Cetane number determination of synthetic diesel fuels

doi:10.1016/0016-2361(92)90061-R

Fuel

Volume 71, Issue 11, November 1992, Pages 1323-1327

https://doi.org/10.1016/0016-2361(92)90061-R Get rights and content

Abstract

Equations are proposed for predicting the cetane number of hydrogenated diesel fuel derived from the catalytic oligomerization of low-chain-length alkenes. The cetane number is a function of the relative amounts of CH₃ and CH₂ type protons present in the fuel as determined from ¹H n.m.r. data. The predictive equations are specific to those used for synthetic fuels and are shown to be superior to those proposed previously.

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Cited by (36)

Optimization of continuous-flow heterogeneous catalytic oligomerization of 1-butene by design of experiments and response surface methodology
2020, Fuel
Citation Excerpt :
According to the literature, these may include co-oligomerization (involving olefins with an odd number of carbon atoms), isomerization (double bond or alkyl group shifts), dehydrogenation, hydrogen transfer, cracking (e.g., carbenium ion/bimolecular catalytic cracking involving β-scission; protolytic cracking), cyclization and dehydrocyclization (aromatization), Scheme 1 [10,69–73]. The cetane number (CN) and isoparaffinic index (I) of the product mixtures were determined by 1H NMR spectroscopy, based on the O'Connor method (details in Supplementary Material section, Table S1) [74]. This technique was also used to determine the total aromatics content (%Ar), for comparison to the results of GC×GC-ToFMS.
Oligomerization of light olefins allows the production of clean, sulphur-free fuels or fuel additives with reduced aromatics content, and useful chemicals. Commercial heterogeneous catalytic oligomerization technologies were developed to meet market demands in flexible fashions, whereby the operating conditions may be adjusted in favor of the desired product specifications and yields. For achieving superior performances, the development of expeditious evaluation and optimization tools is important, albeit not trivial because light olefins oligomerization involves complex reaction systems and product quality depends on many factors. In this sense, the design of experiments (DoE) and response surface methodology (RSM) are valuable tools, yet unexploited for light olefins oligomerization processes. In this work, DoE/RSM models were developed and validated for the oligomerization of 1-butene – derivable from fossil or renewable sources of organic carbon – over a superior hierarchical zeotype catalyst, under high pressure, continuous flow conditions, targeting clean diesel range products. The models allowed to investigate the individual and cross effects of reaction pressure, temperature and weight hourly space velocity on conversion and yields of specific product fractions. The optimization studies also accounted for product quality features such as, reduced aromatics content; these studies counted with the analytical input of Comprehensive Two-Dimensional Gas Chromatography with Time-of-Flight Mass Spectrometry (GC×GC-ToFMS) for characterizing the products. Importantly, DoE/RSM tools may contemplate not only kinetic data, but also product quality indicators, and help identify most relevant process parameters impacting on the productivity.
Olefin oligomerisation over nanocrystalline MFI-based micro/mesoporous zeotypes synthesised via bottom-up approaches
2019, Renewable Energy
Citation Excerpt :
The low aromatics content and the absence of heteroatoms are advantages of light olefin oligomerisation routes for synthesising clean fuels. The I values were in the range 0.47–0.59, based on the O'Connor or Kapur methods [65,66]. These results are advantageously lower than that reported in the literature for a mesostructured zeotype based on the BEA topology (I ≈ 0.62) [57], tested under similar 1C4 reaction conditions.
The oligomerisation of 1-butene was studied under high-pressure continuous-flow conditions (200–250 °C, 30–40 bar), in the presence of micro/mesoporous zeotypes based on the MFI topology, which were prepared via different non-destructive bottom-up strategies: crystallization of silanized protozeolitic units; co-templating with a dual function (polymeric) template; and using a sole structure directing agent (non-surfactant and non-polymeric) to generate mesoporosity. The synthesis method influenced the material properties and consequently the catalytic performance. In targeting hydrocarbons with boiling point ranges characteristics of diesel, the zeotypes benefited from regular morphology, reduced crystallite size, mesoporosity and enhanced molar ratio of Lewis (L) to Brønsted (B) acid sites (L/B). In general, the zeotypes outperformed commercial zeolite ZSM-5. The best-performing zeotype was prepared according to the Serrano strategy based on the crystallization of silanized zeolitic seeds, and led to 97% conversion and an average space-time yield of liquid products of 1077 mg g_cat⁻¹ h⁻¹, at 250 °C, 40 bar. The zeotypes seemed more stable than the commercial zeolite, based on molecular level characterization studies of the used/regenerated catalysts, with some differences in catalytic activity.
