Synergy Effects in a Bimetallic Ru ─ Pt Alloy Catalyst for Low‐H₂‐Pressure Hydrogenolysis of Low‐Density Polyethylene

Abstract

Hydrogenolysis of low‐density polyethylene (LDPE) under low pressure of H₂ has been accomplished with a Ru─Pt bimetallic alloy catalyst. Using Ru₅Pt₁/CeO₂ (atomic ratio of Ru to Pt is 5:1) as a catalyst, LDPE was efficiently converted (97.6 ± 2.5% conversion) to gas and liquid hydrocarbons under 5 bar of H₂ at 200 °C, whereas Ru/CeO₂ and Pt/CeO₂ showed much lower conversion (45.7 ± 3.7% and < 1%, respectively), under the same conditions. Mechanistic studies suggested that the higher activity of Ru₅Pt₁/CeO₂ can be attributed to the synergistic effect of Ru (cleavage of C─C bond) and Pt (acceleration of Ru─alkyl hydrogenation step) on the catalyst surface.

A Ru─Pt bimetallic alloy catalyst enables efficient hydrogenolysis of LDPE under low H₂ pressure. The catalyst outperforms monometallic Ru or Pt, with enhanced activity attributed to the synergy of Ru (C─C bond cleavage) and Pt (hydrogenation of Ru─alkyl intermediates).

1. Introduction

Chemical conversion of polyethylene (PE) has been intensively studied in the last decade as a promising recycling process of plastic wastes.^{[ 1} , ^{2 ]} PE backbone is linked by numerous C─C bonds, which are too stable to break down in nature.^{[ 3} , ^{4 ]} Thus, PE induces a more serious threat to the environment compared to other plastics connected by C─X (X = O, N, S) bonds.^{[ 5 ]} Hydro‐conversion of PE via hydrogenolysis or hydrocracking reaction assisted by a heterogeneous catalyst has been intensively studied since it is advantageous to avoid coking, the major problem in the conventional thermal cracking.^{[ 6} , ^{7 ]} Recently, hydrogenolysis has been paid much attention because it proceeds under milder conditions with less likely production of coke, contributing to enhancement of catalyst durability.^{[ 8 ]} For PE hydrogenolysis using a heterogeneous catalyst, Ru is the metal of choice owing to its tendency to cleave C─C bond more efficiently compared to other metals.^{[ 7} , ⁹ , ¹⁰ , ¹¹ , ¹² , ^{13 ]} The Ru‐catalyzed hydrogenolysis of PE produces various alkane products containing gases, liquid oils, or lubricants.^{[ 14} , ¹⁵ , ¹⁶ , ¹⁷ , ^{18 ]}

In general, PE hydrogenolysis using Ru‐based catalysts requires high pressure of H₂ (Figure 1a). In a very recent report, low‐density PE (LDPE) hydrogenolysis under mild conditions at 180 °C using supported Ru nanoparticles was achieved, however, it requires 10–20 bar of H₂.^{[ 19 ]} In most reported cases, ≥20 bar of H₂ is necessary, and the highest activity is obtained under 30–40 bar (see Table S1).^{[ 14} , ²⁰ , ²¹ , ²² , ²³ , ²⁴ , ²⁵ , ²⁶ , ²⁷ , ²⁸ , ^{29 ]} Although the detailed reaction mechanism is still unclear, the C─C bond cleavage step (Figure 1b(i)) and the Ru─alkyl hydrogenation step on the catalyst surface (Figure 1b(ii)) have been proposed to be two key steps for PE hydrogenolysis.^{[ 24} , ^{26 ]} In the case of Ru, it is likely that the latter step is responsible for the requirement of high H₂ pressure.^{[ 24 ]} We envisioned that, Pt would be an effective metal to facilitate the hydrogenation step under low pressure of H₂, since Pt is known to be a metal with high activity for hydrogenation reactions^{[ 30 ]} (Figure 1b(iii)).

Figure 1.

a) Hydrogenolysis of PE over conventional Ru‐based catalysts. b) Two key steps of the C─C bond hydrogenolysis (i, ii) and our strategy (iii). c) This work: Ru─Pt alloy catalyst for hydrogenolysis of LDPE under low pressure of H₂.

