Strong Metal-support Interaction Research Articles

Supported Inverse MnOx/Pt Catalysts Facilitate Reverse Water Gas Shift Reaction

Catalytic conversion of CO2 to CO via the reverse water gas shift (RWGS) reaction has been identified as a promising approach for CO2 utilization and mitigation of CO2 emissions. Bare Pt shows low activity for the RWGS reaction due to its low oxophilicity, with few research works having concentrated on the inverse metal oxide/Pt catalyst for the RWGS reaction. In this work, MnOx was deposited on the Pt surface over a SiO2 support to prepare the MnOx/Pt inverse catalyst via a co-impregnation method. Addition of 0.5 wt% Mn to 1 wt% Pt/SiO2 improved the intrinsic reaction rate and turnover frequency at 400 °C by two and twelve times, respectively. Characterizations indicate that MnOx partially encapsulates the surface of the Pt particles and the coverage increases with increasing Mn content, which resembles the concept of strong metal–support interaction (SMSI). Although the surface accessible Pt sites are reduced, new MnOx/Pt interfacial perimeter sites are created, which provide both hydrogenation and C-O activation functionalities synergistically due to the close proximity between Pt and MnOx at the interface, and therefore improve the activity. Moreover, the stability is also significantly improved due to the coverage of Pt by MnOx. This work demonstrates a simple method to tune the oxide/metal interfacial sites of inverse Pt-based catalyst for the RWGS reaction.

In suit decorating PdPt bimetals on titanium dioxide nanosheets for detecting ppb level of carbon monoxide and hydrogen

The catalyst with strong metal-support interactions often exhibits high catalytic activity. This study aims to prepare sensitive materials with strong metal-MOS interactions and explore their sensitization mechanism. Sn-PdPt/TiO2 was obtained by in-situ decorating PdPt bimetals on the surface of TiO2 NSs using Sn2+ as the reducing agent, and PdPt/TiO2 was prepared by traditional reduction method. Compared with TiO2 sensor, PdPt/TiO2 and Sn-PdPt/TiO2 sensors exhibited higher sensitivity, selectivity, lower operating temperature (200 °C) and detection limit (ppb level) to CO and H2. The sensitization of PdPt bimetal to TiO2 should be ascribed to the high catalytic activity of PdPt bimetal towards O2, H2 and CO, Schottky barrier at the interface between TiO2 and PdPt NPs, and the multiple valence states (Pd0, Pd2+ and Pd4+) of Pd will undergo mutual transformation during gas sensing reactions. And Sn-PdPt/TiO2 sensor exhibited higher sensitivity, selectivity and better stability than those of PdPt/TiO2 sensor, which can be attributed to the introduction of SnO2 and the stronger interaction between PdPt and TiO2 due to the in-situ reduction reaction. This study can provide some reference for preparing the MOS based gas sensing materials with strong metal-support interactions and understanding the sensitization mechanism of PdPt bimetal.

Enhanced coke resistant Ni/SiO2@SiO2 core–shell nanostructured catalysts for dry reforming of methane: Effect of metal-support interaction and SiO2 shell

Suppressing coke formation on nickel-based catalysts used in methane-dry reforming is one of the most important issues. We investigate the effect of nickel metal-support interaction and outer porous silica shells on the coke formation in methane dry reforming over Ni/SiO2@SiO2 core–shell catalysts. Using a simple ammonia evaporation method, the Ni/SiO2_AE catalyst, which has highly dispersed nickel nanoparticles with ca. 7 nm, was synthesized and coated with an outer porous silica shell to produce a Ni/SiO2_AE/SiO2 core shell catalyst. Based on the TEM and N2 isotherm results, a 20 nm thick SiO2 shell having pores with a size of about 2 nm was uniformly coated on the Ni/SiO2_AE catalyst. H2-TPR, and XPS analysis results suggest that the Ni/SiO2_AE and Ni/SiO2_AE@SiO2 catalysts have high nickel dispersion. This high dispersion is due to strong metal-support interactions and the formation of Ni phyllosilicate species. On the other hand, the ones synthesized by wet impregnation method have low nickel dispersion due to weaker metal-support interactions. The Ni/SiO2_AE@SiO2 core–shell catalyst showed stable catalytic activity under methane dry reforming conditions at 600 °C. On the other hand, the Ni/SiO2_WI and Ni/SiO2_AE catalysts showed rapid deactivation due to severe coke formation. It can be concluded that the strong metal-support interaction and the silica shell can suppress catalyst deactivation caused by coke formation very effectively.

