渣油加氢裂化反应中油溶性催化剂的抑焦性能

以辽河常压渣油为研究对象,通过高压釜模拟渣油加氢裂化反应,对不同油溶性催化剂体系反应后的生焦量、生焦状况及产物进行分析,深入研究渣油加氢裂化反应中油溶性催化剂的抑焦性能.研究表明,随着活性金属含量的增大,油溶性单金属Co催化剂和Ni催化剂的生焦量减少,Co - Fe或Ni - Fe复配体系具有协同效应,抑焦性能增强,由...     

Effect of alumina addition on properties of glass/ceramic composite

Abstract

A series of glass/ceramic composites were prepared from pyrex borosilicate glass with silica. The effects of 15 vol.-% alumina addition on cristobalite formation in this system have been studied. Cristobalite formation in the composites has been found to decrease with addition of alumina, which may be attributed to a strong coupling reaction between Al³⁺ from alumina and K⁺ from pyrex borosilicate glass. The resulting glass/ceramic composites containing alumina have low thermal expansion coefficient owing to the presence of a lower amount of cristobalite in the glass matrix. The formation of cristobalite limits the efficiency of the ceramic substrate when used in circuit boards.     

Corrosion of a Borosilicate Glass by Orthophosphoric Acid

A borosilicate glass was resistant to orthophosphoric acid at 95°C, whereas considerable corrosion occurred at higher temperatures. Tenacious crystal formation provided a barrier against further attack, but also produced stress resulting in spontaneous glass breakage. The acid-glass reaction is attributed to acid dehydration and consequent transformation to aggressive pyrophosphate.     

水煤浆气化炉内飞灰的形成机理

基于实验室规模的多喷嘴对置式水煤浆气化炉,利用SEM、马尔文激光粒度仪和XRD表征气化炉内飞灰的粒径分布和组成,并分析了气化炉内飞灰的形成机理。结果表明,喷嘴平面处飞灰与气化炉出口处飞灰的粒径分布及化学组成存在显著差异,不同气化阶段飞灰的形成机理也不同。气化燃烧阶段飞灰的形成机理为部分固定碳燃烧和外在矿物转化,而在焦炭气化反应阶段,飞灰的形成机理为焦炭破碎和内在矿物释放及转化。     

Photo-mediated copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) “click” reactions for forming polymer networks as shape memory materials

The formation of polymer networks polymerized with the Copper (I) – catalyzed azide – alkyne cycloaddition (CuAAC) click reaction is described along with their accompanying utilization as shape memory polymers. Due to the click nature of the reaction and the synthetic accessibility of azide and alkyne functional-monomers, the polymer architecture was readily controlled through monomer design to manipulate crosslink density, ability for further functionalization, and the glass transition temperature (55–114 °C). Free strain recovery is used to quantify the shape memory properties of a model CuAAC network resulting in excellent shape fixity and recovery of 99%. The step growth nature of this polymerization results in homogenous network formation with narrow glass transitions ranges having half widths of the transition close to 15 °C for these materials resulting in shape recovery sharpness of 3.9%/°C in a model system comparable to similarly crosslinked chain growth polymers. Utilization of the CuAAC reaction to form shape memory materials opens a range of possibilities and behaviors that are not readily achieved in other shape memory materials such as (meth) acrylates, thiol-ene, thiol-Michael, and poly(caprolactone) based shape memory materials.     

高温悬浮态下硫铁矿的氧化特性研究

硫铁矿的高温氧化是引起水泥生产过程中产生SO2的主要原因。采用一维炉开展了高温悬浮态下硫铁矿氧化的实验研究,并对氧化产物做了X射线衍射（XRD）分析和烧失量检测。XRD分析表明,FeS2在300 ℃时尚未发生氧化反应,从400 ℃开始出现Fe2O3的衍射峰,且随着温度升高,FeS2的衍射峰强度逐步减弱,Fe2O3衍射峰强度逐步增强。在400~800 ℃时,FeS2的氧化产物仅为Fe2O3。基于烧失量的计算表明,在10 s反应时间内,FeS2在300 ℃几乎没有发生氧化,这和XRD检测结果一致。在400 ℃和600 ℃时FeS2氧化率分别达到了50%和85%,800 ℃时达到了92%。将上述结果应用于水泥生产过程,表明在C1~C4预热器中,约64%的FeS2发生了氧化。     

