Dry Reforming Research Articles

Spontaneous regeneration of active sites against catalyst deactivation

Catalyst deactivation is one of the long-standing challenges in heterogeneous catalysis. Here, we found that the Ni/MgAl2O4 catalyst shows an atmosphere-dependent deactivation behavior during dry reforming of methane (DRM) process, i.e., oxidation and redispersion of Ni near the inlet in an oxidizing atmosphere while coking and sintering of Ni near the outlet in a reducing atmosphere. These structural evolutions of the Ni species are revealed to be driven by the surface oxidation degree of the catalyst, such that it is reversible when the redox atmosphere changes. It inspired us to develop an alternating-feeding gas strategy that periodically changes the gas flow direction to balance the structural evolution of Ni species across catalyst bed through the spontaneous regeneration of deactivated sites, enabling a supra-stable DRM process. This study provides new insights into the catalyst deactivation for DRM process, while opens a new avenue to address catalyst deactivation in various redox-catalyzed processes.

Soccer Ball‐like Assembly of Edge‐to‐edge Oriented 2D‐silica Nanosheets: A Promising Catalyst Support for High‐Temperature Reforming

AbstractControlled assembly of nanoparticles into well‐defined assembled architectures through precise manipulation of spatial arrangement and interactions allows the development of advanced mesoscale materials with tailored structures, hierarchical functionalities, and enhanced properties. Despite remarkable advancements, the controlled assembly of highly anisotropic 2Dnanosheets is significantly challenging, primarily due to the limited availability of selective edge‐to‐edge connectivity compared to the abundant large faces. Innovative strategies are needed to unlock the full potential of 2D‐nanomaterialsin self‐assembled structures with distinct and desirable properties. This research unveils the discovery of controlled self‐assembly of 2D‐silica nanosheets (2D‐SiNSs) into hollow micron‐sized soccer ball‐like shells (SA‐SiMS). The assembly is driven by the physical flexibility of the 2D‐SiNSs and the differential electricdouble‐layer charge gradient creating electrostatic bias on the edge and face regions. The resulting SA‐SiMS structures exhibit high mechanical stability, even at high‐temperatures, and exhibit excellent performance as catalyst support in the dry reforming of methane. The SA‐SiMS structures facilitate improved mass transport, leading to enhanced reaction rates, while the thin silica shell prevents sintering of small catalyst nanocrystals, thereby preventing coke formation. This discovery sheds light on the controllable self‐assembly of 2D nanomaterials and provides insights into the design and synthesis of advanced mesoscale materials with tailored properties.

Soccer Ball-like Assembly of Edge-to-edge Oriented 2D-silica Nanosheets: A Promising Catalyst Support for High-Temperature Reforming.

Controlled assembly of nanoparticles into well-defined assembled architectures through precise manipulation of spatial arrangement and interactions allows the development of advanced mesoscale materials with tailored structures, hierarchical functionalities, and enhanced properties. Despite remarkable advancements, the controlled assembly of highly anisotropic 2Dnanosheets is significantly challenging, primarily due to the limited availability of selective edge-to-edge connectivity compared to the abundant large faces. Innovative strategies are needed to unlock the full potential of 2D-nanomaterialsin self-assembled structures with distinct and desirable properties. This research unveils the discovery of controlled self-assembly of 2D-silica nanosheets (2D-SiNSs) into hollow micron-sized soccer ball-like shells (SA-SiMS). The assembly is driven by the physical flexibility of the 2D-SiNSs and the differential electricdouble-layer charge gradient creating electrostatic bias on the edge and face regions. The resulting SA-SiMS structures exhibit high mechanical stability, even at high-temperatures, and exhibit excellent performance as catalyst support in the dry reforming of methane. The SA-SiMS structures facilitate improved mass transport, leading to enhanced reaction rates, while the thin silica shell prevents sintering of small catalyst nanocrystals, thereby preventing coke formation. This discovery sheds light on the controllable self-assembly of 2D nanomaterials and provides insights into the design and synthesis of advanced mesoscale materials with tailored properties.

