94.5%of the original amount.Among the modified catalysts,F-22 has the best catalytic performance.The ideal product monocyclic aromatic hydrocarbons and total hydrocarbons account for 40.55%and 51.52%,the output of oxygen-containing compounds such as acids and carbonyl compounds in the organic phase is significantly reduced.After 16 cycles of recycling,the relative peak area ratio of the hydrocarbons in the bio-oil can still reach 71.11%of the original amount,and the service life can reach more than 480 min.The new DNTP regeneration method developed in this subject shows good regeneration performance,which has important practical significance for improving the efficiency of biomass pyrolysis and reducing the energy consumption of pyrolysis.