不同微观结构脱硫胶粉的制备及其对改性沥青性能影响

本文探索了采用力化学和热化学脱硫制备不同微观形态脱硫胶粉的可行性，并研究了对改性沥青性能影响。结果表明，两种手段均可制备不同微观形态的脱硫胶粉。由于脱硫机理不同，两种方式制备的脱硫胶粉微观形态不同。随着反应温度升高，脱硫胶粉的交联密度及硫含量降低、氧含量增加，溶胶含量及PDI增加、M_n降低。脱硫胶粉改性沥青的加工和易性增强、高温性能及弹性降低，储存稳定性先变弱后增强，力化学脱硫胶粉改性沥青的低温性能先降低后升高，热化学脱硫胶粉改性沥青的低温性能降低。随着胶粉粒径变细，热化学脱硫胶粉的交联密度及硫含量降低，氧含量增加，溶胶含量及PDI增加，M_n降低，力化学脱硫胶粉的相反；力化学脱硫胶粉改性沥青的高低温性能及弹性增强，热化学脱硫胶粉改性沥青的相反；两种脱硫胶粉改性沥青的储存稳定性增强。     

车用燃料油氧化脱硫技术进展

概述了应用于车用燃料油的多种脱硫技术，主要包括加氢脱硫、催化裂化脱硫、吸附脱硫、萃取脱硫、生物脱硫等，并详细介绍了氧化脱硫技术及其脱硫机理。氧化脱硫技术主要包括：含硫化合物的氧化和分离两个步骤，从原子结构上来看，硫原子比碳原子多5个3d轨道，使得含硫化合物更容易接受氧原子而被氧化，通过氧化剂将有机硫化合物氧化成砜类，就能增加其极性，使其更容易溶于极性溶剂，从而达到与烃类分离的目的。与其他脱硫技术相比氧化脱硫技术的投资少，操作条件温和且不消耗氢气，对加氢脱硫难以脱除的二苯并噻吩(DBT)类化合物有较高的脱硫效率，能达到超深度脱硫的要求。     

柴油脱硫的机理研究以及反应中的溶剂效应

柴油的脱硫技术分为加氢脱硫和非加氢脱硫。在非加氢脱硫的研究中,氧化脱硫技术具有反应条件温和、不使用昂贵的氢气、投资和操作费用低等优点日益受到重视。文章介绍了柴油的脱硫技术的机理方面的研究进展。其中包括加氢脱硫的反应网络;以及氧化脱硫研究中,光化学氧化体系和有机过氧化物氧化体系中DBT的氧化机理。在不同的反应体系中,溶剂对含硫化合物的脱除也有很大的影响.     

燃油脱硫技术研究进展

综述了燃油脱硫技术的研究进展.介绍了燃油中硫含量的现状和国内外标准,重点阐述了脱硫工艺的开发和应用情况,列举了加氢脱硫、氧化脱硫、吸附脱硫等主要脱硫工艺的研究现状;并就燃油脱硫工艺技术的发展提出了建议.     

孝义煤电化学脱硫研究：Ⅰ.电解体系的研究

对孝义 不同电解体系中的脱硫率进行了考察。对不同电解氢气和不同助剂的影响进行了研究。发现ＮａＯＨ和Ｈ２ＳＯ４均是较好的脱硫体系，Ｃｌ＾－对电解脱硫有明显的促进作用，但对煤质的破坏程度很大。对煤的电解脱友规律的研究表明，碱性体系中的电解反应为包括脱硫反应的综合反应，对煤为一级，表观活化能为４１．８８ｋＪ／ｍｏｌ。     

