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碱催化剂g-C3N4在液相反应中溶胀特性的研究 被引量:2
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作者 吴结群 华伟明 +1 位作者 乐英红 高滋 《物理化学学报》 SCIE CAS CSCD 北大核心 2020年第1期227-233,共7页
通过三聚氰胺、双腈胺、硫脲或尿素的高温热解制备了四种比表面不同的石墨型碳化氮材料(g-C3N4),利用X射线衍射(XRD)、扫描电子显微镜(SEM)、傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)、热重分析(TGA)和N2吸附方法对所得材料进... 通过三聚氰胺、双腈胺、硫脲或尿素的高温热解制备了四种比表面不同的石墨型碳化氮材料(g-C3N4),利用X射线衍射(XRD)、扫描电子显微镜(SEM)、傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)、热重分析(TGA)和N2吸附方法对所得材料进行结构与表面性质的表征,用CO2程序升温脱附(CO2-TPD)和酸碱滴定方法测试了其碱性。考察了这些材料对于不同溶剂中苯甲醛与丙二腈Knoevenagel缩合反应的催化活性。g-C3N4在弱极性溶剂甲苯中的催化活性很低,且活性大小与其比表面和表面碱性密切相关,而在极性溶剂乙醇中四种g-C3N4的催化活性则相差不大,且都远高于甲苯中的活性。上述结果无法用常规的碱性表征数据来解释。进一步的实验证明在极性溶剂中g-C3N4会发生溶胀,使得表面暴露更多的碱性位,因而催化活性大大提高。不同溶剂中的反应结果表明g-C3N4的溶胀效应随反应溶剂的极性增加而增强。重复利用实验表明gC3N4在液相反应中具有良好的稳定性,其对于苯甲醛的转化率在重复利用三次后由74.2%下降至63.8%。 展开更多
关键词 g-C3N4 碱催化 KNOEVENAGEL缩合 溶胀效应
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Dehydrogenation of Isobutane to Isobutene with Carbon Dioxide over SBA-15-Supported Chromia-Ceria Catalysts 被引量:1
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作者 Chunling Wei Fangqi Xue +4 位作者 Changxi Miao Yinghong Yue Weimin Yang weiming hua Zi Gao 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2017年第10期1619-1626,共8页
A series of SBA-15-supported chromia-ceria catalysts with 3% Cr and 1%--5% Ce (3Cr-Ce/SBA) were pre- pared using an incipient wetness impregnation method. The catalysts were characterized by XRD, N2 adsorption, SEM,... A series of SBA-15-supported chromia-ceria catalysts with 3% Cr and 1%--5% Ce (3Cr-Ce/SBA) were pre- pared using an incipient wetness impregnation method. The catalysts were characterized by XRD, N2 adsorption, SEM, TEM-EDX, Raman spectroscopy, UV-vis spectroscopy, XPS and H2-TPR, and their catalytic performance for isobutane dehydrogenation with CO2 was tested. The addition of ceria to SBA-15-supported chromia improves the dispersion of chromium species. 3Cr-Ce/SBA catalysts are more active than SBA-15-supported chromia (3Cr/SBA), which is due to a higher concentration of Cr^6+ species present on the former catalysts. The 3Cr-3Ce/SBA catalyst shows the highest activity, which gives 35.4% isobutane conversion and 89.6% isobutene selectivity at 570℃ after 10 min of the reaction. 展开更多
关键词 isobutane dehydrogenation carbon dioxide chromia-ceria SBA-15 supported catalyst
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Isobutane Dehydrogenation Assisted by C02 over Silicalite-i-Supported ZnO Catalysts: Influence of Support Crystallite Size
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作者 Yajun Luo Chunling Wei +3 位作者 Changxi Miao Yinghong Yue weiming hua Zi Gao 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2020年第7期703-708,共6页
The ZnO catalysts supported on Silicalite-1 zeolites with different crystallite sizes(0.08,0.35,1 and 1.7 jjm,respectively)and 5%Zn were synthesized via an incipient wetness method.The catalysts were characterized by ... The ZnO catalysts supported on Silicalite-1 zeolites with different crystallite sizes(0.08,0.35,1 and 1.7 jjm,respectively)and 5%Zn were synthesized via an incipient wetness method.The catalysts were characterized by XRD,N2 adsorption,SEM,TEM-EDX,DRIFT spectra and NH3-TPD,and their catalytic performance in isobutane dehydrogenation assisted by C02 was investigated.The catalytic activity is strongly dependent on the crystallite size of Silicalite-1 support.The ZnO/S-l-O.35 catalyst with ca.0.35 μmcrystallite size displays the highest activity,affording an initial isobutane conversion of 51.0%and 74.5%isobutene selectivity.This can be attributed to a higher amount of acid sites present on this catalyst as well as the largest amount of nest silanols possessed by the S-l-0.35 support. 展开更多
关键词 method. CRYSTALLITE CATALYST
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