~1H MAS NMR characterization of hydrogen over silica-supported rhodium catalyst

Hydrogen species in both SiO2 and Rh/SiO2 catalysts pretreated in different atmospheres (H2, O2, helium or air) at different temperatures (773 or 973 K) were investigated by means of 1H MAS NMR. In SiO2 and O2-pretreated catalysts, a series of downfield signals at -7.0, 3.8-4.0, 2.0 and 1.5-1.0 were detected. The first two signals can be attributed to strongly adsorbed and physisorbed water and the others to terminal silanol (SiOH) and SiOH under the screening of oxygen vacancies in SiO2 lattice, respectively. Besides the above signals, both upfield signal at -110 and downfield signals at 3.0 and 0.0 were also detected in H2-pretreated catalyst, respectively. The upfield signal at -110 originated from the dissociative adsorption of H2 over rhodium and was found to consist of both the contributions of reversible and irreversible hydrogen. There also probably existed another dissociatively adsorbed hydrogen over rhodium, which was known to be p hydrogen and in a unique form of "delocalized hydrogen". It wa     

碱金属盐对ZSM-5分子筛晶化的影响

Effect of different alkali metal salts on the crystal size and the crystallization rate of ZSM-5 zeolite was de-tailedly investigated in this paper. The samples prepared by adding the different alkali metal salts were character-ized by using XRD， TEM， TG-DSC， BET and IR techniques. The XRD results showed that， for the nanosized ZSM-5 zeolite， the characteristic peaks broadened on the XRD patterns in comparison with the microsized ZSM-5 zeolite. The SEM results verified that the crystal size of zeolites prepared by adding different alkali metal salts had different results， and adding NaCl， NaC₂H₃O₂ and KCl showed the better effect of reducing crystal size， which are about of 40～60nm size. The crystallization curve of adding the different alkali metal salts suggested that the crystallization rate was significantly affected by the anions in the alkali metal salt besides the cations. Moreover， the crystal size likewise depended on the anion in the alkali metal salt. In addition， the BET results suggested that the nanosized ZSM-5 zeolite possessed a larger outer surface area in comparison with the microsized ZSM-5 zeolite. The thermostability of the samples was determined by TG-DSC technique， indicating that the nanosized ZSM-5 zeolite had a poor thermostability as compared with the microsized ZSM-5 zeolite. The possible difference of the samples with different crystal sizes on IR spectra was also given.     

Rh/SiO2催化剂上甲烷部分氧化制合成气的核磁共振研究

 利用1H MAS NMR技术,在甲烷部分氧化(POM)制合成气反应条件下研究了Rh/SiO2催化剂上氢与金属的相互作用及反应机理. 结果发现,氢气在Rh/SiO2上解离吸附后可能有四种存在形式: 化学位移为δ=-100～-120的可逆(αM)和不可逆(αI)吸附氢物种,δ=0～-100的“氢云”或“氢雾”形式的氢物种和δ=3.0的溢流氢物种. 溢流氢物种是由可逆吸附的氢物种和“氢云”或“氢雾”状态的氢物种溢流到SiO2上并弱吸附在桥式氧(Si-O-Si)附近而形成的. 溢流氢物种活化晶格氧,形成一种POM反应的活性氧物种OH-. 活性氧物种OH-反溢流到Rh上,并与CH4解离吸附在Rh上的CHx物种反应生成含氧中间物种CHxO. CHxO物种的化学位移为5～7. O2参与CHxO物种的进一步氧化,或补充溢流氢夺取桥式氧后形成的缺陷位上的晶格氧,在高温(973 K)反应条件下,O2可能优先补充缺陷位上的晶格氧,使CHx的氧化按表面反应机理进行.     

超微NaY分子筛的合成（II）—添加铝络合剂的影响

NaY分子筛合成体系中添加铝的络合剂（乙二胺四乙酸、柠檬本矣醋酸）,可有效地减小分子筛的晶粒尺寸及增加分子筛的晶化速度和SiO2/Al2O3物质的量比,在添加柠檬酸的合成体系中,考察了柠檬酸的添加量对NaY分子的筛晶化的影响,发现存在着一个最佳的柠檬酸的添加量范围,即n（柠檬酸）：n（氧化铝）≤2：1,在此范围内,NaY的晶化速率和硅铝比较高,而晶粒尺寸较小。     

Rh/SiO_2催化剂上甲烷部分氧化制合成气反应机理的研究(英文)

运用ＴＰＳＲ、ＴＲ－ＦＴＩＲ和化学捕获技术（ＣＨ３Ｉ作捕获剂）,探讨了Ｒｈ／ＳｉＯ２催化剂上的ＰＯＭ反应机理,由此提出热分解氧化机理,认为ＣＨｘ（ｘ＝１～３）和ＣＨｘＯ（ｘ＝１～３）可能是反应物种。     