吸附-微生物脱硫原位耦合工艺的吸附剂选择

吸附-生物原位耦合脱硫工艺是耦合了吸附脱硫的速率快和生物脱硫的选择性高的优点的新型油品脱硫工艺. 该耦合工艺通过在脱硫微生物表面组装脱硫吸附剂来实现. 比较了常用脱硫吸附剂γ-Al₂O₃、Na-Y分子筛和活性炭在与德氏假单胞杆菌R-8进行吸附-微生物催化原位耦合脱硫工艺中的应用效果. 其中, Na-Y分子筛抑制细胞的脱硫活性, 活性炭吸附了底物二苯并噻吩(DBT)之后难以解吸, 因此, 二者均不适用于耦合脱硫工艺. γ-Al₂O₃由于能够快速地从油相中吸附DBT, 然后将DBT解吸下来传递给R-8细菌进行生物降解, 加快了DBT的传质速率, 从而有效地提高了脱硫速率. 研究还发现纳米结构的γ-Al₂O₃与R-8耦合脱硫的效果优于普通尺寸的γ-Al₂O₃, 所以认为纳米γ-Al₂O₃是原位耦合脱硫较好的吸附剂选择.     

脱硫菌在自然界硫循环中的作用与意义

硫是生命必需的大量元素,硫循环失衡会造成生态的破坏。通过对硫循环、脱硫细菌的概念的阐述以及对生物脱硫作用机理的介绍,综合分析了脱硫菌脱除不同硫分的作用方式以及脱硫的不同途径,并初步探讨了其在自然界硫循环中的作用与意义。     

一种新型半干法烟气脱硫方法的机理分析

湿法烟气脱硫是目前效率最高、应用得最为广泛的一种烟气脱硫技术，因制浆设备庞大，占地面积大，管道设备易腐蚀、结垢，有废水污染和烟气再加热系统等，使其投资和运行费用均较高，使湿法脱硫在某些场合(如要求中等脱硫效率且费用低)的应用受到一定的限制。与湿法脱硫相比，干法烟气脱硫由于不需要喷水和再加热系统而成为一种简易的低成本脱硫方法，     

加氢脱硫催化剂与反应机理的研究进展

本文综述了加氢脱硫反应机理、加氢脱硫催化剂的研究与开发的最新进展.对常用的模型化合物的加氢脱硫机理及其影响因素、催化剂的结构、活性相与助剂、载体以及添加剂的性互作用与影响进行了讨论.     

溴化钠水溶液体系中煤的电化学脱硫

煤炭脱硫技术包括:物理洗选、化学脱硫、生物脱硫、超声波脱硫和微波脱硫等[1～3]。物理洗选法脱硫最经济,但只能脱无机硫。生物、化学法脱硫不仅能脱无机硫,也能脱有机硫,但生产成本昂贵,距工业应用尚有一定距离。20世纪80年代出现的电化学脱硫技术是一种既能克服物理、化学等法的缺点,又能达到较好脱硫效果的洁净、温和的脱硫方法[4,5]。本文对电化学氧化脱硫进行了研究,探讨了电化学氧化法脱除煤中硫的适宜体系和条件。1　实验部分1 1　原料和试剂　实验采用山西平朔煤(Pingsucoal)为原料,煤样粒径小于0 125mm。对煤样进行硫分析,其…     

Determination of PASHs by various analytical techniques based on gas chromatography-mass spectrometry: application to a biodesulfurization process

Polycyclic aromatic sulphur heterocyclic (PASH) compounds, such as dibenzothiophene (DBT) and alkylated derivatives are used as model compounds in biodesulfurization processes. The development of these processes is focused on the reduction of the concentration of sulphur in gasoline and gas–oil [D.J. Monticello, Curr. Opin. Biotechnol. 11 (2000) 540], in order to meet European Union and United States directives.

The evaluation of biodesulfurization processes requires the development of adequate analytical techniques, allowing the identification of any transformation products generated. The identification of intermediates and final products permits the evaluation of the degradation process.

In this work, seven sulfurated compounds and one non-sulfurated compound have been selected to develop an extraction method and to compare the sensitivity and identification capabilities of three different gas chromatography ionization modes. The selected compounds are: dibenzothiophene (DBT), 4-methyl-dibenzothiophene (4-m-DBT), 4,6-dimethyl-dibenzothiophene (4,6-dm-DBT) and 4,6 diethyl-dibenzothiophene (4,6 de-DBT), all of which can be used as model compounds in biodesulfurization processes; as well as dibenzothiophene sulfoxide (DBTO₂), dibenzothiophene sulfone (DBTO) and 2-(2-hydroxybiphenyl)-benzenesulfinate (HBPS), which are intermediate products in biodesulfurization processes of DBT [ A. Alcon, V.E. Santos, A.B. Martín, P. Yustos, F. García-Ochoa, Biochem. Eng. J. 26 (2005) 168]. Furthermore, a non-sulfurated compound, 2-hydroxybiphenyl (2-HBP), has also been selected as it is the final product in the biodesulfurization process of DBT [A. Alcon, V.E. Santos, A.B. Martín, P. Yustos, F. García-Ochoa. Biochem. Eng. J. 26 (2005) 168].

