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Metal confinement catalyst MoS2/Pt@TD-6%Ti (TD, TS-1/Dendritic mesoporous silica nanoparticles composite) in dendritic hierarchical pore structures was synthesized and showed excellent sulfur-resistance performance and stabilities in catalytic hydrodesulfurization reactions of probe sulfide molecules. The MoS2/Pt@TD-6%Ti catalyst combines the concepts of Pt-confinement effect and hydrogen spillover of Pt noble metal. The modified micropores of Mo/Pt@TD-6%Ti only allow the migration and dissociation of small H2 molecules (0.289 nm), and effectively keep the sulfur-containing compounds (e.g. H2S, 0.362 nm) outside. Thus, the MoS2/Pt@TD-6%Ti catalyst exhibits higher DBT and 4,6-DMDBT HDS activities because of the synergistic effect of the strong H2 dissociation ability of Pt and desulfurization ability of MoS2 with a lower catalyst cost. This new concept combining H2 dissociation performance of noble metal catalyst with the desulfurization ability of transition metal sulfide MoS2 can protect the noble metal catalyst avoiding deactivation and poison, and finally guarantee the higher activities for DBT and 4,6-DMDBT HDS.

The morphologies and the electron property of catalysts play the very important roles in the hydrogenation and dehydrogenation of liquid organic hydrogen carriers (LOHCs) such as dibenzyltoluene (DBT). The different morphologies and pore structures of γ-Al2O3 and MoxC doped γ-Al2O3 were synthesized as the supports for Pt catalysts. After analyzing of various characterizations and catalytic testing, it was found that the large surface area and the mesoporous structure of catalysts are beneficial to both DBT hydrogenation and perhydro-dibenzyltoluene (H18-DBT) dehydrogenation. The doping of MoxC promoted the formation of the smaller Pt nanoparticles and increased Pt dispersion. The forming Pt–Mo structure is beneficial to hydrogen spillover which suppress the formation of by-product. The high Pt dispersion of 0.1 wt% MoxC doped Pt/Al2O3 catalyst plays the positive roles in increasing H18-DBT dehydrogenation activity.

On-site produced hydrogen from ammonia decomposition can directly fuel solid oxide fuel cells (SOFCs) for power generation. The key issue in ammonia decomposition is to improve the activity and stability of the reaction at low temperatures. In this study, proton-conducting oxides, Ba(Zr,Y) O3-δ (BZY), were investigated as potential support materials to load Ni metal by a one-step impregnation method. The influence of Ni loading, Ba loading, and synthesis temperature, of Ni/BZY catalysts on the catalytic activity for ammonia decomposition were investigated. The Ni/BZY catalyst with Ba loading of 20 wt%, Ni loading of 30 wt%, and synthesized at 900 °C attained the highest ammonia conversion of 100% at 600 °C. The kinetics analysis revealed that for Ni/BZY catalyst, the hydrogen poisoning effect for ammonia decomposition was significantly suppressed. The reaction order of hydrogen for the optimized Ni/BZY catalyst was estimated as low as −0.07, which is the lowest to the best of our knowledge, resulting in the improvement in the activity. H2 temperature programmed reduction and desorption analysis results suggested that a strong interaction between Ni and BZY support as well as the hydrogen storage capability of the proton-conducting support might be responsible for the promotion of ammonia decomposition on Ni/BZY. Based on the experimental data, a mechanism of hydrogen spillover from Ni to BZY support is proposed.

Identifying optimal Ru size in NH3 synthesis can improve reaction activity and maximize the utilization of Ru to reduce catalyst cost. However, previous researches are focused on large Ru particle size (≥ 2 nm) while that below 2 nm in NH3 synthesis is unclear. Here we synthesized a series of Rux/BaCeO3 with different Ru sizes (x=1.1–3.0 nm) through size-controlled Ru colloid. With the decrease of Ru size, NH3 synthesis rate over Ru1.1/BaCeO3 increases to 19.4 mmol gcat−1 h−1 at 400°C and 1 MPa, which is 5.7 times that of Ru3.0/BaCeO3 and superior to most of Ru-based catalysts previously reported. It reveals that the reduction of Ru size enhances the generation of Ce3+ and oxygen vacancies in BaCeO3, which can donate electron to Ru centers and promote N2 dissociation. Moreover, the small Ru size enhances hydrogen spillover from Ru to BaCeO3 to alleviate hydrogen poisoning, resulting in efficient NH3 synthesis.

Sulfur poisoning of noble metal catalysts has been a major challenge for decades. This work demonstrates the superior sulfur tolerance of a hybrid zeolite-supported Pd catalyst for hydrogenation of tetralin containing benzothiophene. The hybrid catalyst consists of Pd supported on a large-pore acidic zeolite Y (Pd/HY) and a small-pore zeolite A without (Pd/HA) or with surface metal passivation by chemical vapor deposition of SiO2 (SiO2-Pd/HA) and with potassium ion exchange (SiO2-Pd/KA). Pd/HY is very active for tetralin hydrogenation but quickly deactivates after exposure to benzothiophene at high concentration of 100 ppm sulfur. The SiO2-coated Pd/HA shows no activity for tetralin hydrogenation, but continues to activate H2 and serve as a source of hydrogen spillover from Pd/HA since these metal sites are protected from thiophenic sulfur due to size-selective exclusion. Adding K ion-exchanged and SiO2-coated catalyst SiO2 -Pd/KA to Pd/HY is even more effective for enhancing sulfur tolerance, both for tetralin hydrogenation and for isomerization of cis-decalin to trans-decalin in the presence of benzothiophene. The turnover frequencies (TOF) of all the catalysts are similar at the exposed sulfur/Pd atomic ratio of around 0.5. With further increase in sulfur/Pd ratio, rapid decline in TOF was observed on Pd/HY, but SiO2-Pd/KA + Pd/HY hybrid catalyst shows a significantly higher TOF than that over Pd/HY, even though SiO2-Pd/KA or SiO2-Pd/HA alone shows no TOF for tetralin hydrogenation. Even after high-dose poisoning at 400 ppm sulfur, the SiO2-Pd/KA + Pd/HY hybrid recovered activity more quickly than SiO2-Pd/HA + Pd/HY, while the latter in turn is much better than Pd/HY alone. These results point to the higher activity for hydrogen spillover from SiO2-Pd/KA where Pd metal sites are protected from not only thiophenic sulfur but also inorganic sulfur H2S by shape-selective exclusion. The present work further establishes the validity of shape-selective exclusion and hydrogen spillover in the design concept proposed for a sulfur-tolerant bimodal acidic zeolite-supported metal catalyst for hydrogenation of naphthalene [C.S. Song, Chemtech, 29 (1999) 26–30], and refines the design concept further for limiting the size of small pore in hybrid catalysts to ∼ 3 A for restricting access of H2S but allowing entrance of H2. This refined design concept is applicable to other supported monometallic and bimetallic catalysts.

