Enhancement Of Catalytic Performance Research Articles

Non-noble trimetallic Cu-Ni-Co nanoparticles supported on metal-organic frameworks as highly efficient catalysts for hydrolysis of ammonia borane

Highly dispersed non-noble trimetallic Cu-Ni-Co nanoparticles can be successfully immobilized onto the pores of the metal-organic framework, MIL-101, by a simple solvent evaporation method. The Cu-Ni-Co@MIL-101 nanoparticles exhibit excellent catalytic effect on the hydrolysis of ammonia borane at 25 °C. Compared to their bimetallic and monometallic counterparts, Cu-Ni-Co trimetallic catalysts display superior catalytic activity. Careful investigation reveals that Cu0.8Ni0.1Co0.1@MIL-101 (Cu:Ni:Co atomic ratio = 8:1:1) displays a total turnover frequency (TOF) value of 72.1 molH2 molcat−1 min−1. This is the highest TOF value reported for non-noble metal catalysts to date and is even superior to values afforded by some noble metal catalysts (Au, Pt and Pd). The apparent activation energy of Cu0.8Ni0.1Co0.1@MIL-101 can be as low as 29.1 kJ mol−1. This remarkable enhancement in catalytic performance is attributed to the large catalyst surface as well as the synergetic effect between Cu, Ni, and Co supported on MIL-101. This study provides a new strategy for the preparation of high performance non-noble metal catalysts for the practical hydrolysis of hydrogen storage systems, thereby fast-tracking the application of ammonia borane in fuel cells.

Enhanced catalytic performance of Ni/SBA-15 towards CO2 methanation via P123-assisted method

This study focused on the enhancement of catalytic performance of Ni/SBA-15 towards CO2 methanation via P123(PEG-PPG-PEG triblock copolymer)-assisted impregnation method. The physical and chemical properties of the catalysts were characterized using XRD, BET, TEM, and FTIR, meanwhile the catalytic performance of catalysts towards CO2 methanation were evaluated using stainless steel fixed bed reactor. The presence of coke on the surface of catalysts was characterized using TGA analysis. XRD, BET and TEM results revealed that the dispersion of Ni particles on the surface of SBA-15 were improved with P123 (Ni/SBA-15(P123)) as compared to without P123 (Ni/SBA-15). FTIR analysis revealed that P123 enhanced the formation of metal-support interaction (Si-O-Ni) through the substitution of O-H with O-Ni. Ni/SBA-15(P123) exhibited higher catalytic activity with 90.3% CO2 conversion and 97.5% CH4 selectivity, meanwhile Ni/SBA-15 showed lower catalytic activity with 81.6% CO2 conversion and 97.1% CH4 selectivity at temperature of 623 K. Apart from higher catalytic activity, Ni/SBA-15(P123) also showed better stability than that of Ni/SBA-15 whereby no carbon formation detected in TGA analysis for 48 h time on stream. The promising performance of Ni/SBA-15(P123) associated to its smaller metal particles, stronger metal-support interaction and more homogeneous metal dispersion, which altered the properties of catalyst towards an excellent catalytic performance. This study provides new perspective on the beneficial effect of P123-assisted impregnation method in the enhancement of catalytic performance of Ni/SBA-15 towards CO2 methanation.

Bimetallic catalysts for green methanol productionviaCO2and renewable hydrogen: a mini-review and prospects

This mini review discusses the recent advancements in the use of bimetallic catalysts for green methanol productionviaCO2hydrogenation.

Enhancement of catalytic performance and resistance to carbonaceous deposit of lanthanum (La) doped HZSM-5 catalysts for decomposition of methyl mercaptan

A series of rare earth elements (La, Ce, Pr, Nd, Sm, Y and Er) modified HZSM-5 catalysts were prepared and evaluated their catalytic performance for CH3SH decomposition. XRD, N2 adsorption-desorption, FT-IR, CO2-TPD and NH3-TPD were conducted to analyze the relationships between catalytic behaviors and their structural characteristics. It indicated that addition of rare earth metal could significantly improve activity and stability of HZSM-5 catalyst for CH3SH decomposition, and the best one was La(13)/HZSM-5 sample. CH3SH can be completely converted over La(13)/HZSM-5 at 450 °C compared to parent HZSM-5 at 600 °C. The optimal La(13)/HZSM-5 catalyst exhibited excellent stability without significant deactivation even after 80h time-on-stream test, while parent HZSM-5 was rapidly deactivated within 20 h under same reaction conditions. The excellent performance of La(13)/HZSM-5 can be attributed to its tunable acid-base properties, which not only promote adsorption and activation of CH3SH molecule but also effectively inhibit the formation of coke deposit. In addition, spent La(13)/HZSM-5 catalyst can be easily regenerated and no significant deactivation was observed during regeneration process.