Cs promoted Ni/ZrO2-Al2O3 catalysts for dry reforming of methane: Promotional effects of Cs for enhanced catalytic activity and stability

Carbon Capture and Utilization (CCU) technologies offer a promising avenue for transforming captured CO2 into valuable products, serving as renewable fuels or precursors for high-value synthesis. This study explores the dry reforming of methane (DRM) as a viable pathway to convert captured CO2 and CH4 into syngas, achieving high equilibrium conversion through the use of suitable catalysts. Conventional nickel-based catalysts are susceptible to carbon deposition, necessitating innovative approaches to enhance their performance. A tubular microreactor was employed to conduct the reforming process at 800 °C, utilizing Cs-promoted Ni catalysts supported on 90 % Al2O3 and 10 % ZrO2-based support composition. Catalyst preparation involved the impregnation technique, and subsequent characterization employed N2-physisorption, XRD, H2-TPR, TGA, TPD, and Raman spectroscopy. The DRM reaction was systematically investigated using the Ni/ ZrO2- Al2O3 catalysts, with a specific focus on the catalytic effects of Cs promotion. Observations revealed that Cs incorporation onto the ZrO2- Al2O3 matrix led to a substantial increase in hydrogen yield and selectivity across all catalyst compositions, accompanied by a significant reduction in carbon deposition on the catalyst surface. The optimal Cs loading, determined to be 3 wt% over Ni/ ZrO2- Al2O3 catalyst, exhibited CO2 and CH4 conversions of 90 % and 87 %, respectively, with an H2/CO yield approaching 1 (0.95). This research underscores the potential of Cs-modified catalysts in enhancing the efficiency of DRM for CCU applications, providing valuable insights into optimizing catalyst formulations for improved performance in carbon transformation processes.

La2O3-CeO2-Supported Bimetallic Cu-Ni DRM Catalysts.

The present work is focused on nickel catalysts supported on La2O3-CeO2 binary oxides without and with the addition of Cu to the active component for the dry reforming of methane (DRM). The catalysts are characterized using XRD, XRF, TPD-CO2, TPR-H2, and low-temperature N2 adsorption-desorption methods. This work shows the effect of different La:Ce ratios (1:1 and 9:1) and the Cu addition on the structural, acid base, and catalytic properties of Ni-containing systems. The binary LaCeOx oxide at a ratio of La:Ce = 1:1 is characterized by the formation of a solid solution with a fluorite structure, which is preserved upon the introduction of mono- or bimetallic particles. At La:Ce = 9:1, La2O3 segregation from the solid solution structure is observed, and the La excess determines the nature of the precursor of the active component, i.e., lanthanum nickelate. The catalysts based on LaCeOx (1:1) are prone to carbonization during 6 h spent on-stream with the formation of carbon nanotubes. The Cu addition facilitates the reduction of the Cu-Ni catalyst carbonization and increases the number of structural defects in the carbon deposition products. The lanthanum-enriched LaCeOx (9:1) support prevents the accumulation of carbon deposition products on the surface of CuNi/La2O3-CeO2 9:1, providing high DRM activity and an H2/CO ratio of 0.9.

SYNGAS PRODUCTION BY DRY REFORMING AND BI-REFORMING OF METHANE OVER SOL-GEL MADE Со-Rh/AL2O3 BIMETALLIC CATALYSTS

The most important global challenge of concern for humanity is the change in the Earth's climate due to greenhouse gas (GHG) emissions. In this regard, carbon dioxide reforming of methane is once again attracting more attention as the process uses two major greenhouse gases - methane (CH4) and carbon dioxide (CO2) as feedstock. The reaction product of which is synthesis gas, which is the primary building block to produce various valuable products. Rapid catalyst deactivation due to coking makes industrial development of this process difficult. Additionally, the low H2/CO ratio in synthesis gas, usually below 1.0, limits its further utilization. To solve these issues, it is necessary to create new effective coking-resistant catalysts, improve their chemical and structural composition and preparation methods, and optimize the process conditions. In this work, 5%Co-Rh/Al2O3, a bimetallic catalyst prepared by the sol-gel method (modified Pechini method) was studied in the processes of carbon dioxide and combined steam-carbon dioxide reforming of methane. It was shown that 5%Co-Rh(98:2)/Al2O3 sol-gel catalyst had a high activity in the carbon dioxide reforming of methane. The introduction of steam into the initial CH4-CO2 feedstock allows the regulation of the composition of the produced synthesis gas depending on the amount of water. At t=8000 , the degree of methane conversion is 92.5-95.8%, carbon dioxide – 85.6-97.4%, and H2/CO ratio = 1.0-2.1 depending on the amount of steam added.

