Incipient Wetness Impregnation Method Research Articles

Effect of Hierarchical Architecture of Nickel Modified Mesoporous Catalysts on the Knoevenagel Condensation Reaction

AbstractA series of ordered mesoporous silicas (MCM‐41, SBA‐15 and KIT‐6) were successfully synthesized and modified with nickel by incipient wetness impregnation method. The supports and catalysts were characterized by N2 adsorption‐desorption, XRD, TEM, H2‐TPR, UV vis‐DR, XPS, ICP and Py FT‐IR techniques. All the materials were evaluated in the Knoevenagel condensation reaction between vanillin and malononitrile under microwave irradiation. The catalytic results show the key role that the chosen porous structure plays in the deposition of the active phase and its catalytic behaviour. Thus, by designing a suitable mesoporous catalyst it was possible to carry out such Knoevenagel condensation to obtain 2‐(4‐hydroxy‐3‐methoxybenzylidene) malononitrile through a highly efficient and environmentally friendly process, without solvents and reducing reaction times by employing microwave heating.

Hydrodesulfurization and isomerization performance of model FCC naphtha over sulfided Co(Ni)–Mo/Y catalysts

The process of deep hydrodesulfurization (HDS) in gasoline typically results in the saturation of olefins, leading to significant reductions in octane number. In this work, Y-supported Co(Ni)–Mo catalysts that with different Ni–Co content were prepared by the incipient wetness impregnation method, the structure and properties were characterized and analyzed using HRTEM, XPS, H2-TPR, and NH3-TPD. The isomerization of 1-hexene and 1-octene as well as the HDS of thiophene were studied by using model FCC naphtha. The incorporation of Ni was found to enhance the number of MoS2 stacking layers, thereby improving the degree of sulfurization in Mo and subsequently increasing the desulfurization rate, with a maximum achieved desulfurization rate of 94.7%. When employing a Ni/Co ratio of 3:2, optimal synergy between Ni and Co is achieved, resulting in a greater presence of multi-layer stacked II-Co(Ni)MoS active phases. Additionally, appropriate Brønsted acidity levels are maintained to facilitate efficient olefin isomerization while preserving high HDS activity. As a result, the current isomerization yield stands at 58.2%(mass). These understandings shed light on the development of highly HDS and olefin isomerization catalysts.

Fabrication of Highly Dispersed Ru Catalysts on CeO2 for Efficient C3H6 Oxidation.

Emissions of volatile organic compounds (VOCs) threaten both the environment and human health. To realize the elimination of VOCs, Ru/CeO2 catalysts have been intensively investigated and applied. Although it has been widely acknowledged that the catalytic performance of platinum group metal catalysts was highly determined by their dispersion and coordination environment, the most reactive structures on Ru/CeO2 catalysts for VOCs oxidation are still ambiguous. In this work, starting from Ce-BTC (BTC = 1,3,5-benzenetricarboxylic acid) materials, atomically dispersed Ru catalysts and agglomerated Ru catalysts were successfully created via one-step hydrothermal method (Ru-CeO2-BTC) and conventional incipient wetness impregnation method (Ru/CeO2-BTC), respectively. In a typical model reaction of C3H6 oxidation, atomically dispersed Ruδ+ species with the formation of abundant Ru-O-Ce linkages on Ru-CeO2-BTC were found to perform much better than agglomerated RuOx species on Ru/CeO2-BTC. Further characterizations and mechanism study disclosed that Ru-CeO2-BTC catalyst with atomically dispersed Ru ions and more superior low temperature redox performance compared to Ru/CeO2-BTC could better facilitate the adsorption/activation of C3H6 and the decomposition/desorption of intermediates, thus exhibiting superior C3H6 oxidation activity. This work elucidated the reactive sites on Ru/CeO2 catalysts in the C3H6 oxidation reaction and provided insightful guidance for designing efficient Ru/CeO2 catalysts to eliminate VOCs.