Tuning Adsorbate-Mediated Strong Metal-Support Interaction by Oxygen Vacancy: A Case Study in Ru/TiO2.

The adsorbate-mediated strong metal-support interaction (A-SMSI) offers a reversible means of altering the selectivity of supported metal catalysts, thereby providing a powerful tool for facile modulation of catalytic performance. However, the fundamental understanding of A-SMSI remains inadequate and methods for tuning A-SMSI are still in their nascent stages, impeding its stabilization under reaction conditions. Here, we report that the initial concentration of oxygen vacancy in oxide supports plays a key role in tuning the A-SMSI between Ru nanoparticles and defected titania (TiO2-x). Based on this new understanding, we demonstrate the in situ formation of A-SMSI under reaction conditions, obviating the typically required CO2-rich pretreatment. The as-formed A-SMSI layer exhibits remarkable stability at various temperatures, enabling excellent activity, selectivity and long-term stability in catalyzing the reverse water gas-shift reaction. This study deepens the understanding of the A-SMSI and the ability to stabilize A-SMSI under reaction conditions represents a key step for practical catalytic applications.

Tuning the Metal-Support Interaction by Modulating CeO2 Oxygen Vacancies to Enhance the Toluene Oxidation Activity of Pt/CeO2 Catalysts.

In this research, a range of Pt/CeO2 catalysts featuring varying Pt-O-Ce bond contents were developed by modulating the oxygen vacancies of the CeO2 support for toluene abatement. The Pt/CeO2-HA catalyst generated a maximum quantity of Pt-O-Ce bonds (possessed the strongest metal-support interaction), as evidenced by the visible Raman results, which demonstrated outstanding toluene catalytic performance. Additionally, the UV Raman results revealed that the strong metal-support interaction stimulated a substantial increase in oxygen vacancies, which could facilitate the activation of gaseous oxygen to generate abundant reactive oxygen species accumulated on the Pt/CeO2-HA catalyst surface, a conclusion supported by the H2-TPR, XPS, and toluene-TPSR results. Furthermore, the results from quasi-in situ XPS, in situ DRIFTS, and DFT indicated that the Pt/CeO2-HA catalyst with a strong metal-support interaction led to improved mobility of reactive oxygen species and lower oxygen activation energies, which could transfer a large number of activated reactive oxygen species to the reaction interface to participate in the toluene oxidation, resulting in the relatively superior catalytic performance. The approach of tuning the metal-support interaction of catalysts offers a promising avenue to develop highly active catalysts for toluene degradation.

Origin of the synergistic effects of bimetallic nanoparticles coupled with a metal oxide heterostructure for accelerating catalytic performance

AbstractPrecisely tuning bicomponent intimacy during reactions by traditional methods remains a formidable challenge in the fabrication of highly active and stable catalysts because of the difficulty in constructing well‐defined catalytic systems and the occurrence of agglomeration during assembly. To overcome these limitations, a PtRuPNiO@TiOx catalyst on a Ti plate was prepared by ultrasound‐assisted low‐voltage plasma electrolysis. This method involves the oxidation of pure Ti metal and co‐reduction of strong metals at 3000°C, followed by sonochemical ultrasonication under ambient conditions in an aqueous solution. The intimacy of the bimetals in PtRuPNiO@TiOx is tuned, and the metal nanoparticles are uniformly distributed on the porous titania coating via strong metal‒support interactions by leveraging the instantaneous high‐energy input from the plasma discharge and ultrasonic irradiation. The intimacy of PtRuPNiO@TiOx increases the electron density on the Pt surface. Consequently, the paired sites exhibit a high hydrogen evolution reaction activity (an overpotential of 220 mV at a current density of 10 mA cm−2 and Tafel slope of 186 mV dec−1), excellent activity in the hydrogenation of 4‐nitrophenol with a robust stability for up to 20 cycles, and the ability to contrast stated catalysts without ultrasonication and plasma electrolysis. This study facilitates industrially important reactions through synergistic chemical interactions.

