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1. Introduction

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aldehydes in the reaction products. The products obtained in the

nied by heightening of cloud point from 38 to +8 C.

Fuel Processing Technology 90 (2009) 686691

Contents lists available at ScienceDirect

Fuel Processing

e lsAccording to Djega-Mariadassou et al. (patent information) [1], thehydrogenating process of vegetable oils should be carried out underhydrogen partial pressure at least equal to 12 MPa in the presence ofhydrogenating catalyst and at the temperature higher than 350 C.

Stumborg et al. [2] informed that the main products of suchprocess are straight-chain parafn hydrocarbon fractions in dieselboiling range with cetane number between 55 and 90. Due to the very

Similarly, addition of 8 wt.% of this cetane improver to renerydiesel fraction, can increase cetane number from 43.6 to 47.7 andcloud point from 29 to +6 C. According to Stumborg et al. [2],addition of the vegetable diesel fraction as cetane improver has avast impact on carbon monoxide and total hydrocarbon emission inexhaust gases: a reduction of 69 and 63%, respectively, and relativelysmall impact on NOx emission (4% emission reduction).high cetane number they called that produhydroprocessing by-products were also obtahydrocarbons, some quantity of water and capartial hydrogenation can lead to obtain certa

Corresponding author. Tel.: +48 71 320 35 51; fax:E-mail address: jerzy.walendziewski@pwr.wroc.pl (J

0378-3820/$ see front matter 2008 Elsevier B.V. Adoi:10.1016/j.fuproc.2008.12.006genation of double andin of fatty acids. There is

number of highly aromatic (44.5 wt.%) fraction from 31.7 to 43.3.Unfortunately, the spectacular cetane number increase is accompa-ester bonds and splitting of linear carbon chaThere is also possibility to submit vegetable oils directly to hydro-processing resulting in partial or total hydroThermal or catalytic cracking ohydroprocessing can be an alternatiproduction. There are many advantagfuels production in comparison toenumerate some examples like the posfuels similar to diesel fuel of naphthaby-product waste utilization and the lcan be considered as waste free and envery important advantage in the wahod in renewable fuelsch approach to the bio-esterication. We canto produce hydrocarbonthe opportunity to avoidlycerol. This technologyental friendly and it is aegetable oil processing.

improve cetane number. Other properties of vegetable dieselfractions, such as viscosity and density, are similar to the commercialdiesel fuels.

As a result of heightened content of saturated parafn hydrocarbons,a relatively high pour and cloud points (low temperature properties) isthe main disadvantage of the vegetable diesel fraction. Therefore, itshould rather be not used as a component of winter diesel fuels.

It is necessary to point out that the vegetable diesel fractionsproduced by hydroprocessing can be used as cetane number improver.The addition of 20 wt.% of cetane number improver increases cetaneprocess are miscible with diesel fuel in all the proportions and linearlyHydroprocesssing of light gas oil rape o

Jerzy Walendziewski , Marek Stolarski, Rafa uny,Faculty of Chemistry, Wrocaw University of Technology, ul. Gdaska 7/9, 50-310 Wrocaw

a b s t r a c ta r t i c l e i n f o

Article history:Received 16 June 2008Received in revised form 5 December 2008Accepted 12 December 2008

Keywords:Gas oilVegetable oilsHydroprocessingDiesel fuelPropertiesCatalyst

Two series of experiments ofeed was composed of raw m20 wt.% rape oil and 80 wt.Hydroprocessing of both mi380 C), hydrogen pressurethat within limited range itfraction (diesel oil boiling raester bonds and hydrogenatphysicochemical properties

j ourna l homepage: www.ct super cetane. Someined, such as C1C4 lightrbon dioxide. Fatty acidsin quantity of alcohols or

+48 71 322 15 80.. Walendziewski).

ll rights reserved.l mixtures

rtomiej Klimekland

droprocessing of light gas oil - rape oil mixtures were carried out. The reactorerial: rst series 10 wt.% rape oil and 90 wt.% of diesel oil; second series f diesel oil.res was performed with the same parameter sets, temperature (320, 350 andd 5 MPa, LHSV=2 h1 and hydrogen feed ratio of 500 Nm3/m3. It was statedossible to control vegetable oil hydrogenolysis in the presence of light gas oile) through the proper selection of the process parameters. Hydrogenolysis ofof olenic bonds in vegetable oils are the main reactions in the process. Basicthe obtained hydroprocessed products are presented.

