Mechanochemical-treated Cr-promoted Vanadyl Pyrophosphate Catalyst for n-Butane Oxidation to Maleic Anhydride

Abstract

Cr-promoted vanadium phosphate (VPO) catalyst was synthesized by mechanotreating VOHPO₄·0.5H₂O in cyclohexane for 2 hr using a high energy planetary ball miller followed by calcination in a flow of n-butane/air mixture at 673 K. The physico-chemical properties of the sample were investigated by several characterization techniques such as BET, XRD, redox titration, SEM, and TPR. The data were compared to the unmilled material. BET surface area measurement of the milled catalyst showed that it possesses higher surface area (13.2 m² g^?1) compared to the unmilled catalyst (6.4 m² g^?1). Milling also caused a slight increment in the average oxidation state of vanadium as well as the percentage of V⁵⁺ oxidation state. XRD pattern of the milled material revealed that the major diffraction peaks were broadened thus indicating a reduction of particle size. SEM micrographs showed the lost in the blossom morphology and the formation of layer packages, with more circular particles in the milled catalyst. The amount of active lattice oxygen species being removed from V⁴⁺-O^? pairs increased significantly for mechanochemical treated Cr-doped VPO catalyst leads to the enhancement of the catalytic activity for n-butane oxidation to maleic anhydride.     

丁烷异构化工艺的能量利用及其优化设计

简要介绍了丁烷异构化工艺的发展现状及典型的异构化工艺流程,利用Aspen Plus软件模拟,进行了能量的集成利用及重点换热器的设计优化,分析比较了能耗和成本的节省情况.在产品分离部分,对稳定塔和异丁烷塔进行热耦合,节省了低压蒸汽消耗,通过适当升高稳定塔压力实现了更佳的节能效果.在异构化反应部分,优化反应进出料换热,采用...     

Transient kinetics of n‐butane partial oxidation at elevated pressure

A transient Mars‐van Krevelen type kinetic model was developed for n‐butane partial oxidation over vanadyl pyrophosphate (VPP) catalyst. The model validity was verified over a relatively wide range of redox feed compositions as well as higher reactor pressure (410 kPa). Oxygen and n‐butane conversion increased with higher pressure while maleic anhydride (MA) selectivity decreased by as much as 20%. However, the overall MA yield was enhanced by up to 30%. High pressure maintains the catalyst in a higher oxidation state (as long as there is sufficient oxygen in the gas phase) and as a consequence, the catalytic activity is improved together with MA yield. High pressure also affects the redox reaction rates and activation energies. © 2012 Canadian Society for Chemical Engineering     

正丁烷氧化法顺丁烯二酸酐生产工艺尾气的循环利用

为回收利用尾气中的未反应原料并减少环境污染,中国石油吐哈油田公司石油天然气化工厂对２万ｔ／ａ正丁烷氧化法顺丁烯二酸酐生产装置进行了尾气循环利用技术改造。计算结果表明,装置的尾气极限循环率为４５．２％,首次技术改造后只实现了１５．０％的循环利用,潜力尚较大。１５．０％尾气循环利用后,正丁烷单耗［ｍ（正丁烷）／ｍ（顺丁烯二酸酐）］由１．１７０ｔ／ｔ下降到１．１４５ｔ／ｔ,正丁烷节约量为３３５ｔ／ａ。     

海藻酸衍生物对棉织物抗皱整理工艺研究

将海藻酸丙二醇酯(PGA)与丁烷四羧酸(BTCA)混合用于棉织物的抗皱整理/改变PGA用量、BTCA用量、焙烘温度及焙烘时间,通过测试整理后织物的折皱回复角、白度以及断裂强力等性能,确定了最佳工艺:PGA 15g/L,BTCA 40 g/L,190℃焙烘150 s.整理后棉织物的折皱回复角、强力保留率及白度均较好,说明PGA与BTCA混合对棉织物进行抗皱整理是可行的.     