Synergistic Enhancement in Catalytic Performance of Superparamagnetic Fe3O4@Bacilus subtilis as Recyclable Fenton-Like Catalyst

Novel well-defined superparamagnetic Fe3O4@Bacilus subtilis composite (Fe3O4@B. subtilis SPMC) was synthesized through a facile electrostatic attraction method and used as a recyclable heterogeneous Fenton-like catalyst. With the presence of H2O2, Fe3O4@B. subtilis SPMC can remove nearly 87% of the doxycycline at the initial concentration of 50 mg L−1, exhibiting enhanced Fenton-like catalytic performance than pristine Fe3O4. The mechanism study demonstrates the synergistic effect between Bacilus subtilis adsorption and Fenton-like ability of Fe3O4 dominates the enhancement for Fenton-like catalytic efficiency of Fe3O4@B. subtilis SPMC. The obtained composite shows excellent recycling ability, reusability, and stability, which pave a new way for future design on highly efficient Fenton-like catalyst for degradation of organic pollutants.

Cyclodextrin‐Based Polymer‐Assisted Ru Nanoparticles for the Aqueous Hydrogenation of Biomass‐Derived Platform Molecules

AbstractA green water‐soluble cyclodextrin polymer has been prepared through cross‐linking of β‐cyclodextrin (β‐CD) and polyethylene glycol diglycidyl ether (PEGDE). The as‐synthesized co‐polymer (PEG‐CD) showed an excellent ability to stabilize and constrain the size of Ru‐Nanoparticles in aqueous phase, as compared with other polymer stabilizer used in this work such as polyvinyl pyrrolidone (PVP−K30) and polyethylene glycol diglycidyl ether (PEGDE). The co‐ploymer PEG‐CD‐stabilizied Ru NPs have been found to be a highly efficient catalyst in the aqueous hydrogenation of levulinic acid into γ‐valerolactone under mild reaction condition. This catalyst system can be easily extended to the selective hydrogenation of other lignocellulose‐derived platform molecule including 5‐hydroxymethylfurfural, furfural, phenol, 2‐methoxy‐4‐methyl phenol and 2‐methoxy‐4‐ethyl phenol, etc. The further characterization analysis indicated that the small‐sized and highly dispersed Ru NPs (1.2‐2.0 nm) embedded in co‐ploymer PEG‐CD matrix were highly stable for the consecutive catalytic recycles. Additionally, the inclusion interaction of substrate molecules and β‐CD units within polymer matrix played a crucial role in the enhancement of catalytic performance.

Synergistic Hydrogenation over Palladium through the Assembly of MIL-101(Fe) MOF over Palladium Nanocubes.

Enhancing catalytic performance of metal nanoparticles is highly sought for many industrial catalytic processes. In this regard, assembly of crystalline porous super-tunable metal-organic frameworks (MOFs) around preformed metal nanoparticles is an attractive prospect as this strongly influences the activity of the entire nanoparticle surface. Herein, we assembled a MlL-101(Fe) MOF onto the Pd nanocubes and evaluated the catalytic properties of the hybrid material for the hydrogenation of the α,β-unsaturated carbonyl compounds cinnamaldehyde, crotonaldehyde, and β-ionone. Owing to the synergestic effects originating from the Lewis acid sites present on MOF and Pd active sites, striking improvements in the activities and selectivities were observed for the Pd⊂MIL-101(Fe) hybrid material. The turnover frequency (TOF) values increased up to roughly 20 fold and in all three studied substrates, C=C was preferentially hydrogenated compared to C=O. Furthermore, the Pd⊂MIL-101(Fe) catalyst was readily reusable and highly stable.

