Octane Booster Research Articles

An engine-relevant kinetic investigation into the anti-knock effect of organometallics through the example of ferrocene

Abstract A detailed study on the ignition of ferrocene-containing mixtures has been undertaken in a Rapid Compression Machine (RCM). Two hydrocarbon fuels, isooctane and 3-hexene, were investigated in order to assess the hypothesis of an inhibiting effect of iron oxide particles on HO2 radicals and H2O2. Ignition delays were measured at core gas temperatures of 700 K and 850 K, pressures from 6 to 20 bar, and ferrocene mole fractions in the original fuel from 0 to 900 ppm. These experiments provide insight into the kinetics of the antiknock effect of ferrocene on both the non-octane sensitive (isooctane) and octane sensitive (3-hexene) fuels. Experimental results show that doping reactive mixtures with ferrocene always lengthens the total ignition delay. Also, the increment in auto-ignition delay is monotonic with increasing amount of ferrocene while no loss of effectiveness was noticed, even at the highest mole fractions. On the other hand, in the event of two stage ignition, the first stage delay is not affected by any doping with ferrocene. The kinetic mode of action of ferrocene is investigated, based on these statements, in an effort to better understand the impact of organometallic octane boosters on the combustion of fuels. A kinetic short sub-mechanism was built in order to describe the influence of ferrocene on the reactivity of isooctane and 3-hexene in a RCM, yielding qualitative agreement.

The combustion kinetics of the lignocellulosic biofuel, ethyl levulinate

Ethyl levulinate (Ethyl 4-oxopentanoate) is a liquid molecule at ambient temperature, comprising of ketone and ethyl ester functionalities and is one of the prominent liquid fuel candidates that may be easily obtained from lignocellulosic biomass. The combustion kinetics of ethyl levulinate have been investigated. Shock tube and rapid compression machine apparatuses are utilised to acquire gas phase ignition delay measurements of 0.5% ethyl levulinate/O2 mixtures at ϕ = 1.0 and ϕ = 0.5 at ∼ 10 atm over the temperature range 1000–1400 K. Ethyl levulinate is observed not to ignite at temperatures lower than ∼1040 K in the rapid compression machine. The shock tube and rapid compression machine data are closely consistent and show ethyl levulinate ignition delay to exhibit an Arrhenius dependence to temperature. These measurements are explained by the construction and analysis of a detailed chemical kinetic model. The kinetic model is completed by establishing thermochemical-kinetic analogies to 2-butanone, for the ethyl levulinate ketone functionality, and to ethyl propanoate for the ethyl ester functionality. The so constructed model is observed to describe the shock tube data very accurately, but computes the rapid compression machine data set to a lesser but still applicable fidelity. Analysis of the model suggests the autooxidation mechanism of ethyl levulinate to be entirely dominated by the propensity for the ethyl ester functionality to unimolecularly decompose to form levulinic acid and ethylene. The subsequent reaction kinetics of these species is shown to dictate the overall rate of the global combustion reaction. This model is then use to estimate the Research and Motored Octane Numbers of ethyl levulinate to be ≥97.7 and ≥ 93, respectively. With this analysis ethyl levulinate would be best suited as a gasoline fuel component, rather than as a diesel fuel as suggested in the literature. Indeed it may be considered to be useful as an octane booster. The ethyl levulinate kinetic model is constructed within a state-of-the-art gasoline surrogate combustion kinetic model and is thus available as a tool with which to investigate the use of ethyl levulinate as a gasoline additive.

