电石法生产聚氯乙烯过程中汞的流向及处理技术分析

汞是对环境有高度敏感性的重金属,汞污染已经成为全球高度关注的敏感议题。我国汞资源相对匮乏,对汞资源的过度消耗和汞污染是电石法生产聚氯乙烯(PVC)行业发展的巨大障碍。本文针对电石法生产PVC中的严重汞污染问题,分析了生产过程中汞的来源、流向,并且提出对应的处理技术,为电石法生产PVC中的汞污染防治提供思路。     

中美化工安全本科教育对比

针对中美2国高校化工安全教育的发展,对比2国化工安全本科教育在教育背景、专业课程和教学资源方面的差异。依据对比结果,分析我国化工安全本科教育存在的不足,提出从加强安全文化教育、推进化工专业认证和提高师资工程背景等方面促进我国化工安全本科教育的发展。     

小型简易电石爐生产电石的几个问题的商讨

小型簡易电石炉是指电石炉容量在1000千伏特安培以下,不需要冷却设备者。这种电石炉的特点是:构造簡单,操作容易,占地少,用料少,投資少,时間快,易于推广。现将我們搞小型简易电石炉生产电石初步获得的几点体会介绍如下: 一、电石生产的基本原理及工艺流程电石是把石灰和碳素原料(焦炭或无烟煤)放在电炉内熔融制成的,其反应如下: CaO 3C(?)CaC_2 CO—108,000千卡 (1) 根据(1)式,可知电石的生成反应,是一个吸收大量热的反应,也就是說,电石需在高温下才能生成。生成的温度是在1,800—2,200℃之间,現在都是利用电     

电石渣在煅烧/氯化反应中的HCl脱除特性研究

采用钙基废弃物———电石渣煅烧后脱除HCl。在煅烧/氯化反应器上研究脱氯反应温度、HCl体积分数、颗粒粒径和煅烧温度对电石渣脱氯性能的影响。结果表明,电石渣在700℃时取得最高氯化转化率;脱氯反应温度高于650℃后,电石渣氯化转化率均高于石灰石,电石渣高温脱氯更有优势。电石渣氯化转化率随反应气氛中HCl体积分数提高呈线性增长。随电石渣颗粒粒径增大,氯化转化率缓慢降低。高于900℃的煅烧温度不利于电石渣脱除HCl。煅烧后电石渣分布在2~10 nm的孔隙较多,氯化后分布在此孔径范围内的孔容和孔面积分别降低了56.2%和62.2%,2~10 nm孔隙是煅烧后电石渣吸收HCl的主要区域。     

建立绿色化学理念深化化工工艺学教学改革

为保证21世纪我国的可持续发展战略的实施,必须进行绿色化学教育.文章分析了"化工工艺学"课程中开展绿色化学教育的必要性与可行性;介绍了化工工艺学教学中开展绿色化学教育的改革与实践,以及绿色化学教育在培养和提高人才的全面素质与综合能力等方面的积极作用.绿色化学教育既是21世纪化学教育所面临的时代挑战,也是化工教育发展的一大机遇,关系着我国可持续发展战略目标的实现.     

电感耦合等离子体原子发射光谱法测定电石中铁、硅、铝、钛

电石是有机合成化学工业的基本原料,利用电石可以合成一系列的有机化合物,为工业、农业、医药等行业提供所需原料。工业电石的主要成分是碳化钙,其余为游离氧化钙、碳以及硅、镁、铁、铝的化合物和少量的磷化物和硫化物等。工业用电石纯度     

化学工程:从基础研究到工业应用

本文介绍了我国中长期发展规划中所制定的化学化工学科发展目标,综述了化学工程学科近十余年来在队伍建设、平台建设和国家级奖励等方面所取得的成果,列举了若干化学工程在传递与过程强化、化工分离过程、精细与药物化工、能源化工和材料化工领域从基础研究到工业化应用的例子和成果,展望了化学工程学科今后发展的方向及目标.     