2008 Elsevier B.V. All rights reserved.

Technology

ev ie r.com/ locate / fuprocThe common hydroprocessing of naphtha derived diesel fuelfractionswith 10 to 30% vegetable oil addition is the third possibility ofvegetable oil application in fuel production. In this case deephydrodesulphurization of diesel fuel should be accompanied byhydrogenation of unsaturated fatty acid components and hydrogeno-lysis of ester bonds.

This paper presents the results of hydroprocessingof 10 and20wt.%of rape oil and 90 and 80 wt.% of light gas oil fraction mixtures in

continuous ow pressure apparatus. Process parameters were chan-ged in the following range: temperature 320380 C and hydrogenpressure 35 MPa. In order to obtain hydrogenolysis of more than 95%ester bonds and hydrogenation of double bonds with 10% of rape oilcontent in the feed, very strong process parameters are necessary, suchas temperature at least 350 C and hydrogen pressure 5 MPa.

The hydroprocessing of such feeds presents two undesiredphenomena. Firstly, parafn hydrocarbons obtained in the result ofhydrogenation of fatty acids lead to the increase in product meltingtemperature. This inuences further undesirable increase in cloud andmelting points as well as cold lter plugging point (CFPP) determinedfor the hydrorened products. Secondly, some feed hydrocracking isoccurring and we observe lowering of obtained products ash point.

2. Experimental

Two series of hydrorening experiments were carried out. The rstone used raw material 10 wt.% rape oil mixed with 90 wt.% of diesel

oil. The second one used raw material 20 wt.% rape oil mixed with80 wt.% of diesel oil.

Each experiment series was composed of four tests at differentprocess parameters (Table 1). A commercial hydroreninghydro-craking (NiMo/Al2O3) catalyst was used in the studies.

50 cm3 of NiMo catalyst was packed to the reactor tube (totalreactor volume 300 cm3). The catalyst was sulded with diethylsulde, S(C2H5)2 solution in diesel fuel before hydrorening testswere carried out. The experiments were realized in the laboratorycontinuous ow apparatus presented in Fig. 1. A membrane pump (2)supplied the oil feed mixture from the feed tank (3) to the catalyticreactor (4) (100 cm3/h). Hydrogen, 50 dm3/h i.e. 500 dm3/1 dm3 ofthe feed was fed to the reactor by the second inlet port. Catalyst bedtemperature was controlled and registered by three thermocouples.Hydrogen pressure in the hydrorening apparatus was stabilizedusing inletoutlet control gas valves and hydrogen manometers whilereactor and catalyst bed temperatureswere controlled by temperaturecontrollers (5). The gasliquid reaction mixture was owing out fromthe reactor to the water cooler (6) and then to the pressure gasliquidseparator (7) in order to separate gaseous fraction (hydrogen andsmall quantity of light hydrocarbons) from hydrorened oil mixture.Hydrogen containing gaseous products was released to atmosphere bygasmeter (1) while liquid hydrorening product was drained to theatmospheric separator (8) in order to remove the trace quantities ofgases. Afterwards it was submitted to the analysis.

The activity of the catalyst was stabilized in hydrodesulphurizationprocess of light gas oil (diesel fuel) for about 120 h before thehydrorening studies. The single hydrorening experiment lasted 8 hafter stabilization of process parameters, i.e. reactor hydrogenpressure and temperature as well as raw material and hydrogenows. Two product samples were taken from each experimental test.

Table 1Hydroprocessing parameters.

Series/exp. no. Temperature C Hydrogen pressure,MPa

LHSV, h1 H2/feed(Nm3/m3)

I/1 320 5 2 500I/3 350 5 2 500I/5 380 5 2 500I/7 350 3 2 500II/2 320 5 2 500II/4 350 5 2 500II/6 380 5 2 500II/8 350 3 2 500

687J. Walendziewski et al. / Fuel Processing Technology 90 (2009) 686691Fig. 1. Schematic view of hydrorening apparatus.

