Zn/H-ZSM-5催化剂上的二甲醚芳构化反应

 考察了 H-ZSM-5 和 Zn/H-ZSM-5 催化剂的二甲醚芳构化性能. 结果表明, H-ZSM-5 分子筛催化剂酸性的增强和酸中心的增多有利于二甲醚芳构化. 当在 H-ZSM-5 催化剂中加入 2% Zn 时, 在 360 oC 下反应时总芳烃收率从 50.0% 增加至 66.2%, C8 芳烃收率从 28.6% 增加到 39.0%. 反应温度升高到 480 oC 时, 总芳烃收率增加至 78.0%.     

Aromatization with dearylation on Hantzsch cyclocondensation of 4-(dimethylamino)benzaldehyde,cyclohexane-1,3-diones,and some 1,3-[N,C]dinucleophiles

The Hantzsch three-component cyclization of 4-(dimethylamino)benzaldehyde, cyclohexane-1,3-diones, and some 1,3-[N,C]-dinucleophiles (5-amino-3-methyl-1-phenylpyrazole, 3,5-dimethoxyaniline, and 4-amino-1,3-dimethylpyrimidine-2,6-dione) proceeds in boiling acetic acid with the splitting off N,N-dimethylaniline and the formation of polycondensed heterocyclic sytems with a γ-unsubstituted pyridine ring (pyrazolo[3,4-b]quinoline, acridine, and pyrimido[4,5-b]quinoline). Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 244-251, February, 2009.     

Methane aromatization in the absence of oxygen over extruded and molded MoO3/ZSM-5 catalysts: Influences of binder and molding method

The influences of binder and molding method on the catalytic performance of methane aromatization in the absence of O2 over MoO3/ZSM-5 catalysts were investigated. SEM, NH3-TPD, FT-IR of adsorbed pyridine, N2 adsorption-desorption, cyclohexane adsorption and XPS were employed to characterize the physical and chemical properties of the catalysts. It was found that SiO2 was a suitable binder for the catalyst due to its appropriate weak acidity. The laminar catalyst comprising of an inert spherical core and a MoO3/ZSM-5 laminar shell with 0.1-0.2 mm in thickness showed a better catalytic performance than the extruded catalyst. The improved activity of the laminar catalyst could be attributed to the easy carbonization of Mo species and the quick removal of reaction products from the catalyst surface.     

Propane Aromatization over Mo/HZSM-5 Catalysts

Impregnation, mechanical mixing and hydrothermal treatment methods were used to introduce molybdenum species into the HZSM-5 zeolite. The structure and surface acidity of the catalysts were studied by means of XRD, FT-IR, NH3-TPD, TPR and XPS. The effects of Mo content and reaction time on stream on the aromatization of propane were investigated. It was found that the performance of the Mo/HZSM-5 catalyst prepared by the hydrothermal treatment method was much better than that of the other two catalysts. For example, under the reaction conditions of 823 K and 600 h-1, propane conversion and aromatics selectivity over the catalyst prepared by hydrothermal pretreatment could reach 89.17% and 78.56%, respectively. XRD and XPS results showed that the Mo species in the catalysts prepared by hydrothermal treatment were highly dispersed on the surface of the HZSM-5, and larger amounts of them could penetrate into the HZSM-5 channel, as compared with the other two kinds of catalysts. These factors may be responsi     

甲烷在6%Zn/HZSM-5催化剂上的低温转化 Catalytic Conversion of Methane at Low Temperature over 6%Zn/HZSM-5 Zeolite

 采用丙烷和甲烷混合物作为共反应物进行无氧芳构化反应. 在600 ℃,3000 h-1和甲烷/丙烷摩尔比为0.6的条件下,甲烷可以在6%Zn/HZSM-5分子筛催化剂上被有效地活化,甲烷的转化率可达32.4%,丙烷的转化率为89.5%,反应的主要产物为芳烃,其选择性达到89.7%. 甲烷与丙烷的摩尔比对芳烃产物的选择性有影响. 在没有丙烷参与时该催化剂在600 ℃下对甲烷转化没有活性. 推测是丙烷脱氢或裂解过程的中间产物活化了甲烷. 低碳烷烃对甲烷的活化可能是实现甲烷低温转化的一条有效途径.     

CORRELATION OF ALKALINITY WITH AROMATIZATION SELECTIVITY OF C_6 PARAFFIN OVER Pt/ML(M=Li,Na,K AND Rb)CATALYSTS

The effect of alkaline metals such as I,i, Na, K and Rb on the aromatization of n-C6, paraffin over Pt/ML zeolite catalyst was studied. It was shown that the alkaline cations, especially the Rb with strong basicitv and larger radius, lead Pt particles to disperse well on the surface of L zeolite. A stronger basicity of the modifying cation resulted in higher activity and selectivity to aromatization of n-C6. It is argued that the alkali cations affected the electronic slate of P1. leading to Ptδ-. which caused a decrease of dehvdrogenation activity and an increase of the selectivity to aromatization.     

Pt／ZSM—5吸附与催化性能的研究

本文研究了氨和正已烷在Ｐｔ／ＺＳＭ－５上的吸附性能并考察了Ｐｔ含量和焙烧温度对正已烷芳构化性能的影响。结果表明，Ｐｔ含量和焙烧温度对吸附和催化性能有影响。Ｐｔ与分子筛的酸中心对芳构化均有作用。     

The <Emphasis Type="Italic">p</Emphasis>-(dimethylamino)benzaldehyde modification of Hantzsch reaction: Synthesis of 6-(1H-benzimidazol-2-yl)pyrido[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidino-2,4(1H, 3H)-diones

The reaction between p-(dimethylamino)benzaldehyde and 2-acylmethyl-1H-benzimidazoles and 6-amino-1,3-dimethylpyrimidino-2,4(1H,3H)-dione has given previously unknown 5-unsubstituted 6-(1H-benzimidazol-2-yl)pyrido[2,3-d]pyrimidino-2,4(1H,3H)-diones. The reaction occurs on boiling in acetic and acid and includes the formation of 1,4-dihydropyridine-bearing compounds in accordance with the Hantzsch reaction scheme and aromatization as a result of cleavage of N,N-dimethylaniline. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 585–589, April 2007.     

Direct aromatization of chlorohydroazulenones with triflic anhydride: access to chloroazulenyl triflates

A direct and efficient aromatization of chlorohydroazulenones has been achieved by using triflic anhydride and then lutidine or tropylium cation to afford selectively chloroazulenes and chloroazulenyl triflates, respectively.     

Co改性Mo/MCM-22催化剂上甲烷无氧芳构化及积炭研究

 研究了Co的添加对Mo／MCM－22催化剂甲烷无氧芳构化反应性能的影响．发现用共浸渍法制备的Co／Mo摩尔比为0．2的催化剂具有较高的活性,而先浸渍Mo后浸渍Co的催化剂具有较好的稳定性．XRD实验表明,Co及Mo的氧化物均高度分散在分子筛表面,其担载降低了分子筛的衍射强度．不同接触时间下催化剂的反应结果表明,接触时间长,积炭选择性随接触时间增加而迅速增加;接触时间短,积炭选择性随接触时间增加而减少．积炭催化剂的TG研究表明,催化剂上的积炭主要有两种形式．低温积炭随反应时间增加而迅速增多,高温积炭的变化则较为缓慢．低温积炭可能是导致催化剂活化和失活的主要原因．高温积炭可能是一种大分子量的碳氢物种,位于MCM－22分子筛的“超笼”中,表明MCM－22有较大的容积炭能力．