甲醇制丙烯:最重要的催化剂及其性能

由于世界范围内原油缺乏和丙烯需求量增长,在甲醇转化制烃类的不同路线中,甲醇制丙烯(MTP)过程得到发展.本文讨论了催化剂结构对MTP工艺条件的影响以及分子筛酸性、晶粒尺寸、中孔特性和拓扑结构等因素对催化剂催化MTP反应活性和选择性的影响.     

Sonochemical syntheses of xanthene derivatives using zeolite-supported transition metal catalysts in aqueous media

An efficient green method for the syntheses of biologically active xanthene derivatives by use of zeolite-supported transition metal catalysts is described. A Fe-Cu/ZSM-5 heterogeneous catalyst has the highest activity in the one-pot syntheses with a wide range of aldehydes and cyclic 1,3-diketones, under ultrasonic irradiation in water at ambient temperatures. The three-component condensation in the presence of supported metal catalysts is operationally simple, requires no expensive or toxic reagents, and gives high yields in short reaction times.     

Nanostructure Copper-exchanged ZSM-5 Catalytic Activity for Conversion of Volatile Organic Compounds (Toluene and Ethyl Acetate)

Gas phase catalytic oxidation of ethyl acetate and toluene was examined over copper modified ZSM‐5 catalysts under atmospheric pressure. Nanostructure of ZSM‐5 was characterized by XRD, SEM and TEM techniques. Elemental composition of ZSM‐5 was determined using EDX, ICP‐AES and XPS techniques. Results of catalytic studies showed better catalytic activity of Cu‐ZSM‐5 catalysts than those of parent ZSM‐5 and HZSM‐5, which revealed catalytic role of copper ions in the Cu‐ZSM‐5 catalysts. Effects of some parameters over catalytic conversion of these compounds were also studied. Ethyl acetate showed more reactivity than toluene over the Cu‐ZSM‐5 catalysts. Furthermore, the catalytic activity of Cu‐ZSM‐5 catalysts increased with increasing the copper loadings. The conversion behavior of a binary mixture of ethyl acetate and toluene was different from that of a single form. A promotive and inhibitive behavior was observed for conversion of ethyl acetate and toluene in the binary mixture, respectively. Water vapor as co‐feed had an inhibitive effect on conversion of organic compounds over the Cu‐ZSM‐5 catalysts.     

Durable and highly selective tungsten-substituted MFI metallosilicate catalysts for the methanol-to-propylene process by designing a novel feed-supply technique

For the catalytic reaction of methanol to propylene (MTP), conventional H-ZSM-5 and W-substituted MFI metallosilicate catalysts were successfully synthesized using a hydrothermal method. The catalysts were properly characterized by several techniques. For comparison of the catalytic lifetime, feedstock of MTP was provided by both a conventional system and a novel feed-supply technique. The novel technique used the piezoelectric ultrasonic effect. It was revealed that feed composition via novel feed-supply technique remained totally constant, whereas with conventional system it relatively changed. Complete methanol conversion, higher propylene yield of 54.3%, greater light olefin yield of 85.2%, and longer-term catalytic lifetime of 101 h were productively obtained for H-W(250)AlMFI catalyst using a novel method for provision of feed. The better performance of this catalyst can be attributed to adequate content of tungsten, appropriate mesoporosity, sufficient strength of acidic sites, and stable feed composition of the novel feed-supply technique. Furthermore, the MTP process was miniaturized by the piezoelectric ultrasonic device.     

Synthesis of silyl-protected terminal thioalkyne-substituted tetraaryl imidazoles: utilization of Ag–Fe/ZSM-5 bimetallic nanooxides for cyclocondensation of polysubstituted imidazoles

Research on Chemical Intermediates - An improved one-pot and ecofriendly approach to tri- and tetraaryl imidazoles through three- and four-component coupling reactions under neutral and...