Parametric Study for Upgrading Petroleum Vacuum Residue Using

Subscriber access provided by SETON HALL UNIV

Article

Parametric study for upgrading petroleum vacuum residue using supercritical m-xylene and n-dodecane solvents Doo-Wook Kim, Fanzhong Ma, Anton Koriakin, Soon-Young Jeong, and Chang-Ha Lee Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.5b00115 • Publication Date (Web): 23 Mar 2015 Downloaded from http://pubs.acs.org on March 27, 2015

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Energy & Fuels is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Parametric study for upgrading petroleum vacuum residue using supercritical m-xylene and n-dodecane solvents Doo-Wook Kima, Fanzhong Maa, Anton Koriakina, Soon-Yong Jeongb and Chang-Ha Leea,* a

Department of Chemical and Biomolecular Engineering, Yonsei University, Republic of Korea

b

Research Center for Green Catalysis, Korea Research Institute of Chemical Technology,

Republic of Korea Keywords: Upgrading; Vacuum residue; Supercritical solvent; Activated carbon; Polar component

ACS Paragon Plus Environment

1

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 33

Abstract

The upgrading of petroleum vacuum residue was conducted with activated carbon (AC)-based catalysts in sub- and supercritical m-xylene and n-dodecane. The conversion, liquid yield, coke formation, sulfur removal and the product distribution were evaluated at various reaction conditions; different kinds of AC catalysts, temperatures (350-400°C), H2 pressures (0.50-3.45 MPa), reaction times (5-30 min) and polar components (H2O, methanol, and ethanol in solution). The acid-treated bituminous coal-derived AC produced the highest liquid yield of 76.0 wt% in supercritical m-xylene and 84.4 wt% in supercritical n-dodecane, while it also obtained the lowest coke formation of 16.3 wt% in supercritical m-xylene and 8.4 wt% in supercritical ndodecane. When compared to the coconut shell-derived AC catalyst, its acid-treated catalyst resulted in higher conversion but lower liquid yield due to the high degree of coke formation. Furthermore, the influence of reaction temperature on the upgrading reaction was more profound in both solvent systems than that of hydrogen pressure and reaction time. Regardless of the type of polar component in solution, reduced liquid yield and increased coke formation were observed. The supercritical solvents led to significant improvement in both conversion and liquid yield, as well as reduced coke generation when compared to the subcritical solvents. While surface acidity was an important factor for conversion, coke formation and liquid yield were significantly affected by the type of AC catalyst and a polar component in solution.


2

Page 3 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

1.

Introduction

Petroleum industries have been forced to refine heavy feedstocks such as oil sands, bitumen, and heavy residues in conventional refining processes due to the depletion of light crude oils and rising demand for valuable petroleum products.1-3 Among the heavy feedstocks, petroleum vacuum residue (VR) with high boiling points over 520°C represents the heaviest fraction obtained by processing atmospheric residue (AR) in the vacuum distillation.3, 4 When used as a fraction of heavy furnace oil, VR is accountable for considerable environmental pollution because it contains about 5 wt% sulfur and 0.5 wt% nitrogen in the form of heterorganic compounds. Since heavy fractions make up about 25 wt% of the feed on average, refiners must solve the problem of increasing VR volumes.5 Heavy hydrocarbons can be converted into low-boiling point materials by either the rejection of carbon (e.g., thermal/catalytic coking) or the addition of hydrogen (e.g., hydrocracking processes).6 Compared to carbon-rejection processes, hydrocracking processes are conducted under milder conditions, thereby producing higher yields of liquid fractions.7 However, the high concentration of asphaltenes, sulfur, nitrogen, and metal-containing compounds poses a significant problem in hydrocracking processes due to the deactivation of conventional catalysts by the deposition of coke and metals.1, 8-13 Consequently, research has been devoted to improving the resistance of catalysts to deactivation so as to prolong their operational lifespan.14, 15 A possibility was suggested that activated carbons could be used as hydroprocessing catalysts. It was reported that hydrocarbon/carbon systems can be readily used and can act as a more powerful hydrogen donor than the hydrocarbon solvent alone in the reduction/hydrogenation reaction.16 In case of heavy oil feeds, the micropores in catalysts can contribute to the reaction of smaller molecules derived from cracked asphaltenes but these pores become less available with


3

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 4 of 33

time by coking and plugging.8, 14 A study of catalyst pore structure has also confirmed the computed patterns of deposits in various pores where the slopes of the deposit curves for coking and plugging near the pore mouths are steep in small pores and the contraction of the pore mouths is rapid.17 Other studies have shown that mesopores in the activated carbons play crucial roles in improving the conversion and prevent coke formation in VR upgrading reaction.8, 18, 19 It was concluded that pores having smaller size cannot be utilized effectively and catalysts with pore diameters of larger than 20 nm are needed for hydroprocessing of VR because VR contains a large aggregate and cluster of asphaltene molecules.14 However, catalysts with large pores have lower crushing strength and are less active because of a decrease in the number of active sites. The self-assembly step of asphaltenes highly depends on concentration, source of the asphaltenes, presence of resin, solvent power, and physical environment.20 If aromatic or long paraffinic hydrocarbon is used as a solvent, it can make asphaltene micelles smaller than those obtained without solvents. It was also pointed out that the AC catalyst can reduce polycondensation reactions in the hydrocracking reaction of VR.18 Therefore, various studies have shown great interest in carbon as a catalyst or catalyst support for the hydroprocessing of heavy oils due to its excellent textual properties, surface functional groups, and high resistance to coke deposition.21-23 However, since VR can still cause blockage and coking of the micropores in AC catalysts, a compromise on pore size distributions should be found for the VR-SUP using various AC catalysts, which is related to low diffusional resistances and high activity. The reaction media and operating conditions also play crucial roles in conversion from hydroprocessing. When a fluid phase changes from the subcritical to supercritical condition, the reaction mechanisms change significantly because of the large difference in physical and chemical properties.24, 25 In other words, supercritical fluids as reaction media can increase the


