Desulfurization of diesel oils by a newly isolated dibenzothiophene-degrading Nocardia sp. strain CYKS2

A dibenzothiophene (DBT)-degrading bacterial strain was isolated from dyeing industry wastewater and identified as Nocardia sp. CYKS2. The newly isolated bacterial strain Nocardia sp. CYKS2 was able to convert DBT to 2-hydroxybiphenyl (2-HBP) as the dead-end metabolite through a sulfur-specific pathway. Other organic sulfur compounds, such as thiophene derivatives, thiazole derivatives, sulfides, and disulfides were also desulfurized by Nocardia sp. CYKS2. In batch culture, 0.2 mM DBT was completely desulfurized in 60 h. After DBT was depleted, neither cell growth nor 2-HBP production was observed. When a model oil which DBT was dissolved in hexadecane was treated with growing cells, DBT was desulfurized from 10 mM to about 2 mM in 80 h. In this case, desulfurization rate was 0.279 mg-sulfur/(L-dispersion.h), which was about 2.5 times higher than that in the previous case of batch culture. When diesel oil was treated, the sulfur content decreased from 0.3 to 0.24 wt % in 48 h. A volumetric phase ratio of oil to water was 1/10 in this case. The sulfur decreased from 0.3 to 0.2 wt % in 48 h, when the volumetric phase ratio was 1/20. The desulfurization rates were 0.909 and 0.992 mg-sulfur/(L-dispersion.h), respectively.     

Molecular mechanisms of biocatalytic desulfurization of fossil fuels

The development of biocatalytic desulfurization of petroleum fractions may allow its use in place of conventional hydrodesulfurization (HDS). Dibenzothiophene (DBT) is representative of a broad range of sulfur heterocycles found in petroleum that are recalcitrant to desulfurization via HDS. Rhodococcus sp. strain IGTS8 has the ability to convert DBT to 2-hydroxybiphenyl (HBP) with the release of inorganic sulfur. The conversion of DBT to HBP is catalyzed by a multienzyme pathway consisting of two monooxygenases and a desulfinase. The final reaction catalyzed by the desulfinase appears to be the rate limiting step in the pathway. Each of the enzymes has been purified to homogeneity and their kinetic and physical properties studied. Neither monooxygenase has a tightly bound cofactor and each requires an NADH-FMN oxidoreductase for activity. An NADH-FMN oxidoreductase has been purified from Rhodococcus and is a protein of approximately 25,000 molecular weight with no apparent sequence homology to any other protein in the databases. We describe a unique sulfur acquisition system that Rhodococcus uses to obtain sulfur from very stable heterocyclic molecules.     

Biocatalytic sulfur removal from fuels: applicability for producing low sulfur gasoline

Environmental regulations are driving R&D efforts to produce low sulfur fuels, including diesel fuel and gasoline for motor vehicles. Biocatalytic sulfur removal from fuels has potential applicability for producing low sulfur gasoline. Microbial biocatalysts have been identified that can biotransform sulfur compounds found in fuels, including ones that selectively remove sulfur from dibenzothiophene heterocyclic compounds. Most attention is give to the 4S pathway of Rhodococcus, which can remove sulfur from substituted and unsubstituted dibenzothiophenes, including sulfur compounds that hinder chemical catalysis and that resist removal by mild hydrotreatment. Various bioreactor and bioprocess designs are being tested for use with biocatalysts, including recombinant biocatalysts, for use in removing sulfur from fuels and feedstocks within the petroleum refinery stream. With bioprocess improvements that enhance biocatalyst stability, achieve faster kinetics, improve mass transfer limitations, temperature and solvent tolerance, as well as broaden substrate specificity to attack a greater range of heterocyclic compounds, biocatalysis may be a cost-effective approach to achieve the production of low sulfur gasoline. The challenge will be to accomplish these improvements by the time the regulations for low sulfur gasoline and other vehicle fuels go into effect in order to be competitive with emerging nonbiological desulfurization technologies.     