Unbounding the Future: Designing NiAl-based Catalysts for Dry Reforming of Methane.

Dry reforming of methane (DRM), the catalytic conversion of CH4 and CO2 into syngas (H2 + CO), is an important process closely correlated to the environment and chemical industry. NiAl-based catalysts have been reported to exhibit excellent activity, low cost, and environmental friendliness. At the same time, the rapid deactivation caused by carbon deposition, Ni sintering, and phase transformation exerts great challenges for its large-scale applications. This review summarizes the recent advances in NiAl-based catalysts for DRM, particularly focusing on the strategies to construct efficient and stable NiAl-based catalysts. Firstly, the thermodynamics and elementary steps of DRM, including the activation of reactants and coke formation and elimination, are summarized. The roles of Al2O3 and its mixed oxides as the support, and the influences of the promoters employed in NiAl-based catalysts over the DRM performance, are then illustrated. Finally, the design of anti-coking and anti-sintering NiAl-based catalysts for DRM is suggested as feasible and promising by tailoring the structure and states of Ni and the modification of Al-based supports including small Ni size, high Ni dispersion, proper basicity, strong metal-support interaction (SMSI), active oxygen species as well as high phase stability.

Facile synthesis of iron nanoparticles from Camellia Sinensis leaves catalysed for biodiesel synthesis from Azolla filiculoides

Recent years have seen an increase in research on biodiesel, an environmentally benign and renewable fuel alternative for traditional fossil fuels. Biodiesel might become more cost-effective and competitive with diesel if a solid heterogeneous catalyst is used in its production. One way to make biodiesel more affordable and competitive with diesel is to employ a solid heterogeneous catalyst in its manufacturing. Based on X-ray diffraction (XRD) and Fourier Transform infrared spectroscopy (FTIR), the researchers in this study proved their hypothesis that iron oxide core–shell nanoparticles were generated during the green synthesis of iron-based nanoparticles (FeNPs) from Camellia Sinensis leaves. The fabrication of spherical iron nanoparticles was successfully confirmed using scanning electron microscopy (SEM). As a heterogeneous catalyst, the synthesised catalyst has shown potential in facilitating the conversion of algae oil into biodiesel. With the optimal parameters (0.5 weight percent catalytic load, 1:6 oil—methanol ratio, 60 °C reaction temperature, and 1 h and 30 min reaction duration), a 93.33% yield was attained. This may be due to its acid–base property, chemical stability, stronger metal support interaction. Furthermore, the catalyst was employed for transesterification reactions five times after regeneration with n-hexane washing followed by calcination at 650 °C for 3 h.

Strong Metal-Support Interaction Modulation between Pt Nanoclusters and Mn3O4 Nanosheets through Oxygen Vacancy Control to Achieve High Activities for Acidic Hydrogen Evolution.

The optimization of metal-support interactions is used to fabricate noble metal-based nanoclusters with high activity for hydrogen evolution reaction (HER) in acid media. Specifically, the oxygen-defective Mn3O4 nanosheets supported Pt nanoclusters of ≈1.71nm in diameter (Pt/V·-Mn3O4 NSs) are synthesized through the controlled solvothermal reaction. The Pt/V·-Mn3O4 NSs show a superior activity and excellent stability for the HER in the acidic media. They only require an overpotential of 19mV to drive -10mAcm-2 and show negligible activity loss at -10 and -250mAcm-2 for >200 and >60h, respectively. Their Pt mass activity is 12.4 times higher than that of the Pt/C and even higher than those of many single-atom based Pt catalysts. DFT calculations show that their high HER activity arises mainly from the strong metal-support interaction between Pt and Mn3O4. It can facilitate the charge transfer from Mn3O4 to Pt, optimizing the H adsorption on the catalyst surface and promoting the evolution of H2 through the Volmer-Tafel mechanism. The oxygen vacancies in the V·-Mn3O4 NSs are found to be inconducive to the high activity of the Pt/V·-Mn3O4 NSs, highlighting the great importance to reduce the vacancy levels in V·-Mn3O4 NSs.

