Effect of the oxide support on the propane ammoxidation with Sb–V–O-based catalysts

The role of Nb₂O₅ and γ-Al₂O₃ oxide supports on the ammoxidation of propane on supported mixed Sb–V oxide at different Sb+V surface coverages is studied. Sb and V oxide species on alumina and on niobia support show different structural features that reflect in different performance during the ammoxidation of propane to acrylonitrile. Niobia-supported catalysts are much more selective to acrylonitrile than alumina-supported ones. Alumina interacts weakly with the supported oxides while niobia forms new phases through solid state reactions with the supported oxides during catalytic operation that must account for its higher selectivity values towards acrylonitrile and higher specific rate of acrylonitrile formation per vanadium site.     

Active sites of Cu-ZSM-5 for the decomposition of acrylonitrile

The catalytic decomposition of acrylonitrile (AN) over Cu-ZSM-5 prepared with various Cu loadings was investigated. AN conversion, during which the nitrogen atoms in AN were mainly converted to N₂, increased as Cu loading increased. N₂ selectivities as high as 90–95% were attained. X-ray diffraction measurements (XRD) and temperature-programmed reduction by H₂ (H₂-TPR) showed the existence of bulk CuO in Cu-ZSM-5 with a Cu loading of 6.4 wt% and the existence of highly dispersed CuO in Cu-ZSM-5 with a Cu loading of 3.3 wt%. Electron spin resonance measurements revealed that Cu-ZSM-5 contains three forms of isolated Cu²⁺ ions (square-planar, square-pyramidal, and distorted square-pyramidal). The H₂-TPR results suggested that in Cu-ZSM-5 with a Cu loading of 2.9 wt% and below, Cu⁺ existed even after oxidizing pretreatment. The activity of AN decomposition over Cu/SiO₂ suggested that CuO could form N₂, but, independent of the CuO dispersion, nitrogen oxides (NO_x) were formed above 350 °C. Cu⁺ and the square-pyramidal and distorted square-pyramidal forms of Cu²⁺ showed low activity for AN decomposition. Temperature-programmed desorption of NH₃ suggested that N₂ formation from NH₃ proceeded on Cu²⁺, resulting in the formation of Cu⁺. The Cu⁺ ions were oxidized to Cu²⁺ at around 300 °C. Thus, high N₂ selectivity over Cu-ZSM-5 with a wide range of temperature was probably attained by the reaction over the square-planar Cu²⁺, which can be reversibly reduced and oxidized.     

丙烯腈吸收塔放空管道噪声控制

某石油化工总厂丙烯腈车间的吸收塔在放空负荷增大以后产生了较严重的噪声,对生产环境造成极大污染。为对丙烯腈吸收塔的放空管道实施噪声控制,改善工厂以及周边厂家的生产环境,进行了噪声控制方案设计及消声器设计。项目实施后,噪声绝对值降低了20分贝,噪声幅度降低达24％。     

Acrylonitrile-based copolymer membranes containing reactive groups: Surface modification by the immobilization of biomacromolecules

Asymmetric membranes fabricated from poly(acrylonitrile-co-maleic acid) (PANCMA) were immobilized with heparin and/or insulin to improve their surface properties. These biomacromolecule-immobilized PANCMA membranes were prepared by the amination of the membrane surface with ethylenediamine, followed by the reaction of the amino groups with heparin and/or insulin in the presence of 1-ethyl-3-(3-dimethyl amidopropyl) carbodiimide. The surface-modified membranes were analyzed by X-ray photoelectron spectroscopy to confirm the immobilization of the biomacromolecules. Morphological changes on the membrane surface and in the cross section were characterized by scanning electron microscopy. The surface hydrophilicity and hemocompatibility of the studied membranes were evaluated on the basis of water contact angle, platelets adhesion and cell attachment measurements. It was found that, after the immobilization of the biomacromolecules, the water contact angle and the amount of adhered platelets and macrophages on the membrane decreased significantly when compared with the nascent ones, indicating the improvement of surface hydrophilicity. Furthermore, the heparin immobilized membrane showed the best hemocompatibility among the corresponding membranes studied.     

GDX-102色谱柱测定T-103塔尾气中的丙烯腈

用GDX-102色谱柱测定T—103塔尾气中的丙烯腈，相对标准偏差为0．4094％。数据准确、可行。     

丙烷氨氧化制丙烯腈催化剂的助剂作用研究

在自制的一系列钒锑系催化剂上，考察了Ｐ２Ｏ５、Ｋ２Ｏ、ＳｎＯ２等助催化剂对丙烷氨氧化制丙烯腈催化剂的催化性能的影响，阐述了助剂对催化性能的作用机理。最后得到较佳的丙烯腈收率２６％～２８％。     

Synthesis of cyano-polycarbosilane and investigation of its pyrolysis process

Polycarbonsilane (PCS) is an important precursor of silicon carbide (SiC) fibers and ceramics. The ceramic yield of PCS is relatively low, about 60 %, which may bring some deficiencies in its applications. In this work, a novel precursor cyano-polycarbosilane (PCSCN) is synthesized by hydrosilylation reaction between PCS and acrylonitrile using a rhodium-containing catalyst, although acrylonitrile is generally not easy for hydrosilylation. After introducing tiny amounts of cyano (-C≡N) groups into the PCS molecules, the ceramic yield of PCSCN can increase largely to over 80 %. The ceramization mechanism of PCSCN is investigated by FTIR, TG, XPS, ESR, NMR, Raman and XRD analyses. It is found that some crosslinking structures in PCSCN are formed between SiH bonds and CN groups from about 200 ℃, which can be responsible for the high ceramic yield. The existence of a little more N, O and free C elements in the pyrolysis products may inhibit the growth of crystalline β-SiC. Moreover, the PCSCN precursor can also be melt-spun into continuous fibers by tailoring its molecular weight and softening point. The oxidized PCSCN fiber with relatively low oxygen content can be pyrolyzed without melting, and the final SiC fiber with an oxygen content as low as 8.5 % is obtained.     

丙烯腈装置副产氢氰酸的工业利用

氢氰酸是丙烯腈的副产品，综合利用氢氰酸将会提高丙烯腈装置的经济效益。介绍了几种利用氢氰酸合成其它化学品的工业生产方法，旨在使企业更多地了解氢氰酸的综合利用。     

紫外光引发淀粉接枝丙烯腈的溶剂效应

在紫外光引发条件下进行玉米淀粉与丙烯腈的接枝反应，考察了单溶剂、混合溶剂的种类及用量对接枝反应接枝率和接枝效率的影响，得到了光接枝反应过程中溶剂效应的一些规律．     

预辐照聚偏氟乙烯粉粒的丙烯腈接枝反应

报导辐照剂量、辐照后存储时间、反应温度等对预辐照聚偏氟乙烯粉粒丙烯腈接枝反应的影响，研究了各种添加剂的溶剂效应，并对接枝反应中出现的异常放热现象进行动态研究。讨论了接枝反应机理。