УДК 665.644.519.863
INFLUENCE OF OZONOLYSIS ON GROUP HYDROCARBON AND ELEMENTARY
COMPOSITION OF VACUUM GAS OIL
1 12 2 2 E.A.Huseynova , L.A.Mursalova , N.N.Bagirova , F.A.Khashimov , K.Y.Adjamov ,
A.A.Dadayeva2
Scientific-research Institute "Geotechnological problems of oil, gas and chemistry " 2Azerbaijan State Oil and Industry University
Received 20.02.2017
Influence of ozonolysis on group and elementary composition of vacuum gas oil has been studied. It was determined that during ozonolysis the most change of group hydrocarbon composition has been noticed: difference in content of mono- and polycyclic aromatic hydrocarbons is increased three times (12.4 %). Also the significant growth of asphalt-resin substances: from 0.78 up to 1.42 mas. % was noticed. Subjected to adsorption purification ozonizated vacuum gas oil is characterized by significant decrease of nitrogen containing and resin-asphalten compounds: up to 0.1 and 0.51% correspondingly. It is shown that on distribution of elementary both conducting of ozonolysis and subsequent after it adsorption purification exercise influence: is accompanied by significant growth, then lay decrease of oxygen content (from 2 up to 5.1 and 3.5 mas. %) and essential decrease content of sulphure (from 1.7 up to 0.26 mas. %).
Keywords: ozonation, adsorption purification, vacuum gas oil, aromatic hydrocarbons.
Introduction
The issues, connected with preliminary preparation of vacuum gas oil as raw material for catalytic cracking are traditionally found in the centre of attention of researchers and taking into consideration the constantly increasing share of high resin and high sulphuric oils, this problem become especially actual. Numerous conducted research testify to necessity of controlling content of undesirable components in composition of catalytic cracking raw material [1-6]. So, presence of sulphuric compounds in composition of vacuum gas oil leads to intensive corrosion of used apparatus, decreases activity of catalyst and often is the base reason of disparity of received goods output to modern international standards. Influence of nitrogen compounds for a long time considered relatively inert and harmless, in essential way is tolled on decrease of yield of gas and gasoline fraction and also increase in catalyst coking degree (in 1.5-2 time). If for the last deactivation by nitrogen compound is reversible process, then about quality of cracking products to say that it is impossible: they by composition and character are approximate to products of thermal cracking: yield of hydrogen and dry gases intensively increased and yield of gasoline, which also is rich by unsaturated hydrocarbons is essentially decreased.
Also it is not to note the importance protection of catalyst from influence of metals, containing in composition of catalytic cracking raw material. This factor as the preceding, is specially strongly influence on activity and selectivity of cracking catalysts. Existence in vacuum gas oil even the very small amount of metals is accompanied by their adsorption and blocking of active centers of catalyst. Alternation of oxidation and reduction mediums and also high temperatures of usage lead to in later to caking of surface, irreversibility deactivation and mechanical destruction of catalysts.
Unlike high mentioned groups of undesirable components the increased content of sulphure in raw material of catalytic cracking exercise besides everything else exercise the negative influence on quality of additional processes of goods products improvement inevitable complicating the technological structure of oil processing plants [7-9].
In spite of that in present time it is known about 10 principal direction of preparation of catalytic cracking raw material such as thermal method, deasphaltization, sulphuric acid and adsorption purification, hydrorefining etc., but the most wide spread and studied the hydrofin-ing is stayed [9-12]. Despite the fact that some from these measures contribute to improvement
of usage and ecological indices of oil products, but often they are unprofitable from economy point of view because when all is said by processing of the such raw material the prime cost of produced product is sharply increased.
In this connection search of alternative methods improving oil distillates, among of which the oxidative technologies received a special development has become more actual [13-16].
In conducted by us works [17-20] it was noted that realization of the ozonolysis process of vacuum gas oil contributes to intensification of catalytic cracking. During research it has also been noton on existence of sediment, which in correspondence with results of IR spectrum [18] is the oxidation product of heteroatom and poly-cyclic arene compounds and also resins. Taking into consideration that the received by a number of researchers data testify to perceptivity of extractive or adsorptive separation of ozonolysis products [21, 22], within from of presented work the comparative study of change of hydrocarbon composition and sulphuric compounds of vacuum gas oil, subjected to ozonolysis with subsequent extractive and adsorptive purification have been conducted.
