Catalytic action of platinum on coke burning

Syngas production over La0.9NiyAl11.95-yO19-δ catalysts during C14-alkane partial oxidation: Effects of sulfur and polycyclic aromatic hydrocarbons

Ni-BTC metal-organic framework loaded on MCM-41 to promote hydrodeoxygenation and hydrocracking in jet biofuel production

Incorporating oxophilic metals into noble metal-based catalysts represents an emerging strategy to improve the catalytic performance of electrocatalysts in fuel cells. However, effects of the distance between the noble metal and oxophilic metal active sites on the catalytic performance have rarely been investigated. Herein, we report on ultrasmall (∼5 nm) Pd–Ni–P ternary nanoparticles for ethanol electrooxidation. The activity is improved up to 4.95 A per mgPd, which is 6.88 times higher than commercial Pd/C (0.72 A per mgPd), by shortening the distance between Pd and Ni active sites, achieved through shape transformation from Pd/Ni–P heterodimers into Pd–Ni–P nanoparticles and tuning the Ni/Pd atomic ratio to 1:1. Density functional theory calculations reveal that the improved activity and stability stems from the promoted production of free OH radicals (on Ni active sites) which facilitate the oxidative removal of carbonaceous poison and combination with CH3CO radicals on adjacent Pd active sites.

The selective hydrogenation of alkynes to their corresponding alkenes is an important type of organic transformation, which is currently accomplished by modified palladium catalysts. Herein, we rep...

Ultrafine PdRu Nanoparticles Immobilized in Metal–Organic Frameworks for Efficient Fluorophenol Hydrodefluorination under Mild Aqueous Conditions

New insights into the catalytic mechanism of VOCs abatement over Pt/Beta with active sites regulated by zeolite acidity

Lanthanum hexaaluminate — novel thermal barrier coatings for gas turbine applications — materials and process development

Surface Coordination Decouples Hydrogenation Catalysis on Supported Metal Catalysts

Recommendations for improving rigor and reproducibility in site specific characterization

The modification of Ni/Al2O3 catalyst by alkaline earth metal oxides including MgO, CaO, SrO and BaO was investigated for hydrogen production from the partial oxidation and reforming of dimethyl ether. MgO modification of the Ni/Al2O3 catalyst enhanced the formation of NiAl2O4. There was only one reduction peak from 700 to 950 °C, which is usually ascribed to the reduction of NiAl2O4. The Ni-containing species which are easily reduced at low temperature were removed. When the MgO modified Ni/Al2O3 was reduced at 750 °C in the performance evaluation, a small amount of Ni was produced from NiAl2O4 to give small and active Ni sites, resulting in better catalytic reforming performance than for the unmodified Ni/Al2O3. The H2 yield of 88% and CO selectivity of 86% was obtained at 800 °C when MgO modified Ni/Al2O3 was adopted as a reforming catalyst, which was combined with 0.5 wt% Pt/Al2O3 to form a dual bed catalysts. The other metal (Ca, Sr, Ba) oxide modification of Ni/Al2O3 catalyst, however, did not enhance the formation of NiAl2O4 as well as MgO, and there were still certain amounts of low temperature reducible NiO species, resulting in a worse catalytic performance than the unmodified Ni/Al2O3. The variation of the amount of MgO modification had no obvious effect on the formation of NiAl2O4. However, the peak reduction temperature of 7.5 wt% MgO modified Ni/Al2O3 in H2-TPR patterns was a little lower than that of 5.0 or 10.0 wt% MgO modified Ni/Al2O3, resulting in a little better catalytic performance by giving more active Ni sites reduced from NiAl2O4 at 750 °C.

Controlled Assembly of Hierarchical Metal Catalysts with Enhanced Performances

As non-precious catalysts, Ni-based catalysts play a significant role in methanol oxidation for energy conversion technologies. At the same time, the effect of the complicated chemical environment on catalytic efficiency remains unclear. Here, the coordination environment of Ni active sites in spinel nickel-manganese (NiMn2O4 and MnNi2O4) is investigated as a platform to elucidate the correlation with catalytic performance in methanol electro-oxidation. The occupation of Ni2+ ions in these structures modulates the intrinsic activity of Ni active sites in NiMn spinels, resulting in different catalytic mechanisms and intrinsic active site efficiency, although they have similar morphology and structure. The high-symmetry NiO6 octahedral structure in inverse spinel MnNi2O4 exhibits superior catalytic performance and stability compared to the NiO4 tetrahedral structure in normal NiMn2O4 spinel. Specifically, at 1.50 V vs. RHE, the MnNi2O4 inverse spinel delivers mass activity and specific activity for methanol oxidation that are 1.9 and 3.5 times those of the normal NiMn2O4 spinel, respectively. Furthermore, it also maintains a stable current density of 33.5 mA cm-2 at 1.56 V vs. RHE for 25 hours. Theoretical calculations reveal that Ni sites in MnNi2O4 exhibit a significantly lower activation energy barrier and enhanced CO anti-poisoning capability compared to those in NiMn2O4. The Ni site-dependent coordination environment in spinel structures provides useful insights into catalyst development and the methanol oxidation mechanism.

Constructing highly dispersed Ni based catalysts supported on fibrous silica nanosphere for low-temperature CO2 methanation

Propane Dehydrogenation on Single-Site [PtZn4] Intermetallic Catalysts

Photocatalytic water splitting for clean hydrogen production has been a very attractive research field for decades. However, the insightful understanding of the actual active sites and their impact on catalytic performance is still ambiguous. Herein, a Pr-doped TiO2-supported Cu single atom (SA) photocatalyst is successfully synthesized (noted as Cu/Pr-TiO2). It is found that Pr dopants passivate the formation of oxygen vacancies, promoting the density of photogenerated electrons on the CuSAs, and optimizing the electronic structure and H* adsorption behavior on the CuSA active sites. The photocatalytic hydrogen evolution rate of the obtained Cu/Pr-TiO2 catalyst reaches 32.88mmolg-1h-1, 2.3 times higher than the Cu/TiO2. Innovatively, the excellent catalytic activity and performance is attributed to the active sites change from O atoms to CuSAs after Pr doping is found. This work provides new insight for understanding the accurate roles of single atoms in photocatalytic water splitting.