Hydrotreating of straight run gas oil–light cycle oil blends

A pilot plant study was conducted to evaluate the effect of up to 50 vol% light cycle oil (LCO) on product quality when it is used together with straight run gas oil (SRGO) as a hydrotreating feedstock. Experiments were carried out at reaction pressures of 54, 70 and 90 kg/cm²; reaction temperatures of 350, 360, 370 and 380°C, liquid hourly space velocity (LHSV) of 1.0, 1.5 and 2.0 h⁻¹, and constant hydrogen-to-oil ratio of 2000 ft³/bbl, over a commercial Co–Mo/γ-Al₂O₃ catalyst. The experimental results were used to determine apparent reaction orders and activation energies, which agree with those reported in the literature.     

Nitrogen compounds characterization in atmospheric gas oil and light cycle oil from a blend of Mexican crudes

The distribution of basic and non-basic nitrogen compounds along the distillation curves of the middle distillates atmospheric gas oil (AGO) and light cycle oil (LCO), used as feedstocks for diesel fuel production, is presented in this paper. For this purpose, the total and basic nitrogen content of true boiling point distillation fractions of AGO and LCO were obtained, followed by nitrogen compounds identification by a GC-MS technique. The ratio of quinoline, indole and carbazole derivatives was determined as 1/0.75/2.5 in AGO. In LCO, a 1/2.3/12.2 ratio of aniline, indole and carbazole derivatives was found. A complete physical and chemical characterization of both AGO and LCO is also presented.     

Combustion characteristics of droplets composed of light cycle oil and diesel light oil in a hot-air chamber☆

Development of gas turbines fueled with light cycle oil (LCO) and oil mixture of LCO and diesel light oil (LO) requires an understanding of the droplet burning and vaporization characteristics of those oils. The present study is devoted to comparing the burning characteristics of isolated fuel droplets composed of an LCO and an LO. The tests were conducted in an atmospheric hot-air chamber preset at 1173 K, and the examined LCO had a lower cetane number but higher volatility and aromatics content compared to LO. It was demonstrated that the burning of the LCO droplet was sootier, while that of the LO droplet was more disruptive. At the tested temperature, coke formation was indistinct for both the oils, whereas slightly higher ignition delay time was shown for the LO droplet. The microexplosive burning more or less complicated the time-series droplet size d, an explicit burning rate constant, however, was still definable according to the d²-law to show the overall regression speed of the droplet surface area d² with burning time t. The rate constant exhibited little difference for smaller LCO and LO droplets but was greater for LO when the droplet was larger. The rate constant also gradually increased with increasing the initial droplet diameter d₀, which caused the relative size d/d₀ to be unified (normalized) into a single curve by a burning time t/d₀ⁿ (1.0<n<2.0). Analysis revealed that this unification resulted from the respective overlaps of the unsteady and quasi-steady burning phases for differently sized droplets. Further, it was clarified that the unification and analysis are generally valid to isolated liquid fuel droplet burning in hot ambiences.     

MCM-41-supported Co-Mo catalysts for deep hydrodesulfurization of light cycle oil

Light cycle oil (LCO), a by-product of the fluid catalytic cracking (FCC) process in a petroleum refinery, can be used as a blendstock for the production of diesel and jet fuels. Regulatory and operational issues result in need for new and more active catalysts for the deep hydrodesulfurization (HDS) of diesel feedstocks, such as LCO. This paper reports the activity of a mesoporous molecular sieve MCM-41-supported Co-Mo catalyst in comparison to a commercial γ-alumina (Al₂O₃)-supported Co-Mo catalyst for the desulfurization of a LCO with a sulfur content of 2.19 wt.%. The HDS of dibenzothiophene, 4-methyldibenzothiophene, and 4,6-dimethyldibenzothiophene—polyaromatic sulfur compounds present in LCO—and their relative reactivities in terms of conversion were examined as a function of time on stream in a fixed-bed flow reactor. The MCM-41-supported catalyst demonstrates consistently higher activity for the HDS of the refractory dibenzothiophenic sulfur compounds, particularly 4,6-dimethyldibenzothiophene. The presence of a large concentration of aromatics in LCO appears to inhibit the HDS of the substituted dibenzothiophenes.     