Experimental part
As the object of research the straight dis-tillated vacuum gas oil was choosen (Table) Q.Aliyev oil-processing plant.
Qualitative indices of vacuum gas oil
Indices Value
Density by 200C, g/sm3 0.903
Viscosity kinematic by 500C, mm2/s 25.32
Molecular mass 353
Coking, mas. % 0.16
Content of sulphure, mas. % 1.7
Content of nitrogen, mas. % 0.14
Content of resins, mas. % 1.59
Sodification temperature, 0C 24
Flash point in closed crucible, 0C 74
Fraction composition, 0C (ASTM 022887):
Start boiling 272
10% 373
30% 426
50% 456
70% 470
90% 492
Content of hydrocarbon fractions, mas. %
paraffin-naphthen 62.8
aromatic 37.2
For determination of group composition of received products the Chromatography on two adsorptive glass column (glass is pyrex) by use of silica gel by make mCM (SHSM) (for separation of paraffin-naphtene hydrocarbons from aromatic) and aluminum oxide (for separation of aromatic hydrocarbons). The total length made up 150 cm by diameter 1.5 mm, that at correlation l/d = 100 and analyzing mixture/adsorbent = 20:1 was allowing the effective separation of determined groups of components. As initial the data have been used, according to which adsorptive capacity of silica gel fflCM (SHSM) to relation oxygen-resin compounds was making 22 mg on 1g of adsorbent. Size of granules was 0.55 mm, graining 60-120 mesh.
Used combined method included 3 stages:
1. frontal method - the product is un-terruptedly flows through adsorptive column, during of which the oxygen containing and resin compounds are characterized by the most adsorption ability, displacing the hydrocarbon components take up the all volume of adsorbent;
2. washing - it is conducted by washing of hydrocarbons from column by using of isopen-tane or petroleum ester;
3. displacement - if it was demanded to displace the all sum of oxygen containing and resin compounds, then as extractant the alcohol benzene mixture was used; if it was necessary to separate the oxygen containing and resin compounds, then at first the benzene was passing and then alcohol because benzene desorb the neutral oxygen containing compounds and alcohol - acid and resin.
Washing was finished when from column a colorless filtrate began to come.
For separation of paraffin-naphten, mono- and becyclic aromatic hydrocarbons the petroley ester, polycylic - benzene and for oxygen containing and resins consecutively - acetone and alcohol-benzene mixture are used.
The adsorption purification has been conducted by use of bentonite clay, which is characterized by the following indices: specific surface - 150-200 m /g;
"3
density - 1.45 g/cm ;
"3
adsorptive capacity by benzene - 0.12-0.13 g/cm .
Correlation of vacuum gas oil amount to
adsorbent made up 6:1, rate of raw material feed - 0.45 cm3/min. Before beginning of experiment, adsorbent was calcinated during 5 h in muffle cabinet at 2500C. Rate passage of solution made up 0.3 ml/min, the process was conducting by temperature 500C. During preliminary experiments it have been determined that given temperature is optimum by which decrease of viscosity become enough for penetration of components in pores of adsorbents.
The element analysis of initial, ozonated and subjected to adsorption purification vacuum gas oil was made on CHNS-analizator vario EL Cube.
This work was supported by the Science Development Foundation under the President of the Republic of Azerbaijan - Grant №EIF -KETPL -2 - 2015 - 1(25) - 56/24/4.
Discussion of results
From Figure 1 data it is evident that a base group composition of initial and ozonated gas oil stayed invariable, but at the same time correlation of component changed: the base hydrocarbons are paraffin-naphten (from 59.7 up to 62.
aromatic hydrocarbons make up 37.2-38.8% among which the hydrocarbons containing two and more aromatic ring predominate. It testifies to that during ozonation composition of aromatic hydrocarbons sharply is complicated: if the initial vacuum gas oil has difference in content of mono and poly cyclic aromatic hydrocarbons make up 4.6%, then in composition of ozonated fraction this difference is increased nearly three times (12.