Here we exquisitely fabricated Cu/ZrO2-dp catalysts with plentiful Cu-ZrO2 interfaces by depositing amorphous ZrO2 onto Cu nanoparticles for the hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL). With the created plentiful Cu-ZrO2 interfaces, the optimal catalyst 3Cu/ZrO2-dp exhibited exceptional catalytic performance under mild reaction conditions, and achieved the highest GVL mass productivity of 266.0 mmol GVL·h−1·g−1 Cu, which was 12.5 and 2.3 times of Cu/ZrO2 catalysts with equivalent Cu loadings prepared by traditional impregnation (3Cu/ZrO2-im) or co-precipitation (3Cu/ZrO2-cp). As far as we know, this GVL mass productivity stood at the highest level compared with those obtained using non-noble metal catalysts under similar reaction conditions. By systematic investigation with multiple characterizations, density functional theory (DFT) calculations, and kinetic studies, it was found that interfacial active centers were created at Cu-ZrO2 interfaces, which contained oxygen vacancies (Ov), negatively charged Cuδ− and partially reduced Zr3+. The Ov favored the adsorption and activation of LA via its ketone group, while negatively charged Cuδ− was able to enhance heterolysis of H2, which resulted in the formation of H+-Cuδ− and Zr3+-H− active species via hydrogen spillover. Also, plentiful acid sites, which derived from coordinatively unsaturated and defective Zr species, generated at Cu-ZrO2 interfaces. With the cooperation of interfacial active centers (Cuδ−-Ov-Zr3+) and acid sites, the fabricated 3Cu/ZrO2-dp with plentiful Cu-ZrO2 interfaces achieved excellent catalytic performance for the hydrogenation of LA to GVL. Hence, the synergistic catalysis of Cu-ZrO2 interfaces provided an effective strategy for designing catalysts with a satisfactory performance for the hydrogenation of LA, which also can be expanded to other hydrodeoxygenation reactions.

Side reactions competing with propane dehydrogenation were studied on K-PtSn/Al2O3 and SnOx/SiO2 catalysts. The results showed that hydrogenolysis, hydrogenation, deep dehydrogenation, and coke formation occurred more pronouncedly on K-PtSn/Al2O3, contrasting with the catalytic cracking result. Because of the higher total acidity on SnOx/SiO2, measured by NH3-TPD, more catalytic cracking occurred on this catalyst. However, SnOx/SiO2 showed a lower coke deposition, although the acid site can promote the coke formation. This contrast was not due to the spillover effect, which can suppress coke formation on the acid site. Essentially, the propylene hydrogenation, H2-TPD, and FTIR results demonstrate that SnOx/SiO2 had a lower hydrogen spillover than that of K-PtSn/Al2O3. On the other hand, TPO results from propylene dehydrogenation and coke formation of propadiene illustrate that the key of distinguished SnOx/SiO2 catalyst stability was owing to a low ability of coke precursor generation.

A new variety of CdS/NiO core-shell p-n heterojunction is synthesized by in-situ chemically depositing NiO shell on single-crystal CdS nanorods for the first time. With this method, the range of NiO shell thickness can be accurately controlled within a few nanometers. The optimized CdS/NiO sample (CSN0.5) with a NiO shell layer of 1.5 nm exhibits a highly efficient photocatalytic H2 evolution rate of 731.7 μmol/h (corresponding to 243.9 mmol/g/h) without using co-catalyst, which is among the highest value of all the CdS-based photocatalysts. The apparent quantum efficiency (AQE) of CSN0.5 at 365 nm wavelength reaches 28.19%. The remarkably enhanced photocatalytic performance can be attributed to a hydrogen spillover effect induced by ascorbic acid in CdS/NiO, which promotes the transmission of adsorbed H* from hydrogen-rich NiO (electron-poor region) to hydrogen-poor CdS (electron-rich region) where the adsorbed H* reacts in time with the photogenerated electron to produce H2, facilitating the H2 evolution reaction. This work provides a method to promote the photocatalytic H2 evolution reaction by using hydrogen spillover effect.

As a hydrogen storage material, palladium nanoparticle decorated nitrogen doped graphene (Pd/N-rGO) has drawn much attention owing to its high absorption capacity at moderate conditions. However, its hydrogen absorption-desorption cycle performance, which is essential for their practical application, has been rarely studied. In this paper, a simple and convenient high temperature thermal reduction method was used to synthesize nitrogen-doped graphene decorated with Pd nanoparticles (Pd/N-rGO). Taken it as a representative, the hydrogen absorption-desorption cycle performance of Pd/N-rGO was investigated. The results showed that after three cycles the hydrogen storage capacity dropped from 2.9 ​wt% to 0.8 ​wt% at 25 ​°C and 4 ​MPa pressure. It was found that the palladium nanoparticles shed from Pd/N-RGO sheet after cycle performance test, and then agglomerated. These phenomena will weaken the hydrogen spillover effect, leading to the decrease of hydrogen storage capacity. Meanwhile, decreased defects reduce the hydrogen absorption sites, which will thus deteriorate the hydrogen storage capacity.

Currently, the highly efficient conversion of biomass resources into highly valuable chemicals and biofuels is one of the most prospective approaches to reduce greenhouse gases emission and environmental pollution caused by excess consumption of fossil fuels. Herein, three-dimensional pompon-like well-defined RuCo particles with tunable crystallographic structures and surface atomically dispersed Ru atoms were constructed and intensively investigated as support-free metal catalysts in the hydrodeoxygenation (HDO) of lignin-derived guaiacol. It was demonstrated that the 300 °C-reduced RuCo sample possessed the hexagonal close-packed (hcp ) crystallographic structure with surface abundant atomically dispersed Ru atoms, whereas 600 °C-reduced RuCo sample presented the face-centered cubic phase with lower surface Ru concentration. The as-fabricated RuCo-300 sample showed excellent catalytic HDO activity with a high cyclohexane yield of 85.3%. Comprehensive structural characterizations unveiled that the introduction of atomically dispersed Ru atoms into the RuCo-300 favored the formation of abundant surface Ru-Co sites, as well as electron-rich Ru 0, and such-constructed Ru-Co sites were highly beneficial to the hydrogen dissociation on single Ru0 atoms and the further hydrogen spillover to adjacent Co0 atoms to promote the HDO process. Moreover, density functional theory (DFT) calculations revealed that the hcp structure of RuCo catalysts benefited the adsorption of guaiacol. The unique pompon-like microstructure of RuCo catalysts was conducive to the exposure of active sites and provided more open channels for the easy diffusion of reactants and products. Over the RuCo-300 catalyst, the guaiacol HDO could proceed rapidly via an initial demethoxylation reaction. The present Ru-Co synergetic catalysis in the structure of RuCo catalysts would provide a new strategy for constructing robust heterogeneous bimetal catalysts applied in practical HDO processes of a variety of lignin-derived phenolic compounds.

In this study, the hydrogen storage capacity of purified multiwalled carbon nanotubes (MWCNTs) was enhanced from 13- to 15-fold at a temperature of 298 K and pressure of 2.0 MPa, upon incorporation of 1.57–1.88 wt% of ultrafine Ti nanoparticles. The effect of a hydrogen spillover Ti catalyst on MWCNTs prepared using the sputtering method was investigated. A comparison between the hydrogen uptake by MWCNTs sputtered with Ti for 3000 s and that for 6000 s was also performed using the Sievert's volumetric apparatus. The significant enhancement in hydrogen uptake was attributed to the interfacial diffusion of hydrogen from Ti to the MWCNTs. The re-adsorption of hydrogen on the pristine MWCNTs and Ti-decorated MWCNTs dehydrogenated at 200 °C indicated that the samples did not compromise their reversible hydrogen uptake during the hydrogenation–dehydrogenation cycles. It was also found that longer exposure of Ti to the MWCNTs during sputtering improved the hydrogen storage capacity. This improvement could be attributed to the presence of a higher amount of Ti deposited on the MWCNTs, as indicated by thermogravimetric analysis study.