电石制备过程中不同含钙化合物与焦炭的反应行为研究

针对粉状原料-氧热法电石生产新工艺的需求,通过程序升温法研究了多种粉状含钙原料与粉状焦炭直接反应制备电石的过程。结果表明,升温过程中CaCO3释放的CO2、Ca(OH)2和电石渣释放的H2O对焦炭的量和质的影响很小,CaCO3、Ca(OH)2和电石渣均可直接用于电石生产,电石生成反应自1 450℃开始,1 740℃左右达到峰值。CaSO4与焦炭在920℃左右反应形成CaS,在研究的温度范围内CaS不与焦炭反应。     

发展中的电子化工材料

本文介绍了国内外电子化工材料部分大类品种的现状及发展趋向,并提出至2000年发展我国电子化工材料的措施和建议。     

M/C3N4/AC (M=Au,Pt,Ru)催化乙炔与二氯乙烷耦合反应:双功能催化剂性能如何?

聚氯乙烯是世界上产量最大的通用塑料,在日常生活的诸多领域具有广泛应用.按照原料来源划分,聚氯乙烯的工业生产方法主要有基于煤炭的电石法和基于石油的"平衡法".我国有丰富的煤炭资源,因此,电石乙炔法是合成聚氯乙烯的主要途径.该方法采用乙炔与氯化氢在活性炭担载氯化汞催化剂上进行氢氯化反应得到聚氯乙烯的单体氯乙烯.然而,由于汞...     

乙炔羰基化反应催化剂:由均相到多相

基于非石油路线制备的乙炔小分子,其羰基化反应可制备大量高附值化学品,在CO排放的环境治理以及化学品应用方面有着十分重要的意义.本文主要概述了乙炔羰基化反应的催化剂由均相到多相的研究进展,总结了乙炔单/双羰基化催化剂种类及添加剂对反应活性的影响.基于反应机理分析提出调控结构敏感性因素(尺寸效应及形貌效应)制备高效催化剂的...     

Carboxylation of Acetylene without Salt Waste: Green Synthesis of C4 Chemicals Enabled by a CO2-Pressure Induced Acidity Switch

The inherent formation of salt waste in C−H carboxylations is a key obstacle precluding the utilization of CO₂ as C₁ building block in the industrial synthesis of base chemicals. This challenge is addressed in a circular process for the production of the C₄ base chemical dimethyl succinate from CO₂ and acetylene. At moderate CO₂ pressures, acetylene is doubly carboxylated in the presence of cesium carbonate. Hydrogenation of the C−C triple bond stabilizes the product against decarboxylation. By increasing the CO₂ pressure to 70 bar, the medium is reversibly acidified, allowing an esterification of the succinate salt with methanol. The cesium base and the hydrogenation catalyst are regenerated and can be reused. This provides the proof of concept for a salt-free route to C₄ chemicals from biogas (CH₄/CO₂). The origin of this reversible acidity switch and the critical roles of the cesium base and the NMP/MeOH solvents were elucidated by thermodynamic modeling.     

甘薯象鼻虫信息素(E)-2-丁烯酸-(Z)-3-十二烯基酯的全合成

性信息素;甘薯象鼻虫信息素(E)-2-丁烯酸-(Z)-3-十二烯基酯的全合成     

Electrodeposited Sn-based Catalysts for CO2 Electroreduction

Electrochemical CO2 reduction reaction(CO2RR) has been considered as a feasible avenue for simultaneous conversion of renewable energy and CO2. Economic and technical analysis suggests that the production of valuable C1 chemicals such as formic acid and CO is the most economically practicable route for CO2RR. This perspective summarizes the performance of electrodeposited Sn-based catalysts for C1 chemicals production and the relative mechanism of CO2RR. Further fundamental understanding and industrial applications of electrodeposited Sn-based catalysts in CO2 electrolyzer device are also discussed.     

1,2-Difunctionalization of Acetylene Enabled by Light

Although the direct conversion of gaseous acetylene into value-added liquid commodity chemicals is becoming increasingly attractive, the majority of the established methodologies are focused on cross-coupling, hydro-functionalization, and polymerization. Herein, we describe a 1,2-difunctionalization method that inserts acetylene directly into readily available bifunctional reagents. This method provides access to diverse C2-linked 1,2-bis-heteroatom products in high regio- and stereoselectivity along with opening up previously unexplored synthetic directions. In addition, we demonstrate this method's synthetic potential by converting the obtained products into diverse functionalized molecules and chiral sulfoxide-containing bidentate ligands. Using a combination of experimental and theoretical methods, the mechanism for this insertion reaction was investigated.     

