Photocatalytic selective oxidation under visible light presents a promising approach for the sustainable transformation of biomass-derived wastes. However, achieving both high conversion and excellent selectivity poses a significant challenge. In this study, two valuable trioses, glyceraldehyde and dihydroxyacetone, are produced from glycerol over Cu δ+ -decorated WO 3 photocatalyst in the presence of H 2 O 2 . The photocatalyst exhibits a remarkable five-fold increase in the conversion rate (3.81 mmol ⋅ g −1  ⋅ h −1 ) while maintaining a high selectivity towards two trioses (46.4 % to glyceraldehyde and 32.9 % to dihydroxyacetone). Through a comprehensive analysis involving X-ray photoelectron spectroscopy measurements with and without light irradiation, electron spin resonance spectroscopy, and isotopic analysis, the critical role of Cu + species has been explored as efficient hole acceptors. These species facilitate charge transfer, promoting glycerol oxidation by photoholes, followed by coupling with OH - , which are subsequently dehydrated to yield the desired glyceraldehyde and dihydroxyacetone.

The strong metal-support interaction (SMSI) is of great importance for supported metal catalysts in heterogeneous catalysis. Typically, the occurrence of SMSI is beneficial to a catalyst's stability while detrimental to its catalytic activity because the high-temperature treatment required for the construction of SMSI and the excessive encapsulation of metal nanoparticles by the support caused by SMSI often result in a significant decrease of the number of active sites. To solve this problem, this work reports a low-temperature SMSI on Pt/TiO2 induced by sodium borohydride reduction which is accompanied by a weak encapsulation degree of the Pt nanoparticles. All of the characteristics of this SMSI are consistent with those of the classical SMSI, and the key to its construction is the (weak) reduction of the support at room temperature. It was found that this low-temperature SMSI construction strategy is general, which can be expanded to other TiO2-supported metals such as Au/TiO2, and its inducing condition can be extended to other methods that can reduce the support at low temperatures, such as the decomposition of hydrazine hydrate. Owing to the low-temperature SMSI, both the catalytic activity and the reusability of the catalysts for nitrobenzene hydrogenation were significantly improved. This discovery supplies a facile strategy for the construction of SMSI under mild conditions and provides a way for the design of reusable supported catalysts with improved catalytic activity.

With the increasing production of propane from shale gas and the growing demand for propylene, propane dehydrogenation (PDH) has gained significant attention as a promising route for the on-purpose production of propylene. As a cheap yet efficient catalyst, Ni-based catalysts have attracted interest because of its ability to activate alkane. Single-atom catalysts (SACs) can maximize the metal atom utilization. Here, we demonstrate that anatase TiO2 supported Ni SAC (Ni1/A-TiO2) exhibits not only superior intrinsic activity and propylene selectivity but also much better stability than the corresponding Ni nanoparticle (NP) catalyst (NiNP/A-TiO2) in PDH reaction at 580 °C. The rate of propylene production on Ni1/A-TiO2 is about 1.96 molC3H6 gNi−1 h−1, about 65 times higher than that of NiNP/A-TiO2 sample (0.03 molC3H6 gNi−1 h−1). In combination of high-angle annular dark-field scanning transmission electron microscopy, in-situ diffuse reflectance infrared Fourier transform spectra, in-situ X-ray photoelectron spectroscopy and X-ray absorption spectroscopy characterizations, we confirm that the Ni SAC mainly contains individual Ni atom singly dispersed on the support in positive Ni (II) valence state. In addition, as a result of strong metal-support interaction (SMSI) between Ni NP and TiO2 carrier under reduced conditions, the Ni NPs sites are encapsulated by TiOx overlayer (~2 nm thick) thus display poor reaction performance.

Catalytic upgrading of bio-ethanol to 1,3-butadiene (1,3-BD, ETB) is a renewable and low-carbon technology for the bulk chemical production. Exploring robust catalysts and getting in-depth understanding of the relationship between the structure of catalytic sites and reaction selectivity are of great significance for ETB process applications. In this study, we constructed a robust Cu-Zr/SiO2 catalyst by an ammonia evaporation and post-impregnation method. Over the optimal 2%Cu-8%Zr/SiO2 catalyst, superior performance of 69.6% 1,3-BD selectivity and 71.2% ethanol conversion were obtained. Systematic characterizations revealed that three types of Cu-Zr-Si active sites were probably constructed on the Cu-8%Zr/SiO2 catalysts as varying the Cu loadings from 0.5 to 20%, affording greatly different activity and selectivity in the ETB process. The 1,3-BD productivity over the (SiO)2(CuO)Zr-OH sites was 8.2 and 77.2 times higher than that of (CuO)2-Zr-(OSi)2 and Cu-(O)2-Zr-(OSi)2 sites, respectively, attributed to the high activities and good balance among the reactions of dehydrogenation, aldol condensation, and MPVO reduction.

