Synthesis and application of a spirocompound as clean viscosity-reducer for crude oil

Article abstract of DOI:10.1155/2016/3827403

Heavy oil transportation has become a highly technical operation facing complex difficulties. One of the major difficulties in the pipeline transportation is the high viscosity that requires efficient and economical ways to deal with. The typical polymer viscosity reducers are a negative problem during oil refinement process for their chemical properties. The objective of this study is to seek small molecular compound, different from the traditional polymers, to reduce the viscosity of the crude oil. In this work, a spirocompound, 3,9-diphenyl-2,4,8,10-tetraoxa-spiro[ 5.5 ]undecane, was synthesized catalyzed by zeolite and modified zeolite, and the product was fully characterized by NMR, MS, and TG. Then, it was used as viscosity reducer for crude oil. The factors such as dosage and temperature on the viscosity behavior have been studied. The results showed a significant viscosity reduction at different temperature, and the most economical dosage is 500 ppm. The multiphenyl groups can interact with asphaltene by π - π stacking, and the spirostructure can fix the stacking in different direction, which can prevent the agglomeration of wax crystals.

Full text of DOI:10.1155/2016/3827403

Hindawi Publishing Corporation
Journal of Chemistry
Volume 2016, Article ID 3827403, 5 pages
http://dx.doi.org/10.1155/2016/3827403
Research Article
Synthesis and Application of a Spirocompound as
Clean Viscosity-Reducer for Crude Oil
Shijun Chen,1,2 Kang Zhao,1 Gang Chen,2 Li Bai,1 and Lajun Feng1
1School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048, China
2College of Chemistry and Chemical Engineering, Xi’an Shiyou University, Xi’an, Shaanxi 710065, China
Correspondence should be addressed to Shijun Chen; csjun@xsyu.edu.cn and Gang Chen; gangchen@xsyu.edu.cn
Received 16 November 2015; Revised 13 January 2016; Accepted 20 January 2016
Academic Editor: Barbara Gawdzik
Copyright © 2016 Shijun Chen et al. is is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Heavy oil transportation has become a highly technical operation facing complex difficulties. One of the major difficulties in the
pipeline transportation is the high viscosity that requires efficient and economical ways to deal with. e typical polymer viscosity
reducers are a negative problem during oil refinement process for their chemical properties. e objective of this study is to
seek small molecular compound, different from the traditional polymers, to reduce the viscosity of the crude oil. In this work,
a spirocompound, 3,9-diphenyl-2,4,8,10-tetraoxa-spiro[5.5]undecane, was synthesized catalyzed by zeolite and modified zeolite,
and the product was fully characterized by NMR, MS, and TG. en, it was used as viscosity reducer for crude oil. e factors
such as dosage and temperature on the viscosity behavior have been studied. e results showed a significant viscosity reduction
at different temperature, and the most economical dosage is 500 ppm. e multiphenyl groups can interact with asphaltene by ꢀ-ꢀ
stacking, and the spirostructure can fix the stacking in different direction, which can prevent the agglomeration of wax crystals.
1. Introduction
2. Experimental
Oil transportation has become a complex and highly tech-
nical operation. One of the major difficulties in the pipeline
transportation is the high viscosity that requires efficient
and economical ways to deal with [1–3]. erefore, different
methods are used in order to reduce the viscosity of the
heavy crude for the pipeline transportation [4, 5], such as
dilution with lighter crudes or alcohols, heating, and the
use of chemical additives. e typically chemical additives
are polymers having a wax-like paraffinic part and a polar
component, such as homo- and copolymers of alpha olefins
[6], polyalkyl acrylates and methacrylates [7–9], alkyl esters
of styrene-maleic anhydride copolymers [10–12], ethylene-
vinyl acetate copolymers [13], and alkyl fumarate-vinyl
acetate copolymers [14]. But the long molecular chain, large
molecular weight, and high thermostability of these polymers
are a negative problem during oil refinement process [15]. So
it is necessary to seek small molecular crude oil additives. In
this paper, a spirocompound, 3,9-diphenyl-2,4,8,10-tetraoxa-
spiro[5.5]undecane, was managed to be synthesized and
evaluated as a viscosity reducer for crude oil.
2.1. Materials. Chemicals were either prepared in our labora-
tories or purchased from Merck, Fluka, and Aldrich Chemical
Companies. All yields refer to isolated products. e products
were characterized by comparison of their physical data with
those of known samples or by their spectral data. NMR
spectrum was recorded in the stated solutions, on a Bruker
Drx-500 spectrometer, operating at 500 MHz for 1H; ꢁ values
are reported in ppm and ꢂ values in hertz. Mass spectrum
was recorded on a Micromass Platform II spectrometer,
using the direct-inlet system operating in the electron impact
(EI) mode at 75 eV. ermal analysis was performed on a
TGA/SDTA851e ermal Analyzer, where the heating rate
was 10 K min−1 in the range of 298–880 K.
2.2. Method. Initially, the crude oil was homogenized by
shaking it for an hour to ensure that the physical properties of
the heavy crude oil are the same. Afer homogenization, the
crude oil was used for measurements. e crude oil samples
used in this study were obtained from Jinghe Oilfield, China.