4

Page 5 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

diffusion rate in the pore-mouths of catalysts and, hence, minimize mass-transfer limitations.26-30 It was also reported that the supercritical hydrocarbon solvent would reduce the mesophase known to be the precursors of coke31, stabilize asphaltene species, prevent further aggregation into clusters32, and improve hydrogen gas solubility.33 Furthermore, a paraffin-rich hydrocarbon with activated carbon could induce a synergistic effect when gaseous hydrogen is also present. Namely, the activated carbon with hydrogen gas would serve to re-saturate the hydrocarbon, leading to the transfer of hydrogen from the hydrocarbon/hydrogen phase to heavy oil molecules.18, 34 Recent studies showed that supercritical hydrocarbons contributed to the high conversion of VR to light oil products in the upgrading process, and activated carbon would serve as a good catalyst in the reaction.3, 8 To select a proper solvent in the process, a few criteria are needed: (1) high solubility of heavy fractions such as asphaltene micelles in vacuum residue and reduced viscosity of feedstock mixture; (2) a moderate critical point of solvent at the condition of applicable temperature and pressure to the real field; (3) an easily accessible and relatively cheap solvent in petrochemical industry. When four kinds of supercritical solvents (aromatic hydrocarbons: m-xylene and toluene, normal alkanes: n-hexane and n-dodecane) were applied to the previous study, the conversion efficiency of n-docecane and m-xylene was better than the others.3 The solvent with a low boiling point like n-hexane is insoluble with asphaltene, while ndodecane with a high boiling point and aromatic hydrocarbons is soluble with asphaltene. The upgrading process of the vacuum residue is one of the complicated reactions because complex reactants go into various reactions taking place simultaneously. Furthermore, the physical and transport properties of the supercritical upgrading process could be rigorously changed near the critical condition. The reaction performance using a solvent could be strongly


5

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 6 of 33

influenced by various factors like its critical points, solubility of heavy components, ability to transfer hydrogen, steric hindrance, density, transport property and so on. As a result, the reaction performance such as conversion, product distribution and coke formation could be quite varied according to each operating condition. In addition, because the feedstock would contain certain levels of polar components in a real process, it is also important to study the effect of such minor impurities on the reaction. Naturally, the reaction sensitivity of the SUP has to be evaluated by changing the operating conditions and it can offer a keen insight into the upgrading reaction for extra heavy oils. Although the supercritical solvent with activated carbon plays an important role in the conversion of VR, little attention has been paid to the parametric study in upgrading VR. The objective of this study is to achieve high conversion of vacuum residue to light hydrocarbons with reduced coke formation in the supercritical upgrading process (SUP). The performance of the supercritical upgrading process for VR (VR-SUP) could be affected by both the type of carbon catalyst and the operating conditions because the coke formation was sensitively affected by reaction temperature and duration. Due to the significant effect of the reaction condition on the VR-SUP, a parametric study was carried out in a batch reactor using mxylene and n-dodecane solvents in the study. The bituminous coal-derived and coconut shellderived activated carbons were selected as a base catalyst because they are popular activated carbons with a reasonable cost. Here, additional modified activated carbons (acid-treated catalysts and Fe-impregnated catalyst) were also applied to the VR-SUP. The results were obtained and then compared at various temperatures (350°C, 380°C, and 400°C), hydrogen partial pressures (0.50 MPa, 1.38 MPa, and 3.45 MPa), and reaction times (5 min, 10 min, and 30 min). The effects of a polar component (H2O, methanol, and ethanol) in solution on the VR-


6

Page 7 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

SUP were also investigated. The parametric results of the VR-SUP were evaluated in terms of conversion, liquid yield, coke formation, and the product distribution (light oil products, vacuum gas oil, and residue). The level of sulfur removal and the asphaltenes fraction of liquid products were analyzed. The experimental analysis of the VR-SUP reaction at various operating conditions contributes to the in-depth understanding of the complex upgrading system for heavy oils.

2. Experimental section 2.1. Materials The feedstock was real vacuum residue from distilled vacuum units (DVU-VR), which was supplied by an oil refinery. The viscous DVU-VR (3,580 cSt at 100°C) contained more than 23.03 wt% of Conradson carbon residue and only up to 62.6 wt% could be recovered at 750°C. It had only 5.8 wt% of vacuum gas oil fraction without naphtha and middle distillate fractions. Furthermore, the DVU-VR contained large amounts of pitch (96 wt%: Conradson carbon residue 23.03 wt%) , sulfur (5.32 wt%), nitrogen (0.29 wt%), and metals (about 170 wppm). The properties and distillation cut point of the DVU-VR are presented in Table 1. Bituminous coal-derived activated carbon (B; Calgon Filtrasorb 300, Calgon Carbon Corporation) and coconut shell-derived activated carbon (C; Pellet 4GS, Kuraray Co. Ltd.) were used in this study. Both catalysts were modified by sulfuric acid (96 wt%) at 250°C for 3 h so as to increase both the concentration of surface functional groups and the pore size (catalysts BA and CA). After the samples were washed thoroughly with double-distilled water until the filtrated water was free of sulfate (tested with BaCl2), they were dried overnight at 120°C. The activated carbon with the iron oxide could contribute to the improved conversion.8, 35 In the


7

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 8 of 33

study, iron salt (Fe(NO3)3·9H2O) was first dissolved in 100 mL of water that was placed in contact with the catalyst BA to verify the effect of Fe impregnated activated carbon on VR conversion. After drying the sample at 80°C, calcination was then conducted at 300°C for 3 h in a tubular furnace (BA-Fe). Before the reaction, Fe catalyst was activated in situ, using a mixture of hydrogen and hydrogen sulfide made from feedstock at 380°C. Abbreviation descriptions of the activated carbon catalysts employed in this work are provided in Table 1. In this study, n-dodecane and m-xylene (Sigma-Aldrich, HPLC-grade) were selected as representative organic solvents of normal alkanes and aromatic hydrocarbons. The critical conditions of n-dodecane and m-xylene are 385.2°C/1.8 MPa and 344.2°C/3.5 MPa, respectively. It was reported that the critical points of reaction mixtures change with time because of their chemical composition changes.36 Since the complexity of phase diagram increases with the number of components in the mixture, it was hard to define the critical condition with time during the VR-SUP. In the study, the reaction condition was described as a supercritical condition on the basis of the critical point of each solvent such as supercritical solvent, supercritical m-xylene, and supercritical n-dodecane.