Supported metal nanoclusters (NCs) are regarded as the next generation of catalyst that bridge the nanocatalyst and single-atom catalyst. However, feasible fabrication of thermally stable NCs has remained a daunting challenge. In this paper, the first part of an extended work, we report a simple route to fabricate Pt NCs in size of around 1 nm through redispersion of Pt nanoparticles (NPs) or commercial PtO2 by a calcination treatment. Combining control experiments and detailed DFT simulation, the whole redispersion process was described and evidenced to proceed via a gas-phase trapping way: Under promotion of oxygen atmosphere and high temperature, volatile oxidized Pt monomers were firstly generated and then trapped by surface defects, forming special sites that preferentially induce the growth of clusters on them. The growing clusters have both size- and temperature-dependent stability, resulting a most stable size distribution of around 1 nm when fabricated at 550 °C. This work provides a feasible top-down strategy to fabricate highly dispersed metal clusters.

Noble metals such as iridium with high Tammann temperature are inclined to sintering resistance and may be promising in the high-temperature dry reforming of methane (DRM) process, yet the low atom utilization remains intractable. Herein, we synthesized Ir/TiO2 catalysts via the conventional incipient wetness impregnation method and further downsized the Ir species from a nanoparticulate to a single-atom scale by gradually decreasing Ir loadings from 1.0 wt.% to 0.01 wt.%. With the advantage of single atoms for maximized atom utilization, Ir single atoms were employed to enhance atom utilization in the DRM process. Various characterizations, such as aberration-corrected high-angle annular dark-field scanning transmission electron microscopy, CO adsorbed in situ diffuse reflectance infrared Fourier transform spectra and X-ray absorption spectra demonstrated the existence of Ir single atoms in 0.01% and 0.05% Ir/TiO2. During the DRM process, Ir single-atom catalysts exhibited a better specific reaction rate of as high as 697.71 molCH4·gIr-1·h-1 at 750 °C compared with that over Ir nanoparticles of mere 447.12 molCH4·gIr-1·h-1, which unambiguously showed the remarkable Ir atom utilization over Ir single atoms. Besides, the Ir single-atom catalysts also exhibited excellent stability during the DRM process for 50 h and revealed outstanding anti-coking and good sintering-resistance properties examined by the thermal gravimetric analysis-mass spectrometer and Raman spectroscopy. The strategy of employing Ir single atoms for the maximum atom utilization in the high-temperature reaction process can pave the way for better exploitation of noble metals in other industrial reaction processes.

A Pt–Fe bimetallic catalyst is developed to produce 1,2-pentanediol from furfural under mild conditions of 140 °C and 0.1 MPa H 2 , affording by far the highest production rate.

Controlling the precise placement of active metals on supports is highly desirable yet challenging, which governs both the reaction pathway and the ultimate outcomes of catalytic reactions. Herein, the Cu species are positioned to the Lewis acidic sites created by the ultrahigh-temperature calcination of TiO2, where the atomic structures of the Lewis acids are identified as five-coordinated Ti4+ cations bound to three-coordinated O2- anions (L-beta sites) by in situ characterizations. Owing to the robust chemical affinity, CuOx manifests itself as a nanopatch. The Cu/TiO2 catalyst without any modifications exhibits a propylene oxide (PO) formation rate of 44 mmol g(Cu)(-1) h(-1) for direct epoxidation of propylene using molecular oxygen (DEP). The PO yield on Cu/TiO2 can be efficiently correlated with the quantity of the decreased Lewis acids, which demonstrates that the intimated interaction between the Cu species and Lewis acids should be responsible for PO production. Furthermore, density functional theory calculations suggest that Cu+ in the Ti-O-Cu interface formed at the L-beta sites is the active site of the DEP reaction, with the aid of the adjacent Cu atom. This study provides a Cu-based catalyst for the DEP reaction.