Synthesis of Ni–Ir Nanocages with Improved Electrocatalytic Performance for the Oxygen Evolution Reaction

Design and fabrication of inexpensive and efficient oxygen evolution reaction (OER) catalysts are of great importance for polymer electrolyte membrane water electrolyzers (PEMWEs). Although the best electrocatalyst is IrO2 for OER in the PEMWEs, the practical application of Ir has been impeded because of its high cost and limited activity. Herein, a galvanic replacement reaction mechanism was developed for the preparation of polycrystalline Ni–Ir nanocages (NCs) by using Ni nanoparticles as templates. The formation of Ni–Ir NCs achieves the enhancement of OER catalytic performance, accompanied by the reduction of Ir loading but significantly increasing the efficiency of Ir atoms. The as-prepared Ni2.53Ir NCs exhibit improved catalytic activity toward OER in acid solution, which requires only an overpotential of 302 mV to deliver a current density of 10 mA/cm2. At an overpotential of 300 mV, the Ir-based mass activity of Ni2.53Ir catalysts reaches 114.7 mA/mgIr, which is 2.1 times higher than that of comme...

Superior catalytic activity of Pt/carbon nanohorns nanocomposites toward methanol and formic acid oxidation reactions

Pt nanoparticle-loaded carbon nanohorns (Pt/CNHs) nanocomposites were synthesized by using formic acid as reducing agent at room temperature. Taking the advantage of the high surface area and excellent electronic conductivity, CNHs were used as support without any pretreatments for the enhancement of catalytic performance. By adjusting the feeding amount of H2PtCl6, the mass, size and distribution of Pt nanoparticles could be effectively controlled on CNHs. Compared with commercial Pt/C, the synthesized Pt/CNHs exhibit higher catalytic activity and improved long-term stability toward both methanol and formic acid oxidations. Among the Pt/CNHs, 13% wt. Pt/CNHs exhibit the best catalytic performances for the small size (2.4 nm) and uniform distribution of Pt NPs on CNHs. Our work reveals the superior catalytic performance of Pt/CNHs which may be a promising substitute for commercial Pt/C.

Two-dimensional iron-porphyrin sheet as a promising catalyst for oxygen reduction reaction: a computational study

The development of non-platinum (Pt) oxygen reduction reaction (ORR) catalysts with high activity and low cost is of great importance for large-scale commercialization of fuel cells. By means of density functional theory (DFT) computations, we theoretically identified that two-dimensional (2D) iron-porphyrin (Fe-Pp) sheet, in which the active Fe sites are distributed regularly and separately, is an appealing candidate. The pristine Fe-Pp sheet exhibits considerably high catalytic activity and four-electron selectivity for ORR. Especially, the adsorption of ORR intermediates on Fe-Pp sheet can be significantly weakened by the addition of axial cyanogen (CN) ligand, resulting in pronouncedly enhanced ORR activity. More interestingly, the d band center of CN attached Fe-Pp (Fe-Pp-CN) sheet can be further tuned by applying the external tensile or compressive strain, leading to an enhancement or suppression of ORR catalytic performance. In particular, under a small biaxial tensile strain of 2%, the ORR activity of Fe-Pp-CN sheet is even higher than that of Pt and reaches to the top of activity volcano. Our studies open new ways to design effective non-Pt ORR catalysts for fuel cell technology.

Enhancement of Catalytic Performance of α-dextranase from Chaetomium gracile Through Optimization and Suitable Shear Force

Dextran causes negative impact on the normal production of sugar industry. Traditional removal methods have many disadvantages. 6-alpha-d-glucan-6-glucanohydrolase (EC 3.2.1.11) from Chaetomium gracile without food safety concern could remove dextran, but it has low level of enzyme production. The present study aimed to improve α-dextranase activity to meet industry demand. Consequently, α-dextranase activity reached 242.8 U/mL when fermentation condition was 29 °C, pH 6.0 and 220 rpm. Meanwhile, ten glass beads were added to fermentation medium when fermentation time was 12 h, which improved enzyme activity by 135.5% with the highest activity. Purified α-dextranase exhibited excellent thermal stability and surfactants tolerance. α-Dextranase from C. gracile could remove dextran by 46.6% in mixed sugarcane juice and 14.1% in clarified sugarcane juice. It had similar dextran removal efficiency with commercial enzymes. These evaluations showed that α-dextranase had great potential in removing dextran in sugar industry.

