Fuel Processing Technology (v.113, #C)

Catalytic effects of Na and Ca from inexpensive materials on in-situ steam gasification of char from rapid pyrolysis of low rank coal in a drop-tube reactor by Li-xin Zhang; Shinji Kudo; Naoto Tsubouchi; Jun-ichiro Hayashi; Yasuo Ohtsuka; Koyo Norinaga (1-7).
Cost of catalysts is a crucial factor in realizing coal catalytic gasification process. In this study, inexpensive raw materials, soda ash (Na2CO3) and slaked lime (Ca(OH)2), were selected as catalyst precursors, and Na-, Ca- and Ca/Na-loaded coals were prepared by an ion-exchange procedure using a sub-bituminous coal (Adaro coal, Indonesia). These coal samples were rapidly pyrolyzed and in-situ gasified in an atmospheric drop-tube reactor (DTR) at 850–1000 °C under a steam partial pressure of 0.05 MPa. The Na and Ca catalysts showed remarkable activity for gasification, and the Ca/Na-loaded coal exhibited the highest reactivity among the coal samples prepared. The char yield of the Ca/Na-loaded coal at 1000 °C was as low as 17.6 mol-C per 100 mol-C of coal, and more than 70% (on carbon basis) of its primary char was gasified within 3 s. At 900 °C, the coal with Ca-loading of 3.2 wt.% showed catalytic activity higher than the coal with Ca-loading of 0.52 wt.%. At 950 and 1000 °C, however, the coal with the lower Ca-loading showed higher activity. The XRD analysis suggested that the Ca catalyst with the lower loading was more resistant to coarsening along with the progress of char gasification.
Keywords: Steam gasification; Drop-tube reactor; Low rank coal; Catalyst loading; Soda ash; Slaked lime;

Continuous estimation of kerosene cold filter plugging point using soft sensors by Mirjana Novak; Ivan Mohler; Marjan Golob; Željka Ujević Andrijić; Nenad Bolf (8-19).
Due to growing fuel quality demands, continuous measurements of process variables and product quality properties in the crude distillation unit (CDU) are necessary. One of the key diesel fuel properties is kerosene cold filter plugging point (CFPP). CFPP is usually determined only by laboratory assays. On the basis of available continuous measurements of temperatures and flows of appropriate process streams, soft sensor models for the estimation of kerosene CFPP have been developed. Data preprocessing includes: detection and outlier removal, generating additional output data by Multivariate Adaptive Regression Splines (MARSplines) algorithm, detrending data and filtering data. Soft sensors are developed using linear and nonlinear identification methods. Model structures are optimized by Genetic Algorithm (GA) and ANFIS (Adaptive Neuro-Fuzzy Inference System) algorithm. Results of the Output Error (OE) model, Hammerstein–Wiener (HW) model and neuro-fuzzy model are shown. Developed models were evaluated based on the final prediction error (FPE), root mean square error (RMSE), mean absolute error (AE) and FIT values. The best results are achieved with neuro-fuzzy model.
Keywords: Soft sensor; Neural fuzzy model; Model identification methods; Crude distillation unit; Cold filter plugging point;

The paper presents the results of the experimental research conducted on an industrial scale and directed at stabilizing the process of the thermal destruction of biomass in the form of animal post-slaughter waste and dead animals. During the realization of the combustion process with the participation of oxygen from 6 to 17% the interaction between such gas products of the process of thermal destruction as SO2 and HCl was analyzed. The results of the experiment clearly indicate that the concentration of SO2 in flue gas is dependent on the participation of O2 in the process of combustion. Hydroxyapatites in the high temperature atmosphere were decomposed, among others, to CaO and P2O5. Particles of CaO, in largely oxidizing atmosphere, carried in the stream of exhaust gases bonded SO2. When the participation of O2 oscillates around 16 to 17%, the concentration of SO2 is close to zero. However, at the same time there are no clear premises concerning the influence that the participation of O2 has on the concentration of HCl. The results in the form of the dependence HCl → f(O2) only suggest that the concentration of HCl in outlet gases decreases for large participation of oxygen of more than 13%.
Keywords: Animal waste; Thermal destruction; Hydroxyapatite; Interaction SO2; HCl; Reduction emission;

