甲醇具有结构简单、含氢量高、产能大等优点,利用甲醇与水蒸气进行重整是一种节能高效的现场制氢方式。甲醇水蒸气重整(MSR)与燃料电池联用能够实现多场景应用,但由于反应温度较高(250~300℃),存在启动速度较慢、副产CO含量较高和热效...甲醇具有结构简单、含氢量高、产能大等优点,利用甲醇与水蒸气进行重整是一种节能高效的现场制氢方式。甲醇水蒸气重整(MSR)与燃料电池联用能够实现多场景应用,但由于反应温度较高(250~300℃),存在启动速度较慢、副产CO含量较高和热效率较低等问题。低温甲醇水重整(LT-Methanol Water Reforming,LT-MWR)包括低温甲醇水蒸气重整(LT-MSR)与液相甲醇水重整(Aqueous-phase Reforming of Methanol,APRM),反应通常在200℃以下进行,同时保持较高的反应活性,进而能够减少预热时间、减弱副反应发生,且能与燃料电池实现更强的热耦合。本工作首先介绍了商用催化剂优异的性能与存在的缺陷,然后对低温甲醇水重整制氢催化剂,诸如Cu基催化剂、贵金属催化剂与光协同催化剂的研究进展进行了回顾。归纳了低温铜基催化剂的改性策略,包括合成方法、结构设计与元素掺杂。对国内外商用CuZnAlO_(x)催化剂结构与性能的测试表明,其转化率高和稳定性好,存在的缺陷是价格较贵且在低温区催化活性急剧下降。Cu基催化剂活性受温度影响较大,在低温区活性很低,但通过适当的改性能够实现其应用价值,其改性策略包括合成方法、结构设计与元素掺杂。贵金属催化剂低温下活性较高,但存在价格昂贵、合成复杂等缺点。光协同催化剂则是在光照条件下进行催化重整,尚处于研究阶段。对于Cu基催化剂,合成方法的改进能够大大改善催化剂的微观混合程度与可重现性。适当的结构设计可提升催化剂的比表面积与热稳定性。元素掺杂则能够提升活性组分的分散度,修饰催化剂表面结构。三种改性策略能够有效提升Cu基催化剂低温下甲醇重整制氢的性能,在保持较高活性的同时,降低CO副产物的含量。展望了低温甲醇水重整制氢催化剂的发展前景和挑战,对催化剂的开发与应用有指导意义。要点:(1)展开更多
Bulk coal combustion in rural households is a major contributor to PM_(2.5)pollution in Northern China[1,2].To promote the energy transition and reduce bulk coal combustion for heating in rural areas,China initiated t...Bulk coal combustion in rural households is a major contributor to PM_(2.5)pollution in Northern China[1,2].To promote the energy transition and reduce bulk coal combustion for heating in rural areas,China initiated the Winter Clean Heating Action Plan in Rural Northern China in 2017,hereinafter referred to as rural clean heating(RCH)[3].The 2+26 region,comprising Beijing,Tianjin,and 26 other municipalities in the surrounding area(Fig.S1 online),is the key implementation area for the RCH.展开更多
Radix Astragali has been an important traditional Chinese herbal medicine for over 2000 years. It is derived from two plant species, namely, Astragalus mongholicus [Astragalus membranaceus (Fisch.) Bge. var. mongholic...Radix Astragali has been an important traditional Chinese herbal medicine for over 2000 years. It is derived from two plant species, namely, Astragalus mongholicus [Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao] and Astragalus membranaceus [Astragalus membranaceus (Fisch.) Bge.] (Leguminosae ), according to the Pharmacopoeia of the People’s Republic of China. In this study, the genetic diversity and genetic relationships of Radix Astragali in China were analyzed by Inter-Simple Sequence Repeat (ISSR) markers. A total of 25 highly polymorphic ISSR primers were selected to amplify 95 Radix Astragali samples. Among 273 DNA bands amplified, 213 are polymorphic (percentage of polymorphic bands: 78%). The average value of the amplified bands was 10.9 for each primer, and the number varied from 4 to 20. The genetic diversity of the 95 Radix Astragali samples