A non-phosgene route for the synthesis of hexamethylene-1,6-diisocyanate(HDI) was developed via catalytic decomposition of hexamethylene-1,6-dicarbamate(HDC) over Zn–Co bi-metallic supported ZSM-5 catalyst.The cataly...A non-phosgene route for the synthesis of hexamethylene-1,6-diisocyanate(HDI) was developed via catalytic decomposition of hexamethylene-1,6-dicarbamate(HDC) over Zn–Co bi-metallic supported ZSM-5 catalyst.The catalyst was characterized by FTIR and XRD analyses. Three solvents dioctyl sebacate(DOS), dibutyl sebacate(DBS) and 1-butyl-3-methylimidazolium tetrafluoroborate(BMIMBF_4) were investigated and compared; DOS gave better performance. The catalytic performances for thermal decomposition of HDC to HDI using DOS as solvent were then investigated, and the results showed that, under the optimized reaction conditions, i.e.,10 wt%concentration of HDC in DOS, 250 °C temperature, 60 min reaction time, 83.8% yield of HDI had been achieved over Zn–Co/ZSM-5. Decomposition of the intermediate hexamethylene-1-carbamate-6-isocyanate(HMI) over Zn–Co/ZSM-5 in DOS solvent was further studied and the results indicated that yield of HDI from HMI reached to 69.6%(98.6% HDI selectively) at 270 °C, which further increased the yield of the total HDI(HDI_(tol)) to as high as 95.0%. Recycling of catalyst showed that HDI and HMI yield slightly decreased, and by-product yield increased after the catalyst was reused for 4 times. At last possible reaction mechanism was proposed.展开更多
The utilization of CO_2 as raw material for chemical synthesis has the potential for substantial economic and green benefits. Thermal decomposition of hexamethylene-1,6-dicarbamate(HDC) is a promising approach for ind...The utilization of CO_2 as raw material for chemical synthesis has the potential for substantial economic and green benefits. Thermal decomposition of hexamethylene-1,6-dicarbamate(HDC) is a promising approach for indirect utilization of CO_2 to produce hexamethylene-1,6-diisocyanate(HDI). In this work, a green route was developed for the synthesis of HDI by thermal decomposition of HDC over Co_3O_4/ZSM-5 catalyst, using chlorobenzene as low boiling point solvent. Different metal oxide supported catalysts were prepared by incipient wetness impregnation(IWI), PEG-additive(PEG) and deposition precipitation with ammonia evaporation(DP) methods. Their catalytic performances for the thermal decomposition of HDC were tested. The catalyst screening results showed that Co_3O_4/ZSM-5_(25) catalysts prepared by different methods showed different performances in the order of Co_3O_4/ZSM-5_(25)(PEG)N Co_3O_4/ZSM-5_(25)(IWI)N Co_3O_4/ZSM-5_(25)(DP). The physicochemical properties of Co_3O_4/ZSM-5_(25) catalyst were characterized by XRD, FTIR, N2 adsorption-desorption measurements, NH3-TPD and XPS.The superior catalytic performance of Co_3O_4/ZSM-5_(25)(PEG)catalyst was attributed to its relative surface content of Co^(3+), surface lattice oxygen content and total acidity. Under the optimized reaction conditions: 6.5% HDC concentration in chlorobenzene, 1 wt% Co_3O_4/ZSM-5_(25)(PEG)catalyst, 250 °C temperature, 2.5 h time, 800 ml·min-1 nitrogen flow rate and 1.0 MPa pressure, the HDC conversion and HDI yield could reach 100% and 92.8%respectively. The Co_3O_4/ZSM-5_(25)(PEG)catalyst could be facilely separated from the reaction mixture, and reused without degradation in catalytic performance. Furthermore, a possible reaction mechanism was proposed based on the physicochemical properties of the Co_3O_4/ZSM-5_(25) catalysts.展开更多
基金Supported by the National Natural Science Foundation of China(21476244,21406245)Transformational Technologies for Clean Energy and Demonstration,Strategic Priority Research Program of the Chinese Academy of Sciences,(XDA 21030600)the Youth Innovation Promotion Association CAS(2016046)
文摘A non-phosgene route for the synthesis of hexamethylene-1,6-diisocyanate(HDI) was developed via catalytic decomposition of hexamethylene-1,6-dicarbamate(HDC) over Zn–Co bi-metallic supported ZSM-5 catalyst.The catalyst was characterized by FTIR and XRD analyses. Three solvents dioctyl sebacate(DOS), dibutyl sebacate(DBS) and 1-butyl-3-methylimidazolium tetrafluoroborate(BMIMBF_4) were investigated and compared; DOS gave better performance. The catalytic performances for thermal decomposition of HDC to HDI using DOS as solvent were then investigated, and the results showed that, under the optimized reaction conditions, i.e.,10 wt%concentration of HDC in DOS, 250 °C temperature, 60 min reaction time, 83.8% yield of HDI had been achieved over Zn–Co/ZSM-5. Decomposition of the intermediate hexamethylene-1-carbamate-6-isocyanate(HMI) over Zn–Co/ZSM-5 in DOS solvent was further studied and the results indicated that yield of HDI from HMI reached to 69.6%(98.6% HDI selectively) at 270 °C, which further increased the yield of the total HDI(HDI_(tol)) to as high as 95.0%. Recycling of catalyst showed that HDI and HMI yield slightly decreased, and by-product yield increased after the catalyst was reused for 4 times. At last possible reaction mechanism was proposed.
