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Quantum Chemistry Calculations on the Mechanism of Isoquinoline Ring-opening and Denitrogenation in Supercritical Water Fan He, Jianxiong Wang, Yonghong Li, and Hongwei SUN Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.7b00307 • Publication Date (Web): 24 Jan 2017 Downloaded from http://pubs.acs.org on February 2, 2017

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Industrial & Engineering Chemistry Research

Quantum Chemistry Calculations on the Mechanism of Isoquinoline Ring-opening and Denitrogenation in Supercritical Water Fan Hea,b, Jianxiong Wanga,b, Yonghong Li*,a,b and Hongwei Sunc a. Key Lab for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China b. National Engineering Research Center for Distillation Technology, Tianjin 300072, PR China c. Department of Chemistry, Nankai University, Tianjin 300071, PR China

Keywords: denitrogenation, ring-opening, supercritical water, density functional theory (DFT), heavy oil

Abstract

Computational studies at the M06/6-311G(d,p) and M06-2X/6-311+G(d,p) levels were performed to explore the detailed mechanism of isoquinoline ring-opening and denitrogenation in a supercritical water system. Three reaction paths with the same product, 2-(2-oxoethyl) 1 ACS Paragon Plus Environment


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benzaldehyde, were supported by the computational results. The rate-limiting step in the major degradation reaction is an addition reaction at the N position. H2O is added to both the 1C-2N double bond (1C-2N addition reaction) and the 2N-3C double bond (2N-3C addition reaction) of the isoquinoline molecule, where the oxygen of H2O is added to the carbon atom. The energy barrier of the 1C-2N addition reaction is 52.7 kcal/mol, while that of 2N-3C addition (from Path 6) is 60.1 kcal/mol. From catalysis by two water molecules, the barrier of 1C-2N addition (Reaction (1)) is reduced to 27.5 kcal/mol. Catalysis from water molecule clusters is shown to considerably affect the process of isoquinoline ring-opening and denitrogenation, as indicated by comparing the reaction energy barrier heights with and without water catalysts.

1. Introduction With the continuously growing demand for petroleum and decreasing reserve of regular crude oil, there has been much interests for the utilization1-4 and upconversion of heavy oil (≥ 100 cP)57

. Current upgrading technologies are based on carbon rejection and hydrogen addition routes,

which also contain limitations8. The carbon rejection route has a relatively low recovery of liquid, along with the generation of a large amount of coke, while in the latter route, the expensive catalysts tend to deactivate easily. Recently, supercritical water (SCW) upgrading technology has attracted much attention due to its outstanding solvent properties and green reaction processes9. Sato et al10. indicated that asphaltene could degrade in SCW, and the conversion rate increased as the temperature and water density increased. Morimoto et al.7 also obtained a number of lighter products and less coke by upgrading oil sand bitumen in SCW. They attributed the high conversion to the dispersion effect of SCW.

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SCW has also been reported to promote the removal of heteroatoms of heavy oil, including N, S, Ni, and V8, 11, 12. In this work, we focus on the denitrogenation process of heavy oil in SCW and choose isoquinoline as the research subject13, 14. Houser et al.15-17 demonstrated that almost 80% of isoquinoline is converted after reaction for 120 h at 450 °C and 32.27 MPa, and the main products are toluene, ethylbenzene and o-xylene. Houser15-17 also proposed an isoquinoline-SCW reaction scheme, as shown in Figure 1, indicating two ring-opening pathways. Ogunsola et al.18, 19

conducted experiments on quinoline and isoquinoline in SCW at 400 °C and 22 MPa for up to

48 h. They suggested that protons were donated by SCW to saturate the heterocyclic rings, and the reaction sequences were similar to those proposed by Houser and coworkers15-17.

