Fuel Processing Technology (v.91, #2)
Editorial Board (IFC).
Microwave applications to oil sands and petroleum: A review by Sateesh Mutyala; Craig Fairbridge; J.R. Jocelyn Paré; Jacqueline M.R. Bélanger; Siauw Ng; Randall Hawkins (127-135).
This review provides a general overview of microwave applications in oil sands bitumen or shale oil production in petroleum upgrading. The vast oil reserves in the oil sands of Alberta will become a major source of petroleum products in the near future and a number of alternative technologies have been explored for the production and upgrading of oil sands and heavy oil. This study is based primarily on the unique selective heating capacity associated with exposure of materials to microwaves. Of particular interest are applications of microwaves for bitumen extraction, upgrading heavy oils, removing heteroatoms, and the underground heating of oil sands to reduce bitumen viscosity and allow it to be pumped to the surface. The fundamentally different method of transferring energy from the source to the sample is the main advantage of utilizing microwave energy. By directly delivering energy to microwave-absorbing materials, conventional issues such as long heating periods and energy loses can be minimized. Microwave energy was shown to be effective in some applications; however, it is not used commercially at the present time.
Keywords: Microwave applications; Radio frequency; Petroleum upgrading; Microwave-assisted extraction; Oil sands;
Increasing carbon utilization in Fischer–Tropsch synthesis using H2-deficient or CO2-rich syngas feeds by Olusola O. James; Adediran M. Mesubi; Tiena C. Ako; Sudip Maity (136-144).
Fischer–Tropsch technology has become a topical issue in the energy industry in recent times. The synthesis of linear hydrocarbon that has high cetane number diesel fuel through the Fischer–Tropsch reaction requires syngas with high H2/CO ratio. Nevertheless, the production of syngas from biomass and coal, which have low H2/CO ratios or are CO2 rich may be desirable for environmental and socio-political reasons. Efficient carbon utilization in such H2-deficient and CO2-rich syngas feeds has not been given the required attention. It is desirable to improve carbon utilization using such syngas feeds in the Fischer–Tropsch synthesis not only for process economy but also for sustainable development. Previous catalyst and process development efforts were directed toward maximising C5+ selectivity; they are not for achieving high carbon utilization with H2-deficient and CO2-rich syngas feeds. However, current trends in FTS catalyst design hold the potential of achieving high carbon utilization with wide option of selectivities. Highlights of the current trends in FTS catalyst design are presented and their prospect for achieving high carbon utilization in FTS using H2-deficient and CO2-rich syngas feeds is discussed.
Keywords: Fischer–Tropsch synthesis; Biomass syngas; Carbon utilization; Selectivity; Zeolites; Hybrid catalyst systems;
New insights on the direct activation of isotropic petroleum pitch by alkaline hydroxides by E. Vilaplana-Ortego; M.A. Lillo-Ródenas; J. Alcañiz-Monge; D. Cazorla-Amorós; A. Linares-Solano (145-149).
The paper provides interesting evidences that a low softening point isotropic petroleum pitch can be used as a good carbon precursor for the preparation of activated carbons. The activation is carried out by KOH and/or NaOH and the resulting activated carbons present well developed porosity. Such hydroxide activations can be done directly on the pristine petroleum pitch (P) or on the pitch that has been submitted to an air stabilisation followed by a N2 heat treatment (TAN). In general, KOH activation produces better results than NaOH, both in terms of porosity and yield, the results obtained for the activation of TAN being impressive because of the good porosity developments and high yields reached. The different treatments carried out over the petroleum pitch precursor clearly show that they significantly influence the extent of microporosity development. This is due to different changes occurring in the porous structure of the precursor as a function of the treatment carried out. The efficiency of the activation process increases as the mesophase content of the precursor decreases, as well as the mesophase formation during the activation process is avoided.
Keywords: Isotropic pitch; Chemical activation; Microporosity; Activated carbon;
Geochemistry of fly ash from desulphurisation process performed by sodium bicarbonate by Helena Raclavska; Dalibor Matysek; Konstantin Raclavsky; Dagmar Juchelkova (150-157).
