Separation of Benzene and Cyclohexane by Batch Extractive Distillation

Azeotropic liquid mixture cannot be separated by conventional distillation. But extractive distillation or combination of the two can be valid for them. An experiment to separate benzene and cyclohexane by batch extractive distillation was carried out with N, N-dimethylformide （DMF）, dime- thyl sulfoxide （DMSO） and their mixture as extractive solvent. The effect of the operation parameters such as solvent flow rate and reflux ratio on the separation was studied under the same operating conditions. The results show that the separation effect was improved with the increase of solvent flow rate and the reflux ratio; all the three extractive solvents can separate benzene and cyciohexane, with DMF being the most efficient one, the mixture the second, and DMSO the least. In the experiment the best operation conditions are with DMF as extractive solvent, the solvent flow rate being 12.33 mUmin, and the reflux ratio being 6. As a result, we can get cyclohexane from the top of tower with the average product content being 86.98%, and its recovering ratio being 83.10%.

Modeling of Pervaporation Separation Benzene from Dilute Aqueous Solutions Through Polydimethylsiloxane Membranes

A modified solution-diffusion model was established based on Flory-Huggins thermodynamic theory and Fujita's free volume theory. This model was used for description of the mass transfer of removal benzene from dilute aqueous solutions through polydimethylsiloxane (PDMS) membranes. The effect of component concentration on the interaction parameter between components, that of the polymer membrane on the selectivity to benzene, and that of feed concentration and temperature on the permeation flux and separation factor of benzene/water through PDMS membranes were investigated. Calculated pervaporation fluxes of benzene and water were compared with the experimental results and were in good agreement with the experimental data.

Numerical study of n-heptane/benzene separation by thermal diffusion column

In this article,numerical simulations are performed to investigate the performance of the thermal diffusion column for the separation of n-heptane/benzene mixture.The present work tried to optimize column by analyzing significant parameters such as feed flow rate,temperature and cut.In order to obtain the hydrodynamic and temperature and mass distribution inside thermal diffusion column,computational fluid dynamic(CFD) method is applied to solve the Navier-Stocks equations.Numerical simulations are conducted to study the main parameters in both stationary and time-dependent conditions.By using the separation work unit as a function of cut,the optimal cut for maximum SWU occurs within a limited range of 0.47-0.5 for feed rate between 0.5 and 4 g min^-1.Our findings reveal that the optimum feed rate in the range of optimum cut is about 1 g min^-1.In transient study,results show that the best cut for reaching to steady-state condition is θ=0.5.

Highly efficient separation of benzene+cyclohexane mixtures by extraction combined extractive distillation using imidazolium-based dicationic ionic liquids

Benzene(BEN)and cyclohexane(CYH),which have very close boiling points and a binary azeotrope,are the most difficult binary components in the separation of aromatic and non-aromatic hydrocarbons.This study further explored the separation mechanism and industrial application prospects of BEN+CYH mixtures separated by a dicationic ionic liquid(DIL)[C_(5)(MIM)_(2)][NTf_(2)]_(2) based on experimental research.The calculation results of the Conductor-like Screening model Segment Activity Coefficient(COSMO-SAC)model show that selectivity and solvent capacity of the DIL are significantly improved.The effects of different anions and cations on the micro-structure distribution and diffusion behavior of BEN+CYH system were investigated by quantum chemistry(QC)calculations and molecular dynamics(MD)simulations.The results indicate that the anion[NTf_(2)]_(2)has low polarity,uniform charge distribution,and a dual role of hydrogen bonding andπ-πbonding,and the cation[C_(5)(MIM)_(2)]^(2+) has stronger interaction with BEN and higher selectivity than conventional cations.The liquid-liquid extraction and extractive distillation(LLE-ED)process using an optimized 65 mol/mol DIL+35 mol/mol H_(2)O mixed solution as the extractant was proposed,which solved the problem of low product purity in the LLE process and high energy consumption in the ED process.Under the best operating conditions,the purity of CYH product was 99.9%,the purity of BEN product was 99.6%,the recovery rate of BEN reached 99.9%,and the recovery rate of DIL reached 99.9%.The heat-integrated LLE-ED process reduced total annual cost by 21.6%,and reduced CO_(2) emissions by 48.0%,which has broad industrial application prospects.