Fluidized-bed OCM reaction: A promising Mn2O3-Na2WO4/TiO2 catalyst and a numerical study

The fluidized-bed reactor with excellent heat and mass transfer features has great appeal for application in the oxidative coupling of methane (FB-OCM), whereas qualified fluid catalysts represent a grand challenge. Herein, we report a high-performance Mn2O3-Na2WO4/TiO2 fluid catalyst (5.4 wt% Mn2O3 and 2 wt% Na2WO4), which was obtained by the incipient-wetness impregnation method and examined in the OCM reaction in an electric-heating quartz fluidized-bed reactor (i.d., 2 cm). The standard normalization method on the basis of carbon atom was used for calculating the CH4 conversion and C2-C3 selectivity. This catalyst achieves 35.5 % CH4 conversion, 66 % C2-C3 selectivity and particularly 15.1 % single-pass yield of C2H4 for a feed of CH4/O2/H2O=3/1/1 with a catalyst dosage of 20 mL at 700 °C and a total GHSV of 7200 h−1. Such catalyst is stable for at least 50 h without signs of deactivation and agglomeration/defluidization. The catalyst particle size is crucial for the FB-OCM reaction with respect to the reaction light-off and catalyst fluidization. The catalyst with preferable particle size of 450–600 μm can not only trigger the OCM reaction at a relatively low temperature of 630 °C but also warrant active bubbling fluidization. Furthermore, thanks to the low amount of Na2WO4 and interpenetrating structure of TiO2-nanorod, such catalyst achieves good anti-aggregation and robust mechanical strength (with a low attrition index of 1.9 %). The effects of water-adding amount in feedstock and catalyst particle size distribution on the hydrodynamics behaviour were investigated in a laboratory-scale fluidized-bed OCM reactor by using numerical simulation method.

Cobalt‐Potassium Synergistic Modification Effects on Fe‐Based Catalysts for CO2 Hydrogenation to Low‐Carbon Olefins

ABSTRACTTo enhance the CO2 hydrogenation activity and low‐carbon olefin selectivity of Fe‐based catalysts, a strategy involving the use of metal promoters to modulate the structure of active metal centers in catalyst preparation was proposed. The incipient wetness impregnation method was used to introduce modifying agents K and/or Co into the Fe/Al2O3 catalyst. Characterization techniques such as XRD, BET, SEM, HRTEM, H2‐TPR, XPS, CO2‐TPD, NH3‐TPD, and TG were employed to investigate the effects of the modifying agents on the dispersion, reducibility, electronic properties, and acid–base properties of active metal species. Furthermore, the influence of K and Co modification on the CO2 hydrogenation activity and low‐carbon olefin selectivity of Fe/Al2O3 catalysts was explored. The results revealed that the introduction of K generated more basic sites and electron‐rich active metal centers in the catalyst, facilitating the adsorption and activation of CO2, while suppressing the hydrogenation of olefins and the formation of methane, thus improving the selectivity towards low‐carbon olefins. Co promoter facilitated the dispersion of Fe species, exposing more active sites and enhancing the FTS reaction activity, leading to more CO being converted into C2+ hydrocarbon products. Under the synergistic effect of K and Co, the CO2 conversion activity of the Fe‐based catalyst significantly increased, achieving a CO2 conversion rate of 37%, while the selectivity towards C2‐C4= increased to 31.9%.

CO2‐Hydrogenation to Methanol over CuO/ZnO Based Infiltration Composite Catalyst Spheres