Catalytic behavior of Ni-modified perovskite and doped ceria composite catalyst for the conversion of odorized propane to syngas by Massimiliano Lo Faro; Vincenza Modafferi; Patrizia Frontera; PierLuigi Antonucci; Antonino S. Aricò (28-33).
The catalytic activity of a Ni-modified perovskite (LSFCO) — ceria doped gadolinia composite catalyst in the presence of odorized propane has been studied in order to assess this material as catalyst for a fuel processor in Solid Oxide Fuel Cells (SOFCs). At first, the study involved the investigation of the catalytic activity in the presence of propane in different reaction conditions and temperatures. Once established the best reaction conditions, the catalytic stability in an endurance test, and subsequently the effect on the catalytic performance of adding different amounts of H2S, has been explored. The autothermal reforming (ATR) at 800 °C has provided the highest performance (99% C3H8 conversion, 67% H2 and 17% CO yields). The upper limit of H2S content in propane for which the performance of such catalyst is still acceptable in terms of propane conversion and syngas yield is 80 ppm. Accordingly, the level of sulfur contaminants tolerated by this catalyst is much higher than that of conventional Ni-based catalyst for similar conversion and syngas yield.Display Omitted
Keywords: Sustainable chemistry; Perovskite phases; Sulfur; Heterogeneous catalysis; Nanoparticles; Fuel cells;

Potassium catalyzed CO2 gasification of petroleum coke at elevated pressures by Maryam Malekshahian; Josephine M. Hill (34-40).
The rate of gasification can be increased by the addition of an alkali metal catalyst such as potassium. The effectiveness of potassium, however, depends on the characteristics of the feed material and the operating conditions. In this study, the effect of total pressure and partial CO2 pressure on the gasification rate of K-impregnated petroleum coke was studied. Both raw petroleum coke and the produced char were impregnated with potassium carbonate at different loadings (0.03, 0.06, 0.10, 0.16 K/C molar ratio). The CO2 gasification experiments were performed in a high-pressure thermogravimetric analyzer at different temperatures (998 to 1098 K) and pressures (0.1 to 2.1 MPa), while the samples were characterized with Fourier transform infrared spectroscopy and inductively coupled plasma analysis. The rate increased with increasing pressure because of decreased catalyst volatilization and increased catalyst distribution. The determined activation energies at 0.1 MPa were 254 ± 21 kJ/mol and 133 ± 17 kJ/mol, for K-impregnated char and petroleum coke, respectively. The impregnation of potassium was more effective on raw petroleum coke because petroleum coke had more surface functional groups and a less ordered crystal structure than char.
Keywords: Catalytic gasification; Potassium; Petroleum coke; Pressure; Pre-treatment;

Improving stability of concentrated coal–water slurry using mixture of a natural and synthetic surfactants by Debadutta Das; Uma Dash; Jibardhan Meher; Pramila K. Misra (41-51).
The use of a surfactant mixture of natural and synthetic surfactants as additives in stabilizing coal-water slurry (CWS) formed from low rank Indian coals has been explored. The surface activities of the synthetic surfactants, hexadecyltrimethyl ammonium bromide (CTAB, cationic surfactant) and sodium dodecyl sulphate (SDS, anionic surfactant) are found to alter when various concentrations of natural surfactant, saponin (non-ionic surfactant) extracted from the fruits of Sapindous laurifolia are added to them independently. A considerable decrease in viscosity of CWS has been observed on the addition of saponin to the synthetic surfactants, CTAB/SDS (at 50:50 (w/w) for saponin:CTAB; 60:40 (w/w) for saponin:SDS systems). The mixture of anionic-nonionic is however, found to be more effective than the mixture of cationic-nonionic surfactants in reducing the apparent viscosity of the mixtures. The surface tension and contact angle data of the mixtures in solution suggest the high surface activity of the mixtures at these ratios. The rheological behaviors of CWS at weight concentrations varying from 55% to 65% wt.%, the static stability test, effect of pH, temperature, etc. have been studied. The slurries follow Bingham plastic behavior within these ranges of concentrations. A qualitative model of interaction of additive with a coal particle at the interface has been suggested.
Keywords: Surfactant mixture; Additive in coal–water slurry; Saponin; Coal–slurry stabilization; Rheological behavior; Natural surfactant;