Biodegradation of variable-chain-length alkanes at low temperatures by a psychrotrophic Rhodococcus sp

The psychorotrophic Rhodococcus sp. strain Q15 was examined for its ability to degrade individual n-alkanes and diesel fuel at low temperatures, and its alkane catabolic pathway was investigated by biochemical and genetic techniques. At 0 and 5 degrees C, Q15 mineralized the short-chain alkanes dodecane and hexadecane to a greater extent than that observed for the long-chain alkanes octacosane and dotriacontane. Q15 utilized a broad range of aliphatics (C10 to C21 alkanes, branched alkanes, and a substituted cyclohexane) present in diesel fuel at 5 degrees C. Mineralization of hexadecane at 5 degrees C was significantly greater in both hydrocarbon-contaminated and pristine soil microcosms seeded with Q15 cells than in uninoculated control soil microcosms. The detection of hexadecane and dodecane metabolic intermediates (1-hexadecanol and 2-hexadecanol and 1-dodecanol and 2-dodecanone, respectively) by solid-phase microextraction-gas chromatography-mass spectrometry and the utilization of potential metabolic intermediates indicated that Q15 oxidizes alkanes by both the terminal oxidation pathway and the subterminal oxidation pathway. Genetic characterization by PCR and nucleotide sequence analysis indicated that Q15 possesses an aliphatic aldehyde dehydrogenase gene highly homologous to the Rhodococcus erythropolis the A gene. Rhodococcus sp. strain Q15 possessed two large plasmids of approximately 90 and 115 kb (shown to mediate Cd resistance) which were not required for alkane mineralization, although the 90-kb plasmid enhanced mineralization of some alkanes and growth on diesel oil at both 5 and 25 degrees C.     

KR脱硫渣的综合利用现状及其氧化去硫研究进展

KR脱硫的渣资源化利用有利于促进钢铁企业的绿色化发展.KR脱硫渣中主要成分为CaO,且含有质量分数为1.0％～2.5％的硫,直接将K R脱硫渣回用于冶炼工艺会导致钢液增硫.若能将渣中的硫脱出,可有效促进KR脱硫渣在钢铁冶炼工艺的资源化利用.因此,针对当前KR脱硫渣综合利用存在的问题,总结分析有关CaS氧化过程的热力学和...     

川东北高含硫天然气中有机硫化合物的分析方法研究

基于脉冲火焰光度检测器(PFPD)对硫化合物具有高的灵敏度和选择性以及价格低廉等优点,采用硫化氢选择性吸收法和气相色谱-脉冲火焰光度法(GC-PFPD)相结合技术,对川东北高含硫天然气中有机硫化合物的形态分布进行了分析。优化了天然气预处理工艺条件,采用惰性的预处理系统除去高含硫天然气中的硫化氢,收集剩余的有机硫气体,用GC-PFPD法进行分析检测,根据标准物质保留时间定性方法和外标定量方法进行了定性和定量研究。结果表明:在最佳的实验条件下,该方法能充分除去高含硫天然气中硫化氢,且操作简单,对同一样品重复测定5次,各组分的相对标准偏差(RSD)都在10%以内,方法的加标回收率在91%~104%之间。     

Simultaneous refining of phosphorus and sulfur from hot metal utilizing recycled sinter ore dust

An experimental study is carried out to determine the possibility of utilizing the recycled sinter ore dust for refinging flux for hot metal. The dust has good physical and chemical properties as an injection powder, however, it contains masses of about 0.24% S and a substantial amount of sulfur which can be picked up by the hot metal during the injection treatment. Therefore, sinter ore dust is mixed with burnt lime, fluorspar and sodium carbonate to increase the sulfide capacity of the flux. The fluxes are tested for hot metal dephosphorization and desulfurization in laboratory and plant scale experiments. The fluxes show an excellent dephosphorization efficiency without sulfur pick up. In case of the flux containing sodium carbonate masses of 10%, sulfur in hot metal is simultaneously removed. In addition, a higher manganese yield in hot metal is obtained in case of a sodium carbonate containing flux at the end of injection treatment.     

冷却速率对KR脱硫渣中硫析出行为的影响

KR脱硫渣中主要成分(CaO)为转炉冶炼的优质造渣原料,通过氧化性气氛将渣中硫脱除后可将其用于转炉冶炼.但由于炉渣冷却制度不同,渣中硫的析出行为和赋存状态会发生变化,对炉渣氧化脱硫效果产生影响.基于此,以合成渣的形式探究冷速对KR脱硫渣中硫析出行为的影响,旨在明确KR脱硫渣中硫赋存状态及析出行为与冷却速率的关系,为后续...     