AbstractMultiple active component catalysts for efficient conversion of CO2 to Methanol (MeOH) are synthesized through coating γ‐Al2O3 carrier spheres by incipient wetness impregnation method (IWI). The well‐known bimetallic Copper Oxide/Zinc Oxide (CuO/ZnO)is promoted in three steps, first by Cerium Oxide (CeO2), then additionally with Zirconium Oxide (ZrO2) and finally with Calcium Oxide (CaO) resulting in four carrier catalysts with high surface area and catalyst pore volume. Quaternary and quinary carrier catalysts promoted with moderate CeO2, ZrO2 in the quaternary (20 % CZCZ) and additionally with CaO (20 % CZCZC) in the quinary catalysts demonstrate high CO2‐conversion ratios (16.2 % and 18.7 %) and space time yields (0.51 and 0.47 gMeOH h−1 gCatalyst−1) at 5 MPa and 250 °C. The high conversion ratios (XCO2) and good methanol space‐time‐yields (STYMeOH) are attributed to enhanced copper dispersion and several multi metal oxide component interactions essential to enhance CO2‐activation and ‐conversion through the catalytic systems as well as very high overall surface area. Compared to related studies, the carrier catalysts show superior conversion rates, proving the effectiveness of the introduced multi‐component carrier catalyst and extending the understanding of infiltrate composites as possible large‐scale application alternatives to precipitated MeOH catalyst systems.

Uncovering the roles of Ce and Mn for NH3-SCR over Mn-Ce/IM-5 with extraordinarily superior wide-temperature performance

The development of wide-temperature catalyst with glorious activity and the resistance of SO2 for NH3-SCR reaction are of great importance. However, the preparation of wide-temperature catalyst with outstanding NH3-SCR performance and the resistance of SO2 is still challenging. In this work, Mn and Ce modified IM-5 molecular sieve catalyst (MC-5) was synthesized by incipient wetness impregnation method and the relationship of structure-activity was studied. MC-5 exhibited superior NOx conversion and it was more than 87% in the temperature range of 150-500 °C and ca. 100% at 225 °C due to the high concentration of Mn4+ and chemisorbed oxygen, the excellent redox ability and the synergistic effect of Mn and Ce. Meanwhile, the redox cycle of Mn4++Ce3+↔Mn3++Ce4+ promoted the electron transfer. 27Al NMR spectra and NH3-TPD confirmed Mn ion was mainly located on the bridge hydroxyl group (Brønsted acid sites). The localization energies ΔE of (Al, Mn) for IM-5 was determined by theoretical calculation and the reaction mechanism of M-5 catalyst on Brønsted acid sites was proposed. The reaction mechanism of M-5 catalyst on Brønsted acid sites followed L-H mechanism. And interestingly enough, the NH3-SCR activity of MC-5 significantly increased in the presence of SO2 at 200 °C. One of the reasons was that Ce binded more easily to SO42- and thus protected the active site Mn from sulfation. The other reason was the generation of more acid sites.

Impact of various metal promoters on the propane dehydrogenation performance of cobalt-based catalysts

Large-scale exploitation of natural gas and shale gas has spurred the development of the propane dehydrogenation technology. While cobalt-based catalysts, known for their low cost and low toxicity, effectively activate C–H bonds, they are often deactivated because of coke formation. In this study, we prepared SBA-15 molecular sieves using a hydrothermal synthesis method and developed a series of Co-based catalysts supported on SBA-15 with various metal promoters (denoted Co-X/SBA-15, where X = Mn, Fe, Mg, Zn, or La) via an incipient wetness impregnation method. Characterization techniques and activity evaluation results revealed that the Co–O–Mg structure in the Co-Mg/SBA-15 catalyst stabilizes the primary Co2+ active site and hinders the reduction of the CoOx species. The incorporation of Mg enhances the total alkalinity of the catalyst, facilitating propane adsorption and propylene desorption, leading to superior activity and stability. Although the addition of La improved propylene selectivity, it did not significantly enhance propane conversion. Conversely, the introduction of Mn, Fe, and Zn into the catalyst inhibited the reaction.

Synergistic Effect of RuCo and Hierarchical ZSM‐5 for Enhanced Hydrogen Generation

AbstractA unique bifunctional catalyst comprised of acid site containing, hierarchical ZSM‐5 (contains acid sites) supported RuCo bimetal, was synthesized using a facile incipient wetness impregnation method. The synergistic interaction between zeolite acid sites and bimetals of this bifunctional material significantly improves its performance as a catalyst of hydrogen producing, dehydrogenation of ammonia borane.