Impact of nitric oxide on n-heptane and n-dodecane autoignition in a new high-pressure and high-temperature chamber
2019, Proceedings of the Combustion Institute
A New One Shot Engine (NOSE) was designed to simulate the thermodynamic conditions at High Pressure-High Temperature like an actual common-rail diesel engine in order to study the compression ignition of spray. The volume of the combustion chamber provided with large optical windows simplified the implementation of various optical diagnostics. The advantage of this kind of set-up in comparison to pre-burn or flue chambers is that the initial gas mixture can be well controlled in terms of species and mole fraction. The purpose of this work was to investigate the impact of nitric oxide (NO) on ignition delay (ID) for two fuels with different cetane numbers: n-heptane, and n-dodecane. In the thermodynamic conditions chosen (60 bar and over 800–900 K), NO had a strong effect on ID, with increases in NO tending to reduce the ignition delay. Results showed that ID and Lift-Off Length (LOL) presented the same trend as a function of temperature and NO concentration. Experimentally, at 900 K the ignition of n-dodecane was promoted by NO up to 100 ppm, whilst higher NO levels did not further promote ignition and a stabilization of the value has been noticed. For n-heptane, stronger promoting effects were observed in the same temperature conditions: the ignition delays were monotonically reduced with up to 200 ppm NO addition. At a lower temperature (800 K) the inhibiting effect was observed for n-dodecane for [NO] greater than 40 ppm, whereas only a promoting effect was observed for n-heptane. The experimental results of LOL showed that NO shortened LOL in almost all cases, and this varied with both the NO concentration and the mixture temperature. Thus, fuels with shorter ignition delays produce shorter lift-off lengths.
TUD-1 type aluminosilicate acid catalysts for 1-butene oligomerisation
2017, Fuel
Citation Excerpt :
The O’Connor correlation gave CN = 62 for GDiesel, which is higher than the values obtained using test engines, albeit not drastically different. The difference may be partly due to the fact that the O’Connor correlation gives better predictions for synthetic fuels produced via oligomerisation of light olefins, than for crude-oil-based diesel which contains relatively high amounts of aromatics (the GDiesel produced by Galp Energia refinery contained 23% aromatics) [49]. To gain insights into the types of chemical compounds formed, the mixture of reaction products for Al-TUD-1(25) as catalyst, under typical conditions, was analysed by GC × GC–ToFMS.
TUD-1 type mesoporous aluminosilicates were explored for the acid-catalysed oligomerisation of 1-butene, under high pressure, continuous flow operation, which is an attractive route to produce sulphur-free synthetic fuels with reduced aromatics content. The solid acid catalysts were synthesised via one-pot synthesis (HT) or stepwise approach (PG), without using surfactants as templates, which is an eco-friendly characteristic of the TUD-1 family. While the HT approach may be advantageous in terms of process intensification in relation to the PG one, the latter may lead to relatively low molar ratios Si/Al. The catalysts possessed Si/Al ratios in the range 3–5 and 17–35 for the PG and HT approaches, respectively, pore sizes in the range 10–14 nm, and essentially Lewis acidity. To the best of our knowledge, this is the first report of siliceous oxide TUD-1 furnished with acidity via post-synthesis grafting (PG) of Al-species. For comparative studies, an ordered mesoporous aluminosilicate was synthesised via the PG approach using surfactant mixtures. All materials prepared promoted the reaction of 1-butene to higher molar mass products. The best-performing catalyst in terms of space-time yields of the 170–390 °C cut (boiling point range) products (of the type middle distillates) was Al-TUD-1(25)-HT synthesised via the HT method. The products were analysed by comprehensive two-dimensional gas chromatography (GC × GC) combined with time-of-flight mass spectrometry (ToFMS). The influence of material properties and process parameters on the catalytic reaction, and catalyst stability were studied. The catalytic performances were benchmarked with ZSM-5 (zeolite used in commercial oligomerisation processes).
Chemical kinetic and combustion characteristics of transportation fuels
2015, Proceedings of the Combustion Institute
Citation Excerpt :
Each parameter can be determined directly by one or more approved experimental test procedures or by correlations among measured parameters, for example, the cetane index (CI) [71]. Alternative fuels and their blends with petroleum based fuels may not fall within the petroleum history represented by these correlations [72]. Engine/fuel interactions for a specific IC engine are typically expressed in terms of application target data (for example, autoignition, burning rates, cylinder pressure history, pre-ignition, engine knock, super knock, specific fuel consumption, emissions, etc. for piston engines [60]; flash back, flame volume, flame stability, radiative loading, lean blow-out, re-light, emissions, etc. for gas turbines) that relate to specific engine design/operating conditions and fuel chemical/physical reference indicators.