Smelting Oxidation Desulfurization of Copper Slags

 According to the mechanism of sulfur removal easily through oxidation, the process of smelting oxidation desulfurization of copper slags is studied, which supplies a new thinking for obtaining the molten iron of lower sulfur content by smelting reduction of copper slags. Special attention is given to the effects of the holding temperature, the holding time and CaF2, CaO addition amounts on the desulfurization rate of copper slags. The results indicate that the rate of copper slags smelting oxidation desulfurization depends on the matte mass transfer rate through the slag phase. After the oxidation treatment, sulfur of copper slags can be removed as SO2 efficiently. Amount of Ca2+ of copper slags affects the desulfurization rate greatly, and the slag desulfurization rate is reduced by adding a certain amount of CaF2 and CaO. Compared with CaF2, CaO is negative to slags sulfur removal with equal Ca2+ addition. Under the air flow of 0. 3 L/min, the sulfur content of copper slags can be reduced to 0. 00467% in the condition of the holding time of 3 min and the holding temperature of 1500 ℃. The sulfur content of molten iron is reduced to 0. 0008% in the smelting reduction of treated slags, and the problem of high sulfur content of molten iron obtained by smelting reduction with copper slag has been successively solved.     

高炉煤气精脱硫技术的半工业试验

 高炉煤气中有机硫(主要是COS)含量高,无机硫含量低,硫的脱除难度大。针对以上特点,在山东某金属公司进行了干法精脱硫工艺的半工业试验。具体的工艺方案为,脱硫设备布置在高炉TRT设备之后,高炉煤气通过旁通管从高炉煤气管网上接入脱硫试验装置。水解和脱硫反应器均为填充床形式,采用“一级水解+脱硫”串联“二级水解+脱硫”的两级串联设计方案。在相应的水解和脱硫反应器中分别填充一种改进型的Al₂O₃基低温水解催化剂和氧化铁基脱硫剂。水解催化剂促使煤气中的有机硫(COS)与水蒸气反应生成H₂S,再由脱硫剂与H₂S反应生成Fe₂S₃,从而实现煤气中硫的脱除。在半工业试验中,进入脱硫设备的煤气流量为400 m3/h,煤气温度为80~100 ℃,COS的体积分数约为70%,H₂S的体积分数约为25%,煤气中硫浓度为145 mg/m3。经过300 h的连续试验,结果表明,该脱硫工艺全过程废水零排放;高炉煤气中有机硫(COS)转化为无机硫(H₂S)的转化率约为99%;煤气中硫分的脱除率大于96%;能够保证煤气燃烧后烟气中SO₂浓度小于10 mg/m3。     

Desulfurization and deoxidation of Cu-S-O alloy in induction melting and solidification under argon and their rates of elimination in vacuum induction melting

Solid Cu-S-O alloy (about 150 g) containing 0.05 pct S and 0.04 pct O (by weight) was heated to 1473 or 1573 K under argon at 6.5 to 101 kPa. Desulfurization of 64 to 80 pct and deoxidation of 75 to 82 pct were observed. The extent did not depend on argon pressure, and this desulfurization and deoxidation probably occurred during melting. In the course of solidification and remelting of molten Cu-S-O alloys containing sulfur and oxygen at approximately the same concentration,i.e., 0.027 pct S and 0.026 pct O, and 0.0456 pct S and 0.0416 pct O under argon at 1.33 to 102 kPa, the percentage of sulfur removed was 49 to 75, the percentage of oxygen removed was 63 to 81, and the extent did not depend on argon pressure. The alloys containing more oxygen than sulfur before cooling,i.e., 0.0216 pct S and 0.081 pct O and 0.0185 pct S and 0.15 pct O, 73 to 90 pct of the sulfur was eliminated. Most desulfurization and deoxidation probably occurred in the course of solidification, because vigorous boiling was observed at this stage. The rates of removal of oxygen and sulfur from molten Cu-S-O alloys maintained at 1373, 1473, and 1573 K under vacuum were expressed by a first-order rate equation, and the dependence of their rate constants on the reciprocal of temperature was determined. In alloys in which pct S ≃pct O before evacuation and pct S ranges from 0.0202 to 0.042 and pct O ranges from 0.023 to 0.048, 79 to 96 pct desulfurization and 66 to 87 pct deoxidation were observed. For the alloys with pct O > pct S initially,i.e., 0.081 pct O and 0.0216 pct S, and 0.15 pct O and 0.0176 pct S, 85 to 94 pct desulfurization was observed and was close to the observed levels of desulfurization in solidification and remelting of the alloys with pct O > pct S under argon.     