2.2. Apparatus and methods All experiments were performed in a laboratory-scale batch reactor composed of a nickelbased alloy (Inconel 625; 200 mL volume) and equipped with an agitator in Fig. 1. The catalysts were supplied in four spinning baskets that were installed on the impeller shaft in order to improve contact efficiency without destruction of the catalyst by impeller rotation.


8

Page 9 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

The reactor temperature was measured by the thermocouple in the middle of reactor and could be controlled using the PID temperature controller within ±2.5°C. The reaction pressure was measured by both a pressure gauge and pressure transducer. After 5 g of the DVU-VR was mixed with 40 ml of solvent, 8 g of the catalyst in the spinning catalyst baskets was loaded into the reactor. The reactor was then purged several times with nitrogen gas to remove air and heated at a rate of 15°C/min by an electrical furnace. Fig. 1 shows the representative temperature and pressure profiles with respect to the reaction time during an experimental run. To minimize VR upgrading reaction before reaching the desired temperature, hydrogen was fed into the reactor when the reaction temperature was 20 degrees below the desired temperature. The reactor was then heated to 400 °C, at which point recording of the reaction time began. After reaction, the reactor was quenched in a cold water bath. The collected solids were washed with toluene by the Soxhlet method to extract oils. Then, the mass of the dried solids was measured to calculate the total quantity of coke. In the experiments with a polar component (H2O, methanol, or ethanol) in solution, 10 wt% of the component (based on the mass of the VR) was loaded into the reactor, and the corresponding amount of solvent was subtracted from the solution. In the study, the system pressures were measured before and after the reactions, respectively. The pressure change was less than 0.07 MPa, and it accounted for less than 0.8 wt% in product distribution. The result agreed with the previous studies of the upgrading for heavy feedstock, which have shown a small amount of gas production in the range of 0.5 wt% and 3 wt% at similar operating conditions.34, 37 Since it was lower than the experimental error range, it was ignored in the study. As shown in Fig. 2, the liquid product was analyzed by simulated distillation (SIMDIS) gas chromatography according to the American Society for Testing


9

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 10 of 33

Materials (ASTM) protocol (SIMDIS ASTM7213A-7890). In addition, the experiment for a pure solvent without DVU-VR was conducted at each experimental condition and the resulting solution was analyzed separately; these were referred to as baseline experiments. At a specific boiling point, the recovered mass% of pure solvent and liquid product could be obtained from each boiling point distribution (SIMDIS result) for baseline and standard experiments. Therefore, the final mass of oil product was calculated by subtracting the mass of pure solvent from the mass of liquid product at specific boiling point. Using this method, the oil products can be classified into four fractions: naphtha (IBP-177°C), middle distillate (177-343°C), vacuum gas oil (343-525°C), and residue (>525°C). Since the recovered mass% of solvent fraction at 177°C (boundary temperature between naphtha and middle distillate) showed a variation of 0-3 wt% in the SIMDIS analysis, some deviation was generated in the calculation of the naphtha and middle distillate fractions because of the dilution ratio of DVU-VR to solvent. Therefore, the fractions of naphtha and middle distillate were combined and presented herein as the fraction of light oil products. The yield (wt% of DVU-VR fed) of each fraction, the amount of coke, the conversion including coke, and the liquid yield were obtained by Equations (1)-(6).

(

(

(

( )

(

)

)

)

)


10

Page 11 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

The asphaltenes fraction and sulfur content of the liquid product were analyzed by thin-layer chromatography (TLC) with flame ionization detection (FID) (IATROSCAN MK-6s) and a sulfur analyzer (Sindie 7039 XR, XOS), respectively. The N2 adsorption/desorption isotherms (Quantachrome instrument Autosorb iQ, version 3.0 analyzer) for the catalysts were measured for a physical property analysis, while the surface acidity was determined using the classical Boehm titration method. The physical and surface properties of the activated carbon catalysts are presented in Table 1. In this study, independent experiments were repeated at least two times under the same conditions to determine the reliability in all the experimental results. The experimental deviation in conversion and product yield was in the range of ±1%.

3.

RESULTS AND DISCUSSION

3.1. Effects of different types of catalysts Since the VR dissolved in m-xylene or n-dodecane was used, it was expected that the molecules were well dispersed in the solution. In addition, the carbon catalyst has high selectivity for the cleavage of alkylene bridges between naphthyl moieties and makes it possible to break the bond at lower temperature than the thermal reaction.22 Therefore, the decomposed molecules are more likely to react continuously in the meso/micropores of activated carbon catalysts.


11

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 12 of 33

To investigate the effect of the catalysts on the VR-SUP reaction, five types of AC catalysts in Table 1 were used in the experiments. The surface area of catalyst C was larger than that of catalyst B, and the mesopores in catalyst C were relatively well developed. The surface acidity for both activated carbons modified by acid (BA and CA) increased by approximately 12 to 15 times over that of the raw activated carbons (B and C), while the basicity became negligible. The surface acidity of BA-Fe was similar to that of acid-treated AC (BA), but its surface area was lowest. The effects of the catalysts on the conversion, liquid yield, coke formation, and product distribution in the VR-SUP are presented in Table 2 and Fig. 3. Modified AC (BA) was characterized by an increase in surface area, pore volume, and surface acidity compared to AC (B). In the case of catalyst BA, the liquid yield (76.0 wt% and 84.4 wt% in supercritical mxylene and n-dodecane, respectively) and conversion improved in both solvents when compared to those from catalyst B, as shown in Table 2. The improvement in the liquid yield was higher in n-dodecane than in m-xylene, and the conversion which includes coke as a product reached 93.3 wt% in both solvents. The amounts of coke from catalysts B and BA were almost the same in supercritical m-xylene, while the quantity of coke was reduced when using catalyst BA in supercritical n-dodecane. Different trends were observed in the results obtained from catalysts C and CA. As shown in Table 1, the treatment of catalyst C by sulfuric acid (catalyst CA) led to a decrease in surface area, mesopore area, and diameter. In supercritical m-xylene, the conversion increased from 93.3 wt% to 96.4 wt% when catalyst C was replaced by acid-treated catalyst CA. However, the liquid yield of the SUP reaction was reduced by 8.7 wt% because the total coke amount increased from 19.2 wt% to 30.3 wt%. In other words, the DVU-VR, which contains large-sized molecules, was