Herein, we report a Ru─Pt bimetallic catalyst for efficient hydrogenolysis of LDPE at low pressure of H₂ (Figure 1c). While preparing this paper, Hu et al. reported a significant advancement using a Pt‐rich Ru alloy catalyst, which achieved low methane selectivity under 5 bar H₂ at 250–300 °C.^{[ 31 ]} In contrast, in this work, the hydrogenolysis of PE using our Ru‐rich Pt alloy catalyst was carried out under 5 bar H₂ and at a lower temperature of 200 °C. Mechanistic studies suggested that the synergistic promotion of hydrogenation step of the Ru─alkyl intermediate by Pt was the key for the low‐pressure hydrogenolysis using the Ru─Pt alloy catalyst.

2. Results and Discussion

2.1. Hydrogenolysis of LDPE

Supported Ru─Pt bimetallic catalysts on various metal oxides such as CeO₂,^{[ 31 ]} Al₂O₃, SiO₂, and ZrO₂ ^{[ 32 ]} were prepared by an incipient wetness impregnation method using RuCl₃ and H₂PtCl₆ as metal precursors. The catalysts were pre‐treated under 1 bar of H₂ at 300 °C for 2 hours to reduce the deposited metal species prior to use in the hydrogenolysis of LDPE. (The catalysts are designated as Ru _x Pt _y /support, where x is the weight% of Ru with respect to the support and x/y is the atomic ratio of Ru to Pt; see Supporting Information for the details of the preparation of the catalysts). The LDPE (Mn = 10,100, Mw = 105,600) hydrogenolysis was performed under 5 bar of H₂ at 200 °C for 12 hours. After the reaction, the gas phase (C1–C4) was analyzed by GC. Then, the liquid products (C5–C35) were extracted by dichloromethane (DCM) followed by GC analysis to determine the product yields. The solid residue insoluble in DCM (solid product, the catalyst, and unreacted LDPE) was collected and dried, then weighed to determine the solid conversion (wt%) = 100% × (weight of LDPE before reaction−(weight of recovered solid − weight of catalyst))/weight of LDPE before reaction (see Supporting Information for the details of hydrogenolysis reaction). The solid conversions and product yields (wt%) from the hydrogenolysis of LDPE using various catalysts are presented in Figure 2. Hereafter, catalytic activity is evaluated based on solid conversion. When employing the bimetallic Ru₅Pt₁/CeO₂ catalyst under 5 bar of H₂, the solid conversion increased with reaction time (Figure S1), reaching near‐complete conversion (97.6 ± 2.5%) after 12 hours (Figure 2, entry 1). A loss in mass balance was observed after 3–12 hours of hydrogenolysis, but not after 24 hours (Figure S1). These findings suggest that the mass balance loss is likely due to the formation of ≥ C36 alkanes, which are extracted into DCM but undetectable by GC analysis. These undetectable long‐chain alkanes subsequently underwent further hydrogenolysis, forming shorter‐chain alkanes. As a result, nearly 100% mass balance was achieved when the reaction time was extended to 24 hours (Figure S1). Furthermore, excessive hydrogenolysis led to an increased yield of C1–C4 alkanes after 24 hours (Figure S1). Monometallic Ru/CeO₂ resulted in lower solid conversion (45.7 ± 3.7%) while Pt/CeO₂ showed no conversion (Figure 2, entries 2 and 3). A physical mixture of Ru/CeO₂ and Pt/CeO₂ resulted in lower conversion (Figure 2, entry 4) than Ru₅Pt₁/CeO₂. Thus, coexistence of Ru and Pt species on the same CeO₂ support contributes to the increase of solid conversion, and the synergy between Ru and Pt is crucial for the high activity of Ru₅Pt₁/CeO₂. The ratio of Ru to Pt was also investigated, however, it less affects catalytic activity (Figure S2). Ru₅Pt₁ supported on other metal oxides (Al₂O₃, SiO₂, and ZrO₂) was much less active than Ru₅Pt₁/CeO₂ (Figure 2, entries 5, 6, and 7). The product distributions of all experiments are summarized in Figure S3.

Figure 2.