Boron separation by adsorption and flotation with Mg-Al-LDHs and SDBS from aqueous solution

Layered double hydroxides(LDHs)have been shown to be effective adsorbents for boron.However,solid-liquid separation is still a problem when separating boron from industrial radioactive waste liquid.In this research,three types of Mg-Al-LDHs including Mg-Al-LDH(NO_(3)^(-)),Mg-Al-LDH(Cl^(-))and Mg-Al-LDH(SO_(4)^(2-))were applied to adsorb boron,and moreover sodium dodecylbenzenesulfonate(SDBS)was used to float the LDH particles from aqueous solution after boron adsorption.The results showed that 60 min was sufficient for the equilibrium adsorption of the three LDHs.The boron adsorption capacity of three LDHs was determined as follows:Mg-Al-LDH(NO_(3)^(-))>Mg-Al-LDH(Cl^(-))>Mg-Al-LDH(SO_(4)^(2-)),and was 2.0,0.98 and 0.2 mmol·g^(-1),each ranging from 0 to 80 mmol·L^(-1)with the initial boron concentration.The efficiency of boron removal by Mg-Al-LDH(NO_(3)^(-))and SDBS can reach up to 89.7%.Furthermore,the boron flotation mechanism of SDBS and LDHs has been studied,since SDBS as a flotation agent can react with LDHs and penetrate into the interlayer of LDHs in addition to electrostatic attraction.Therefore,LDHs in solution can be floated onto the foam layer to be separated from the solution,and the clarified solution was obtained.The method is simple and promising for boron removal from aqueous solution.

Hydrogen-bonding-driven self-assembly nonporous adaptive crystals for the separation of benzene from BTX and cyclohexane

Benzene is a volatile organic compound that can seriously harm human health,while it can serve as a precursor to produce chemicals of more complex structures in chemical industry.Capturing benzene using adsorbents is of great importance for human health,when the separation of hydrocarbons including benzene from crude oil was referred to as one of the“seven chemical separations to change the world”.In this work,we reported the efficient and selective separation of benzene from BTX and cyclohexane by hydrogen bonding self-assembly nonporous adaptive crystals AdaOH for the first time under mild and user-friendly conditions.Separation of benzene and cyclohexane(v/v=1:1)can be achieved by AdaOH with a purity of benzene up to 96.8%.Separation of BTX(v/v;benzene:toluene:o-xylene:m-xylene:pxylene=1:1:1:1:1)can be achieved by AdaOH with a purity of benzene increased from 20%to 82.9%.Our results suggest that separation of benzene using the activated AdaOH as a non-porous adaptive crystal for selectively and efficiently capturing benzene can solve the challenge in separation of benzene from other chemicals such as cyclohexane in chemical industry,and can be helpful for removal of benzene that is released from the vehicles to air.The advantages of commercially availability,easy preparation,high separation efficiency and selectivity for benzene might endow this material with enormous potential for practical uses in areas like petrochemical industry.

Separation Properties of a New Polysiloxane-Anchored β-Cyclodextrin Derivative as Gas Chromatography Stationary Phase

A new capillary gas chromatography stationary phase, monokis (2,6 di O benzyl 3 O propyl (3’)) hexakis(2,6 di O benzyl 3 O methyl) β CD bonded polysiloxane, was synthesized. It exhibited separation abilities to disubstituted benzene isomers and some chiral solutes. It was also found that the polarity of CD derivatives can be lowered both by chemically bonding it to polysiloxane and by diluting it in polysiloxane. The separation abilities of the polysiloxane anchored CDs (SP CD) are higher than that of the unbonded CDs (S CD) and the diluted S CD at lower column temperature. Hydrosilylation reaction is one of the best methods to lower the operating temperature of CDs.

Hydrogen absorption of slurry system composed of different MgNi alloy and benzene

The hydrogen absorption amount and kinetics of the slurry formed by suspending the MgNi alloy powder in liquid benzene were studied. It is discovered that hydrogen is absorbed by both the solid phase(alloy) and liquid phase(C 6H 6) and the hydrogen absorption rate varies with the temperature and the content of the Mg-Ni in the slurry. Most hydrogen absorption curves of the slurry fall into two regions, in which the mechanism of hydriding reaction in the slurry system is different. In the former region, the hydriding of the alloy proceeds with hydrogen diffusing through C 6H 6. The part in the second region is the outcome of the hydrogenation of C 6H 6. At 548 K and under the hydrogen pressure of 4.5 MPa the saturation capacity for the slurry of 80% C 6H 6(mass fraction)+20% MgNi(mass fraction) is 5.9% (mass fraction) hydrogen, which is 97% of the theoretic capacity of the slurry system. The hydride of the alloy MgNi, which is only the hydride of Mg 2Ni phase, Mg 2NiH 4, is an efficient catalyst for the hydrogenation of C 6H 6 into C 6H 12(C 6H 6+3H 2→C 6H 12) in the slurry system.