Ru-based catalysts feature an intrinsic activity toward NH3 decomposition, while their catalytic mechanism associated with the interface with support remains elusive. Herein, with the interfacial regulation of Ru catalysts by TiO2 via strong metal-support interactions (SMSI), i.e., Ru/TiO2, an enhanced activity of NH3 decomposition can be realized with a turnover frequency of hydrogen production 2-fold higher than that on Ru/SiO2. With characterizations and density functional theory calculations, the newly generated Ru/TiO2-x interface with the electron-rich Ru sites was proven to not only facilitate the adsorption of ammonia and its N-H bond cleavage but also promote the associative desorption of N* species. Moreover, the poisoning kinetics of hydrogen during reactions can also be alleviated due to the associative desorption of H* occurring primarily on the residual Ru surface. This work demonstrates that interfacial regulation provides an efficient strategy for the catalytic activity modulation of Ru-based catalysts especially in NH3 decomposition.

Strong metal-support interaction (SMSI) is an important concept in heterogeneous catalysis that has a profound effect on the structure and activity of the supported metal catalyst. However, the catalyst with an uncontrolled SMSI state significantly prevents the accessibility of metal surface to reactants by encapsulation process which inevitably limits their practical application. Herein, we demonstrate that under the reaction condition of dry reforming of methane (DRM), the occurrence of SMSI (CO2-SMSI) can be operando induced between Rh and CeO2 which significantly improves the catalytic activity in DRM reaction. Detailed study has revealed that the formation of suitable Rhδ+/Rh0 species in CO2-SMSI is critical in improving CH4 activation, while the presence of permeable encapsulation layer is helpful to provide more active sites. This discovery provides a new approach to overcome the limitation of classical SMSI catalyst in DRM reaction.

The supported Pd catalyst has been a benchmark for methane elimination. However, the active structures have been long under debate. Here, by the aberration-corrected high angle annular dark field scanning transmission electron microscopy, operando X-ray absorption spectroscopy and quasi in situ X-ray photoelectron spectroscopy, we revealed the two-dimensional metallic Pd bumps on the PdO surface (litchi-like structure) generated by the redox atmosphere under the lean condition as a highly active structure of the Pd/Al 2 O 3 catalyst. The substantially increased Pd/PdO interfaces boost the methane combustion activity higher than the similar catalysts reported previously, and remarkably enhance the reaction rate by 15.5 and 10.7 times that of pure PdO or metallic Pd counterpart under lean condition at 300 degrees C, respectively. Density-functional theory calculations confirm the synergistic C-C bond activation of methane on the Pd/PdO interfaces. Our work provides new insight into the traditional understanding of the chemical state and particle size effects of the industrial Pd catalysts for methane oxidation. (c) 2024, Dalian Institute of Chemical Physics, Chinese Academy of Sciences.

The influence of water on catalytic methane combustion reaction was studied over Pd/CeO2 catalysts with different Pd loadings, prepared by an industrial-friendly impregnation method using 800 degrees C-calcined CeO2 as support. Despite having a similar structure and uniform particle sizes, the catalyst loaded with 0.4wt% of Pd showed significantly lower Pd mass-specific activity and worse water resistance than the catalysts loaded with 2.0wt% and 4.0wt% of Pd. Characterization results by the temperature-programmed reduction of H2, temperature-programmed surface reaction of CH4, in situ diffuse reflectance infrared Fourier transform spectroscopy using CO as the probe molecular, and X-ray photoelectron spectroscopy suggested the interaction between the Pd and CeO2 of the catalysts could be tuned by controlling the loading of Pd, which could further affect their catalytic behaviors with/without water. The suppression of oxygen spillover between Pd and CeO2 was recognized as the reason for water inhibition of the Pd/CeO2 catalyst loaded with 0.4wt% of Pd. The reversible coverage was dominated for the water effect over the Pd/CeO2 catalysts loaded with 2.0wt% and 4.0wt% of Pd, which could guarantee the recovery of their catalytic activity for methane combustion after the water in the reaction gas being turned off. This work provides deep insight into the loading effect, which can provide references for synthesizing catalysts for industrial applications.

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.