Figure 1. Isoquinoline-water reaction scheme15. Nevertheless, many experimental studies have examined the isoquinoline degradation reaction15-19, but none of these studies gave detailed reaction equations and pathways. Isoquinoline is a complex and stable heterocyclic compound, and better insight into the ringopening and denitrogenation reactions are advantageous for further research into heterocyclic compounds. Furthermore, previous research has indicated that water molecules can reduce the energy barrier of gas-phase unimolecular reactions in several different systems20-22, however, the effects of SCW molecules in heavy oil systems and on the denitrogenation process are controversial. Investigating the specific effects of SCW on the denitrogenation process will elucidate the reason why isoquinoline can only reacts in SCW and cannot be pyrolyzed. 3 ACS Paragon Plus Environment


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Quantum chemistry calculations have been used to predict reaction mechanisms at the molecular level. Here, a quantum chemistry study was used to reveal the most reasonable and believable structures and reaction pathway on the potential energy surface (PES)12, 20, 23-26. This paper proposes six potential pathways and four steps for isoquinoline ring-opening and denitrogenation in the SCW system. Detailed reaction paths were established using the intrinsic reaction coordinate method, each stationary point energy on each reaction path was calculated, and finally the best paths were selected via comparison of the energies and configurations. In particular, the mechanism of N-C double bond rupture in the isoquinoline molecule was verified through an addition reaction with water molecules. Moreover, we demonstrate that water molecules can act as catalyst by forming water-catalyzed transition states, which can efficiently reduce the energy barrier in isoquinoline-SCW reactions. 2. Computational Method The Gaussian-09 suite27 of programs was used to carry out all quantum chemistry calculations presented here20. Calculation of the isoquinoline ring-opening and denitrogenation reactions were performed using the M06 and M06-2X functions28. Geometry optimization calculations of various reactants, products, and transition states (TSs) were conducted at the M06/6-311G(d,p) level. The TSs for all reactions were located using the Berny/QST2/QST3 routine. Then, normalmode frequency analysis was performed for all optimized geometries to verify that all the stable minima had positive frequencies and that the TS geometries had only one imaginary frequency. Intrinsic reaction coordinate (IRC) calculations were performed at the M06/6-311G(d,p) level to unambiguously verify the location of the transition state connecting the reactant and the product20, 21. M06-2X/6-311+G(d,p) was used to obtain the single point energy on the optimized geometries, and normal-mode frequency analysis was also used to estimate the zero-point


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vibrational energy corrections20,

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associated with the barrier heights29. The basis set

superposition error (BSSE) which has a negligible effect, can be ignored in calculations of chemical reaction energy barrier heights. Furthermore, in the discussion of catalysis in the isoquinoline + nH2O reaction, the hydrogen bonding energy was considered because the water molecules catalyzed as short chains in the system. All structures were further optimized using at the M06-2X/6-311+G(d,p) level. Normalmode frequency analysis and IRC were performed at the same level. B2PLYP-D3(BJ)/ma-tzvp3032

with basis set superposition error (BSSE) correction was used to accurately calculate the single

point energy that included hydrogen bonding, and the single point energy was corrected by the zero-point energy scale factor33 (0.970). 3. Results and Discussion 3.1 Potential Pathways for Isoquinoline Ring-opening and Denitrogenation Reactions in SCW

Figure 2. Atom labels in the isoquinoline structure. Figure 2 shows the labeling of atoms in the isoquinoline molecule, and the following discussion is based on these atom labels. Previous research from Houser et al.15-17 and Ogunsola et al.18,

19

demonstrated that the isoquinoline degradation reaction should only occur at the 5 ACS Paragon Plus Environment


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nitrogen-containing aromatic ring due to the existence of the benzene series products. Based on previous research15-17, the C-N bond of isoquinoline is attacked by the short chain water clusters34, 35. As shown in Figure 1, the ring-opening reaction can occur at both the 1C-2N position and 2N-3C position and produce two different, but both important, chemicals in parallel. Bond rupture at either the 1C-2N or 2N-3C position requires at least two steps, the first of which is the rupture of the extended π bond via an addition mechanism, followed by the cleavage of the C-N σ bond at the corresponding position. In the first step, the oxygen atom of the hydroxyl is added to the 1C or 3C position, while the hydrogen atom of a water molecule is added to the nitrogen atom of isoquinoline. Although in this step water molecules can break the extended π bond along 3C-4C, this addition reaction is neglected in this article due to its high energy barrier (66.5 kcal/mol). The denitrogenation process after ring-opening also requires at least two steps, which are saturation of the remaining π bond on the unreacted C position and denitrogenation through elimination. To summarize, the entire isoquinoline ring-opening and denitrogenation reaction process contains four steps: (1) N-position addition reaction, (2) ring-opening reaction, (3) Cposition addition reaction, and (4) denitrogenation reaction. Different combinations of these four steps results in six potential pathways for the isoquinoline ring-opening and denitrogenation reactions, as shown in Figure 3. Each single reaction numbered in Figure 3 will be discussed below.