A glutathione S-transferase with activity towards cis-1, 2-dichloroepoxyethane is involved in isoprene utilization by Rhodococcus sp. strain AD45

Rhodococcus sp. strain AD45 was isolated from an enrichment culture on isoprene (2-methyl-1,3-butadiene). Isoprene-grown cells of strain AD45 oxidized isoprene to 3,4-epoxy-3-methyl-1-butene, cis-1, 2-dichloroethene to cis-1,2-dichloroepoxyethane, and trans-1, 2-dichloroethene to trans-1,2-dichloroepoxyethane. Isoprene-grown cells also degraded cis-1,2-dichloroepoxyethane and trans-1, 2-dichloroepoxyethane. All organic chlorine was liberated as chloride during degradation of cis-1,2-dichloroepoxyethane. A glutathione (GSH)-dependent activity towards 3, 4-epoxy-3-methyl-1-butene, epoxypropane, cis-1,2-dichloroepoxyethane, and trans-1,2-dichloroepoxyethane was detected in cell extracts of cultures grown on isoprene and 3,4-epoxy-3-methyl-1-butene. The epoxide-degrading activity of strain AD45 was irreversibly lost upon incubation of cells with 1,2-epoxyhexane. A conjugate of GSH and 1, 2-epoxyhexane was detected in cell extracts of cells exposed to 1, 2-epoxyhexane, indicating that GSH is the physiological cofactor of the epoxide-transforming activity. The results indicate that a GSH S-transferase is involved in the metabolism of isoprene and that the enzyme can detoxify reactive epoxides produced by monooxygenation of chlorinated ethenes.     

KR脱硫渣高温矿物组成及含硫相的析出行为

 KR脱硫渣是KR铁水预处理脱硫工艺的副产品,其磁选后尾渣中CaO质量分数大于50%。可将其用作优质造渣原料返回到转炉炼钢工艺中,降低转炉炼钢的原料消耗。但KR脱硫渣中的硫(w((S))=1.0%～2.5%)成为转炉冶炼循环利用的障碍,直接将其用于转炉冶炼会使钢中的硫含量增加。因此,根据工业KR脱硫渣的化学成分,以合成渣的形式对KR脱硫渣中矿物组成及含硫相的析出行为进行研究,旨在明确KR脱硫渣中各矿物相组成及炉渣中硫的析出行为和赋存状态,为后续通过氧化性气氛有效脱除KR脱硫渣中的硫提供理论参考。采用热力学数据库FactSage 8.0的Equilib模块对CaO-SiO₂-CaS-CaF₂基熔渣的凝固过程进行模拟,利用XRD、SEM-EDS对合成渣样品的矿物组成及微观形貌进行分析、检测。热力学计算结果表明,CaS的析晶温度为1 320 ℃,低于MeO#1相、MeO#2相及2CaO·SiO₂相的析晶温度。炉渣样品的面扫描分析结果表明,在实际凝固过程中,受残余液相黏度增大的影响炉渣中少量硫未能析出形成CaS晶体,则以非晶态的形式赋存在基质相中。KR脱硫渣主要由C₃S相、MeO#1相(CaO固溶体)、MeO#2相(MgO固溶体)、基质相和CaS相等矿物组成。炉渣中的硫主要以游离态CaS晶体形式赋存,少量以非晶态硫的形式赋存。炉渣中CaS晶粒主要沿着先析出的高熔点硅酸盐(C₃S)相边界析出。     

碘量-重量法测定脱硫灰还原产物中硫化钙和亚硫酸钙

准确测定硫化钙和亚硫酸钙的含量,对于脱硫灰还原工艺的参数选择和转化进程的研究具有重要意义。用过量碘标准滴定溶液将样品中的硫化钙和亚硫酸钙氧化,磷酸(1+4)溶液溶解样品并调节pH值,硫代硫酸钠标准滴定溶液返滴定得到硫化钙和亚硫酸钙消耗的碘标准滴定溶液的量,从而得到硫化钙和亚硫酸钙的总含量;硫化钙与碘反应生成硫单质,用热氢氧化钾溶液洗脱生成的硫单质的质量得到样品中硫化钙的含量,两者之差即为亚硫酸钙的含量,从而建立了脱硫灰还原产物中硫化钙和亚硫酸钙的测定方法。将实验方法应用于不同工艺流程得到的脱硫灰还原产物测定,7次平行测定硫化钙和亚硫酸钙结果的相对标准偏差(RSD,n=7)为0.54%~1.8%。按照实验方法,对3种配制的脱硫灰还原产物中硫化钙和亚硫酸钙进行测定,测定值均和理论值相符。     

