Parent Catalyst Research Articles

Gold-catalysed amine synthesis by reductive hydroamination of alkynes with nitroarenes.

Amines are the most pivotal class of organic motifs in pharmaceutical compounds. Here we provide a blueprint for a general synthesis of amines by catalyst differentiation enabled by triple Au-H/Au+/Au-H relay catalysis. The parent catalyst is differentiated into a set of catalytically active species to enable triple cascade catalysis, where each catalytic species is specifically tuned for one catalytic cycle. This strategy enables the synthesis of biorelevant amine motifs by reductive hydroamination of alkynes with nitroarenes. Using this triple cascade approach, we have achieved exceptional functional group tolerance, enabling the use of bulk chemical feedstocks as coupling partners for the amination of both simple and complex alkynes (>100 examples), including those derived from pharmaceuticals, peptides and natural products (>30 examples). The isolation and full crystallographic characterization of gold hydride and hydride-bridged gold complexes has garnered insights into the catalyst differentiation process of fundamental organometallic gold hydride complexes.

Bio-inspired copper complexes with Cu2S cores: (solvent) effects on oxygen reduction reactions.

The need for effective alternative energy sources and "green" industrial processes is a more crucial societal topic than ever. In this context, mastering oxygen reduction reactions (ORRs) is a key step to develop fuel cells or to propose alternatives to energy-intensive setups such as the anthraquinone process for hydrogen peroxide production. Achieving this goal using bio-inspired metal complexes based on abundant and non-toxic elements could provide an environmentally friendly option. Given the prevalence of Cu-containing active sites capable of reductive activation of dioxygen in nature, the development of Cu-based catalysts for the ORR thus appears to be a relevant approach. We herein report the preparation, full characterization and (TD)DFT investigation of a new dinuclear mixed-valent copper complex 6 exhibiting a Cu2S core and a bridging triflate anion. Its ORR activity was compared with that of its parent catalyst 1. Two types of solvents were used, acetonitrile and acetone, and various catalyst/Me8Fc (electron source) ratios were tested. Our results highlight a counterintuitive solvent effect for 1 and a drastic drop in the activity for 6 in coordinating acetonitrile together with the modification of its chemical structure.

Single-Atom Alloy Formation via Reaction-Driven Catalyst Restructuring.

We demonstrate that single-atom alloy catalysts can be made by exposing physical mixtures of monometallic supported Cu and Pd catalysts to vinyl acetate (VA) synthesis reaction conditions. This reaction induces the formation of mobile clusters of metal diacetate species that drive extensive metal nanoparticle restructuring, leading to atomic dispersion of the precious metal, smaller nanoparticle sizes than the parent catalysts, and high activity and selectivity for both VA synthesis and ethanol dehydrogenation reactions. This approach is scalable and appears to be generalizable to other alloy catalysts.

Boron-Induced Interstitial Effects Drive Water Oxidation on Ordered Ir-B Compounds.

Interstitial filling of light atoms strongly affects the electronic structure and adsorption properties of the parent catalyst due to ligand and ensemble effects. Different from the conventional doping and surface modification, constructing ordered intermetallic structures is more promising to overcome the dissolution and reconstruction of active sites through strong interactions generated by atomic periodic arrangement, achieving joint improvement in catalytic activity and stability. However, for tightly arranged metal lattices, such as iridium (Ir), obtaining ordered filling atoms and further unveiling their interstitial effects are still limited by highly activated processes. Herein, we report a high-temperature molten salt assisted strategy to form the intermetallic Ir-B compounds (IrB1.1) with ordered filling by light boron (B) atoms. The B residing in the interstitial lattice of Ir constitutes favorable adsorption surfaces through a donor-acceptor architecture, which has an optimal free energy uphill in rate-determining step (RDS) of oxygen evolution reaction (OER), resulting in enhanced activity. Meanwhile, the strong coupling of Ir-B structural units suppresses the demetallation and reconstruction behavior of Ir, ensuring catalytic stability. Such B-induced interstitial effects endow IrB1.1 with higher OER performance than commercial IrO2, which is further validated in proton exchange membrane water electrolyzers (PEMWEs).

