Reduced hydrogen sulfide from crude oil using metal nanoparticles produced by electrochemical deposition

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Research Article

Reduced hydrogen sulfide from crude oil using metal nanoparticles

produced by electrochemical deposition

Sahar Safarkhania,b*, Ali Akbar MiranBeigia, Amir Vahia and Abolghasem Mirhoseinib

a

Oil Refining Research Division,

Research Institute of Petroleum Industry,Tehran,Iran b

Department of Environmental pollution, Yazd Branch, Islamic Azad University, Yazd, Iran

Email: s.safarkhani.66@gmail.com *

ABSTRACT

Hydrogen sulfide is one of the most dangerous contaminants in crude oil and natural gas that must be removed before transport and refining. It has multiple effects on the environment and the industry is bad that these effects include acid rain, cancer, corrosion of pipelines, poison catalytic converters in car exhaust. In this study, to eliminate H2S crude oil Nano emulsion used ionic liquid. Ionic liquids also with metal nanoparticles (MNPs) have been modified. Improve and reform the electrochemical deposition of metal salts is done. Ionic liquid 1 - Hydro One Atyl2- methyl imidazolium de cyanimide [HEMIM] [DCA] is inherently hydrophilic as Scavenger H2S was added to the crude oil. Two types of metal salts of Fe (acac) 3 and Cu (SO4) electrochemical deposition method for producing metal nanoparticles in the ionic liquid [HEMIM] [DCA] was used. Suitable concentrations of ionic liquids for the complete removal of hydrogen sulfide from crude oil were determined by two methods: static and dynamic methods. Dynamic method to determine the required dose used to remove H2S. Static method using response surface and through statistical experimental design for modeling and assessment CCD H2S was removed parameters. Three factors, namely Scavengerdose, contact time and the reaction temperature were studied. The interaction between these factors on the concentration of H2S in the crude oil was studied. 3 important statistical models for ionic liquids and ionic liquid containing two types of metal nanoparticles were developed. This model has an index of non- compliance was not important. The ionic liquid modified with nanoparticles , activity and H2S removal capacity is significantly increased , to the extent that the effect of one or two major factors were considered too small or unimportant . Copper metal nanoparticles showed better performance for the removal of H2S to iron

Keywords: hydrogen sulfide, ionic liquid, nanoparticles, electrochemical synthesis, petroleum, Design of Experiments

INTRODUCTION

Liquid oil is mainly made up of hydrogen and carbon and organic elements with smaller amounts of other elements such as sulfur, Nitrogen, oxygen and naturally underground and is sometimes found on the ground. The root words of the word Avesta naphtha oil is taken indeed separate oil refining and enhancing the purity of the components of crude oil and reduce its pollutant elements (sulfur, nitrogen, vanadium, etc.).

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elements are, through their identification as the source of the contaminated oil discovered For example, this method of oil pollution studies in the wetland after the Gulf War was used to determine the share of pollution of the Gulf War.

Sulfur is the third most abundant element in crude oil. The amount of sulfur in the crude oil of about 0.05 - 5 [Czogalla, 1983] wt. %. In recognition of several hypotheses about the origin of organic sulfur compounds and sulfur interactions have been discussed with the carbon cycle in the geosphere.sir and Pyzant [cry, 1986] the source of sulphides two rings, four rings and considered Hvpan in oil biosynthesis. But none of the organic sulfur compounds or functional groups in their reports have not been reported in plants and animals. Although the elemental sulfur is everywhere , including some amino acids found in living organisms , such as the source of all levels of sulfur in the crude oil cannot be linked to sulfur in plants and animals Because of the high concentration of sulfur in living organisms there . Sulfur organic compounds which are as follows, usually in crude oil distillation cuts are [Payzant, Montgomery, 1983]

• Thioether or sulfides (RSR) • Disulfides (R-S-S-R)

• Thiol or mercaptan of (R-SH) • Theophany and its derivatives • Sulfoxide

• Sulphonates

Cut with a boiling point higher, relatively more sulfur compounds, have a higher molecular weight. Cuts mainly organic sulfur compounds with low boiling point are aliphatic.

Research Methodology:

International standards known as ASTM, UOP, API, IP, DIN and ISO standard methods for the detection and measurement of sulfur and its compounds in the oil and oil products have provided.

