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Article

Efficient Synthesis of Nickel-Molybdenum/USY-Zeolite Catalyst for Eliminating Impurities (N, S, and Cl) in the Waste Plastic Pyrolysis Oil: Dispersion Effect of Active Sites by Surfactant-Assisted Melt-Infiltration

by
Eui Hyun Cho
1,†,
Ki-Duk Kim
2,†,
Byung Sun Yoon
1,†,
Eunkyung Cho
1,
Yeon Jeong Yu
1,
Tuan Ngoc Phan
3,
Sang-Goo Jeon
2 and
Chang Hyun Ko
1,*
1
School of Chemical Engineering, Chonnam National University, Gwangju 61186, Republic of Korea
2
Climate Change Research Division, Korea Institute of Energy Research, Daejeon 31136, Republic of Korea
3
Faculty of Chemistry, VNU University of Science, Vietnam National University, Hanoi 100000, Vietnam
*
Author to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Catalysts 2023, 13(12), 1476; https://doi.org/10.3390/catal13121476
Submission received: 2 November 2023 / Revised: 20 November 2023 / Accepted: 25 November 2023 / Published: 28 November 2023
(This article belongs to the Special Issue State-of-the-Art of Catalytical Technology in Korea)
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Abstract

:
The upgrading of waste plastic pyrolysis oil (WPPO) through hydrotreating (HDT) is crucial for transforming plastic waste into chemical feedstock. The catalytic role of HDT is of paramount importance for this conversion procedure. In this study, bimetallic catalysts based on Ni and Mo were prepared using the surfactant-assisted melt-infiltration (SAMI) method, completely omitting the use of liquid solutions. Thorough analysis via X-ray diffraction, transmission electron microscopy, and hydrogen temperature-programmed reduction confirmed that the addition of Span60 surfactant effectively prevented the aggregation of Ni and Mo components, reduced the size of metal particles, and improved the dispersion of active sites on the zeolite supports. Consequently, NiMo-based catalysts incorporating Span60, synthesized using the SAMI method, exhibited a superior catalytic performance in the removal of nitrogen, sulfur, and chloride impurities from WPPO during HDT compared to those without surfactant. Specifically, the catalyst prepared with Span60 exhibited 15% higher nitrogen conversion compared to the catalyst prepared without Span60.