2
Journal of Chemistry
HO
HO
OH
OH
O
O
O
O
O
Catal.
+
Scheme 1: Synthesis of 3,9-diphenyl-2,4,8,10-tetraoxa-spiro[5.5]undecane.
100
90
80
70
60
50
40
30
20
10
0
Table 1: e group compositions of the crude oil.
Saturated HC (%) Aromatic HC (%) Resin (%) Asphaltene (%)
54.04 25.88 19.24 0.84
e density of the used heavy crude oil is 905 kg/m3 at 15∘C,
and the pour point is 34.8∘C. e group compositions of the
crude oil are shown in Table 1.
NaY
ZSM-5
4A
2.3. Synthesis of 3,9-Diphenyl-2,4,8,10-tetraoxa-spiro[5.5]un-
decane. Benzaldehyde and pentaerythritol were added in a
flask with the molar ratio of 2 : 1, and the toluene was added
as the water carrier and the solvent. 5% (wt) solid acid, zeolite,
was added as catalyst. e mixture was refluxed until no
water can be carried out and was cooled to room temperature.
e zeolite was filtrated, and the solvent was evaporated to
produce the crude product. Recrystallized in methanol, the
Zeolite
Sulfonated zeolite
Figure 1: e yield of 3,9-diphenyl-2,4,8,10-tetraoxa-spiro[5.5]un-
decane catalyzed by zeolite.
120
100
80
60
40
20
0
pure product was obtained as colorless block. e reaction
1
is described in Scheme 1. H NMR (500 MHz, CDCl ) ꢁ:
3
7. 22∼7.52 (m, 10H), 5.41 (s, 2H), 4.72 (d, ꢂ = 7.5 Hz, 2H),
3.88 (d, ꢂ = 7.5 Hz, 2H), 3.72 (d, ꢂ = 7.0 Hz, 2H), 3.63 (d,
ꢂ = 7.0 Hz, 2H); IR (KBr) ]: 3010, 2985, 2885, 1566, 1529, 1480,
1378, 1116 cm−1.
2.4. Viscosity of the Treated Crude Oil. Crude oil sample
was doped with cyclohexanone pentaerythritol ketal butanol
solution with concentrations of 100, 300, 500, 800, or
1000 ppm. e viscosity measurements were carried out at
test temperatures of 30–50∘C, representative of temperatures
greater than, equal to, and lower than the pour point of the
crude oil, respectively.
0
5
10
15
20
25
Dosage (%)
Figure 2: e effect of the dosage of ZSM-5 on the yield of 3,9-
diphenyl-2,4,8,10-tetraoxa-spiro[5.5]undecane.
3. Results and Discussion
from 1% to 20%, and the results are shown in Figure 2. From
the results, it can be seen that the low amount of catalyst is
not efficient to cause the reaction to happen. With increasing
the amount to 15%, yield of 3,9-diphenyl-2,4,8,10-tetraoxa-
spiro[5.5]undecane increases up to 97.2%. e reason for
the increased conversion with an increase in the catalyst
weight should be attributed to the increase in number of
catalytically active sites provided by large amount of ZSM-5.
Further increasing the amount of catalyst to 20%, the yield
does not increase further.
3.1. Synthesis. 3,9-Diphenyl-2,4,8,10-tetraoxa-spiro[5.5]un-
decane has been synthesized using I as catalyst with high
2
yield, but it is complex to remove the catalyst afer the
reaction [16]. In this synthesis, three kinds of zeolite and
corresponding sulfonated species were screened, and the
results were shown in Figure 1. From the results, it can be
found that the catalytic activity is quite different. For the
zeolite, NaY and ZSM-5 are active for this reaction, and
ZSM-5 is the most effective one with the yield of 97.2%,
compared with 3.9% for 4A. Afer the sulfonation, all the
yields are increased. e yield of 3,9-diphenyl-2,4,8,10-
tetraoxa-spiro[5.5]undecane increases to 95.0%, 98.2%, and
25.0%, respectively, which may be due to the increased
acidity by sulfonation.
3.2. Isomers. For the fixed spirostructure, the 3,9-diphenyl-
2,4,8,10-tetraoxa-spiro[5.5]undecane has four kinds of iso-
mers, shown in Figures 3(a)–3(d). In molecular (a) and
(d), the two phenyl groups are trans-conformation, and,
in molecular (b) and (c), the two phenyl groups are cis-
conformation. It should be noticed that molecular (a) can
transfer to molecular (d) by rotating with 180∘, and molecular
In the following work, the effect of the dosage of
ZSM-5 on the yield of 3,9-diphenyl-2,4,8,10-tetraoxa-
spiro[5.5]undecane was investigated by varying the dosage