2.1. Product analysis

Hydrorening products contained small quantities of water andsuspended white products, waxy parafns. Water was removed byltration using anhydrous sodium sulfate and parafn crystals bydecantation.

The following analyses of the obtained product were carried outaccording to the suitable standards:

Product density (15 C) was determined using aerometer, accordingto EN ISO 3675, EN ISO 12185,

Kinematical viscosity (40 C) was determined using Ubbelohdeviscosimeter, according to EN ISO 3104,

Fractional composition, according to EN ISO 3405 method, Flash point was determined in PenskyMartens-closed cup, accord-ing to EN ISO 2719,

Cold lter plugging point (CFPP), according to EN 116, Bromine number was determined by potentiometer titrationaccording to PN-68/C-04520,

Total acid number (TAN) was determined by titration of the samplewith KOH solution, according to PN 85/C-04066,

Contents of ester bonds, aromatic compounds and carboxylic groupsin hydrorened products were determined by FTIR method.

3. Results and discussion

Results of therst series of hydroprocessing products are presentedin Table 2 while the results of the second series in Table 3. Table 4

severe process parameters brings as the outcome hydrogenation ofunsaturated and esters bonds. One can detect also products of partialand total glycerol hydrogenation (propane) as well as products ofhydrocracking of long chain hydrocarbons in the feed. Small quantityof light hydrocarbons in hydrorened products resulted in lowering ofinitial boiling points and temperatures of distillation of 10, 50 and90 vol.%.

In case of the hydrorened products, almost the whole productvolume (9998%) was distilled at the end boiling point although only9193 vol.% of the used feeds distilled at this point. It means that almostall the amount of vegetable oils in the reactor feed was transformed

Table 3Properties of the hydrorening products of the second experimental series.

Feed, 20 wt.%rape oil

Sample no., parameters

No. 2 No. 4 No. 6 No. 8

320 C,5 MPa, H2

350 C,5 MPa, H2

380 C,5 MPa, H2

350 C3 MPa, H2

Liquid product yield,wt.%

96 95 94 95

Viscosity at 40 C,[mm2/s]

4.38 3.74 3.06 2.86 3.24

Density 15 C[kg/m3]

854.5 842.4 832.9 830.5 836.0

DistillationInitial boilingpoint [C]

187 180 165 155 184

10% [C] 220 218 213 208 217

Table 4The selected quality requirements for diesel fuel, vegetable oil and methyl ester of rapeoil.

Vegetable oil FAME Diesel fuel

Min. Max. Min. Max. Min. Max.

Density at 15 C [kg/m3] 830 930 ~885 820 845Kinematics viscosity, 40 C mm2/s] 80 4.3 5,3 2 4.5Heating value [MJ/kg] 37.4 37 39 42.8 Ignition point [C] 285 ~200 65 Cetane number ~39 ~55 51 CFPP [C] +15 ~10 20 +5Sulfur content [mg/kg] ~10 50Water content [mg/kg] 1000 500 200Fractional distillation Initial boiling point, IBP [C] ~210 ~320 176 Temp. of 50 vol.% distillation ~340 ~350 290

688 J. Walendziewski et al. / Fuel Processing Technology 90 (2009) 686691presents comparison among physicochemical properties of diesel oil,rape oil and fatty acid methyl ester produced from rape oil.

3.1. Product yields

The preparation of the correct material balance for the laboratorystudies is a very difcult assignment. Tables 2 and 3 present the data ofthe obtained product yields after receiving them directly from theseparator. It is visible that ca 95 wt.% yield of hydrorened products canbe obtained. In larger process scale, i.e. industrial plant, higher liquid

Table 2Properties of the hydrorening products of the rst experimental series.