PERVAPORATION FOR SEPARATING BENZENE/CYCLOHEXANE MIXTURE BY P(AA-MA) COPOLYMER MEMBRANES

P（AA-MA） copolymers composed of acrylic acid and methyl acrylate with different molecular weights and sequence structures were synthesized by combination of ATRP and selective hydrolysis. These copolymers were used as membrane materials to separate benzene/cyclohexane mixture by pervaporation. The effects of molecular weight and sequence structure of the copolymers on the pervaporation performance were investigated in detail. For the random copolymers, the permeate flux decreased rapidly with the increasing of molecular weight. The separation factor was also influenced by the molecular weight, which was changed from no selectivity to cyclohexane selectivity with increasing the molecular weight. Contrarily, the block copolymer membrane showed good benzene selectivity with separation factor of 4.3 and permeate flux of 157 g/（m2h） to 50 wt% benzene/cyclohexane mixture.

有机蒙脱石/壳聚糖气凝胶的制备及有机污染控制应用

以蒙脱石(Mnt)为主要原料,十六烷基三甲基溴化铵(C16)为疏水改性剂,壳聚糖(CS)为交联剂,通过超声法、溶胶凝胶法和冷冻干燥制得有机蒙脱石/壳聚糖气凝胶(CS-C16Mnt)。采用扫描电子显微镜(SEM)、X射线衍射(XRD)、傅里叶红外光谱(FT-IR)、比表面积及孔结构(BET)等手段对材料进行表征。结果表明,超声溶胀使C16Mnt片层扩张、叠层裂开,CS通过静电作用和氢键与C16Mnt结合,且CS-C16Mnt具有气凝胶典型的三维网络结构。吸附和吸收实验表明,CS-C16Mnt具有良好的有机污染控制能力。当C16Mnt与CS的质量比为10∶1、超声时间为10 min时,处理效果最好,在气相环境中对苯的吸附量达720.9 mg/g,在液相环境中对不同油和有机溶剂的吸收量为14.4~29.0 g/g。此外,CS-C16Mnt具有操作简便、易于回收等优势,是具有应用潜力的有机污染治理材料。

轴向配体对铁卟啉催化氧化环己烷和苯C—H键的影响

采用密度泛函理论方法系统研究了带有不同轴向配体(F^(-)、Cl^(-)、CH_(3)COO^(-)、SCH^(-)_(3))的铁卟啉作为仿生催化剂催化氧化环己烷和苯C—H键的反应,重点考察了轴向配体对高价铁-氧卟啉几何结构和电子结构的影响,以及轴向配体影响高价铁-氧卟啉氧化环己烷和苯C—H键反应活性的本质差异。相较于其他轴向配体,F^(-)作为轴向配体使高价铁-氧卟啉具有更高的活性,更易于氧化环己烷和苯的C—H键。与苯环C—H键氧化反应相比,改变轴向配体对环己烷C—H键氧化反应的活性影响更大,且轴向配体主要通过影响过渡态结构中环己烷的形变能来改变环己烷C—H键氧化反应的活化能。而在苯环C—H键氧化反应中,轴向配体主要影响过渡态结构中高价铁-氧卟啉与苯的相互作用能以及苯分子的形变能。

Ru/SiO_(2)催化NaBH_(4)还原苯制环己烷性能研究

通过浸渍原位还原法制备了Ru/SiO_(2)催化剂,考察了载体粒径和织构性质对Ru催化NaBH_(4)还原苯制环己烷性能的影响,并优化了反应条件。结果表明,NaBH_(4)还原苯制环己烷反应主要发生在催化剂的大孔和外表面上。不同粒径、不同用量SiO_(2)负载Ru催化NaBH_(4)产氢速率与它们催化NaBH_(4)还原苯制环己烷的收率趋势大致相同,说明苯是由NaBH_(4)在Ru上解离的活性氢还原的。当RuCl_(3)·3H_(2)O与SiO_(2)(50 nm)的物质的量之比为1∶12.8,RuCl_(3)·3H_(2)O、NaOH和NaBH_(4)的浓度分别为0.030 mol/L、0.053 mol/L和1.74 mol/L时,NaBH_(4)水解产生适宜的活性氢,还原RuCl_(3)·3H_(2)O生成适宜的金属Ru活性位,环己烷收率高达99.8%。

用于苯和环己烷分离的金属有机骨架研究进展

金属有机框架(MOFs)结合了亚微米尺度孔径可调和密闭空间孔隙化学的优点,通过合理的设计和功能化,在气体分子吸附分离中识别微小差异方面具有广阔的应用前景。探索了MOFs在苯和环己烷吸附分离方面的应用,并展望了MOFs分离系统的未来发展。