基金National Natural Science Foundation of China(21476244 and 21406245)Youth Innovation Promotion Association CAS
文摘The utilization of CO_2 as raw material for chemical synthesis has the potential for substantial economic and green benefits. Thermal decomposition of hexamethylene-1,6-dicarbamate(HDC) is a promising approach for indirect utilization of CO_2 to produce hexamethylene-1,6-diisocyanate(HDI). In this work, a green route was developed for the synthesis of HDI by thermal decomposition of HDC over Co_3O_4/ZSM-5 catalyst, using chlorobenzene as low boiling point solvent. Different metal oxide supported catalysts were prepared by incipient wetness impregnation(IWI), PEG-additive(PEG) and deposition precipitation with ammonia evaporation(DP) methods. Their catalytic performances for the thermal decomposition of HDC were tested. The catalyst screening results showed that Co_3O_4/ZSM-5_(25) catalysts prepared by different methods showed different performances in the order of Co_3O_4/ZSM-5_(25)(PEG)N Co_3O_4/ZSM-5_(25)(IWI)N Co_3O_4/ZSM-5_(25)(DP). The physicochemical properties of Co_3O_4/ZSM-5_(25) catalyst were characterized by XRD, FTIR, N2 adsorption-desorption measurements, NH3-TPD and XPS.The superior catalytic performance of Co_3O_4/ZSM-5_(25)(PEG)catalyst was attributed to its relative surface content of Co^(3+), surface lattice oxygen content and total acidity. Under the optimized reaction conditions: 6.5% HDC concentration in chlorobenzene, 1 wt% Co_3O_4/ZSM-5_(25)(PEG)catalyst, 250 °C temperature, 2.5 h time, 800 ml·min-1 nitrogen flow rate and 1.0 MPa pressure, the HDC conversion and HDI yield could reach 100% and 92.8%respectively. The Co_3O_4/ZSM-5_(25)(PEG)catalyst could be facilely separated from the reaction mixture, and reused without degradation in catalytic performance. Furthermore, a possible reaction mechanism was proposed based on the physicochemical properties of the Co_3O_4/ZSM-5_(25) catalysts.
文摘目的检测子痫前期孕妇血清中人端粒酶反转录酶(human telomerase reverse transcriptase,hTERT)、沉默信息调节因子6(silent information regulator 6,Sirt6)表达,并探究hTERT,Sirt6水平表达与疾病严重程度及妊娠结局评估中的价值。方法选取2018年1月~2022年12月在陕西省人民医院进行诊治的300例子痫前期孕妇作为子痫前期组,孕妇均符合《妊娠期高血压疾病诊治指南(2015)》中子痫前期诊断标准,选取同时期孕检的300例健康孕妇为对照组,根据病情严重程度将子痫前期组分为轻症子痫前期组(n=180)和重症子痫前期组(n=120),根据是否发生不良妊娠结局将子痫前期组分为正常妊娠组(n=165)和不良妊娠组(n=135)。酶联免疫吸附实验(enzyme-linked immunosorbnent assay,ELISA)法检测血清中hTERT和Sirt6水平,Spearman相关性分析血清中hTERT和Sirt6水平与子痫前期孕妇病情严重程度的相关性,利用受试者工作特征(receiver operating characteristic,ROC)曲线评估血清hTERT和Sirt6水平在子痫前期诊断及妊娠结局预测中的价值。结果与对照组比较,子痫前期组血清hTERT(22.15±5.82 ng/ml vs 30.12±9.56 ng/ml),Sirt6(5.26±1.62 ng/ml vs 7.06±2.29 ng/ml)水平降低,差异具有统计学意义(t=12.334,11.114,均P<0.001)。与轻症子痫前期组比较,重症子痫前期组孕妇血清hTERT(18.28±4.11 ng/ml vs 24.73±6.96 ng/ml),Sirt6(4.03±1.17 ng/ml vs 6.08±1.92 ng/ml)水平降低,差异具有统计学意义(t=9.142,10.469,均P<0.001)。与正常妊娠组比较,不良妊娠组子痫前期孕妇血清中hTERT(17.75±4.61 ng/ml vs 25.75±6.81 ng/ml),Sirt6(4.06±0.96 ng/ml vs 6.24±2.16 ng/ml)水平降低,差异具有统计学意义(t=11.639,10.878,均P<0.001)。Spearman相关性分析显示,血清hTERT,Sirt6水平与子痫前期孕妇疾病严重程度均呈负相关(r=-0.562,-0.604,均P<0.001)。ROC曲线分析结果显示,血清hTERT,Sirt6诊断子痫前期的曲线下面积(95%置信区间)[AUC(95%CI)]分别为0.711(0.673~0.747),0.727(0.689~0.762),两者联合诊断子痫前期的AUC(95%CI)为0.788(0.753~0.820),高于两者单独诊断(Z=2.719,2.154,P=0.007,0.031);血清hTERT,Sirt6预测子痫前期不良妊娠结局的AUC(95%CI)分别为0.786(0.735~0.831),0.783(0.732~0.829),两者联合预测子痫前期不良妊娠结局的AUC(95%CI)为0.849(0.804~0.888),高于两者单独预测(Z=1.855,1.861,P=0.032,0.031)。结论hTERT和Sirt6在子痫前期孕妇血清中水平较低,与子痫前期孕妇疾病严重程度均呈负相关,并对妊娠结局具有一定的评估价值。