The application of NEUTREC® technology – desulphurisation by means of sodium bicarbonate – has been tested at the Trebovice coal-fired power plant (Ostrava, Czech Republic). This technology significantly influences the chemical composition of fly ash and the leachability of total dissolved substances (TDS), e.g., sulphates, fluorides and oxyanions (Se, Sb, Cr, As), which are monitored according to the Council of the European Union Decision 2003/33/EC. An increase of TDS in the water leachate from the fly ash obtained at 60% desulphurisation was influenced by sodium content, which is present in the form of Na+ ions (85–90%). The percentages of sodium sulphate and sodium carbonate were between 5 and 10% of the total sodium content. In order to decrease the leachability of TDS, sodium, sulphates and oxyanion mixtures were prepared containing a sorbent (60% bentonite) and mixed with desulphurised and non-desulphurised fly ash in various ratios. The addition of CaO resulted in the formation of a new mineral phase, burkeite. None of the applied technologies tested for the processed fly ash resulted in the preparation of a water leachate which complied in all monitored parameters to the requirements of Council Decision 2003/33 EC for nonhazardous wastes.
Keywords: Fly ash; Desulphurisation; NEUTREC®; Oxyanions; Leachability;
Sorption of mercury by activated carbon in the presence of flue gas components by Ir. Diamantopoulou; G. Skodras; G.P. Sakellaropoulos (158-163).
The purpose of the current study is to evaluate the mercury removal ability of F400 and Norit FGD activated carbons, through fixed bed adsorption tests at inert atmosphere (Hg° + N2). Additionally, adsorption tests were realized on F400 activated carbon, in the presence of HCl, O2, SO2 and CO2 in nitrogen flow. The obtained results, revealed that F400 activated carbon, with a high-developed micropore structure and increased BET area, exhibit larger Hg° adsorptive capacity compared to Norit. HCl and O2, can strongly affect mercury adsorption, owing to heterogeneous oxidation and chemisorption reactions, which is in accordance with the assumptions of some researchers. Additionally, SO2 presence enhances mercury adsorption, in contrast with the conclusions evaluated in other studies. The above result could be attributed to the possible formation of sulphur spaces on activated carbon surface and consist of a clarification for the role of SO2 on mercury adsorption. On the contrary, the mercury adsorption efficiency of F400 activated carbon showed a decrease at about 25%, with increasing CO2 concentration from 0 to 12%.
Keywords: Activated carbon; Elemental mercury; Flue gases;
Ultradispersed particles in heavy oil: Part I, preparation and stabilization of iron oxide/hydroxide by Nashaat N. Nassar; Maen M. Husein (164-168).
In this study, ultradispersed colloidal particles of iron oxide/hydroxide were prepared in-situ in heavy oil matrices adopting (w/o) microemulsion approach for nanoparticle preparation detailed in our previous work [1–3]. The effect of composition of heavy oil on the stable concentration of colloidal particles, particle uptake, was investigated. The following trends in particle uptake were common between the (w/o) microemulsions and the heavy oil matrices. An optimum water content was found for which a maximum particle uptake was attained. Particle uptake increased as the content of vacuum residue, VR, and precursor salt concentration increased. Vacuum residue contributes high asphaltene content, which acts as a surface active agent. The iron oxide/hydroxide particles had been recently shown to effectively remove H2S(g) from oil phase . H2S(g) is a hazardous by-product of heavy oil recovering and upgrading which should be removed as soon as it forms. Results pertaining to H2S(g) removal from heavy oil employing ultradispersed particles are communicated in Part II of this study.
Keywords: In-situ; Ultradispersed; Iron oxide/hydroxide; Heavy oil; Microemulsion; Uptake; Colloid;
Ultradispersed particles in heavy oil: Part II, sorption of H2S(g) by Nashaat N. Nassar; Maen M. Husein; Pedro Pereira-Almao (169-174).