Since, typically, biodesulfurization reactions take place in a biphasic medium, two extraction methods have been developed: a liquid–liquid extraction method for the watery phase and a solid phase extraction method for the organic phase. Recoveries of the selected compound in both media were studied. They were in the range of 80–100% for the watery and in the range of 40–60% for the organic phase, respectively.

Gas chromatography coupled to mass spectrometry (GC–MS) has been employed for the identification of these selected compounds. Three different ionization modes were applied: conventional electron impact (EI); positive chemical ionization (PCI), using methane as the reagent gas; and a recently developed ionization mode known as hybrid chemical ionization (HCI), using perfluorotri-n-butylamine as the reagent gas. Limits of detection and identification capabilities have been compared between the three analytical techniques.

The sensitivity of the three analytical techniques was studied and LOD between 0.05 and 1, between 0.09 and 2 and between 0.001 and 0.043 were achieved for PCI, EI and HCI, respectively.

The developed method was applied in samples from a biodesulfurization process. The biodesulfurization reactions were conducted in resting cell operation mode, using Erlenmeyer flasks or an agitated tank bioreactor. The microorganism employed was Pseudomonas putida CECT 5279. The reaction was performed under controlled air flow, stirring and temperature conditions.     

Chromatographic methods applied in the monitoring of biodesulfurization processes - State of the art

Analytical methodologies employed in biodesulfurization processes have been reviewed; attention is primarily focused on the use of analytical techniques in the identification of degradation products and on the monitoring of degradation processes in which microbial sulphur-specific transformations take place. This is the first review of analytical techniques applied to biodesulfurization processes. Methodologies based on gas chromatography (GC) are the most frequently employed, in tandem with various detectors, mainly with the mass spectrometry (MS) detector, and the flame ionization detector (FID). High performance liquid chromatography (HPLC) coupled with ultra violet (UV) detection has also been widely employed. Different sulphurated compounds are used as model in biodesulphurization processes, naphtothiophene (NTH), benzothiophene (BTH), alkilated BTH, dibenzothiophene (DBT), alkilated DBT and their transformation products has been reviewed. DBT is the most frequently employed.     

Hydrodynamics of bioreactor systems for liquid-liquid contacting

Applied Biochemistry and Biotechnology - Two liquid-liquid bioreactors, a stirred-tank and a novel electrostatic-dispersion system, are being used to investigate biodesulfurization of oil by...     

Enhanced Dibenzothiophene Biodesulfurization by Immobilized Cells of Brevibacterium lutescens in n-Octane–Water Biphasic System

In this study, it was the first report that the Brevibacterium lutescens CCZU12-1 was employed as a sulfur removing bacteria. Using dibenzothiophene (DBT) as the sole sulfur source, B. lutescens could selectively degrade DBT into 2-hydroxybiphenyl (2-HBP) via the “4S” pathway. In the basal salt medium (BSM) supplemented with 0.25 mM DBT and 0.5 g/L Tween-80, high desulfurization rate (100 %) was obtained by growth cells after 60 h. Furthermore, the n-octane–water (10:90, v/v) biphasic system was built for the biodesulfurization by resting cells. Moreover, a combination of magnetic nano Fe₃O₄ particles with calcium alginate immobilization was used for enhancing biodesulfurization. In this n-octane–water biphasic system, immobilized B. lutescens cells could be reused for not less than four times. Therefore, B. lutescens CCZU12-1 shows high potential in the biodesulfurization.     