Study on the Synergistic Effect of SiO2 and H2O on Oxidative Coupling of Methane over Mn-Na2WO4/SiO2 Catalyst.

Mn-Na2WO4-based catalysts with different supports were prepared using the incipient wetness impregnation method and evaluated for their oxidative coupling of methane (OCM) reaction performance. The results demonstrated that the SiO2- supported catalyst exhibited the best catalytic performance, and the introduction of H2O further enhanced its activity. Under the conditions of a feed gas mixture of CH4/O2/H2O = 6:1:24 at 800 °C and atmospheric pressure, the CH4 conversion and C2+ selectivity over the Mn-Na2WO4/SiO2 catalyst increased from 28.4% and 77.4% (without H2O) to 33.2% and 84.9%, respectively. In contrast, the catalytic activity using TiO2 and MgO supports drastically declined. Characterizations using X-ray diffraction (XRD), in situ infrared spectroscopy (In-situ IR), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H2-TPR), and oxygen temperature-programmed desorption (O2-TPD) revealed that the introduction of steam not only served as a diluent to decrease the partial pressures of the reactants CH4 and O2, thereby reducing deep oxidation reactions in the gas phase, but also interacted with surface oxygen species (O2 2-) and silica to form adjacent surface-bonded disilanol free radicals Si-OIH. This interaction facilitated the dehydrogenation and coupling of two methane molecules on the catalyst surface, resulting in the generation of C2+ products, significantly enhancing the catalytic activity and selectivity of OCM.

Partial substitution of rhodium with ruthenium in Pd-Rh nanoalloys and its impact on catalytic characteristics

In the present work, alumina-supported trimetallic Pd-Rh-Ru catalysts were synthesized and studied in comparison with the bimetallic Pd-Rh reference sample. The alloy nanoparticles were formed on the surface of the alumina support by thermolysis of the complex salts [Rh(NH3)5Cl][Pd(NO2)4] and [Rh(NH3)5Cl]0.5[Ru(NH3)5Cl]0.5[Pd(NO2)4], preliminary deposited via an incipient wet impregnation method. The influence of the conditions of the thermolysis process on the phase composition of the final products and the size of the trimetallic particles was established. Thus, nanoscale trimetallic (Rh-Ru-Pd) alloy particles of a given composition were obtained. The catalytic performance of the alumina-supported samples was examined in a CO oxidation reaction under prompt thermal aging conditions. It was ascertained that the addition of ruthenium only improves both the initial activity and thermal stability of the catalytic system. The state of each metal in the alloy nanoparticles was characterized by diffuse reflectance UV–vis spectroscopy and X-ray photoelectron spectroscopy.

The Utilization of Rice Husk as Both the Silicon Source and Mesoporous Template for the Green Preparation of Mesoporous TiO2/SiO2 and Its Excellent Catalytic Performance in Oxidative Desulfurization.

In recent years, TiO2-based catalysts have received extensive attention from researchers for their excellent oxidative desulfurization (ODS) performances. In this paper, a series of mesoporous TiO2/SiO2 catalysts with different TiO2 loadings are prepared, using an incipient wetness impregnation method with agricultural waste rice husk as both the silicon source and mesoporous template and tetrabutyl titanate as the titanium source. The effect of different TiO2 loadings on the ODS performance of the samples is investigated, and the appropriate TiO2 loading is 2.5%. Compared with pure TiO2, the 2.5%TiO2/SiO2 sample exhibits high catalytic activity for oxidative desulfurization. This is, on the one hand, due to the high specific surface area and mesopore volume of the 2.5%TiO2/SiO2 sample. On the other hand, it is due to the uniform dispersion of TiO2 grains with an average diameter of 6.1 nm on the surface of the mesoporous SiO2 carrier, which greatly increases the active sites of the 2.5%TiO2/SiO2 sample, thus improving the catalytic activity of the sample. The recycling performances of the 2.5%TiO2/SiO2 sample are further investigated. The results show that, after fifteen cycles, the 2.5%TiO2/SiO2 sample still maintains high conversions of dibenzothiophene (99.8%) and 4,6-dimethyldibenzothiophene (99.7%) without deactivation. In addition, the 2.5%TiO2/SiO2 sample treated with TBHP aqueous solution is characterized by the technique of UV-Vis, and the Ti-peroxo (Ti-OOtBu) species, the active intermediate for the ODS of bulky organic sulfides, is successfully captured. Finally, a possible reaction mechanism for the ODS process over the 2.5%TiO2/SiO2 sample is proposed.

