Silicon-containing aryl acetylene resin(PSA)is a new type of high-temperature resistant resin with excellent oxidation resistance,whereas antioxidant reaction mechanism of PSA resin under ultra-high temperatures still...Silicon-containing aryl acetylene resin(PSA)is a new type of high-temperature resistant resin with excellent oxidation resistance,whereas antioxidant reaction mechanism of PSA resin under ultra-high temperatures still remains unclear.Herein,the oxidation behavior and mechanisms of PSA resin are systematically investigated combining kinetic analysis and Reax FF molecular dynamics(MD)simulations.Thermogravimetric analysis indicates that the oxidation process of PSA resin undergoes two main steps:oxidative mass gain and oxidative degradation.The distributed activation energy model(DAEM)is employed for describing oxidation processes and the best-fit one is obtained using genetic algorithms and differential evolution.DAEM model demonstrates that the oxidative weight gain stage is dominated by two virtual reactants and the oxidative degradation stage consists of three virtual reactants.Correspondingly,the observation of MD reaction pathways indicates that oxygen oxidation of unsaturated structures occurs in the initial stage,which results in the formation of PSA resin oxides.Furthermore,cracked pieces react with O_(2)to generate CO and other chemicals in the second step.The resin matrix's great antioxidation resilience is illustrated by the formation of SiO_(2).The analysis based on MD simulations exhibits an efficient computational proof with the experiments and DAEM methods.Based on the results,a two-stage reaction mechanism is proposed,which provides important theoretical support for the subsequent study of the oxidation behavior of silica-based resins.展开更多
This study focuses on CO_(2) capture by pressure swing adsorption(PSA),with modified clinoptilolite as the adsorbent.Natural clinoptilolite is modified by roasting,by acid pickling,by a combination of acid pickling an...This study focuses on CO_(2) capture by pressure swing adsorption(PSA),with modified clinoptilolite as the adsorbent.Natural clinoptilolite is modified by roasting,by acid pickling,by a combination of acid pickling and roasting,and by ion exchange.Modification by acid pickling-roasting and by ion exchange are found to give the highest CO_(2) adsorption capacities,of 730 mL/g and 876.7 mL/g,respectively.It is found that regeneration of clinoptilolite by a combination of vacuum desorption and heating enables recovery of as much as 89%of its previous CO_(2) adsorption capacity.To examine the CO_(2) adsorption capacity of clinoptilolite when applied to mixed gas,a simulated coking exhaust containing 12%CO_(2) and 4%O_(2) is used,and it is found that ion exchange modified clinoptilolite achieves a CO_(2) removal efficiency of 92.5%.A BET test reveals that acid pickling-roasting and Na^(+) modification enhance the porosity of clinoptilolite,thereby improving its adsorption capacity.This work demonstrates the feasibility of applying modified clinoptilolite as an effective adsorbent for COO_(2)capture,providing a promising tool for dealing with greenhouse gases.展开更多
基金financially supported by National Natural Science Foundation of China(22008073,22078100,21878091)Shanghai Sailing Program(20YF1410600)。
文摘Silicon-containing aryl acetylene resin(PSA)is a new type of high-temperature resistant resin with excellent oxidation resistance,whereas antioxidant reaction mechanism of PSA resin under ultra-high temperatures still remains unclear.Herein,the oxidation behavior and mechanisms of PSA resin are systematically investigated combining kinetic analysis and Reax FF molecular dynamics(MD)simulations.Thermogravimetric analysis indicates that the oxidation process of PSA resin undergoes two main steps:oxidative mass gain and oxidative degradation.The distributed activation energy model(DAEM)is employed for describing oxidation processes and the best-fit one is obtained using genetic algorithms and differential evolution.DAEM model demonstrates that the oxidative weight gain stage is dominated by two virtual reactants and the oxidative degradation stage consists of three virtual reactants.Correspondingly,the observation of MD reaction pathways indicates that oxygen oxidation of unsaturated structures occurs in the initial stage,which results in the formation of PSA resin oxides.Furthermore,cracked pieces react with O_(2)to generate CO and other chemicals in the second step.The resin matrix's great antioxidation resilience is illustrated by the formation of SiO_(2).The analysis based on MD simulations exhibits an efficient computational proof with the experiments and DAEM methods.Based on the results,a two-stage reaction mechanism is proposed,which provides important theoretical support for the subsequent study of the oxidation behavior of silica-based resins.
基金supported by the Natural Science Foundation of China(42177359)the Open Fund of the National Engineering Laboratory for Site Remediation Technologies(NEL-SRT201907).
文摘This study focuses on CO_(2) capture by pressure swing adsorption(PSA),with modified clinoptilolite as the adsorbent.Natural clinoptilolite is modified by roasting,by acid pickling,by a combination of acid pickling and roasting,and by ion exchange.Modification by acid pickling-roasting and by ion exchange are found to give the highest CO_(2) adsorption capacities,of 730 mL/g and 876.7 mL/g,respectively.It is found that regeneration of clinoptilolite by a combination of vacuum desorption and heating enables recovery of as much as 89%of its previous CO_(2) adsorption capacity.To examine the CO_(2) adsorption capacity of clinoptilolite when applied to mixed gas,a simulated coking exhaust containing 12%CO_(2) and 4%O_(2) is used,and it is found that ion exchange modified clinoptilolite achieves a CO_(2) removal efficiency of 92.5%.A BET test reveals that acid pickling-roasting and Na^(+) modification enhance the porosity of clinoptilolite,thereby improving its adsorption capacity.This work demonstrates the feasibility of applying modified clinoptilolite as an effective adsorbent for COO_(2)capture,providing a promising tool for dealing with greenhouse gases.