Graphical Abstract

1. Introduction

Plastic products are indispensable in daily life. However, plastic waste causes serious environmental pollution, and it should be covered as eco-friendly by using a recycling system [1]. Although a huge amount of plastic waste is recycled, there are limits to recycling plastic waste because recycled plastic wastes can only be used to produce low-quality products. Therefore, most plastic wastes have been incinerated and landfilled, causing severe environmental pollution and exposing humans to harmful pollutants [2,3]. Recent studies have demonstrated that the incomplete incineration of plastic often leads to the release of numerous toxins, including volatile organic compounds, polybrominated dibenzo-p-dioxins and furans, heavy metals, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and various other gaseous emissions into the environment [4]. These toxins have direct and severe health consequences, which include an increased risk of cancer and respiratory diseases, neurological disorders, damage to the immune and nervous systems, and cardiovascular diseases [5]. The research on plastic waste recycling as a resource has been actively carried out worldwide. In particular, the development of the thermochemical recycling process was actively conducted to make high-value fuels in refinery companies [6]. The plastic products are manufactured from naphtha produced by the distillation of crude oil. In other words, naphtha can be produced from the decomposition of plastic wastes [7,8]. However, impurities such as nitrogen, chloride, and sulfur in the wasted plastic pyrolysis oil (WPPO) derived from thermally treated plastic waste should be eliminated to produce high-quality naphtha using the hydrotreating (HDT) process [9,10].
The HDT process has a long history of about 60 years in a crude oil distillation process unit and has a key role as one of the largest processes in refining processes [11]. The WPPO recycling system was combined with non-catalytic thermal decomposition and hydro-purifying catalytic processes composed of HDT and hydrocracking (HCK) [12]. The non-catalytic thermal decomposition process produces WPPO with aromatic, alkane, and alkene with high carbon numbers. In addition, WPPO includes many impurities such as nitrogen, chlorine, and sulfur, since the various chemicals were added to the complete plastic products and the feedstock of WPPO process for the formation of functional groups and an overcoat on the surface of the plastic products [13]. Thus, the plastic waste contains nitrogen, chloride, and sulfur impurities that can poison the catalyst bed inside the HCK process. To avoid catalytic poisoning of the HCK process, the complex HDT process including hydrodechlorinization (HDCl), hydrodesulfurization (HDS), and hydrodenitrogenation (HDN) should appropriately eliminate the impurities using efficient HDT catalysts [14,15].
Parameters of the HDT process, such as temperature, pressure, liquid hour space velocity, type of reactor as batch and/or fixed bed, and catalyst types should be efficiently designed to achieve a high performance of the HDT reaction [16]. In particular, catalysts, which are the high dispersion of active sites and the optimization of acid site loading on the surface of the support, should be properly characterized according to the reaction environment [17]. Thus, nickel [18] and molybdate [19] supported on ultra-stable Y zeolite (Ni-Mo/USY zeolite) catalysts have been widely used in HDT reactions [20,21,22,23]. Dien Li et al. studied NiMo catalysts that were synthesized using various zeolite types such as NaY, USY, H-mordenite, and ZSM-5. The NiMo/USY catalyst showed the best catalytic performance in HDS and HCK because appropriate acid sites were optimized, and NiMo particles have homogeneously existed at the mesopore structure of USY zeolite [24]. They also investigated the NiMo/γ-Al2O3-USY catalyst having a higher reaction performance in HDS and HCK than the NiMo/γ-Al2O3 catalyst because Ni and Mo particles were uniformly distributed and easily sulfidated on the surface of γ-Al2O3-USY support. Furthermore, the USY zeolite addition has enhanced the acidity on the surface rather than the surface of fresh-Al2O3 support [25]. W. Huang et al.’s group prepared NiMo supported on the Ni-modified Y zeolite catalyst using the in-situ synthesis method for the HDS reaction. The NiMo/Ni-modified Y zeolite catalyst shows uniform particle dispersion and an increase in a number of active sites in Y zeolite that enhance sulfide molecular adsorption [26]. W. Zhou et al. reported that NiMo supported on USY zeolite catalysts was synthesized for the 4,6-dimethyldibenzothiophene (4,6-DMDBT) HDS reaction. USY zeolites were modified using the in-situ synthesis, the ion exchange, and the impregnation method, resulting in Ni-modified USY zeolite. According to the synthesis method, differences in NiMo dispersion were observed, and the degree of NiMo sulfidation was a key factor in the 4,6-DMDBT HDS reaction [27]. Applying an appropriate catalyst synthesis that can highly disperse the NiMo particles and increase the capable sulfidation is a major issue in the HDT catalyst design.
The melt-infiltration (MI) method is a straightforward and solid-state method for the synthesis of a heterogeneous bimetallic catalyst and can produce a catalyst satisfying a high dispersion of the metallic active site [28]. Since this method does not require a solvent for impregnating metal precursors into the support, liquid waste is not generated in the catalyst synthesis procedure [29]. We studied that alkali metals (Ca, Mg, Sr, and Ba) were doped on the nickel-based/Al2O3 catalyst using the MI method. The low loading (5 wt.%) of the calcium nitrate precursor can facilitate the infiltration with the nickel precursor into Al2O3 support. The nickel and calcium particles were well-distributed on the support and showed an efficient catalytic performance in the CO2 methanation reaction [30]. Furthermore, our group recently developed MI to surfactant-assisted melt-infiltration (SAMI) using a solid-state surfactant. The nickel particles were highly dispersed on the support at nano-size (~11 nm) due to the addition of non-ionic surfactant Span60, and showed the best performance in the CO2 methanation reaction [31]. The application of Span60 surfactant is not only for the CO2 methanation reaction, but also for the water gas shift reaction and ammonia decomposition reaction [32,33]. In these reactions, we proved that the high dispersion of active sites via the addition of Span60 surfactant plays a critical role for the enhancement of catalytic activity.
In this study, we prepared the Ni monometallic catalyst and the Ni-Mo bimetallic catalyst supported on USY zeolite using the SAMI and MI methods. The Span60 surfactant was added to obtain a high dispersion of nickel and molybdenum particles in the USY pore structure. The catalysts were prepared using the Y zeolite, named CBV720 and WSY-60H, and the characteristics of these supports were compared in the HDT reaction condition. The catalysts with Span60 surfactant exhibited a high dispersion of NiMo particles and an excellent ability to eliminate impurities in the HDT reaction.