The Platinum (Pt)-based catalysts exhibit excellent catalytic performance for the hydrogen evolution reaction (HER) while suffering from poor stability due to the weak interaction between the carbon support and Pt. Herein, a molybdenum-doped titanium dioxide (Ti0.9Mo0.1O2) supported low-Pt electrocatalyst with stronger interaction between catalyst and support is applied to tune the electrocatalytic performance of Pt. The Ti0.9Mo0.1O2 support can not only tolerate the corrosion environment in the catalytic system, but also generate strong metal-support interaction (SMSI) between the oxide and catalyst. A facile solvothermal method is used to prepare Ti0.9Mo0.1O2 as support to anchor Pt nanoparticles. The 5% Pt supported on Ti0.9Mo0.1O2 catalyst exhibits 4.4-fold mass activity (MA) at an overpotential of 50 mV and higher stability than 20% Pt/C with only 1/4 Pt loading. The SMSI between the Ti0.9Mo0.1O2 and Pt prevents the Pt aggregation to achieve excellent stability, and hydrogen spillover effect in the interface between Pt and support benefits the hydrogen production process. This work presents a novel sight for the fabrication and design of oxide supported catalysts in various catalytic system by reasonably employing support effect.

The extent of hydrogen spillover on two different Pd-based catalysts supported on mesoporous SBA-15 and MCM-41 is quantitatively predicted using a crystallite-scale model, which considers the effect of size and location of crystallites, metal-support interfacial contact, and diffusivity of the adsorbed species on the support surface. The developed model, in combination with a fixed-bed reactor model predicts that in the absence of any reductant in the feed, the NO conversion is higher ( = 37 %) on the SBA-15 supported catalyst as compared to 25 % on MCM-41, which is consistent with the reported data in the literature. The difference in the catalytic activity is ascribed to the different spillover rates of hydrogen on SBA-15 and MCM-41, which is further correlated to the fraction of Pd crystallites present in the support channels. The model is also used to study the effect of cycle time, H2 concentration, Pd dispersion, and Pd loading on NO reduction under cyclic conditions. Consistent with the literature findings, the model predicts that the Pd surface area and the metal-support interfacial contact increase with an increase in the Pd loading and dispersion, which result in higher spillover and hence increase the NO conversion. Even though the present model has been developed for the H2-SCR system, it can also be extended to other catalytic systems where spillover effects are significant.

Metallic oxide based catalysts have received much attention in CO2 hydrogenation to methanol because of their high methanol selectivity and long-term stability. But the relatively weak hydrogenation ability leads to low methanol activity. Here, we introduce a small amount of Cu (molar fraction

The tungsten oxide nanorods loaded with ruthenium nanoparticles (Ru-WO3) nanocomposite were synthesized by hydrothermal method and impregnation method. The properties of Ru-WO3 catalysts were characterized by various methods, such as BET, XRD, SEM, TEM, EDS and XPS. The results show that hydrogen spillover occurs on the surface of WO3 and the catalytic activity of Ru-WO3 in hydrogenation of cyclohexene increases with the increase of reaction time. Subsequently, the Ru-WO3 catalysts was used to hydrogenate N-propylcarbazole (NPCZ). Compare with commercial 0.5 wt% Ru–Al2O3 catalyst, Ru-WO3 can realize the rapid hydrogen uptake of NPCZ at a lower metal loading (0.34 wt%) and lower temperature (150 °C), which is attributed to the increase of reactive sites caused by hydrogen spillover.

The effect of hydrogen introduction on Lewis acid transformation to Bronsted acid was investigated over the WOx catalysts supported on different supports (HY-15, HY-500, MCM-22, SiO2, and Al2O3). The Lewis acid transformation on the catalysts was investigated by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of adsorbed NH3 at 100 °C under atmospheric pressure for 130 min. According to the results of in situ DRIFTS, ammonia migration from Lewis acid sites to Bronsted acid sites occurred over the WOx catalysts supported on all different supports. It is proposed that the partial reduction of WOx occurred under the hydrogen atmosphere, resulting in the generation of oxygen vacancies sites. The generated oxygen vacancies of the supported WOx catalysts were found to play an important role for activating the hydrogen spillover, leading to Lewis acid transformation to Bronsted acid. It was suggested that the selected support is the crucial factor for Lewis acid transformation performances. The results from our experiments showed that the weak interaction between WOx and support led to the easy reduction of W species, which promoted the generation of oxygen vacancies sites. The large amount of oxygen vacancies leads to high Lewis acid transformation. Moreover, the influence of different supports was discussed and investigated by several analytical techniques such as H2-TPD, H2-TPR, O2-TPD, UV–vis, XRD, XPS, and TEM-EDS techniques.

An In2O3 supported nickel catalyst has been prepared by wet chemical reduction with sodium borohydride (NaBH4) as a reducing agent for selective hydrogenation of carbon dioxide to methanol. Highly dispersed Ni species with intense Ni-In2O3 interaction and enhanced oxygen vacancies have been achieved. The highly dispersed Ni species serve as the active sites for hydrogen activation and hydrogen spillover. Abundant H adatoms are thereby generated for the oxygen vacancy creation on the In2O3 surface. The enhanced surface oxygen vacancies further lead to improved CO2 conversion. As a result, an effective synergy between the active Ni sites and surface oxygen vacancies on In2O3 causes a superior catalytic performance for CO2 hydrogenation with high methanol selectivity. Carbon monoxide is the only by product detected. The formation of methane can be ignored. When the reaction temperature is lower than 225 °C, the selectivity of methanol is 100%. It is higher than 64% at the temperature range between 225 °C and 275 °C. The methanol selectivity is still higher than 54% at 300 °C with a CO2 conversion of 18.47% and a methanol yield of 0.55 gMeOH gcat−1 h−1 (at 5 MPa). The activity of Ni/In2O3 is higher than most of the reported In2O3-based catalysts.

Summary Ideal heterogeneous metal hydrogenation catalysts are featured by simultaneously high activity, selectivity, and stability. Herein, we report a general yet powerful strategy to design and fabricate dual-active-sites Co@C core-shell nanoparticle for boosting selective hydrogenation of various N-heteroarenes. It can break the limitation of scaling relation on traditional metal surfaces, and thus afford unprecedentedly high selectivity, activity, and stability. Combining kinetics analysis and DFT calculations with multiple techniques directly unveil that the critical porous carbon shell with a pore size of 0.53 nm not only allows H2 diffusion to Co sites for activation and blocks accessibility of N-heteroarenes but also catalyzes hydrogenation of N-heteroarenes via hydrogen spillover from Co sites. In addition, the presence of surface/subsurface carbon at the Co sites shows high anti-sulfur poisoning and anti-oxidant capability. This work is valuable for guiding the design and manipulation of cost-effective and robust hydrogenation catalysts.

Ni–La2O3 cermet hydrogen electrode having almost no ionic conductivity still exhibits excellent electrochemical performance owing to the hydrogen spillover process from high hydrogen adsorption capability on the La2O3 surface. In this work, we develop Ni–La2O3 cermet hydrogen electrode originating from the in-situ decomposition of the La2NiO4+δ(LNO) oxide, and then perform the electrochemical properties for quasi-symmetrical solid oxide fuel cells (Q-SSOFCs), which own YSZ electrolyte support wrapped GDC barrier layer. The area specific resistance (ASR) of LNO air electrode increases from 2.09 to 7.41 Ω cm2, with the temperature of decreasing from 800 to 600 °C. The electrochemical performances of Q-SSOFCs with Ni–La2O3 cermet hydrogen electrode and LNO air electrode are characterized, and the values of the peak power density and the electrode polarization resistance (Rp) of the symmetrical electrodes measured at 800 °C are 245.18 mW cm−2 and 0.61 Ω cm2. These results indicate that the hydrogen spillover process of Ni–La2O3 cermet hydrogen electrode can greatly promote the hydrogen oxidation reaction.