Water gas shift (WGS) reaction is an important process to remove CO contaminant in industrial hydrogen resources. The efficient catalyst that can work at low temperature is keenly desired to achieve high CO conversion from the viewpoint of thermodynamic equilibrium. Here, we develop a noble-metal-free catalyst of MoC nanorod (MoC NR) with the dominant (2 0 0) facet for the low-temperature WGS reaction. It exhibits a high performance with similar to 100 % CO conversion at 175 degrees C, better than conventional MoC with the dominant (1 1 1) facet or the commercial Cu-based catalyst. Moreover, it shows rather better stability due to the presence of the dominant (2 0 0) facet. Various characterizations demonstrate that this facet facilitates MoC NR possessing higher removal capability of surface oxygen species to enhance the stability and lower activation energy to endow higher performance compared with conventional MoC. This study provides important implications for the rational design of cost-effective catalysts for the low-temperature WGS reaction.

Besides the Pd/Al2O3, the Pd-CeO2 catalysts are the indispensable and promising candidates for methane combustion. The Pd-CeO2 composites with intimate interaction realized by elaborate methods are regarded as the most active formulations. However, more facile and cost-efficient methods are needed for industrial application. Herein, the Pd was incorporated into the lattice of the Mn-doped CeO2 by an optimized co-precipitation method to synthesize the PdCeMnO-CP catalyst. The PdCeMnO-CP showed much higher catalytic activity with the T 10 decreased by 70 degrees C than that of the Pd/CeMnO-Imp prepared with impregnation. The partial exsolution of the initially doped Pd species and the lowered valence of Pd (from Pd4+ to Pd delta+, delta: 2 similar to 4) during the reaction were confirmed by the low-temperature CO-DRIFTs, CO-pulse chemisorption, XRD and XPS, which were responsible for the activity enhancement. The undercoordinated Ce4+ species were generated during the reaction, thus improving the mobility of the lattice oxygen which is vital for the methane combustion following the MvK mechanism. The PdCeMnO-CP also showed higher activity for the complex methane-containing three-way catalytic reactions than the Pd/CeMnO-Imp, demonstrating its potential for industrial application.

Copper catalysts have been extensively investigated for the dehydrogenation of ethanol to acetaldehyde. However, identifying the essential active sites for this reaction is difficult because of the complex coordination structure and variable valences of the Cu species during the reaction. The stability of the Cu catalysts in the reaction also needs to be substantially improved. In this study, Cu-MFI, a well-defined Cu-based Lewis acid catalyst, was prepared using a post-acid treatment method for ethanol dehydrogenation. Different from the widely reported Cu+ and Cu0 species accounting for the activity of Cu catalysts, conditional experiments and in situ characterizations revealed that the highly dispersed Cuδ+ (1 < δ < 2) species on the MFI support are the essential active sites for ethanol dehydrogenation. Due to the strong interaction between Cu and silica via the Cu–O–Si linkage, the Cuδ+ species were very stable in the reaction and played the role of a Lewis acid catalyst in promoting ethanol activation and dehydrogenation. Over the optimal catalyst 5%Cu-MFI-deCu, 95% selectivity of acetaldehyde and approximately 87% ethanol conversion were obtained at 250 °C and a weight hourly space velocity of 0.64 h−1 in 120 h time on stream.

The sustainable production of value-added N-heterocycles from available biomass allows to reduce the reliance on fossil resources and creates possibilities for economically and ecologically improved synthesis of fine and bulk chemicals. Herein, we present a unique Ru1CoNP/HAP surface single-atom alloy (SSAA) catalyst, which enables a new type of transformation from the bio-based platform chemical furfural to give N-heterocyclic piperidine. In the presence of NH3 and H2, the desired product is formed under mild conditions with a yield up to 93%. Kinetic studies show that the formation of piperidine proceeds via a series of reaction steps. Initially, in this cascade process, furfural amination to furfurylamine takes place, followed by hydrogenation to tetrahydrofurfurylamine (THFAM) and then ring rearrangement to piperidine. DFT calculations suggest that the Ru1CoNP SSAA structure facilitates the direct ring opening of THFAM resulting in 5-amino-1-pentanol which is quickly converted to piperidine. The value of the presented catalytic strategy is highlighted by the synthesis of an actual drug, alkylated piperidines, and pyridine.