For the measurement of crude oil and condensate in the project, one of the strictest and most widely used method UOP 163 standard methods, is used. The method for measuring hydrogen sulfide and mercaptan

sulfur by potentiometric titration method is based on liquid hydrocarbons. The following figure shows the measurement device UOP 163 Hydrogen sulfide standard. The concentration of hydrogen sulfide and mercaptan is calculated in units of mass ppm. In this way, a certain amount of samples containing a small amount of ammonia dissolved in isopropyl alcohol and then by potentiometric titration with silver nitrate is. The titration according to the following reaction takes place.

1 reaction

2 reaction

3 reaction

The amount of silver nitrate consumed is proportional to the concentration of hydrogen sulfide.

H2S in crude oil, according to the study, about ppm 186 UOP163 that according to regulations enacted by Vopak Terminals in Europe, Iranian crude oils in terms of the amount of hydrogen sulfide should be less than 15 ppm is used for the purpose of ionic liquids. External sources and codified a standard method to evaluate performance and assess Scavengers there is usually based on scoring and ranking them in terms of features that should have a Scavenger, Done. However, in this project from both dynamic and static experimental method is used. By working in a dynamic way based on the gradual increase in measured ionic liquids and crude oil potential changes in time steps is fixed.

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changes over time or the dose was Scavenger curve shown in Figure 1. It also required volume of ionic liquid to deliver hydrogen sulfide concentrations to less than 15 ppm also specifies. When the electrode potential is less than -750m V moved, the concentration of hydrogen sulfide is less than 15 ppm. Ionic liquid [HEMIM] [DCA] The change does not show a lot of potential but very steep and sudden decline in the -10minute time creates potential, And after potential remains relatively steep slope decreases, in the end also brought about -730 mV, which represents a decrease of H2S is less than 10 ppm, In this method, the amount of hydrogen sulfide in crude oil gr5 using UOP163 measured, then the dose of ionic liquid is added to the crude oil in question. According to the results of the dynamics as well as operating conditions at oil terminals, the required dose of ionic liquids, Mixing time and temperature required for removing hydrogen sulfide from crude oil to be determined. Following the crude oil export terminals present requests and claims Scavenger companies like Nalco, Baker in terms of crude

oil temperature, Scavenger dose and duration of crude oil through the tubes became clear The ionic liquid hydrogen sulfide should be required to remove the mole ratio of 2 to 10 times the concentration of H2S Reaction time from 15 to 45 minutes and mixing temperatures of 25 to 50 degrees Celsius considered. After identifying these factors and by using Design Expert for ionic liquid [HEMIM] [DCA] and the design of experiments to investigate the effect and interaction of these factors and the optimum conditions H¬2S removal was done by CCD. Using dynamic parameters or factors in the concentration of hydrogen sulfide was detected and the experimental design was done by software Design Expert And how to analyze them using RSM (responses urface) has been done for the ionic liquid [HEMIM] [DCA] is the Run 18 or experiment And various conditions such as dose Scavenger to H2S, temperature and reaction time tests are conducted on the basis of and the results are entered in the column for the answer.(Table 1)

Table 1. Shows the design of the experiment and its results for the ionic liquid [HEMIM] [DCA]

std run [IL] / [ H2S] TEMP TIME Response [HEMIM][DCA]

5 1 2 25 45 1024

13 2 6 37/5 15 1085

3 3 2 50 15 993

11 4 6 25 30 1051

4 5 10 50 15 1039

1 6 2 25 15 1085

6 7 10 25 45 916

16 8 6 37/5 30 1066

12 9 6 50 30 966

17 10 6 37/5 30 1018

18 11 6 37/5 30 1025

2 12 10 25 15 1081

10 13 10 37/5 30 959

14 14 6 37/5 45 1037

15 15 6 37/5 30 982

7 16 2 50 45 824

8 17 10 50 45 787

9 18 2 37/5 30 1050

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interactions to prevent Meanwhile, the lack of fit (LOF) is a good model should also unimportant and ineffective. Non important each feature or element with its F value and measure it with the F value in the statistical tables compare the desired confidence level. Sometimes, instead of ensuring that the level of use in terms of contemporary conceptual confidence level. The F value is greater than the F table , it is more important features , For the model that features a lower LOF , which model is better and less error can change in response to statements equation ( model ) and factors related to the confidence level .After selecting the appropriate model based analysis of variance. According to the method is determined whether the temperature factor or interaction was significant and important effect on the response or not and if it also has value as a comparison to help determine the F-test . As Table 2 derived from the non- linear model of LOF is important as the adaptability of the model with experimental data was.(Table2)

