Chemical desulfurization of petroleum fractions for ultra-low sulfur fuels

An improved desulfurization process for removing sulfur from hydro treated diesel oil based on the oxidation of thiophenic type sulfur-containing compounds with H₂O₂ and acetic acid (AcOH) using H₂SO₄ as catalyst has been studied. The experimental results show that the sulfone content in the oxidation product increased rapidly with an increase in acetic acid and sulfuric acid ratios from 1:0 to 2:1 mole ratios. The maximum DBT conversion (wt.%) was at 2:1 mole ratio of acetic acid/sulfuric acid. This oxidation process is found to be capable of removing up to 90% of the sulfur compounds in hydro treated real fuels and can provide an alternative way to meet the future sulfur environmental requirements.     

Investigation into the removal of sulfur from tire derived fuel by pyrolysis

There is growing interest in the use of scrap tires as both a fuel and a feed material for petroleum feedstocks due to their abundance and their chemical composition. However, the sulfur content of scrap tires is a potential obstacle to scrap tires utilization as a fuel. In this paper, the partitioning of sulfur was investigated from the two major pyrolytic products from passenger car tires, liquid oils and solid chars, and the potential of producing a low sulfur char for fuel applications. The removal of sulfur during tire pyrolysis offers the greatest potential for the separation of sulfur products from the evolved gases and vapors. The influences of heating rate and pyrolysis temperature were investigated from 325 to 1000 °C, a range where substantial devolatilization occurs. The pyrolysis char and derived oil were analyzed for sulfur, and compared to the original parent sulfur content in tire derived fuel (TDF) samples. The results of sulfur determination verify that the overall desulfurization from the pyrolysis reaction is essentially unaffected by the heating rate but is affected by the ultimate pyrolysis temperature.     

Selective removal of sulfur compounds in city-gas by adsorbents

Silver nitrate impregnated on beta zeolite (BEA), mesoporous silica MCM-41 and SBA-15 (AgNO₃/BEA, AgNO₃/MCM-41, AgNO₃/SBA-15) were prepared to remove sulfur compounds selectively in city-gas, which contains tetrahydrothiophene and tert-butylmercaptane. Sulfur adsorption capacity was determined when the sulfur concentration of effluent gas in breakthrough test reached 0.1 ppm, which is acceptable sulfur concentration for hydrogen production in a reformer for fuel cells. As the AgNO₃ concentration in AgNO₃/BEA, AgNO₃/MCM-41, and AgNO₃/SBA-15 increased, their sulfur adsorption capacities also increased. Although microporous zeolite BEA has smaller pore volume and lower surface area than those of mesoporous silica MCM-41 and SBA-15, the sulfur adsorption capacity of AgNO₃/BEA was higher than those of AgNO₃/MCM-41 and AgNO₃/SBA-15. Adsorbed sulfur molecules per impregnated silver nitrate and the shape change of breakthrough curves depending on the adsorption temperature showed that not only chemisorption but also physisorption was involved in sulfur compounds adsorption on AgNO₃ impregnated adsorbent. This work was presented at the 6 ^th Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006.     

运输燃料脱硫吸附剂的研究进展

回顾了近几年来活性炭、分子筛、金属氧化物、介孔材料等运输燃料所用的脱硫吸附剂在制备方法、脱硫效果、吸附机理等方面的研究进展以及各类吸附剂在选择性、再生等方面的优缺点。指出了以后脱硫吸附剂的研究可能集中在吸附材料、制备方法和吸附机理三方面。     

Laboratory simulated slipstream testing of novel sulfur removal processes for gasification application

The Wabash River Integrated Methanol and Power Production from Clean Coal Technologies (IMPPCCT) project is investigating an Early Entrance Coproduction Plant (EECP) concept to evaluate integrated electrical power generation and methanol production from coal and other carbonaceous feedstocks. Research, development and testing (RD&T) that is currently being conducted under the project is evaluating cost effective process systems for removing contaminants, particularly sulfur species, from the generated gas which contains mainly synthesis gas (syngas), CO₂ and steam at concentrations acceptable for the methanol synthesis catalyst. The RD&T includes laboratory testing followed by bench-scale and field testing at the SG Solutions Gasification Plant located in West Terre Haute, Indiana. Actual synthesis gas produced by the plant was utilized at system pressure and temperature for bench-scale field testing.     

