硫化氢对负载型钴铈双金属吸附剂脱除模拟煤气中单质汞的促进机理

采用共沉淀法制备了一系列不同配比的钴铈双金属吸附剂（Ce_xCo_yTi）,在固定床实验台上探究低温（80～240℃）下脱除模拟煤气中Hg⁰的特性及机理。结果表明,Ce、Co负载比为0.2、0.1时,在120℃、N₂+H₂S气氛下吸附剂表现出最佳的脱汞效果,其效率为95.3%;Ce_0.2Co_0.1Ti在N₂气氛下不仅存在物理吸附而且存在较强的化学吸附;在考察范围内,Ce_0.2Co_0.1Ti脱汞效率随H₂S浓度的增加而增加。采用基于DFT的第一性原理软件VASP模拟H₂S和Hg在Ce_0.2Co_0.1Ti表面的吸附及反应过程,表明Hg化学吸附于吸附剂表面,H₂S易解离形成S,且S极易与吸附态的Hg反应生成HgS,活化能垒为0.214eV,反应遵循Langmuir-Hinshelwood机理。     

A study on sulphidation and regeneration of Z-Sorb III sorbent for H2S removal from simulated ELCOGAS IGCC syngas

The sulphidation and regeneration of the sorbent Z-Sorb III has been investigated at bench scale in a high-temperature, high-pressure fixed-bed unit, over a range of conditions relevant to the Puertollano IGCC plant (Spain). The effect of gas hourly space velocity (1000-), temperature (673-773 K) and pressure (1-2 MPa) on sulphidation is studied. As predicted by thermodynamics, the sorbent is capable of reducing the H₂S concentration from 10,000 ppmv to near 0 ppmv. The analysis of the experimental results shows that gas residence time has a strong effect on sorbent utilization. Below , the sorbent seems to promote the Boudouard reaction. As a result of this, CO content in the gas stream increases with simultaneous carbon formation in the solid phase. At higher gas velocities , CO disproportionation does not occur and the sulphidation reaction proceeds isothermally to complete conversion of ZnO. Further increase in space velocity to leads to lower sorbent utilization, which is typical of diffusion-limited gas-solid heterogeneous reactions. On the other hand, sulphidation temperature has very little effect on sulphur loading uptake which is slightly higher at 773 K than at 673 K. Regarding the effect of pressure, the sorbent is most effective at 2 MPa, almost reaching the theoretical saturation capacity. The study of the durability of the sorbent is investigated through multiple sulphidation-regeneration cycles. Oxidative dry mild regeneration using an oxygen concentration of 2% v/v results in complete regeneration of the sulphided sorbent without severe structural property changes or activity loss. The primary reaction during regeneration of the sulphided sorbent is direct oxidation of the metal sulphide with SO₂ release.     

Research into the kinetics of COS elimination from syngas at moderate temperatures

Thermogravimetry at constant temperature and programmed temperatures is used to study reaction kinetics and possible mechanism of COS desulfurization using ferric oxide as the main active component. The apparent reaction activation energy is smaller in hydrogen atmosphere than in nitrogen. The desulfurization reaction of COS takes place easily in a hydrogen atmosphere. At the same time, the influence of the reducing temperature on the desulfurizing reaction was also studied in the TGA apparatus and was shown to play an important part for ferric desulfurization. The optimum temperature for the reducing reaction is under 360 °C. The kinetics of the COS removal reaction are approximately first-order. When the reaction gas contains hydrogen, the apparent reaction activation energy is 12.36 kJ mol⁻¹, in contrast to 21.92 kJ mol⁻¹ in the absence of hydrogen.     

Sawdust: A green and economical sorbent for thallium removal

Removal/preconcentration of thallium(I) ions from aqueous solution by sawdust; a waste material derived from the commercial processing of Cedrus Deodar wood for furniture production was investigated. A simple and low-cost modification results in increasing the sorption capacity of raw sawdust from 2.71 to 13.18 mg g⁻¹. Sorption was found to be rapid (98% within 8 min). The binding of metal ions was found to be pH dependent, optimal sorption accruing at around pH 6–9. Potentiometeric titrations of sawdust revealed two distinct pK_a values, the first having the value similar to carboxylic groups (3.3–4.8) and second comparable with that of amines (8.53–10.2) with the surface site densities of 1.99 × 10⁻⁴ and 7.94 × 10⁻⁵ mol g⁻¹, respectively. Retained Tl(I) ions were eluted with 5 ml 0.1 mol l⁻¹ HCl. Detection limit of 0.0125 μg ml⁻¹ was achieved with an enrichment factor of 160. Recovery was quantitative using sample volume of 800 ml. The Langmuir, Freundlich and D–R isotherm equations were used to describe partitioning behavior for the system at different temperatures. Kinetic and thermodynamic behavior of sawdust for Tl(I) ions removal was also studied.     