Hydrogen storage by spillover in porous carbon material (PCM) has achieved great success in experiments. During the past 20 years, a large number of theoretical works have been performed to explore the hydrogen spillover mechanism, look for high-performance hydrogen storage materials and high-efficiency catalysts. In this paper, we summarize and analyze the results of the past researches, and draw the following conclusions: (1) In PCM surface, the stability of chemisorbed H can be reached through phase nucleation process, which can be initiated in the vicinity of surface impurities or defects. (2) To achieve the 2020 U.S. Department of Energy (DOE) target, the PCM material used for hydrogen storage by spillover should have a sp2 carbon ratio greater than 0.43 and a surface area less than 3500 m2/g, which gives us an inspiration for exploring hydrogen spillover materials. (3) Due to a high barrier, the hydrogen spillover almost can not be initiated on pure PCM substrate at room temperature. By introducing the defects or impurities (e.g. holes, carbon bridges, oxygen functional groups, boron atoms and fluorine atoms), the spillover barriers can be reduced to a reasonable range. In addition, hydrogen atoms may also migrate in a gas phase. (4) According to our previous results of kinetic Monte Carlo simulations, there is a linear relationship between the reaction temperature and the migration barrier. The optimal barrier for the hydrogen spillover should be in the range of 0.60–0.88 eV. (5) Once the hydrogen atoms are chemically adsorbed on the carbon substrate, it is difficult to diffuse again due to the strong strength of C–H bond. Several theoretical diffusion mechanisms have been proposed. For example, the H atoms in physisorption state can diffuse freely on carbon surfaces with high mobility, using the shuttle gases (e.g. BH−4, H2O, HF and NH3) to make the migration thermodynamically possible and decrease the migration barrier, the H atoms diffuse inside the interlayer space of the bi- and tetralayer graphene, and introducing the impurities on the surface to facilitate the hydrogen diffusion. (6) The H desorption through the directly recombination or the reverse spillover is unlikely to occur at normal temperature. The Eley-Rideal reaction may be the only possible mechanism for desorption of the adsorbed H atoms in carbon substrate. Finally, we have made a prospect for further research works on hydrogen storage by spillover.

In this work, strontium tantalate (Sr2Ta2O7) nanowires were used for the first time as a support of ruthenium catalysts for ammonia synthesis. The highest ammonia synthesis activity of 1582 μmol g-1cat h-1 was observed with Ru/Sr2Ta2O7 catalysts prepared with molar ratio of Sr(OH)2/Ta2O5 at 4. After loading promoters, the ammonia synthesis activity was significantly improved to 4856, 5004 and 5038 μmol g-1cat h-1 for K-, Rb- and Cs- modified Ru/Sr2Ta2O7 catalysts. Characterization and kinetic experiments indicate that the improved ammonia synthesis rate of promoters-Ru/Sr2Ta2O7 catalysts was attributable to the combined effect of alleviated hydrogen poisoning through the promotion of hydrogen spillover from Ru species to support of Sr2Ta2O7 and enhanced activation of N2 due to increased electron density of Ru sites because of electron donation from introduced oxygen vacancies and promoters. The study not only clarifies the role of promoters in ammonia synthesis, but also provides an excellent Ru catalyst on Sr2Ta2O7 nanowires for ammonia synthesis.

In this work, the NiCu solid solutions with different Ni/Cu molar ratios were prepared and then doped into MgH2 through ball milling to modify its hydrogen sorption properties. The experimental results show that the Ni–25%Cu and Ni–50%Cu exhibit the superior catalytic effect over pure Ni, pure Cu and Ni–75%Cu on the dehydrogenation of MgH2. Among them, the 5h-milled MgH2/Ni–50%Cu system starts to desorb hydrogen at 205.8 °C, which is about 96.9 °C lower than that of as-milled pristine MgH2. Moreover, the MgH2/Ni-50% Cu system can release 5.14 wt% hydrogen at 300 °C within 15 min, while MgH2 can only release 2.92 wt% hydrogen under the same condition. More importantly, the dehydrogenated MgH2/Ni–50%Cu can reabsorb 4.37 wt% hydrogen even at 250 °C for 30 min. The enhanced hydrogen sorption kinetics of MgH2/Ni–50%Cu mainly attributes to the “hydrogen spillover” effect of in-situ formed Mg2Ni(Cu) phases. Further theoretical calculations reveal that the strong interactions between H and Ni/Cu result in the weakened stability of MgH2, decreased bond strength of Mg–H and enhanced dehydrogenation properties of MgH2. This research provides an important guidance for design multiple transition metals catalysts to improve efficiently hydrogen storage properties of magnesium-based and other metal-based hydrides.

Cerium zirconium-based (CZ) oxygen storage materials (OSMs) play a crucial role in three-way catalysts (TWCs), while CZ needs to be modified to satisfy more rigorous emission standard. In this study, transition metal (TMs = Mn, Cr, Fe, Cu) oxides modified CZ were prepared by incipient wetness impregnation method to improve the oxygen storage capacity of CZ-based materials. To clearly illustrate the influence of TM oxides, N2 adsorption-desorption, X-ray diffraction (XRD), oxygen storage capacity (OSC), temperature programmed reduction by H2 (H2-TPR) and X-ray photoelectron spectroscopy (XPS) were used to characterize the physical and chemical properties of samples. It is found that, all modified CZ have higher OSC, lower reduction temperatures than those of pristine CZ. Interaction between TMOs and CZ take precedence over specific surface to influence OSC. Notably, FeOx/CZ has the highest OSC, which is about 1.9 times that of CZ and it could be attributed to synergistic effect between FeOx and CZ; CuOx/CZ has the lowest reduction temperature which is 168°C lower than that of CZ, and it can be explained by hydrogen spillover effect.

Bimetallic Co-Cu catalysts are widely applied in higher alcohol synthesis (HAS), but the formation of the final active structure has not yet been fully clarified, especially for Co-rich catalysts. We investigated the structural evolution of a Co-Cu catalyst (Co:Cu = 2) from the hydrotalcite precursor containing additional Al3+ and Zn2+ to the final active state after 80 h under reaction conditions at 280 °C and 60 bar. The reconstruction of the bimetallic Co-Cu nanoparticles obtained by H2 reduction was induced by the feed gas consisting of an equimolar H2 and CO syngas mixture resulting in fast phase separation and sintering of metallic Cu0 and Co0 in the first 2 h time on stream (TOS) and a continuous carbidization of Co0 forming Co2C and its sintering until steady state was reached after 40 h TOS. An intergrowth of metallic Cu0 nanoparticles with Co2C nanoparticles was observed to occur under reaction conditions. The high selectivity to oxygenates amounting to 41% compared with 29% to hydrocarbons is ascribed to the multi-functional Co2C/Cu0 interface enabling dissociative CO adsorption, hydrogenation and CO insertion. The formation of hydrogenated carbon species (CxHy) originating from dissociative CO chemisorption is assumed to be favored by hydrogen spillover from Cu0 to Co2C. The adsorption sites for molecular CO provided by both Cu0 and Co2C facilitate its insertion into the CxHy intermediates thus leading to a higher selectivity to alcohols following the Anderson-Schulz-Flory distribution.