2. Results and Discussion

2.1. Catalytic Activity Test

Figure 1 presents the conversion of S, N, and Cl impurities in the WPPO over Ni-Mo sulfide catalysts, as analyzed through analysis with an X-ray fluorescence (XRF) instrument and a total nitrogen and sulfur (TNS) analyzer. The sulfidation process of the NiMo-Com, NiMo/CBV-720, S60/NiMo/CBV-720, NiMo/WSY-60H, and S60/NiMo/WSY-60H catalysts was carried out with dimethyl disulfide at 400 °C. The S and N conversions of all Ni-Mo catalysts were over 90 wt.% and 70 wt.%, respectively, indicating the high activity of Ni-Mo catalysts for the desulfurization and denitrogenation. In addition, the Cl ions were absent in the HDT product, demonstrating that Cl is totally eliminated from the WPPO. Therefore, it is confirmed that the S, N, and Cl impurities in the WPPO can be well reduced over the NiMo-based catalysts. The N conversion followed the order S60/NiMo/WSY-60H > S60/NiMo/CBV-720 > NiMo-Com > NiMo/WSY-60H > NiMo/CBV-720. Similarly, the S conversion followed the order S60/NiMo/WSY-60H > S60/NiMo/CBV-720 > NiMo/CBV-720 > NiMo/WSY-60H > NiMo-Com. These results indicated that the Span60 surfactant plays a critical role in the catalytic activity of the bimetallic NiMo-based catalysts. The catalysts with the presence of Span60 exhibited higher desulfur and denitrogen conversion than the catalysts without Span60 did. The Span60 surfactant significantly affects the dispersion and the size of the active sites on the surface of the catalysts. The influence of the surfactant on the catalytic performance of the NiMo-based catalysts are proved by an X-ray diffraction (XRD) with Joint Committee on Powder Diffraction Standards (JCPDS), N2-sorption measurement with Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH) methods, high-resolution transmission electron microscopy (HR-TEM), high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), and hydrogen temperature-programmed-reduction (H2-TPR).