2-Methylfuran: A bio-derived octane booster for spark-ignition engines

The efficiency of spark-ignition engines is limited by the phenomenon of knock, which is caused by auto-ignition of the fuel-air mixture ahead of the spark-initiated flame front. The resistance of a fuel to knock is quantified by its octane index; therefore, increasing the octane index of a spark-ignition engine fuel increases the efficiency of the respective engine. However, raising the octane index of gasoline increases the refining costs, as well as the energy consumption during production. The use of alternative fuels with synergistic blending effects presents an attractive option for improving octane index. In this work, the octane enhancing potential of 2-methylfuran (2-MF), a next-generation biofuel, has been examined and compared to other high-octane components (i.e., ethanol and toluene). A primary reference fuel with an octane index of 60 (PRF60) was chosen as the base fuel since it closely represents refinery naphtha streams, which are used as gasoline blend stocks. Initial screening of the fuels was done in an ignition quality tester (IQT). The PRF60/2-MF (80/20 v/v%) blend exhibited longer ignition delay times compared to PRF60/ethanol (80/20 v/v%) blend and PRF60/toluene (80/20 v/v%) blend, even though pure 2-MF is more reactive than both ethanol and toluene. The mixtures were also tested in a cooperative fuels research (CFR) engine under research octane number and motor octane number like conditions. The PRF60/2-MF blend again possesses a higher octane index than other blending components. A detailed chemical kinetic analysis was performed to understand the synergetic blending effect of 2-MF, using a well-validated PRF/2-MF kinetic model. Kinetic analysis revealed superior suppression of low-temperature chemistry with the addition of 2-MF. The results from simulations were further confirmed by homogeneous charge compression ignition engine experiments, which established its superior low-temperature heat release (LTHR) suppression compared to ethanol, resulting in better blending octane numbers. This work explores and provides a chemically sound explanation for the potential of 2-MF as an octane enhancer.

Esterification of glycerol with acetic acid over Lewatit catalyst

Tri Acetyl Glycerol or triacetin is one of the glycerol derivative products which can be used as additives in liquid fuels (octane boosters) to reduce knocking on the machine. The use of triacetin as octane booster is considered very promising because it comes from renewable and environmentally friendly raw materials. The resulting glycerol-based additives are suitable for gasoline, biodiesel and diesel. In this study glycerol esterification with acetic acid over Lewatit catalyst was investigated. The effects of various parameters, such as reaction temperature, weight of catalyst and molar ratio of glycerol to acetic acid were studied and the optimum condition for the triacetin synthesis are 100°C, 1: 7 mole of ratio and 3% weight of catalys

Performance and emissions of si engine with octane boosters

In today’s world we see that the demand for gasoline and cars keep increasing and one problem which is significantly seen is that we either opt for a fuel which provides higher performance or for a fuel which provides lesser emissions. In this study we aim to provide higher performance and lower emissions by combining two chemicals or octane boosters, namely ethanol and toluene with gasoline and find out its performance and emission characteristics when compared with traditional gasoline and ethanol-gasoline blend. In this study we have made four blends which are PP, E10, E10T5 and E20T5 which are tested against two performance parameters which are Specific Fuel Consumption, Brake Thermal Efficiency with respect to brake power and emissions parameter which are Carbon Dioxide, Carbon Monoxide, Oxides of Nitrogen and Hydrocarbon with respect to brake power as well. In each of these performance and emissions parameters, the blends are compared and we find that E20T5 has the highest performance and E10T5 has the lowest emission.

A review of furfural derivatives as promising octane boosters

Prospects for using furfural derivatives as octane boosters for gasoline are discussed on the basis of analysis of their physicochemical and operation properties. Knock resistance data, toxicity parameters, and results of motor bench tests are considered for furan compounds, furfural ethers, furfurylamine, and other furfural derivatives.

Investigation of gasoline containing GTL naphtha in a spark ignition engine at full load conditions

Gas-to-liquid (GTL) naphtha can be used as a gasoline blend component, and the challenge of its low octane rating is solved by using ethanol as an octane booster. However, currently there is little knowledge available about the performance of gasolines containing GTL naphtha in spark ignition engines. The objective of this work is to assess full load performance of gasoline fuels containing GTL naphtha in a modern spark ignition engine. In this study, four new gasoline fuels containing up to 23.5vol.% GTL naphtha, and a standard EN228 gasoline fuel (reference fuel) were tested. These new gasoline fuels all had similar octane rating with that of the standard EN228 gasoline fuel. The experiments were conducted in an AVL single cylinder spark ignition research engine under full load conditions in the engine speed range of 1000–4500rpm. Two modern engine configurations, a boosted direct injection (DI) and a port fuel injection (PFI), were used. A comprehensive thermodynamic analysis was carried out to correlate experiment data with fuel properties. The results show that, at the full load operating conditions the combustion characteristics and emissions of those gasoline fuels containing GTL naphtha were comparable to those of the standard EN228 gasoline fuel. Volumetric fuel consumption of fuels with high GTL naphtha content was higher due to the need of adding more ethanol to offset the reduced octane rating caused by GTL naphtha. Results also indicate that, compared to the conventional compliant E228 gasoline fuel, lower particulate emissions were observed in gasoline fuels containing up to 15.4vol.% GTL naphtha.