12

Page 13 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

well-decomposed by improving surface acidity on coconut shell-derived activated carbon (CA). On the other hand, the liquid yield in the SUP reaction was reduced because excessive activation led to the generation of a larger quantity of coke. Similar results were observed for the case of supercritical n-dodecane using catalyst CA in Table 2. The liquid yield decreased from 71.5 wt% to 62.0 wt% because the total coke amount increased from 20.6 wt% to 33.5 wt%. It was expected that a decrease in both the mesopore area and diameter would have a negative effect on the VR-SUP while an increase in surface acidity would have a positive effect on the cracking reaction.38 However, the effect of surface acidity seemed to be a more important factor on the VR-SUP because it was more related to conversion and coke formation than the change of the mesopore area and diameter. When comparing the yield of each fraction in Fig. 3, it is evident that an increase in surface acidity for coal-derived activated carbon (BA) led to an improvement in the yield of light oil products in supercritical m-xylene. Increases in surface acidity, surface area, and mesopore area may provide more acidic sites on the catalyst. However, compared to catalyst C, the increase in coke formation for catalyst CA was significant, and a small decrease in light oil products was observed. In Fig. 3, the changes in light oil products and coke formation in supercritical ndodecane were similar to those in supercritical m-xylene when the fresh catalysts were replaced by acid-treated catalysts in the SUP. The VR-SUP reaction without any catalyst in m-xylene converted the DVU-VR into light oil products of 16 wt%, vacuum gas oil of 33.9 wt% and coke formation of 16.3 wt% at 3.45 MPa H2 and 400°C. It implied that the addition of activated carbon to reaction could lead to increased light oil products and conversion. From the results, it would appear that, in order to obtain a larger quantity of light oil products/liquid yield and suppress coke formation, the selection of raw


13

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 14 of 33

activated carbon would be an important factor. While the surface acidity of activated carbon played a key role in VR cracking, it could also simultaneously accelerate coke formation. In the study, activated carbon with dispersed iron oxide (BA-Fe) was prepared because catalyst BA showed better performance than catalyst CA in Table 2. It was expected that the active phase of iron oxide may lead to improved hydrogen dissociation and the carbon support would become the main reservoir of hydrogen atoms.39 The mesopore area of catalyst BA-Fe increased from 214 m2/g to 297 m2/g, while the BET surface area was greatly reduced. The total acidity was lowest among the acid-treated catalysts, but the difference was not significant. Compared to the results acquired from catalyst BA, the conversion using catalyst BA-Fe was similar but the liquid yield was significantly reduced because of a large amount of coke generation in both supercritical m-xylene and n-dodecane. Furthermore, the light oil products were worse than those from catalyst BA as shown in Fig. 3. While the liquid yield from catalyst BA-Fe was similar to that from catalyst B, catalyst BA-Fe produced more light oil products and lower fractions of vacuum gas oil and residue in both supercritical solvents than catalyst B. In the study, another series of analyses were conducted to identify the sulfur removal and asphaltenes conversion in the SUP reaction for catalyst BA, showing more liquid yield and less coke formation in Table 2. The solution with 5g of the DVU-VR contained 6,451 ppm of sulfur compounds on average. The fraction of asphaltenes accounted for 48.6 wt% and 55.3 wt% in mxylene and n-dodecane solution, respectively, as solubility of asphaltenes is different in each solvent. After the reaction using catalyst BA at 400oC, the sulfur removal was 77.5 wt% for mxylene and 85.1 wt% for n-dodecane. Additional sulfur analysis was carried out for the samples from the VR-SUP reaction using catalyst BA-Fe because the synergistic effect was expected from the transition metal and activated carbon. However, a similar conversion and a lower liquid


14

Page 15 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

yield were achieved from catalyst BA-Fe as shown in Table 2. The sulfur removal was improved from 77.5 wt% to 93.6 wt% in the m-xylene system and from 85.1 wt% to 96.4 wt% in the ndodecane system by using catalyst BA-Fe, and the content of asphaltenes was not observed in the solution by using catalyst BA or BA-Fe. It was reported that the sulfur compounds of about 77% are originally present in the asphaltenes as the type of reactive moieties (e.g., thioether) or refractory moieties (e.g., heterocyclic thiophene).40 It is difficult to remove certain levels of the sulfur compounds located in refractory moieties because these are resistant to thermal reaction. However, when catalyst BA or BA-Fe was used in SUP reaction, a certain amount of refractory sulfur compounds in asphaltenes could be eliminated from the solution by the adsorption on the catalyst and then deactivate the catalyst as a form of sulfur containing coke. Therefore, a high deposit of refractory sulfur compounds could lead to catalyst deactivation and reduce liquid yield in VR-SUP reaction. 3.2. Effects of reaction temperature The effects of reaction temperatures (350, 380, and 400°C) on conversion, liquid yield, coke formation, and the yield of oil products were examined with catalyst BA in both solvents at a hydrogen pressure of 3.45 MPa. As shown in Table 3, the conversion/liquid yield increased from 73.5 wt%/56.3 wt% at 350°C to 87.3 wt%/66.8 wt% at 380°C, and then to 93.3 wt%/84.4 wt% at 400°C when n-dodecane was changed from a subcritical to supercritical condition (critical point: 385.2°C, 1.8 MPa). The liquid yield was significantly improved and coke formation was suppressed at the supercritical ndodecane condition. The reaction temperature had a huge impact on the conversion of residue into liquid products because a high temperature leads to improved thermal cracking without a significant change in the reaction pressure. The total coke amount was not directly proportional


