Sulfur removal from hydrotreated petroleum fractions using ultrasound-assisted oxidative desulfurization process

Ultrasound-assisted oxidative desulfurization (UAOD) process was applied to diesel oil and petroleum product feedstock containing model sulfur compounds (benzothiophene, dibenzothiophene and dimethyldibenzothiophene). The influence of oxidant amount, volume of solvent for the extraction step and time and temperature of ultrasound treatment (20 kHz, 750 W, operating at 40%) was investigated. Using the optimized conditions for UAOD, sulfur removal up to 99% was achieved for model compounds in petroleum product feedstock using a molar proportion for H₂O₂:acetic acid:sulfur of 64:300:1, after 9 min of ultrasound treatment at 90 °C, followed by extraction with methanol (optimized solvent and oil ratio of 0.36). Using the same reagent amount and 9 min of ultrasound the removal of sulfur was higher than 75% for diesel oil samples. Sulfur removal without ultrasound using the same conditions was lower than 82% for model compounds and 55% for diesel oil samples showing that ultrasound improved the efficiency of oxidative desulfurization. In comparison to conventional hydrodesulfurization, the proposed UAOD process can be performed under relatively mild conditions (atmospheric pressure and 90 °C, without using metallic catalysts).     

FCC汽油萃取脱硫过程萃取剂筛选

分别考察了4种萃取剂在单一或复配条件下,对3种模拟汽油中单一含硫化合物及FCC汽油70～160 ℃切割馏分的萃取脱硫效果,效果皆佳的萃取剂为环丁砜。考察了操作温度、剂油比、环丁砜和四甘醇复配对脱硫率的影响。结果表明：温度对萃取脱硫率的影响较小。适宜的萃取条件为温度35 ℃,剂油比3∶1。环丁砜单一溶剂萃取脱硫效果较优。     

Removal of sulfur compounds from utility pipelined synthetic natural gas using modified activated carbons

Synthetic natural gas (SNG), which is produced from petroleum and distributed via pipeline in Honolulu by The Gas Company, was analyzed using a gas chromatograph equipped with a sulfur chemiluminescence detector (GC/SCD). Hydrogen sulfide (H₂S), methyl mercaptan (MM), ethyl mercaptan (EM), dimethylsulfide (DMS), dimethyl disulfide (DMDS), tetrahydrothiophene (THT), ethyl disulfide (EDS), and one unidentified compound (UN1) were detected. Among these sulfur compounds, THT is added as an odorant and was present in the highest concentration.A commercial activated carbon (Calgon OLC plus 12X30) was modified by oxidation and impregnation methods and the resulting materials were evaluated for their ability to adsorb sulfur compounds present in SNG. The evaluation results indicate that all of the modification methods can improve the retention of individual sulfur compounds or the total sulfur capacity compared with the untreated virgin carbon. It is also found that activated carbons impregnated with metal impurities have different selectivity for sulfur compounds. Cu and Zn loaded carbons had the highest capacity for H₂S removal, Fe loaded carbon was more efficient for DMS removal (the most difficult S compound to remove), and carbon oxidized by HNO₃ was the best for THT removal.Based on these findings, a composite sorbent consisting of Cu loaded and Fe loaded carbons was designed and tested. The test results indicate that the composite sorbent had improved performance in the removal of individual sulfur compound. A linear programming model was used to design a composite sorbent optimized to minimize the required sorbent mass based on a 1-kW scale fuel cell system service target. Validation tests showed that the optimized sorbent required less of the individual modified carbon components than when they were individually used for the same sulfur removal target.     

Sulfur removal of gas oil using ultrasound-assisted catalytic oxidative process and study of its optimum conditions

Ultrasound-assisted oxidative desulfurization process (UAOD) was applied to reduce sulfur compounds of gas oil containing various types of sulfur content. The environmental regulation requires a very deep desulfurization to eliminate the sulfur compounds. UAOD is a promising technology with lower operating cost and higher safety and environmental protection. For the first time the typical phase transfer agent (tetraoctyl-ammonium-bromide) was replaced with isobutanol because using isobutanol is much more economical than TOAB, imposing no contamination. The reaction was carried out at optimal point with various temperatures, in single-, two- and three step-procedures, investigating the effect of gradual increase of H₂O₂ and TOAB being used instead of isobutanol. Total sulfur concentration in oil phase was analyzed by ASTM-D3120 method. The highest removal of about 90% for gas oil containing 9,500 mg/kg of sulfur was achieved in three-steps during 17 minutes of process at 62±2 °C when 180.3 mmol of H₂O₂ was used and extraction carried out by methanol.     