2.2. Structure of the Ni-Mo Catalysts

Figure 2 showed the XRD patterns of the CBV-720 and WSY-60H (supports and the corresponding reduced catalysts). Before the XRD analysis, the reduction of prepared catalysts was performed at 400 °C in an H2 environment for 2 h. The diffraction peaks of zeolite supports are maintained after the introduction of metal species (Ni and Mo) and Span60 surfactant. All reduced catalysts show the peaks corresponding to MoO2 (PDF #65-1273) and metallic Ni (PDF #04-0850) at about 26° and 44.5°, meaning that the reduction process converts MoO3 and NiO to MoO2 and metallic Ni, respectively. MoO3 was reduced to MoO2, not metallic Mo, because of the low reduction in temperature. In the NiMo/CBV-720, the MoO2 peak at 26° and the Ni peak at 44.5° might be overlapped with the neighbor CBV-720 peaks, forming the broadened peaks. However, in the S60/NiMo/CBV-720 catalyst, these peaks correspond to pristine CBV-720 support. It might come from the smaller particle size and the high dispersion of active materials on the support with the presence of Span60 surfactant. The catalysts with the WSY-60H support show a similar tendency in the XRD patterns. Mo and Ni are successfully introduced to the zeolite supports. The addition of Span60 surfactant might enhance the dispersion of metal species on the support and decrease of particle size, which significantly affect the HDT performance of the catalysts.
Figure 3 shows the N2 adsorption–desorption isotherms and the pore size distributions of NiMo catalysts on the CBV-720 and WSY-60H supports after reduction, respectively. Table 1 indicates the physical properties of the zeolite supports and NiMo-based catalysts, including BET surface area, total pore volume, and dominant pore diameter. These isotherms are in accordance with Ⅳ type and the H4 hysteresis loop classified by IUPAC, indicating the mesoporous structure with narrow slip pores of the supports and the catalysts. Although CBV-720 and WSY-60H are kinds of zeolites characterized by micropores, they exhibited a broad distribution of mesopores, as both zeolites are USY zeolites that form via the dealumination of Y-type zeolite. Figure 3a,c exhibited that the impregnation of Mo particles and the addition of Span60 to the catalysts reduced the total N2 adsorption and dragged the isotherms down. These indicated that the active materials were efficiently dispersed in the pores of the zeolite supports and occupied the empty spaces inside the pores, leading to the decrease of the BET-specific surface area and total pore volume. It is further proved by the pore size distribution in Figure 3b,d. Figure 3b,d indicated that both the supports showed the dominant pore diameter of 2.4 nm. The pore size distributions of the catalysts are unaffected by the impregnation of metal particles and Span60. However, after the impregnation of Mo particles, Span60 decreased the number of mesopores. It was estimated that the added Span60 induced the Ni and Mo particles to penetrate into the mesopores and prevented them from moving to the outside. Thus, the total N2 adsorption, specific surface area, and dominant pore size were decreased. According to the aforementioned effect, Ni and Mo particles were highly dispersed into the mesopores of the supports in the presence of Span60, leading to the better performance of those catalysts with Span60 added.