A novel method for oxidative desulfurization of liquid hydrocarbon fuels based on catalytic oxidation using molecular oxygen coupled with selective adsorption

The present study explored a novel oxidative desulfurization (ODS) method of liquid hydrocarbon fuels, which combines a catalytic oxidation step of the sulfur compounds directly in the presence of molecular oxygen and an adsorption step of the oxidation-treated fuel over activated carbon. The ODS of a model jet fuel and a real jet fuel (JP-8) was conducted in a batch system at ambient conditions. It was found that the oxidation in the presence of molecular oxygen with Fe(III) salts was able to convert the thiophenic compounds in the fuel to the corresponding sulfone and/or sulfoxide compounds at 25 °C. The oxidation reactivity of the sulfur compounds decreases in the order of 2-methylbenzothiophene > 5-methylbenzothiophene > benzothiophene  dibenzothiophene. The alkyl benzothiophenes with more alkyl substituents have higher oxidation reactivity. In real JP-8 fuel, 2,3-dimethylbenzothiophene was found to be the most refractory sulfur compound to be oxidized. The catalytic oxidation of the sulfur compounds to form the corresponding sulfones and/or sulfoxides improved significantly the adsorptivity of the sulfur compounds on activated carbon, because the activated carbon has higher adsorptive affinity for the sulfones and sulfoxides than thiophenic compounds due to the higher polarity of the former. The remarkable advantages of the developed ODS method are that the ODS can be run in the presence of O₂ at ambient condition without using peroxides and aqueous solvent and thus without involving the biphasic oil–aqueous-solution system.     

NH3 and HCl impact on sulfur removal from E-Gas™ gasification streams using S Zorb™ Gen. IV

This study is the third in a series examining the extension of the regenerable S Zorb™ SRT (Sulfur Removal Technology) system beyond sulfur removal from gasoline and into its application under warm-gas conditions. Previously, the fourth generation of this sorbent system was found to be effective and regenerable for the removal of up to 1 wt.% sulfur from a working gasifier product stream. In this study, the robustness of the system towards exposure to hydrogen chloride and ammonia was tested. The relationship between these compounds and the formation of zinc silicate and zinc sulfate within the sorbent was of particular interest since the formation of these phases most dramatically impacts the absorptive capacity of sulfur.     

Microbial removal of sulfur dioxide from a gas stream

A study of the feasibility of utilizing the Thiobacillus ferrooxidans or Desulfovibrio desulfuricans bacterium for microbial removal of sulfur dioxide from flue gases has been carried out. Sulfur dioxide may be readily reduced to H₂S by contact with sulfate-reducing microorganisms in which Desulfovibrio desulfuricans were dominant in the first stage. The H₂S was then oxidized to sulfur by the ferric sulfate in a second stage where ferrous ions were regenerated. These results were compared to microbial oxidation of SO₂ from flue gases to sulfate by Thiobacillus ferrooxidans. The mechanisms for the reduction of SO₂ to H₂S in the presence of Desulfovibrio desulfuricans and the oxidation of SO₂ to H₂SO₄ in the presence of ferric sulfate and Thiobacillus ferrooxidans are discussed. Sulfuric acid or gypsum CaSO₄ · 2H₂O are byproducts from microbial flue gas desulfurization.     

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.     

脱硫塔填料高度的计算方法

本文介绍填料脱硫塔填料高度的计算方法．     

The distribution of sulfur compounds in hydrotreated jet fuels: Implications for obtaining low-sulfur petroleum fractions

The mechanism by which jet fuels are hydrotreated to reduce sulfur levels has some important implications in terms of the species and distribution of sulfur compounds remaining in the fuel. The species of sulfur that are most difficult to remove by hydrotreating, such as benzothiophenes and methyl- and dimethyl-benzothiophenes, are concentrated in the higher-boiling fraction of the fuel. Consequently, the lower-boiling fractions of the fuel contain much less sulfur. It may be possible, therefore, to obtain petroleum fractions that contain low levels of sulfur simply by distillation of the jet fuel into low-boiling and high-boiling fractions. A multi-element simulated distillation procedure according to ASTM D-2887, standard test method for boiling range distribution of petroleum fractions by gas chromatography, was coupled with atomic emission detection (GC-AED) and was used to estimate the sulfur concentration in various fractions of jet fuel, namely 20, 50, and 60%. The estimations of sulfur concentration were verified by comparing them to analyzed sulfur concentrations in several fractions of physical distillations of the jet fuels according to a modified ASTM D-86, standard test method for distillation of petroleum products at atmospheric pressure. Sulfur analyses showed that for all fuels analyzed, the initial 20% boiling fraction of the fuel contained no more than approximately 5% of the total sulfur concentration. The initial 50% boiling fraction of the fuel contained no more than 25% of the total sulfur concentration, and in most cases contained significantly less (8-16%). The total concentration of sulfur in the jet fuels tested ranged from 260 to 1380 μg/g, and there did not appear to be a direct relationship between total sulfur concentration and percentage of sulfur in each jet fuel boiling fraction.     