Deposition of N-doped carbon layers inside acidic ZrSBA-15: significant enhancement of catalytic performance of Pd NPs toward benzyl alcohol aerobic oxidation

Palladium-based catalysts with equably distributions of surface functionalities are synthesized by anchoring palladium nanoparticles onto N-doped carbon layers stabilized by mildly acidic platelet ZrSBA-15 framework with short mesochannels. The catalysts were fully characterized by X-ray diffraction, N2 adsorption-desorption isotherms, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. Simultaneously, the Pd–NC–ZS catalysts exhibited the expectable activity in aerobic oxidation of benzyl alcohol with 82% conversion and absolute selectivity to benzaldehyde. Inappreciable loss in catalytic performance under solvent- and base-free conditions after ten times recycle demonstrated that there was strong interaction between palladium nanoparticles and the modified framework. Namely, a synergistic effect can be certified due to the surface acidic sites of ZrSBA-15 and N-doped carbon layers, which could strengthen the interaction between palladium nanoparticles and support, thus facilitating the anchoring and stabilization of palladium nanoparticles onto the pore walls of the NC–ZS.

Pushing Chemical Boundaries with N-Heterocyclic Olefins (NHOs): From Catalysis to Main Group Element Chemistry.

N-Heterocyclic olefins (NHOs) have gone from the topic of a few scattered (but important) reports in the early 1990s to very recently being a ligand/reagent of choice in the far-reaching research fields of organocatalysis, olefin and heterocycle polymerization, and low oxidation state main group element chemistry. NHOs are formally derived by appending an alkylidene (CR2) unit onto an N-heterocyclic carbene (NHC), and their pronounced ylidic character leads to high nucleophilicity and soft Lewis basic character at the ligating carbon atom. These olefinic donors can also be structurally derived from imidazole, triazole, and thiazole-based heterocyclic carbenes and, as a result, have highly tunable electronic and steric properties. In this Account, we will focus on various synthetic routes to imidazole-2-ylidene derived NHOs (sometimes referred to as deoxy-Breslow intermediates) followed by a discussion of the electron-donor ability of this structurally tunable ligand group. It should be mentioned that NHOs have a close structural analogy with Breslow-type intermediates, N-heterocyclic ketene aminals, and β-azolium ylides; while these latter species play important roles in advancing synthetic organic chemistry, discussion in this Account will be confined mostly to imidazole-2-ylidene derived NHOs. In addition, we will cover selected examples from the literature where NHOs and their anionic counterparts, N-heterocyclic vinylenes, are used to access reactive main group species not attainable using traditional ligands. Added motivation for these studies comes from the emerging number of low coordinate main group element based compounds that display reactivity once reserved for precious metal complexes (such as H-H and C-H bond activation). Moreover, NHOs are versatile precursors to new mixed element (P/C and N/C), and potentially bidentate, ligand constructs of great potential in catalysis, where various metal oxidation states and coordination environments need to be stabilized during a catalytic cycle. The most active area of recent growth for NHOs is their use as nucleophiles to promote efficient organocatalytic transformations, including transesterification, carbonyl reduction, and the conversion of CO2 into value added products. Polyesters have also been generated through the NHO-promoted ring-opening polymerization of lactones, and the highly tunable nature of NHO organocatalysts allows for the rapid screening and enhancement of catalytic performance. Therefore, the growing utility of NHOs in the realm of organic and polymer chemistry can be viewed as evidence of the widespread impact of N-heterocyclic olefins on the chemical community. It is hoped that through this Account others will join this flourishing research domain and that the rapid recent growth of NHO chemistry is sustained for the foreseeable future.

Improved CO2 Electroreduction Performance on Plasma-Activated Cu Catalysts via Electrolyte Design: Halide Effect

As a sustainable pathway for energy storage and to close the carbon cycle, CO2 electroreduction has recently gained significant interest. We report here the role of the electrolyte, in particular of halide ions, on CO2 electroreduction over plasma-oxidized polycrystalline Cu foils. It was observed that halide ions such as I– can induce significant nanostructuring of the oxidized Cu surface, even at open circuit potential, including the formation of Cu crystals with well-defined shapes. Furthermore, the presence of Cl–, Br–, and I– was found to lower the overpotential and to increase the CO2 electroreduction rate on plasma-activated preoxidized Cu catalyst in the order Cl– < Br– < I–, without sacrificing their intrinsically high C2–C3 product selectivity (∼65% total Faradaic efficiency at −1.0 V vs RHE). This enhancement in catalytic performance is mainly attributed to the specific adsorption of halides with a higher coverage on our oxidized Cu surface during the reaction, which have been previously report...