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Figure 3. Reaction paths diagram. Based on the attack position in Step 1, these six pathways are divided into two categories: the 1C-2N reaction sequence (Path 1, Path 2, and Path 3) and the 2N-3C reaction sequence (Path 4, Path 5, and Path 6). Figure 4 shows the detailed reaction equations of the 1C-2N reaction sequence. Step 1 of these three pathways is identical: a water molecule attacks the extended π bond along 1C-2N (Reaction (1)). After that, there are two possibilities for Step 2. For Path 1, a ring-opening reaction at the 1C-2N position (Reaction (2)) occurs through intramolecular proton transfer from the hydroxyl group at the 1C position to the 2N position. In contrast to Path 1, a C-C addition reaction occurs first for Path 2 and Path 3. The heterocyclic ring saturated with a water molecule attacks the remaining p orbital electrons at the 3C-4C position (Reaction (5)). In Step 3, the 3C-4C π bond is saturated in Path 1 (Reaction (3)), while in Path 2 and Path 3, σ bond cleavage occurs at 1C-2N



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(Reaction (6)) and 2N-3C (Reaction (7)), respectively. Finally, the deamination reaction occurs in all three paths, producing the same final product of 2-(2-oxoethyl) benzaldehyde.

Figure 4. Reaction equations for Path 1, Path 2 and Path 3. Figure 5 shows the detailed reaction equations of the 2N-3C reaction sequence. The reaction equations in these three paths are similar to those discussed above for the 1C-2N reaction sequence, apart from the different position of N-C addition. For these three paths, the hydroxyl group is located at the original 3C position instead of the 1C position, after Step 1 (Reaction (8)). In Step 2 of Path 4, the ring-opening reaction occurs at the 2N-3C position (Reaction (9)). Then, in Step 3, the remaining π bond at the 1C-4C position is saturated (Reaction (10)), and finally, deamination occurs on the original 1C position (Reaction (11)) in Step 4. Step 2 of Path 5 and Path 6 is similar with Path 3 and Path 4; the whole nitrogen-containing aromatic ring is saturated before ring-opening (Reaction (12)). After Step 2, the ring ruptures at the 2N-3C position and 1C-2N position in Path 5 (Reaction (7)) and Path 6 (Reaction (6)), respectively. Finally, in Step 4, denitrogenation occurs at the original 1C position (Reaction (11)) in Path 5, while in Path 6, it occurs at the original 3C position (Reaction (4)). 8 ACS Paragon Plus Environment

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Figure 5. Reaction equations for Path 4, Path 5 and Path 6. Remarkably, these six pathways produce the same final product, 2-(2-oxoethyl) benzaldehyde. This aldehyde compound can be rapidly converted into ethyl benzene and o-xylene16, 17. Ethyl benzene and o-xylene were found to be the major products in experimental studies15, which is consistent with our simulation results. 3.2 Energy Barrier Comparison between Different Steps Energy barrier data of each step in the six different pathways are compared in order to discuss and elucidate the most likely pathway in the isoquinoline ring-opening and denitrogenation reaction. Figures 6-10 show the energy barrier comparison of the four steps. 3.2.1 Energy Barrier Analysis of Step 1: C-N Addition Reaction Figure 6 shows the zero-point energy (ZPE) of the reactants (R), reactant-complexes (RC), transition states (TS), and products (P) in the 1C-2N addition reaction (Reaction (1)) and 2N-3C addition reaction (Reaction (8)). The ZPE of R and P is the sum of the energies of all the molecules in the reactants and products, including the energy of the water molecule. In the



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following figures, the ZPE of R and P is defined as above. The potential energy profile in Figure 6 shows that the 1C-2N addition reaction has a lower energy barrier (TS-RC), suggesting that it might be the dominant reaction pathway. However, the energy barrier difference between 1C-2N addition and 2N-3C addition is only 7.4 kcal/mol, and the experimental work of Houser et al.15, 16 demonstrated that both reactions can occur based on the analysis of the resultant products. Thus, we suggest that addition reactions at both the 1C-2N position and 2C-3N position are involved in isoquinoline degradation in SCW.