Reactor feed 10wt.% rape oil

Sample no., parameters

No. 1 No. 3 No. 5 No. 7

320 C,5 MPa, H2

350 C,5 MPa, H2

380 C,5 MPa, H2

350 C3 MPa, H2

Liquid productyield, wt.%

97 95 95 95

Viscosity at 40 C[mm2/s]

3.48 2.97 2.94 2.86 2.93

Density at 15 C[kg/m3]

846,4 836.5 834.7 834.6 835.8

DistillationInitial boilingpoint [C]

169 161 167 140 158

10% [C] 212 213 212 211 21250% [C] 279 275 280 277 27690% [C] 309 329 329 327 327250 C [vol.%] 33 32 31 31 32350 C [vol.%] 92 97 98.5 98.5 98.5

End boiling point[C]

341 345 348 353 340

% distilled fraction 93 96.5 98.5 99 98Flash point [C] 70 58 64 53 62(CFPP) [C] 25 9 17 14 13.5Bromine number[g Br2/100 g]

8.9 1.7 0.79 0.96 1.8

Acid number,[mg KOH/g]

0.51 0.60 0.48 0.58 0.89products yields should be achieved. As a result of hydrocrackingreactions, the purge gas fraction owing from the plant condensation/separator system contained about 5wt.% of gaseous light hydrocarbons.

3.2. Fractional compositions and ash points

Due to the high boiling temperature of rape oil, its addition todiesel fuels results mainly in some changes in end boiling point, i.e.lowering of the volume percent of distilled fuel fractions attemperature 350 C (Tables 2 and 3). The application of the relatively

50% [C] 287 286 279 277 28890% [C] 287 286 279 277 288250 C [vol.%] 28 28 31 33 31350 C [vol.%] 87 95 97 98 98

End boiling point [C] 353 360 358 363 348% distilled fraction 91 98 98 100 98Flash point [C] 70 38 37 37 38CFPP [C] 24 +4.3 0 +1.8 2.3Bromine number[g Br2/100 g]

15 8.43 3.8 2.05 4.9

Acid number,[mg KOH/g]

0.96 1.74 1.33 1.24 2.21

(hydrocracked) to lower temperature boiling hydrocarbons. It isnecessary to point out that distillation volumes and temperaturerange data of both the obtained hydrorened products and thecommercial diesel fuels are very close.

The lowering of ash points of the hydrocracked products wascaused by the light hydrocarbon molecules contained in the obtainedsamples, which resulted from partial hydrocracking. It is especiallynoticeable for the feed containing hydrorening products of 20-wt.%rape oil. Improvement of the product properties, heightening of theash point, is possible by product stabilization through the separationof low boiling hydrocarbons from the product by distillation.

3.3. Density

Thedensity of theused rape oil (890kg/m3) is higher thandensity ofdiesel oil (835 kg/m3) due to the fatty linear acids and oxygen content.Therefore densities of the obtained feeds are: the 10% rape oil of 847 kg/m3, while the 20% rape oil achieved value of 854 kg/m3 (Fig. 2).

As the result of the hydrocracking process, densities of theobtained products distinctly decreased. The simple dependence wasstated: the more severe the process parameters and higher rape oilconversion levels, the lower densities of the obtained products. It is aresult of vegetable oil hydrocracking presumably followed byisomerization of the obtained hydrocarbons. Densities of all the fuelsamples, including feeds were conformed to the standardized

containing feed were characterized by higher quantity of saturatedlinear hydrocarbons (parafns) and therefore their CFPP was higherthan 0 C but lower than 5 C. It means that all the products from both

689J. Walendziewski et al. / Fuel Processing Technology 90 (2009) 686691requirements specied for diesel fuels, i.e. standard density range820860 kg/m3 Table 4.

3.4. Kinematics viscosity

Kinematical viscosity of rape oil (78mm2/s) ismuch higher than ofdiesel oil (2.9 mm2/s, max. 4.5mm2/s, Table 4) and 10 or 20% additionof rape oil to diesel oil resulted in viscosity increase (Fig. 3). However,hydrorening of both feeds at process parameters, temperature 350 Cand 5 MPa or 350 C and 3 MPa made possible to lower viscosity to ca3 mm2/s. That phenomenon is explained by hydrocracking oftriglycerides molecules and lowering of average molecule weight inthe reaction mixtures in comparison to the processed feeds. Largevegetable oil molecules were converted to considerable smallermolecules of gasoline and gas oil. Similarly, as in the case of density,Fig. 2. Inuence of process parameters on density of the hydroprocessed products.viscosities of all the fuel samples, including feeds, were conformed tostandardized requirements, i.e. standard viscosity range 24.5 m2/sTable 4. One can observe only small inuence of rape oil content in thefeed on the viscosity of the hydrorened products.