Tailored HZSM-5 catalyst modification via phosphorus impregnation and mesopore introduction for selective catalytic conversion of polypropylene into light olefins

The waste polyolefin composition varies regionally due to different sorting technologies, emphasizing the necessity for a robust catalyst capable of selectively converting pyrolysis vapors into valuable light olefins while maintaining stability. HZSM-5, a microporous catalyst, efficiently cracks polyethylene (PE) pyrolysis vapors rich in linear aliphatics. However, polypropylene (PP) pyrolysis typically yields branched olefins, potentially hindering effectiveness of HZSM-5 due to mass transfer constraints and coke blockage in micropores. This study modifies HZSM-5 through phosphorus impregnation, mesopore introduction, and steam treatment to evaluate the impact of acidity, pore size, and surface modifications on catalyst stability and light olefin selectivity during PP pyrolysis vapor cracking. Subsequent experiments reveal the superior stability of modified catalysts. Phosphorus-modified (P-HZSM-5ss) and mesoporous phosphorus-modified (P-mesoHZSM-5ss) catalysts retain 72 % and 80 % of their initial activity after 150 runs, respectively, while the parent HZSM-5 experiences a rapid 44 % activity loss. P-mesoHZSM-5ss demonstrates the highest light olefin selectivity (63 wt%) after 150 runs, attributed to improved accessibility of branched olefinic products to active sites within catalyst pores. Further optimization achieves exceptional light olefin selectivity of 84 wt% at 117 ms contact time and 550 °C, surpassing maximum selectivity of the parent catalyst. Comparative analyses of PP, PE, and mixed polyolefinic waste pyrolysis vapor cracking revealed the influence of polyolefin type on optimal operational conditions, stressing the need for flexibility in operating conditions to scale up the proposed polyolefin recycling method. This study highlights the potential of tailored catalyst modifications and process optimization to efficiently convert PP into valuable light olefins, advancing sustainable polyolefin recycling technologies.

Stereochemical Tailoring of Nickel‐based Electrocatalysts for Hydrogen Evolution Reaction

AbstractThe search for alternative non‐noble transition metal catalysts able to evolve hydrogen has been the focus of intense research. Molecular complexes bearing redox‐active ligands have been reported as efficient electrocatalysts for hydrogen evolution reaction (HER). This study showcases a new family of nickel‐thiosemicarbazone complexes displaying significant activity for HER in DMF solvent using trifluoracetic acid as proton source. Following previous works in our group, the ligand was stereochemically tailored, placing methoxy groups at different locations and considering various combinations of positions. Three complexes within the series were shown to outperform the parent catalyst bearing the methoxy group in para position. Overall, the nickel catalyst having the chemical substituent in meta position displays the best catalytic performances while having the lowest overpotential. These results support that ligand stereochemical tailoring in metal complexes improves electrocatalytic HER and suggest that ligand tuning is a promising direction to enhance catalyst performances.

Boron‐Induced Interstitial Effects Drive Water Oxidation on Ordered Ir‐B Compounds

Interstitial filling of light atoms strongly affects the electronic structure and adsorption properties of the parent catalyst due to ligand and ensemble effects. Different from the conventional doping and surface modification, constructing ordered intermetallic structures is more promising to overcome the dissolution and reconstruction of active sites through strong interactions generated by atomic periodic arrangement, achieving joint improvement in catalytic activity and stability. However, for tightly arranged metal lattices, such as iridium (Ir), obtaining ordered filling atoms and further unveiling their interstitial effects are still limited by highly activated processes. Herein, we report a high‐temperature molten salt assisted strategy to form the intermetallic Ir‐B compounds (IrB1.1) with ordered filling by light boron (B) atoms. The B residing in the interstitial lattice of Ir constitutes favorable adsorption surfaces through a donor‐acceptor architecture, which has an optimal free energy uphill in rate‐determining step (RDS) of oxygen evolution reaction (OER), resulting in enhanced activity. Meanwhile, the strong coupling of Ir‐B structural units suppresses the demetallation and reconstruction behavior of Ir, ensuring catalytic stability. Such B‐induced interstitial effects endow IrB1.1 with higher OER performance than commercial IrO2, which is further validated in proton exchange membrane water electrolyzers (PEMWEs).

Recent progress in defect-engineered metal oxides for photocatalytic environmental remediation.