Extraction conditions for removal of oxidized sulfur compounds in gas oil

An experimental study was conducted to investigate the extraction of oxidized sulfur compounds from gas oil. Solvents used for this purpose included acetone, acetonitrile, methanol and propanol. The effect of solvent concentration, solvent to gas oil ratio, temperature, time and number of stages was studied. To select the best solvent and conditions for extraction, two criteria were considered: high desulfurization and more hydrocarbon recovery. Results showed that extraction time and temperature have no significant effect. Methanol for low ability of extraction of oxidized sulfur compounds and propanol for low hydrocarbon recovery were excluded from further experiments. After the tests, the optimum conditions for extraction were determined to be 85% acetone, solvent/feed ratio of 1, two stages extraction in ambient temperature and enough time for mixing. In this condition 85% of sulfur compounds of gas oil containing 1,670 ppmw S were separated and 95% of gas oil was recovered.     

Coal hydrogenation: Quality of start-up solvents and partially process-derived recycle solvents

The performance of three sets of start-up solvents and one set of partially process-derived recycle solvents was studied in small autoclave coal hydrogenation tests. The start-up solvents were obtained by catalytically hydrotreating anthracene oils or creosote oils. It is shown that this preparation procedure converts polynuclear aromatics and two-ring aromatics to hydroaromatics and, ultimately, to alicyclics. Coal conversions using start-up solvents are found to reach a maximum at intermediate degrees of solvent hydrogenation which is believed to correspond to a maximal abundance of hydroaromatic solvent hydrogen donors. A solvent hydrogen donor index (SHDI), simply derived from ¹H n.m.r. spectral data, was devised and is found to successfully correlate coal conversions obtained using different start-up solvents, especially where N₂ gas rather than H₂ gas is employed in the autoclave tests. A set of partially process-derived recycle solvents were produced in multiple cycle continuous coal hydrogenation experiments. These were tested under relatively severe hydrogenation conditions in the presence of hydrogen gas, using the small autoclave unit. Substantial donation of solvent hydrogen was found to occur and coal conversions to hexane — and toluene-soluble products are found to be a smooth function of the solvent hydrogen donor index. It is concluded that the hydrogen donor capacity of a solvent is a major factor governing coal conversion, especially when the demand for solvent hydrogen is high. The SHDI parameter is useful in rationalizing the behaviour of start-up solvents. Also, at least in the first few cycles of a continuous two stage coal hydrogenation process, the SHDI parameter allows solvent quality to be monitored, and consequently optimized.     

Comparative studies on the effects of casting solvent on physico‐chemical and gas transport properties of dense polysulfone membrane used for CO2/CH4 separation

The effects of casting solvents on the physico–chemical and transport properties of polysulfone membranes were investigated. Comparative analysis of the properties of membranes prepared from a new solvent (diethylene glycol dimethyether, DEG) and other commonly used solvents (1‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, dimethyl sulfoxide and N,N‐dimethylformamide) were performed using gas permeation, X‐ray diffraction, scanning electron microscopy, thermogravimetric, and Fourier transform infrared spectroscopy analyses. The degree of polymer–solvent interaction was evaluated using the solvent molar volume, and Hansen and Flory–Huggins parameters. Membrane prepared from DEG displayed a relatively higher permeability of 29.08 barrer and CO₂/CH₄ selectivity of 23.12 compared to membranes prepared from other solvents. This improved performance was attributed to the better interaction between the DEG solvent and polysulfone than other solvents that were considered. DEG has the highest molar volume of 142.280 cm³/mol and the lowest Flory–Huggins parameter of 0.129. Thus a thorough evaluation of polymer–solvent interaction is very crucial in preparing membranes with optimum performance. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42205.     

固定床无碱脱硫技术在液化气脱硫中的应用

由于原料油繁杂,厂里生产的民用液化气中有机硫含量较高。装置原采用醇胺溶剂脱除大部分H2S后再采用碱洗、水洗工艺,有机硫难脱除,液化气个别质量指标如铜片腐蚀不稳定,经常不合格;同时碱渣的处理也较困难。通过对原液化气脱硫工艺进行改进,采用液化气固定床无碱脱硫工艺及相关催化剂、脱硫剂,液化气中总硫含量由脱前的237.1mg/m^3降为脱后的104.4mg/m^3左右,主要是降低有机硫,总硫脱除率达到≥50%,液化气铜片腐蚀100%合格。     

On the integration of CO2 capture with coal-fired power plants: A methodology to assess and optimise solvent-based post-combustion capture systems