Advancements in biomass conversion: Copper-catalyzed anaerobic dehydrogenation of 5-hydroxymethylfurfural to 2,5-diformylfuran

Developing cost-effective and inherently safe methods for accelerating the sustainable production of value-added chemicals from biomass presents a promising solution to the current energy crisis. This study introduces heterogeneous copper species anchored on a γ-Al2O3 catalyst (Cu/γ-Al2O3) with high dispersibility and small Cu particle size, synthesized via a straightforward incipient-wetness impregnation method. This method facilitates the selective anaerobic dehydrogenation of 5-hydroxymethylfurfural (HMF) into 2,5-diformylfuran (DFF) in the absence of any oxidant or hydrogen acceptor. An HMF conversion of 69.8 % and a DFF yield of 44.9 % were attained at 130 °C over a 12-h period. Extensive characterizations were conducted to elucidate the correlation between the catalyst’s structure and its dehydrogenation activity. The findings indicated that strong L-acid sites, elevated Cu dispersions, small Cu particle size and an increased number of Cu+ active sites were conducive to enhanced dehydrogenation reactivity. The Cu/γ-Al2O3 catalyst demonstrated superior catalytic efficiency and stability. A possible reaction mechanism is suggested, integrating DFT calculations with experimental observations. This research offers valuable insights into the selective conversion of HMF to DFF and encourages further exploration into the dehydrogenation of biomass alcohols into high-value chemicals under oxidant-free conditions.

An experimental study of the endothermic catalytic cracking of hydrocarbon aviation fuels under extreme conditions

Methylcyclohexane (MCH) is a suitable surrogate endothermic fuel that can operate under extreme conditions and it can be utilized to better understand the mechanisms of endothermic catalytic cracking and coke generation in jet engines. Zn-impregnated desilicated Zeolite Socony Mobil–5 (ZSM-5) zeolite catalysts have been successfully prepared and studied for aviation fuel cracking under high temperature and pressure conditions (550 °C; 50 bar). First, micropore ZSM-5 was desilicated by the alkali treatment method with NaOH to increase the mesopore distributions. In the second step, Zn-doped mesopore ZSM-5 zeolites were prepared by the incipient wetness impregnation method with an aqueous solution of zinc nitrate. After the endothermic pyrolysis of MCH fuel over the modified zeolite catalysts, the condensed liquid product fraction (%) was analyzed. It can be deduced that a reasonable combination of these advanced synthesis strategies can increase catalytic cracking performance. This study showed that, in the context of endothermic catalytic cracking of hydrocarbon aviation fuels at supercritical jet conditions, Zn-doped desilicated zeolites exhibited a decreased quantity of coke deposition.