Dry Reforming of Methane over Li-Doped Ni/TiO2 Catalysts: Effect of Support Basicity

In this research, we investigate the impact of Li doping on a TiO2 support, synthesized through the sol-gel method, with a focus on varying the aging time. Our objective is to elucidate how aging duration and doping influence the surface basicity, thereby mitigating carbon formation and amplifying the catalytic efficacy of Ni-loaded catalysts (15 wt.%). Essential characterization techniques encompass X-ray diffraction, H2-TPR, FE-SEM, N2-physisorption, DLS, FTIR, and Raman spectroscopies. Our findings reveal that extended aging periods promote the development of a basic character, attributable to oxygen defects within TiO2. This inherent trait bears significant implications for catalyst performance, stability, and carbon formation during the reaction. Remarkably, the catalyst with the highest catalytic activity and stability boasts an 85% relative basicity, a property also induced by incorporating lithium into the TiO2 support.

Life cycle environmental performance of methanol production through photocatalytic dry methane reforming

Photocatalytic dry methane reforming uses light energy and a nanostructured photocatalyst to convert both carbon dioxide and methane gas to syngas for production of fuels and value-added chemicals. The conversion of these two greenhouse gases (GHG) makes photocatalytic dry methane reforming a potentially environmentally attractive process; however, little research has been done to assess its life cycle environmental impacts in comparison to conventional commodity chemical production methods. Further, practical research has been limited to lab scale studies, which do not fully reflect the technical and environmental performance of commercial scale systems. In this work, a simulation describing the production of methanol from a photocatalytic dry reforming process is used to inform a life cycle assessment to estimate its potential environmental impacts at scale. Results indicate that for methanol produced via photocatalytic dry methane reforming to have the same life cycle GHG intensity as methanol produced through conventional steam methane reforming, a combination of improved technological performance and process intensification is required. This includes increased chemical conversion, electricity grid decarbonization, and the use of low greenhouse gas intensive feedstocks. Promisingly, results indicate that methanol produced using a photocatalytic dry methane reforming process that employs landfill gas as a feedstock and 100% renewable electricity, could potentially produce methanol with a negative global warming potential. Opportunities to improve the environmental impact of a photocatalytic dry reforming process so as to widen its scenario applicability are also discussed.

Plasma-based dry reforming of CH4: Plasma effects vs. thermal conversion

In this work we evaluate the chemical kinetics of dry reforming of methane in warm plasmas (1000–4000 K) using modelling with a newly developed chemistry set, for a broad range of parameters (temperature, power density and CO2/CH4 ratio). We compare the model against thermodynamic equilibrium concentrations, serving as validation of the thermal chemical kinetics. Our model reveals that plasma-specific reactions (i.e., electron impact collisions) accelerate the kinetics compared to thermal conversion, rather than altering the overall kinetics pathways and intermediate products, for gas temperatures below 2000 K. For higher temperatures, the kinetics are dominated by heavy species collisions and are strictly thermal, with negligible influence of the electrons and ions on the overall kinetics. When studying the effects of different gas mixtures on the kinetics, we identify important intermediate species, side reactions and side products. The use of excess CO2 leads to H2O formation, at the expense of H2 formation, and the CO2 conversion itself is limited, only approaching full conversion near 4000 K. In contrast, full conversion of both reactants is only kinetically limited for mixtures with excess CH4, which also gives rise to the formation of C2H2, alongside syngas. Within the given parameter space, our model predicts the 30/70 ratio of CO2/CH4 to be the most optimal for syngas formation with a H2/CO ratio of 2.

Thermodynamic performance comparison of a SOFC system integrated with steam reforming and dry reforming by utilizing different fuels

This work investigates the thermodynamic analysis of syngas production from several fuels by steam reforming or dry reforming for SOFC-integrated systems. Four commonly used fuels are considered: methanol and glycerol (alcohols), methane, and diesel (hydrocarbons). The integrated system is modeled on Aspen Plus using the Gibbs free energy minimization method and a generic electrochemical model to assess the effect of critical parameters on system performance. The results indicate a carbon-free zone within the reformer, and alcohols provide better resistance to carbon deposition than hydrocarbon fuels. Elevating the reforming temperature and STCR/CTCR increases the hydrogen concentration of syngas while also avoiding carbon deposits in the external reformer. Increasing the temperature and fuel utilization factor of SOFCs has been found to enhance electrical efficiency but at the expense of diminished thermal and total efficiency. For given operating conditions, the electrical efficiencies of methanol, glycerol, methane, and diesel are observed to be 47%, 46%, 51%, and 49% for the SR-SOFC system, and 45%, 42%, 42%, and 33% for the DR-SOFC system, respectively. The methane-SR-SOFC and methanol-DR-SOFC systems have the highest electrical efficiency, while diesel is unsuitable for the DR-SOFC system. This work can advise engineers to select the appropriate fuel types and reform technologies for SOFC-integrated systems.