Etherification of Glycerol with Propylene or 1-Butene for Fuel Additives.

The etherification of glycerol with propylene over acidic heterogeneous catalysts, Amberlyst-15, S100, and S200 resins, produced mono-propyl glycerol ethers (MPGEs), 1,3-di- and 1,2-di-propyl glycerol ethers (DPGEs), and tri-propyl glycerol ether (TPGE). The propylation of glycerol over Amberlyst-15 yielded only TPGE. The glycerol etherification with 1-butene over Amberlyst-15 and S200 resins produced 1-mono-, 2-mono-, 1,2-di-, and 1,3-di-butyl glycerol ethers (1-MBGE, 2-MBGE, 1,2-DBGE, and 1,3-DBGE). The use of Amberlyst-15 resulted in the propylation and butylation of glycerol with higher yields than those obtained from the S100 and S200 resins. The PGEs, TPGE, and BGEs were evaluated as cold flow improvers and octane boosters. These alkyl glycerol ethers can reduce the cloud point of blended palm biodiesels with diesel. They can increase the research octane number and the motor octane number of gasoline.

Performances and Emissions Characteristics of Three Main Types Composition of Gasoline-Ethanol Blended in Spark Ignition Engines

Ethanol as an alternative fuel will become the prime feed of vehicles for replacing the fossil fuel in the future. It is due to the combustion of ethanol producing the lowest particulate and it could be renewed, respect to gasoline. Some properties of ethanol have several advantages when applied in engine spark ignition. It has high octane number, allowing to improve the compression ratio to minimize knocking and increasing torque and power as well. Furthermore, the high heat of vaporization reduces the peak of cylinder temperature so NOx radiation is overcast. Moreover, the oxygen content of ethanol helps to the stoichiometric combustion therefore CO and HC emissions are lower if compared to gasoline. This paper will explain the combustion characteristic of ethanol in spark ignition engine with port and direct injection system, even in carburettor system. The characteristic will describe when being run with three main composition of gasoline-ethanol blends; those are 0–20, 25–40 and 50–100% respectively. The result shows that ethanol will act as an octane booster when it is added in gasoline up to 20% (E20). The blends have some impact on improving engine performances and to reduce emissions without any adjustment on the engine. In concentration, 25 to 40% of ethanol needs to adjust a suitable compression ratio as an increasing of ethanol percentage. Finally, in high concentration setting simultaneously of CRs, ignition timing and excess air will be applied to produce high performances and low emissions.

Performance and emissions of gasoline blended with terpineol as an octane booster

This study investigates the effect of using terpineol as an octane booster for gasoline fuel. Unlike ethanol, terpineol is a high energy density biofuel that is unlikely to result in increased volumetric fuel consumption when used in engines. In this study, terpineol is added to non-oxygenated FACE F gasoline (Research Octane Number = 94.5) in volumetric proportions of 10%, 20% and 30% and tested in a single cylinder spark ignited engine. The performance of terpineol blended fuels are compared against a standard oxygenated EURO V (ethanol blended) gasoline. It was determined that the addition of terpineol to FACE F gasoline enhanced the octane number of the blend, resulting in improved brake thermal efficiency and total fuel consumption. For FACE F + 30% terpineol, break thermal efficiency was improved by 12.1% over FACE F gasoline at full load for maximum brake torque operating point, and similar performance as EURO V gasoline was achieved. Due to its high energy density, total fuel consumption was reduced by 6.2% and 9.7% with 30% terpineol in the blend when compared to FACE F gasoline at low and full load conditions, respectively. Gaseous emissions such as total hydrocarbon and carbon monoxide emission were reduced by 36.8% and 22.7% for FACE F + 30% terpineol compared to FACE F gasoline at full load condition. On the other hand, nitrogen oxide and soot emissions are increased for terpineol blended FACE F gasoline when compared to FACE F and EURO V gasoline.