Table 2 - Comparison LOF for a variety of models [HEMIM] [DCA]

Models Sum of

squares df Mean square F value

p-value probe>F

Linear 35830.75 11 3257.340909 2.74591436 0.2198 Suggested

2FI 24876.375 8 3109.546875 2.621325079 0.2308

Quadratic 8677.720238 5 1735.544048 1.46305083 0.4007

Cubic 1365.720238 1 1365.720238 1.151292087 0.3619 Aliased

Pure Error 3558.75 3 1186/25

According to Table 3, F model is not high and the confidence that the linear model to explain the behavior of the system, And the main factors as time, temperature and doses are most effective And the effects of two factors, AC, BC and AB are less effect and can be reached between the factors B2, A2 and C2 are in effect. After moving the adaptability of experimental results and effective unimportant effects were eliminated.(Table3)

Table 3. Analysis of variance (ANOVA) of the linear model derived from experimental data [HEMIM] [DCA]

Model 83926.625 4 20981.65625 7.26214244 0.0027 significant

A-[S]/[H2S] 3763.6 1 3763.6 1.30265213 0.2743 significant

B-TEMP 30030.4 1 30030.4 10.3940814 0.0067 significant

C-TIME 48302.5 1 48302.5 16.7183959 0.0013 significant

AB 1830.125 1 1830.125 0.70797561 0.4180 not significant

AC 4371.125 1 4371.125 1.69095001 0.2201 not significant

BC 4753.125 1 4753.125 1.83872499 0.2023 not significant

A^2 4568.203149 1 4568.203149 2.98661497 0.1222 not significant

B^2 3721.493472 1 3721.493472 2.43305032 0.1574 not significant

C^2 646.0096006 1 646.0096006 0.42235029 0.5340 not significant

Residual 28435.125 11 2585.011364

Lack of Fit 24876.375 8 3109.546875 2.62132508 0.2308 not significant

Pure Error 3558.75 3 1186.25

Cor Total 121486 17

Table 4. Analysis of variance of the linear model derived from experimental data after the adaptability of this [HEMIM] [DCA]

Models Sum of squares df Mean square F value p-value probe>F

Model 82096.5 3 27365.5 9.72637378 0.0010 Significant

A-[S]/[H2S] 3763.6 1 3763.6 1.337676284 0.2668 not significant

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Pure Error 3558.75 3 1186.25

Cor Total 121486 17

As shown in Table 4 was found after the adaptability of the experimental data is the most effective and influential after the temperature has.

Equation (1) the actual amounts of invoices for [HEMIM] [DCA]

R1 = +1183.52083 -4.50625 * [S]/[H2S] -2.29900 * TEMP +2.57917 * TIME +0.30250 * [S]/[H2S] * TEMP -0.38958 * [S]/[H2S] * TIME -0.13000 * TEMP * TIME

A linear diagram in( Figure 1) , there is little slope , and the dose is not effective in reducing H2S is very little effect on the response .In Chart B tilt more and more influence in the process of reducing the potential is much higher temperature .Figure C is similar to B charts and more H2S is reduced with increasing time

A

B

C

Figure 1 shows the effect of three varying doses of ( A) , temperature ( B ) and time ( c) [HEMIM] [DCA] After the ionic liquid synthesis of metal

nanoparticles in ionic liquids has been studied

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reported. The most common among them the deposition, thermal decomposition method,

Solvothermal and Hydrothermal, synthetic micro- emulsion, reverse micelle, sol-gel and electrochemical deposition cited. In this research, nanoparticles in ionic liquids using electrochemical deposition has been done, there are a large number of metal ions of which were selected by the technique of copper and iron. Because of the availability of the corresponding metal salts, appropriate processing techniques, cost, and potential oil well is in harmony with the tissue reacts with sulfur compounds, particularly hydrogen sulfide from the show Attended. Electrochemical deposition method for the synthesis of metal nanoparticles in ionic liquids needs to know the factors effective oxidation and recovery of metals is in this environment.