Figure 6. Potential energy profiles for the reactions in Step 1: the 2N-3C addition reaction (Reaction (8), red) and the 1C-2N addition reaction (Reaction (1), black). 3.2.2 Energy Barrier Analysis of Step 2: Aromatic Ring-opening Reaction and C-C Addition Reaction Figure 7 gives the potential energy profile of the six pathways in Step 2. The energy barriers of the two reactions in the 1C-2N reaction sequence are very close (Reaction (2), 44.3 kcal/mol; Reaction (5), 47.0 kcal/mol), as shown in the lower part of Figure 7. Thus, both paths may occur simultaneously in Step 2. The upper part of Figure 7 shows that the 1C-4C addition reaction


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(Reaction (12), 33.8 kcal/mol) has a large energy advantage over the 2N-3C ring-opening reaction (Reaction (9), 52.0 kcal/mol). The energy barrier of the former reaction is almost 18.2 kcal/mol lower than that of the latter. Therefore, the 1C-4C addition reaction, in other words, the saturation of the nitrogen-containing aromatic ring, may be the main channel for the 2N-3C reaction sequence in this step. Moreover, the energy barrier of this dominant reaction is also lower than that of the two paths in the 1C-2N reaction sequence. Reaction (12) has an energy advantage of 10.5 kcal/mol over Reaction (2). Although the 2N-3C reaction sequence has a 7.4 kcal/mol disadvantage in Step 1, the 10.5 kcal/mol advantage at this step further supports our claim in the above analysis that both reaction sequences can occur in this system.

Figure 7. Potential energy profiles for the reactions in Step 2. Top: the 2N-3C ring-opening reaction (Reaction (9), red) and the 1C-4C addition reaction (Reaction (12), purple); Bottom: the 1C-2N ring-opening reaction (Reaction (2), blue) and the 3C-4C addition reaction (Reaction (5), black). 3.2.3 Energy Barrier Analysis of Step 3: C-C Addition Reaction and Saturated RingOpening Reaction



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Figure 8a and 8b shows the ZPE and energy barrier of the 2N-3C reaction sequence and 1C-2N reaction sequence in Step 3, respectively. As shown in Figure 8a, the 1C-4C addition reaction, after the 2N-3C ring-opening reaction, (Reaction (10)) has the smallest energy barrier among the three paths of the 2N-3C reaction sequence. However, this reaction follows the 1C-4C addition reaction (Reaction (12)), which was ruled out in Step 2 due to its large energy disadvantage. Thus, the main channel for the 2N-3C reaction sequence in Step 3 should be the 1C-2N ringopening reaction (Reaction (6), 37.2 kcal/mol), which has the second lowest energy barrier. This also shows that the saturated nitrogen-bearing ring ruptures more easily at the 1C-2N position than at the 2N-3C position. For the 1C-2N reaction sequence, shown in Figure 8b, the 1C-2N ring-opening reaction (Reaction (6), 37.2 kcal/mol) has the lowest energy barrier. Since this sequence can undergo two possible reactions in Step 2, the product of the 1C-2N ring-opening reaction (Reaction (2)) should also be attacked in Step 3. The attack position should be the remaining 3C-4C π bond. Therefore, the 1C-2N position sequence has two main channels in Step 3. One is the 3C-4C addition reaction (Reaction (3), 54.0 kcal/mol) after the 1C-2N ring-opening reaction, even though its energy barrier is the highest in Step 3. The other is the 1C-2N ringopening reaction on the saturated nitrogen-containing ring (Reaction (6)).


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Figure 8. Potential energy profiles for the reactions in Step 3. Left (a): the 2N-3C reaction sequence including the 2N-3C ring-opening reaction (Reaction (7), purple), the 1C-2N ringopening reaction (Reaction (6), blue), and the 1C-4C addition reaction (Reaction (10), red); Right (b): the 1C-2N reaction sequence including the 2N-3C ring-opening reaction (Reaction (7), purple, same as in (a)), the 1C-2N ring-opening reaction (Reaction (6), blue same as in (a)), and the 3C-4C addition reaction (Reaction (3), black) 3.2.4 Energy Barrier Analysis of Step 4: Denitrogenation Reaction Figure 9 shows the ZPE of the reactants (R), transition states (TS), product-complexes (PC), and products (P) in the denitrogenation reactions in both the 1C-2N reaction sequence and the 2N-3C reaction sequence. Only two denitrogenation reactions occur in the system: nitrogen atom elimination at the original 3C position (Reaction (4)) or the original 1C position (Reaction (11)). Both reaction sequences include these two denitrogenation reactions. The energy barrier difference between the 3C denitrogenation reaction (Reaction (3), 35.2 kcal/mol) and the 1C denitrogenation reaction (Reaction (11), 35.8 kcal/mol) is only 0.6 kcal/mol, indicating a similar reaction probability for the two denitrogenation reactions.