Performance of lignin derived compounds as octane boosters

The performance of spark ignition engines is highly dependent on fuel anti-knock quality, which in turn is governed by autoignition chemistry. In this study, we explore this chemistry for various aromatic oxygenates (i.e., anisole, 4-methyl anisole, 4-propyl anisole, guaiacol, 4-methyl guaiacol, 4-ethyl guaiacol) that can be produced from lignin, a low value residual biomass stream that is generated in paper pulping and cellulosic ethanol plants. All compounds share the same benzene ring, but have distinct oxygen functionalities and degrees of alkylation. The objective of this study is to ascertain what the impact is of said side groups on anti-knock quality and, by proxy, on fuel economy in a modern Volvo T5 spark ignition engine. To better comprehend the variation in behavior amongst the fuels, further experiments have been conducted in a constant volume autoignition device. The results demonstrate that alkylation has a negligible impact on anti-knock quality, while the addition of functional oxygen groups manifests as a deterioration in anti-knock quality.

Conversion of Isobutylene to Octane-Booster Compounds after Methyltert-Butyl Ether Phaseout: The Role of Heterogeneous Catalysis

Over the last decades, the global demand of the production of methyl tert-butyl ether (MTBE) was significantly decreased from 30 million tons per year (MTPY) in 1995 to 12 million tons per year (MTPY) in 2011 because of the phaseout of MTBE in the United States and other countries. MTBE was banned in some countries because it produces health and environmental pollution and contaminates water and air quality. After MTBE phaseout, isobutylene feedstock is used for the production of another octane booster compound such as isooctane with a more environmental-friendly reputation. Isooctane is obtained by dimerization, trimerization, and oligomerization of isobutylene followed by a hydrogenation step. Dimerization of isobutylene to isooctane is a simple and low-cost-effective technology using heterogeneous catalysts such as zeolites, metal oxides, and resins. Zeolites are potential catalyst with high selectivity, high stability, easy regeneration, and low-cost production. The conversion and selectivity can be i...

Terpineol as a novel octane booster for extending the knock limit of gasoline

Improving the octane number of gasoline offers the potential of improved engine combustion, as it permits spark timing advancement without engine knock. This study proposes the use of terpineol as an octane booster for gasoline in a spark ignited (SI) engine. Terpineol is a bio-derived oxygenated fuel obtained from pine tree resin, and has the advantage of higher calorific value than ethanol. The ignition delay time (IDT) of terpineol was first investigated in an ignition quality tester (IQT). The IQT results demonstrated a long ignition delay of 24.7ms for terpineol and an estimated research octane number (RON) of 104, which was higher than commercial European (Euro V) gasoline. The octane boosting potential of terpineol was further investigated by blending it with a non-oxygenated gasoline (FACE F), which has a RON (94) lower than Euro V gasoline (RON=97). The operation of a gasoline direct injection (GDI) SI engine fueled with terpineol-blended FACE F gasoline enabled spark timing advancement and improved engine combustion. The knock intensity of FACE F+30% terpineol was lower than FACE F gasoline at both maximum brake torque (MBT) and knock limited spark advance (KLSA) operating points. Increasing proportions of terpineol in the blend caused peak heat release rate, in-cylinder pressure, CA50, and combustion duration to be closer to those of Euro V gasoline. Furthermore, FACE F+30% terpineol displayed improved combustion characteristics when compared to Euro V gasoline.

Evaluation of Freezing-Thawing Cycles for Foundation Soil Stabilization

Freezing-thawing cycles in soils reduce considerably the foundation capacity of buildings and infrastructure. In recent years, development of nontraditional stabilizers has created hundreds of new products for soil stabilization. Fiber portions of biomass (such as lignin) can be considered as byproducts of the conversion process, and these byproducts are generally used to produce octane booster fuels, bio-based products, and other chemical products. The use of lignin-based biofuel co-products (BCPs) to stabilize pavement subgrade soil is an innovative idea and satisfies the needs of sustainable development in construction. A series of laboratory tests, including unconsolidated undrained direct shear test, freeze-thaw durability test, and scanning electron microscope tests, was conducted to evaluate the effect of BCP addition on shear strength performance for four different soils encountered in Iowa. The results of this study indicate that BCPs are beneficial in the soil stabilization of low-quality materials for use in road construction.