Mixed metal oxides as solid solutions are promising catalyst precursor species, due to their atomic dispersion of metals within an oxide matrix. Upon activation by pre-reduction highly dispersed metal nanoparticles grow on the surface of a functional mixed metal support. Herein, the impact of different amounts of structure distorting manganese that is integrated in CoMnxAl2-xO4 spinel phase on the reducibility as a measure for the ability for pre-activation was investigated. The reducibility of the spinel increases with increasing Mn content. By using the Sabatier reaction (CO2 methanation) as model reaction it was shown that the activity depends on the low temperature reducibility of the spinel. The highest catalytic productivity of 0.65 mol/(mol·min) at 400 °C was obtained with CoMn0.5Al1.5O4 as a precursor in line with a highly improved selectivity (S(CH4) = 97%) towards methane as compared to manganese free CoAl2O4. In addition, the activation energy drops from 107 kJ/mol to 69 kJ/mol upon Mn incorporation. Intense surface analysis via CO & H2 pulsed titration, BET, CO2-TPD, CO2 DRIFTS, as well as operando DRIFTS analysis revealed, that the integration of Mn into the spinel support decreases the overall surface basicity and enables, potentially due to its Mn3+/Mn2+ redox pairs, spillover of hydrogen from the metallic sites towards the surface of the support. This leads to an altered reaction mechanism via formate species without production of CO as reaction intermediates. This in combination with the ability to transfer the CO2 conversion from the metal sites only towards the surface of the support due to hydrogen spillover leads to the observed increase in catalytic performance. This work demonstrates the high potential of specific modification of typically highly stable mixed metal oxides as valuable catalyst precursor species.

The effect of the Al2O3 structure on the performance of Pt/Ga/Al2O3 catalysts is investigated for the direct dehydrogenation of propane. The study unveils that the structure of Al3+ determines the bulk structure of catalysts, particularly a high content of coordinatively unsaturated Al3+ sites (penta-coordinated Al3+, denoted as Al3+penta) could lead to a remarkably improved dehydrogenation activity of the catalyst. The bulk characterization reveals that the sufficient amount of Al3+penta in Al2O3 benefit the dispersion of Pt and Ga2O3 on the Al2O3 support. At the same time, TPR results reveal that the presence of Pt facilitates the reduction of Ga2O3, likely due to the hydrogen spillover between the well dispersed Pt and Ga2O3, which consequently enhances the synergistic function between Pt and Ga2O3 in the dehydrogenation of propane. Recyclability tests demonstrate that the dehydrogenation activity stabilizes after three cycles over the Pt/Ga/Al2O3 catalyst.

Catalytic chemical reduction of nitrate without generating harmful nitrite and ammonium is still a challenge limiting the application of this technology to the production of drinking water. In this work a new approach was proposed based on shielding of Pd active sites in PdCu catalysts by sodium bis-2-ethylhexyl sulphosuccinate (AOT). To study this concept and the interactions between PdCu and AOT, carbon-supported PdCu catalysts were prepared by microemulsion using AOT as surfactant, and by incipient wetness impregnation followed by exposure to AOT. All the catalysts based on AOT showed lower activity in nitrate reduction than those prepared by ordinary incipient wetness impregnation, however ammonium generation was prevented thanks to shielding of Pd active sites by AOT. Bimetallic catalysts prepared by physically mixing Pd and Cu monometallic catalysts and exposure to AOT revealed a lower activity in nitrate reduction, which was ascribed to the interference of AOT in the Pd–Cu redox mechanism and lower hydrogen spillover. However, the catalysts maintained the ability to reduce nitrite with negligible production of ammonium, showing that shielding of Pd active sites can be an interesting approach to avoid nitrite and ammonium formation in nitrate reduction, but a compromise between activity and selectivity must be achieved.

The effect of nickel additive on Pd/TiO2 catalyst for selective catalytic reduction of NO with H2 in presence of O2 was investigated. Synergistic effects between palladium and nickel were found on the catalytic activity and N2 selectivity for the H2-SCR reaction. Hydrogen adsorption isotherm and transient reaction experiment results showed that the nickel additive enhanced the distance and rate of hydrogen spillover. Operando diffuse reflectance infrared spectroscopy (DRIFTS) with transient experiments indicated that addition of nickel to Pd/TiO2 led to the formation of extra active monodentate nitrates, and enhanced the activities of the bidentate nitrates. These positive effects on the formation of spiltover hydrogen and active adsorbed NOx species led to the promotional effect on the extra reaction intermediate NHx species, which was crucial for the enhancement of H2-SCR activity. All these results, from a view of reaction mechanism, provided a promising way for rational preparation of high-performance H2-SCR catalysts.

A new process for the low-cost synthesis of 2,6-DMN, the high-efficiency transalkylation of C10 aromatics (C10A) with 2-MN in H2 atmosphere was developed depending on a multifunctional SiO2(Ⅱ)-3.0%Mo-HBeta catalyst with three kinds of active sites located only inside its 12-ring channels. Firstly, the high-efficient synergistic catalysis from metal-Mo monomer and Lewis & Bronsted acid-sites significantly improved transalkylation, attributed to a surface behavior (involving hydrogen spillover) may producing the active hydrogen-species which markedly enhance the proton-transfer efficiency in this proton-acid catalytic reaction. Secondly, the hydrogenation & subsequent ring-opening etc. side-reactions of naphthalene series and the formation of multi-alkylnaphthalene byproducts were almost completely suppressed due to both the passivation of the external surface of catalyst and the transition-state shape-selectivity & the diffusion-constraint effect inside pores. Besides, both the reasonable catalytic-hydrogenation (from metal-Mo monomer) immediately converting light olefins (from dealkylation) into alkanes and the transition-state shape-selectivity suppressing the formation of larger-molecular multi-alkylnaphthalenes in channels, effectively prevented from the coking-deactivation of catalyst. As a result, the 2-MN conversion of above 75.3% and the 2,6-DMN yield of above 9.7% were obtained during the 50 h on-stream reaction. Our work may provide a promising model for rationally designing the elegant catalyst for a complicated conversion reaction.

The ruthenium-nickel bimetallic nanoparticles supported on carbon black (Ru-Ni/C) with various Ru and Ni loadings, while keeping a constant Ru/Ni atomic ratio (51/49), were synthesized at ambient temperature by liquid reduction with hydrazine hydrate as reducing agent and galvanic replacement reaction approaches. Different Ru-Ni interfaces (Ru-Ni-NiO with 1.250 wt% or 0.630 wt% Ru, and RuO2-NiO with 0.160 wt% Ru) were formed after being annealed in N2 at 380 °C for 3 h. Several techniques, including powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution TEM (HRTEM) and synchrotron radiation X-ray absorption spectroscopy (XAS) and in-situ XAS (in hydrogen) have been employed for structural characterization. It was found that most Ru atoms and a small amount of Ni atoms at the Ru-Ni-NiO interface were reduced, leading to the occurrence of hydrogen spillover and hence synergy effect of Ru, Ni and NiO active sites. However, such a synergy was not observed at the RuO2-NiO interface. The catalytic properties of the Ru-Ni/C nanocatalysts in the hydrogenation of benzene reaction were significantly improved due to the presence of particular Ru-Ni-NiO interface.

Hydrogen adsorption and desorption over Ru/SiO2 and Ru/Vulcan are investigated in terms of hydrogen storage and release characteristics by both dynamic and static experiments. Ru particle dispersions as a function of metal loading were determined by HR-TEM and volumetric chemisorption experiments. Vulcan was more accommodating for spillover hydrogen than SiO2. High Ru dispersions, i.e., small particle sizes, favored the amount of hydrogen spillover to Vulcan, as revealed by temperature programmed desorption (TPD) of hydrogen. TPD of hydrogen under He flow experiments over Ru/SiO2 and Ru/Vulcan materials revealed a low temperature process (up to 200 °C) attributed to desorption of weakly bound hydrogen from Ru metal surface. A high temperature process (above 450 °C) was attributed to diffusion of hydrogen from the support to the Ru particle and desorption at the Ru sites. Hydrogen adsorbs strongly on Ru metal, as indicated by the initial heats of H2 adsorption measured as 100 kJ/mol over 1 wt% Ru/Vulcan by adsorption calorimetry. At higher coverages, heat of adsorption of hydrogen was measured as 10 kJ/mol. Low heat of adsorption of hydrogen at high coverages indicate multilayer weak adsorption of hydrogen over the storage material, which can desorb at lower temperatures.