Kinetic modeling of the hydrotreatment of light cycle oil and heavy gas oil using the structural contributions approach

The kinetics of the hydrodesulfurization of light cycle oil (LCO) and heavy gas oil (HGO) over a CoMo/Al₂O₃ catalyst were investigated in a perfectly mixed flow reactor with stationary basket of the Robinson-Mahoney type at temperatures of 330, 310 and 290 °C, H₂/HC molar ratios of 2.8, 3.6 and 7.2 and a pressure of 65 bar. Hougen-Watson type rate equations were derived for the conversion of dibenzothiophene, substituted (di)benzothiophene and their products. To avoid having to deal with a huge number of model parameters, a methodology based upon structural contributions was applied. In the absence of own kinetic data on key components a number of kinetic and adsorption parameters were taken from published work on a very similar catalyst. For a given value of H₂/HC only a small number of experiments was required to determine the value of the very complex denominators DEN_σ and DEN_τ appearing in the rate equations for the hydrodesulfurization of LCO and of HGO and of their evolution with the conversion of the feedstock. With the rate equations constructed in this way the calculated total conversion of DBT, its conversion into biphenyl and into cyclohexylbenzene were in excellent agreement with the experimental values.     

Y/composite titania-silica (CTS) supported catalyst for hydrotreating coker gas oil

Y/composite titania-silica (CTS) support was prepared by the in situ growth of CTS on HY zeolite. The effects of HY zeolite pretreatment and Y/CTS modification with P and F for adjusting the acidity of the support were studied. The results showed that the structure of Y/CTS was in the form of CTS as shell and HY zeolite particles as core. The content of HY zeolite affected the acidity, acidity distribution and pore structure of Y/CTS. The density of strong acid sites on the HY zeolite surface could be partly reduced by dealumination with citric acid. This reduced the CTS coverage on the outer surface of the HY zeolite, leading to the increased acidity of Y/CTS. The acidity distribution of the support could also be adjusted by P and F modification. Hydrotreating catalysts were prepared with Y/CTS as support. The catalysts were tested using the hydrotreating reaction of a coker gas oil (CGO). The experimental results showed that the catalyst hydrodenitrogenation (HDN) performance could be remarkably improved by adjusting the acidity of the catalyst support via HY zeolite pretreatment and P and F modification. The catalysts with proper Brönsted (B) acidity and Lewis (L) acidity behaved well in hydrodesulfurization (HDS) and HDN performances.     

An approach to the deep hydrodesulfurization of light cycle oil

Deep HDS of LCO to be <10 ppm was achieved by fractionating HDS. An LCO fraction having boiling point lower than 340 °C was easily hydrodesulfurized to be <10 ppmS under conventional HDS conditions because the hydrodesulfurization of the reactive sulfur species contained in the fraction was hardly inhibited by the aromatic compounds. In contrast, the heavier fraction was very hard to be hydrodesulfurized since its refractory sulfur species were strongly inhibited by large content of aromatic components. Dilution of the heavier fraction with common solvents showed higher reactivity over NiMo/Al₂O₃ catalyst than itself alone. Decalin, which showed the highest dilution effect, was believed to strip the strongly adsorbed aromatics off from the catalyst surface.     