2.3. Highly Dispersed Ni and Mo Particles on a Zeolite Support

Figure 4 shows the TEM and element mapping images of NiMo catalysts on both CBV-720 and WSY-60H supports. Figure 4a,d display the TEM image and the Ni particle distribution of the Ni-based catalyst supported on CBV-720 and WSY-60H, respectively. The Ni particles were extremely agglomerated with themselves and form the larger particles outside the support. The size of Ni particles was about 50 nm. It can be realized that similar behavior appeared in the NiMo bimetallic catalysts in Figure 4b,e. The Ni particles were highly aggregated outside the supports as the preparation of MI is inappropriate for the high dispersion of nickel particles at a given (~5 wt.%) nickel loading, whereas the Mo particles were well dispersed on the CBV-720 and WSY-60H supports. Figure 4c,f display the TEM and element mapping images of the NiMo-based catalysts with the addition of Span60 surfactant. The Mo particles were well distributed on the supports regardless of the presence or absence of Span60. On the other hand, it is noteworthy that the Ni particle dispersion was greatly enhanced by the addition of Span60. The Ni particles distributed uniformly on the surface of the supports with the presence of Span60. This leads to a smaller Ni particle size compared to those in the catalyst without Span60. Span60 addition seemed to facilitate the dispersion of Ni particles in the pores in CBV-720 and WSY-60H supports. The penetration of the Ni particle into the pores was verified by the aforementioned N2 adsorption–desorption result. In the sulfidation process of NiMo-based catalysts, it is established that MoO3 particles undergo a transformation, resulting in the creation of a slab-shaped MoS2 where Ni particles are situated and serve as active sites [34]. Jennifer Hein et al. emphasized the crucial role of the proximity of Ni-Mo oxide particles in improving the catalytic activity of NiMo sulfide catalysts for both HDN and HDS reactions [35]. Through extended X-ray absorption fine structure spectroscopy, they observed that, in Ni-Mo catalysts, Ni, which does not integrate into the Ni-promoted phases, segregates and forms bulk Ni sulfide species. This means that the NiMo catalysts prepared with Span60 confirmed the high dispersion of Ni and Mo particles in Figure 4c,f, and exhibit enhanced catalytic activity for the HDT reaction. Therefore, the high dispersion effect played a very important role in the activity of the NiMo-based catalysts.
H2-TPR analysis was performed to confirm the reducibility of the synthesized catalysts related to the HDT activity. The results of H2-TPR analysis are shown in Figure 5. It can be seen that the catalysts with two types of zeolite supports exhibit the similar H2-TPR profile, indicating the same reducibility of metal species on the supports. In the Ni-based catalysts, all the reduction peaks occur at below 500 °C. Most of the nickel oxide particles are reduced at temperatures of 300~400 °C, corresponding to the large NiO particles outside the supports, having a low interaction with the supports [36]. The reduction peaks of NiO particles appearing in the wide temperature range might be due to the various metal-support interactions resulting in diverse sizes of NiO particles as shown in TEM images (20 to 100 nm) [37]. In the bi-metallic catalysts (NiMo/CBV-720 and NiMo/WSY-60H), the H2-TPR profiles are complex, which might be attributed to the metal-support interaction and distribution of the metallic species on the supports. It also might come from the two-step reduction of MoO3, which is firstly reduced to MoO2 and secondly transferred to metallic Mo. In particular, the H2-TPR profiles of the bimetallic catalysts can be divided into three regions, including the peaks below 400 °C, in the range of 400–650 °C, and above 650 °C. The superior H2 consumption below 400 °C is attributed to the reduction of the large NiO and MoO3 particles, which have a weak interaction with zeolite supports. The NiO species that have a strong interaction with the zeolite supports are reduced in the range of 400–650 °C. The MoO2 particles are reduced to metallic molybdenum at a high temperature of 700 °C [38,39]. On the other hand, the surfactant-added catalysts (S60/NiMo/CBV-720 and S60/NiMo/WSY-60) exhibit two reduction peaks: one huge peak in the wide temperature range of 300–600 °C and the other sharp peak at above 700 °C. The first peak is assigned to the reduction of NiO and MoO3 species in the catalysts while the second peak can be attributed to the reduction of MoO2 to metallic molybdenum. It is noticed that the reduction peak of NiO particles shifts to a higher temperature, indicating the high dispersion of Ni species inside the pores, making the strong metal–support interaction. The addition of Span60 surfactant significantly suppresses the aggregation of the metallic species, decreases the particle size, and enhances the dispersion of metal particles as well as facilitates the well-mixing of Ni and Mo particles inside the pores. As a result, a single reduction peak at 450 °C occurred in the H2-TPR profiles of the catalysts with the presence of Span60.

3. Materials and Methods

3.1. Materials

All chemicals were used to synthesize the catalysts without further purification or modification. The Ni-Mo catalysts were synthesized using chemical salts, nickel nitrate hexahydrate [Ni(NO3)2·6H2O, Sigma-Aldrich, St. Louis, MO, USA], and sodium molybdate dihydrate [Na2MoO4·2H2O]. Sorbitan stearate [Span60 (non-ionic), C24H46O6, Sigma-Aldrich] was used as a surfactant to highly distribute the Ni and Mo particles. Powder-type dealuminated Y zeolites (CBV-720) were obtained from Zeolyst (Valley Forge, PA19482, USA), and other dealuminated Y zeolites (WSY-60H) were purchased from Vision Chemical (Shanghai, China).