Adsorption of Paenibacillus polymyxa and its impact on coal cleaning by M.A. Abdel-Khalek; A.A. El-Midany (52-56).
The adsorption of micro-organisms and bacteria on minerals surfaces depends mainly on the type of the bacteria used as well as the nature of the studied mineral surface. Such adsorption could change the surface properties of the mineral surface and leads to control its surface for increasing its separation selectivity from associated impurities or enhance/retard the adhesion with other substances. Therefore, in the current study, adsorption of Paenibacillus polymyxa (P. polymyxa) on coal was studied. Several methods were used such as: zeta potential, adsorption isotherms, adsorption kinetics and Fourier Transform InfraRed (FTIR). The main goal is to determine the difference in surface behaviour of coal particles before and after the treatment with P. polymyxa bacteria. The results showed that electrostatic interactions are insignificant in P. polymyxa adsorption on coal particles. The results suggest that the adsorption of bacteria on the coal particles is mainly physical and it depends on electrostatic forces, hydrogen bonding as well as the hydrophobic forces between the bacteria wall and the organic matter in the coal and coal hydrophobicity.
Keywords: Adsorption; Coal; Paenibacillus polymyxa; Separation; Ash; Sulphur;

Bio-fuel production provides an alternative non-fossil fuel without the need to redesign current engine technology. This study presents an experimental investigation into the effects of using biodiesel blends on diesel engine performance and its emissions. The biodiesel fuels were produced from sunflower oil using the transesterification process with low molecular weight alcohols and sodium hydroxide then tested on a steady state engine test rig using a Euro 4 four cylinder compression ignition (CI) engine. This study also shows how by blending biodiesel with diesel fuel at intervals of B5, B10, B15, and B20 can decrease harmful gas emissions significantly while maintaining similar performance output and efficiency. Production optimization was achieved by changing the variables which included methanol/oil molar ratio, NaOH catalyst concentration, reaction time, reaction temperature, and the rate of mixing to maximize biodiesel yield. The technique used was the response surface methodology (RSM). In addition, a second-order model was developed to predict the biodiesel yield if the production criteria is known. The model was validated using additional experimental testing. It was determined that the catalyst concentration and molar ratio of methanol to sunflower oil were the most influential variables affecting percentage conversion to fuel and percentage initial absorbance.
Keywords: Biodiesel; Transesterification; Response surface methodology; Sunflower oil; Engine performance and emission;

The susceptibility of coal to spontaneous combustion is a physical–chemical property of coal that can be determined by a laboratory test. A number of laboratory methods verifying the coal susceptibility to spontaneous combustion exist, e.g. the oxidation method under adiabatic conditions, method according to the author Olpinski, method of pulse calorimetry, and CPT (Crossing Point Temperature) method. Any versatile method has not been so far developed, which would become a generally respected and utilized laboratory procedure of objective assessment. The paper deals with the verification of the widely used adiabatic oxidation method. The modification of the method in question consists in the adjustment of the test process by increasing the initial temperature. This procedure enables shortening the test process. Shortening the laboratory test duration creates conditions for wider utilization of the method in practice. The paper presents results of 36 tests of Ostrava–Karvina Coalfield coal samples which confirmed an applicability of the modified adiabatic method in practice.
Keywords: Spontaneous combustion of coal; Adiabatic method; Susceptibility; Self heating;

Simplified model of the CO2/CH4 exchange sorption process by Juliusz Topolnicki; Mateusz Kudasik; Barbara Dutka (67-74).
The necessity to reduce the increasing amounts of carbon dioxide (CO2) in the atmosphere entails searching for some effective methods that enable safe storage of the gas in question. A method known as enhanced coal bed methane recovery (ECBM), involving injection of CO2 into unexploited coal beds, makes it possible to obtain CH4, too. The ECBM method is based on the exchange sorption phenomenon. The present paper provides a numerical model describing the process of the CO2/CH4 exchange sorption on coal briquette. The model is based on a number of hypotheses. It was assumed that the exchange sorption occurs on the surface, between the sides of grain and the sorbent macropores. Certain hypotheses were formed as to the kinetics of the exchange sorption process, as well as the impact of its consecutive stages on the filtrational transport of a gas mixture through the network of macropores. The presented model of exchange sorption is a system of equations, solved numerically. Simulations carried out by means of the thus constructed model were compared with the results obtained in the course of laboratory experiments into the CO2/CH4 exchange sorption on coal briquette.
Keywords: ECBM; Exchange sorption; Coal briquette; Modeling; Numerical simulation;