Group hydrocarbon composition
di- and poly-aromatic
mono aromatic
1.5
1.2
0.9
0.6
0.3
olefine
paraffine-naphtene
Heteroatom compounds
nitrogen containing
sulphur-containing
asphalto-resin
0
20
40
60
80 100 Content, % mas
Fig. 1. Characteristics of group composition of initial and ozonated vacuum gas oil.
0
Probably, it is connected with growth of reaction ability of aromatic compounds in reactions of electrophilic addition by transition from mono- to bi and nigh cyclic structures.
According to literary data [23-27] all types of saturated hydrocarbons (alkanes, naphtens, al-kyl-aromatic) which have been identified during this research in raw material of catalytic cracking in presence of nitrogen enter with him both in reaction of electrophilic addition and oxidation, proceeding by radical-chain mechanism.
The high content of compounds with two or more aromatic rings and alkyl substituent's in molecule, characterized by high constant rate of oxidation lead to increase of reaction condensation contribution and accumulation of resin-asphalte compounds. The last is undesirable owing to increase of coking on catalyst surface and essential deterioration of technological-economic indices of the process catalytic cracking. The received results indicate on necessity conduction of the process purification of ozonated vacuum
gas oil from undesirable components (polyaro-matic and asphalt-resin compounds). By this aim the adsorption purification have been choosen.
By selection of adsorbent for determination of optimal conditions removal of polar products from composition of ozonated vacuum gas oil, it was one can to take into consideration role of three factors: influence of structure, nature of solid surface and nature of solvent. As a result the hydrophilic adsorbent - natural bentonite clay was choosen on base of mount morillonite (Azerbaijan Republic, Nakhichevan, Djanabab deposit) which according to rule of A.P.Rebinder. Characterized by bad wetting inpolar hydrocarbon phase surface that creates the optimal conditions for adsorption of dissolved in it polar compounds. Absence of asphaltens also is favourable factor because the last, possessing by considerably more than resin sizes, are inclined to cut off pores and to prevent adsorption of the last.
The group hydrocarbon composition of ozonated gas oil, subjected to adsorption purification of ozonated vacuum gas oil include in itself: paraffine-naphtene - 60.6%; olefine - 4.10; aromatic - 35.84 (from them - mono- 12.8; bi-17.5; tri- and poly- 5.54). Comparison of group hydrocarbon composition of ozonated vacuum gas oil and further subjected to adsorbtion purify-
cation show that in the process of adsorption purification in the most degree a tri- and polycyclic aromatic compounds and also unsaturated are removed. Decrease of sum amount of aromatic hydrocarbons lead to increasing of share of saturated components (content of paraffine-naphtene hydrocarbons increase by 5.6%). On the following stage the investigations by influence of ozo-nation and subsequent adsorption purification of ozonated gas oil on it element composition have been conducted (Figure 2).
Conducting ozonolysis and subsequent for it adsorption purification lead to redistribution of elements in composition of vacuum gas oil: ozonolysis is accompanied by significant growth of oxygen content on account of heteroatom oxygen containing compounds (derivatives of sulpho acids, sulphones sulpho oxide, pyridine compounds, wide series of carbonyl acids, phenols, alcohols compounds of peroxides type and etc.) whereas later after adsorption purification share of oxygen is decreased.
In composition of ozonated vacuum gas oil, subjected to adsorption purification content of sulphur also is decreased (from 1.7 up to 0.26%) on account of adsorption of polar sulphur containing components (sulphones and sulpho oxides).
ox
S
0
1 o
s
<d
m
o O
ox
o x
s
<d
o O
Initial vacuum Ozonated vacuum Ozonated after gas oil gas oil adsorption puri-
fication
Fig. 2. Influence of ozonolysis and subsequent adsorption purification on element
composition of vacuum gas oil
- oxygen; -•- - sulfur;----nitrogen; ED - carbon
content; ^ - content of heteroatom compounds.