15

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 16 of 33

to temperature, as the largest quantity of coke was obtained at 380°C in both solvent systems. With respect to the critical point of each pure solvent, this temperature was only 5°C lower than the critical temperature (385.2°C) of n-dodecane and was above the critical temperature of mxylene. Since the critical point can be changed with reaction time as mentioned before, it is difficult to identify the critical condition of the multicomponent reaction system. It implied that it was not practical to define the reaction phase condition as a near-critical or far from critical condition by using the critical condition of a pure solvent. As shown in Fig. 4, the coke formation was suppressed with lower fraction of residue when the reaction temperature increased from 380°C to 400°C. It was reported that the unique combinations of liquid-like density and gas-like diffusivity near critical points could inhibit catalyst deactivation by coke formation and maintain catalyst activity.41 Therefore, it was presumed that the critical temperature of the reaction mixture might be moved to a higher temperature than that of a pure solvent and this condition could sensitively change the physical and transport properties for the better. To more clearly elucidate the effect of temperature on VR-SUP, further study is needed for the phase diagram of the VR/solvent system in high temperature and high pressure. In the case of m-xylene, all experiments were conducted in the supercritical condition of mxylene (critical point: 344.2°C, 3.5 MPa). When the temperature was increased from 350°C to 380°C, the conversion increased, but the difference in the liquid yield was small because the total coke amount also increased, as shown in Table 4. On the other hand, when compared to the results acquired at 380°C, the conversion (93.3 wt%) and liquid yield (76.0 wt%) were found to increase significantly at 400°C, but the total coke (16.3%) was reduced.


16

Page 17 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

The product distribution of the VR-SUP reaction with catalyst BA at the corresponding conditions in Tables 3 and 4 is presented in Fig. 4. With an increase in temperature, the residue fraction decreased in both solvent systems and the fraction of light oil products increased in ndodecane. On the other hand, the yield of light oil products was smallest at 380°C in supercritical m-xylene even though the liquid yield was similar to that obtained at 350°C. 3.3. Effects of hydrogen partial pressure It was reported that it is important to choose an appropriate hydrogen pressure in hydrocracking vacuum residues because too high hydrogen pressure leads to decreased conversion by the secondary reactions of cracking products (polymerization, alkylation, hydrogenation)4, 5 and slow reaction kinetic due to relatively low VR concentration.42 Here, the effects of a decrease in hydrogen partial pressure (0.50 MPa, 1.38 MPa, and 3.45 MPa) on the VR-SUP were investigated at a reaction temperature of 400°C with catalyst BA in both solvents; the results are presented in Tables 3-4 and Fig. 5. The conversion and liquid yield were highest in n-dodecane when the H2 partial pressure was 0.50 MPa in Table 3. The conversion then decreased with an increase in the H2 partial pressure, but the coke formation was reduced only at a hydrogen pressure of 3.45 MPa. It was noted that the H2 partial pressure did not produce a significant change in the yield of light oil products in ndodecane as shown in Fig. 5. The effects of the hydrogen partial pressure on the VR-SUP in mxylene were different from those in n-dodecane. From Table 4, the highest conversion and lowest liquid yield were observed at 0.50 H2 MPa. In Fig. 5, the fraction of residue was mainly converted into a large amount of coke at a low H2 partial pressure condition, which resulted in a low fraction of light oil products.


17

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 18 of 33

Coke formation is a consequence of precipitation and accumulation of asphaltenes, which is related to the solubility of asphaltenes in a solvent and solvent ability to transfer hydrogen into asphaltenes. On the other hand, aromatic hydrocarbons or long chain n-alkanes can inhibit the aggregation of asphaltenes because asphaltenes dissolve readily in such solvents. Therefore, these solvents may delay or inhibit coke formation. However, the amount of coke increased significantly in m-xylene but remained more or less constant in n-dodecane at 0.50 H2 MPa, compared with the results at higher hydrogen pressure. It was expected that asphaltenes worked as the primary source of hydrogen and then were converted into coke in m-xylene while nparaffin solvent could act as a superior hydrogen donor. In addition, since coke was mainly deposited in catalysts, the effect of H2 pressure on the reaction may be limited after the coke formation at the surface and pores of catalysts. While the contribution of H2 pressure to the liquid yield and coke formation was not significant if a certain level of H2 pressure is provided, the product quality could be changed. The H2 pressure in the VR-SUP should be decided properly according to the purpose of the process, i.e., more light oil production or coke suppression. 3.4. Effects of reaction time The reaction time is an important technical and economic factor in the SUP reaction. If the reaction time is too short, the reaction would not be completed and the product quality cannot reach satisfactory level. However, when the time is too long, the condensation reaction would be enhanced and more carbon will be deposited on the catalyst surface, which is not desirable with respect to process efficiency and product quality. In this study, VR-SUP experiments for different reaction times (5 min, 10 min, and 30 min) were carried out with catalyst BA at a temperature of 400°C and a hydrogen pressure of 3.45 MPa.


18

Page 19 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

In Tables 3 and 4, the conversion was highest at the longest reaction time in both solvents. In addition, an increase in the reaction time from 5 to 30 min in supercritical n-dodecane led to an increase in the liquid yield from 76.5 wt% to 84.4 wt% and a decrease in coke formation from 14.3 wt% to 8.4 wt%. The variation of liquid yield and coke amount with reaction time in mxylene was different from that in n-dodecane. The liquid yield increased significantly from 62.3 wt% to 80.8 wt% as the reaction time was increased from 5 min to 10 min in supercritical mxylene, but it decreased to 76.0 wt% with a further extension in the reaction time. The variation in the coke amount showed an opposite trend when compared to the liquid yield change (25.5 wt% to 9.9 wt% to 16.3 wt%). It was reported that, during the initial coking, two kinds of coke species were formed rapidly on the catalysts.43, 44 The first is the soft coke composed of coke precursors such as asphaltenes and aromatics from the feedstock. A reactive soft coke is reversibly adsorbed at the catalyst and can be removed more easily. The second is the refractory coke that tends to be strongly adsorbed at the catalyst surface and its formation is catalyzed by acidic sites of the catalyst with reaction time. A higher amount of coke at a shorter reaction time (5 min) was observed in both solvents. That might be not enough time for supercritical solvents as reaction media to transport and extract soft coke which is coke precursors adsorbed on the catalyst. The mesophase known to the coke precursors such as aromatics, resins, and asphaltenes in the VR31, 32 could not be removed from the catalyst pores during the short reaction time. On the other hand, after being quenched in a cold water bath, the coke precursors could not be fully extracted from the catalyst by the Soxhlet method because of the deposit deep inside the micropores and pore blocking by coke. These coke precursors in the micropores of catalyst could be accounted for the coke fraction with real coke amount in VR-SUP.