Effectiveness of metal-organic frameworks for removal of refractory organo-sulfur compound present in liquid fuels

Adsorption of organo-sulfur compounds present in liquid fuels on metal-organic framework (MOF) compounds is an efficient alternative to the conventional hydrodesulfurization process. It has been demonstrated that the extent of dibenzothiophene (DBT) adsorption at temperatures close to ambient (304 K) is much higher on MOFs systems than on the benchmarked Y-type zeolite. In addition, the DBT adsorption capacity depends strongly on the MOF type as illustrated by the much higher extent of adsorption observed on the copper- (C300) and Al-containing (A100) MOF systems than on the Fe-containing (F300) MOF counterpart. With the aim to investigate the operation in consecutive cycles, the MOFs used in adsorption experiments were regenerated. In addition, the remaining S-containing compounds were identified and quantified by photoelectron spectroscopy (XPS). Examination of S2p core-level spectrum of the adsorbed S-compounds of regenerated MOFs pointed out that a fraction of these molecules become oxidized into S(VI) species.     

过氧磷钨酸催化氧化柴油深度脱硫实验研究

采用十六烷基三甲基溴化铵和磷钨酸反应制得过氧磷钨酸Q3+{PO4[W(O)O4]3[W(O)O4]}3-(Q3+为RH4+),以其为催化剂,H2O2为氧化剂,考察了该体系对柴油中含硫化合物的氧化脱除效果。结果表明,过氧磷钨酸具有较高的催化活性,在反应时间为60min,反应温度为60℃,V(H2O)∶V(柴油)=0.2,w(催化剂)=1.16%的条件下,柴油可脱硫率可达92.23%,动力学研究结果表明,催化氧化反应为表观一级反应。     

可循环再生吸附剂脱汞技术现状及发展趋势

总结了当前燃煤烟气脱汞常用的协同脱汞技术和贵金属、金属氧化物基可再生吸附剂技术发展现状,分析了各方法的优势与存在的问题,对未来磁性可回收吸附剂的发展方向和趋势进行了展望。针对现有脱汞技术效率低、易造成二次污染等缺陷,提出了使用飞灰磁珠制备廉价可回收脱汞吸附剂的新思路。通过大量试验开发了负载Co_3O_4或CuCl_2的磁珠改性方法以增强脱汞能力和抗烟气组分干扰能力,从而能够适用于低氯复杂烟气气氛。设计了改性磁珠吸附剂喷射脱汞工艺流程,可兼顾高效脱汞与低廉的运行成本,并通过磁珠回收再利用彻底避免汞进入环境造成污染。     

Development of sulfur tolerant catalysts for the synthesis of high quality transportation fuels

In this paper, results concerning the development of sulfur tolerant catalysts for Fischer–Tropsch synthesis (FTS), C₂₊ alcohol synthesis, methanol and/or DME synthesis are presented. In the FTS reaction on Fe using H₂-rich syngas such as the biomass-derived syngas, the composition of catalyst pretreatment gas and the addition of MnO on Fe had strong impacts on its sulfur resistance as well as activity. Especially the Fe/MnO catalyst pretreated with CO showed a much lower deactivation rate and a higher FTS activity than an Fe/Cu/K catalyst in the presence of H₂S. For C₂₊ alcohol synthesis a novel preparation method was developed for a highly active MoS₂-based catalyst that is well known as the sulfur tolerant catalyst. Besides some metal sulfides were found to show higher CO hydrogenation activities than MoS₂. In particular, both Rh and Pd sulfides were active and selective for the methanol synthesis. Modified Pd sulfide catalyst, i.e. sulfided Ca/Pd/SiO₂, showed an activity that was about 60% of that of a Cu/ZnO/Al₂O₃ catalyst in the absence of H₂S. This catalyst preserved 35% of the initial activity even in the presence of H₂S. The sulfided Ca/Pd/SiO₂ mixed with γ-Al₂O₃ was also available for in situ DME synthesis in the presence of H₂S.     