FeS/过硫酸盐体系元素价态转化及其降解有机物机制

由于FeS表面的还原性Fe(Ⅱ)和S(-Ⅱ)都可以作为电子供体，可有效促进有机化合物的还原转化与过硫酸盐的活化，FeS活化过硫酸盐体系在土壤地下水有机污染原位修复中显示出巨大的应用发展潜力。本文综述了FeS活化过硫酸盐产生活性自由基的内在机理及影响体系反应效率的关键因素；总结了活化过程中FeS表面元素转化机制和转化提高途径；较系统地梳理了FeS活化过硫酸盐体系对卤代烃、石油烃、多环芳烃类复杂有机化合物的降解过程机制。最后对研究中存在的问题及在场地污染修复应用中应重点关注的问题进行了展望，应重视修复中产生的过硫酸根、硫酸根及降解中间产物对环境的影响，在实际应用中需要根据不同的环境条件评估FeS/过硫酸盐体系的有效性，并且制定不同的修复策略。     

Fabrication of Continuous-SiC-Fiber-Reinforced SiAlON-Based Ceramic Composites by Reactive Melt Infiltration

A technique for fabrication of β'-SiAlON-based ceramics in three-dimensional woven fabrics of BN-coated SiC (Hi-Nicalon™) fibers was developed by reactive melt infiltration in a controlled N₂ atmosphere. β'-SiAlON was produced in situ by the reaction of β-Si₃N₄, AlN, and Y-Al-Si-O molten glass. The wettability of the fibers with the molten glass was improved by infiltration and pyrolysis of perhydropolysilazane, resulting in fully dense matrix composites. The reaction between the fiber and molten glass could be depressed by increasing the N₂ partial pressure during the melt infiltration. The inhibition of the interfacial reaction may be related to the formation of carbon and oxynitride on the SiC fiber, in agreement with thermodynamic calculations as a function of N₂ partial pressure. The fabricated composites had a high ultimate flexure strength and a large work of fracture at room temperature. Degradation of the mechanical performance of the composites was small, even at 1773 K in an argon atmosphere.     

硫化焙烧锡铁矿脱锡

为实现锡铁矿的资源化利用,采用硫化焙烧法对其进行处理。以热力学分析为基础,结合实验研究对锡铁矿的硫化焙烧反应特征进行了探索。结果表明,较高焙烧温度下,锡硫化挥发物相主要是SnS和SnO,Sn和SnO2的挥发作用相对较小,同等条件下SnO比SnO2和Sn硫化反应趋势大。焙烧过程控制CO浓度低于22%且温度高于873 K时,SnO2可选择性还原成SnO;过程中,FeS2可分解为FeS和S2,S2的硫化作用大于FeS。锡铁矿硫化反应受S2、SO2及SnS的扩散速率控制,界面化学反应不起决定性作用。焙烧后铁物相由赤铁矿相转变成磁铁矿相,可采用磁选法回收其中铁资源,为高效回收锡铁矿中铁资源提供了一种新思路。     

Enhanced thermoelectric power generation performance of mixed-phase FeS/FeS2 nanostructures by controlling the reaction time duration

Thermoelectric materials can convert heat energy into electricity and could be the future of sustainable energy demand. In the current work, we have successfully improved the thermoelectric performance of hydrothermally synthesized mixed-phase pyrite nanostructures. For this, samples with different FeS/FeS₂ phase ratios were synthesized by controlling the reaction time duration. XRD data confirms the formation of mixed phases of FeS and FeS₂, which increases with the increase in reaction time, while the Raman spectroscopy results verify the argument. Scanning electron microscope images represents the formation of nanoporous morphology. For thermoelectric properties, both the Seebeck coefficient (44–69 μV/^°C) and electrical conductivity (33–48 S/cm) were found to be improved with the increase in reaction time (12–48h). This simultaneous enhancement in Seebeck coefficient and electrical conductivity was associated with the energy filtering effect at the crystal interface leading to the improvement in thermoelectric power factor to 2.28 × 10^?5 Wm^?1C^?2 (at 25^oC) for 48h sample.     