LDPE hydrogenolysis using various catalysts. Reaction conditions: LDPE (0.5 g), catalyst (0.1 g for entries 1–3 and 5–7, a physical mixture of Ru/CeO₂ (0.1 g) and Pt/CeO₂ (0.1 g) for entry 4), 200 °C, H₂ (5 bar), and 12 hours. Solid conversion (wt%) = 100% × (weight of LDPE before reaction−(weight of recovered solid − weight of catalyst))/weight of LDPE before reaction. Yield of Ci (wt%) = 100% × (weight of Ci alkane product/weight of LDPE before reaction), where i is the number of carbons in alkane. The results are presented as mean ± standard deviation from two independent experiments, and Pt/CeO₂ has no error bars.

2.2. Characterization of the Catalysts

Characterization of the catalyst was carried out (Figures 3 and S4–S13 and Tables S2 and S3). High‐angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM) and energy‐dispersive X‐ray spectroscopy (EDS) analyses of the Ru₅Pt₁/CeO₂ catalyst, which showed the highest activity, suggested that Ru─Pt alloys were formed on the CeO₂ support since both Ru and Pt EDS signals appeared in the same region (Figure 3a,b), and that the average particle size was approximately 2.4 nm (Figure S5c,d). No apparent diffraction peaks attributable to Ru or Pt were observed in powder X‐ray diffraction (XRD) pattern, indicating the Ru─Pt alloy nanoparticles are finely dispersed on the CeO₂ support (Figure 3c). X‐ray absorption near‐edge structure (XANES) and k ³‐weighted Fourier transforms of the extended X‐ray absorption fine structure (EXAFS) oscillations of Ru₅Pt₁/CeO₂ and reference samples are shown in Figure 3d,e. The Ru K‐edge XANES spectrum of Ru₅Pt₁/CeO₂ resembled in shape to that of Ru powder, supporting the formation of metallic Ru⁰ (Figure 3d). Pt L₃‐edge XANES spectrum of Ru₅Pt₁/CeO₂ was similar to that of Pt foil (Figure 3e), suggesting most of the Pt species are in metallic Pt⁰ state in the alloy nanoparticles. Fourier‐transformed EXAFS (FT‐EXAFS) with fitting data is shown in Figure 3f,g, and the structural parameters obtained from the curve‐fitting analysis of EXAFS are summarized in Tables S2 and S3. The Ru K‐edge FT‐EXAFS of Ru₅Pt₁/CeO₂ displayed a single peak assignable to the Ru─Ru bonds. The fitting result of the Pt L₃‐edge FT‐EXAFS of Ru₅Pt₁/CeO₂ revealed the presence of both the Pt─Ru and Pt─Pt bonds with coordination numbers of 3.7 and 4.8, respectively (Table S3). In the case of close‐packed structure, coordination number of Ru or Pt atom is 12. In Ru₅Pt₁/CeO₂, the sum of the coordination numbers for Pt─Ru and Pt─Pt bonds is approximately 8.5, which is lower than 12. This suggests that the Pt species are primarily incorporated within individual Ru nanoparticles, with a portion located on the surface of the alloy nanoparticles, as inferred from the Pt L₃‐edge FT‐EXAFS analysis.^{[ 33 ]} In Ru 3p X‐ray photoelectron spectroscopy (XPS) spectra, the fitting peaks attributable to Ru⁰ (461.7/483.8 eV for Ru₅Pt₁/CeO₂ and 462.0/484.1 eV for Ru/CeO₂) and Ru ^{δ +} (464.0/486.2 for Ru₅Pt₁/CeO₂ and 465.4/487.5 eV for Ru/CeO₂) were observed (Figure 3h).^{[ 34 ]} XPS spectrum of Ru₅Pt₁/CeO₂ in Pt 4f region can be deconvoluted into two components at 71.4 and 74.9 eV for Pt⁰, and 72.8 and 76.1 eV for Pt²⁺ species (Figure 3i).^{[ 35 ]}

Figure 3.