3.2. Catalyst Preparation

The MI and SAMI methods were employed to synthesize the Ni-based catalyst and NiMo-based catalysts. First, an appropriate quantity of nickel precursor corresponding to 5 wt.% Ni was gently ground with 1.00 g of the supports (CBV-720 or WSY-60H) in a mortar, followed by adding a proper amount of Na2MoO4·2H2O. The obtained catalysts containing 5 wt.% Ni and 10 wt.% Mo were denoted as NiMo/X, where X is the catalyst supports. When the catalyst was synthesized using the SAMI method, non-ionic surfactant Span60 was added during the grinding procedure. The catalysts prepared with Span60 were called S60/NiMo/X. According to the grinding procedure, when a homogenously colored mixture was obtained, the materials were moved to the alumina crucible and calcined. The calcination program was as follows: First, the materials were calcined at 80 °C for 24 h. Subsequently, the materials were calcined at 100 °C for 3 h. Finally, the materials were calcined at 300 °C for 2 h.
For the Ni-based catalyst synthesis, the molybdenum precursor was unused and only the nickel precursor was ground with the supports in a mortar. All procedures completely correspond with the preparation procedure of the NiMo-based catalyst, and the nickel precursor was used for the Ni 5 wt.%. The Ni-based catalyst was called Ni/X.

3.3. Characterization

All the catalyst characterizations, except of H2-TPR, were carried out with reduced catalysts. Catalyst reduction was carried out at 400 °C for 2 h in a muffle furnace.
Ex situ XRD patterns of NiMo- and Ni-based catalysts were obtained on an X-ray diffractometer (EMPyrean, Malvern PANalytical Ltd, Malvern, UK). The diffractometer was equipped with a Cu X-ray tube (Kα radiation, λ = 0.15418 nm) and a 3D PIXcel detector (PIXcel 3D with prefix interface, Xenon proportional detector, 0D point detector)). The analysis was performed at 1.8 kW. The catalysts were measured for 10 min with 0.013° per step. The peaks were assigned by comparison with JCPDS.
The HR-TEM and HAADF-STEM images were recorded on a JEM-3010 analytical electron microscope operated at an acceleration voltage of 200 kV, along with energy dispersive spectroscopy, to determine the morphology of NiMo catalysts. The procedure for preparing samples for TEM measurement was as follows: A few grams of NiMo catalysts were migrated to 1.0 mL anhydrous ethanol (above 99.95%, DUKSAN PURE CHEMICALS, Ansan-si, Republic of Korea) and sonicated for 100 min, then a few droplets were deposited on a Cu TEM grid.
The BET method was used to investigate the N2 adsorption–desorption at −196 °C on a Tristar Ⅱ 3020 analyzer and BJH analysis was employed to obtain the pore size distribution from the N2 adsorption branch.
The H2-TPR was performed on an AutoChem 2920 V4.03 (Micromeritics, Norcross, USA) equipped with a fixed-bed reactor and a thermal conductivity detector. The samples of 50 mg were pre-treated at 200 °C under pure Ar gas flow and cooled to 50 heated °C only using fans. The temperature was then heated from 50 to 850 °C under 5.0% H2/Ar flow in 50 sccm.

3.4. Catalytic Performance Test

All catalytic activity tests were conducted in a 250 mL-batch reactor. The WPPO, distilled at 200 °C, was mixed with 5 wt.% dimethyl disulfide (Sigma-Aldrich, 99.0%) as a sulfidation agent. For the HDT of WPPO, the reactor was loaded with 0.07 g catalysts and 35.0 g mixed solution and pressurized to 6.0 MPa H2 at 25 °C. Then, the temperature was ramped to 400 °C at a heating rate of 10 °C/min and was maintained for 4 h with a 1500 rpm stirring rate. The catalytic activity test over the commercial Ni-Mo catalyst was performed in similar conditions for comparison.
The impurity contents of WPPO used in this reaction study were 118.6 wppm for sulfur, 2291.6 wppm for nitrogen, and 300.0 wppm for chlorine. The nitrogen and sulfur contents were analyzed using a total nitrogen sulfur analyzer (NSX-2100V, Mitsubishi, Tokyo, Japan). The chlorine contents were determined using an X-ray fluorescence instrument (X-Supreme 8000, Oxford instruments, Abingdon, UK).