During steam assisted gravity drainage for heavy oil recovery aqua-thermolysis reactions take place, whereupon gaseous hydrogen sulfide, H2S(g), is produced. A method to capture H2S(g) and convert it into a chemically inactive species is deemed necessary for sustaining in-situ recovery and upgrading. Part I of the current study explored the formation and stabilization of colloidal FeOOH particles in heavy oil matrices. In this Part, we evaluate the H2S(g) sorption ability of these particles as well as other metal oxide/hydroxide particles. Furthermore, the effect of mixing and temperature on H2S(g) sorption was investigated. Results showed that the rate and capacity of H2S(g) sorption increased as the concentration of FeOOH increased. Mixing, on the other hand, had insignificant effect on the sorption capacity, however it improved the sorption kinetics. In addition, in-situ prepared colloidal particles showed better reactivity towards H2S(g) than commercial α-Fe2O3 nanoparticles. Temperature had an adverse effect on the H2S(g) sorption capacity of FeOOH. This was attributed to a change in chemical structure of FeOOH as the temperature increased. Nevertheless, in-situ prepared ZnO colloidal particles completely removed H2S(g) even at high temperatures.
Keywords: H2S; Sorption; Heavy oil; Metal oxide; Sorbent;
Processing and kinetics studies on the alumina enrichment of coal fly ash by fractionating silicon dioxide as nano particles by Guanghui Bai; Wei Teng; Xianggang Wang; Hui Zhang; Peng Xu (175-184).
Coal fly ash produced in the northern China is a potential bauxite substitute for aluminum production because of its high alumina content. However, this industrial application has been limited for its high silicon content. Alumina enrichment by removing silicon becomes a key technology for its utilization. A novel process was developed to fractionate the coal fly ash into high purity nano silicon particles and aluminum enriched residual ash. The procedure has major steps as sodium silicate dissolution with sodium hydroxide, first carbonation to remove impurities, second carbonation to precipitate silicon, and silicon precipitate recovery as a mesospheric nano particles product. Morphological and X-ray diffraction evidences indicated the glassy amorphous silicon content of the ash was dissolved in the sodium hydroxide solution whereas mullite remained in the residue. Kinetics study indicated that the second carbonation was a kinetically second order medium fast multi-phase reaction in which sodium silicate was precipitated as silicic acid. It was found that the reaction was controlled by the mass transferring resistance in the liquid membrane. These nano silicon dioxide particles were in size of 50 nm with a purity of 96%. Alumina content in process residue was slightly increased from 42.00 to 49.20%. Silicon dioxide content was reduced from 48.89 to 30.26%. Ratio of alumina/silica was increased from 0.86 to 1.63.
Keywords: Coal fly ash; Desilication; Nano silicon dioxide; Two-step carbonation;
Effect of cobalt (nickel) content on the catalytic performance of molybdenum carbides in dry-methane reforming by Jinmin Cheng; Wei Huang (185-193).
The dry-methane reforming (DMR) behavior of Co–Mo and Ni–Mo carbide catalysts has been studied in order to establish the effect of the cobalt or nickel content of molybdenum carbide DMR catalysts. The results indicate that incorporating cobalt into the Mo2C structure at a Co/Mo ratio of 0.4, i.e. a Co0.4Mo1C x catalyst, gives a DMR activity and stability that are markedly higher than those of Mo2C catalysts. With respect to the Ni–Mo carbide catalysts, a Ni/Mo atom ratio of 0.2 (i.e. an Ni0.2Mo1C x catalyst), gives the maximum synergistic interaction between Ni and Mo. However, higher molar ratios decrease the promoting effect and facilitate the phase separation of the promoter. These results are proved by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy and N2-adsorption studies, and are also reflected in the poor catalytic stability of both the Co–Mo and the Ni–Mo carbide catalysts.
Keywords: Dry-methane reforming; Co–Mo carbides; Ni–Mo carbides; Promoting effect; Molybdenum carbide;
Transesterification of castor oil: Effect of the acid value and neutralization of the oil with glycerol by Louise L. Sousa; Izabelly L. Lucena; Fabiano A.N. Fernandes (194-196).