The evolution of titanium species in boron-containing Ti-MWW zeolite during post-treatment revealed by UV resonance Raman spectroscopy

Although the catalytic performance of boron-containing Ti-MWW (B-Ti-MWW) zeolite can be greatly improved by acid treatment before calcination, there are still issues about the definite role of acid treatment and the evolution of titanium species during post-treatment of B-Ti-MWW not very clear due to the lack of advanced technique to thoroughly characterize titanium species. Herein, powerful UV resonance Raman spectroscopy excited at 244 nm was used to address these issues for the first time. It was surprisingly found out that acid treatment of as-synthesized B-Ti-MWW not only removed about half of the absolutely dominant non-framework TiO6 species but also made the other part converted into framework TiO4 species, which has never been reported before. While acid treatment of directly calcined B-Ti-MWW made most of the dominant non-framework TiO6 species transformed into anatase TiO2. Importantly, among all treated samples, only those obtained from acid treatment of as-synthesized B-Ti-MWW and subsequent calcination showed catalytic activity in 1-hexene epoxidation, fully demonstrating that the remarkable enhancement of catalytic performance by acid treatment before calcination was actually ascribed to the transformation of inactive non-framework TiO6 species into active framework TiO4 species. These understandings would be very helpful for the study of boron-containing titanosilicate zeolites.

Fabrication of Supported Pd–Ir Mesocrystal Catalyst for Hydrogenation of 2-Ethylanthraquinone

Pd–Ir mesocrystals with rough surface and highly branched structure were synthesized through a facile co-reduction method. The morphology evolution shows the mesocrystals were formed by oriented attachment of nanoparticles, and abundant defects sites as well as synergetic effect between building units were formed during mesocrystals oriented attachment process. Therefore, the supported Pd–Ir mesocrystals show a significant enhancement in catalytic performance in hydrogenation of 2-ethylanthraquinone compared with conventional Pd–Ir nanoparticles. The high activity can be ascribed to high densities of defect sites in Pd–Ir MCs catalyst, which facilitated H2 activation. In addition, the geometric effect of Pd–Ir MCs catalyst was responsible for inhibiting further hydrogenation of eAQH2 to undesired consecutive byproducts.

Enhanced low-temperature NH3-SCR performance of MnOx/CeO2 catalysts by optimal solvent effect

A series of MnOx/CeO2 catalysts were prepared by modulating the solvents (deionized water (DW), anhydrous ethanol (AE), acetic acid (AA), and oxalic acid (OA) solution) with the purpose of improving the low-temperature NH3-SCR performance, broadening the operating temperature window, and enhancing the H2O+SO2 resistance. The synthesized catalysts were characterized by means of N2-physisorption, XRD, EDS mapping, Raman, XPS, H2-TPR, NH3-TPD, and in situ DRIFTS technologies. Furthermore, the catalytic performance and H2O+SO2 resistance were evaluated by NH3-SCR model reaction. The obtained results indicate that MnOx/CeO2 catalyst prepared with oxalic acid solution as a solvent exhibits the best catalytic performance among these catalysts, which shows above 80% NO conversion during a wide operating temperature range of 100–250°C and good H2O+SO2 resistance for low-temperature NH3-SCR reaction. This is related to that oxalic acid solution can promote the dispersion of MnOx and enhance the electron interaction between MnOx and CeO2, which are beneficial to improving the physicochemical property of MnOx/CeO2 catalyst, and further lead to the enhancement of catalytic performance and good H2O+SO2 resistance.

Metal-Nanoparticle-Catalyzed Hydrogen Generation from Formic Acid.