was analyzed by using POPGENE 1.32 software. The Nei’s genetic diversity index (h) and Shannon’s information index (I ) were 0.3590 and 0.5308, respectively, which indicated the abundant genetic diversity of Radix Astragali . The level of genetic diversity in A. membranaceus (h: 0.3109, I : 0.4657) was slightly lower than that in A. mongholicus (h: 0.3364, I : 0.4969). Considering the average genetic similarity coefficient by NTSYS analysis to cluster the A. membranaceus of nine habitats and A. mongholicus of five habitats, Radix Astragali samples were clustered into two groups according to place of origin. This clustering is different from traditional clustering, which divides groups according to species. Results obtained from this study will provide a theoretical basis for the molecular study on germplasm resources of Radix Astragali .展开更多
STSE(Science,Technology,Society and Environment)教育理念注重在情境化教学中促进学生对知识的理解和掌握,强调科学、技术、社会、环境的相互关系,并实现学生对社会发展和进步的进一步认识。本文以“北京冬奥会”这一热点事件为情境...STSE(Science,Technology,Society and Environment)教育理念注重在情境化教学中促进学生对知识的理解和掌握,强调科学、技术、社会、环境的相互关系,并实现学生对社会发展和进步的进一步认识。本文以“北京冬奥会”这一热点事件为情境,基于STSE教育理念,通过将化学与北京冬奥会中社会、技术、环境等元素有机融合,阐述化学如何为北京冬奥会赋能,引导学生对化学产生兴趣,并在潜移默化中提升学生可持续发展的意识,为现代化科技强国建设培养化学类人才。展开更多
分析了旋流离心连续分选机的作用原理并用其对攀枝花钛磁铁矿进行分级实验.结果表明,旋流离心连续分选机的给矿浓度、给矿压力、反冲水压力、溢流口压力和沉砂口压力等操作条件对沉砂的粒度分布均有明显影响,在给矿浓度5%、给矿压力70-7...分析了旋流离心连续分选机的作用原理并用其对攀枝花钛磁铁矿进行分级实验.结果表明,旋流离心连续分选机的给矿浓度、给矿压力、反冲水压力、溢流口压力和沉砂口压力等操作条件对沉砂的粒度分布均有明显影响,在给矿浓度5%、给矿压力70-72 k Pa、反冲水压力5 k Pa、溢流口压力40-50 k Pa、沉砂口压力45-55 k Pa的操作条件下,钛磁铁矿分级后0.15-2.00和0.074-0.15 mm粒级的颗粒分别占80%-83%和60%-65%,小于0.074 mm的颗粒仅占22%-28%.展开更多
文摘甲醇具有结构简单、含氢量高、产能大等优点,利用甲醇与水蒸气进行重整是一种节能高效的现场制氢方式。甲醇水蒸气重整(MSR)与燃料电池联用能够实现多场景应用,但由于反应温度较高(250~300℃),存在启动速度较慢、副产CO含量较高和热效率较低等问题。低温甲醇水重整(LT-Methanol Water Reforming,LT-MWR)包括低温甲醇水蒸气重整(LT-MSR)与液相甲醇水重整(Aqueous-phase Reforming of Methanol,APRM),反应通常在200℃以下进行,同时保持较高的反应活性,进而能够减少预热时间、减弱副反应发生,且能与燃料电池实现更强的热耦合。本工作首先介绍了商用催化剂优异的性能与存在的缺陷,然后对低温甲醇水重整制氢催化剂,诸如Cu基催化剂、贵金属催化剂与光协同催化剂的研究进展进行了回顾。归纳了低温铜基催化剂的改性策略,包括合成方法、结构设计与元素掺杂。对国内外商用CuZnAlO_(x)催化剂结构与性能的测试表明,其转化率高和稳定性好,存在的缺陷是价格较贵且在低温区催化活性急剧下降。Cu基催化剂活性受温度影响较大,在低温区活性很低,但通过适当的改性能够实现其应用价值,其改性策略包括合成方法、结构设计与元素掺杂。贵金属催化剂低温下活性较高,但存在价格昂贵、合成复杂等缺点。光协同催化剂则是在光照条件下进行催化重整,尚处于研究阶段。对于Cu基催化剂,合成方法的改进能够大大改善催化剂的微观混合程度与可重现性。适当的结构设计可提升催化剂的比表面积与热稳定性。元素掺杂则能够提升活性组分的分散度,修饰催化剂表面结构。三种改性策略能够有效提升Cu基催化剂低温下甲醇重整制氢的性能,在保持较高活性的同时,降低CO副产物的含量。展望了低温甲醇水重整制氢催化剂的发展前景和挑战,对催化剂的开发与应用有指导意义。要点:(1)
基金supported by the National Natural Science Foundation of China(72074155,72074137,72374107)the Shandong Province Natural Science Foundation(ZR2021YQ27)+2 种基金the Natural Science Foundation of Jiangsu Province(BK20230062)the National Key R&D Program of China(2022YFF0802504)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX22_1223)。