Site-selective deoxygenation of hydroxyl groups represents essential processes to access valuable functionalized bio-based compounds with industrial potential. One of the challenging tasks in this context is to convert biodiesel-derived glycerol in the presence of abundant water directly to 1,3-propanediol (1,3-PDO), a key component of the emerging polymer industry. Herein, a monometallic iridium supported on H-ZSM-5 in the absence of Re oxophilic metal oxides was prepared via grinding-assisted impregnation procedures and attempted as an effective and recyclable catalyst for the aqueous-phase selective hydrogenolysis of glycerol toward 1,3-PDO in the absence of acid additives. The results revealed the necessity to control the Ir domain dispersions, Ir0/Ir3+ ratio and the amounts of overall acid/Bronsted acid sites. Activity depended linearly on the amount of overall and Bronsted acid sites, and 1,3-PDO selectivity increased in the presence of Ir-induced Bronsted acid sites, denoted as Ir-O(H)-H-ZSM-5. We speculate that Ir-O(H)-H-ZSM-5 are generated by the interfacial synergistic interaction between IrOx and H-ZSM-5 through hydrogen spillover and reverse hydrogen spillover according to the reported literatures. The reaction mechanism to elucidate the role of Ir-O(H)-H-ZSM-5 sites in glycerol hydrogenolysis was also postulated based on extensive characterization and catalytic reaction results.

In this work, multiwalled carbon nanotubes (MWCNTs) promoted Co–B catalysts for NaBH4 hydrolysis have been designed and synthesized. The structural features of as-prepared catalysts have been investigated and discussed as a function of MWCNTs contents by X-ray diffraction, X-ray photoelectron spectra, N2 adsorption/desorption isotherms, scanning electron microscope. The results show that the catalysts still maintain an amorphous structure with the addition of carbon nanotubes promoter. However, the appropriate amount of MWCNTs promoter in Co–B catalysts leads to large specific surface area, fine dispersion of active components, increased active sites and high electron density at active sites. Moreover, hydrogen spillover on the catalyst is promoted, which contributes to regeneration of active sites and accelerating catalytic cycle. Among all the experimental samples, it is found that the Co–B catalyst promoted by 10 wt% carbon nanotubes exhibits optimal catalytic activity with remarkably high hydrogen generation rate of 12.00 L min−1·gcatalyst−1 and relatively good stability.

A zirconia supported nickel catalyst for CO2 methanation has been prepared via a rapid and effective plasma decomposition of nickel precursor at atmospheric pressure and temperature around 150 °C, followed by hydrogen reduction at 500 °C. The obtained Ni/ZrO2 catalyst shows high Ni dispersion with principally exposed Ni(111) lattice plane. An enhanced cooperation between Ni and interfacial active sites is achieved as well, which leads to rapid dissociative adsorption of H2 and hydrogen spillover. Sufficient H atoms are thereby generated for CO2 hydrogenation and helpful to create oxygen vacancies on the ZrO2 surface. Higher basicity correlated to the oxygen vacancies further enhances CO2 adsorption and activation. Hence, a superior low temperature activity for CO2 methanation was achieved. For example, a CO2 conversion of 71.9% with a CH4 yield of 69.5% was achieved over the plasma decomposed catalyst at 300 °C with a feeding gas consisting of H2 (32 ml min−1), CO2 (8 ml min−1) and N2 (10 ml min−1) at a GHSV of 60,000 h-1. The corresponding TOF value towards CO2 conversion is 0.61 s-1. However, the CO2 conversion, CH4 yield and TOF value are only 32.9%, 30.3% and 0.39 s-1 at the same reaction conditions over the thermally prepared catalyst. The operando DRIFT analyses demonstrate that CO2 methanation over the plasma decomposed catalyst follows the CO-hydrogenation route. The exposed high-coordinate Ni(111) facets of the plasma decomposed catalyst facilitate the decomposition of CO2 and formates into adsorbed CO. The subsequent hydrogenation of adsorbed CO leads to the production of methane. However, the thermally decomposed catalyst with complex Ni crystal structure and more defects mainly takes the pathway of direct formate hydrogenation. The present study confirms the structure of Ni/ZrO2 has significant effect on the catalytic activity for CO2 methanation.

The objective of this study was to investigate the effect of Cu addition to carbon supported Ru catalysts on the hydrogenation of macroalgae-derived alginic acid into sugar alcohols, mainly sorbitol and mannitol. Both geometric and electronic effects were determined based on results of H2-TPR, H2- or CO-chemisorption, and XPS analyses after Cu was added to Ru. The addition of Cu to Ru caused blocking of active Ru surface and electron transfer between Ru and Cu. The intimate interaction between Ru and Cu formed RuCu bimetallic clusters which expedited hydrogen spillover from Ru to Cu. The highest yield of target sugar alcohols of 47.4% was obtained when 5 wt% of Ru and 1 wt% of Cu supported on nitric acid-treated activated carbon reacted at 180 °C for 2 h. The RuCu bimetallic catalyst exhibited deactivation upon repeated reactions due to the carbon deposition on the catalyst.

Ammonia (NH3) is a carbon-free Hydrogen carrier with the advantages of high volumetric energy density, developed infrastructure, as well as easy and safe storage. The coupling of NH3 catalytic decomposition with electrochemical oxidation in an anode of solid oxide fuel cells leads to the field of direct Ammonia-fueled solid oxide fuel cell. However, the related coupling mechanism needs clarification. In the present study, by developing a mechanistic model and a library of elementary reaction kinetics, we attempt to have an overview on the synergism of heterogeneous reactions, charge-transfer reactions, bulk diffusion, and charge-transfer processes of direct Ammonia-fueled solid oxide fuel cell. We describe charge-transfer reactions based on hydrogen spillover mechanism as well as oxygen spillover mechanism, and find that only the hydrogen spillover mechanism fits with experimental data. With this validated model, we identify the rate-determining steps as well as the main surface species in H2-fueled and NH3-fueled solid oxide fuel cells. We define the region of NH3 catalytic decomposition and that of electrochemical oxidation to quantify the coupling within the anode. Based on the quantification results, we study the effects of temperature and content of inlet NH3 on cell performance.

We studied on the function of Pd species located in mesopores and inside zeolite channels (micropores) of the montmorillonite-modified zeolite catalyst for the hydrodesulfurization of diesel fraction with 350 ppm of sulfur as DBT, 4-MDBT, and 4,6-DMDBT. It was shown that the ex-dihydrogentetrachloropalladate impregnated catalyst as well as the ex-tetraamminepalladium(II) chloride ion-exchanged catalyst have high efficiency of sulfur removal from the diesel fuel in temperature range 280–300 оC. The sulfur tolerance of catalyst depended on the method of Pd adding. The catalyst prepared by ion-exchange with tetraamminepalladium chloride solution exhibited the highest sulfur tolerance. According to FTIR of adsorbed CO, this catalyst contains a small Pd metal atoms or cluster in electron-deficient state inside zeolite channels. They probably ensure sulfur tolerance due to hydrogen spillover. The montmorillonite addivite significantly modifies performance of the Pd-Zeolite catalyst in hydrotreating of diesel fraction. It leads to a decrease of cracking function, while those of hydrogenolysis of sulfurorganic molecules and hydrogenation of aromatic molecules are strengthened in comparison with the unmodified catalyst. This effect is explained by the change of acidic properties of the catalyst, limitations of diffusion of various molecules into the zeolite channels, and diffusion of Pd from the zeolite channels.