碘量-重量法测定脱硫灰还原产物中硫化钙和亚硫酸钙

准确测定硫化钙和亚硫酸钙的含量,对于脱硫灰还原工艺的参数选择和转化进程的研究具有重要意义。用过量碘标准滴定溶液将样品中的硫化钙和亚硫酸钙氧化,磷酸(1+4)溶液溶解样品并调节pH值,硫代硫酸钠标准滴定溶液返滴定得到硫化钙和亚硫酸钙消耗的碘标准滴定溶液的量,从而得到硫化钙和亚硫酸钙的总含量;硫化钙与碘反应生成硫单质,用热氢氧化钾溶液洗脱生成的硫单质的质量得到样品中硫化钙的含量,两者之差即为亚硫酸钙的含量,从而建立了脱硫灰还原产物中硫化钙和亚硫酸钙的测定方法。将实验方法应用于不同工艺流程得到的脱硫灰还原产物测定,7次平行测定硫化钙和亚硫酸钙结果的相对标准偏差(RSD,n=7)为0.54%~1.8%。按照实验方法,对3种配制的脱硫灰还原产物中硫化钙和亚硫酸钙进行测定,测定值均和理论值相符。     

The oxidation of liquid Ni3S2

Using a levitation technique, molten nickel sulfide droplets were oxidized at temperatures above 1500°C under oxygen potentials varying from 5 to 40 pct in He gas. To analyze the results, the oxidation process was divided into two stages. The first stage corresponded to the desulfurization of Ni₃S₂ by oxidation of the dissolved sulfur. In the second stage, a small amount of desulfurization, oxidation of nickel vapor and absorption of oxygen gas into the droplet occurred. Both stages were found to be controlled by mass transfer of oxygen within the gas boundary layer. Under conditions of high oxygen potential, a halo appeared around the levitated droplet during the initial period. This halo disappeared during desulfurization, but reappeared towards the end of the oxidation period. Formerly Post-Doctoral Fellow, Department of Metallurgy and Materials Science, University of Toronto.     

电渣重熔工艺对高氮钢脱硫的影响

对电渣重熔制备高氮钢的脱硫过程进行了研究,分别采用不同渣系和熔炼速率对高氮钢进行制备。对电渣重熔前后夹杂物进行电镜及成分分析,分析结果表明:硫化物夹杂的平均直径和单位面积数量大大减少,夹杂物的主要类型为MnS+Al2O3复合型夹杂物;适度提高渣中CaO含量可提高硫分配比,是提高脱硫效率的有效手段。同时,实验结果表明重熔速率对电渣重熔中的脱硫率具有重要影响。通过脱硫动力学推导,发现重熔速率越低,脱硫效果越明显,但实验发现脱硫率随重熔速率的降低有时呈现先降低后升高的趋势,其原因在于渣池中发生硫化物富集,导致"回硫"现象发生,降低了脱硫率。     

Effect of Fe_2O_3 Addition in MgO-CaO Refractory on Desulfurization of Liquid Iron

Forsteelmaking ,thematerialscontactingliquidsteelmaybehelpfulforsteelpurifying .Forexam ple ,thetundishcoverisakindofinsulatingmateri als ,whichcanreducetheheatlossofliquidsteelandprotectliquidsteelfromair .Withthedemandforhighpuritysteel,theacidmaterialsfortundishcov erarenolongeracceptableandreplacedbybasicma terialscontainingMgOandCaO[1,2 ] .Refractoriesarethematerialscontactingliquidsteelmainly ,butlittleattentionwaspaidtotheroleofrefractoriesforpurifyingliquidsteel.Inthepast ,thelifeofr…     

Removal of Sulfur from CaF2 Containing Desulfurization Slag Exhausted from Secondary Steelmaking Process by Oxidation

The oxidation behavior of sulfur in desulfurization slag generated from the secondary steelmaking process with air has been investigated in the temperature range of 973?K to 1373?K (700?°C to 1100?°C). Although a high removal rate of sulfur is not achieved at temperatures lower than 1273?K (1000?°C) because of the formation of CaSO₄, most of the sulfur is rapidly removed from slag as SO₂ gas in the 1273?K to 1373?K (700?°C to 1100?°C) range. This finding indicates that the desulfurization slag generated from the secondary steelmaking process can be reused as a desulfurized flux through air oxidation, making it possible to reduce significantly the amount of desulfurization slag for disposal.