3.5. CFPP (cold lter plugging point)

CFPP (cold lter plugging point) is a direct content function of highmelting point parafn hydrocarbons in the studied hydroreningproducts. The higher the parafn content in oil fraction, the higher isthe melting point (as well as crystallization and pour points) of thefuel. The addition of rape oil, with relatively low melting point, todiesel oil fraction does not inuence distinctly its CFPP (Fig. 4).

CFPP increase from lower than 20 C up to 4 C was due to thepartial hydrogenation of ester bonds and unsaturated bonds in fatty acidchains without hydrocracking. The results were obtained in hydroren-ing process of 20-wt.% rape oil containing feed at 320 C and pressure5 MPa. Such distinct increase in CFPP is an outcome of relatively rapidhydrogenation rate of olen bonds and hydrogenation of double bondsin fattyacids in oil triglycerides in the lowhydroprocessing temperature.The application of higher process temperature (350 C) and pressure (3and 5 MPa) led also to partial hydrocracking of oil molecules of highcrystallization point and enabled to obtain products with CFFP lowerthan10 C for the 10 wt.% rape oil containing feed.

All hydrorening products acquired by the use of 20 wt.% rape oil

Fig. 3. Inuence of process parameters on viscosity of the hydroprocessed products.Fig. 4. Inuence of process parameters on CFPP of the hydroprocessed products.

experimental series cannot be applied to diesel fuels blending inwinter season in most of the European countries Table 4.

presents FTIR patterns obtained for the feeds and product samplesfrom the rst hydroprocessing series.

The absorption band caused by carbonyl bond CfO suitable for

Fig. 5. Inuence of process parameters on bromine number of the hydroprocessedproducts.

Table 5Inuence of process parameters on the selected feed and hydrorened productproperties: ester content, acid number and carbon atoms content in aromatic structures.

Sample, no. Ester content,vol.%

Acid number,mg KOH/g

Acid number(IR method)

Carbon atomscontent in aromaticstructures, wt.%

Feed 1 10.0 0.48 0.46 14.69Sample1 (320, 5) 0.89 0.60 0.55 15.71Sample 3 (350, 5) 0.26 0.63 0.61 16.01Sample5 (380, 5) 0.12 0.46 0.51 16.79Sample 7 (350, 3) 0.57 0.88 0.72 15.41

Feed 2 20.0 0.49 0.48 11.66Sample2 (320, 5) 9.66 1.92 1.69 13.88Sample 4 (350, 5) 2.65 1.34 1.38 14.55Sample6 (380, 5) 0.31 1.16 1.12 16.06Sample 8 (350, 3) 4.12 2.07 2.01 14.97

690 J. Walendziewski et al. / Fuel Processing Technology 90 (2009) 6866913.6. Bromine number

Rape oil addition to diesel oil fraction almost linearly increasedbromine number of both the feeds and products as the result of themolecules presence with olen bonds in vegetable oils. Therefore,considerably higher bromine number was stated for the second seriesfeed and products (20 wt.% rape oil content, Fig. 5). Increasing of theprocess temperature and/or hydrogen pressure resulted in hydrogena-tion of double bonds and lowering bromine number of the obtainedproduct samples. It is visible that both process parameters, temperatureand hydrogen pressure, are inuencing double bonds hydrogenation.Even in the case of themost severe process conditions (380 C and 5MPahydrogen pressure) some olen compounds in hydrorened productswere determined. Due to the heightened reactivity, olens containingfuels are more susceptible to oxygenation and thus having loweredstability.

It is necessary to admit, however, that some content of olencompounds both in gasoline and diesel fuel, similarly as in the case ofbiodiesel, is admissible and, from fuel quality point of view, doesn'tpresent any tangible danger.