Amine and other liquid solvent CO₂ capture systems capture have historically been developed in the oil and gas industry with a different emphasis to that expected for fossil fuel power generation with post-combustion capture. These types of units are now being adapted for combustion flue gas scrubbing for which they need to be designed to operate at lower CO₂ removal rates - around 85-90% and to be integrated with CO₂ compression systems. They also need to be operated as part of a complete power plant with the overall objective of turning fuel into low-carbon electricity.The performance optimisation approach for solvents being considered for post-combustion capture in power generation therefore needs to be updated to take into account integration with the power cycle and the compression train. The most appropriate metric for solvent assessment is the overall penalty on electricity output, rather than simply the thermal energy of regeneration of the solvent used.Methodologies to evaluate solvent performance that have been reported in the literature are first reviewed. The results of the model of a steam power cycle integrated with the compression system focusing on key parameters of the post-combustion capture plant - solvent energy of regeneration, solvent regeneration temperature and desorber pressure - are then presented. The model includes a rigorous thermodynamic integration of the heat available in the capture and compression units into the power cycle for a range of different solvents, and shows that the electricity output penalty of steam extraction has a strong dependence on solvent thermal stability and the temperature available for heat recovery. A method is provided for assessing the overall electricity output penalty (EOP), expressed as total kWh of lost output per tonne of CO₂ captured including ancillary power and compression, for likely combinations of these three key post-combustion process parameters. This correlation provides a more representative method for comparing post-combustion capture technology options than the use of single parameters such as solvent heat of regeneration.     

Immobilized fenton‐like ionic liquid: Catalytic performance for oxidative desulfurization

MCM‐41‐supported Fenton‐like ionic liquid catalysts were synthesized by the grafting method and applied in the removal of sulfur compounds in model oil. The structure and property of the catalysts were characterized by Fourier transform infrared spectra, X‐ray diffraction, diffuse reflectance spectra, transmission electron microscopy, thermogravimetric and differential scanning calorimetry, and N₂ adsorption‐desorption. Results suggested that Fenton‐like ionic liquid was supported on mesoporous material MCM‐41. Different desulfurization systems were studied. The results indicated that at room‐temperature (30°C) for 1 h, MCM‐41‐supported Fenton‐like ionic liquid in extraction combined with catalytic oxidative desulfurization (ECODS) system showed a high catalytic activity with H₂O₂ as the oxidant, and [Omim]BF₄ as the extractant. Different factors, such as temperature, the amount of H₂O₂, solvent, and different sulfur‐containing compounds for sulfur removal were investigated. Through the gas chromatography‐mass spectrometer (GC‐MS) analysis, dibenzothoiphene sulfone was proved to be the only product of dibenzothiophene oxidizing reaction. Furthermore, the process of ECODS was confirmed by GC‐MS results. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4696–4704, 2013     

基于分子管理的脱有机硫复配型溶剂的开发与应用

基于分子管理理念, 对脱有机硫复配型溶剂进行组成设计。采用两维溶解度参数理论, 筛选出与甲硫醇溶解度参数接近的溶剂作为复配溶剂中提高甲硫醇脱除率的组分;并根据胺的碱性、空间位阻效应对其与COS反应速率的影响规律, 选择具有较小空间位阻效应和适当强度碱性的环状胺类作为提高COS脱除率的溶剂组分。根据原料气的有机硫分布特点, 将所筛选的溶剂组分按一定比例配入N-甲基二乙醇胺(MDEA)中, 获得了两种复配溶剂(UDS-I, UDS-II)。脱硫实验结果表明, 对于COS占有机硫总量94%的天然气, UDS-I溶剂的COS脱除率较MDEA高出近44个百分点, 其净化天然气质量满足一类气的指标要求;对于甲硫醇占有机硫总量79%的焦化液化气, UDS-II溶剂的甲硫醇脱除率较MDEA高出近50个百分点, 其净化液化气的总硫含量满足民用液化气指标要求。     

Intensification of Mass Transfer in the Extraction Process with a Nanofluid Prepared in a Natural Deep Eutectic Solvent

The phytotoxic residues after olive oil production and residue leaves after pruning contain valuable bioactive compounds. A natural deep eutectic solvent (NADES) and an ethanol-water mixture were used for polyphenol extraction from olive pomace and leaves. Type of solvent, extraction temperature, and particle size of the leaves were optimized. NADES demonstrated better efficiency in the extraction process than conventional solvents; with higher temperature and smaller fraction of olive leaves, a higher yield of polyphenols was obtained from leaves. Extraction with a nanofluid as solvent was carried out. A stable nanofluid was prepared from NADES by adding Al₂O₃ nanoparticles. A higher yield was obtained with nanofluid from leaves, while an improvement of polyphenol extraction was achieved after the removal of oil from olive pomace.     