Although decrease of nitrogen content was not expected, taking into consideration that ozon practically does not attack nitrogen containing compounds of oil, but by that growth of nitrogen content in ozonated sample of vacuum gas oil was showen slightly groundless. It is probably contribution of forming in atmosphere ozone in another strong oxidant - nitrogen oxide and it interaction both with hydrocarbons and with heteroatom components of vacuum gas oil.
Thus, the received results testify to efficiency use of uncatalytic method for desul-phurization of catalytic cracking raw material by ozonolysis as alternative to traditional hy-drofining. Unlike from the last, ozonation of oil fraction is conducted by atmospheric pressure and room temperature, does not demand existence of catalysts and hydrogen and separation of undesirable component is conducted by adsorption purification by moderate temperatures.
Conducting of adsorption purification by condition of subsequent separation of polar oxygen containing resin and high molecular aromatic compounds will allow, basing on it surface-active properties to use them in future in oil-chemical industry.
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VAKUUM QAZOYLUNUN KARBOHiDROGEN QRUP VO ELEMENT TORKiBiNO OZONOLiZiN TOSiRi
E.O.Hüseynova, L.A.Mürsalova, N.N.Bagirova, F.A.Ha$imov, K.Y.Ocamov, O.O.Dadayeva
Vakuum qazoylunun karbohidrogen qrup уэ element tarkibina ozonolizin tasiri öyranilmiijdir. Ozonla§ma zamani aromatik karbohidrogenlarin qrup karbohidrogen tarkibinda kigik dayi§iklik ba§ verir: mono- уэ politsiklik aromatik karbohidrogenlarin miqdari arasindaki farq üg dafa artir (12.4%). Eyni zamanda asfalt-qatran birb§mabrinin ahamiyyatli artimi mü§ahida olunur: 0.78 kütla %-dan 14.2 kütla %-э. Adsorbsiyali tamizlama zamani azottarkibli уэ birb§mabrin miqdarinin uygun olaraq 0.1% уэ 0.51%-э qadar azalmasi qeyd olunmu§dur. Göstarilmi§dir ki, adsorbsion tamizlanma elementlarin paylanmasina tasir edir: oksigenin miqdari эууэ1 artir, conra azalir (2 kütla %-dan 5.1 уэ 3.5 kütla %-dak), azotun miqdari artir (0.7 kütla %-dan 0.85 kütla %-dak) kükürdün miqdari azalir.
Agar sözlar: ozonla§ma, adsorbsion t3mizhnm3, vakuum qazoylu, aromatik karbohidrogenlar.
ВЛИЯНИЕ ОЗОНОЛИЗА НА ГРУППОВОЙ УГЛЕВОДОРОДНЫЙ И ЭЛЕМЕНТНЫЙ
СОСТАВ ВАКУУМНОГО ГАЗОЙЛЯ
Э.А.Гусейнова, Л.А.Мурсалова, Н.Н.Багирова, Ф.А.Хашимов, К.Ю.Аджамов, А.А.Дадаева
Изучено влияние озонолиза на групповой и элементный составы вакуумного газойля. В ходе озонирования наибольшие изменения группового углеводородного состава отмечены для ароматических углеводородов: разница в содержании моно- и полициклических ароматических углеводородов увеличивается втрое (12.4%). Также отмечен значительный рост количества асфальто-смолистых веществ: с 0.78 до 1.42 мас.%. Подвергнутый адсорбционной очистке озонированный вакуумный газойль характеризуется значительным уменьшением содержания азотсодержащих и смолисто-асфальтеновых соединений: до 0.1% и 0.51% соответственно. Показано, что на распределение элементов оказывает влияние как проведение озонолиза, так и последующая за ним адсорбционная очистка: сопровождается значительным ростом, затем снижением содержания кислорода (с 2 до 5.1 и 3.5 мас.%), повышению содержания азота (с 0.7 до 0.85 мас.%) и существенному снижению содержания серы (с 1.7 до 0. 26 мас.%).
Ключевые слова: озонирование, очистка адсорбции, вакуумный газойль, ароматические углеводороды.