4. Conclusions

Effective catalysts for treating impurities in the WPPO by way of the HDT process were synthesized using the MI and SAMI methods. These catalysts were supported on two distinct zeolite supports—CBV-720 and WSY-60H. Chlorine conversion occurred completely over NiMo catalysts prepared using both the MI and SAMI methods, as well as commercial NiMo catalysts. Consequently, we conclude that employing MI and SAMI methods for preparing HDCl catalysts is preferable.
The addition of Span60 during the catalyst synthesis procedure facilitated the impregnation of NiMo particles into the supports, ensuring a well-distributed catalyst. The catalyst with Span60 exhibited a better catalytic performance than the one without Span60. The bimetallic NiMo-based catalysts with Span60 exhibited a significant improvement in HDN activity, removing more than 94% of sulfur and 85% of nitrogen in the WPPO, whereas those without Span60 reduced around 92% of the sulfur and 76% of the nitrogen. The enhanced performance of the catalysts in the presence of Span60 was attributed to the high dispersion of NiMo particles, leading to the mitigation of the segregation of Ni species during the sulfidation process, the creation of smaller active sites in size, and a higher number of Ni–Mo interfaces. The Span60 enhanced the Ni dispersion and facilitated the production of more Ni–Mo interfaces. On the other hand, since the SAMI method is not suitable for directly manufacturing catalysts in pellet form, an appropriate extrusion technique should be employed for future industrial use.

Author Contributions

Conceptualization, E.H.C., S.-G.J. and C.H.K.; Methodology, E.H.C.; validation, E.H.C. and B.S.Y.; formal analysis, E.H.C. and B.S.Y.; investigation, E.H.C. and K.-D.K.; resources, S.-G.J. and C.H.K.; data curation, E.H.C., K.-D.K. and B.S.Y.; writing—original draft preparation, E.H.C., K.-D.K., B.S.Y., E.C. and Y.J.Y.; writing—review and editing, B.S.Y.; visualization, E.H.C., K.-D.K., B.S.Y., E.C. and Y.J.Y.; supervision, T.N.P., S.-G.J. and C.H.K.; project administration, S.-G.J. and C.H.K.; funding acquisition, S.-G.J. and C.H.K. All authors have read and agreed to the published version of the manuscript.

Funding

This research was supported by the Technology Innovation Program (or Industrial Strategic Technology Development Program) (20015430, 1415186232) funded by the Ministry of Trade, Industry & Energy (MOTIE, Republic of Korea). This work was also supported by the Technology Innovation Program (RS-2023-00265608, 1415188462) funded by the Ministry of Trade Industry & Energy (MOTIE, Republic of Korea).

Data Availability Statement

Data are contained within the article..

Conflicts of Interest

The authors declare no conflict of interest.