煤基吸附剂脱除燃煤电厂烟气中汞的研究进展

燃煤电厂产生的烟气是汞排放的主要来源之一。概述了目前电厂烟气中汞污染情况和主要脱汞方法,介绍了煤基吸附剂在汞污染控制中的应用。煤基吸附剂应用于烟气脱汞时其吸附活性与多种因素有关,总结了烟气中SO2,CO2,CO,HCl等成分对活性炭吸附剂脱汞性能的影响,讨论了不同吸附温度和炭汞比例下活性炭的吸附效率,分析了不同改性方法对活性炭脱汞效率的影响机理。针对活性炭脱汞成本较高的问题,介绍了飞灰吸附剂的脱汞性能及吸附温度和入口汞含量对其的影响。此外,褐煤活性焦成本低廉,具有丰富的比表面积和孔径结构,化学活性高,吸附性能好,是一种很有前景的电厂烟气脱汞用吸附剂。     

A brown coal-based sorbent for water treatment for removal of humic substances: Optimization of the sorbent manufacturing process

A two-factor mathematical model has been proposed for the preparation of a lignite sorbent designed for the removal of humic substances from water purification. It has been shown that this model adequately describes the dependence of the sorption capacity of the sorbent on the preparation conditions, the temperature and time of the heat treatment process. Based on the proposed model, optimal conditions for the manufacture of the lignite sorbent that ensures the maximum extraction of humic substances from water. By means of the experimental-statistical analysis method, the dependence of the sorption capacity of the polydisperse sorbent on the particle size was found. It has been shown that these models can effectively predict the properties of a brown coal sorbent.     

Development of a pilot-scale acid gas removal system for coal syngas

The Korean pilot-scale gasification facility consists of a coal gasifier, hot gas filtering system, and acid gas removal (AGR) system. The syngas stream from the coal gasification at the rate of 100–120 Nm³/hr included pollutants such as fly ash, H₂S, COS, etc. The acid gas, such as H₂S and COS, is removed in the AGR system before generating electricity by gas engine and producing chemicals like Di-methyl Ether (DME) in the catalytic reactor. A hydrolysis system was installed to hydrolyze COS into H₂S. The designed operation temperature and pressure of the COS hydrolysis system are 150 °C and 8 kg/cm². After the hydrolysis system, COS was reduced below 1 ppm at the normal operating condition. The normal designed operation temperature and pressure of the AGR system are below 40 °C and 8 kg/cm². Fe-chelate was used as an absorbent. H₂S was removed below 0.5 ppm in the AGR system when the maximum concentration of H₂S was 900 ppm. A small scale COS adsorber was also installed and tested to remove COS below 0.5 ppm. COS was removed below 0.1 ppm after the COS adsorbents such as the activated carbon and ion exchange resin. This work was presented at the 6 ^th Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006.     

高炉煤气中羰基硫水解吸附催化剂的制备及性能研究

以移动床活性焦烟气净化工艺运转中产生的磨损废活性焦（EAC）为原料制备羰基硫（COS）水解吸附材料,结合XRD、TG、BET、TPD、FTIR、SEM、XPS手段对EAC进行表征,发现磨损废焦具有发达的表面孔道结构与丰富的表面官能团,比表面积达445.38 m²/g。研究不同碱量改性及工艺参数对COS催化水解脱除效率的影响,结果表明在100℃下,负载0.450%NaOH时EAC催化剂活性最强,穿透硫容达126.58 mg/g。对反应后样品进行分析表明COS在废焦中主要以S存在,这种固硫方式增大了硫容量,为废焦的梯级利用与硫资源化提供了一条新途径。     

NHD溶剂脱除合成气中COS气体的讨论

近年来,NHD脱硫、脱碳技术已得到广泛应用,不仅应用于合成氨原料气的脱硫及变换气的脱碳,还逐渐向其他领域扩展.如甲醇生产过程中原料气的脱硫、脱碳,羰基合成所需CO气体中酸性气的脱除等.在上述原料气体中,均含有一定量的COS气体.由于制气原料、制气方法及预处理工艺不同,其COS含量也不相同.合成反应要求将合成气中总硫脱除到0.1×10-6以下,以保护催化剂,一般通过干法精脱硫工艺来实现,也可以在NHD脱碳的同时,脱除COS.     