A mechanistic analysis of particle flow in a pulsatile circulating dual fluidized bed for chemical looping technology based on CDF-DEM simulation

This paper presents a three-dimensional computational fluid dynamic–discrete element method (CFD-DEM) model using Geldart class D particles for studying the fluid flow pattern in a circulating dual fluidized bed (CDFB) for chemical looping dry reforming of methane (CLDRM). The system design comprised a high-velocity air reactor (AR) also known as riser fluidized bed, a riser tube, a cyclone chamber, a fluidizing bed fuel reactor (FR), and a connecting loop, which closes the loop between AR and FR. The particles distribution, volume fraction, flow pattern, velocity and their circulation between the AR (riser) and FR (second fluidized bed) in CDFB were deeply investigated. The results showed that the CLDRM system experiences a pressure imbalance between the reduction and oxidation zones, causing solid particles to undergo a highly intricate and turbulent pulse flow. As a result, the operation of the system is alternately governed by two flow regimes: bubbling fluidization and pulsatile circulating fluidization. The burst of a high pressure pulses provide the pressure head required for circulation of the particles. The pulses also led to the intermittent transportation of particles ― in the form of particles clusters ― from high-pressure area to the region with a lower pressure.

Surface Basic Site Effect on Boron-Promoted Platinum Catalysts for Dry Reforming of Methane

Surface Basic Site Effect on Boron-Promoted Platinum Catalysts for Dry Reforming of Methane

Catalytic Dry-reforming of Methane Process with Co,Ni,Pd/Ca-La-O Mixed Oxides

A surfactant-assisted co-precipitation method was used to prepare the catalysts Co,Ni,Pd/CaO, Co,Ni,Pd/Ca0.97La3+0.03O, Co,Ni,Pd/Ca0.93La3+0.07O, and Co,Ni,Pd/Ca0.85La3+0.15O (1% each of Co, Ni, and Pd). La2O3 doping effect on the activity and stability of Co,Ni,Pd/CaO catalysts was investigated in dry reforming of methane. Catalysts were characterized by several techniques (X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), X-ray Fluorescence (XRF), Fourier Transform Infra Red (FTIR), Temperature Programmed Desorption H2 (H2-TPR), Transmission electron microscopes (TEM), and Temperature Gravimetric Analysis (TGA)) and were tested in a fixed-bed reactor at 900 °C and (Gas Hourly Specific Velocity (GHSV) = 15000 mL.gcat−1.h−1, atmospheric pressure). Adding La2O3 had little effect on the morphology of the Co,Ni,Pd/CaO catalyst. However, it played a crucial role in enhancing the catalyst’s reducibility and CO2 adsorption at high temperatures, as indicated by the activity and stability of the Co,Ni,Pd/CaO catalyst. The carbon deposition on utilized catalysts after 5 hours at 900 °C was examined using TEM and thermal gravimetric analysis (TGA) techniques. Compared to Co,Ni,Pd/CaO catalysts across the entire temperature range, the tri-metallic Co,Ni,Pd/Ca0.85La3+0.15O catalyst with a lanthanum promoter demonstrated a greater conversion of CH4 (84%) and CO2 (92 %) at a 1:1 CH4:CO2 ratio. The selectivity of H2/CO reduced in the following order: Co,Ni,Pd/Ca0.85La3+0.15O > Co,Ni,Pd/Ca0.93La3+0.07O > Co,Ni,Pd/Ca0.97La3+0.03O > Co,Ni,Pd/CaO. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

CO2 Impact on Methane Pyrolysis as a Key Issue of Using Biogas as an Educt: A Theoretical Study