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Catalysts 13 01476 g001
Figure 1. S, N, and Cl conversion over NiMo-Com, NiMo/CBV-720, S60/NiMo/CBV-720, NiMo/WSY-60H, and S60/NiMo/WSY-60H catalysts at 400 °C.
Figure 1. S, N, and Cl conversion over NiMo-Com, NiMo/CBV-720, S60/NiMo/CBV-720, NiMo/WSY-60H, and S60/NiMo/WSY-60H catalysts at 400 °C.
Catalysts 13 01476 g001
Catalysts 13 01476 g002
Figure 2. XRD patterns of NiMo supported CBV-720 (a) and WSY-60H (b) catalysts.
Figure 2. XRD patterns of NiMo supported CBV-720 (a) and WSY-60H (b) catalysts.
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Catalysts 13 01476 g003
Figure 3. Nitrogen adsorption–desorption isotherms and pore size distributions of NiMo catalysts on two distinct zeolite supports: (a,b) on the CBV 720 support, (c,d) on the WSY-60H support.
Figure 3. Nitrogen adsorption–desorption isotherms and pore size distributions of NiMo catalysts on two distinct zeolite supports: (a,b) on the CBV 720 support, (c,d) on the WSY-60H support.
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Catalysts 13 01476 g004
Figure 4. TEM and mapping images of NiMo catalysts on two distinct supports: (a) 5Ni/CBV-720, (b) 5Ni10Mo/CBV-720, (c) S60/5Ni10Mo/CBV-720, (d) 5Ni/WSY-60H, (e) 5Ni10Mo/WSY-60H, and (f) S60/5Ni10Mo/WSY-60H.
Figure 4. TEM and mapping images of NiMo catalysts on two distinct supports: (a) 5Ni/CBV-720, (b) 5Ni10Mo/CBV-720, (c) S60/5Ni10Mo/CBV-720, (d) 5Ni/WSY-60H, (e) 5Ni10Mo/WSY-60H, and (f) S60/5Ni10Mo/WSY-60H.
Catalysts 13 01476 g004
Catalysts 13 01476 g005
Figure 5. H2-TPR spectra of catalysts calcined at 300 °C: (a) CBV-720 supported catalysts, (b) WSY-60H supported catalysts.
Figure 5. H2-TPR spectra of catalysts calcined at 300 °C: (a) CBV-720 supported catalysts, (b) WSY-60H supported catalysts.
Catalysts 13 01476 g005
Table 1. N2 adsorption–desorption data of USY supports and NiMo-based catalysts.
Table 1. N2 adsorption–desorption data of USY supports and NiMo-based catalysts.
BET Surface Area a
[A, m2 g−1]		Total Pore Volume b
[Vp, cm3 g−1]		Average Pore Diameter c
[dp, nm]
Pure CBV 7209300.562.4
Ni/CBV 7209500.572.4
NiMo/CBV 7206300.442.8
S60/NiMo/CBV 7205300.362.7
Pure WSY-60H8200.552.6
Ni/WSY-60H8600.602.8
NiMo/WSY-60H4700.342.9
S60/NiMo/WSY-60H5300.362.8
a Estimated from N2 adsorption at −196 °C; b Calculated from p/p0 = 0.990; c 4Vp/A.
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Cho, E.H.; Kim, K.-D.; Yoon, B.S.; Cho, E.; Yu, Y.J.; Phan, T.N.; Jeon, S.-G.; Ko, C.H. Efficient Synthesis of Nickel-Molybdenum/USY-Zeolite Catalyst for Eliminating Impurities (N, S, and Cl) in the Waste Plastic Pyrolysis Oil: Dispersion Effect of Active Sites by Surfactant-Assisted Melt-Infiltration. Catalysts 2023, 13, 1476. https://doi.org/10.3390/catal13121476

AMA Style

Cho EH, Kim K-D, Yoon BS, Cho E, Yu YJ, Phan TN, Jeon S-G, Ko CH. Efficient Synthesis of Nickel-Molybdenum/USY-Zeolite Catalyst for Eliminating Impurities (N, S, and Cl) in the Waste Plastic Pyrolysis Oil: Dispersion Effect of Active Sites by Surfactant-Assisted Melt-Infiltration. Catalysts. 2023; 13(12):1476. https://doi.org/10.3390/catal13121476

Chicago/Turabian Style

Cho, Eui Hyun, Ki-Duk Kim, Byung Sun Yoon, Eunkyung Cho, Yeon Jeong Yu, Tuan Ngoc Phan, Sang-Goo Jeon, and Chang Hyun Ko. 2023. "Efficient Synthesis of Nickel-Molybdenum/USY-Zeolite Catalyst for Eliminating Impurities (N, S, and Cl) in the Waste Plastic Pyrolysis Oil: Dispersion Effect of Active Sites by Surfactant-Assisted Melt-Infiltration" Catalysts 13, no. 12: 1476. https://doi.org/10.3390/catal13121476

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