New materials as FCC active matrix components for maximizing diesel (light cycle oil, LCO) and minimizing its aromatic content

Different materials such as sepiolite (magnesiumsilicate), amorphous silico-alumino-phosphate (ASAPO) or other mixed oxides such as SiO₂–ZrO₂, or SiO₂–Al₂O₃–MgO, are studied as potential active matrix components of a FCC catalyst, with the final objective of maximizing the light cycle oil (LCO) yield while minimizing the aromatic content of this fraction. The physico-chemical characteristics of these materials as well as their hydrothermal stability play a decisive role in their catalytic behavior. The high surface area amorphous SAPO stands out presenting high selectivity to LCO while decreasing the aromatics content as compared to a commercial SiO₂–Al₂O₃ used as reference material. A formulation has been simulated using this material and, after equilibration, its catalytic behavior has been compared to that of a conventional FCC catalyst formulation.     

Hydroprocesssing of light gas oil — rape oil mixtures

Two series of experiments of hydroprocessing of light gas oil - rape oil mixtures were carried out. The reactor feed was composed of raw material: first series — 10 wt.% rape oil and 90 wt.% of diesel oil; second series — 20 wt.% rape oil and 80 wt.% of diesel oil.     

FH-40系列轻质馏分油加氢精制催化剂研制及工业应用

成功开发出性能优异的FH-40A/FH-40B和FH-40C新一代轻质馏分油加氢精制催化剂，该系列催化剂具有孔容大、比表面积高、加氢活性好及堆积密度小等特点。在同等工艺条件下，达到相同精制效果，FH-40系列催化剂比国内外参比催化剂活性高［（10～15） ℃］。工业应用结果表明，FH-40系列催化剂对原料适应性强，具有优异的加氢脱硫和加氢脱氮活性，是加工轻质馏分油的理想催化剂。     

Hydrotreating of gas oil on SBA-15 supported NiMo catalysts

The siliceous and the metal substituted (B or Al)-SBA-15 molecular sieves were used as a support for NiMo hydrotreating catalysts (12 wt.% Mo and 2.4 wt.% Ni). The supports were characterized by X-ray diffraction (XRD), scanning electron microscopy and N₂ adsorption–desorption isotherms. The SBA-15 supported NiMo catalysts in oxide state were characterized by BET surface area analysis and XRD. The sulfided NiMo/SBA-15 catalysts were examined by DRIFT of CO adsorption and TPD of NH₃. The HDN and HDS activities with bitumen derived light gas oil at industrial conditions showed that Al substituted SBA-15 (Al-SBA-15) is the best among the supports studied for NiMo catalyst. A series of NiMo catalysts containing 7–22 wt.% Mo with Ni/Mo weight ratio of 0.2 was prepared using Al-SBA-15 support and characterized by BET surface area analysis, XRD and temperature programmed reduction and DRIFT spectroscopy of adsorbed CO. The DRIFT spectra of adsorbed CO showed the presence of both unpromoted and Ni promoted MoS₂ sites in all the catalysts, and maximum “NiMoS” sites concentration with 17 wt.% of Mo loading. The HDN and HDS activities of NiMo/Al-SBA-15 catalysts were studied using light gas oil at temperature, pressure and WHSV of 370 °C, 1300 psig and 4.5 h⁻¹, respectively. The NiMo/Al-SBA-15 catalyst with 17 wt.% Mo and 3.4 wt.% of Ni is found to be the best catalyst. The HDN and HDS activities of this catalyst are comparable with the conventional Al₂O₃ supported NiMo catalyst in real feed at industrial conditions.     

焦化蜡油加氢处理催化剂的研制

本文阐述了用于劣质焦化蜡油加氢处理催化剂的研制,并利用LTOC、TPR、XRD及TEM技术对所研制的催化剂进行了表征,同时对所研制的催化剂进行了活性和稳定性试验,取得了良好结果。目前该催化剂己应用在长岭炼油厂300kt/a加氢装置上,经济效益明显。     

Evaluation of the oxidation stability of diesel/biodiesel blends

Biodiesel is an alternative fuel derived from vegetable oils, animal fats and used frying oils. Due to its chemical structure, it is more susceptible to oxidation or autoxidation during long-term storage compared to petroleum diesel fuel. One of the major technical issues regarding the biodiesel blends with diesel fuel is the oxidation stability of the final blend, which is, nowadays, of particularly high concern due to the introduction of ultra low sulphur diesel, in most parts of the EU. This study examined the factors influencing the stability of several biodiesel blends with low and ultra low sulphur automotive diesel fuels. The aim of this paper was to evaluate the impact of biodiesel source material and biodiesel concentration in diesel fuel, on the stability of the final blend. Moreover, the effects of certain characteristics of the base diesels, such as sulphur content and the presence of cracked stocks, on the oxidation stability are discussed.     