Antiknock quality and ignition kinetics of 2-phenylethanol, a novel lignocellulosic octane booster

High-octane quality fuels are important for increasing spark ignition engine efficiency, but their production comes at a substantial economic and environmental cost. The possibility of producing high anti-knock quality gasoline by blending high-octane bio-derived components with low octane naphtha streams is attractive. 2-phenyl ethanol (2-PE), is one such potential candidate that can be derived from lignin, a biomass component made of interconnected aromatic groups. We first ascertained the blending anti-knock quality of 2-PE by studying the effect of spark advancement on knock for various blends 2-PE, toluene, and ethanol with naphtha in a cooperative fuels research engine. The blending octane quality of 2-PE indicated an anti-knock behavior similar or slightly greater than that of toluene, and ethylbenzene, which could be attributed to either chemical kinetics or charge cooling effects. To isolate chemical kinetic effects, a model for 2-PE auto-ignition was developed and validated using ignition delay times measured in a high-pressure shock tube. Simulated ignition delay times of 2-PE were also compared to those of traditional high-octane gasoline blending components to show that the gas phase reactivity of 2-PE is lower than ethanol, and comparable to toluene, and ethylbenzene at RON, and MON relevant conditions. The gas-phase reactivity of 2-PE is largely controlled by its aromatic ring, while the effect of the hydroxyl group is minimal. The higher blending octane quality of 2-PE compared to toluene, and ethylbenzene can be attributed primarily to the effect of the hydroxyl group on increasing heat of vaporization.

A shock tube study of C4–C6 straight chain alkenes + OH reactions

Alkenes are known to be good octane boosters and they are major components of commercial fuels. Detailed theoretical calculations and direct kinetic measurements of elementary reactions of alkenes with combustion radicals are scarce for C4 alkenes and they are practically absent for C5 and larger alkenes. The overall rate coefficients for the reaction of OH radical with 1-butene (CH2CHCH2CH3, kI), 1-pentene (CH2CHCH2CH2-CH3, kII), cis/trans 2-pentene (CH3CHCHCH2CH3, kIII and kIV), 1-hexene (CH2CHCH2CH2CH2CH3, kV) and cis/trans 2-hexene (CH3CHCHCH2CH2CH3, kVI and kVII) were measured behind reflected shock waves over the temperature range of 833–1377K and pressures near 1.5atm. The reaction progress was followed by measuring mole fraction of OH radicals near 306.7nm using UV laser absorption technique. It is found that the rate coefficients of OH+trans-2-alkenes are larger than those of OH+cis-2-alkenes, followed by OH+1-alkenes. The derived Arrhenius expressions for the overall rate coefficients (in cm3.mol−1.s−1) are:kI=(4.83±0.03)104.T2.72±0.01.exp(940.8±2.9cal/molRT)(946K−1256K)kII=(5.66±0.54)10−1.T4.14±0.80.exp(4334±227cal/molRT)(875K−1379K)kIII=(3.25±0.12)104.T2.76±0.5.exp(1962±83cal/molRT)(877K−1336K)kIV=(3.42±0.09)104.T2.76±0.5.exp(1995±59cal/molRT)(833K−1265K)kV=(7.65±0.58)10−4.T5±1.exp(5840±175cal/molRT)(836K−1387K)kVI=(2.58±0.06)106.T2.17±0.37.exp(1461±55cal/molRT)(891K−1357K)kVII=(3.08±0.05)106.T2.18±0.37.exp(1317±38cal/molRT)(881K−1377K)