Among the important factors affecting the particle size reduction potential at the electrode surface is metal and the deposition of these metals. For this reason, the behavior of these metals in ionic liquids should be studied well the potential and optimal recovery of metals deposition achieved in terms of time. Electrochemical synthesis of metal nanoparticles in the ionic liquid [HEMIM] [DCA] of two metal salts Fe (acac) 3 and Cu (SO) 4 were used. All samples with micro

Autolab and with three electrodes ( platinum working electrode diameter mm 2, the

reference electrode and platinum auxiliary electrode platinum wire ) voltammetry technique was studied . The first observations of hydrophilic ionic liquid solution in [HEMIM] [DCA] color crop production

Check salts of copper (II) sulfate in the ionic liquid [HEMIM] [DCA] :

0.25 ml of the solution of Cu (SO4) 2 concentration of 500 mg / l in ionic liquid [HEMIM] [DCA] was prepared as. The resulting solution of salt Cu (SO4) 2 is white to gray to ionic liquid yellow [HEMIM] [DCA] green was created for 5 minutes in the ultrasonic bath at 50 ° C to dissolve faster and uniform solution was . The electrodes are placed in the solution and the potential window 1.5- to 1 volt as the wheels ( the trip ) was scanned at 100 mV per second .

(Figure 2) copper salts in the experiment shows the cyclic voltammogram. Cu2 + in the potential of the Cu metal Reduced becomes vice versa and platinum electrode to the deposition time of 600 seconds in the shot that we see that the couple redox a and b are related to the conversion of Cu (II) to Cu ( 0 ) to increase scanning speed increases And the couple redox c and d on a Cu (II) to Cu (I) increase in severity during the courier were not observed , therefore, argues that the conversion reaction of Cu (II) to Cu (I) in the ionic liquid [HEMIM] [DCA ] is the slow kinetics toward a negative potential ( anode ) is.

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Figure 3 Differential voltammogram salt dissolved copper (II) sulphate at a concentration of 500 ml ionic liquid [HEMIM] [DCA] In the platinum electrode (cathode scan)

Figure 4 nanoparticles DLS whole Cu (SO) 4 in ionic liquid [HEMIM] [DCA] the potential- 0.5 V without shelf

Figure 5. SEM image of nano 4Cu (SO) in the ionic liquid [HEMIM] [DCA]

Check salt iron (III) acetyl acetone in the ionic liquid [HEMIM] [DCA]:

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Figure 6 Change the color of the salt Fe (acac) 3 after being dissolved in the ionic liquid [HEMIM] [DCA]

Figure 7 shows the cyclic voltammogram salt dissolved iron (III) acetyl acetone with a concentration of 500 mg per liter in the ionic liquid [HEMIM] [DCA] in the platinum electrode.

In examining the square wave voltammetry and in order to reduce peak in Figure 8 to convert iron (III) to Fe (II) , but the courier turned up iron (II) to Fe (I) is a short peak Similarly, peak square wave voltammetry Rehabilitation iron (III) to Fe (II) v 0.35- and conditions at the time of deposition of 900 seconds showed a lack of full recovery of Fe (III) to Fe metal (Fe0) is. ( Figure 8 ) at the time of deposition in 3600 ( Figure 9) with a thin film of metal nanoparticles potential V 1.5- iron deposition at the electrode surface formed by DLS spectral analysis and electron microscope images show the appearance of the metal nanoparticles that in the ionic liquid [HEMIM] [DCA] has grown

Figure 8 square wave voltammogram salt soluble iron (III) acetyl acetone with a concentration of 500 mg per liter in the ionic liquid [HEMIM] [DCA] in the platinum electrode deposition technique and time of 900 seconds

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Figure 10 DLS spectrum of nanoparticles Fe (acac) 3 in the ionic liquid [HEMIM] [DCA] the potential -0.5 V and without shelf

Figure 11. SEM image of Nano Fe (acac) 3 in the ionic liquid [HEMIM] [DCA]

The two conducted in ionic liquid synthesis [HEMIM] [DCA], shows that Cu (SO4) of Fe (acac) 3 is better. As part of the experimental design for ionic liquids [HEMIM] [DCA] and [EMIM] [NTf2] and two metal salts in the previous section was about 18 tests designed to synthesize different conditions than Scavenger dose concentration H2S, and the reaction temperature contact time, according to table 5 conducted and the results of the call arrived.

