我国传染病微生态的预防发展趋势

我国传染病微生态的预防发展趋势范明远，向近敏，苏文金，郝维善，何明清，王世荣传染病的预防战略，传统观念仍局限于疫苗和药物两大主题。从微生态学（细胞或分子生态学）角度来考虑传染病的预防战略，是当今国际上生物医学的发展趋势。微生态学是边缘学科之一，根据其..

Catalytic Performance of MoVBiTeO/SiO_2 for Selective Oxidation of Propane to Acrolein

[中文文摘]用浸渍法制备了一系列不同Mo/V比的MoVBiTeO/SiO2催化剂,并用X射线衍射、拉曼光谱、X射线光电子能谱、程序升温还原和红外光谱等方法对催化剂的结构、氧化还原性质和酸性进行了表征,考察了催化剂对丙烷选择氧化制丙烯醛反应的催化性能.结果表明,Mo与V组分之间存在较强的相互作用,调变了催化剂的结构,并形成了氧化还原循环(V5++Mo5+V4++Mo6+),促进了催化剂中电子和O物种的传递,使催化剂的低温可还原性增强,催化活性提高.Mo组分有利于形成L酸位,而V组分有利于形成B酸位.这可能是丙烯醛选择性随Mo/V比增大而逐渐提高的原因之一.当Mo/V摩尔比为6时,催化剂具有最高的丙烯醛收率(9.7%)。[英文文摘]A series of MoVBiTeO/SiO2 catalyst samples with different Mo/V ratios were prepared by the impregnation method.The catalyst structure,reducibility,and acidity were characterized by XRD,Raman,XPS,TPR,and FT-IR techniques,and the catalytic performance of the catalyst for selective oxidation of propane to acrolein was evaluated.The results indicated that the interaction between Mo and V components modified the catalyst structure,and the redox cycle of V5++Mo5+V4++Mo6+ was formed.The improvement in the reducibility of the catalyst might be responsible for the increase in propane conversion. The V and Mo components were responsible for B acid and L acid , respectively. When the Mo/ V ratio increased , the amount of B acid de2 creased , and the catalyst selectivity for acrolein increased. Among the investigated catalyst samples , the sample with a Mo/ V molar ratio of 6 exhibited the best catalytic performance.国家重点基础研究发展计划(2005CB221408); 国家自然科学基金(20433030,20021002,20423002); 福建省科技重大专项(2005HZ01-3)

MoPO/SiO_2催化剂上丙烷选择氧化制丙烯醛

研究了MoPO/SiO2 催化剂对丙烷选择氧化制丙烯醛的催化性能 .MoO/SiO2 催化剂主要表现出对丙烷氧化脱氢的催化性能 ,在该催化剂中添加磷后 ,丙烷转化率和选择氧化产物丙烯醛的选择性明显提高 .催化剂的X射线衍射、拉曼光谱、程序升温还原、吡啶吸附红外光谱和程序升温脱附等表征结果表明 ,MoO/SiO2 催化剂主要含有MoO3 晶相 ,添加磷后 ,形成了表面多钼酸物种 ,磷以PO4四面体结构存在于表面 ,可能形成部分Mo—O—P键 ,从而抑制了MoO3 在MoPO/SiO2 上的形成 ,起到分隔活性中心的作用 .在MoO/SiO2 催化剂中添加磷后 ,催化剂的B酸和L酸酸性均增强 ,有利于丙烷在MoPO/SiO2 催化剂表面活性的提高 .由此可见 ,催化剂表面结构和酸性的变化可能是导致MoPO/SiO2 催化性能提高的原

MoBiTeO/SiO_2催化剂在丙烷选择氧化反应中的表面结构重组

考察了MoBiTeO/SiO2催化剂对丙烷选择氧化制丙烯醛的催化性能,并采用原位拉曼、X射线衍射和X光电子能谱等技术研究了催化剂在反应过程中的结构重组及其对催化性能的影响.实验结果表明,反应前,MoBiTeO/SiO2催化剂主要由Te多钼酸盐物种组成;在570℃和C3H8/O2/N2=1.2/1/4的反应条件下,MoBiTeO/SiO2催化剂中的部分Te组分被深度还原为金属Te而流失,使部分Te多钼酸盐物种进行了结构重组形成了MoO3物种.Te多钼酸盐和MoO3之间的协同作用使催化剂的催化性能提高

丙烷选择氧化制丙烯醛MoBiTeO/SiO_2催化剂中Te组分的作用

用浸渍法制备了一系列不同Te含量的MoBiTeO/SiO2催化剂,并用XRD、Raman、XPS、NH3-TPD、吡啶吸附FT-IR和催化剂性能评价等方法考察了Te组分对催化剂的结构、酸性及其丙烷选择氧化制丙烯醛性能的影响.结果表明,催化剂中Mo氧化物与Te氧化物之间发生了相互作用,通过形成Mo—O—Te桥氧键生成了Te多钼酸盐物种,在一定程度上分散了Mo-O活性中心,同时TeOx具有脱除丙烯α-H、插氧并将其转化为丙烯醛的功能,因此,在MoBiO/SiO2催化剂中添加Te组分使丙烯醛选择性有显著的提高.但是Te的加入同时也使催化剂中B酸增强,这不利于丙烯醛生成.因此,Te添加量有一最佳范围,nTe/nMo为0.05-0.1时催化剂具有较好的催化性能