Copper-loaded sustainable MOFs as photocatalysts for dye removal

This work presents the effect of Cu loading, using incipient wetness impregnation method, on sustainably synthesized MIL-100(Fe), NH2-MIL-53(Al), Zr-BDC and NH2-Zr-BDC MOFs and their photocatalytic removal efficiency on target dye, rhodamine B (RhB), from aqueous solutions. Several Cu ratios have been tested, finding that 2 wt% of Cu load becomes optimum in terms of metal distribution and catalytic performance. Powder X-ray diffraction patterns (XRD) showed no difference from the parent supports in the case of MIL-100(Fe), NH2-MIL-53(Al) and Zr-BDC, whereas extra peaks are induced by Cu impregnation in NH2-Zr-BDC. In addition, several techniques indicate that Cu strongly interacts with the MOF in Cu@NH2-Zr-BDC, exhibiting the lowest bandgap of the series, the lowest photoluminescence intensity and a notable predominance of Cu in the oxidation state 2+. The above evidences lead Cu@NH2-Zr-BDC to behave as the most effective catalyst in the removal of RhB, reaching removal efficiency as high as 93 %, being able to efficiently and selectively remove basic dyes from mixed samples, such as RhB and MB, but not for acidic dyes like MO, and also showing a very good performance (46 % photodegradation) in real waste water from Hawassa textile factory, in Ethiopia. Moreover, this catalyst can be recycled 3 times by simple washing and drying. Scavengers test suggested that h+ is the most active species in the photocatalytic degradation.

Enhancement of selective monoaromatic hydrocarbon and syngas products from fast pyrolysis of cassava stalks over Co, Mo promoted Ni catalysts

Catalytic fast pyrolysis of cassava stalks has been intriguing as a promising, feasible chemical refinery method in terms of waste-to-energy conversion from cassava cultivation. This study aims to determine the synergetic influence of Mo and Co on Ni catalysts (Ni, Ni–Mo, and Ni–Co) prepared via ultrasonic-assisted incipient wetness impregnation method for catalytic pyrolysis vapor upgrading. The results indicated that Co and Mo enhance the reducibility of NiO and promote weak-to-medium acidity, thereby enhancing Ni's performance. Mono-Ni favors cracking deoxygenation, whereas oxophilicity promoters particularly enhance the oxygen absorbability efficiency to selective deoxygenated production. A fine Ni dispersion on CoNi/SiO2 catalyst was observed to positively affect the production of monoaromatic hydrocarbons (46.10 %), in contrast to those without promoters (21.63 %). This is attributed to an optimal Ni-metallic distribution with a small crystal size of 7.01 nm and a high surface area of 342.6 m2 g−1, highlighting the effectiveness of the promoter-assisted Ni catalyst. Additionally, a high yield of H2 (66.9 %) in non-condensable gas was recorded at 550 °C. The study suggests that a simplified approach to developing Ni-based catalysts could enhance the eco-friendliness of commercial catalysts, thereby facilitating the scale-up of biomass pyrolysis applications.

Efficient catalysis of acetylene semi-hydrogenation through synergistic action of supported ionic liquid-nickel catalyst

In the semi-hydrogenation of acetylene, nickel-based catalysts offer a promising alternative to precious metal palladium catalysts. Despite the positive hydrogenation activity of nickel-based catalysts, there is still room for improvement in terms of their selectivity and stability. In this study, a simple incipient wetness impregnation method was employed to prepare Ni(OAC)2-IL/Al2O3 catalyst and its performance in the selective hydrogenation of acetylene was investigated. It was found that under the conditions of 170 °C and a space velocity of 600 h−1, the 3 % Ni(OAC)2-IL/Al2O3 catalyst achieved a 95.3 % acetylene conversion with an 85.6 % ethylene selectivity. Furthermore, the catalyst exhibited outstanding stability over a 100 hour test. TEM, XPS and C2H4-TPD experiments showed that the Ni species were encapsulated in the ionic liquids (ILs), and the interaction between the metal ions, nickel, and the ILs ensured a high dispersion and stability of the actives on the carriers, and the electronic effect between the ionic nickel and the ionic liquids increased the electron cloud density of the Ni, which improved the catalyst selectivity, which is the main reason for its excellent catalytic performance.