HNO3催化氧化煤系硫铁矿生产聚合硫酸铁方法与装置研究

提出一套利用 HNO3催化氧化煤系硫铁矿 (Fe S2 )生产聚合硫酸铁 (PFS)的反应系统。它包括 Fe S2 氧化反应器、Fe2 氧化反应器、循环泵和射流器等。利用该反应系统实现了 HNO3及其氧化 Fe S2 放出 NOx和引入 O2 氧化 Fe S2 ,生产 Fe SO4和 H2 SO4 ,同时用 NOx和 O2 催化氧化 Fe SO4 生产聚合硫酸铁的目的。该方法具有 HNO3用量少、系统密封、无污染、催化剂可循环使用、反应速度快、经济效益和环保效益好等特点。     

焦化汽油贮罐中的硫化铁自燃机理与预防

硫化氢的腐蚀问题广泛地存在于石油、天然气和其它一些工业中。硫化氢腐蚀后生成硫化铁，硫化铁自燃可引发火灾．国内的几起重大的炼油厂火灾事故几乎均由硫化铁的自燃引起，本文分析了硫铁矿ＦｅＳ２的形成及其自燃机理，并对如何预防此类事故的再发生作了一些有益的探讨．     

焦化汽油贮藏中的硫化铁自燃机理与预防

硫化氢的腐蚀问题广泛地存在于石油，天然气和其它一些工业中，硫化氢腐蚀后生成硫化铁，硫化铁自燃可引发火灾，国内的几起重大的炼油厂火灾事故几乎均由硫化铁的自燃引起，本文分析了硫铁矿FeS2的形成及其自燃机理，并对如何预防此类事故的再发生作了一些有益的探讨。     

Synthesis of Ti2SC Phase Using Iron Disulfide or Iron Sulfide Post‐Treated with Acid

This study reports a viable method for the synthesis of Ti₂SC phase using iron disulfide or iron sulfide as sulfur source and a post‐treatment with acid. The reaction routes to Ti₂SC phases starting from two different chemical compositions of 2Ti–FeS₂–2TiC and Ti–FeS–TiC were in detail explored and compared through the analysis of X‐ray diffraction, thermogravimetry/differential scanning calorimetry, and scanning electron microscopy results. Unlike the Ti–FeS–TiC composition, the reaction route from 2Ti–FeS₂–2TiC composition contained an extra decomposition step in which FeS₂ transformed to activated FeS and released molecular state sulfur at temperature around 500°C. The latter at this temperature could successfully trigger the reaction of Ti–S–TiC to form Ti₂SC phase, which was an analogous self‐propagating high‐temperature synthesis with a high transient temperature. On the contrary, only trace of Ti₂SC phase could be obtained at temperature as high as 1200°C from the Ti–FeS–TiC composition. The main impurity phases from these iron disulfide reactant systems were Fe and FeS, and they could be easily purified by dissolution in H₂SO₄ solution, which resulted in Ti₂SC phase with a minor TiC phase in the final product.     

Fe/γ-Al2O3催化剂上CO同时还原NO和SO2研究

研究了不同载体(γ-Al₂O₃、HZSM-5、TiO₂、SiO₂和MgO)负载Fe催化剂上CO还原NO反应及CO同时还原NO和SO₂反应。结果表明,Fe/γ-Al₂O₃催化剂对CO与NO反应具有良好的催化活性,但随着反应时间的延长,催化剂很快失活;在CO和NO反应中加入SO₂,可以明显改善Fe/γ-Al₂O₃催化剂对CO还原NO反应的活性稳定性;O₂和H₂O对催化剂活性的影响较大,CO₂对催化剂的影响较小。XRD结果表明,FeS₂是催化剂的活性中心,在CO与NO反应后,FeS₂转变为催化惰性的Fe₇S₈而导致催化剂活性下降;在CO与NO及SO₂反应体系中引入O₂后,Fe/γ-Al₂O₃催化剂上的活性组分FeS2被氧化为Fe₂O₃,导致催化剂失活。     