Influence of the Carbon Source on Gordonia alkanivorans Strain 1B Resistance to 2-Hydroxybiphenyl Toxicity

The viability of bacteria plays a critical role in the enhancement of fossil fuels biodesulfurization efficiency since cells are exposed to toxic compounds such as 2-hydroxybiphenyl (2-HBP), the end product of dibenzothiophene (DBT) biodesulfurization. The goal of this work was to study the influence of the carbon source on the resistance of Gordonia alkanivorans strain 1B to 2-HBP. The physiological response of this bacterium, pre-grown in glucose or fructose, to 2-HBP was evaluated using two approaches: a growth inhibition toxicity test and flow cytometry. The results obtained from the growth inhibition bioassays showed that the carbon source has an influence on the sensitivity of strain 1B growing cells to 2-HBP. The highest IC₅₀ value was obtained for the assay using fructose as carbon source in both inoculum growth and test medium (IC₅₀-48 h?=?0.464 mM). Relatively to the evaluation of 2-HBP effect on the physiological state of resting cells by flow cytometry, the results showed that concentrations of 2-HBP >1 mM generated significant loss of cell viability. The higher the 2-HBP concentration, the higher the toxicity effect on cells and the faster the loss of cell viability. In overall, the flow cytometry results highlighted that strain 1B resting cells grown in glucose-SO₄ or glucose-DBT are physiologically less resistant to 2-HBP than resting cells grown in fructose-SO₄ or fructose-DBT, respectively.     

Biodesulfurization of Model Compounds and De-asphalted Bunker Oil by Mixed Culture

In this study, complicated model sulfur compounds in bunker oil and de-asphalted bunker oil were biodesulfurized in a batch process by microbial consortium enriched from oil sludge. Dibenzothiophene (DBT) and benzo[b]naphtho[1,2-d]thiophene (BNT1) were selected as model sulfur compounds. The results show that the mixed culture was able to grow by utilizing DBT and BNT1 as the sole sulfur source, while the cell density was higher using DBT than BNT1 as the sulfur source. GC-MS analysis of their desulfurized metabolites indicates that both DBT and BNT1 could be desulfurized through the sulfur-specific degradation pathway with the selective cleavage of carbon–sulfur bonds. When DBT and BNT1 coexisted, the biodesulfurization efficiency of BNT1 decreased significantly as the DBT concentrations increased (>0.1 mmol/L). BNT1 desulfurization efficiency also decreased along with the increase of 2-hydroxybiphenyl as the end product of DBT desulfurization. For real bunker oil, only 2.8 % of sulfur was removed without de-asphalting after 7 days of biotreatment. After de-asphalting, the biodesulfurization efficiency was significantly improved (26.2–36.5 %), which is mainly attributed to fully mixing of the oil and water due to the decreased viscosity of bunker oil.     

Coal bioprocessing research at the institute of gas technology

Coal bioprocessing research at the Institute of Gas Technology (IGT) has included solubilization, gasification, desulfurization, denitrogenation, production of specialty chemicals, and the remediation of organic and inorganic wastes associated with coal utilization. Currently, research is focused on desulfurization and remediation. Desulfurization research concerns the development of processes to remove organic sulfur or to convert a portion of pyritic sulfur to sulfuric acid rapidly, thereby serving as a pretreatment to aid the thermochemical conversion of coal to coke and liquid products. The removal of as much as 91% organic sulfur from coal has been achieved, and biodesulfurization of coal has been confirmed by seven analytical techniques performed in six different laboratories. Recent studies have involved the use of molecular genetics to develop strains of bacteria with higher levels of desulfurization activity, and the development of methods for the preparation, storage, and utilization of biodesulfurization catalysts. Remediation studies include the development ofin situ and on-site technologies to treat soil contaminated with coal tar, the leaching of metals from fly ash, and the treatment of waste water resulting from fly ash leaching or from acidic mine drainage (AMD). IGT currently has two projects in EPA’s SITE program concerned with the remediation of coal tar-contaminated soil, and other related technologies are being developed. Efficient laboratory-scale processes for the removal of metals from fly ash and from soil so that the solids pass EPA’s TCLP test, and the subsequent treatment of the leachates or AMD to meet all regulatory requirements have been developed. Data obtained in these projects are presented in particular, and a general discussion of the application of biotechnology to coal is offered.     