Revealing the mechanisms of NH3 adsorption and reactions in catalytic NOx reduction over Cux/CHA zeolites by in situ DRIFTS spectroscopy

Adsorption and activation of NH3 on Cu-SSZ-13 were essential for NOx removal, however, their important role at the molecular level remains unclear. In this work, the Al-rich Cu/SSZ-13 (Cux/CHA) catalysts were synthesized by the incipient-wetness impregnation method, and the NH3-SCR performance was investigated. It is found that high Cu content promoted the formation of Z-[Cu(OH)]+ and CuOx particles, enhanced the adsorption capacity of NOx, and increased the intra-zeolite oxolation process in the Cux/CHA catalysts. In situ DRIFTS results showed that the Z-[Cu(OH)(NH3)x]+(x<3) exhibited analogous properties to B-NH4+, but it would convert to Z-[Cu(OH)(NH3)3]+ with increasing NH3 adsorption time and exhibit L-NH3 properties. Those findings could provide a new insight into understanding the adsorption and activation of NH3 in low-temperature reactions, as well as new ideas for improving NOx conversion during cold start.

Insights into the Construction of Robust Pt Clusters with Satisfactory Stability on CeO2 for the Catalytic Oxidation of CO.

Improving the efficiency of platinum group metals (Pt, Pd, Rh, etc.) in catalytic oxidation reactions remains an urgent topic. The conflict between the low-temperature activity and high-temperature stability of noble metals can hardly reach a consensus. For instance, Pt cluster catalysts supported on CeO2 with high low-temperature activity will suffer from deactivation due to the redispersion under high-temperature lean-burn reaction conditions. Herein, two Pt1/CeO2 prepared by the incipient wetness impregnation method using different Pt precursors possessed varied Pt-O and Pt-O-Ce coordination numbers (CNs). They showed various priorities in CO oxidation versus NH3 selective catalytic oxidation, materials with higher CNPt-O-Ce selectively catalyzing NH3 oxidation to N2 more superior, conversely materials with lower CNPt-O-Ce performing better in CO oxidation. After activation by H2 reduction, both formed massive Pt clusters on the CeO2 surface but showed drastically distinct stability in lean-burn CO oxidation reactions. By summarizing the experimental results of high-angle annular dark-field scanning transmission electron microscopy, X-ray absorption spectroscopy, Raman spectroscopy, in situ diffuse reflectance infrared Fourier transform spectroscopy, etc., it is beyond doubt that the difference in the initial states of Pt1 due to distinct precursors indeed determine the redispersion behavior of the reduced Pt clusters on CeO2. Materials with lower CNPt-O-Ce and higher CNPt-O are more likely to form robust Pt clusters, as they are not conducive to Pt anchoring, thus restricting the reversible structural evolution occurring under lean-burn CO oxidation and reductive conditions. This approach serves as a guide for the convenient and efficient construction and exploration of robust Pt cluster catalysts.

In situ activated CoAg bimetallic catalyst for selective hydrodeoxygenation of syringol to cyclohexanol

Development of highly effective catalysts for selective hydrodeoxygenation (HDO) of syringol, a model compound of lignin, to cyclohexanol (CYHAOL) is a challenge due to the intricate molecular structure of syringol. Herein, we have synthesized an in–situ activated cobalt–silver bimetallic catalyst, CoAg/SiO2, through a simple incipient–wetness impregnation method. The catalyst without pre–reduction treatment attained a complete conversion with 93.8 mol% CYHAOL selectivity under moderate reaction conditions. Characterizations including HRTEM, XPS, XRD, NH3–TPD, and H2–TPR unanimously revealed the structure–activity relationship of the catalyst. In the reaction system, Ag promoted the in–situ reduction of Co3O4 to form a polycrystalline–structure complex (CoOx) containing oxygen vacancies. Ag also combines with Co to construct strong acid sites. The synergy of CoOx, oxygen vacancies, Ag, and acid sites demonstrates a high–efficiency HDO of syringol to CYHAOL. CoAg/SiO2 exonerates the pre–reduction treatment, simplifying the preparation and maintenance process and preventing severe sintering of the metals.