Polymer-based chelating adsorbents for the selective removal of boron from water and wastewater: A review

Boron removal from water is a highly interesting research area that has been addressed in various investigations in the recent years. This is due to the expansion of harmful effects of boron traces in water streams on the environment and human health with the rise in boron global demand in various industries that coincided with the implantation of more stringent water quality standards. Various technologies have been applied for the removal of boron from water solutions, including ion exchange technology, which has a great potential in treating varieties of boron-containing streams up to levels in parts per million using boron-selective adsorbents. This article comprehensively reviews the latest progress in the development of polymer-based boron-selective (chelating) materials and their applications for the removal of boron from water solutions, including commercial boron-selective resins (BSRs) and their researched counterparts. The emerging trends in the development of alternative adsorbents with different substrates, morphologies, and functional groups are also elucidated. The future directions to overcome the limitations of the present generation of resins are also discussed.     

A correlation for calculating HHV from proximate analysis of solid fuels

Higher heating value (HHV) and composition of biomass, coal and other solid fuels, are important properties which define the energy content and determine the clean and efficient use of these fuels. There exists a variety of correlations for predicting HHV from ultimate analysis of fuels. However, the ultimate analysis requires very expensive equipments and highly trained analysts. The proximate analysis on the other hand only requires standard laboratory equipments and can be run by any competent scientist or engineer. A few number of correlations of HHV with proximate analysis have appeared in the solid fuel literature in the past but were focused on one fuel or dependent on the country of origin. This work introduces a general correlation, based on proximate analysis of solid fuels, to calculate HHV, using 450 data points and validated further for additional 100 data points. The entire spectrum of solid carbonaceous materials like coals, lignite, all types of biomass material, and char to residue-derived fuels have been considered in derivation of present correlation which is given as below: HHV=0.3536FC+0.1559VM−0.0078ASH (MJ/kg) (where FC 1.0-91.5% fixed carbon, VM 0.92-90.6% volatile matter and Ash 0.12-77.7% ash content in wt% on a dry basis). The average absolute error of this correlation is 3.74% and bias error is 0.12% with respect to the measured value of HHV, which is much less than that of previous correlations of the similar kind. The major advantage of this correlation is its capability to compute HHV of any fuel simply from its proximate analysis and thereby provides a useful tool for modeling of combustion, gasification and pyrolysis processes. It can also be used in examining old/new data for probable errors when results lie much outside the predicted results.     

Ag+ ions imprinted cryogels for selective removal of silver ions from aqueous solutions

ABSTRACT

The removal of heavy metal ions from aquatic media or any conditions is crucial. Silver ions turn out to be the important example of this problem on earth when these are released to the environment. In the present study, silver ions (Ag⁺) imprinted poly(hydroxyethyl methacrylate) (PHEMA)-based cryogels were prepared using N-methacryloyl-L-cysteine as functional monomer, to be chelated with Ag⁺ ions. The maximum adsorption capacity of Ag⁺-imprinted polymeric cryogel was found to be 49.27 mg/g from aqueous solutions. To investigate the affinity of Ag⁺-imprinted PHEMAC cryogel column, photographic film material from the natural silver ion source was used. The recovery results were 72.8% for the Ag⁺-imprinted PHEMAC cryogel and 0.62% for the non-imprinted PHEMAC cryogels. These values clearly showed the selectivity of the Ag⁺-imprinted PHEMAC cryogel column. The adsorption–desorption cycle was performed more 10 times with use of the same Ag⁺-imprinted PHEMAC cryogel for the determination of reuse. These molecularly imprinted cryogels were used in adsorption process for a long time with no significant loss.     

采用有机盐─石膏脱硫剂的烟气脱硫新工艺

介绍一种利用有机羧酸盐作为吸收剂、以熟石灰作还原剂的烟气脱硫系统，在日本投入生产运行，其脱硫效率达９０％以上。     

Resistance to sulfur poisoning of hot gas cleaning catalysts for the removal of tar from the pyrolysis of cedar wood

In the partial oxidation of tar derived from the pyrolysis of cedar wood, the effect of H₂S addition was investigated over non-catalyst, steam reforming Ni catalyst, and Rh/CeO₂/SiO₂ using a fluidized bed reactor. In the non-catalytic gasification, the product distribution was not influenced by the presence of H₂S. Steam reforming Ni catalyst was effective for the tar removal without H₂S addition, however, the addition of H₂S deactivated drastically. In contrast, Rh/CeO₂/SiO₂ exhibited higher and more stable activity than the Ni catalyst even under the presence of high concentration of H₂S (280 ppm). On the Ni catalyst, the adsorption of sulfur was observed by XPS and Ni species was oxidized during the partial oxidation of tar. In the case of Rh/CeO₂/SiO₂, the adsorption of sulfur was below the detection limit of XPS. This can be related to the self-cleaning of catalyst surface during the circulation in the fluidized bed reactor for the partial oxidation of tar derived from cedar pyrolysis.