Modulation of metal–support interactions in Pt–TiOx synergistic catalysts for propane dehydrogenation

The strong metal-support interaction exerts a significant influence on the catalytic performance of the metal active site. This paper describes the modulation of the coverage of TiOx on the Pt nanoparticles via the pretreatment atmosphere, and its influence of the catalytic performance for propane dehydrogenation. The direct reduction in H2 at 600 °C of the Pt/TiO2-Al2O3 catalyst induces partial coverage of the Pt nanoparticles by TiOx. This partial coverage with TiOx leads to higher electron density over platinum than catalysts treated through air calcination followed by reduction, which can enhance the selectivity of propylene. Furthermore, the presence of TiOx in the catalysts can promote C–H activation during propane dehydrogenation. Eventually, this synergistic catalyst presents a high formation rate of propylene (141.1 mmol·gcat-1·h−1) and propylene selectivity of ∼ 91 % with a low deactivation rate of 0.09 h−1. This study unveils an effective approach to modulate the catalytic performance of metals supported on oxides based on metal-support interaction.

Adjusting Ag0 on oxygen-deficient Ag/MnO2 through electronic metal-support interaction to enhance mineralization of toluene in post-plasma catalytic system

While nonthermal plasma (NTP) technology exhibits notable efficacy in removing volatile organic compounds (VOCs), its practical application is impeded by a restricted carbon dioxide (CO2) selectivity. In this work, Ag-loaded α-MnO2 nanorods with strong electronic metal-support interaction (EMSI) were synthesized to enhance the mineralization of toluene in post-plasma system (PPC). EMSI was constructed between Ag species and MnO2 by anchoring Ag on hydroxyl groups. Increasing Ag loading facilitated the generation of oxygen vacancies, which promoted electron transfer from MnO2 to Ag sites, reinforcing EMSI and favoring the formation of Ag0. The results showed that the 3% Ag-loaded α-MnO2 nanorods exhibited better activity than bare MnO2, with a remarkable boost in CO2 selectivity to 77.5%, far exceeding the 33% CO2 selectivity of MnO2. It was concluded that both oxygen vacancies and Ag0 affected the toluene conversion by enhancing the conversion of ozone (O3) to reactive oxygen species (ROS). Through in-situ DRIFTS, it was found that Ag0 transformed O3 to a higher concentration of atomic oxygen (O*), capable of degrading organic intermediates to CO2. Additionally, Ag0 facilitated the direct ring-opening of adsorbed toluene. This research introduces a novel method for designing catalysts with EMSI to improve the mineralization of VOCs.

Electrostatic Self-Assembly Synthesis of Pd/In2O3 Nanocatalysts with Improved Performance Toward CO2 Hydrogenation to Methanol.

CO2 hydrogenation to methanol has emerged as a promising strategy for achieving carbon neutrality and mitigating global warming, in which the supported Pd/In2O3 catalysts are attracting great attention due to their high selectivity. Nonetheless, conventional impregnation methods induce strong metal-support interaction (SMSI) between Pd and In2O3, which leads to the excessive reduction of In2O3 and the formation of undesirable PdIn alloy in hydrogen-rich atmospheres. Herein, we innovatively synthesized Pd/In2O3 nanocatalysts by the electrostatic self-assembly process between surface-modified composite precursors with opposite charges. And the organic ligands concurrently serve as Pd nanoparticle protective agents. The resultant Pd/In2O3 nanocatalyst demonstrates the homogeneous distribution of Pd nanoparticles with controllable sizes on In2O3 supports and the limited formation of PdIn alloy. As a result, it exhibits superior selectivity and stability compared to the counterparts synthesized by the conventional impregnation procedure. Typically, it attains a maximum methanol space-time yield of 0.54 gMeOH h-1gcat -1 (300 °C, 3.5 MPa, 21,000 mL gcat -1 h-1). Notably, the correlation characterization results reveal the significant effect of small-size, highly dispersed Pd nanoparticles in mitigating MSI. These results provide an alternative strategy for synthesizing highly efficient Pd/In2O3 catalysts and offer a new insight into the strong metal-support interaction.