Co-firing of coal and biomass appears as a promising technology to improve CO2 emission levels. Even though it has been extensively studied, there is a need of widening the range of biomass fuels that could be applied to the process. With this aim, two energy crops (cynara and poplar) were tested with coal in a 500 kW th co-firing pilot plant and compared from an emission viewpoint. Energy crops were co-fired with a bituminous coal at different shares (0–15%) in energy basis, and flue gas concentration (CO, CO2, SO2, O2 and NO x ) was measured at stack.Combustion efficiency was evaluated by means of CO concentration, showing good performance in all cases and proving the feasibility of the process with low emissions. Small differences in particle size distribution are probably the main cause of different CO trends as cynara share is increased. SO2 levels decreased for both cases, although, as expected, the SO2 reduction was more pronounced for poplar co-firing than for cynara. NO x emissions were higher in poplar experiments than in cynara mainly due to volatile matter content and air distribution differences. This work also includes a comparison with similar experimental results from literature, where high data variability was found.
Keywords: Biomass; Cynara; Poplar; Coal; Emissions; Co-firing; Pulverized fuel; Swirl burner;

Catalytic coal-tar decomposition to enhance reactivity of low-grade iron ore by Rochim B. Cahyono; Alya N. Rozhan; Naoto Yasuda; Takahiro Nomura; Sou Hosokai; Yoshiaki Kashiwaya; Tomohiro Akiyama (84-89).
Effective utilization of low-grade iron ore and coal can be one of the solutions for avoiding the high cost of raw materials and solving the problem of resource shortages in the steelmaking industry. This paper describes the behavior of reduction reaction during tar decomposition over low-grade iron ore. Pisolite ore, containing 5.9 mass% of combined water, was dehydrated at 450 °C to obtain porous ore. Tar vapor and pyrolysis gas of low-grade coal were introduced to porous ore for tar decomposition and carbon deposition. The iron ore effectively decomposed 22.1 mass% of tar component into gas product and deposited carbon at 600 °C. Besides tar decomposition, the ore was also reduced to magnetite and wustite by gas product which was produced from coal pyrolysis and tar decomposition. The reactivity of deposited carbon within ore was evaluated by reduction reaction using thermogravimetry method. The reduction of the carbon-deposited ore began at 750 °C, while that of the reference mixture of Fe3O4 and coke began at 1100 °C. The carbon-deposited iron ore was more reactive because nanoscale contact between iron ore and carbon enhanced reaction rate. These results revealed attractive utilization and reduction process of low-grade iron ore with coal tar decomposition.
Keywords: Ore reduction; Tar decomposition; Carbonization; Ironmaking;

Volatilization characteristics of solid recovered fuels (SRFs) by Daniel Montané; Sònia Abelló; Xavier Farriol; César Berrueco (90-96).
The volatilization characteristics of three MSW-derived materials (FO, RT and FL) produced by local waste-management companies were investigated as potential solid recovered fuels (SRFs). FL was prepared from sorted domestic waste and consisted of non-recyclable plastics, refuse paper and biomass. RT and FO were obtained through active hygienization of unsorted MSW and refuse materials from selective waste-collection streams. RT was rich in plastics and had low biomass, whereas FO was mainly biomass and refuse paper. The rate of energy release during volatilization depended on the content of biomass and plastic, especially at a low conversion. Major contaminants had different rates of volatilization. Nitrogen and sulfur tended to accumulate in the charred solid, and were released as SO2 and nitrous oxides during both the volatilization–combustion stage and the char burning stage. Chlorine release was faster for the fuels rich in plastic waste. According to their ash melting characteristics and slagging indexes (Fs: 1188 °C for FO, 1192 °C for RT and 1234 °C for FL) the three fuels were equivalent to commercial SRFs. The three fuels showed potential as standardized SRF, although it would be desirable to reduce their chlorine content and, in the case of FO, to increase it’s heating value.
Keywords: Solid recovered fuel; Combustion; Gasification; Pyrolysis; Fuel volatilization;