3.7. Ester content reduction

FTIR analysis was used to compare fatty acids and esters content inthe used feeds and the obtained hydrorening products. Fig. 6Fig. 6. FTIR spectroscopy patterns made for the I series feed and the obtainedhydroprocessed products (sulded catalyst).ester content determination is placed at the frequency 1750 cm1.Ester content in the hydrorened samples was determined on thebasis of FTIR patterns and absorption peak areas as well as calibrationcurves (ester content versus 1750 cm1 band area).

The calculation results for the rst and second series of feeds andrening products are presented in Table 5. Table 5 demonstrates veryclearly that the feed before processing contains the highest esterscontent. After that, the content was strongly reduced, the lowest valuewas found in samples 5 and 6, hydrorened at themost severe processparameters (380 C and 5MPa). One can state that at these parametersester bond content was small, almost negligible. In order to obtainrelatively high level of ester bonds hydrogenation and to lower estercontent below 0.5wt.% for the rst feed, it is necessary to apply at leastmoderate hydrorening process parameters, i.e. process temperatureat least 350 C and hydrogen pressure 5 MPa (Fig. 6).

In case of 20 wt.% vegetable oil content in the feed it is compulsoryto use higher process temperature i.e. 380 C. There is a simpledependence: the higher the vegetable oil content, the higher theprocess temperature and/or the higher hydrogen pressure should beapplied in order to obtain high level of ester bond conversion and tolower ester content below 0.5%.

It is worth noticing that hydrogenolysis of some part of ester bondsgives fatty acids that contain carboxyl group (COOH) created fromvegetable oil ester group. Therefore, acid numbers of the hydroreningproductswere higher than the feeds. It is especiallywell visible in case ofFig. 7. FTIR spectroscopy patternsmade for the II series feed and hydrorening products,the frequency range 17101750 cm1, (sulded catalyst).

products of the second experimental series,where the feedwith 20wt.%rape oil content was applied. Those observations were conrmed byFTIR studies. The band at 1710 cm1, characteristic for carbonyl bondCfO in carboxyl COOH group (Fig. 7), is suitable for the determination.Acid numbers for the products samples were calculated by thecomparison between the surface areas of those bands and calibrationcurve data. The calculation results are presented and compared to thevalues determined by the titrationmethod in the Table 5. It is visible thatboth acid content determination (acid number in mg KOH/g and acidcontent from FTIR analysis) attained similar values. It means that bothanalytic methods give similar analytical results.

It also conrms that part of ester bonds was hydrogenolized givingcarboxylic group (COOH), presumably in fatty acids. At lowervegetable oil content in the feed, 10 wt.%, there is no clear correlationbetween ester content and acid numbers. At 20% rape oil content inthe feed there is a simple dependency: the higher the rape oilconversion, the lower the ester content in hydrorening and the loweracids content (lower acid number). Process temperature stronglyinuences hydrogenolysis of ester bonds in rape oil. The highesthydrogenolysis level was determined for sample 6, hydrorened at the

Results in Fig. 8 show that application of both catalyst forms enablessimilar hydrogenolysis level of ester bonds at moderate processparameters (samples 320/3 and 320/5 for reduced form as well as320/5 and 350/5 for sulded form). Higher levels of ester bondshydrogenolysis in the presence of the both catalyst forms were attained

691J. Walendziewski et al. / Fuel Processing Technology 90 (2009) 686691highest process temperature. Similarly, as in the case of the 1st seriesproducts, one can see that acid number determinations by classic andspectroscopic give comparable results.

Absorption bands placed at wave length close to 1601 cm1 and810 cm1 are characteristic for absorption by aromatic hydrocarboncompounds. Atom percentage content in aromatic structures wascalculated on the basis of the surface area of these bands. The resultsof the calculation are also presented in Table 5. They indicate that thelowest carbon atom content was stated for both feeds while all thehydrorened samples showed distinctly higher carbon atoms contentin aromatic structures. It does not mean that in the course ofhydrorening some dehydrocyclization takes place, but that the partof parafn hydrocarbons and non aromatic fatty oils were hydro-genolysed in the course of hydrorening process. Some part of thefeed was simply removed from the hydrorening products in the formof water and light hydrocarbons, mainly propane. The most distinctlowering of carbon atoms in aromatic structures was determined forthe samples produced at the highest process temperature (380 C)and at the largest ester hydrogenolysis levels.