A blending rule for octane numbers of PRFs and TPRFs with ethanol

Ethanol is widely used as an octane booster in commercial gasoline fuels. Its oxygenated nature aids in reducing harmful emissions such as nitric oxides (NOx), soot and unburned hydrocarbons (HC). However, the non-linear octane response of ethanol blending with gasoline fuels is not completely understood because of the unknown intermolecular interactions in such blends. In general, when ethanol is blended with gasoline, the Research Octane Number (RON) and the Motor Octane Number (MON) non-linearly increase (synergistic) or decrease (antagonistic), and the non-linearity depends on the composition of the base gasoline. The complexity of commercial gasoline, comprising of hundreds of different components, makes it challenging to understand ethanol–gasoline synergistic/antagonistic blending effects. Understanding ethanol blending effects with simpler gasoline surrogates blends may enable a better understanding of ethanol blending with complex multi-component gasoline fuels. This study presents a blending rule to predict the octane numbers (ON) of ethanol/primary reference fuel (PRF; mixtures of iso-octane and n-heptane) and ethanol/toluene primary reference fuel (TPRF; mixtures of toluene, iso-octane and n-heptane) mixtures using the data available in literature and new data. The ON of ethanol blends with PRF-40, -50, and -60 were measured and compared with those from literature. Additional experimental data were collected to validate the developed model for ethanol blends of three different TPRFs having the same RON but different MON (i.e., different toluene contents). The three tested TPRF mixtures have octane ratings of RON 60.0/MON 58.0 (toluene 10.2vol%), RON 60.0/MON 56.3 (toluene 19.8vol%), and RON 60.0/MON 53.2 (toluene 40.2vol%). The octane prediction model consists of linear and non-linear by mole regions. The transition point between the linear and non-linear regions is a function of the RON and MON of the base PRF and TPRF mixture. The non-linear by mole region is defined as a second-order polynomial and the combined model successfully predicts the octane number (ON) of the various ethanol/PRF and ethanol/TPRF blends with a maximum ON error of 2.7, with the majority of predictions being within the reproducibility limits. Finally, the model presented here is shown to be an improvement over that existing already in the literature.

Experimental study on deep desulfurization of MTBE by electrochemical oxidation and distillation

With the increasing awareness of environmental protection, deep desulfurization of methyl tert-butyl ether (MTBE), which is the most important octane booster in gasoline, is extremely urgent.

Exposure to methyl tert-butyl ether (MTBE) is associated with mitochondrial dysfunction in rat

1. Methyl tert-butyl ether (MTBE) is commonly used as an octane booster and oxygenate additive to gasoline. The assumed toxic effects of MTBE on human health are a matter of great debate. Exposure to MTBE has been shown to induce oxidative damage and no mechanistic explanation is available so far. Our goals were to determine whether MTBE is a mitochondrial toxicant, if so, what mechanism(s) is involved.2. Male Sprague-Dawley rats were received MTBE in drinking water for 3 months. At the end of treatments, animals were killed, liver and blood samples were collected for biochemical and histopathological studies, and oxidative stress biomarkers. The rat liver mitochondria were isolated and several mitochondrial indices were measured.3. We found that zinc plasma levels were remarkably declined with MTBE and N, N, N′, N′-Tetrakis (2-pyridylmethyl) ethylenediamine (TPEN; a zinc chelator) exposure. MTBE induced oxidative damage and caused mitochondrial dysfunctions in rats. Supplementation with zinc was able to protect against MTBE-induced cellular and sub-cellular toxicity.4. Our results demonstrated that long-term exposure to MTBE is associated with zinc deficiency, oxidative stress, and mitochondrial energy failure in rat.

Mixed butanols addition to gasoline surrogates: Shock tube ignition delay time measurements and chemical kinetic modeling

The demand for fuels with high anti-knock quality has historically been rising, and will continue to increase with the development of downsized and turbocharged spark-ignition engines. Butanol isomers, such as 2-butanol and tert-butanol, have high octane ratings (RON of 105 and 107, respectively), and thus mixed butanols (68.8% by volume of 2-butanol and 31.2% by volume of tert-butanol) can be added to the conventional petroleum-derived gasoline fuels to improve octane performance. In the present work, the effect of mixed butanols addition to gasoline surrogates has been investigated in a high-pressure shock tube facility. The ignition delay times of mixed butanols stoichiometric mixtures were measured at 20 and 40 bar over a temperature range of 800–1200 K. Next, 10 vol% and 20 vol% of mixed butanols (MB) were blended with two different toluene/n-heptane/iso-octane (TPRF) fuel blends having octane ratings of RON 90/MON 81.7 and RON 84.6/MON 79.3. These MB/TPRF mixtures were investigated in the shock tube conditions similar to those mentioned above. A chemical kinetic model was developed to simulate the low- and high-temperature oxidation of mixed butanols and MB/TPRF blends. The proposed model is in good agreement with the experimental data with some deviations at low temperatures. The effect of mixed butanols addition to TPRFs is marginal when examining the ignition delay times at high temperatures. However, when extended to lower temperatures (T < 850 K), the model shows that the mixed butanols addition to TPRFs causes the ignition delay times to increase and hence behaves like an octane booster at engine-like conditions.