The directly selective hydrogenolysis of xylitol to ethylene glycol(EG) and 1,2-propylene glycol(1,2-PDO)was performed on Cu–Ni–ZrO_2 catalysts prepared by a co-precipitation method. Upon optimizing the reaction con...The directly selective hydrogenolysis of xylitol to ethylene glycol(EG) and 1,2-propylene glycol(1,2-PDO)was performed on Cu–Ni–ZrO_2 catalysts prepared by a co-precipitation method. Upon optimizing the reaction conditions(518 K, 4.0 MPaH_2 and 3 h), 97.0% conversion of xylitol and 63.1% yield of glycols were obtained in water without extra inorganic base. The catalyst still remained stable activity after six cycles and above 80% total selectivity of glycols was obtained when using 20.0% xylitol concentration. XRD, TEM and ICP results indicated that Cu–Ni–ZrO_2 catalysts possess favorable stability. Cu and Ni are beneficial to the cleavage of C–O and C–H bond, respectively. To reduce the hydrogen consumption, isopropanol was added as in-situ hydrogen source and 96.4% conversion of xylitol with 43.6% yield of glycols were realized.展开更多
In the present work, the effects of Ni atoms and vacancy concentrations （0.1%, 0.5%, 1.0%） on the formation process of Cu solute clusters are investigated for Fe-1.24%Cu-0.62%Ni alloys by molecular dynamics （MD） s...In the present work, the effects of Ni atoms and vacancy concentrations （0.1%, 0.5%, 1.0%） on the formation process of Cu solute clusters are investigated for Fe-1.24%Cu-0.62%Ni alloys by molecular dynamics （MD） simulations. The presence of Ni is beneficial to the nucleation of Cu precipitates and has little effect on coarsening rate in the later stage of aging. This result is caused by reducing the diffusion coefficient of Cu clusters and the dynamic migration of Ni atoms. Additionally, there are little effects of Ni on Cu precipitates as the vacancy concentration reaches up to 1.0%, thereby explaining the embrittlement for reactor pressure vessel （RPV） steel. As a result, the findings can hopefully provide the important information about the essential mechanism of Cu cluster formation and a better understanding of ageing phenomenon of RPV steel. Furthermore, these original results are analyzed with a simple model of Cu diffusion, which suggests that the same behavior could be observed in Cu-containing alloys.展开更多
纳米材料因其自身独特性能而备受关注,从而引发了人们对其进行一系列的研究。采用机械合金化法(MA)和粉末冶金法(PM)制备了纳米尺寸和常规尺寸粉末,通过控制温度和压力等因素,利用真空热压烧结炉将两种不同尺寸的Cu-20Co-20Cr-20Ni粉末...纳米材料因其自身独特性能而备受关注,从而引发了人们对其进行一系列的研究。采用机械合金化法(MA)和粉末冶金法(PM)制备了纳米尺寸和常规尺寸粉末,通过控制温度和压力等因素,利用真空热压烧结炉将两种不同尺寸的Cu-20Co-20Cr-20Ni粉末热压成块体合金,并利用电化学测试技术研究了它们在0.5mol·L^(-1)中性Na Cl溶液中的腐蚀行为以及纳米化对其腐蚀行为的影响。结果表明:当Cu-20Co-20Cr-20Ni合金处于0.5mol·L^(-1) Na Cl腐蚀溶液中时,纳米尺寸Cu-20Co-20Cr-20Ni合金较相应的常规尺寸合金自腐蚀电位发生正移,电荷传递电阻变大,腐蚀电流密度减小。可见,晶粒细化导致Cu-20Co-20Cr-20Ni合金的耐腐蚀性能增强。展开更多
基金financial supports provided by the National Natural Science Foundation of China (21406255)the Shanghai Science and Technology Committee (16dz1207200)the Youth Innovation Promotion Association CAS (2015231)
文摘The directly selective hydrogenolysis of xylitol to ethylene glycol(EG) and 1,2-propylene glycol(1,2-PDO)was performed on Cu–Ni–ZrO_2 catalysts prepared by a co-precipitation method. Upon optimizing the reaction conditions(518 K, 4.0 MPaH_2 and 3 h), 97.0% conversion of xylitol and 63.1% yield of glycols were obtained in water without extra inorganic base. The catalyst still remained stable activity after six cycles and above 80% total selectivity of glycols was obtained when using 20.0% xylitol concentration. XRD, TEM and ICP results indicated that Cu–Ni–ZrO_2 catalysts possess favorable stability. Cu and Ni are beneficial to the cleavage of C–O and C–H bond, respectively. To reduce the hydrogen consumption, isopropanol was added as in-situ hydrogen source and 96.4% conversion of xylitol with 43.6% yield of glycols were realized.
基金supported by the National Natural Science Foundation of China(Grant No.51301102)the Science and Technology Commission of Shanghai Municipality,China(Grant No.15ZR1416000)
文摘In the present work, the effects of Ni atoms and vacancy concentrations （0.1%, 0.5%, 1.0%） on the formation process of Cu solute clusters are investigated for Fe-1.24%Cu-0.62%Ni alloys by molecular dynamics （MD） simulations. The presence of Ni is beneficial to the nucleation of Cu precipitates and has little effect on coarsening rate in the later stage of aging. This result is caused by reducing the diffusion coefficient of Cu clusters and the dynamic migration of Ni atoms. Additionally, there are little effects of Ni on Cu precipitates as the vacancy concentration reaches up to 1.0%, thereby explaining the embrittlement for reactor pressure vessel （RPV） steel. As a result, the findings can hopefully provide the important information about the essential mechanism of Cu cluster formation and a better understanding of ageing phenomenon of RPV steel. Furthermore, these original results are analyzed with a simple model of Cu diffusion, which suggests that the same behavior could be observed in Cu-containing alloys.
文摘纳米材料因其自身独特性能而备受关注,从而引发了人们对其进行一系列的研究。采用机械合金化法(MA)和粉末冶金法(PM)制备了纳米尺寸和常规尺寸粉末,通过控制温度和压力等因素,利用真空热压烧结炉将两种不同尺寸的Cu-20Co-20Cr-20Ni粉末热压成块体合金,并利用电化学测试技术研究了它们在0.5mol·L^(-1)中性Na Cl溶液中的腐蚀行为以及纳米化对其腐蚀行为的影响。结果表明:当Cu-20Co-20Cr-20Ni合金处于0.5mol·L^(-1) Na Cl腐蚀溶液中时,纳米尺寸Cu-20Co-20Cr-20Ni合金较相应的常规尺寸合金自腐蚀电位发生正移,电荷传递电阻变大,腐蚀电流密度减小。可见,晶粒细化导致Cu-20Co-20Cr-20Ni合金的耐腐蚀性能增强。