Table 5. The results of its experimental design for the ionic liquid [HEMIM] [DCA]

std run [IL] / [ H2S] TEMP TIME Response

Cu(SO4)2

Response Fe(acac)3

5 1 2 25 45 805 861

13 2 6 37/5 15 906 1004

3 3 2 50 15 813 1030

11 4 6 25 30 728 892

4 5 10 50 15 757 999

1 6 2 25 15 916 1001

6 7 10 25 45 662 759

16 8 6 37/5 30 830 874

12 9 6 50 30 718 919

17 10 6 37/5 30 701 891

18 11 6 37/5 30 705 836

2 12 10 25 15 755 988

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14 14 6 37/5 45 793 797

15 15 6 37/5 30 710 880

7 16 2 50 45 706 876

8 17 10 50 45 689 763

9 18 2 37/5 30 731 944

The results of the ionic liquid [HEMIM] [DCA] containing metallic nanoparticles Cu (SO4) synthesized. The time it takes to study the potential of crude oil began to decline in the nanoparticle Cu (SO4) 3 minute.

Table 6. Analysis of variance (ANOVA) model derived from experimental data Quadrativ ionic liquid [HEMIM] [DCA] Metal nanoparticles containing Cu (SO4)

Models Sum of squares df Mean square F value p-value probe>F

B-TEMP 3348.9 1 3348.9 1.628736316 0.2377 not significant

AC 406.125 1 406.125 0.197518748 0.6685 not significant

C^2 21901.96006 1 21901.96006 10.65201044 0.0115 significant

Residual 16449.07143 8 2056.133928

Pure Error 11697 3 3899

Cor Total 88473.77778 17

As Table 6 shows the amount of F model of the main factors in order of time and dose has the most effect, and the two factors AB effect and sentences curved other than C2 all unimportant, and the results show the importance of the first factor is time and dose then in C2.

After eliminating non-critical and non- influential factors Table 7 shows the result of the increased value of F model is effective with other sentences.

Table 7 ANOVA Kvadratyv model obtained from the experimental data after the adaptability of this ionic liquid [HEMIM] [DCA] Metal nanoparticles containing Cu (SO4) 2

Models Sum of squares df Mean square F value p-value probe>F

A-[S]/[H2S] 15288.1 1 15288.1 5.6653917 0.0321 Significant

C-TIME 24206.4 1 24206.4 8.9702931 0.0096 Significant

C^2 11200.17778 1 11200.17778 4.1505088 0.0610 Significant

Residual 37779.1 14 2698.507143

Lack of Fit 26082.1 11 2371.1 0.6081303 0.7641 not

significant

Pure Error 11697 3 3899

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As the graph in Figure 11 shows a higher dose is more effective in the process of reducing the potential and the graph is of little slope.Chart A and Chart B is the same as the temperature increases further potential declines, Chart C for descending and the optimal time . It is 30 times less than the slope of the graph is more. The trend of F in the ANOVA with the gradient changes to the same factors that represent the importance of each of the factors.

A

B

C

A) , temperature ( B ) and time (c ) for the ionic liquid shows the effect of three varying doses of (

Figure 11

[HEMIM] [DCA] containing nanoparticle Cu (SO4) 2

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Table 8 compares all types of models for the adaptability of data obtained from ionic liquid [HEMIM] [DCA] Metal nanoparticles containing Fe (acac) 3

Models Sum of

squares df Mean square F value p-value probe>F

Mean vs Total 14531440.5 1 14531440.5

Linear vs Mean 105960.7843 3 35320.26144 48.90205337 < 0.0001 Suggested

2FI vs Linear 3807.820713 3 1269.273571 2.214822636 0.1437

Quadratic vs 2FI 2980.337115 3 993.4457051 2.391282469 0.1442

Cubic vs Quadratic 367.914903 4 91.97872575 0.124478805 0.9660 Aliased

Residual 2955.642955 4 738.9107388

Total 14647513 18 813750.7222

Table 8 was observed between the proposed model is the model that best and highest value of F is linear