文摘Bulk coal combustion in rural households is a major contributor to PM_(2.5)pollution in Northern China[1,2].To promote the energy transition and reduce bulk coal combustion for heating in rural areas,China initiated the Winter Clean Heating Action Plan in Rural Northern China in 2017,hereinafter referred to as rural clean heating(RCH)[3].The 2+26 region,comprising Beijing,Tianjin,and 26 other municipalities in the surrounding area(Fig.S1 online),is the key implementation area for the RCH.
文摘Radix Astragali has been an important traditional Chinese herbal medicine for over 2000 years. It is derived from two plant species, namely, Astragalus mongholicus [Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao] and Astragalus membranaceus [Astragalus membranaceus (Fisch.) Bge.] (Leguminosae ), according to the Pharmacopoeia of the People’s Republic of China. In this study, the genetic diversity and genetic relationships of Radix Astragali in China were analyzed by Inter-Simple Sequence Repeat (ISSR) markers. A total of 25 highly polymorphic ISSR primers were selected to amplify 95 Radix Astragali samples. Among 273 DNA bands amplified, 213 are polymorphic (percentage of polymorphic bands: 78%). The average value of the amplified bands was 10.9 for each primer, and the number varied from 4 to 20. The genetic diversity of the 95 Radix Astragali samples was analyzed by using POPGENE 1.32 software. The Nei’s genetic diversity index (h) and Shannon’s information index (I ) were 0.3590 and 0.5308, respectively, which indicated the abundant genetic diversity of Radix Astragali . The level of genetic diversity in A. membranaceus (h: 0.3109, I : 0.4657) was slightly lower than that in A. mongholicus (h: 0.3364, I : 0.4969). Considering the average genetic similarity coefficient by NTSYS analysis to cluster the A. membranaceus of nine habitats and A. mongholicus of five habitats, Radix Astragali samples were clustered into two groups according to place of origin. This clustering is different from traditional clustering, which divides groups according to species. Results obtained from this study will provide a theoretical basis for the molecular study on germplasm resources of Radix Astragali .
文摘STSE(Science,Technology,Society and Environment)教育理念注重在情境化教学中促进学生对知识的理解和掌握,强调科学、技术、社会、环境的相互关系,并实现学生对社会发展和进步的进一步认识。本文以“北京冬奥会”这一热点事件为情境,基于STSE教育理念,通过将化学与北京冬奥会中社会、技术、环境等元素有机融合,阐述化学如何为北京冬奥会赋能,引导学生对化学产生兴趣,并在潜移默化中提升学生可持续发展的意识,为现代化科技强国建设培养化学类人才。
文摘分析了旋流离心连续分选机的作用原理并用其对攀枝花钛磁铁矿进行分级实验.结果表明,旋流离心连续分选机的给矿浓度、给矿压力、反冲水压力、溢流口压力和沉砂口压力等操作条件对沉砂的粒度分布均有明显影响,在给矿浓度5%、给矿压力70-72 k Pa、反冲水压力5 k Pa、溢流口压力40-50 k Pa、沉砂口压力45-55 k Pa的操作条件下,钛磁铁矿分级后0.15-2.00和0.074-0.15 mm粒级的颗粒分别占80%-83%和60%-65%,小于0.074 mm的颗粒仅占22%-28%.