Selection of adsorbents for <Emphasis Type="Italic">in-situ</Emphasis> coupling technology of adsorptive desulfurization and biodesulfurization

In-situ coupling of adsorptive desulfurization and biodesulfurization is a new desulfurization technology for fossil oil. It has the merits of high-selectivity of biodesulfurization and high-rate of adsorptive desulfurization. It is carried out by assembling nano-adsorbents onto surfaces of microbial cells. In this work, In-situ coupling desulfurization technology of widely used desulfurization adsorbents of γ-Al₂O₃, Na-Y molecular sieves, and active carbon with Pseudomonas delafieldii R-8 were studied. Results show that Na-Y molecular sieves restrain the activity of R-8 cells and active carbon cannot desorb the substrate dibenzothiophene (DBT). Thus, they are not applicable to in-situ coupling desulfurization technology. Gamma-Al₂O₃ can adsorb DBT from oil phase quickly, and then desorb it and transfer it to R-8 cells for biodegradation, thus increasing desulfurization rate. It is also found that nano-sized γ-Al₂O₃ increases desulfurization rate more than regular-sized γ-Al₂O₃. Therefore, nano-γ-Al₂O₃ is regarded as the better adsorbent for this in-situ coupling desulfurization technology. Supported by National Basic Research Program of China (Grant No: 2006CB202507) and National High-tech R&D Program (Grant No: 2006AA02Z209)     

Enhancement of Dibenzothiophene Desulfurization by Gordonia alkanivorans Strain 1B Using Sugar Beet Molasses as Alternative Carbon Source

There are several problems limiting an industrial application of fossil fuel biodesulfurization, and one of them is the cost of culture media used to grow the microorganisms involved in the process. In this context, the utilization of alternative carbon sources resulting from agro-industrial by-products could be a strategy to reduce the investment in the operating expenses of a future industrial application. Recently, Gordonia alkanivorans 1B was described as a fructophilic desulfurizing bacterium, and this characteristic opens a new interest in alternative carbon sources rich in fructose. Thus, the goal of this study was to evaluate the utilization of sugar beet molasses (SBM) in the dibenzothiophene (DBT) desulfurization process using strain 1B. SBM firstly treated with 0.25 % BaCl₂ (w/v) was used after sucrose acidic hydrolysis or in a simultaneous saccharification and fermentation process with a Zygosaccharomyces bailii Talf1 invertase (1 %), showing promising results. In optimal conditions, strain 1B presented a μ _max of 0.0795 h^?1, and all DBT was converted to 2-hydroxybiphenyl (250 μM) within 48 h with a maximum production rate of 7.78 μM h^?1. Our results showed the high potential of SBM to be used in a future industrial fossil fuel biodesulfurization process using strain 1B.     

Biodesulfurization of a System Containing Synthetic Fuel Using Rhodococcus erythropolis ATCC 4277

The burning of fossil fuels has released a large quantity of pollutants into the atmosphere. In this context, sulfur dioxide is one of the most noxious gas which, on reacting with moist air, is transformed into sulfuric acid, causing the acid rain. In response, many countries have reformulated their legislation in order to enforce the commercialization of fuels with very low sulfur levels. The existing desulfurization processes cannot remove such low levels of sulfur and thus a biodesulfurization has been developed, where the degradation of sulfur occurs through the action of microorganisms. Rhodococcus erythropolis has been identified as one of the most promising bacteria for use in the biodesulfurization. In this study, the effectiveness of the strain R. erythropolis ATCC 4277 in the desulfurization of dibenzothiophene (DBT) was evaluated in a batch reactor using an organic phase (n-dodecane or diesel) concentrations of 20, 80, and 100 % (v/v). This strain was able to degrade 93.3, 98.0, and 95.5 % of the DBT in the presence of 20, 80, and 100 % (v/v) of dodecane, respectively. The highest value for the specific DBT degradation rate was 44?mmol DBT?·?kg DCW^?1?·?h^?1, attained in the reactor containing 80 % (v/v) of n-dodecane as the organic phase.