19

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 20 of 33

In Fig. 6, the change of product distribution in n-dodecane was much smaller than that in mxylene, depending on the reaction time. One of the reasons for the difference in liquid yield, coke formation, and product distribution resulted from a near critical temperature reaction for ndodecane and a higher critical temperature reaction for m-xylene in the experimental condition. To summarize, in supercritical n-dodecane, a modest increase in the reaction time contributed to a suppression of coke formation and improvements in the conversion and liquid yield. However, supercritical m-xylene, which was employed at a higher critical condition, required a proper reaction time for high liquid yield and coke suppression. 3.5. Effects of polar component in solution In refinery processes, effluent stream can contain a certain level of polar component (water).45 In addition, it was reported that compressed or supercritical polar solvents such as water and alcohols could decompose biomass successfully.46, 47 In this study, the effects of different polar components (H2O, ethanol, and methanol) on the VR-SUP were investigated at a reaction temperature of 400°C, a hydrogen pressure of 3.45 MPa, and a reaction time of 30 min with catalyst BA in supercritical solvents (m-xylene or n-dodecane). At room temperature, a homogeneous solution was simply made by mixing m-xylene with ethanol or methanol. In contrast, it was difficult to obtain a homogenous mixture of m-xylene and H2O, as well as of n-dodecane and each of the components. Therefore, DVU-VR dissolved in a homogeneous or heterogeneous solution at room temperature was used to examine the effects of polar components on the VR-SUP. The conversion, liquid yield, and coke formation for the VR-SUP reaction in supercritical ndodecane and m-xylene are presented in Tables 3 and 4. Compared with the results obtained without a polar component, similar conversion, a lower liquid yield, and higher coke formation


20

Page 21 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

were observed in both solvents with the introduction of the components. It was noted that the severity of negative effects on the liquid yield and coke formation was independent of the type of polar component, but more significant in n-dodecane (about 10-11 wt% decrease in liquid yield and 8-11 wt% increase in coke formation) than in m-xylene (6-9 wt% decrease in liquid yield and 4-5 wt% increase in coke formation). Regardless of the kinds of polar components, the product distributions for the reactions with a polar component were similar in each solvent, as shown in Fig. 7. In addition, when compared to the reactions without the component in the solution, the fractions of light oil products and vacuum gas oil decreased. The results indicate that polar components serve as a reaction promoter for coke formation.

4.

Conclusions

The parametric study of a supercritical upgrading process for vacuum residue (VR-SUP) was carried out using m-xylene and n-dodecane solvents in a batch-type reactor. Since the VR-SUP could be affected by both the type of carbon catalyst and the operating conditions, the experimental performance was evaluated at various conditions. In the VR-SUP, the H2 partial pressure, reaction time, and reaction temperature should be optimized for high conversion/liquid yield or low coke formation in each solvent. In addition, the textural and surface properties of the activated carbon catalyst have a profound effect on the VR-SUP due to coke formation on catalyst. The acid-treated coal-derived activated carbon (BA) resulted in improved conversion/liquid yield and a suppression of coke formation in the VR-SUP. On the other hand, the acid-treated coconut shell-derived activated carbon with relatively well-developed mesopores (CA) increased


21

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 22 of 33

conversion while showing a decrease in the liquid yield and a significant increase in coke formation. DVU-VR could be well-decomposed by improving surface acidity on the catalyst. However, an increase in acidity could also lead to high coke formation due to the adsorption and fast reaction of asphaltenes on the catalyst. With an increase in reaction temperature, the conversion and liquid yield increased in both solvent systems. The supercritical condition of the solvent could lead to a high liquid yield compared to the subcritical condition. However, the product distribution (including coke fraction) was not directly proportional to the reaction temperature. As the hydrogen partial pressure reached a certain level, its contribution to VR-SUP was not particularly notable, but the product distribution could be changed. Certain reaction time was needed to suppress coke formation and improve the liquid yield. Supercritical n-dodecane required a longer reaction time than m-xylene to reach a certain level of liquid yield in the VR-SUP. Furthermore, an excessively long reaction time in m-xylene with a lower critical temperature resulted in an increase in coke formation and a decrease in the liquid yield. The polar components in both solvents led to a reduction in the liquid yield and a steep increase in coke formation while the total residue conversion was only slightly affected. Therefore, if VR contains a certain amount of polar compounds in VR-SUP, a larger quantity of coke can be generated in the reaction without a significant change in the total conversion.


22

Page 23 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Figure 1. Schematic of the high-pressure batch system with profiles of experimental temperature and pressure.

Figure 2. SIMDIS result at ASTM high temperature: VR-SUP with catalyst BA at 400°C and 3.45 MPa H2 partial pressure in supercritical m-xylene solvent.


23

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 24 of 33

Figure 3. Effect of the catalysts on the product yield distribution in the VR-SUP at a temperature of 400°C and H2 partial pressure of 3.45 MPa in (a) supercritical m-xylene and (b) supercritical n-dodecane (*: data from reference 3).

Figure 4. Effect of reaction temperature on the product yield distribution in the VR-SUP with catalyst BA at a 3.45 MPa H2 partial pressure: (*) reaction in n-dodecane, (**) reaction in mxylene.


24

Page 25 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Figure 5. Effect of the H2 partial pressure on the product yield distribution in the VR-SUP with catalyst BA at 400°C in supercritical solvents: (*) reaction in n-dodecane, (**) reaction in mxylene.

Figure 6. Effect of reaction time on the product yield distribution in the VR-SUP with catalyst BA at 400°C and a 3.45 MPa H2 partial pressure in supercritical solvents: (*) reaction in ndodecane, (**) reaction in m-xylene.


25

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 26 of 33

Figure 7. Effect of polar components (10 wt% based on the mass of VR) on the product yield distribution in the VR-SUP using catalyst BA at 400°C and a 3.45 MPa H2 partial pressure in supercritical solvents: (*) reaction in n-dodecane, (**) reaction in m-xylene.