Internal combustion engines running on liquid fuels will remain the dominant prime movers for road and air transportation for decades, probably for most of this century. The world’s appetite for liquid transportation fuels derived from petroleum and other fossil resources is already immense, will grow, will at some future time become economically unsustainable, and will become infeasible only in the very long term. The ongoing process of augmenting and eventually replacing petroleum-derived fuels with liquid alternative fuels must necessarily involve approaches that result in comparatively much lower net carbon cycle emissions from the transportation sector, most likely through a combination of carbon sequestration and renewable fuel production. The successful growth and establishment of a sustainable, profitable alternative fuels industry will be best facilitated by approaches that integrate alternative products into petroleum-derived fuel streams (i.e., gasolines, diesel, and jet fuels) and consider synergistic evolution of and integration with prevailing refining and liquid fuel distribution infrastructures.
The emergence of low temperature combustion strategies, particularly those implementing dual fuel methods to achieve Reaction Controlled Compression Ignition (RCCI), offers the potential to significantly improve operating efficiency and reduce emissions with minimal aftertreatment. For all advanced combustion engine technologies, but especially for RCCI, a clear understanding of fuel property influences on combustion behaviors will be important to achieving projected engine performance and emissions.
To achieve the benefits projected by emerging engine technologies, the properties of petroleum-derived fuels themselves must be modified over time, but the effects of blending candidate alternative fuels with these conventional fuels must also be understood. Predicting the coupled physical and chemical property effects of real fuels on energy conversion system performance and emissions is a daunting problem, even for petroleum-derived real fuels, since each is composed of several hundred to thousands of individual chemical species typically belonging to one of a few organic classes (e.g., n-paraffins, iso-paraffins, cyclo-paraffins, olefins, aromatics). For specific combustion applications, it is often the global combustion response to variations in the composition of fuel mixtures – inclusive of those occurring by blending petroleum-derived fuel with alternative fuel candidates – that is of interest for fuel property optimization. This paper presents an overview of tools used for evaluating and emulating combustion-relevant properties of real fuels and alternative fuel candidates. New analytical and statistical methods can provide important insights as to how the ensembles of distinct molecular structures found in a given fuel mixture contribute to the physical and chemical kinetic properties that govern its combustion in energy conversion processes. Such tools can in turn assist in screening candidate alternative fuels for more detailed study.
Study of combustion process of biodiesel/gasoil mixture in a domestic heating boiler of 26.7kW
2014, Biomass and Bioenergy
This study is focused on the use of biodiesel in a liquid fuel heating boiler of 26.7 kW. The influence of biodiesel/diesel mixtures, air flow rate, and input pressure on a combustion process for heating purposes was analyzed. The study is divided into two parts. The first one deals with the characteristics of biodiesel as a heating fuel and the analysis of its properties and preparation method. The biodiesel was produced from sunflower oil in a pilot plant of 250 L/charge and was characterized according to standard norms. It was found that biodiesel is not acceptable as fuel for internal combustion engines (ester content of 92%). The second one deals with the effect of the operating variables on the combustion parameters in the boiler. The tests were conducted on experimental facilities and the generated emissions were analyzed. It was found that increasing the input burner pressure involves a decrease in CO and O₂ and an increase of CO₂ in the fumes, as well as an increase in the combustion process yield. Likewise, a greater air flow rate gives rise to a decrease in the latter parameter. Moreover, CO emissions were slightly higher when biodiesel content was increased in the mixture, and therefore the combustion yield decreased.

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Full paperCetane number determination of synthetic diesel fuels

Abstract

Am. Eng.

Eng.

Power Plant Eng.

Fuel

J. Inst. Pet.

J. Inst. Pet.

J. Chem. Soc.

Ind. Eng. Chem.

Hydrocarbon Process.

Energy & Fuels

Energy & Fuels

Full paper
Cetane number determination of synthetic diesel fuels