An efficient and low-cost supported Pt catalyst for hydrogenation of niroarenes was prepared with colloid Pt precursors and α-Fe2O3 as a support. The catalyst with Pt content as low as 0.2 wt% exhibits high activities, chemoselectivities and stability in the hydrogenation of nitrobenzene and a variety of niroarenes. The conversion of nitrobenzene can reach 3170 molconv h−1 molPt−1 under mild conditions (30 °C, 5 bar), which is much higher than that of commercial Pt/C catalyst and many reported catalysts under similar reaction conditions. The spatial separation of the active sites for H2 dissociation and hydrogenation should be responsible for the high chemoselectivity, which decreases the contact possibility between the reducible groups of nitroarenes and Pt nanoparticles. The unique surface properties of α-Fe2O3 play an important role in the reaction process. It provides active sites for hydrogen spillover and reactant adsorption, and ultimately completes the hydrogenation of the nitro group on the catalyst surface.

In this work, a Pd/MgAl-LDH catalyst was synthesized by the ion-exchange and liquid-reduction process (IE), with impregnation method (IM) as contrast, to study the difference in the interfacial structure induced by the preparation methods and the catalytic behavior for selective hydrogenation of 2-ethylanthraquinone. STEM-EDS measurement reveals that the IE-Pd/MgAl-LDH catalyst possesses an obvious sandwich structure of which Pd nanoparticles uniformly located in the LDH interlayer space, and therefore exhibits more Pd-LDH interface sites due to the high intimacy. More importantly, it was confirmed that the Pd-LDH interface structure was characterized by rich oxygen vacancies (Vo) due to the loss of surface hydroxyl groups on the LDH layer during the ion-exchange process. As expected, the IE-Pd/MgAl-LDH catalyst exhibited a 127% higher H2O2 yield than that of IM-Pd/MgAl-LDH catalyst. High activity was attributed to the facilitated hydrogen activation resulting from significantly enhanced hydrogen spillover over the Pd-LDH interface structure. Preferred selectivity was owing to the special adsorption mode of C O bond interacted with the Pd-Vo interfacial sites, which leads to the selective activation of C O bond. This work develops a feasible approach to fabricate the metal-hydroxide interface structure and provides a fundamental understanding on interfacial effect toward selective hydrogenation of C O bonds.

Selective hydrocleavage of aromatic C O bond while preserving the aromatic ring is a desired catalytic process in hydrodeoxygenation (HDO) of biomass derived aromatic oxygenates to high value biochemicals. Guaiacol with typical methoxy and phenolic hydroxyl groups is a representative aromatic di-oxygenates of lignin fragments. Sub-nanometer sized silver, a poor hydrogenation metal catalyst, was found to initiate H2 dissociation and H spillover onto anatase TiO2 (TiO2-A) surface. The spillover hydrogen enhanced the partial reduction of TiO2-A surface at a substantially lowered temperature as compared to the reduction of TiO2-A by molecular H2. The reduction of TiO2-A surface by spillover hydrogen was enhanced at Ag loading as low as 0.01 wt% on TiO2-A. The ratio of spillover H to Ag was as high as 675 at Ag loading of 0.01 wt% and the ratio decreased with increasing Ag loading. We found that the yield of phenolic products was linearly correlated with the amount of spillover hydrogen that created oxygen vacancy (Ov) through partial reduction of TiO2-A surface. Methanol was formed as the main side-product, indicating that the direct hydrocleavage of aromatic C-OCH3 in guaiacol is favored over that of aromatic C-OH on the created site.

In this work, CuO-TiO2 nanoparticles with different CuO mass contents of 2%, 8%, 12%, and 20% are synthesized by flame spray pyrolysis (FSP) method and applied to catalytic combustion of lean CO. The nano-catalyst is characterized by N2-physisorption isotherms, X-ray diffraction (XRD), transmission electron microscopy (TEM), H2-TPR (temperature-programmed reduction) and X-ray photoelectron spectroscopy (XPS). All the catalysts possess a high specific surface area, of which the CuO-TiO2 nanoparticles with 2 wt.% Cu (2CT) is as high as 98 m2/g, and exhibits a spherical structure with a diameter of 15–20 nm. Compared with other methods, the FSP method can significantly improve the loading of CuO without producing large crystalline CuO particles on the catalyst surface. Interestingly, the addition of CuO will essentially change the lattice structure of TiO2 for all catalysts, including its crystal spacing and XRD diffraction angle. Copper cations are embedded in TiO2 lattice to promote the transformation from anatase to rutile by producing oxygen defect at high flame temperature. The interaction between CuO and TiO2 has significant influence on its physicochemical properties. A lower onset reduction temperature on the sample with higher CuO loading is obtained due to the hydrogen spillover effect in H2-TPR test. Moreover, the loaded CuO increases the content of more stable rutile phase in the materials, so that it reduces the strong metal-support interaction (SMSI) effect of CuO and anatase phase to improve the properties of CO catalytic combustion. The synthesized CuO-TiO2 nanoparticles can achieve complete combustion conversion of lean CO at lower temperature of 120°C.

Hydrogen uptake of pristine multi-walled carbon nanotubes is increased more than three-fold at 298 K and hydrogen pressure of 4.0 MPa, upon addition of hydrogen spillover catalyst manganese oxide, from 0.26 to 0.94 wt%. Simple and convenient in situ reduction method is used to prepare Mn-oxide/MWCNTs composite. XRD, FESEM, and TEM demonstrates nanostructural characterization of pristine MWCNTs and composite. TGA analysis of Mn-oxide/MWCNTs composites showed a single monotonous fall related to MWCNTs gasification. Enhancement of hydrogen storage capacity of composite is attributed to spillover mechanism owing to decoration of Mn-oxide nanoparticles on outer surface of MWCNTs. Hydrogen uptake follows monotonous dependence on hydrogen pressure. Oxide-MWCNTs composite not only shows high hydrogen storage capacity as compared to pristine, but also exhibit significant cyclic stability upon successive adsorption–desorption cycles.

Pd promoted Ni supported on C60 derivative was prepared and employed to catalyze the hydrogenation of nitrobenzene (NB). The effects of the function groups of C60 derivatives and Pd on the catalytic performance of Ni-based catalyst were investigated. The characterizations illustrated that the function groups of C60 derivatives significantly affected the chemical state of Ni and Pd, which resulted in different catalytic performance. In addition, Pd as a promoter promoted the in-situ reduction of Ni under mild conditions via hydrogen spillover. Pd-Ni-N-C60, derived from C60-ethanediamine derivative with the molar ratio of Ni to Pd of 6:1, exhibited excellent catalytic performance. The high surface contents of Pd0, electron-rich Ni species and the synergistic effect between Pd, Ni and C60-ethanediamine were responsible for the outstanding catalytic performance. Under 70 °C and 1.0 MPa of H2, the nitrobenzene conversation of 98.0% and the aniline selectivity of 98.2% were obtained over Pd-6Ni-N-C60 with the reaction rate of 36.7 mol NB/(mol metal·min). The H2 pressure in the range of 0.1 MPa and 0.8 MPa obviously affected the aniline selectivity at 90 °C.

Reductive catalytic conversion of DDT (p,p′-dichlorodiphenyltrichloroethane) was studied under ambient conditions in a hydrogen atmosphere using platinum and palladium deposited on several supports, in particular on porous alumina and silica. Almost complete hydrodechlorination and hydrogenation of DDT and its dehydrochlorination byproduct DDE (p,p′-dichlorodiphenyldichloroethene), leading to the formation of diphenylethane (with Pd) and dicyclohexylethane (with Pt), were observed at ambient temperature within minutes or hours. Rapid hydrodechlorination also takes place after depositing DDT and the metal component on separate particles and mixing them mechanically. This long-range reactivity can be explained either by a fast surface diffusion of DDT or DDE, or by hydrogen spillover. Irrespective of the mechanism, the reactivity thus bridges the barrier across solid particle interfaces. Most findings indicate the fast diffusion of target compounds as dominant mechanism for the observed long-range reactivity.