Tune and turn the pyrolysis of metal organic frameworks towards stable supported nickel catalysts for the dry reforming of methane

Dry reforming of methane (DRM) is an inimitable approach for eliminating both greenhouse gases, methane and CO2, while producing synthesis gas which further can be converted to added-value fuels. However, the industrialization of DRM has been limited due to sintering and coking to the catalysts under the harsh reaction conditions. Here, we propose a new methodology for producing tunable supported nickel-based catalysts for DRM using metal organic frameworks (MOFs) as precursors of the catalyst components. In particular, Ni- and La-MOFs were coalesced using sonication and then calcined at different temperatures to produce catalysts with tailored Ni metal size (5–20 nm) and tuned strong metal-support interactions (SMSI). Here, the synthesis of nickel and nickel oxide nanoparticles embedded on lanthanum-based supports by controlled calcination of the MOF structures is demonstrated; the Ni supported catalysts were then used for DRM reaction. Among the developed catalysts, the catalyst produced following calcination at 500 °C (Ni-La-500) has shown stable and high CH4 conversion rates under DRM conditions at 800 °C with negligible carbon formation at elevated gas hourly space velocities. Further, the catalytic performance of Ni-La-500 catalyst (sonicated) was compared to the physically mixed MOFs derived catalyst (Ni-La-500-PM), conventional wetness impregnated catalyst (Ni-La-500 WI), Ni-MOF derived unsupported catalyst (Ni-500), and lower Ni concentration catalyst (sonicated, 10Ni-La-500). The observed CH4 conversion rates at 50,000 mL·gcat–1·h−1 GHSV are 81.8, 67.9, 85.4, 34.7, and 57.9 % for Ni-La-500, Ni-La-500 PM, Ni-La-500 WI, Ni-500, and 10Ni-La-500 catalysts, respectively after 24 h of DRM reaction. With isotopic studies, it was found that the 18O exchange rate was higher in case of Ni-La-500-PM catalyst (8.1 mmol·g−1) as compared to Ni-La-500 catalyst (5.5 mmol·g−1). Prior interaction between MOFs, calcination temperatures, reaction conditions, and the carbon pathways during catalytic activity dictates the conversion rates and selectivity of the products. Overall, with the herein proposed approach of MOF-derived supported catalysts exceptional conversion rates and stability during the DRM reaction with nominal coking and sintering were demonstrated, solving the two major challenges faced by conventional and unsupported catalysts.

Crystalline phase-modulated PtOx nanoparticles exhibit superior methane combustion performance and sulfur poisoning resistance: Multi-interaction regulation

Up to now, methane combustion catalysts generally suffer from issues such as poor reaction stability and susceptibility to sulfur poisoning, which have become the key factors restricting their application, so it is necessary to construct catalysts with excellent chemical stability of the active center and strong sulfur resistance. Here, we showed the crystal phase-modulated state of PtOx nanoparticles (PtOx NPs) on TiO2 and investigated their effects on the reactivity of methane catalytic combustion and anti-SO2 poisoning properties. It was found that Pt/r-TiO2 showed superior activity, stability, and resistance to SO2 poisoning. Transmission electron microscope (TEM) images showed that the PtOx NPs on the surface of r-TiO2 were much more stable than a-TiO2 for the reason that the Ostwald ripening of PtOx NPs on a-TiO2 was facilitated due to the strong metal-support interaction (MSI) between PtOx NPs and TiO2 and the low migration energy of the PtOx NPs on TiO2, while they were moderate of Pt/r-TiO2, and then the active sites were stabilized during methane combustion. The activity was controlled by the size and electronic structure of PtOx NPs, which were stable on the surface of r-TiO2 with a higher Pt4+ content, and the density functional theory (DFT) calculations further revealed the role of r-TiO2 in increasing the quantities of surface oxygen vacancies. Moreover, the SO2 tolerance of Pt/r-TiO2 was also the best among all kinds of Pt-based catalysts prepared, which was attributed to the minimal adsorption energy (Ead) of SO2 on r-TiO2, and the absence of sulfate and sulfite deposition on the Pt/r-TiO2 catalyst confirmed by TGA and in-situ DRIFTS studies on SO2 adsorption. In this research, the anti-SO2 poisoning and reaction stability were realized by adjusting the interaction between SO2, active components, and supports, which provided a new insight for the design of stable Pt-based SO2-resistant catalysts.