Table 9 Analysis of variance (ANOVA) of the linear model derived from experimental data ionic liquid [HEMIM] [DCA] Metal nanoparticles containing Fe (acac) 3

Model 112748.9421 9 12527.66024 30.15482 < 0.0001 significant

B-TEMP 739.6 1 739.6 1.780261 0.2188 not significant

C-TIME 93347.63166 1 93347.63166 224.6933 < 0.0001 significant

AC 3655.125 1 3655.125 8.798102 0.0180 significant

C^2 190.8698157 1 190.8698157 0.459435 0.5170 not significant

Residual 3323.557858 8 415.4447323

Pure Error 1712.75 3 570.9166667

Cor Total 116072.5 17

Shown in Table 9 is the highest value of F of the main factors dose and then eventually time temperature ( low impact ) is effectively between the two factors of effective dose and other factors Scavenger to H2S and time is ineffective the F, LOF is very low and ineffective .

Table 10 ANOVA linear model derived from experimental data after the adaptability of this ionic liquid [HEMIM] [DCA] Metal nanoparticles containing Fe (acac) 3

squares df Mean square F value p-value probe>F

Model 109615.9093 4 27403.97733 55.17644258 < 0.0001 significant

C-TIME 93315.6 1 93315.6 187.8859694 < 0.0001 significant

AC 3655.125 1 3655.125 7.359398684 0.0178 significant

Residual 6456.590687 13 496.660822

Lack of Fit 4743.840687 10 474.3840687 0.830916483 0.6420 not

significant

Pure Error 1712.75 3 570.9166667

Cor Total 116072.5 17

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A diagram is shown in Figure 12 that at low doses , and the plot has many steep increase this ratio is less steep and this indicates that by increasing the dose increases the reduction of H2S from oil.In Chart B shows the temperature influence on the reduction potential is not linear and is optimal temperature 37/5 ° C. The diagram shows that as the downside is steep and the ability to reduce potential down time is very weak and the time to increase the rate of decline increases. Charts have a direct relationship with ANOVA table's show the most effective factor in the ionic liquid [HEMIM] [DCA] nanoparticles containing Fe (acac) 3 is the time factor.

A

B

C

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In Figure 13 as a three-dimensional interaction of two factors dose and time is shown. The time factor can be said about the time a substantial decrease in H2S at low doses, and that downward trend continued up to the maximum amount of time, but by increasing the dose of the initial amount of H2S concentration is less than about 2. Less steep downward trend is observed with increasing time. Check this chart to another such that if operating conditions are such that there is no possibility to change the amount of time at the lowest dose level will decrease with time factor is very strong on the concentration of H2S However, when the maximum amount of time (45 minutes) is, increasing the dose does not have any effect on the concentration of H2S .

Figure 13 three-dimensional curve (procedurecall) for two- factor effect of dose and temperature for the ionic liquid [HEMIM] [DCA] Metal nanoparticles containing Fe (acac) 3.

DISCUSSION AND CONCLUSION:

1 - After the performance [HEMIM] [DCA] and a metal salt of copper include Cu (SO4) and an iron salts include Fe (acac) 3 to the effectiveness and strengthen the use of ionic liquid alternative for many Scavengers business in terms of environmental hazards and their use has been limited toxicity suggests.

2 - Ionic liquids containing nanoparticles effectively studied in ionic liquids without the nanoparticles have had a better performance in terms of time and amount of this effect appears to be due to the strengthening of liquidity Qurdine H2S and other sulfur compounds with metal nanoparticles is style.

3 - Copper metallic nanoparticles of the metal nanoparticles of iron under the same experimental conditions show better efficacy in reducing H2S.

4 - All nanoparticles studied the electrochemical deposition of metals are available and for the synthesis of nanoparticles is very simple and does not require advanced equipment and production of nanoparticles with

high purity and narrow particle size distribution of nanoparticles is important all the benefits. 5 - Studies have shown that the reduction potential and deposition time are all essential factors in the studies of electrochemical method is the production of metal nanoparticles

6 - No need for chemical and process equipment including benefits Scavenger injection method is also easy injection in tanks and pipelines is another advantage to this method can be said desulfurization.

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