A comparative study on the performance, emission and combustion studies of a DI diesel engine using distilled tyre pyrolysis oil–diesel blends

Alternate fuels like ethanol, biodiesel, LPG, CNG, etc., have been already commercialised in the transport sector. In this context, pyrolysis of solid waste is currently receiving renewed interest. The disposal of waste tyres can be simplified to a certain extent by pyrolysis. In the present work, the crude tyre pyrolyisis oil (TPO) was desulphurised and then distilled through vacuum distillation. Also, two distilled tyre pyrolysis oil (DTPO)–diesel fuel (DF) blends at lower and higher concentrations were used as fuels in a four stroke single cylinder air cooled diesel engine without any engine modification. The results were compared with diesel fuel (DF) operation. Results indicate that the engine can run with 90% DTPO and 10% diesel fuel.     

Comparative environmental behavior of bus engine operating on blends of diesel fuel with four straight vegetable oils of Greek origin: Sunflower, cottonseed, corn and olive

An experimental study is conducted to evaluate the use of sunflower, cottonseed, corn and olive straight vegetable oils (SVO) of Greek origin, in blends with diesel fuel at proportions of 10 vol.% and 20 vol.%, in a fully instrumented, six-cylinder, turbocharged and after-cooled, heavy duty (HD), direct injection (DI), ‘Mercedes-Benz’, mini-bus engine installed at the authors’ laboratory. The series of tests are conducted using each of the above blends, with the engine working at two speeds and three loads. Fuel consumption, exhaust smokiness and exhaust regulated gas emissions such as nitrogen oxides (NO_x), carbon monoxide (CO) and total unburned hydrocarbons (HC) are measured. With reference to the corresponding neat diesel fuel operation, the vegetable oil blends show reduction of emitted smoke with slight increase of NO_x and effectively unaffected thermal efficiency. Theoretical aspects of diesel engine combustion, combined with the very widely differing physical and chemical properties of the vegetable oils against those for the diesel fuel, aid to the correct interpretation of the observed engine behavior.     

An experimental investigation on a DI diesel engine using waste plastic oil with exhaust gas recirculation

Environmental degradation and depleting oil reserves are matters of great concern around the globe. Developing countries like India depend heavily on oil import of about 125 Mt per annum (7:1 diesel/gasoline). Diesel being the main transport fuel in India, finding a suitable alternative to diesel is an urgent need. In this context, waste plastic solid is currently receiving renewed interest. Waste plastic oil is suitable for compression ignition engines and more attention is focused in India because of its potential to generate large-scale employment and relatively low environmental degradation. The present investigation was to study the effect of cooled exhaust gas recirculation (EGR) on four stroke, single cylinder, direct injection (DI) diesel engine using 100% waste plastic oil. Experimental results showed higher oxides of nitrogen emissions when fueled with waste plastic oil without EGR. NO_x emissions were reduced when the engine was operated with cooled EGR. The EGR level was optimized as 20% based on significant reduction in NO_x emissions, minimum possible smoke, CO, HC emissions and comparable brake thermal efficiency. Smoke emissions of waste plastic oil were higher at all loads. Combustion parameters were found to be comparable with and without EGR. Compression ignition engines run on waste plastic oil are found to emit higher oxides of nitrogen.     