This paper considers the option to convert the diesel engine to LPG retaining the diesel-like behaviour. LPG is an alternative fuel with a better carbon to hydrogen ratio permitting reduced carbon dioxide emissions. It flashes immediately to gaseous form even if injected in liquid state for a much cleaner combustion almost cancelling some of the emissions of the diesel. Within Australia, LPG permits a much better energy security and the refueling network is widespread. In this paper, a latest heavy duty truck diesel engine with a novel power turbine connected through a continuously variable transmission to the crank shaft and fitted with a by-pass is modified to accommodate a second direct injector for the LPG fuel and operate full load with 5% diesel and 95% LPG. Results of engine performance simulations with diesel and diesel-LPG are presented. The engine retains the diesel performances while permitting the advantages of LPG in terms of particulate, carbon dioxide emissions and diversification of fuel supplies and energy security.
Keywords: Diesel engines; LPG; Alternative fuels; Power turbine;

Simple and sensitive method for the measurement of volatile alkyl mercaptans in gasoline for remote field deployment by Siranoush Shahrzad; James Ford; Cheryl Sagara; Martin Flatley (109-113).
Trace sulfur species, such as elemental sulfur, hydrogen sulfide, and volatile alkyl mercaptans, adversely affect silver based devices, such as gasoline level sensors, used in most vehicles. Identification and measurement of the sulfur species are key to developing a process control and/or treatment system to solve the problem at the refinery, prior to product distribution. A new and innovative method was developed for the analysis of specific mercaptan species in gasoline, and is reported here. The initial sample treatment stage is precipitation and stabilization of mercaptans as silver mercaptides. This stabilization could be successfully utilized in the field to mitigate the instability of mercaptans in gasoline samples. Another advantage of this step is that silver nitrate (AgNO3) precipitation concentrates the mercaptans allowing for trace level detection. The silver mercaptides are converted to pentafluorobenzyl derivatives and analyzed by gas chromatography (GC) with mass spectrometric (MS) detection. Results based on this technique show that alkyl mercaptans can be accurately measured in the full scan mode of MS with a limit of detection (LOD) of 0.02 mg/L when a 100 mL gasoline sample is used. The recovery of mercaptans spiked into gasoline was 85 to 120% (n = 5). Gasoline producers will find knowing the exact levels of mercaptans in their products a useful tool to avoid distribution delays.
Keywords: Mercaptans; Gasoline; Pentafluorobenzyl bromide; GC/MS;

Recent research on mineral carbonation has focused attention on multi-step processes which appear more attractive than single-step processes due to the higher purity of the final products. Recent studies on mineral carbonation have indicated that industrial wastes can require a lower degree of pre-treatment and less energy-intensive carbonation conditions, in comparison to mineral rocks. In light of this, a closed-loop, multi-step process which allows precipitation of calcium carbonate (CaCO3) from Ca-rich waste streams has been developed. The main objective of this work is to focus on mineral dissolution kinetics for steel slag and recycled concrete aggregate, to confirm the formation of CaSO4(s) for the following carbonation reaction. Dissolution studies using ammonium bisulphate (NH4HSO4) solutions were carried out at three different temperatures (25–50–90 °C). For the steel slag sample, solid crystals of CaSO4 were produced on the surface of the reacted particles of the starting material. Mg and Fe, instead, dissolved into solution and their efficiencies of dissolution, after 3 h at 90 °C, were 85% and 90% respectively. Kinetic analyses found that the Avrami model, which explains the diffusion process for systems in which crystallization occurs on the sample surface, can accurately represent the kinetics of steel slag dissolution. The calculated activation energy was 42 kJ/mol. Dissolution of recycled concrete aggregate into an NH4HSO4 solution, as for steel slag, produced precipitated CaSO4, while aluminium, the other main metal present, dissolved partially (40% at 25 °C) into solution. For the recycled concrete aggregate, the Avrami model fitted best the results from dissolution experiments. However, because of the low values of R2 at 25 °C and 90 °C, the Avrami model cannot be considered valid in terms of the kinetic of the reaction and further investigations are needed to corroborate precipitation of crystals of CaSO4 on the surface of RCA samples.
Keywords: Mineral carbonation; Ammonium bisulphate; Dissolution; Steel slag; Recycled concrete aggregate;