New sorbent hydrogels for removal of acidic dyes and metal ions from aqueous solutions

Summary Poly(N-hydroxymethylacrylamide), PHMA, hydrogels were prepared by using N-hydroxymethylacrylamide, HMA, monomer and polyethyleneglycol(400)diacrylate as a crosslinking agent in aqueous medium and then amine groups were incorporated onto PHMA hydrogels by amination reaction with different diamines. The obtained hydrogels were characterized by determination of amine value, hydroxymethyl group content and FTIR spectra. The amine value of hydrogels changed from 2.23 to 4.64 mmol/g by depending on the amine compounds used in amination reaction. Their swelling degree increased at acidic pH values and they showed pH dependent swelling behaviour. They were used as sorbent for removal of indigo carmine and Cu(II) ion, as a model dye molecule and metal ion, respectively, from aqueous solutions. The adsorption properties of the hydrogels were investigated by depending on pH, time and initial indigo carmine or Cu(II) ion concentration. It was seen that the amine group incorporated hydrogels have quite high adsorption rate and adsorption capacity, and their adsorption capacities changed with pH of the solution. Langmuir isotherm model was the best fit for adsorption of both indigo carmine and Cu (II) ion.     

Numerical solution of the model for sulphur dioxide removal in a fluidized bed of sorbent

The model is represented by a set of nonlinear, variable-coefficient partial differential equations of the parabolic type. Approximating the time derivative with backward differences leads to a semi-implicit scheme, which was solved by the iteration procedure with a variable time step. The character of the solved set necessitates the use of an extremely small increment of time. In order to make the computations feasible, the method of pseudo-steady states was employed. The pseudo-steady states are detected as an approximate balance of large forces which bring about the motion of the solution in the phase space.     

NT705型脱硫剂的本征动力学研究

用热重法研究了还原后的NT70 5型脱硫剂脱除合成气中H2 S的脱硫反应本征动力学。在很强的还原氛围中 ,4 0 0℃的条件下 ,脱硫剂中的Fe2 O3 被还原为Fe3 O4,并进一步还原为FeO ,最终还原为单质Fe。实验采用 10 0 12 0目的小颗粒 ,在 2 80 4 0 0℃范围内 ,原料气H2 S质量浓度为 0 995 5 2 g/m3 的条件下进行。实验数据用未反应收缩核模型处理 ,结果表明 ,小颗粒脱硫剂的脱硫反应速率为化学反应控制 ,脱硫反应为一级反应     

制备方法对MnO_x-TiO_2吸附剂脱汞性能的影响

针对燃煤烟气中单质汞不溶于水,难以脱除的问题,采用水热合成法(HT)和沉积-沉淀法(DP)制备了Mn Ox-Ti O2单质汞(Hg0)吸附剂,在固定床实验台架上考察2种吸附剂(Mn Ti-HT和Mn Ti-DP)的脱汞性能;利用N2吸附/脱附、透射电子显微镜(TEM)、X射线衍射(XRD)、H2程序升温还原(H2-TPR)和X射线光电子能谱(XPS)等技术对吸附剂进行物化表征。结果表明:物理吸附不是吸附剂脱汞的主要因素。Mn Ti-DP对Hg0的吸附剂量为620μg/g,远高于Mn Ti-HT的236μg/g,说明制备方法对吸附剂的脱汞性能有较大影响。Mn Ti-DP吸附剂中Mn含量较高,Mn4+含量约为34%,远高于Mn Ti-HT的Mn4+(22%);Mn Ti-DP中化学吸附态氧和晶格氧的强度均高于MnTi-HT,表明Mn Ti-DP中化学吸附态氧的总体含量高于Mn Ti-HT,有利于增强Mn Ti-DP还原特性,提高脱汞能力。     

常温碘甲烷吸附剂的研制及其动力学研究

制备了一种常温脱碘剂,在固定床反应器中研究了该脱碘剂与碘甲烷气体的床层反应动力学,并在此基础上推导出了床层动力学方程。研究结果发现,实验值与计算值十分吻合,可用于实际计算。     

用于合成气制高值产物的InZrOx 氧化物制备及性能

以四水合硝酸铟和五水合硝酸锆为原料，通过共沉淀法和水热法制备InZrOx氧化物，并在最佳制备条件下探究煅烧温度对合成氧化物的影响，与SAPO-34分子筛结合为双功能催化剂用于用于合成气催化转化制高值产物。采用XRD、SEM-EDS、HRTEM、XPS和BET对氧化物的织构性质、晶体结构、形貌特征及表面电荷进行表征与测试，并在固定床反应器中系统研究了空速、原料气氢碳比（物质的量）、氧化物与分子筛质量比、反应温度及反应压力对催化效果的影响规律。结果表明，共沉淀法得到的氧化物在各方面表现均优于水热法，最佳煅烧温度为550 ℃。在空速为2000 mL/(gcat·h)、原料气氢碳比（物质的量）为3：1、m(InZrOx)：m(SAPO-34)=1：1、400 ℃、3 MPa的反应条件下，CO转化率为67.58%，高值产物选择性为70.81%[C2-4=选择性为37.74%、液体燃料（C5+）烃类选择性为33.07%]，C2-4=收率可达23.98%，副产物CO2选择性仅为5.99%。     