26

Page 27 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Table 1. Properties of DVU -VR and catalysts. Properties of DVU-VR Conradson Carbon Residue (CCR), wt% S, wt% N, wt% Ni, wppm V, wppm Fe, wppm Viscosity, cSt ( at 100 °C)

23.03 5.32 0.29 38.4 104.2 23.2 3580

Recovered, wt% Cut point, wt% Naphtha Middle distillate Vacuum gas oil Residue

62.6 0.0 0.0 5.8 56.8

B*

BA

C

CA

BA-Fe

1025

1216

1075

1023

816

1056

1247

1408

1378

920

194

214

274

252

297

0.46

0.52

0.61

0.60

0.40

Mesopore volume - BJH Adsorption (cm /g)

0.23

0.29

0.28

0.26

0.27

Mean micropore diameter (nm)

0.90

0.93

0.87

0.87

0.87

Mean mesopore diameter (nm)

3.19

3.43

3.43

3.26

3.15

Phenol

0.026

0.425

0.050

0.608

0.361

Lactone

0.047

0.396

0.033

0.455

0.334

Carboxyl

0.051

0.913

0.062

0.660

0.985

Total acidity

0.124

1.834

0.145

1.723

1.680

Total basicity

0.475

0.002

0.305

0.005

0.188

Properties of catalysts 2

BET surface area (m /g) 2

Micropore area - DR method (m /g) 2

Mesopore area -BJH adsorption (m /g) Micropore volume - DR method (cm3/g) 3

Surface acidity (meq/g)

B BA C CA

Granular Calgon F-300 bituminous coal-derived activated carbon Catalyst B modified by sulfuric acid (96 wt%) Pellet 4GS coconut shell-derived activated carbon Catalyst C modified by sulfuric acid (96 wt%)

Catalyst BA impregnated with 10 wt% Fe (based on the mass of VR) BA-Fe *: data referred in reference 3.


27

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 28 of 33

Table 2. Experimental conditions and results for VR-SUP using various catalysts at 400 °C and a 3.45 MPa H2 partial pressure in supercritical solvents.

Catalyst

Reaction temperature (°C)

Reaction pressure (MPa)

Reaction time (min)

Liquid yield (wt%)

Total coke (wt%)

Conversion (wt%)

In supercritical m-xylene B*

399

8.32

30

66.3

16.0

83.3

BA

400

8.02

30

76.0

16.3

93.3

C

400

7.98

30

72.9

19.2

93.3

CA

400

8.22

30

64.2

30.3

96.4

BA-Fe

400

7.51

30

63.5

26.6

91.7

In supercritical n-dodecane B*

400

5.49

30

69.4

16.0

86.4

BA

400

5.98

30

84.4

8.4

93.3

C

401

6.08

30

71.5

20.6

93.4

CA

400

6.54

30

62.0

33.5

97.6

BA-Fe

400

5.26

30

69.6

22.3

93.3

*: data referred in reference 3.


28

Page 29 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Table 3. Experimental conditions and results for VR-SUP with catalyst BA for different temperatures, H2 partial pressures, reaction times, and additives in supercritical n-dodecane.

Process parameters Reaction temperature (°C)

Hydrogen pressure (MPa)


Experimental results

Reaction time (min)

Additive

Liquid yield (wt%)

Total coke (wt%)

Conversion (wt%)

Effect of reaction temperature 350 3.45 5.28 380 3.45 5.83 400 3.45 5.98

30 30 30

None None None

56.3 66.8 84.4

16.2 19.3 8.4

73.5 87.3 93.3

Effect of H2 partial pressure 400 0.50 3.28 400 1.38 3.76 400 3.45 5.98

30 30 30

None None None

87.2 82.7 84.4

12.1 12.4 8.4

100 95.9 93.3

Effect of reaction time 400 3.45 400 3.45 400 3.45

5.92 5.78 5.98

5 10 30

None None None

76.5 79.9 84.4

14.3 10.0 8.4

91.7 90.6 93.3

Effect of additives 400 3.45 400 3.45 400 3.45 400 3.45

5.98 6.57 6.21 6.19

30 30 30 30

None H2O MeOH EtOH

84.4 74.0 73.9 73.2

8.4 19.3 16.8 18.1

93.3 94.5 91.7 92.5


29

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 30 of 33

Table 4. Experimental conditions and results for VR-SUP with catalyst BA for different temperatures, H2 partial pressures, reaction times, and additives in supercritical m-xylene.

Process parameters Reaction temperature (°C)

Hydrogen pressure (MPa)


Experimental results

Reaction time (min)

Additive

Liquid yield (wt%)

Total coke (wt%)

Conversion (wt%)

Effect of reaction temperature 350 3.45 6.98 380 3.45 7.12 400 3.45 8.02

30 30 30

None None None

62.5 61.5 76.0

12.3 22.4 16.3

75.6 85.2 93.3

Effect of H2 partial pressure 400 0.50 5.62 400 1.38 6.08 400 3.45 8.02

30 30 30

None None None

67.2 77.1 76.0

30.9 13.7 16.3

100 91.6 93.3

Effect of reaction time 400 3.45 400 3.45 400 3.45

8.10 7.43 8.02

5 10 30

None None None

62.3 80.8 76.0

25.5 9.9 16.3

89.4 91.3 93.3

Effect of additives 400 3.45 400 3.45 400 3.45 400 3.45

8.02 8.79 8.38 7.58

30 30 30 30

None H2O MeOH EtOH

76.0 69.9 70.5 67.3

16.3 20.7 20.0 21.4

93.3 91.8 91.7 90.0


30

Page 31 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

AUTHOR INFORMATION Corresponding author Telephone: +82-2-2123-2762; Fax: +82-2-312-6401; E-mail: [email protected] (C.-H. Lee).

ACKNOWLEDGEMENTS This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) funded by the Korea Ministry of Trade, Industry & Energy (MOTIE) (20122010200050). The authors gratefully acknowledge the SIMDIS analysis from SK Innovation.