Journal of Chemistry
3
O
O
O
O
O
O
O
O
O
O
O
O
O
O
(a)
(c)
(b)
(d)
O
O
Figure 3: e isomers of 3,9-diphenyl-2,4,8,10-tetraoxa-spiro[5.5]undecane.
H
H
H
H
H
H
O
O
O
O
O
O
O
O
H
H
(a)
(b)
Figure 4: e H-H correlations of isomer (a) and (b).
1600
1200
800
400
0
120
100
80
60
40
20
0
25
75
125
175
225
275
325
375
425
0
200
400
600
Dosage (ppm)
800
1000
1200
Temperature (∘C)
Figure 5: e TGA curves of 3,9-diphenyl-2,4,8,10-tetraoxa-
spiro[5.5]undecane.
30∘C
35∘C
45∘C
40∘C
50∘C
Figure 6: e relation of dosage and viscosity.
(b) can transfer to molecular (c) by the same way as well. So
there are two kinds of isomers in fact.
e NMR spectrum of 3,9-diphenyl-2,4,8,10-tetraoxa-
spiro[5.5]undecane shows that multiple peaks at ꢁ 7. 22∼7. 52
(m, 10H) are due to the H of phenyl groups. e single peak
at 5.41 (s, 2H) is due to the ꢃ-H of the phenyl group, which
is inducted by two O atoms resulting in the relatively high
the temperature increases above 205∘C, the crystal starts
to lose weight sharply. e first stage of weight loss is
only about 1.2% between 25 and 205∘C, which may corre-
spond to the loss of absorbed solvent. e second stage of
weight loss is about 96% between 205 and 319∘C, which
corresponds to the decomposition of 3,9-diphenyl-2,4,8,10-
tetraoxa-spiro[5.5]undecane. Above 319∘C, the remaining
weight ratio is only <2.7%, which corresponds to the residues
of carbon deposit. e thermal performance indicates 3,9-
diphenyl-2,4,8,10-tetraoxa-spiro[5.5]undecane easy decom-
position under relative lower temperature than that of poly-
mer, which means it may be a cleaner crude oil additive than
polymers additives.
chemical shif. For the four CH groups, it seems that the
2
four groups are under the same chemical condition and will
have the same chemical shif but show four different chemical
shifs. Analyzing the stereogenic configuration of isomers (a)
and (b) (as shown in Figure 4), it can be found, with the
fixed spirostructure, that H atoms of the phenyl groups can
correlate with certain stereogenic CH group, which can lead
2
to two kinds of CH group in each isomer. So as a result, there
2
are four kinds of CH groups corresponding to four chemical
2
shifs.
3.4. Viscosity-Reducing Performance. 3,9-Diphenyl-2,4,8,10-
tetraoxa-spiro[5.5]undecane was evaluated as a viscosity
reducer for a crude oil, and the results were shown in Figures
6 and 7. Figure 6 shows the crude oil viscosity as a function
3.3. ermal Gravimetric Analysis. e TGA analysis of 3,9-
diphenyl-2,4,8,10-tetraoxa-spiro[5.5]undecane was shown in
Figure 5. It indicates that it is stable below 200∘C, but as