This paper evaluates the production of methyl esters from castor oil and methanol after neutralization of castor oil with glycerol. The reaction was carried out under atmospheric pressure and ambient temperature in a batch reactor, employing potassium hydroxide as catalyst. Results showed high yield of castor oil into methyl esters after neutralization of castor oil with glycerol. The highest yield observed was of 92.5% after 15 min of reaction. The best operating condition was obtained applying an alcohol to oil molar ratio of 6.0 and 0.5% w/w of catalyst.
Keywords: Biodiesel; Methyl esters; Castor oil; Transesterification; Methanolysis;
Experimental investigation of Gasoline-Like Fuel obtained from waste lubrication oil on engine performance and exhaust emission by Orhan Arpa; Recep Yumrutas (197-204).
Experimental investigation on engine performance and exhaust emission of a gasoline engine fueled by Gasoline-Like Fuel (GLF) was performed in this study. The GLF was obtained from waste lubrication oil (WLO) using the pyrolitic distillation method. Firstly, the WLO collected in a tank was particulates removed by a refining process. The refined lubrication oil samples were taken into a reactor and blended with calcium oxide (CaO) 2, 4, 6, 8, and 10 wt.% to remove sulphur in the oil. The blended samples were heated in the reactor and then distilled to decrease sulphur and to produce fuel samples. Distillation tests and characteristics of the produced fuel such as density, flash point and lower heating value were examined. The experimental results indicated that the CaO at 2 wt.% had the highest effect on decreasing the amount of sulphur content in the lubrication oil. Fuels produced using 2 wt.% CaO were separated into two parts which were light fuel with 20 wt.% and heavy fuel with 60 wt.% of the total WLO. Remaining of the WLO is about 20 wt.%, which is rejected from the reactor. The light fuel, referred to as GLF and gasoline samples are used to investigate the effect of the GLF on performance and emissions of a 1300 cm3 spark ignited engine manufactured by Fiat. The engine used in the study has specifications of four-stroke and four cylinders, water cooled, fueled with carburetor and naturally aspirated. Each cylinder has a bore of 76 mm and a stroke of 71.5 mm. The experimental results showed that the GLF had a positive effect on brake power, brake thermal efficiency, mean effective pressure and specific fuel consumption. The GLF also raised CO emission and exhaust temperature, but it decreased hydrocarbon (HC) in the exhaust.
Keywords: Waste oil; Gasoline fuel; Gasoline engine; Engine performance; Exhaust emission;
Biodiesel production from soybean oil and methanol using hydrotalcites as catalyst by Carla Cristina C.M. Silva; Nielson F.P. Ribeiro; Mariana M.V.M. Souza; Donato A.G. Aranda (205-210).
Esters of fatty acids, derived from vegetable oils or animal fats, and known as biodiesel, are a promising alternative diesel fuel regarding the limited resources of fossil fuels and the environmental concerns. In this work, methanolysis of soybean oil was investigated using Mg–Al hydrotalcites as heterogeneous catalyst, evaluating the effect of Mg/Al ratio on the basicity and catalytic activity for biodiesel production. The catalysts were prepared with Al/(Mg + Al) molar ratios of 0.20, 0.25 and 0.33, and characterized by X-ray diffraction (XRD), textural analysis (BET method) and temperature-programmed desorption of CO2 (CO2-TPD). When the reaction was carried out at 230 °C with a methanol:soybean oil molar ratio of 13:1, a reaction time of 1 h and a catalyst loading of 5 wt.%, the oil conversion was 90% for the sample with Al/(Mg + Al) ratio of 0.33. This sample was the only one to show basic sites of medium strength. We also investigated the reuse of this catalyst, the effect of calcination temperature and made a comparison between refined and acidic oil.
Keywords: Hydrotalcites; Biodiesel; Soybean oil; Transesterification;
Behaviour of heavy metals in the partial oxidation of heavy fuel oil by P. Brüggemann; F. Baitalow; P. Seifert; B. Meyer; H. Schlichting (211-217).