Rapid industrial advancement over the last few decades has led to an alarming increase in pollution levels in the ecosystem. Among the primary pollutants, harmful organic dyes and pharmaceutical drugs are directly released by industries into the water bodies which serves as a major cause of environmental deterioration. This warns of a severe need to find some sustainable strategies to overcome these increasing levels of water pollution and eliminate the pollutants before being exposed to the environment. Photocatalysis is a well-established strategy in the field of pollutant degradation and various metal oxides have been proven to exhibit excellent physicochemical properties which makes them a potential candidate for environmental remediation. Further, with the aim of rapid industrialization of photocatalytic pollutant degradation technology, constant efforts have been made to increase the photocatalytic activity of various metal oxides. One such strategy is the introduction of defects into the lattice of the parent catalyst through doping or vacancy which plays a major role in enhancing the catalytic activity and achieving excellent degradation rates. This review provides a comprehensive analysis of defects and their role in altering the photocatalytic activity of the material. Various defect-rich metal oxides like binary oxides, perovskite oxides, and spinel oxides have been summarized for their application in pollutant degradation. Finally, a summary of existing research, followed by the existing challenges along with the potential countermeasures has been provided to pave a path for the future studies and industrialization of this promising field.

Top-down fabrication of active interface between TiO2 and Pt nanoclusters. Part 2: Catalytic performance and reaction mechanism in CO oxidation

In this work, following Part 1 that has found a redispersion process from Pt nanoparticles (NPs, about 3.4 nm) to nanoclusters (NCs, about 1 nm) on TiO2 and elucidated its mechanism, we carefully investigated the catalytic performance of the obtained Pt NC catalyst in CO oxidation as well as the corresponding reaction mechanism. The Pt NC catalyst excels than its parent catalyst in terms of both intrinsic and apparent activity. Detailed studies by combining kinetic measurements, isotopic labeling reaction experiments, and low-temperature operando FT-IR unambiguously demonstrated that the Pt NCs deposited on TiO2 can form unique interfacial sites that enable to active O2 at very low temperature, thus the CO adsorbed on TiO2 can diffuses to, and reacts with, the activated oxygen, rendering a high activity at low temperatures. This work is contributory in understanding the origin of the high activity of the supported metal cluster catalysts.

Alkaline-earth ion stabilized sub-nano-platinum tin clusters for propane dehydrogenation.

The strong promotion effects of alkali/alkaline earth metals are frequently reported for heterogeneous catalytic processes such as propane dehydrogenation (PDH), but their functioning principles remain elusive. This paper describes the effect of the addition of calcium (Ca) on reducing the deactivation rate of platinum-tin (Pt-Sn) catalyzed PDH from 0.04 h-1 to 0.0098 h-1 at 873 K under a WHSV of 16.5 h-1 of propane. The Pt-Sn-Ca catalyst shows a high propylene selectivity of >96% with a propylene production rate of 41 molC3H6 (gPt h)-1 and ∼1% activity loss after regeneration. The combination of characterization and DFT simulations reveals that Ca acts as a structural promoter favoring the transition of Snn+ in the parent catalyst to Sn0 during reduction, and the latter is an electron donor that increases the electron density of Pt. This greatly suppresses coke formation from deep dehydrogenation. Moreover, it was found that Ca promotes the formation of a highly reactive and sintering-resistant sub-nano Pt-Sn alloy with a diameter of approximately 0.8 nm. These lead to high activity and selectivity for the Pt-Sn-Ca catalyst for PDH.

Locking the Conformation of a Paddlewheel Rhodium Complex: Design, Synthesis, and Applications in Catalytic Nitrene Transfers

AbstractThe exponential proliferation of conformers makes it impossible to examine the entire population in most systems. Controlling conformational ensembles is thus pivotal in many areas of chemistry. Rh2(esp)2, a dicarboxylate‐derived paddlewheel rhodium complex, is one of the most effective catalysts for nitrene chemistry. Its enormous success has led to preparing many analogous complexes. However, there has been little consideration for the conformational dynamics of the parent catalyst. Herein, we report a new ligand modification principle that prevents conformer interconversion. The resulting complex comprises two isolable conformers, whose structures have been determined by X‐ray diffraction. Combined experimental and computational data has revealed similarities and dissimilarities between the conformationally confined and parent complexes. Three model cases have demonstrated the utility of conformational fixation in the development of stereoselective catalysts for nitrene transfer reactions. The design principle described in this study can be combined with other established modification strategies, serving as a springboard for further advancement of the chemistry of paddlewheel metal complexes.

Locking the Conformation of a Paddlewheel Rhodium Complex: Design, Synthesis, and Applications in Catalytic Nitrene Transfers.