Effect of siderite in coal on reductive pyrolytic analyses

The effect of the presence of siderite (FeCO₃) in coal on the atmospheric pressure–temperature programmed reduction (AP–TPR) analysis of coal is studied. Siderite is added to demineralised Maritza Iztok (lignite) and raw Nowy Wirek (high volatile bituminous) coal before analysis. Results show an extra troilite FeS peak in the AP–TPR profiles for both siderite doped coals. The mechanism of H₂S capture by siderite is discussed on the base of a model reaction. Additionally, the formation of troilite from the pyrite present in the initial coal during the AP–TPR experiment was monitored by scanning electron microscopy with an energy dispersive X-ray analyser (SEM–EDX). During AP–TPR analysis the evolving H₂S is captured by FeO or FeCO₃ and FeS is formed. These phenomena disturb the AP–TPR profiles as well as the sulphur recovery.     

Effect of MgO Addition on the Bondability and Interfacial Reaction between Dielectric and Glass-Ceramics for the Fabrication of Multi-Component Ceramic Substrates

Bondability and interfacial reaction between dielectric and insulator layers have been examined to obtain a basic understanding of bonding mechanisms. Lead-containing complex perovskite was used as a dielectric material. Two kinds of glass-ceramics were used as insulator material; lead borosilicate glass containing Al_2O3 (insulator A) and the same containing Al₂O₃ and M_gO (insulator B). Dielectric and insulator layers did not bond when insulator A was used. When insulator B was used, however, strong bonding was achieved between the two layers by firing the powder compacts at temperatures between 800° and 1000°C. Addition of M_gO to lead borosilicate glass increased the thermal expansion coefficient to that of the dielectric and enhanced the formation of reaction layers, resulting in good bonding. Two reaction layers were identified. The main reaction products were enstatite and bredigite for one layer contacting the dielectric, and enstatite and a compound with the same diffraction pattern as that of faujasite for the other layers contacting insulator B.     

Curing of epoxidized linseed oil: Investigation of the curing reaction with different hardener types

The effect of the hardener type and amount on the curing reaction and the resulting thermal and mechanical performance characteristics of epoxidized linseed oil are studied in detail. The analysis of the curing mechanism reveals that due to steric hindrance, side reactions and/or fast gelation, the optimal mixing ratio of bio-based epoxy resins and hardeners has to be determined experimentally and cannot be calculated. The investigated thermosets exhibit a glass transition temperature of 12, 54, and 145°C after curing. The overall mechanical performance of the resulting resin ranges from soft and flexible to stiff and rigid, depending on the hardener type applied, which can be utilized in the formation of epoxy composites and coatings.     

Physical and microstructural aspects of iron sulfide degradation in concrete

The microstructural aspects of iron sulfide degradation in dam concrete were investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) in both dam concrete samples and laboratory concrete. The results show that iron sulfide inclusions with a diameter of a few micrometers in the aggregates are reactive and appear to generate expansion first in the aggregates and consequently in the cement paste. The expansion from the iron sulfides is a consequence of the increase in volume of the reaction products formed. The types of iron sulfide present in the aggregate, mainly pyrrhotite (FeS) and pyrite (FeS₂), show similar reaction behavior in the aggregates. The released sulfate can lead to a secondary ettringite formation in the concrete matrix, but the degradation associated with this appears to be minor. The reaction of the iron sulfides was found to be very slow even when laboratory samples were exposed to elevated temperatures.     

Reactions of iron sulphides in simulated stack gases

The rates of production and consumption of SO₂ by the reactions of O₂, SO₂, and mixtures of O₂ and SO₂ in simulated stack gases with fixed and fluidised beds of FeS prepared from pyrite were determined over the temperature range 800 to 950 °C. The rates of production of SO₂ by reaction of Fe₂O₃ with FeS in different gas systems were also determined. The rate controlling factors were derived for each reaction.