石灰石和氧化钙脱除H2S和COS动力学研究

向煤气化炉中喷入石灰石或氧化钙粉是脱除煤气中含硫化合物最简便的方法之一。文中采用热重分析仪在常压(绝压为0.1 MPa)下对石灰石和氧化钙分别脱除H2S和COS的反应进行了动力学研究。实验条件为:温度1 025—1 450 K、H2S和COS的分压范围0.000 3—0.001 5 MPa、颗粒粒径为0.84—1.0 mm。结果表明,石灰石和氧化钙与H2S和COS的反应均表现为一级反应;与CaCO脱除H2S和COS的反应相比,CaO3脱除H2S和COS反应的初速率几乎快10倍。在0.105—1.0 mm粒径范围内的实验表明,CaO脱除H2S和COS的反应与颗粒粒度成反比关系。     

煤与KOH共热解制备富氢合成气的研究

以制备富氢合成气为目的,进行了煤与KOH共热解试验。试验在升温速率6％／min,120mL／minN2气氛下进行,采用GC—TCD测定合成气的组成,考察了碱煤比对释氢特性、合成气组成与转化率的影响。结果表明,在不同的碱煤比下,合成气中H2始终占据优势,碱煤比为2：1时,氢气产量与转化效率达到最优。     

HSA immobilized novel polymeric matrix as an alternative sorbent in hemoperfusion columns for bilirubin removal

HSA immobilized poly(2-hydroxyethylmethacrylate), HSA-P[HEMA], cryogel monolith was examined as an alternative sorbent to be used in hemoperfusion columns for bilirubin removal from serum. The cryogel monolith synthesis was performed by free radical polymerization using MBAA as crosslinker, APS and TEMED as redox pair. Cyanogen bromide (CNBr) was used as a matrix-activating agent for the preparation of immobilized cryogels. Control cryogel monolith, P[HEMA], and HSA-P[HEMA] were characterized by swelling test, SEM images, porosity and surface area measurements, and blood compatibility tests. Activation and immobilization processes were optimized. The removal of bilirubin from plasma samples overloaded with bilirubin was performed using P[HEMA] cryogel monoliths containing different amounts of immobilized HSA in continuous mode. Several factors affecting adsorption capacity of the matrix such as incubation time, HSA concentration, bilirubin concentration in plasma and temperature were analysed. The maximum bilirubin removal from plasma was 25.4 mg/g at 37.5 °C. The desorption agent was 0.1 M NaOH and 1.0 M NaCl containing solution. The reusability was tested for 10 consecutive adsorption–desorption cycles. The adsorption isotherm models and kinetics of process were also studied.     

合成气膜分离脱碳经济性分析

合成气作为生产尿素、氨、精细化学品及各种油品的重要原料,其中的二氧化碳必须脱除至符合合成反应的工艺要求。分析了常规的吸附法脱碳工艺的优缺点,以及气体膜分离技术的应用现状,认为二氧化碳膜分离技术在合成气脱碳领域具有较好前景。针对煤制合成气合成甲醇的气源条件及分离指标,采用固定载体膜组件在模试装置上对合成气二氧化碳的分离性能进行了系统的测试与考察,采用PRO/Ⅱ软件对合成气脱碳二级膜过程的分离指标、能耗和处理成本进行了详细的分析。结果表明:二级膜过程能实现合成气制甲醇净化气中二氧化碳摩尔分数小于3%的要求,同时有效成分损失低于3%,在此条件下合成气处理费用为1 m~3产品气0.04~0.06美元;合成气价格对不同分离指标的气体处理费用有较大影响,且当有效组分损失大时影响更显著。     

燃煤电厂吸附剂喷射脱汞技术的研究进展

燃煤汞污染已引起广泛关注。燃煤电厂控制汞排放最成熟可行的技术是烟道活性炭喷射技术,但该技术在我国燃煤电厂的广泛应用还存在较多的科学问题,因为活性炭对烟气汞的脱除是包含吸附、扩散、传质及化学反应在内的多元化过程,因此,针对燃煤电厂吸附剂喷射脱汞技术的研究已成为当前的热点课题。本文从吸附剂喷射脱汞技术原理、脱汞吸附剂的评价方法、汞吸附机理研究以及吸附剂喷射脱汞数学模型方面评述了燃煤电厂吸附剂喷射脱汞技术近些年取得的研究进展,并在此基础上提出了开发廉价高效、可再生的脱汞吸附剂,全面深入研究吸附剂的脱汞机理以及开发简单、精确的吸附剂喷射脱汞数学模型等后续研究方向,可为我国燃煤电厂吸附剂喷射脱汞技术的开发提供一定指导。