Effect of solvent on molecular composition in coal liquefaction

The product from uncatalysed liquefaction of lignite using synthesis gas (CO-Steam process) was examined by column chromatography, high-resolution mass spectrometry, gas chromatography-mass spectrometry, and low-voltage mass spectrometry. The nature of the vehicle solvent affected the type and distribution of compounds in the product oil. Anthracene oil and recycle oil as solvents gave mainly aromatics and phenols. When tetralin was used as solvent, the product showed larger amounts of oxygen compounds, more hydroaromatic compounds, and a greater degree of alkylation in high-molecular-weight aromatics. Tetralin, therefore, appears to be a more powerful hydrogen donor than anthracene oil or recycle oil in stabilizing intermediate fragments that would otherwise repolymerize. Carbon-number analysis data for liquids prepared using three different solvents are presented.     

Biofiltration control of pulping odors – hydrogen sulfide: performance,macrokinetics and coexistence effects of organo‐sulfur species

The work reported here describes the aerobic biodegradation of reduced sulfur compound mixtures in air streams by biofilters. Rates of removal of hydrogen sulfide as a sole substrate and in the presence of organo‐sulfur compounds were determined to see if there were any inhibitory effects of the organo‐sulfur compounds on the rate of hydrogen sulfide removal. Experiments were conducted in three bench‐scale biofilters packed with the mixtures of compost/perlite (4:1), hog fuel/ perlite (4:1), and compost/hog fuel/perlite (2:2:1), respectively. Hydrogen sulfide, the predominant odorous gas produced from kraft pulping processes, was used as the main pollutant (substrate). Other organo‐sulfur species (dimethyl sulfide and dimethyl disulfide), also emitted from kraft pulp mills, were used as competing (secondary) substrates in the waste gas stream. To describe rates of removal a Michaelis–Menten type kinetic equation was modified to incorporate the plug flow behavior of biofilters, and used in evaluating the pseudo‐kinetic parameters, V_max (the maximum removal rate) and K_m (the half saturation concentration), for hydrogen sulfide biodegradation, and the type of macrokinetic competition between hydrogen sulfide and the organo‐sulfur compounds. No significant differences in V _max for the three biofilters were observed. The V _max ranged between 136 and 147 g m⁻³ h ⁻¹, while the K_m varied from 44 to 59 ppmv for the three biofilters. Hydrogen sulfide elimination capacity was not affected by the presence of any of the organo‐sulfur species in all of the three biofilters, confirming earlier results that hydrogen sulfide removal in biofilters is independent of the presence of organo‐sulfur compounds mainly because of its easy biodegradability. © 1999 Society of Chemical Industry     

COMPUTATIONAL CHEMISTRY IN LIQUID EXTRACTION OF SULFUR COMPOUNDS FROM GASOLINE

Quantum and molecular mechanics methods were used to guide the development of a liquid extraction process for the removal of sulfur compounds from gasoline using an aqueous solvent containing n-butylamine (NBA). The calculational results suggest that the extraction mechanism was via forming micelles of NBA around single sulfur compounds. That is, micelles containing 6 to 192 molecules of NBA yielded negative formation energies. With increasing NBA amounts over the same range, total sulfur removal increased in extraction experiments. However, not all sulfur compounds were extracted simultaneously. Extraction selectivities were correlated to calculated formation energies between individual sulfur compounds and a single molecule of NBA. This suggests that extraction selectivity depended on attraction of each sulfur compound out of the gasoline to the NBA micelle wall. To provide sufficient extraction time, the number of extraction stages was investigated. The results predicted that about 10 theoretical stages would be required to achieve equal extractions of all sulfur compound types and 99⁺% total sulfur removal.     