A remote control model material was developed, which consists of a sulfur-tolerant Pt/Al2O3@sodalite catalyst and a CoMo/Al2O3 catalyst and which combines the concepts of size-selectivity and hydrogen spillover. The Pt/Al2O3@sodalite with core shell structure was prepared by coating a Pt/Al2O3 core with a nanosized sodalite (SOD) shell. The cages of the SOD are sufficiently small (0.3 nm) to exclude the smallest sulfur-containing molecules (hydrogen sulfide, 0.36 nm), while allowing hydrogen molecules (0.289 nm) and atomic hydrogen to diffuse in and out of the cages to allow hydrogen spillover. The Pt/Al2O3@sodalite core–shell material combined with traditional sulfided cobalt molybdenum showed high activity, stability, and high sulfur resistance in the hydrodesulfurization of dibenzothiophene. The Pt/Al2O3@sodalite core–shell material (where hydrogen spillover starts) is used as active hydrogen emission sources, producing active hydrogen and transporting it to the traditional sulfided cobalt molybdenum catalyst (where the spilled over hydrogen is used).

Platinum (Pt) is one of a robust hydrogen dissociative catalyst. However, the migration of dissociated hydrogens from Pt nanoparticles to carbon supports such as graphene and carbon nanotube are energetically unfavorable reactions. To enhance the hydrogen storage via migration mechanism, carbon nanohorn is applied as a support for Pt nanoparticles (Pt and Pt4). The H2 storage performance of Pt and Pt4 supported on the mono-vacancy carbon nanohorn (vNH) has been investigated by using density functional theory calculations. The Pt and Pt4 firmly deposit at the vacancy site through the three strong Pt–C bonds with binding energies about −7.0 eV, which can prevent the metal desorption and migration. The mechanism of H2 storage starts with H2 adsorption followed by H2 spillover reaction. The calculation results reveal that the supported Pt nanoparticles are the active sites for H2 dissociative adsorption while the high curvature surface of carbon nanohorn is the active area for accommodating the migrated H atoms from the spillover reaction. Remarkably, the hydrogen spillover reactions over Pt– and Pt4-supported on vNHs in this study are spontaneous at room temperature with highly exothermic reaction energy. The fundamental understanding obtained from this study is beneficial for further design and synthesis of high-performance materials for H2 storage applications.

Currently, renewable biomass-derived energy sources and related transformation technologies are attracting numerous attentions due to the rapid consumption of fossil fuels and resulting increasing environmental pollution. Herein, a new dandelion-like cobalt oxide (CoOx) microsphere-supported bimetallic RuCo catalyst was fabricated by a simple one-pot embedding method and employed for the 5-hydroxymethylfurfural (HMF) hydrogenolysis to produce liquid 2,5-dimethylfuran (DMF) biofuel. It was found that bimetallic RuCo nanoparticles (NPs) with the average size of about 2.5 nm could homogeneously disperse on flower-like CoOx microspheres possessing abundant surface defects (i.e. oxygen vacancies and Co2+ species) simultaneously constructed. As-fabricated RuCo/CoOx catalyst exhibited excellent catalytic performance in above reaction, along with a quite high DMF yield of 96.5% at a high HMF/Ru molar ratio of 252.7, which was corelated with the unique synergy between bimetallic RuCo NPs and abundant surface defects at the metal-support interface, as well as the enhanced hydrogen spillover effect and the dandelion-like superstructure of the catalyst. Additionally, the strong interactions between RuCo species and the CoOx matrix in the RuCo/CoOx significantly prevented RuCo NPs from migration, aggregation, and leaching during the reaction. The present findings offer a new approach for designing other highly efficient and stable bimetallic catalysts applied in a variety of heterogeneous catalytic systems.

Developing effective nickel-based catalysts in hydrogenation of pyrolysis gasoline (PyGas) is of great importance in chemical industry. Herein, we report a facile fabrication of Al2O3-supported NiRu bimetallic catalysts, with Ru content ranging from 0.01 wt% to 0.1 wt%, by reducing of precursors of Ni2+Ru3+Al3+-containing layered double hydroxides (NiRuAl-LDHs) in flowing hydrogen. Their catalytic performance was evaluated by styrene hydrogenation, a model reaction in industrial hydrogenation of PyGas (abbreviated as PyGasMF). The LDH precursors initially in situ grow on the surface of microspherical γ-Al2O3 supports. Doping Ru3+ in LDH main layers promotes reduction of Ni2+ by hydrogen spillover and decreases significantly the size of Ni metal particles, and NiRu alloy particles are formed during the reduction. Substitution of an appropriate amount of Ni for Ru enhances the catalytic activity and stability in styrene hydrogenation, demonstrating a synergistic effect of Ni and Ru on hydrogenation reactivity.

Ag/CeO2 nanosphere catalysts were successfully tuned by sodium doping to promote low-temperature catalytic oxidation of formaldehyde (HCHO). It was observed that sodium-promoted Ag/CeO2 nanosphere catalysts exhibited relatively high intrinsic catalytic activity. Different characterization techniques were performed on the catalysts to elucidate the physicochemical properties that contributed to the improvement of the catalytic performance. Due to electron charge transfer from Ag to CeO2 nanospheres, Ag species should comprise of Ag2O as main components along with parts of metallic Ag over CeO2 nanospheres, while remaining as metallic Ag over conventional CeO2 bulk particles. The well-dispersed Ag species on CeO2 nanospheres could activate surface oxygen from CeO2, and facilitate the surface reduction of CeO2 nanospheres. The doped sodium might exist in the forms of NaHCO3 and Na2CO3 compounds, which could cause that surface hydroxyl (OH−) concentrations significantly increased on the surface of CeO2 nanospheres. The presence of sodium compounds could prevent hydrogen spillover from Ag to CeO2 supports, attesting to the inhibiting role of sodium species in the reduction process. However, with the introduction of sodium into Ag/CeO2 nanospheres, surface hydroxyl groups would become important reaction species and directly react with adsorbed surface formate species (HCOO−) to form H2O and CO2. This reaction route was inconsistent with that over Ag/CeO2 nanospheres, on which bidentate HCOO− were the key intermediates during catalytic oxidation of HCHO, and the further oxidation of HCOO− by activated surface lattice oxygen was the rate-determining step. These results provide guidance for designing highly efficient and economic silver-based catalysts for HCHO catalytic oxidation.

The catalytic property of the bimetallic Ni/Pd, Ni/Pt and Pt/Pd particles for hydrogen spillover on penta-graphene (PG) are studied by using the first-principles and kinetic Monte Carlo (KMC) calculations. The bimetallic Ni/Pd, Ni/Pt and Pt/Pd particles can be stably decorated on PG surface with binding energies in the range of 4.15–5.52 eV. The adsorption enthalpies of H2 molecules on bimetallic particles are in the range of −11.56–−15.35 kcal/mol. The H atom can migrate from the bimetallic particles to PG with the migration barriers range from 0.67 to 0.95 eV. The KMC simulations show that the hydrogen spillover reactions can occur at a suitable temperature (260–361 K), which meet DOE target for onboard hydrogen storage systems applied to light-duty vehicles. In the study, the highest occupied molecular orbital and electric field analysis shows that the bimetal mixing can reduce the hydrogen adsorption enthalpy, and thereby reduce the H migration barrier, which displays a synergistic effect for hydrogen spillover.