To meet the ever-increasing energy demand, the development of effective, renewable, and environmentally friendly sources of alternative energy is imperative. Hydrogen (H2) is a renewable, clean energy carrier, which exhibits a threefold energy density compared to gasoline; H2 is considered one of the most promising alternative energy carriers for enabling a secure, clean energy future. However, the realization of a hydrogen economy is restricted by several unresolved issues. Particularly, one of the most difficult challenges is the development of a safe, efficient hydrogen storage and delivery system. To this end, hydrogen storage techniques based on liquid-phase chemical hydrogen storage materials have become an attractive choice. Formic acid (FA) with a high volumetric capacity of 53 g H2/L demonstrates promise as a safe, convenient liquid hydrogen carrier. However, generating H2 from FA in a controlled manner at ambient temperature is still challenging, which primarily depends on the catalyst used. Hence, for practical purposes, it is imperative to develop high-performance heterogeneous catalysts for the dehydrogenation of FA. Ultrasmall metal NPs with a high surface-to-volume ratio and "clean" surface, and hence a high density of active sites exposed to reactants, are of significance for heterogeneous catalysis. However, the size of these "clean" ultrasmall metal NPs inevitably increase, and these particles undergo aggregation during synthesis and catalysis because of their high surface energy. The immobilization of metal NPs into appropriate support materials affords considerable advantages for catalytic applications, which not only offers spatial confinement to control the nucleation and growth of particles, but also prevents them from aggregation; hence, catalytic performance is significantly enhanced. In addition, the functionalization of the support with electron-rich groups is beneficial to the formation of intermediates for FA dehydrogenation, which in turn promotes the catalytic performance. In this Account, studies of hydrogen generation from FA using heterogeneous catalysts were reviewed, mainly focusing on the results reported by our group. By varying support materials (metal-organic frameworks, silica, graphene, and porous carbons) and synthetic strategies, a wide range of highly active metal NP catalysts for efficient H2 generation from FA under mild conditions were developed. In addition, the design and synthetic strategies were described, by which the size and composition of the NPs, as well as the well-defined NPs-support interactions, can be controlled for the enhancement of catalytic performance for the FA dehydrogenation. Furthermore, the performance of the prepared catalysts for the effective release of H2 from FA for the purpose of liquid-phase chemical hydrogen storage was discussed. Finally, the challenges, expected improvements, and future opportunities in this research area were summarized.

Effects of alkali-treated hierarchical HZSM-5 zeolites on the production of aromatic hydrocarbons from catalytic fast pyrolysis of waste cardboard

The effects of hierarchical porous HZSM-5 zeolites on improving the yield of aromatic hydrocarbons during catalytic fast pyrolysis (CFP) of waste cardboard (WCB) were investigated. Desilicated HZSM-5 zeolites were successfully prepared by alkaline treatment using NaOH solution with different concentrations (0.1M–0.7M). A Py-GC/MS apparatus was adopted to carry out the CFP experiments. Results showed that under mild alkaline treatment (NaOH concentration ≤0.3M), the micropores and crystallinity of HZSM-5 were preserved, while the mesopores and weak acid sites increased. The desilicated HZSM-5 zeolites increased the total yield of pyrolytic products from WCB. With regard to the product distribution, carbon yield of aromatics increased dramatically, while that of sugars, carbonyl compounds and other oxygenates decreased obviously. Specifically, HZSM-5 treated by 0.3M NaOH solution (HZ-0.3M) was proved to be the most effective catalyst, resulting in a 44% increase of carbon yield of aromatics and an 82% increase of carbon yield of BTX (benzene, toluene and xylenes) comparing to the parent HZSM-5. In addition, the amount of coke deposited on HZ-0.3M decreased by 29% compared to that on the parent HZSM-5. The retained micropores and the created mesopores of desilicated HZSM-5 zeolites contributed to the enhancement of catalytic performance. However, harsh alkaline treatment of HZSM-5 zeolites (NaOH concentration ≥0.5M) resulted in the grave collapse of zeolitic crystallinity and the obvious loss of micropores. As a result, the catalytic activities of HZSM-5 zeolites had been weakened.

Enhancing both selectivity and coking-resistance of a single-atom Pd1/C3N4 catalyst for acetylene hydrogenation

Selective hydrogenation is an important industrial catalytic process in chemical upgrading, where Pd-based catalysts are widely used because of their high hydrogenation activities. However, poor selectivity and short catalyst lifetime because of heavy coke formation have been major concerns. In this work, atomically dispersed Pd atoms were successfully synthesized on graphitic carbon nitride (g-C3N4) using atomic layer deposition. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) confirmed the dominant presence of isolated Pd atoms without Pd nanoparticle (NP) formation. During selective hydrogenation of acetylene in excess ethylene, the g-C3N4-supported Pd NP catalysts had strikingly higher ethylene selectivities than the conventional Pd/Al2O3 and Pd/SiO2 catalysts. In-situ X-ray photoemission spectroscopy revealed that the considerable charge transfer from the Pd NPs to g-C3N4 likely plays an important role in the catalytic performance enhancement. More impressively, the single-atom Pd1/C3N4 catalyst exhibited both higher ethylene selectivity and higher coking resistance. Our work demonstrates that the single-atom Pd catalyst is a promising candidate for improving both selectivity and coking-resistance in hydrogenation reactions.