Characterization of the catalysts. a) EDS mapping of Ce (blue), Ru (purple), and Pt (yellow) elements of Ru₅Pt₁/CeO₂. b) Overlap of EDS elemental map of Ce, Ru, and Pt of Ru₅Pt₁/CeO₂. c) Powder XRD pattern of Ru₅Pt₁/CeO₂ and powder diffraction files of Ru metal (#1 539 052) and Pt metal (#8801). d) Ru K‐edge XANES spectra of Ru₅Pt₁/CeO₂ and reference samples. e) Pt L₃‐edge XANES spectra of Ru₅Pt₁/CeO₂ and reference samples. f) k ³‐weighted Fourier transforms of Ru K‐edge EXAFS spectra of Ru₅Pt₁/CeO₂ and reference samples. g) k ³‐weighted Fourier transforms of Pt L₃‐edge EXAFS spectra of Ru₅Pt₁/CeO₂ and reference samples. Solid and dotted lines in panels f), g) represent raw data and fitted results, respectively. h) Ru 3p XPS spectra of Ru₅Pt₁/CeO₂ and Ru/CeO₂. i) Pt 4f XPS spectrum of Ru₅Pt₁/CeO₂. Black solid lines with circle plots and other solid lines in Figures h),i) indicate raw spectra and deconvoluted peaks, respectively.

Characterization of the corresponding single metallic Ru/CeO₂ was also carried out. As revealed by TEM observation, Ru nanoparticles with an average size of 2.1 nm were dispersed on the CeO₂ support (Figure S5g,h). From XANES (Figure S12a), FT‐EXAFS (Figure S12b), and XPS (Figure 3h), the Ru species mainly exist as metallic Ru⁰ state. Given the similar particle sizes (Figure S5) and electronic states (Figure 3h) of the supported Ru species in Ru/CeO₂ and Ru₅Pt₁/CeO₂, the higher catalytic activity of Ru₅Pt₁/CeO₂ for LDPE hydrogenolysis can be attributed to the promotional effect of the Pt species. From the experimental results shown in Figure 2, the physical mixture of Ru/CeO₂ and Pt/CeO₂ exhibited slightly higher conversion than Ru/CeO₂ alone. To investigate this, we performed STEM–EDS analysis of the physical mixture after the hydrogenolysis of LDPE, which revealed partial formation of Ru─Pt alloy, likely induced by the mechanical stirring of the two catalysts (Figure S8). This partial alloy formation may account for the slightly higher conversion observed with the physical mixture.

For other supports, different coordination numbers for Pt─Ru and Pt─Pt bonds were observed in Ru₅Pt₁/Al₂O₃ and Ru₅Pt₁/SiO₂ (Table S3). Moreover, no alloy formation was detected in Ru₅Pt₁/ZrO₂ (Figure S11). These structural differences are therefore likely responsible for the superior catalytic activity of Ru₅Pt₁/CeO₂.

2.3. Characterization of the Spent Catalyst and Reuse Experiments

After 24 hours of hydrogenolysis, the recovered Ru₅Pt₁/CeO₂ catalyst was subjected to STEM analysis. The size distribution of nanoparticles obtained from STEM image showed the presence of slightly larger particles; however, the average particle size did not change substantially (Figure S14a,b). The EDS signals of Ru and Pt overlapped in the same regions, indicating that alloy formation was maintained after the hydrogenolysis reaction (Figure S14c–h). In addition, the electronic states of Ru and Pt were not significantly changed (Figure S14i,j). The Ru₅Pt₁/CeO₂ catalyst could be reused at least three times, although the overall solid conversion gradually decreased with each reuse (Figure S15). From the first reuse experiment onward, the fraction of undetectable components (≥C36 alkanes) increased, suggesting a decrease in the number of C─C bond cleavages.

2.4. Effect of H₂ Pressure on Hydrogenolysis and Mechanistic Insights

The H₂ pressure dependency of the catalytic activity revealed that Ru₅Pt₁/CeO₂ showed the highest activity under 5 bar of H₂ and the conversion was > 90% in the range of 5–30 bar (Figure 4a). The product distributions are summarized in Figures S16 and S17. A further increase of H₂ pressure to 40 bar resulted in the activity decrease (Figure 4a). On the other hand, Ru/CeO₂ showed the highest conversion under 20 bar of H₂ and a further increase of H₂ pressure resulted in a decrease of the solid conversion (Figure 4b). The activity decrease under higher pressure of H₂ is likely due to the higher surface hydrogen coverage leading to prevention of LDPE adsorption on the catalyst surface.^{[ 20} , ^{21 ]} In other words, the catalyst poisoning by the surface hydride species is the reason for the lower activity under higher pressure of H₂. Nevertheless, Ru₅Pt₁/CeO₂ showed higher activity than Ru/CeO₂ under the examined range of H₂ pressure.

Figure 4.