Impact of lubricating oil on particulates formed during combustion of diesel fuel—a shock tube study

The advent of more stringent standards to reduce particulate emissions has increased the need to control the contribution that consumption of lubricating oil in engines makes toward particle emissions. Although many studies have been done in this area, the main mechanism by which lubricating oil contributes to particle formation is not well understood. In this study, the impact of lubricating oil on particle emissions from diesel fuel combustion was investigated. Combustion of D-2 diesel fuel with two concentrations of Pennzoil 10W40 motor oil (0.5 and 2 wt%) was studied over a temperature range of 1200-2300 °C at pressures of 5, 14 and 24 atm. All experiments were conducted in a modified single pulse reflected shock tube. The fuel and lubricating oil mixtures were injected using a high pressure fuel injector. The addition of lubricating oil led to higher particulate yields at higher combustion pressures. The increase was more evident with higher lubricating oil concentrations. However, at lower pressures, neither concentrations of lubricating oil had any impact on particulate yield. The results agree with previous studies where an increase in particulate yield was observed with an increase in lubricating oil consumption and pressure. The results observed confirm the hypothesis that lubricating oil present in the combustion chamber during the combustion process could contribute to particle emissions.     

Alternate use of heavy hydrotreatment and visbreaker naphthas by incorporation into diesel

In order to provide a solution for refineries having limited catalytic reforming capacity, a process scheme for incorporating most of the low octane heavy hydrotreatment and visbreaker naphthas into diesel is presented in this paper. This scheme involves blending the visbreaker naphtha with the feed to the diesel hydrotreatment units, processing this blend at the usual conditions for diesel hydrodesulfurization and changing the cut point in the diesel stabilizer.     

HDS reactivities of dibenzothiophenic compounds in a LC-finer LGO and H2S/NH3 inhibition effect

The hydrodesulfurization (HDS) reactivities and the inhibition effects of H₂S and NH₃ were experimentally investigated for 11 difficult-to-remove sulfur compounds contained in LC-finer light gas oil using a commercial NiMo/Al₂O₃ hydrotreating catalyst. Among these sulfur compounds, 4-MDBT was the most reactive while 4,6-DMDBT was the least reactive. It was found that the presence of methyl groups away from the sulfur atom slightly enhanced the HDS reactivities of the methyl substituted DBTs. The observed low reactivity of 4,6-DMDBT was mainly caused by the steric hindrance of the two methyls at the 4 and 6 positions. Both H₂S and NH₃ significantly inhibited the HDS reaction rates for all 11 sulfur species of interest, while 4,6-DMDBT was one of the most inhibited species. At the same concentration (1.0 vol%), H₂S showed a stronger inhibition effect than NH₃. Measurable catalyst deactivation was observed in the course of the experiment that had a relatively even effect on the HDS of all reactants investigated in this study.     

Effects of ethyl tert-butyl ether addition to diesel fuel on characteristics of combustion and exhaust emissions of diesel engines

The effects of ethyl tert-butyl ether (ETBE) addition to diesel fuel on the characteristics of combustion and exhaust emissions of a common rail direct injection diesel engine with high rates of cooled exhaust gas recirculation (EGR) were investigated. Test fuels were prepared by blending 0, 10, 20, 30 and 40 vol% ETBE to a commercial diesel fuel. Increasing ETBE fraction in the fuel helps to suppress the smoke emission increasing with EGR, but a too high fraction of ETBE leads to misfiring at higher EGR rates. While the combustion noise and NO_x emissions increase with increases in ETBE fraction at relatively low EGR rates, they can be suppressed to low levels by increasing EGR. Though there are no significant increases in THC and CO emissions due to ETBE addition to diesel fuel in a wide range of EGR rates, the ETBE blended fuel results in higher aldehyde emissions than the pure diesel fuel at relatively low EGR rates. With the 30% ETBE blended fuel, the operating load range of smokeless, ultra-low NO_x (<0.5 g/kWi h), and efficient diesel combustion with high rates of cooled EGR is extended to higher loads than with the pure diesel fuel.