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Figure 9. Potential energy profiles for the reactions in Step 4: the 3C denitrogenation reaction (Reaction (4), black) and the 1C denitrogenation section (Reaction (11), red) From the above energy barrier analysis, it can be concluded that there are three possible pathways for the isoquinoline ring-opening and denitrogenation process. As shown in Figure 10, Path 1 and Path 2 are the possible pathways for the 1C-2N reaction sequence, while Path 6 is the possible pathway for the 2N-3C reaction sequence.

Figure 10. Potential energy profiles for three possible pathways: Path 1 (black), Path 2 (blue) and Path 6 (red) 3.3 Catalysis Mechanism of Water Molecule in SCW 3.3.1 Catalytic TS Structures in the 1C-2N Addition Reaction


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Figure 11. Geometries of the 1C-2N addition reaction and water-catalyzed TS structures. Since many steps in the isoquinoline degradation reaction involve an H-transfer mechanism, investigating the catalysis mechanism of water in the isoquinoline degradation reaction system is of importance. In the following discussion, transition states having different numbers of water molecules in the isoquinoline ring-opening process are investigated. Figure 11a shows the optimized geometries of the isoquinoline reactant, transition state (TS1), and addition product in the non-catalyzed 1C-2N addition reaction. Figure 11b shows the structure of TS1 with only one water molecule acting as the reactant. In the TS1, the hydrogen atom of the water molecule attacks the nitrogen atom first, then the oxygen atom attacks the carbon atom, forming a four-membered ring, in which the H-O-H angle is significantly bent from 104.0° to 156.6°. In addition, the dihedral angle between the N-H bond and 3C-4C bond (153.7°) is different from that in the equilibrium structure of the 1C-2N addition product (177.2°). Thus, when the product is formed via the direct water molecule addition reaction, reorientation of the



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water molecule and the N-position bond is required, which is the cause of the high energy barrier of the 1C-2N addition reaction. Figure 11c shows the transition state structure (TS2) in the 1C-2N addition reaction. Compared with TS1, TS2 has an extra water molecule acting as a catalyst. The two water molecules, together with the 1C-2N bond of isoquinoline form a six-membered ring. In this configuration, the H-O-H angle of the water molecule is 134.9°, smaller than that of the TS1 structure (Figure 11b). Additionally, the dihedral angle between the N-H bond and 3C-4C bond (160.6°) is also closer to the equilibrium structure. It can be inferred that the six-membered ring is more stable than the four-membered ring due to its smaller steric hindrance. Figure 11d shows the transition state structure (TS3) in the 1C-2N addition reaction with two water molecules acting as catalysts. In a similar manner, an eight-membered ring in formed with the three water molecules and the 1C-2N bond of isoquinoline. Compared with the previous data, the H-O-H angle in TS3 is bent only slightly (125.7°), and the dihedral angle (179.3°) is almost the same as that of the addition product (177.2°). Figure 11e shows the transition state structure (TS4) in the 1C-2N addition reaction with three water molecules acting as catalysts. The ten-membered ring in TS4 consists of four water molecules and the 1C-2N bond of isoquinoline. The H-O-H angle in TS4 has the closest value (97.3°) to that of the equilibrium structure among the four transition states. However, the dihedral angle (159.2°) is far from the equilibrium value (177.2°). Thus, TS4 is not a stable structure. These results indicate that TS3 has the most similar structure to the equilibrium structure of the 1C-2N addition reaction product. In this structure, very little reorientation of the water molecule (20.9%) and isoquinoline molecule (1.2%) is required for reaction. In other words, the eight-


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membered ring can greatly reduce the steric hindrance compared with the other three transition state structures. 3.3.2 Catalytic Energy Barriers of 1C-2N Addition Reaction