REFERENCES (1) Xu, C.; Hamilton, S.; Mallik, A.; Ghosh, M. Energy Fuels. 2007, 21, 3490-3498. (2) Nguyen-Huy, C.; Kweon, H.; Kim, H.; Kim, D. K.; Kim, D.-W.; Oh, S. H.; Shin, E. W. Appl. Catal., A. 2012, 447, 186-192. (3) Viet, T. T.; Lee, J.-H.; Ryu, J. W.; Ahn, I.-S.; Lee, C.-H. Fuel. 2012, 94, 556-562. (4) Mosio-Mosiewski, J.; Morawski, I. Appl. Catal., A. 2005, 283, 147-155. (5) Morawski, I.; Mosio-Mosiewski, J. Fuel Process. Technol. 2006, 87, 659-669. (6) Gray, M. R. Upgrading petroleum residues and heavy oils; CRC press, 1994; pp 37-40. (7) Sánchez, S.; Ancheyta, J. Energy Fuels. 2007, 21, 653-661. (8) Viet, T. T.; Lee, J. H.; Ma, F.; Kim, G. R.; Ahn, I. S.; Lee, C. H. Fuel. 2013, 103, 553-561. (9) Furimsky, E.; Massoth, F. E. Catal. Today. 1999, 52, 381-495. (10) Matsumura, A.; Kondo, T.; Sato, S.; Saito, I.; de Souza, W. F. Fuel. 2005, 84, 411-416.


31

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 32 of 33

(11) Looi, P. Y.; Mohamed, A. R.; Tye, C. T. Chem. Eng. J. 2012, 181–182, 717-724. (12) Leyva, C.; Rana, M. S.; Trejo, F.; Ancheyta, J. Catal. Today. 2009, 141, 168-175. (13) Leyva, C.; Rana, M. S.; Trejo, F.; Ancheyta, J. Ind. Eng. Chem. Res. 2007, 46, 7448-7466. (14) Ancheyta, J.; Rana, M. S.; Furimsky, E. Catal. Today. 2005, 109, 3-15. (15) Eom, H.-J.; Lee, D.-W.; Kim, S.; Chung, S.-H.; Hur, Y. G.; Lee, K.-Y. Fuel. 2014, 126, 263-270. (16) Dockner, T. Angew. Chem., Int. Ed. Engl. 1988, 27, 679-682. (17) Shimura, M.; Shiroto, Y.; Takeuchi, C. Ind. Eng. Chem. Fundam. 1986, 25, 330-337. (18) Fukuyama, H.; Terai, S. Pet. Sci. Technol. 2007, 25, 231-240. (19) Fukuyama, H.; Terai, S.; Uchida, M.; Cano, J. L.; Ancheyta, J. Catal. Today. 2004, 98, 207215. (20) Adams, J. J. Energy Fuels. 2014, 28, 2831-2856. (21) Aimoto, K.; Nakamura, I.; Fujimoto, K. Energy Fuels. 1991, 5, 739-744. (22) Farcasiu, M.; Smith, C. Energy Fuels. 1991, 5, 83-87. (23) Grunewald, G. C.; Drago, R. S. J. Am. Chem. Soc. 1991, 113, 1636-1639. (24) Son, S.-H.; Lee, J.-H.; Lee, C.-H. J. Supercrit. Fluids. 2008, 44, 370-378. (25) Lee, J.-W.; Lee, J.-H.; Viet, T. T.; Lee, J.-Y.; Kim, J.-S.; Lee, C.-H. Electrochim. Acta. 2010, 55, 3015-3021. (26) Jeon, P. R.; Choi, J.; Yun, T. S.; Lee, C.-H. Chem. Eng. J. 2014, 255, 705-715. (27) Park, J.; Son, S. Korean J. Chem. Eng. 2011, 28, 455-460. (28) He, J.; Shi, Y.; Ahn, S.; Kang, J. W.; Lee, C.-H. J. Phys. Chem. B. 2010, 114, 4854-4861. (29) Lee, S.; Seader, J.; Tsai, C. H.; Massoth, F. Ind. Eng. Chem. Res. 1991, 30, 607-613. (30) Baptist‐Nguyen, S.; Subramaniam, B. AIChE J. 1992, 38, 1027-1037.


32

Page 33 of 33

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

(31) Wiehe, I. A.; Liang, K. S. Fluid Phase Equilib. 1996, 117, 201-210. (32) Schabron, J. F.; Speight, J. G. Pet. Sci. Technol. 1998, 16, 361-375. (33) Al-Dahhan, M. H.; Larachi, F.; Dudukovic, M. P.; Laurent, A. Ind. Eng. Chem. Res. 1997, 36, 3292-3314. (34) Scott, D.; Radlein, D.; Piskorz, J.; Majerski, P.; debruijn, T. J. Fuel. 2001, 80, 1087-1099. (35) Castro, C.; Guerreiro, M.; Oliveira, L.; Gonçalves, M.; Anastacio, A.; Nazzarro, M. Appl. Catal., A. 2009, 367, 53-58. (36) Ke, J.; Han, B.; George, M. W.; Yan, H.; Poliakoff, M. J. Am. Chem. Soc. 2001, 123, 36613670. (37) Clark, P. D.; Kirk, M. J. Energy Fuels. 1994, 8, 380-387. (38) Du, H.; Fairbridge, C.; Yang, H.; Ring, Z. Appl. Catal., A. 2005, 294, 1-21. (39) Robell, A. J.; Ballou, E.; Boudart, M. J. Phys. Chem. 1964, 68, 2748-2753. (40) Savage, P. E.; Klein, M. T.; Kukes, S. G. Energy Fuels. 1988, 2, 619-628. (41) Arunajatesan, V.; Wilson, K. A.; Subramaniam, B. Ind. Eng. Chem. Res. 2003, 42, 26392643. (42) Choudhary, N.; Saraf, D. Ind. Eng. Chem. Prod. Res. Dev. 1975, 14, 74-83. (43) Matsushita, K.; Hauser, A.; Marafi, A.; Koide, R.; Stanislaus, A. Fuel. 2004, 83, 1031-1038. (44) Marafi, M.; Stanislaus, A. Appl. Catal., A. 1997, 159, 259-267. (45) Bae, Y. S.; Kim, M. B.; Lee, H. J.; Lee, C. H.; Ryu, J. W. AIChE J. 2006, 52, 510-521. (46) Cantero, D. A.; Bermejo, M. D.; Cocero, M. J. J. Supercrit. Fluids. 2013, 75, 48-57. (47) Koriakin, A.; Nguyen, H. V.; Kim, D. W.; Lee, C.-H. J. Supercrit. Fluids. 2014, 95, 175186.


33

Parametric Study for Upgrading Petroleum Vacuum Residue Using

Recommend Documents