The behaviour of heavy metals in the partial oxidation of heavy fuel oils under a pressure of up to 100 bar (10 MPa) has been investigated. The tests were carried out in a 5 MW HP POX (High Pressure Partial Oxidation) test plant, that is operated by the IEC (Department of Energy Process Engineering and Chemical Engineering, TU Bergakademie Freiberg) in cooperation with Lurgi GmbH. In several test campaigns preheated oil with a viscosity of up to 300 cSt (= 300 mm2/s) at the burner inlet has been gasified. The heavy metals nickel Ni, iron Fe and vanadium V occur in heavy residual oils in considerable concentration and may seriously impact the gasification itself and the synthesis gas conditioning and usage. While iron is largely recovered in the gasification residue, the recovery rates of nickel and vanadium depend on the process conditions. Volatile nickel compounds were detected in the raw synthesis gas. It was found that an incomplete carbon conversion enables the capture of nickel Ni and vanadium V in the solid residue phase and can thus mitigate the problem of volatile metal compounds in the raw synthesis gas.
Keywords: Heavy oil gasification; Heavy metals; Nickel; Vanadium; Nickel carbonyl; Adsorption;
Optimization of a simplified sub-model for NO emission prediction by CFD in large 4-stroke marine diesel engines by Pia Kilpinen (218-228).
A simplified sub-model for NO emission prediction at pressurized conditions has been put forth at Åbo Akademi University [7,9] including NO formation via the thermal NO path (3 reactions) and via the nitrous oxide intermediate paths (2 + 5 reactions). CFD simulations carried out with the sub-model for marine and off-road diesel engines showed, however, that it significantly – by an order of magnitude – over-predicted NO emission as compared to measurements. The objective of this work was to find the reasons to the discrepancy and to suggest and incorporate improvements. By detailed investigations, a number of programming technical errors and chemical kinetic shortcomings were identified.The improved sub-model and its sub-parts were then tested for CFD simulation of a medium-speed, four-stroke, direct-injection marine diesel engine for different loads and fuels. The importance of NO reduction by soot and hydrocarbons was also investigated. All the sub-models correctly predicted the trend of increasing NO emission with increasing load. In absolute amounts, NO emission was over-predicted by a factor of 2 to 4, if no fitting of rate constants was allowed. Including NO reduction by soot and hydrocarbons, decreased NO emission by ca 4–25% for the cases studied.
Keywords: NO Emission; NO Formation; NO Reduction; CFD; Simulation; Marine diesel engine;
Adiabatic flame temperature from biofuels and fossil fuels and derived effect on NOx emissions by Pierre-Alexandre Glaude; René Fournet; Roda Bounaceur; Michel Molière (229-235).
There is currently a sustained interest in biofuels as they represent a potential alternative to petroleum derived fuels. Biofuels are likely to help decrease greenhouse gas emissions and the dependence on oil resources. Biodiesels are Fatty Acid Methyl Esters (FAMEs) that are mainly derived from vegetable oils; their compositions depend on the parent vegetables: rapeseed (“RME”), soybean (“SME”), sunflower, palm etc. A fraction of biodiesel has also an animal origin (“tallow”). A key factor for the use of biofuels in gas turbines is their emission indices (NOx, CO, VOC, and PM) in comparison with those of conventional “petroleum gasoils”. While biodiesels reduce carbon-containing pollutants, experimental data from diesel engines show a slight increase in NOx. The literature relating to gas turbines is very scarce. Two recent, independent field tests carried out in Europe (RME) and in the USA (SME) showed slightly lower NOx while a lab test on a microturbine showed the opposite effect. To clarify the NOx index of biodiesels in gas turbines, a study has been undertaken, taking gasoil and natural gas (NG) as reference fuels. In this study, a calculation of the flame temperature developed by the 3 classes of fuels has been performed and the effect of their respective compositions has been investigated. The five FAMEs studied were RME, SME and methyl esters of sunflower, palm and tallow; these are representative of most widespread vegetable and animal oil bases worldwide. The software THERGAS has been used to calculate the enthalpy and free energy properties of the fuels and GASEQ for the flame temperature (T f), acknowledging the fact that “thermal NOx” represents the predominant form of NOx in gas turbines. To complete the approach to structural effects, we have modeled two NG compositions (rich and weak gases) and three types of gasoil using variable blends of eleven linear/branched/cyclic molecules. The results are consistent with the two recent field tests and show that the FAMEs lie close to petroleum gasoils and higher than NG in terms of NOx emission. The composition of the biodiesel and regular diesel fuel influences their combustion heat: methyl esters with double bonds see a slight increase of their T f and their NOx index while that of gasoil is sensitive to the aromatic content.