The obtained hydrorening results of rape oil containing feedsclearly indicate that hydrogenolysis of ester bonds gives partiallycarboxylic compounds, COOH bonds, presumably as fatty acids. Thatobservation was conrmed in quite different series of our rape oilhydrorening studies in the presence of reduced and sulded NiMoAl2O3 catalyst forms. Fig. 8 presents selected results from those studies.

Fig. 8. Comparison of the FTIR spectroscopy patterns made for the II series feed andhydrorening products over sulded and reduced catalysts, the frequency range 1710

11750 cm .in themore sever process parameters, 350/5 for the reduced and 380/5for the sulded catalyst form. Analysis of the absorption bands at1710 cm1 indicates that instead of hydrogenation to hydrocarbons, partof ester bonds in rape oil is transformed to carboxyl bonds containingacids. It is especially well visible in IR patterns obtained for the samplesfrom hydroprocessing process in the presence of the reduced catalystform (acid number from 3.84 to 7.22 mg KOH/g).

Application of the sulded catalyst resulted in considerable higherhydrogenation level of ester bonds and relatively low acid number (1.11to 1.30 mg KOH/g). It means that sulded NiMo catalyst, at similarprocess parameters as the reduced NiMo catalyst, presents higherhydrogenation activity. Mass spectroscopy analysis of the hydroproces-sing products showed that some quantity of alcohols compounds aspartial products of carboxylic acid hydrogenation is produced in thepresence of the sulded catalyst form.However, despite relatively severeprocess parameters, the hydroprocessing products contained alwayshigher quantity of fattyacids than the feed, acid number 0.49mgKOH/g.

4. Conclusions

1. Rape oil hydrorening as additive (10 or 20 vol.%) to light gas oil(diesel fuel fraction) can be realized in the temperature range 350380 C at hydrogen pressure 5MPawith good efciency. In the resultof the process one can observe over 95% yield of hydrogenolysis andhydrogenation of ester and carboxyl acid bonds as well as hydro-genation of double bonds.

2. Hydrogenation of unsaturated hydrocarbons and hydrogenolysisreactions of fatty acids results in higher melting temperaturesparafn hydrocarbons and alcohols. It leads to undesirable increasein cloud and melting points as well as CFPP determined for thehydrorened products. Some part of higher melting compoundscrystallizes in the hydrorened products.

3. Partial hydrocracking of parafn hydrocarbons causes productionof light hydrocarbons that lowers ash point of the hydrorenedsamples. If the nal process product is used as a component ofdiesel fuel, it will be necessary to remove light hydrocarbons inorder to increase its ignition temperature up to 56 C (according toPolish standards).

4. Application of hydrogenation catalysts with mild hydrocrackingand isomerization activities is necessary for the deep hydroreningprocess as amethod of the utilization of rape oil in themixturewithdiesel fraction. The catalyst application task is to support hydro-genolysis of rape oil esters bonds, hydrogenation of unsaturatedbonds and isomerization of long parafn chains. The basic goal is toobtain limited extent of hydrocracking of triglyceride molecules inthis process accompanied by possible low yield of gaseous productsand therefore low hydrogen consumption.

References

[1] G. Djega-Mariadassou, D. Brodzki, P. Nunes, J. Silva, D. Gusmao, Process for pressurehydrocracking of vegetable oils or of fatty acids derived from the said oils, FrenchPatent, FR 2607803 (1988).

[2] M. Stumborg, A. Wong, E. Hogan, Hydroprocessed vegetable oils for diesel fuelimprovements, Bioresource Technology 56 (1996) 13.

Hydroprocesssing of light gas oil rape oil mixturesIntroductionExperimentalProduct analysis

Results and discussionProduct yieldsFractional compositions and flash pointsDensityKinematics viscosityCFPP (cold filter plugging point)Bromine numberEster content reduction

ConclusionsReferences