4
Journal of Chemistry
1600
1200
800
400
0
30
35
40
45
50
55
Temperature (∘C)
Blank
300ppm
800ppm
100ppm
500ppm
1000 ppm
Figure 7: e relation of temperature and viscosity.
Isomer (a)
Isomer (b)
Figure 8: e steady conformations of isomers (a) and (b).
of the dosage under different temperature, respectively. It
reduces the crude oil viscosity depending on dosage. At
each temperature, the higher the concentrations were, the
better the reduction was observed obviously with the dosage
below 500 ppm. While the dosage rises up to over 500 ppm
(800 ppm and 1000 ppm), the viscosity does not reduce
effectively. So the economical use of this kind of viscosity
reducer is 500 ppm. Under this condition, the viscosity was
reduced from 1460 mPa⋅s to 882 mPa⋅s at the relative low
temperature of 30∘C. If the 1000 ppm was used, the viscosity
can be reduced to 186 mPa⋅s at the 50∘C, which can be
a usable additive in the present China pipeline transports
crude oil. Also, Figure 7 shows the crude oil viscosity is a
function of the temperature in the presence of 100, 300, 500,
800, and 1000 ppm, respectively. e behavior of reducing
the viscosity afer addition of 3,9-diphenyl-2,4,8,10-tetraoxa-
spiro[5.5]undecane can thus be attributed to the chemical
structure.
e slight polarity of the benzene ring and the presence
of high polarity of oxygen play a role [17, 18]. e steady
conformations of isomers (a) and (b) were expressed in
Figure 8, which were simulated by a minimized energy of
MM2 in Chem 3D. In both conformations, the two phenyl
groups display a dihedral angle of about 90∘. e multiphenyl
groups can interact with asphaltene by ꢀ-ꢀ stacking [19], and
the spirostructure can fix the stacking in different direction,
which can prevent the agglomeration of wax crystals in crude
oil.
4. Conclusion
e objective of this study is to investigate the small molec-
ular compounds, different from the traditional polymers,
to reduce the viscosity of the crude oil. In this work,
3,9-diphenyl-2,4,8,10-tetraoxa-spiro[5.5]undecane was syn-
thesized under optimized conditions. en, it was evaluated

Journal of Chemistry
5
as viscosity reducer for crude oil. A wide range of temperature
was covered in this study to examine the effect of temperature
on the flow behavior of the crude oil. e results showed
that the viscosity was reduced from 1460 mPa⋅s to 882 mPa⋅s
at the relative low temperature of 30∘C with the dosage of
500 ppm; the viscosity can be reduced to 186 mPa⋅s at the 50∘C
and with the dosage of 1000 ppm. is work found that the
small spirocompound rather than the polymers can be used
as viscosity reducer for crude oil.
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Conflict of Interests
[14] Y. Song, T. Ren, X. Fu, and X. Xu, “Study on the relationship
between the structure and activities of alkyl methacrylate–
maleic anhydride polymers as cold flow improvers in diesel
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2005.
e authors declare that there is no conflict of interests
regarding the publication of this paper.
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Acknowledgment
London, UK, 2000.
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National Natural Science Foundation of China (21376189).
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