Keywords: Biofuel; Conventional fuels; Gas turbine; Combustion; NOx; Flame temperature;
The influence of the process conditions on the characteristics of activated carbons obtained from PET de-polymerisation by M. Carmen Almazán-Almazán; Manuel Pérez-Mendoza; María Domingo-García; Inmaculada Fernández-Morales; F. Javier López; F. Javier López-Garzón (236-242).
In a previous paper we have reported a procedure to obtain active carbons by carbonisation of the residues obtained from the basic hydrolysis of poly(ethyleneterephthalate) (PET). Now we are getting insight into the relationships between the process parameters and the properties of the active carbons obtained by this procedure. Hydroxide/residue mass ratio, nitrogen flow rate, carbonisation time and carbonisation temperature are the process parameters which have been considered. It is shown that the textural properties of the activated carbons can be tailored by controlling such variables. Thus it is possible to obtain active carbons with a wide range of textural characteristics ranging from a molecular sieve to a sample with heterogeneous pore size but with high adsorption volume (0.8 cm3/g). This adds value to the procedure of obtaining active carbons from PET wastes. The textural characteristics have been determined by analysing the nitrogen and carbon dioxide adsorption isotherms. Several approaches have been applied to the isotherms, namely BET, Dubinin–Radushkevich, α s-plot and molecular simulation. Our results also show that all the approximations render similar textural characteristics when the micropore network is narrow, uniform and accessible. Nevertheless, it seems the α s-method overestimates micropore volumes in very activated carbons, as DR and molecular simulation render coincident values.
Keywords: PET; Basic de-polymerisation; Carbonization; Characterization;
Biodiesel production using alumina-supported calcium oxide: An optimization study by Masoud Zabeti; Wan Mohd Ashri Wan Daud; Mohamed Kheireddine Aroua (243-248).
This study consists of the optimization of the methyl ester yields produced via transesterification of palm oil using CaO/Al2O3 solid base catalyst. Response Surface Methodology (RSM) in combination with Central Composite Design (CCD) was used to optimize the operating parameters. Alcohol/oil molar ratio, catalyst content in the reaction medium and reaction temperature were chosen as the variables and the response selected was the amount of methyl ester yields. All the reactions were performed in a batch laboratory scale reactor for 5 h; the optimum reaction conditions obtained were approximately alcohol/oil molar ratio of 12:1, catalyst content of 6 wt.% and reaction temperature of 65 °C. The results from ICP-MS exhibited insignificant leaching of the CaO active species into the reaction medium and the reusability of the catalyst was successfully tested in two subsequent cycles. Under certain reaction conditions the glycerol obtained was almost colorless.
Keywords: Biodiesel; Calcium oxide; Catalyst leaching; Optimization; Palm oil;
Acetylation of glycerol to synthesize bioadditives over niobic acid supported tungstophosphoric acid catalysts by M. Balaraju; P. Nikhitha; K. Jagadeeswaraiah; K. Srilatha; P.S. Sai Prasad; N. Lingaiah (249-253).
Acetylation of glycerol to yield mono, di and triacetin (acetylated glycerol) was carried over niobic acid supported tungstophosphoric acid (TPA) catalysts. The catalysts with varying TPA content were prepared and characterized by different techniques. The characterization results reveal the presence of well-dispersed Keggin ion on support. The results suggest that the glycerol conversion and selectivities depend on the acidity of the catalysts, which in turn is related to the content of TPA on niobic acid. The change in conversion and selectivities during the acetylation also is attributed to the reaction time, catalyst concentration and glycerol to acetic acid molar ratio.
Keywords: Glycerol; Acetylation; Acetic acid; Tungstophosphoric acid; Niobic acid;