Recovery of organic acids from fermentation broths

Rising concerns over the use of fossil resources have generated renewed interest in the production of commodity chemicals via fermentation. Organic acids are a particularly attractive target because their functionality enables downstream catalytic upgrading to a variety of compounds. In this article, we survey how common technical issues are addressed in the recovery schemes for several organic acids. We present results for the recovery of acetate using a new method based on amine complexation. Our reactive separation scheme produces a high-purity product, is energy efficient, and avoids the coproduction of a waste salt coproduct, all prerequisites for a large-scale production process.     

The influence of interunit carbon–carbon linkages during lignin upgrading

The cleavage of β-O-4 linkages in lignin can generate monomers with a phenyl propane structure that can easily be upgraded into valuable hydrocarbon biofuels and renewable aromatic chemicals. High-yield lignin monomer production from extracted (or technical) lignin that is produced in a practical way could facilitate the productivity and profitability of biomass conversion processes. However, interunit carbon–carbon (C–C) linkages present in native lignin or formed during lignin condensation in biomass pretreatments dramatically reduce lignin monomer yields. Here, we present a perspective on biological and chemical strategies that have been successfully used to reduce the formation of C–C linkages in native or technical lignin. We analyze the mechanisms involved in these strategies and offer our views on improving the quality of technical lignin resulting from biomass conversion in order to achieve high-yield lignin monomer production.     

Improvement of tritium counting sensitivity by using completely labelled ethane as internal gas sample for the proportional counter

Further improvement of the counting sensitivity of a proportional gas counter is obtained by using ethane synthesized from acetylene and hydrogen, where thesample of tritiated water is used for acetylene production as well as for hydrogen generation. In this way all six hydrogen atoms of the filling gas molecule arise from the active sample. The advantage of this sample preparation procedure is obvious especially in the case of low-level tritium measurements.     

Plasma Thermal Conversion of Methane to Acetylene

This paper describes a re-examination of a known process for the direct plasma thermal conversion of methane to acetylene. Conversion efficiencies (% methane converted) approached 100% and acetylene yields in the 90–95% range with 2–4% solid carbon production were demonstrated. Specificity for acetylene was higher than in prior work. Improvements in conversion efficiency, yield, and specificity were due primarily to improved injector design and reactant mixing, and minimization of temperature gradients and cold boundary layers. At the 60-kilowatt scale cooling by wall heat transfer appears to be sufficient to quench the product stream and prevent further reaction of acetylene resulting in the formation of heavier hydrocarbon products or solid carbon. Significantly increasing the quenching rate by aerodynamic expansion of the products through a converging–diverging nozzle led to a reduction in the yield of ethylene but had little effect on the yield of other hydrocarbon products. While greater product selectivity for acetylene has been demonstrated, the specific energy consumption per unit mass of acetylene produced was not improved upon. A kinetic model that includes the reaction mechanisms resulting in the formation of acetylene and heavier hydrocarbons, through benzene, is described.     

The kinetics and mechanism of the reduction of short-bond compounds in aqueous solutions of salts containing bivalent chromium

The kinetics of the reduction of acetylene and fumaric acid in aqueous and aqueous alcoholic solutions by chromous chloride have been investigated.Reversible formation of a complex of Cr²⁺ with acetylene has been observed, and this is apparently an intermediate product in the production of acetylene. The rate of the reduction reaction in both cases is proportional to the square of the chromous ion concentration, and to the concentration of the unsaturated compound. In the reduction of acetylene, the rate of the reaction is proportional to the concentration of the hydrogen ion; in the reduction of fumaric acid the action is somewhat retarded when hydrogen ion concentration is increased.A mechanism for the reaction is proposed, in which in the rate-determining stage hydrogen is transferred to the short bond in the complex made up of two ions of chromium and the unsaturated compounds.