The exponential proliferation of conformers makes it impossible to examine the entire population in most systems. Controlling conformational ensembles is thus pivotal in many areas of chemistry. Rh2(esp)2, a dicarboxylate-derived paddlewheel rhodium complex, is one of the most effective catalysts for nitrene chemistry. Its enormous success has led to preparing many analogous complexes. However, there has been little consideration for the conformational dynamics of the parent catalyst. Herein, we report a new ligand modification principle that prevents conformer interconversion. The resulting complex comprises two isolable conformers, whose structures have been determined by X-ray diffraction. Combined experimental and computational data has revealed similarities and dissimilarities between the conformationally confined and parent complexes. Three model cases have demonstrated the utility of conformational fixation in the development of stereoselective catalysts for nitrene transfer reactions. The design principle described in this study can be combined with other established modification strategies, serving as a springboard for further advancement of the chemistry of paddlewheel metal complexes.

Influence of pseudoboehmite properties on characteristics of CoMo/ASA-Al2O3 catalysts for selective hydrotreating of FCC gasoline

The influence of alumina precursor (pseudoboehmites) in CoMo/ASA + Al2O3 catalysts on catalytic activity in FCC gasoline hydrotreating has been studied. Pseudoboehmites prepared by alcoholate, precipitate and hydrothermal technologies were used. Parent powders, supports and catalysts were characterized by low-temperature N2 adsorption, TPD of ammonia, STEM, HRTEM, UV–vis spectroscopy. Catalysts were tested in hydrotreating of the model FCC gasoline feedstock. It is shown that the choice of pseudoboehmite has significant effect on textural, acid and mechanical properties of supports and catalysts, as well as dispersity of the active phase. The type of pseudoboehmite affects the amount of tetrahedral cobalt in catalysts that changes surface activity per 1 g of the catalyst. The linear dependence between the ratio of the medium and weak acid sites and catalyst selectivity was found. It is established that isomerizing activity is higher than the hydrogenating one, when medium/weak acid sites ratio in the catalyst is lower than 1.85.

Fabrication of an S-Scheme Heterojunction Photocatalyst MoS2/PANI with Greatly Enhanced Photocatalytic Performance.

As a promising catalyst, MoS2 has been widely studied owing to its high chemical reactivity, excellent electrical carrier mobility, good optical properties, and narrow band gap. However, the high recombination rate of photoinduced charge carriers limits its practical application in photocatalysis. In this study, MoS2 was coupled with PANI to fabricate an S-scheme heterojunction MoS2/PANI. The synthesized products were characterized systematically, and their photocatalytic properties were evaluated by photocatalytic degradation of norfloxacin (NOR) and rhodamine B (RhB). The obtained results indicated that the fabricated MoS2/PANI inorganic-organic heterojunction displayed tremendously enhanced photocatalytic activity. The degradation efficiencies for 60 mg L-1 of NOR and RhB are 86 and 100% under the simulated sunlight irradiation for 1 h with 10 mg of catalyst, which are 13 and 47 times higher than those of pure MoS2, respectively. Interestingly, it is superior to the previously reported related materials. The remarkably enhanced photocatalytic activity of MoS2 is assigned to the high charge conductivity feature of PANI and the formed S-scheme heterojunction that result in a steric separation of holes and electrons and conserve the initial powerful redox ability of the parent catalysts. This study provides a facile method to greatly improve the photocatalytic activity of MoS2 and facilitates its application for highly efficient removal of organic pollutants, such as antibiotic drugs and organic dyes, utilizing solar energy.

Structural and Reactivity Effects of Secondary Metal Doping into Iron-Nitrogen-Carbon Catalysts for Oxygen Electroreduction.

While improved activity was recently reported for bimetallic iron-metal-nitrogen-carbon (FeMNC) catalysts for the oxygen reduction reaction (ORR) in acid medium, the nature of active sites and interactions between the two metals are poorly understood. Here, FeSnNC and FeCoNC catalysts were structurally and catalytically compared to their parent FeNC and SnNC catalysts. While CO cryo-chemisorption revealed a twice lower site density of M-Nx sites for FeSnNC and FeCoNC relative to FeNC and SnNC, the mass activity of both bimetallic catalysts is 50-100% higher than that of FeNC due to a larger turnover frequency in the bimetallic catalysts. Electron microscopy and X-ray absorption spectroscopy identified the coexistence of Fe-Nx and Sn-Nx or Co-Nx sites, while no evidence was found for binuclear Fe-M-Nx sites. 57Fe Mössbauer spectroscopy revealed that the bimetallic catalysts feature a higher D1/D2 ratio of the spectral signatures assigned to two distinct Fe-Nx sites, relative to the FeNC parent catalyst. Thus, the addition of the secondary metal favored the formation of D1 sites, associated with the higher turnover frequency.