Mo-V-Co-O催化剂的丙烷氧化脱氢性能研究

考察Mo2V1M0.5Ox(M=Co,Zr,Nb,Bi,Ni,Fe,Mn,Al,Sb,P,Nd,Te)系列催化剂的丙烷氧化脱氢性能,其中,添加Co的催化剂表现出较好的催化活性和丙烯选择性.对催化剂的BET,XRD,H2 TPR和NH3 TPD表征结果表明,Co元素的添加,改变了催化剂的物相组成,氧化还原性和酸碱性质,从而提高了Mo2V1Co0.5Ox 催化剂的丙烷氧化脱氢性能

Te掺杂对MoPO/SiO_2催化剂上丙烷选择氧化制丙烯醛反应的影响

考察了Te的添加及Te含量对MoPO/SiO2催化剂催化丙烷选择氧化制丙烯醛反应性能的影响.MoPO/SiO2催化剂对丙烷选择氧化制丙烯醛反应的中间产物丙烯选择性较高,而Te的添加促进了丙烯向丙烯醛的转化.N2吸附、XRD、Raman、XPS、H2-TPR、丙烷脉冲、NH3-TPD和Py-IR等实验结果表明,催化剂添加Te后虽然比表面积有所下降,但单位比表面积上的酸量增加,催化剂低温可还原性得到改善,从而有利于丙烷的转化.Te可能有利于丙烯α-H的脱除和/或烯丙基的插氧反应

浆态法制备的MoVTeNbO催化剂上的乙烷氧化脱氢(英文)

采用浆态法在N2 气氛下焙烧制得了MoV0 .3 Te0 .2 3 Nb0 .1Ox 催化剂.在以该催化剂催化的乙烷氧化脱氢制乙烯的反应中,4 4 0℃下乙烷的转化率和乙烯的选择性均在90 %左右,乙烯产率达80 9% .但在空气气氛下焙烧得到的催化剂几乎没有催化活性.用XRD和SEM等方法考察了催化剂的结构

Catalytic performance of MoVBiTeO/SiO2 for selective oxidation of propane to acrolein

A series of MoVBITeO/SiO2 catalyst samples with different Mo/V ratios were prepared by the impregnation method. The catalyst structure, reducibility, and acidity were characterized by XRD, Raman, XPS, TPR, and FT-IR techniques, and the catalytic performance of the catalyst for selective oxidation of propane to acrolein was evaluated. The results indicated that the interaction between Mo and V components modified the catalyst structure, and the redox cycle of V5+ + Mo5+ V4+ + Mo6+ was formed. The improvement in the reducibility of the catalyst might be responsible for the increase in propane conversion. The V and Mo components were responsible for B acid and L acid, respectively. When the Mo/V ratio increased, the amount of B acid decreased, and the catalyst selectivity for acrolein increased. Among the investigated catalyst samples, the sample with a Mo/V molar ratio of 6 exhibited the best catalytic performance

Selective oxidation of propane to acrolein over MoPO/SiO2 catalyst

The selective oxidation of propane to acrolein over the MoPO/SiO2 catalyst has been studied. MoO/SiO2 exhibits only activity for the oxidative dehydrogenation of propane to propene. The propane conversion and acrolein selectivity are evidently increased by the addition of P to MoO/SiO2. The catalysts were characterized by XRD, Raman spectroscopy, H-2-TPR, NH3-TPD and FT-IR spectroscopy. The XRD and Raman results show that crystalline MoO3 is dominant on the silica-supported molybdenum oxide catalyst, while polymolybdate species are present on P-doped catalysts. Compared to the P-O-P stretching vibration at 905 cm(-1) in PO/SiO2, the P-doped sample exhibits the Raman band of the asymmetric PO4 stretching mode at 1085 cm(-1). Therefore, Mo-O-P bonds are likely to be formed on the P-doped catalyst, and the active sites are isolated by the phosphorus in MOPO/SiO2, preventing the growth of crystallized MoO3. These changes in structure and thus the improvement in reducibility of the MoPO/SiO2 catalyst may be responsible for the increase in propane conversion and acrolein selectivity. Furthermore, the results of FT-IR spectroscopy of pyridine adsorption and NH3-TPD show that both Bronsted and Lewis acid sites on the surface of the P-doped sample are stronger than those on MoO/SiO2. These suggest that the addition of phosphorus modifies the surface structure and enhances the surface acidity of the supported catalyst, thus improving the behavior of the catalyst