Dry reforming of methane (DRM) has attracted great interest for the production of syngas and/or hydrogen in a more environmentally friendly way. It is especially advantageous in this case to use biogas—as a mixture of methane, CO2, and traces of further gases—as a feedstock replacement for natural gas. Nevertheless, industrial implementation of DRM is currently limited because of its inherent process restrictions. The biggest challenge of dry reforming is the deposition of carbon on the catalyst, known as “coking.” The focus of this theoretical study is to evaluate the feasibility of a biogas dry reforming process in a liquid metal (Sn) bubble column reactor. This technology has already been proven suitable for methane pyrolysis to obtain hydrogen, preventing issues related to reactor clogging or catalyst deactivation caused by carbon deposition. Results show that at high operating temperatures and atmospheric pressure, a product gas primarily composed of H2 and CO would be obtained. CO2 and water vapor may also be present in the final product depending on the operating conditions. The molten tin inside the reactor would, according to the presented theoretical considerations, not be affected by the formation of carbides and oxides. Additionally, the syngas composition (the H2 : CO ratio) could be adjusted by using different CH4 : CO2 feed ratios.

Facile synthesis of an Ni/LaAlO3 – Perovskite via an MOF gel precursor for the dry reforming of methane

A simple strategy to prepare the pure perovskite phase of lanthanum aluminate (LaAlO3) by calcination of a highly porous, dry MOF precursor gel has been developed. This study demonstrates that the structural and textural properties, such as specific surface area, pore volumes and pore sizes, of precursor-like metal–organic gels (MOG) (MOG-Al-La) based on metal–organic framework (MOF) structures can be modulated by optimizing the solvothermal treatment time. The perovskite obtained after solvothermal treatment at 120 °C for 12 h and calcination at 750 °C maintained the mesoporous characteristics of the MOF precursor, with a small particle size due to the decrease in crystallization temperature. These properties in the support allowed a good dispersion of the active Ni sites, low reducibility, and a strong interaction between them and the support, thus suppressing sintering under the severe catalytic reaction conditions evaluated (GHSV = 120,000 cm3/g·h) for the dry reforming of methane. The resulting MOX-(12 h)-LaAlO3-750-Ni catalyst gave a CH4 average conversion of 75% and CO2 average conversion of 80% after 20 h of reaction. The improved stability of the catalyst was attributed to suppression of the formation of the dense network of carbon filaments that can stress and subsequently fracture the support, cause attrition of the catalyst granules and hinder diffusion of the reactants both through the pores of the support and the interparticle spaces.

A DFT study of elementary reaction steps of dry reforming of methane catalyzed by Ni: Explaining the difference between Ni particles supported on CeO2 and MnO[formula omitted]-doped CeO2

With the aid of DFT calculations, we investigate the elementary reaction steps of dry reforming of methane (DRM) on Ni(111) and NiO(100) as simple models of metallic and oxidized Ni catalysts. The reaction-path calculations reveal that DRM is feasible on metallic Ni at elevated temperatures. However, a notable problem with metallic Ni catalysts is the coke formation because the activation barrier for the C* formation is not considerably higher than those of the competing reactions that lead to the DRM products. In contrast, NiO does not encounter issues with coke formation, but it is not an effective catalyst due to too high activation energies and slow surface diffusion of H*. We also explain the experimentally observed difference between the DRM catalysts consisting of Ni particles supported on undoped and MnOx-doped CeO2 supports (designated as Ni/CeO2 and Ni/MnxCeO2, respectively). Specifically, we explain the absence of the 2020 cm−1 vibrational peak on the Ni/MnxCeO2 catalyst. Calculations univocally attribute the experimentally observed 2020 cm−1 peak to CO adsorbed on a top site of metallic Ni because all other sites and involved species display considerably different frequencies. The CO stretching frequency increases as Ni oxidizes, and on NiO(100), it is similar to the vibration of CO on the CeO2(111) support, about 2100 cm−1. Current results thus provide a sound explanation of why Ni/MnxCeO2 is a superior DRM catalyst to Ni/CeO2. In particular, the presence of the 2020 cm−1 peak on the Ni/CeO2 catalyst signals that Ni particles are sufficiently metallic and thus susceptible to carbon poisoning. In contrast, the absence of the 2020 cm−1 peak on the Ni/MnxCeO2 catalyst indicates that Ni particles are oxidized, i.e., the Ni oxidation is low enough to allow the DRM reaction but high enough to reduce the catalyst’s carbon poisoning.

Enhanced Stability of Iridium Nanocatalysts via Exsolution for the CO2 Reforming of Methane.