亚临界丁烷制备豆粕及其蛋白氧化稳定性研究

采用亚临界丁烷对大豆粉脱油制得豆粕(DSF-B),并与正己烷制备豆粕(DSF-H)比较,对分离蛋白得率及热变性、豆粕残余极性脂和在贮藏过程中蛋白的氧化进行分析。DSF-B的蛋白得率(32.1%)比DSF-H高(约6%),蛋白热变性二者一致,且11S变性温度低于工业白豆片。残余极性脂分析,DSF-B比DSF-H总量低、磷脂含量高,脂肪酸组成有差异。模拟贮藏试验表明,DSF-B在贮藏中蛋白更易被氧化,这可能与极性脂的组成有关。亚临界萃取技术无高温处理、可选溶剂多样,可开发应用于大豆等植物蛋白制品。     

Effects of ignition advance on a dual sequential ignition engine at lean mixture for hydrogen enriched butane usage

In this study, the effects of ignition advance on dual sequential ignition engine characteristics and exhaust gas emissions for hydrogen enriched butane usage and lean mixture were investigated numerically and experimentally. The main purpose of this study is to reveal the effects of h-butane application in a commercial spark ignition gasoline engine. One cylinder of the commercially dual sequential spark ignition engine was modeled in the Star-CD software, taking into account all the components of the combustion chamber (intake-exhaust manifold connections, intake-exhaust valves, cylinder, cylinder head, piston, spark plugs). Angelberger wall approximation, k-ε RNG turbulence model and G-equation combustion model were used for analysis. In the dual sequential spark ignition, the difference between the spark plugs was defined as 5° CAD. At the numerical analysis; 10.8:1 compression ratio, 1.3 air-fuel ratio, 2800 rpm engine speed, 0.0010 m the flame radius and 0.0001 m the flame thickness were kept constant. The hydrogen-butane mixture was defined as 4%–96% by mass. In the analysis, the optimal ignition advance was determined by the working conditions. In addition, the effects of changes in ignition advance were examined in detail at lean mixture. For engine operating conditions under investigation, it has been determined that the 50° CAD ignition advance from the top dead center is the optimal ignition advance in terms of engine performance and emission balance. It has also been found that the NO_x formation rises up as the ignition advance increases. The BTE values were approximately 12.01% higher than butane experimental results. The experimental BTE values for h-butane were overall 3.01% lower than h-butane numerical results.     

南极磷虾脂质的亚临界提取及磷脂分析

研究了南极磷虾脂质的亚临界丁烷提取工艺。测定了南极磷虾脂质的酸值、过氧化值、氟含量、生育酚含量、虾青素含量、磷脂含量及磷脂种类组成、脂肪酸组成。结果表明,通过单因素试验确定了亚临界丁烷提取南极磷虾脂质的较佳工艺条件为:动态提取时间120 min(单次提取时间30min、提取4次)、提取压力1.0 MPa、提取温度40℃;在较佳工艺条件下南极磷虾脂质提取率为21.39%;提取的南极磷虾脂质的酸值(KOH)10.6 mg/g,过氧化值3.01 meq/kg,虾青素含量248.4mg/kg,生育酚含量67.7 mg/kg,磷脂含量28.68%,其中磷脂中磷脂酰胆碱占71.20%;磷脂酰胆碱中脂肪酸组成与甘三酯的基本一致,但磷脂酰胆碱中EPA和DHA含量明显高于甘三酯的。     

Oxidative Stability of Papaya Seed Oil From Hainan/Eksotika Obtained by Subcritical and Supercritical Carbon Dioxide Extraction

Papaya seed is a good source of edible oil with considerable antioxidant activity. Here, papaya seed oil (PSO) of Hainan/Eksotika variety was obtained by subcritical butane extraction (SBE) and supercritical carbon dioxide extraction (SCDE), and its yields, physicochemical properties, oxidative and thermal stability, and chemical and microscopic structures were compared. The results showed that SBE‐PSO had a higher yield (25.88 ± 0.29% vs. 19.47 ± 0.92%), but a lower melting point compared to SCDE‐PSO. Molecular structures indicated that there was no oxidative degradation during SBE and SCDE. Both SBE and SCDE caused significant structural changes of seed tissues. In addition, aldehyde composition analysis using high performance liquid chromatography (HPLC) showed that SBE‐PSO had fewer octanal, nonanal, 2‐decenal, and 2‐undecenal contents than SCDE‐PSO. All these results proved that SBE‐PSO exhibited superiority on the oxidative stability compared to SCDE‐PSO. It indicated that SBE was a superior method to obtain antioxidant edible oil with good stability.