Supported ionic liquid membrane and liquid–liquid extraction using membrane for removal of sulfur compounds from diesel/crude oil by Garba O. Yahaya; Feras Hamad; Ahmed Bahamdan; Veera V.R. Tammana; Esam Z. Hamad (123-129).
The feasibility of using liquid–liquid extraction with membrane (LLEM) and supported ionic liquid membranes (SILMs) for the desulfurization of hydrocarbon streams, such as raw diesel and whole crude oil, was investigated separately and for each, separation capability and mass transfer rate were studied. The SILM study using ionic liquid (IL) to remove sulfurous species from hydrocarbons exhibits very low mass transfer coefficients. However, the use of extractive liquids, such as furfural and naphtha, in LLEM boosts the transfer rate of sulfurous species as compared to IL as indicated in the high value of mass transfer coefficient (k). Furthermore, the mass transfer coefficient (k) shows significant dependence on the flow rate of both feed stock and extractive liquid streams, as the mass transfer coefficient of sulfurous compounds increased with increase in the flow rate of either stream or both. The mass transfer resistance offered by the membrane is also significant as clearly indicated by increase in mass transfer coefficient with increasing membrane pore size. In addition, when furfural is used with crude oil as feed, the fouling on the membrane surface from the crude oil side is significant, which limits the transfer rate. However, light naphtha is more promising to act as an extractive liquid as it transfers under the osmotic pressure difference to the whole crude oil side, which prevents fouling and thus promotes faster diffusion of sulfurous species.
Keywords: Supported liquid membrane; Membrane contactor; Liquid–liquid extraction; Desulfurization; Sulfur compounds; Hydrocarbons;

In this work, mixtures of vacuum gas oil and low density polyethylene, a major component of common industrial and consumer household plastics, were pyrolytically co-processed in a fluid catalytic cracking (FCC) riser reactor as a viable alternative for the energy and petrochemical revalorisation of plastic wastes into valuable petrochemical feedstocks and fuel within an existing industrial technology. Using equilibrium FCC catalyst, the oil–polymer blends were catalytically cracked at different processing conditions of temperatures between 773 K and 973 K and catalyst feed ratios of 5:1, 7:1 and 10:1. The influence of each of these processing parameters on the cracking gas and liquid yield patterns were studied and presented. Further analysed and presented are the different compositional distributions of the obtained liquids and gaseous products. The analysis of the results obtained revealed that with very little modifications to existing process superstructure, yields and compositional distributions of products from the fluid catalytic cracking of the oil–polymer blend in many cases were very similar to those of the processed oil feedstock, bringing to manifest the viability of the feedstock co-processing without significant detriments to FCC product yields and quality.
Keywords: Vacuum gas oil; Polyethylene; Fluid catalytic cracking; Riser reactor; FCC catalyst;

The synthesized catalyst comprising 12-tungstophosphoric acid anchored to two different mesoporous silica supports, MCM-41 and SBA-15, was characterized and used as heterogeneous acid catalyst for biodiesel production by esterification of oleic acid with methanol. The effect of various reaction parameters such as catalyst concentration, acid/alcohol molar ratio and reaction time was studied to optimize the conditions for maximum conversion of oleic acid. A detailed kinetic study was carried out and activation energies were determined from the Arrhenius plot. From the kinetic studies it was found that esterification of oleic acid follows first order kinetics with respect to substrate concentration. The activation energy was found to be 44.6 and 52.4 kJ mol− 1 for 12-tungstophosphoric acid anchored to SBA-15 and MCM-41, respectively. Based on the catalytic as well as kinetic studies, 12-tungstophosphoric acid anchored to SBA-15 was found to be a better catalyst.Display Omitted
Keywords: Esterification; Biodiesel; 12-Tungstophosphoric acid; MCM-41; SBA-15;