LDPE hydrogenolysis under various pressures of H₂ using a) Ru₅Pt₁/CeO₂ and b) Ru/CeO₂. Reaction conditions: LDPE (0.5 g), catalyst (0.1 g), 200 °C, H₂ (1–40 bar), and 12 hours. The yields of C1, C2–C4, and C5–C35 were determined by GC analysis. Solid conversion (wt%) = 100% × (weight of LDPE before reaction−(weight of recovered solid − weight of catalyst))/weight of LDPE before reaction. Yield of Ci (wt%) = 100% × (weight of Ci alkane product/weight of LDPE before reaction), where i is the number of carbons in alkane. The results are presented as mean ± standard deviation from two independent experiments, and 1 bar has no error bars.

To elucidate the role of Pt in Ru₅Pt₁/CeO₂ for C─C bond hydrogenolysis, the hydrogenolysis of docosane (C₂₂H₄₆), a shorter analogue of PE and thus easier to analyze the products, under different conditions was carried out. The conversion and product yields for the hydrogenolysis of docosane by Ru₅Pt₁/CeO₂ or Ru/CeO₂ are shown in Figure 5a,b (the normalized results are presented in Figure S18, and the corresponding carbon number distributions of the products are shown in Figures S19 and S20). As a result, Ru₅Pt₁/CeO₂ exhibited higher conversion than Ru/CeO₂ under the examined H₂ pressures (Figure 5a vs. 5b). Both catalysts showed the highest conversion under 5 bar of H₂ then the conversion decreased with an increase of the H₂ pressure. This is likely due to inhibition of substrate adsorption by hydrogen coverage on the catalyst surface at higher pressures of H₂.^{[ 20} , ^{21 ]} Figure 5c shows the number of C─C bond cleavages estimated from the results of hydrogenolysis of docosane (see Supporting Information for detailed calculation methods). The number of C─C bond cleavages over Ru₅Pt₁/CeO₂ was larger than that over Ru/CeO₂, indicating the higher activity of Ru₅Pt₁/CeO₂ under the same H₂ pressure. We also compared the product yields under conditions of comparable docosane conversion. Ru/CeO₂ achieved a conversion of 86.0 ± 5.0% after 120 minutes of hydrogenolysis, whereas Ru₅Pt₁/CeO₂ reached 82.7 ± 1.1% conversion in just 45 minutes (Figure S21a,b). At these similar levels of conversion, methane yields were 10.3 ± 1.2% for Ru₅Pt₁/CeO₂ and 20.8 ± 2.2% for Ru/CeO₂, respectively. These results suggest that methane formation was more effectively suppressed by Ru₅Pt₁/CeO₂ compared to Ru/CeO₂. Additionally, for Ru₅Pt₁/CeO₂, the estimated number of C─C bond cleavages and the ratio of methane formation, defined as 100% × (the number of methane/the number of C─C bond cleavages), were shown in Figure S21c,d, respectively. The ratio of methane formation is independent of the conversion (Figure S21d). Under 5 bar of H₂, Ru/CeO₂ resulted in a higher ratio of methane than Ru₅Pt₁/CeO₂ (Figure S21e), suggesting that methane was generated more easily on Ru/CeO₂. For the hydrogenolysis of PE, if terminal C─C bond cleavage was predominant, a greater number of C─C bond cleavages would lead to higher methane production. However, RuPt/CeO₂ exhibited a higher number of C─C bond cleavages than Ru/CeO₂, while producing less methane. This observation indicates that internal/random C─C bond cleavage is more favorable than terminal cleavage over the RuPt/CeO₂ catalyst.^{[ 24} , ^{26 ]}

Figure 5.

Hydrogenolysis of docosane over a) Ru₅Pt₁/CeO₂ and b) Ru/CeO₂ under various pressures of H₂. Reaction conditions: docosane (0.5 g), catalyst (0.1 g), 200 °C, H₂ (1–40 bar), 1 hour. The yields of C1, C2–C4, and C5–C21 were determined by GC analysis. Conversion (%) = 100% × (initial M_C22 − M_C22)/initial M_C22. C yield (%) = 100% × (M_{C i}  × i)/(initial M_C22 × 22), where i is the number of carbons in alkane, M_{C i} is the moles of C _i alkane, and initial M_C22 is the moles of C₂₂H₄₆ before reaction. c) The estimated number of C─C bond cleavages for the hydrogenolysis of docosane under various pressures of H₂. The number of C─C bond cleavages = (${\sum }_{i=1}^{22}{M}_{Ci}$−initial M_C22) ×N_A, N_A is Avogadro constant (6.02214076 × 10²³). The results of Ru/CeO₂ under H₂ (5 bar) are presented as mean ± standard deviation from eight independent experiments, and the other results are presented as mean ± standard deviation from two independent experiments. 1 bar has no error bars. Plausible mechanisms for the hydrogenolysis of long‐chain alkane substrate over (d) RuPt/CeO₂ and (e) Ru/CeO₂.