Deep desulfurization of model oil by photocatalytic air oxidation and adsorption using Ti<Subscript>(1−<Emphasis Type="Italic">x</Emphasis>)</Subscript>M<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>2</Subscript> (M=Zr,Ce)

Deep desulfurization of model oil by photocatalytic air oxidation and adsorption using Ti_(1?x)M _x O₂ (M=Zr, Ce) was investigated. Ti_(1?x)M _x O₂ (M=Zr, Ce) was prepared by urea gelation/co-precipitation method, and characterized by N₂ adsorption, XRD and UV-vis spectra. UV irradiation greatly enhanced the adsorptive capacity and selectivity of TiO₂-ZrO₂ for organosulfur in model oil because organosulfur compounds were first photocatalytically oxidized to sulfoxides and sulfones over TiO₂-ZrO₂, which were then selectively adsorbed on the bifunctional material due to much higher polarities of generated sulfoxides and sulfones. The Ti/Zr molar ratio and calcination temperature were optimized to 5 : 5 and 500 °C with the sulfur removal of 99.6% after reaction for 2 h under UV irradiation. After adding 25 wt% toluene into model oil, the sulfur removal could still reach 97.2% after reaction for 7 h. TiO₂-ZrO₂ could be well regenrated by washing with acetonitrile followed by thermal treatment in air.     

Two-step adsorption process for deep desulfurization of diesel oil

An integrated adsorption process for deep desulfurization of diesel fuel was proposed and examined. Conventionally hydrodesulfurized straight run gas oil (HDS-SRGO) having less than 50 ppm sulfur was also adsorptively treated with activated carbon fiber (ACF) to attain the ultra low sulfur gas oil having less than 10 ppm sulfur. The ACF, used in cleaning-up HDS-SRGO, was successively examined in straight run gas oil (SRGO) treatment to enhance its hydrodesulfurization (HDS) reactivity over conventional CoMo catalyst by removing the nitrogen and refractory sulfur species contained in SRGO. Such integrated adsorption–reaction process makes it possible to utilize the maximum adsorption capacity of ACF and achieve ultra deep desulfurization og SRGO. Regeneration of used ACF with a conventional solvent was proved very effective in restoring its adsorption capacity.     

SOLUBILITY OF CO2AND H2S IN A MIXED SOLVENT

Mixed solvents are a combination of chemical and physical solvents and have some advantages over traditional treating solvents for the removal of acid gases from gas streams. The solubility of H₂S and CO₂in a mixed solvent consisting of AMP (2-amino-2-methyl-l-propanol), sulfolane, and water has been measured at 40 and 100°C at partial pressures of the acid gas to 6000 kPa. The solubility in the mixed solvent was compared with the solubility in an aqueous solution of equivalent amine concentration. At solution loadings less than 1 mol acid gas/mol amine, the solubility of the acid gas is lower in the mixed solvent than in the corresponding amine solvent. At higher loadings, the trend is reversed and the solubility is greater in the mixed solvent. The results are rationalized in terms of the effect of the physical solvent component on the chemical reaction and physical vapor-liquid equilibria. The solubility model of Deshmukh and Mather was used to correlate the data.     

Solvent Influence on the Hydrodeoxygenation of Guaiacol over Pt/SiO2 and Pt/H‐MFI 90 Catalysts

Second generation biofuels are produced in the bioliq® process at the Karlsruhe Institute of Technology via gasification of pyrolysis oil and synthesis of gasoline from the emerging synthesis gas. An alternative strategy is the direct upgrading of the pyrolysis oil by hydrodeoxygenation (HDO). The present study reports on the HDO of guaiacol as one of the phenolic compounds strongly abundant in such mixtures. Special focus was laid on the solvent influence using Pt‐based catalysts. Higher HDO ability was seen using nonpolar solvents and acidic supports. Characterization of the catalysts before and after the test showed that the solvent did not only influence the reactivity, but also the catalyst stability.     

Deep desulfurization of full range and low boiling diesel streams from Kuwait Lower Fars heavy crude

Information on feed quality and, in particular, various types of sulfur compounds present in the diesel (gas oil) fractions produced form different crudes and their HDS reactivities under different operating conditions are of a great value for the optimization and economics of the deep HDS process. This paper deals with deep desulfurization of gas oils obtained from a new heavy Kuwaiti crude, namely, Lower Fars (LF) which will be processed in the future at Kuwaiti refineries. Comparative studies were carried out to examine the extent of deep HDS, and the quality of diesel product using two gas oil feeds with different boiling ranges. The results revealed that the full range diesel feed stream produced from the LF crude was very difficult to desulfurize due to its low quality caused by high aromatics content (low feed saturation) together with the presence of high concentrations of organic nitrogen compounds and sterically hindered alkyl DBTs. The low-boiling range gas oil showed better desulfurization compared with the full range gas oil, however, deep desulfurization to 50 ppm sulfur was not achieved even at a temperature as high as 380 °C for both feeds. The desulfurized diesel product from the low-boiling gas-oil feed was better in quality with respect to the S, N and PNA contents and cetane index than the full-range gas-oil feed.