Catalyticsemihydrogenation of acetylene is crucial for ethylenepurification but still faces a grand challenge in circumventing deephydrogenation and oligomerization so far, especially for the cost-effectivecatalysts. Herein, two Ni-based intermetallic nanocatalysts with differentatomic arrangements were subtly constructed via controlling the reductiontemperature of ZnO-supported NiO particles. The one reduced at 400 & DEG;C is L1(2)-type intermetallic Ni3Zn withseparated Ni-3 trimers (denoted as Ni/ZnO-R400 or Ni3Zn/ZnO); another reduced at 600 & DEG;C is L1(0)-typeintermetallic NiZn with the homogeneous Ni single atoms completelyisolated by Zn atoms (denoted as Ni/ZnO-R600 or NiZn/ZnO). The systematicalevaluations validate NiZn/ZnO as an outstanding noble metal-free catalystfor acetylene semihydrogenation, showing a significantly enhancedselectivity toward ethylene relative to Ni3Zn/ZnO (87.5vs -275.4% at 200 & DEG;C) through suppressing not only theunselective hydrogenation to ethane but also carbon deposition. Accordingto catalytic evaluations with or without ethylene, microcalorimetry,and density functional theory calculations, the superior selectivityof NiZn/ZnO stems from the noncompetitive adsorption between the moderately & sigma;-bonded acetylene over two neighboring Ni single atoms andweakly & pi;-bonded ethylene on Ni single-atom sites due to itsunique Ni-Zn-Ni ensemble. NiZn/ZnOis validated as an excellent noble metal-free catalystfor the semihydrogenation of acetylene due to the noncompetitive adsorptionbetween the moderately bonded acetylene and weakly bonded ethyleneover its unique Ni-Zn-Ni ensemble.

The PtSn/Al2O3 is a prototypical industrial catalyst for propane dehydrogenation (PDH). However, the local structures of the active sites are still inconclusive under the operation conditions. Herein, the evolutions of the Pt-Sn active centers supported on nano-Al2O3 are definitely discerned at the atomic level during PDH reaction. By combining complementary in situ characterizations and theoretical calculations, we demonstrate that a highly productive Sn1Pt single-atom alloy (47.6 molC3H6 gPt–1 h–1) forms after the reduction, and thereby self-assembles to the Pt3Sn intermetallic compound during the reaction, which exhibits a rather stable performance (kd-10~40h: 0.0026 h–1). Intriguingly, the results of in situ diffuse reflectance infrared Fourier-transform spectroscopy further corroborate that the adjacent Pt atoms with terrace sites aggravating the coke deposition can be circumvented through this single-atom alloy mediated reconstruction. Our findings depict an unprecedented evolution process of the active sites of the PtSn/Al2O3, and afford an effectual nanostructure engineering pathway for stable PDH catalysts.

Sintering of Ni-based catalysts and the following detrimental carbon depositions are still the major challenges to be overcame in the high-temperature dry reforming of methane (DRM) process. Herein, we for the first time induced classical strong metal-support interaction (SMSI) between Ni nanoparticles and vanadate substituted hydroxyapatite (VAP) under H2 atmosphere at as low as 300 & DEG;C (Ni/VAP-H300) to hinder the sintering of Ni nanoparticles during DRM process. TEM and element mapping analysis unambiguously exhibit the configuration of Ni nanoparticles encaged within the partially reduced VAP overlayer and subsequent linear-scan EDS investigations on the Ni/VAP-H300 at the reaction time of 25 h, 100 h and 260 h further elucidate the relatively intact VAP overlayer during the reaction, thus the CH4 conversion merely decreasing from 92 % to 79 % after stability test for 260 h. In contrast, Ni nanoparticles supported on conventional hydroxyapatite (Ni/HAP) give inferior stability, CH4 conversion drastically decreasing from 91 % to 42 % only after 25 h due to the absence of SMSI. Moreover, there also occurs electron-transfer between Ni nanoparticles and the adjacent VAP overlayer, thus showing higher CH4 decomposition activity compared with Ni/HAP. Combined with the excellent CO2activating property of VAP support identified by CO2-TPD and gasification tests of the deposited carbon, the asobtained Ni/VAP demonstrates outstanding initial activity and decent stability during DRM, which broadens the horizons of improving catalytic stability even under harsh reaction conditions by precisely exploiting the SMSI.