The higher hydrogenolysis activity and the lower ratio of methane formation when using Ru₅Pt₁/CeO₂ rather than Ru/CeO₂ as the catalyst can be explained as shown in Figure 5d,e. In both cases of Ru₅Pt₁/CeO₂ and Ru/CeO₂, the supported Ru species are mainly responsible for C─C bond cleavage (step (ii) in Figure 5d,e) because Ru/CeO₂ does promote the hydrogenolysis, while Pt/CeO₂ did not show any activity (Figure 2, entries 2 vs. 3). It is likely that the difference between the two systems originates from the hydrogenation step (step (iii)); that is, the surface Ru─alkyl species formed by C─C bond cleavage is hydrogenated by a neighboring hydrogen species (step (iii) in Figure 5d). Faster hydrogen delivery on the bimetallic Ru─Pt catalyst resulted in its higher activity and allowed the reaction to proceed at lower pressure of H₂. In addition, acceleration of step (iii) should result in the formation of longer alkane products because the alkyl species were hydrogenated and dissociated from the catalyst surface prior to the further consecutive C─C bond cleavage (steps (iv,v) in Figure 5e). Accordingly, Ru₅Pt₁/CeO₂ resulted in lower methane production. In contrast, due to the slower hydrogenation step in the case of Ru/CeO₂ (step (iii) in Figure 5e), C─C bonds are consecutively cleaved (steps (iv,v) in Figure 5e) to give shorter alkane products. Furthermore, as shown in Figure S3a–c, increasing the Pt ratio shifts the liquid product distribution toward shorter alkanes. This trend is likely due to the higher Pt content accelerating the hydrogenative desorption of Ru─alkyl intermediates, thereby promoting C─C bond hydrogenolysis.

Moreover, the synergy between Ru and Pt species on the bimetallic Ru─Pt catalyst was supported by density functional theory (DFT) calculations for the hydrogenation step (step (iii) in Figure 5d) employing a Ru─Pt surface model with a methyl group and H species on different adsorption sites (on Ru or Pt) (see Supporting Information for the details, Figures S22–S24). As a result, the pathway for the reaction of Ru─methyl with Pt─H has a lower activation energy than that of Ru─methyl with Ru─H, suggesting Pt species in Ru₅Pt₁/CeO₂ promote the hydrogenation step of surface metal alkyl species (step (iii) in Figure 5d). Therefore, it is likely that the C─C bond cleavage occurs on Ru, then surface hydrogen species is delivered from Pt to Ru─alkyl intermediate, corresponding to our hypothesis based on the experimental results.

3. Conclusion

In conclusion, we have developed a Ru─Pt bimetallic alloy catalyst for the hydrogenolysis of LDPE under low pressure of H₂. The catalytic activity of the bimetallic catalyst was higher than the corresponding single metallic Ru or Pt catalyst. Mechanistic studies suggested that the higher activity of the bimetallic catalyst can be attributed to the synergistic effect of Ru (cleavage of C─C bond) and Pt (acceleration of Ru─alkyl hydrogenation step) species on the catalyst surface.

Supporting Information

The authors have cited additional references within the Supporting Information.^{[ 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 , ⁶¹ , ⁶² , ⁶³ , ⁶⁴ , ⁶⁵ , ⁶⁶ , ⁶⁷ , ⁶⁸ , ⁶⁹ , ⁷⁰ , ⁷¹ , ^{72 ]} The Supporting Information includes detailed experimental procedures, carbon distributions of alkane products obtained from the hydrogenolysis of LDPE or docosane, characterization data of the catalysts, and additional details of the DFT calculations.

Conflicts of Interest

The authors declare no conflict of interest.

Supporting information

Supporting Information

Data Availability Statement

The data that support the findings of this study are available in the supplementary material of this article.