Unraveling the Unique Strong Metal-Support Interaction in Titanium Dioxide Supported Platinum Clusters for the Hydrogen Evolution Reaction.

Strong metal-support interaction (SMSI) is crucial to modulating the nature of metal species, yet the SMSI behaviors of sub-nanometer metal clusters remain unknown due to the difficulties in constructing SMSI at cluster scale. Herein, we achieve the successful construction of the SMSI between Pt clusters and amorphous TiO2 nanosheets by vacuum annealing, which required a relatively low temperature that avoids the aggregation of small clusters. In situ scanning transmission electron microscopy observation is employed to explore the SMSI behaviors, and the results reveal the dynamic rearrangement of Pt atoms upon annealing for the first time. The originally disordered Pt atoms become ordered as the crystallizing of the amorphous TiO2 support, forming an epitaxial interface between Pt and TiO2. Such SMSI state can remain stable in oxidation environment even at 400 °C. Further investigations prove that the electron transfer from TiO2 to Pt occupies the Pt 5d orbitals, which is responsible for the disappeared CO adsorption ability of Pt/TiO2 after forming SMSI. This work not only opens a new avenue for constructing SMSI at cluster scale but also provides in-depth understanding on the unique SMSI behavior, which would stimulate the development of supported metal clusters for catalysis applications.

Unraveling the Unique Strong Metal‐Support Interaction in Titanium Dioxide Supported Platinum Clusters for the Hydrogen Evolution Reaction

Strong metal‐support interaction (SMSI) is crucial to modulating the nature of metal species, yet the SMSI behaviors of sub‐nanometer metal clusters remain unknown due to the difficulties in constructing SMSI at cluster scale. Herein, we achieve the successful construction of the SMSI between Pt clusters and amorphous TiO2 nanosheets by vacuum annealing, which required a relatively low temperature that avoids the aggregation of small clusters. In situ scanning transmission electron microscopy observation is employed to explore the SMSI behaviors, and the results reveal the dynamic rearrangement of Pt atoms upon annealing for the first time. The originally disordered Pt atoms become ordered as the crystallizing of the amorphous TiO2 support, forming an epitaxial interface between Pt and TiO2. Such SMSI state can remain stable in oxidation environment even at 400 °C. Further investigations prove that the electron transfer from TiO2 to Pt occupies the Pt 5d orbitals, which is responsible for the disappeared CO adsorption ability of Pt/TiO2 after forming SMSI. This work not only opens a new avenue for constructing SMSI at cluster scale but also provides in‐depth understanding on the unique SMSI behavior, which would stimulate the development of supported metal clusters for catalysis applications.