Figure 12. Potential energy profiles for the 1C-2N addition reaction (Reaction (1)): no catalyst (black), one water molecule catalyst (red), two water molecule catalysts (purple) and three water molecule catalysts (blue). Next, the energy barriers of the 1C-2N addition reaction with different numbers of water molecules as catalysts (n=0, 1, 2, 3) are compared at the B2PLYP-D3(BJ)/ma-tzvp level30-32 in order to determine the optimal catalytic structure (Figure 12). The energy barrier of the 1C-2N addition reaction without catalyst is 47.5 kcal/mol, which is 18.7 kcal/mol higher than the energy of the 1C-2N addition reaction with one water molecule catalyst. This means that a water molecule can effectively reduce the reaction barrier in the extended π bond opening reaction. As Figure 12 shows, the 1C-2N addition reaction with two water molecules as catalysts has the lowest energy barrier (20.4 kcal/mol), and thus TS-3 is the optimal catalytic structure. The energy barrier of the 1C-2N addition reaction with three water molecules catalyst is 1.6 kcal/mol



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higher than that of the TS3 structure. A possible reason for this is that ten-membered ring is not favorable. 3.3.3 Comparison of Non-catalyzed and One Water Molecule Catalyzed Reactions Moreover, among the six pathways for isoquinoline ring-opening and denitrogenation, almost all reactions involve the H-transfer mechanism, and thus it is also important to investigate the catalysis effect of water in these reactions. Figure 13 shows the energy barrier of all twelve reactions in the isoquinoline-SCW reaction in the absence and presence of water catalyst. The results indicate that with the presence of one water molecule as a catalyst, the energy barrier of these reactions decreased substantially, especially for the 1C-2N addition reaction (Reaction (1), ∆=20.4 kcal/mol) and 2N-3C addition reaction (Reaction (8), ∆=19.7 kcal/mol). Since the C-N addition reaction has the highest energy barrier of all the reactions, the significant barrier reduction of this reaction explains why isoquinoline can be degraded in SCW, which provides abundant short chain water clusters to catalyze the isoquinoline degradation reaction.


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Figure 13. Energy barrier comparison between the reactions without catalyst (black) and with one water molecule as a catalyst (red). The reaction numbers are defined as in Figure 3. 4. Conclusion The ring-opening and denitrogenation processes in the isoquinoline degradation reaction in SCW are currently believed to occur synchronously through three pathways: Path 1, Path 2 and Path 6. Quantum chemistry calculations showed that the ring-opening reaction (Path 1, Step 2) and saturation reaction (Path 2, Step 2) can occur simultaneously in the 1C-2N reaction sequence. The rate-determining step of Path 1 is Step 3, the 3C-4C addition reaction (Reaction (3); energy barrier, 54.0 kcal/mol), and for Path 2, it is Step 1, the 1C-2N addition reaction (Reaction (1); energy barrier, 52.7 kcal/mol). In the 2N-3C reaction sequence, Path 6 is the only possible pathway. The rate-determining step of Path 6 is Step 1, the 2N-3C addition reaction (Reaction (8); energy barrier, 54.0 kcal/mol). According to the rate-determining steps of above three main paths, Path 2 has the lowest energy barrier; thus, it should be the best pathway for the isoquinoline ring-opening and denitrogenation process. Furthermore, in the isoquinoline + 3H2O reaction, the energy barrier of the 1C-2N addition reaction is reduced from 52.7 kcal/mol to 27.5 kcal/mol, indicating the short chain water clusters from SCW work as catalysts during the degradation of isoquinoline. A simple comparison of the energy barriers of all of the paths shows that water molecules can catalyze each reaction in each pathway and considerably reduce all of the energy barriers. Acknowledgments We gratefully acknowledge the financial support from China’s National Petroleum Corporation (project PRIKY15007).



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Supporting Information More details on the geometries of species (including reactants, products, and transition states) and experimental results of Houser et al.15-17 and Ogunsola et al.18,

19

(which validate our

calculations). This material is available free of charge via the Internet at http://pubs.acs.org. Corresponding Author *Tel.: +86 22 27404701-8858. Fax: +86 022 27404705. E-mail: [email protected]. References 1.

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CHALLENGE OF THE PETROLEUM REFINING INDUSTRY. Petroleum & Coal 2011, 53, (1), 27-44. 3.

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Review of SAGD-ISSLW. Petroleum Science & Technology 2014, 32, (6), 753-760. 4.

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