添加成膜促进剂合成致密ZSM-5分子筛膜

报道了一种添加氯化钠低温条件下合成出具有纳米尺寸的ZSM-5分子筛，并以 其为晶种预吸附在多孔氧化铝载体上，再通过添加成膜促进剂氯化钠二次水热合成 制备出高度致密ZSM-5分子筛膜的新方法。通过考察添加的钠离子浓度对成膜的影 响，认为在一定浓度范围内钠离子能够促进成膜。SEM结果也验证了这一结论，分 子筛膜主要是由孪生聚晶分子筛组成。渗透结果显示，当添加量为x = 100 (Al_2O_3:84SiO_2:10Na_2O:15TPABr:3500H_2O)时，在室温和0.1 MPa的条件下， H_2/C_3的理想选择性最大值23.7，温度提高到200 ℃时的选择性下降为9.4，但仍 然高于努森扩散值（4.69），表面该膜具有高度的完整性。     

Rh/SiO_2催化剂上氢物种的~1H MAS NMR研究

采用1H MAS NMR技术, 分别对不同温度(773和973 K)、不同气氛(氢气、氧气、氦气及空气)条件下处理的SiO2和Rh/SiO2催化剂上的氢物种和含氢物种进行了研究. 在SiO2及经氧气处理的催化剂上, 检测到了位于约7.0, 3.8~4.0, 2.0及1.0~ 1.5处的一系列信号, 它们可分别归属为强吸附H2O, 物理吸附H2O, SiOH及受SiO2晶格氧缺陷位屏蔽影响的SiOH. 而在经氢气处理的催化剂上, 除了上述诸信号外, 还检测到了位于3.0和0.0处的低场信号及约位于?110处的高场信号. 其中, 低场信号分别归属为弱吸附在载体SiO2中的桥式晶格氧处的氢物种(溢流氢物种)和晶格氧缺陷处的氢物种(Si-H物种), 而高场信号则同时归属为解离吸附在Rh上的可逆吸附氢物种和不可逆吸附氢物种. 经氢气处理的催化剂上, 可能还形成了另外一种以独特的"离域氢"形式存在于Rh上的解离吸附氢物种(? 氢物种). 该氢物种应具有?20 ~ ?50的化学位移, 但其信号因被低场信号的自旋边带掩盖而未能在1H MAS NMR实验中直接观察到. 溢流氢物种和Si-H物种由可逆吸附氢物种和/或? 氢物种从Rh上向邻近的载体SiO2迁移而形成. 高温对于氢溢流过程更为有利.     

微波场中A型分子筛及分子筛膜合成的研究

Effects of aging time and alkalinity as well as cation concentration(Na⁺) on the synthesis of A type zeolite and zeolite membrane were investigated in this paper. The results showed that aging time for synthesis of A type zeolite and zeolite membrane had remarkable influence and alkalinity could accelerate the formation of zeolite but was disadvantage to zeolite membrane synthesis. Cation concentration(Na⁺) also couldn′t accelerate the synthesis of zeolite and zeolite membrane but it was probable an important factor to accelerate crystal growth .Moreover, more compact zeolite membranes could be synthesized by this method while the thickness of membrane was thinner than that of convention. Zeolites and zeolite membranes were characterized by XRD, TEM as well as IR characterization techniques.     

超微NaY分子筛的合成(Ⅰ)──添加轻稀土离子的影响

导向剂的陈化时间和反应胶的晶化温度可以影响NaY分子筛的晶化行为.随导向剂陈化时间的增加,NaY分子筛的晶化速度加快,晶粒尺寸减小;随晶化温度的升高,NaY分子筛的晶化速度加快,但晶粒尺寸增加.而向合成体系中添加轻稀土离子(Ln³⁺)对NaY分子筛的晶化行为影响更为明显.与未添加稀土离子时相比较,在一定的稀土离子添加量范围内[n(Ln³⁺)/n(Al³⁺)<0.2],NaY分子筛的晶化速度明显加快而晶粒尺寸显著减小,同时所合成出的NaY分子筛的n(SiO₂)/n(Al₂O₃)比也有较大的提高.添加稀土离子使合成体系中形成异晶晶种的Ln(OH)₃微晶,从而进一步引发NaY分子筛的成核.     

3-甲基吡啶的微波液相法合成

在液相条件下，采用微波协助合成3-甲基吡啶（1），其结构经GC-MS确证。研究了碳源(甘油、丙烯醛二甲缩醛和丙烯醛二乙缩醛)、氨源(硫酸亚铁铵、乙酸铵和氨水)、固体催化剂用量和溶剂(水、离子液体、二乙二醇甲醚、乙二醇丁醚和二甲基亚砜)对1合成反应的影响。结果表明：丙烯醛是重要的中间产物；在多相催化体系下，1收率最高可达到19.8%。