Enhancement of Catalytic Activity on Crude Palm Oil Hydrocracking over SiO2/Zr Assisted with Potassium Hydrogen Phthalate.

In this study, the catalytic activity of bifunctional SiO2/Zr catalysts prepared by template and chelate methods using potassium hydrogen phthalate (KHF) for crude palm oil (CPO) hydrocracking to biofuels was investigated. The parent catalyst was successfully prepared by the sol-gel method, followed by the impregnation of zirconium using ZrOCl2·8H2O as a precursor. The morphological, structural, and textural properties of the catalysts were examined using several techniques, including electron microscopy energy-dispersive X-ray with mapping, transmission electron microscopy, X-ray diffraction, particle size analyzer (PSA), N2 adsorption-desorption, Fourier transform infrared-pyridine, and total and surface acidity analysis using the gravimetric method. The results showed that the physicochemical properties of SiO2/Zr were affected by different preparation methods. The template method assisted by KHF (SiO2/Zr-KHF2 and SiO2-KHF catalysts) provides a porous structure and high catalyst acidity. The catalyst prepared by the chelate method assisted by KHF (SiO2/Zr-KHF1) exhibited excellent Zr dispersion toward the SiO2 surface. The modification remarkably enhanced the catalytic activity of the parent catalyst in the order SiO2/Zr-KHF2 > SiO2/Zr-KHF1 > SiO2/Zr > SiO2-KHF > SiO2, with sufficient CPO conversion. The modified catalysts also suppressed coke formation and resulted in a high liquid yield. The catalyst features of SiO2/Zr-KHF1 promoted high-selectivity biofuel toward biogasoline, whereas SiO2/Zr-KHF2 led to an increase in the selectivity toward biojet. Reusability studies showed that the prepared catalysts were adequately stable over three consecutive runs for CPO conversion. Overall, SiO2/Zr prepared by the template method assisted by KHF was chosen as the most prominent catalyst for CPO hydrocracking.

Recent Advances in the Study of In Situ Combustion for Enhanced Oil Recovery

Global estimates for our remaining capacity to exploit developed oil fields indicate that the currently recoverable oil (light oil) will last for approximately 50 years. This necessitates the development of viscous and superviscous oil fields, which will further compensate for the loss of easily produced oil. In situ combustion is the most promising production method, which allows for increased oil recovery from a reservoir. This being the case, this study provides an overview of global trends regarding the research and implementation of the method under consideration, in order to promote understanding of its applicability and effectiveness. The background to the development of the method is discussed in detail, illustrating the growing interest of researchers in its study. Cases of both successful as well as inefficient implementations of this method in real oil fields are considered. The main focus of the article is to investigate the influence of the parent rock and catalysts on the combustion process, as this is a new and actively developing area in the study of enhanced oil recovery using in situ combustion. Geological surveys, in addition to experimental and numerical studies, are considered to be the main methods that are used to investigate processes during in situ combustion. The analysis that we carried out led us to understand that the processes which occur during the combustion of heavy oil are practically unpredictable and, therefore, poorly understood. The specificity of the oil composition under consideration depends on the field, which can lead to a change in the required temperature regimes for its production. This indicates that there exists multiple specific applications for the method under consideration, each requiring additional full studies into both the fractional composition of oil and its reservoirs. The article also considers various technologies for implementing the in situ combustion method, such as ND-ISC, THAITM, COSH, CAGD, and SAGD. However, the literature review has shown that none of the technologies presented is widely used, due to the lack of an evidence base for their successful application in the field. Moreover, it should be noted that this method has no limits associated with the oil occurrence depth. This technology can be implemented in thin reservoirs, as well as in flooded, clayey, sandy, and carbonate reservoirs. The review we have presented can be considered as a guide for further research into the development of global solutions for using the proposed method.