Atmosphere-Dependent Strong Metal–Support Interactions in Au/ZnO Catalysts and Their Overlayer Permeability

Atmosphere-Dependent Strong Metal–Support Interactions in Au/ZnO Catalysts and Their Overlayer Permeability

Facile synthesis of Ni-phyllosilicate assisted by polyacrylamide at room temperature for CO2 hydrogenation to methane

To elucidate the effect of solution viscosity on the synthesis of Ni-phyllosilicate, polyacrylamide was incorporated to create a viscous aqueous medium containing of sodium metasilicate, nickel nitrate and NH4F. The enhanced viscosity promotes the dispersion of the initial formed crystal seeds and the growth of Ni-phyllosilicate, culminating in a Ni-rich NiPs-RT-6 of a high Ni content of up to 55.2 wt%. Residual polyacrylamide elimination was accomplished via calcination, concurrently enhancing metal-support interaction. The as-synthesized samples display a nanoflower morphology with nanospheres overlaid with numerous thin nanosheets. The relatively small Ni particles around 5.7 nm were obtained after reduction even at a very high Ni loading, owing to its strong metal-support interaction. NiPs-RT-6 achieves a CO2 conversion of 75.9% at 450 °C, 0.1 MPa, 60 L g−1·h−1, which closely approximates thermodynamic equilibrium. The turn over frequency for CO2 (TOFCO2) was substantial, calculated at 3.7 × 10−3 s−1, accompanied by activation energy (Ea) of 80.6 kJ·mol–1. In-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) further disclosed that m-HCOO– serves as a crucial intermediate following a formate reaction pathway. With its high Ni content, finely distributed Ni particles, and strong metal-support interaction, NiPs-RT-6 demonstrates promising catalytic activity in CO2 methanation.

Co-ZIF reinforced kraft lignin biochar as an efficient catalyst for highly selective hydrodeoxygenation of lignin-derived chemicals

Large amount of lignin was produced annually as a byproduct in papermaking and pulping processes, the challenges in disposal methods had posed serious obstacles for advanced carbon materials and value-added chemicals. This study involved the preparation of kraft lignin (KL) loaded metal–organic framework (ZIF-67) material derived Co nanoparticles carbon using various methods to produce kraft lignin biochar-based carbon materials (Co@NPC-KLB). The novel and advanced carbon materials was utilized for lignin derived bio-oil hydrodeoxygenation to generate high value fuels and chemicals. It could achieve nearly 100 % vanillin (VAN) conversion and 88.49 % 2-methoxy-4-methylphenol (MMP) without the extra hydrogen at 240 °C in ethanol. The results demonstrated that highly active and stable Co nanoparticles, large specific surface area, smaller nano Co nanoparticles, strong metal-support interaction and rich Lewis acid sites on the surface of biochar support exhibited a positive promoting effect on VAN hydrodeoxygenation to generate MMP. Furthermore, density functional theory (DFT) also confirmed that synergistic effect of Co nanoparticles and kraft lignin biochar promoted a high adsorption energy of VAN on the surface of kraft lignin biochar, enhanced the catalytic ability of the hydrodeoxygenation process. This study provided a novel approach for utilizing kraft lignin in preparation functional catalysts, opening up new opportunities for designing efficient biochar-based materials for advanced carbon materials and high-value chemicals.

Enhancing Pd Catalytic Activity by Amine Group Modification for Efficient Direct Synthesis of H2O2.

A great deal of research has been carried out on the design of Pd-based catalysts in the direct synthesis of H2O2, mainly for the purpose of improving the H2O2 selectivity by weakening the activation energy on the Pd active site and thus inhibiting the dissociation of the O-O bonds in O2*, OOH*, and HOOH*. However, this often results in insufficient activation energy for the reaction between H2 and O2 on Pd, leading to difficulties in improving both the selectivity and productivity of H2O2 simultaneously. Based on this, this study reports an efficient catalyst composed of amine-functionalized SBA-15-supported Pd. The strong metal-support interaction not only makes the PdNPs highly dispersed with more Pd active sites but also improves the stability of the catalyst. The amine group modification increases the proportion of Pd0, further enhancing Pd activity and promoting the adsorption and conversion of H2 and O2 on Pd, thereby significantly increasing H2O2 productivity. Additionally, the density-functional theory simulation results showed that due to the hydrogen-bonding force between the amine group and H2O2, this particular anchoring effect would make the hydrogenation and decomposition of H2O2 effectively suppressed. Ultimately, both the selectivity and productivity of H2O2 are improved simultaneously.