The reforming reactions of greenhouse gases require catalysts with high reactivity, coking resistance, and structural stability for efficient and durable use. Among the possible strategies, exsolution has been shown to demonstrate the requirements needed to produce appropriate catalysts for the dry reforming of methane, the conversion of which strongly depends on the choice of active species, its interaction with the support, and the catalyst size and dispersion properties. Here, we exploit the exsolution approach, known to produce stable and highly active nanoparticle-supported catalysts, to develop iridium-nanoparticle-decorated perovskites and apply them as catalysts for the dry reforming of methane. By studying the effect of several parameters, we tune the degree of exsolution, and consequently the catalytic activity, thereby identifying the most efficient sample, 0.5 atomic % Ir-BaTiO3, which showed 82% and 86% conversion of CO2 and CH4, respectively. By comparison with standard impregnated catalysts (e.g., Ir/Al2O3), we benchmark the activity and stability of our exsolved systems. We find almost identical conversion and syngas rates of formation but observe no carbon deposition for the exsolved samples after catalytic testing; such deposition was significant for the traditionally prepared impregnated Ir/Al2O3, with almost 30 mgC/gsample measured, compared to 0 mgC/gsample detected for the exsolved system. These findings highlight the possibility of achieving in a single step the mutual interaction of the parameters enhancing the catalytic efficiency, leading to a promising pathway for the design of catalysts for reforming reactions.

Kinetic Analysis of Dry Reforming of Methane on Traditional and Membrane Catalysts

Kinetic Analysis of Dry Reforming of Methane on Traditional and Membrane Catalysts

Syngas production via dry reforming of methane over Ni/MgO-ZrO2 catalyst

This study intended to evaluate the catalytic activity of Ni/MgO-ZrO2 to produce syngas through dry reforming of methane (DRM). The catalyst was prepared by using co-precipitation method followed by impregnation of Ni metal. XRD, BET and FESEM were used to analyze the physicochemical characteristics of the prepared catalyst. A stainless steel vertical reactor fixed with a catalyst bed inside was used to run the DRM process at 800°C, 1 atm and 1:1:1 ratio of CO2:CH4:N2. From the three catalysts studied, Ni/MgO-15%ZrO2 had the maximum conversion for CH4 and CO2 compared to the other two catalysts. The high conversion achieved was because of zirconium oxide. The result obtained from the DRM reaction was further supported by the characterization results, which included average particle size, the morphology of the catalyst, and catalyst peaks.

Catalytic evaluation of Pd-promoted Ni-Co/Al2O3 catalyst for glycerol dry reforming: Assessing hydrogen-rich syngas production, kinetics and mechanisms

The Pd-promoted Ni-Co bimetallic catalysts were prepared using ultrasonic-assisted impregnation, and their performance was subsequently assessed in a fixed-bed reactor. The catalyst's performance was evaluated in glycerol dry reforming (GDR) over a range of temperatures, from 873 K to 1173 K and reactant partial pressures ranging from 10 kPa to 40 kPa. The results indicated that as the temperature was raised from 873 K to 1073 K, there was a noticeable rise in both reactant conversion and product yield. However, beyond 1173 K, catalytic performance declined due to glycerol thermal cracking and sintering of the support at high temperatures, resulting in increased carbon formation. The presence of excessive CO2 was found to suppress glycerol adsorption on the catalyst surface, causing a decline in catalytic activity with a CO2 partial pressure of more than 20 kPa, regardless of reaction temperature. Additionally, excess CO2 were found to enhance the side reaction, particularly reverse water-gas shift (RWGS) that related to produce intermediate H2O. Similarly, the glycerol partial pressure was found to impact catalytic performance, with a decrease in performance beyond 20 kPa due to competing reactants between glycerol and CO2. According to the Langmuir-Hinshelwood kinetic mechanism, a dual molecular adsorption site for glycerol and CO2 was appropriate for this GDR reaction, with an associated activation energy of 47.3 kJ mol−1. The GDR reaction was identified as a kinetically controlled process due to its high activation energy, more than 25 kJ mol−1. The plausible mechanism of GDR over Pd-Ni-Co/Al2O3 occurred through the dissociative-type of adsorption of on active metallic sites of the catalysts for both reactant (glycerol and CO2). This was further facilitated by the bifunctional mechanisms based on H2 generated from dissociative adsorption involving both catalyst's basic sites and metallic active sites. This was ascribed to the highly dispersed and strong interaction between metal-support in Pd-promoted Ni-Co bimetallic catalysts.