粗苯加氢工艺中芳烃苯系物的分离探讨

在如今有机化工领域快速发展的背景下,苯系物作为常用的有机化工原料,其加工处理工艺也在不断进步。文章针对芳烃苯系物的分离工艺现状进行了阐述,分析了传统工艺面临的问题与挑战。探讨了粗苯加氢工艺中芳烃苯系物分离的影响因素,并针对性对相关工艺要点及改进措施进行分析,希望能为相关从业者提供参考。

环己醇工业生产概述和展望

通过对环己醇工业生产发展情况进行总结,并重点追踪环己烯水合法生产工艺优化,分别就加氢工序、水合工序、精馏工序进行了总结,并针对生产工艺劣势提出了发展方向。

国外某高磷赤铁矿尾矿回收磷试验研究

为弥补国外某高磷赤铁矿矿石高价进口的部分成本损失,提高其综合利用率,本试验针对该高磷赤铁矿磁选尾矿中铁矿物和磷矿物进行选矿研究。在磁选尾矿性质基础上,确定水玻璃用量为750 g/t,玉米淀粉用量为300 g/t,十二烷基苯磺酸钠用量为69.72 g/t,经过1粗3精2扫浮选闭路试验,得到P_(2)O_(5)品位为31.08%、回收率为85.25%的磷灰石精矿,实现了尾矿废弃物的再利用。

氢气/环己烷分离用聚酰胺膜的制备

膜材料性能是膜分离技术工业化应用的关键。首先,以2,6,14三氨基三蝶烯和4,4苯甲酰氯为合成单体,通过直接缩合酰化反应,制备了网状三蝶烯基聚酰胺聚合物。然后,并以溶液涂覆法,制备了截留型微孔聚酰胺膜。采用膜法气体分离方法,研究氢气环己烷混合气体的筛分分离性能。采用傅里叶转换红外光谱仪(FT IR)、核磁氢谱(^(1)H NMR)、X线衍射(XRD)等表征手段证实了聚酰胺聚合物的合成。利用扫描电子显微镜(SEM)分析了复合膜表面完整性及厚度。最后考察了进料浓度、操作温度和流量等操作参数对复合膜筛分分离H_(2)/环己烷体系性能的影响规律。结果表明,高进料浓度及低操作温度可有效提高膜性能且由于聚合物膜网状结构的存在,分离膜仅需15 kPa的跨膜压差(跨膜驱动力),即可实现99%以上的截留率。网状三蝶烯基聚酰胺聚合物膜在氢气净化方面具有较好的应用前景。

环己烷-乙酸共沸体系的分离工艺研究

中国石油化工集团有限公司原创性地提出了环己烯酯化加氢制备环己酮新工艺,开发出了新一代环己酮生产技术,并正在中石化湖南石油化工有限公司建设全球最大的环己酮生产线。针对该技术中环己烷-乙酸共沸体系的分离问题,提出采用以水为共沸剂,利用环己烷与水共沸的特性,打破环己烷和乙酸之间的共沸体系,实现环己烷和乙酸的高效分离。结果表明:采用共沸精馏工艺和反应精馏-共沸集成工艺均可实现环己烷和乙酸的高效分离,环己烷中乙酸质量分数小于0.1%,乙酸纯度大于99.8%,均满足工艺要求,但是由于在反应精馏塔中引入水会造成水分下移至反应床层,造成环己烯转化率下降,因此在工业中宜采用共沸精馏工艺。

环己酮、环己醇制备技术进展

介绍了制备环己醇和环己酮两条工业化路线:(1)通过环己烷氧化制备环己醇和环己酮;(2)通过环己烯水合制备环己醇。还特别介绍了近年来环己烷氧化反应催化剂方面的进展,包括光氧化催化剂,纳米催化剂,Gif催化剂,仿生催化剂,沸石催化剂以及复合催化剂等。并探讨了环己醇和环己酮工业化制备技术将来研究的方向。

在Pd/γ-Al_2O_3催化剂上液相苯加氢的反应动力学

采用Pd/γ-Al2O3催化剂,在排除扩散影响的条件下,研究了液相苯催化加氢制环己烷的反应动力学。实验测定了反应温度、氢气压力、反应物浓度等因素对反应速率的影响,反应温度研究的范围为393～453K,氢气压力为1.1～3.8MPa。研究结果表明,液相苯加氢反应对苯表现为零级,对氢压表现为一级,反应活化能为43.88kJ/mol。运用该动力学模型对在较低苯浓度下进行的加氢反应进行了预测,预测值与实验值能较好地吻合。