The role of aluminum in Sn-Al-beta zeolite catalyzing the conversion of glucose to methyl lactate

The preparation of H-Beta zeolites with different Si/Al ratios (Si/Al=14, Si/Al=288) was obtained by desiliconization and dealumination. Subsequently, Sn-Al-Beta catalysts were prepared by tin grafting and used for the conversion of glucose to methyl lactate. The results indicate that the yield of methyl lactate from the catalyst obtained using the parent H-beta synthesis with a high Si/Al ratio is higher than that of methyl lactate from the parent catalyst with a low initial Si/Al ratio. And the maximum methyl lactate yield of 46.66% was achieved on Sn-Al-Beta (DSi-277). In contrast, the yield of methyl lactate on Sn-Al-Beta (DAl-493) was 24.54%. Results from spectroscopic analysis and probe molecular FTIR indicated that the post-synthesis process altered the structure of the zeolite, which changed its aluminum concentration and existence form (1.8ppm chemical shift), Additionally, when the aluminum interacted with the Sn that had been added to the zeolite, it encouraged the Sn transformation to the high energy state and created the weaker Lewis acid site, as well as more effective action to improve reaction yield.

Selective Production of Gasoline Fuel Blendstock from Methanol using a Metal-doped HZSM-5 Zeolite Catalyst

The increasing demand for substitutes for petroleum has become a global concern due to the looming petroleum crisis and the need to reduce carbon dioxide emissions. This study seeks a viable approach for converting methanol into petrochemicals and fuel-range hydrocarbons. A ZSM-5 zeolite catalyst was synthesised and modified with 0.5 wt% transition metals (Co and Ni) to improve selectivity towards the desired liquid product (gasoline) in the methanol-to-hydrocarbon (MTH) conversion. The synthesised catalyst was characterised using various techniques. The catalysts were further evaluated for methanol conversion into fuels and petrochemicals (BTX) under varying weight hourly space velocity (WHSV) (7 and 12 h-1) at 350 oC. Results showed that the synthesised catalyst exhibited characteristic features of a typical MFI framework of a zeolite catalyst. The catalyst evaluation results revealed that changes in operating conditions affected product distribution. A WHSV of 12 h-¹ favoured the production of gasoline range hydrocarbons (C5-C12) with a yield of over 80 % for all catalysts. In addition, C12+ hydrocarbons were produced with a selectivity of 12.6 %, 0.7 % and 7.5 % for Ni-doped, Co-doped and HZSM-5 catalysts, respectively. In particular, the Co-doped catalyst showed a 7.1 % higher BTX yield under these specific operating conditions (12 h-1 and 350 oC). Compared to 7 h-1, increasing the WHSV to 12 h-1 favoured the production of liquid hydrocarbons. Incorporating a small amount of transition metal into the parent catalyst improved the selectivity of the target products and overall liquid hydrocarbon yield. The results concluded that the synthesised catalyst is promising for the MTH process, and catalytic performance can be enhanced by metal modification and optimising reaction conditions to improve biofuel production.

Catalytic pyrolysis of enzymatic hydrolysis lignin by transition-metal modified HZSM-5/MCM-41 core–shell catalyst for the enhancement of monocyclic aromatic hydrocarbons

Enzymatic hydrolysis lignin (EHL) is produced in large quantities during the fermentation of lignocellulosic biomass to produce ethanol, resulting in environmental pollution and resource waste. HZSM-5/MCM-41 core–shell zeolites (H/M) loaded with transition metal Mn, Fe, Co, Ni, Cu, and Zn at different loading levels (2, 4, 6, 8, and 10 wt%) were prepared as catalysts. Py-GC/MS was employed to investigate their effects on the selectivity for and relative abundance of monocyclic aromatic hydrocarbons (MAHs) in the catalytic pyrolysis products of EHL. On this basis, bimetal-loaded H/M catalysts were constructed, namely Fe-Zn@H/M, Fe-Co@H/M, Fe-Ni@H/M, Co-Zn@H/M, Co-Ni@H/M, and Zn-Ni@H/M. Co-Ni@H/M increased the selectivity for and relative abundance of MAHs by 11.68% and 28.01%, respectively, compared with the H/M catalyst. Moreover, Co-Ni@H/M induced a further increase in the selectivity for and abundance of MAHs compared with the corresponding monometal-loaded catalysts. The characterization results indicated that bimetallic Co and Ni loading were uniformly dispersed on the catalyst surface and did not change the structure of the parent catalyst but affected the pore characteristics and acidic site distribution of the catalyst. Further analysis of the pyrolysis products suggested that bimetallic Co and Ni loading enhanced the dealkylation capacity of the catalyst for furans, aldehydes and phenol derivatives. Oligomerization, cyclization and aromatization of short alkyl chains were promoted in the MAHs by Co-Ni@H/M. Meanwhile, bimetallic Co and Ni loading inhibited the polymerization of phenols and other oxygen-containing compounds by promoting dehydration, decarboxylation and decarbonylation, which indirectly reduced the formation of coke.