The Influence of Reaction Conditions on Selective Acetylene Hydrogenation Over Sol Immobilization Prepared AgPd/Al2O3 Catalysts

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...

Selective Hydrogenation of Acetylene over a MoP Catalyst

Selective hydrogenation of acetylene over Pd/β-Mo2C catalyst: Experimental and theoretical studies

The selective hydrogenation of acetylene to remove trace acetylene in ethylene plays a significant role in the ethylene polymerization industry. Herein, boron nitride (BN) was selected for encapsulating Pd nanoparticles to prepare a catalyst with atomic Pd sites exposed by a simple inorganic precursor‐based strategy. This atomically exposed Pd catalyst favors the desorption of ethylene kinetically instead of further hydrogenation, which is the key for improving the selective hydrogenation of acetylene. With only atomic Pd exposure, the Pd@BN‐0.5 catalyst reached 94% ethylene selectivity when acetylene conversion was 100% in a pure acetylene environment. More importantly, this atomically exposed Pd catalyst also showed an ethylene selectivity of 84.7% in ethylene‐rich feed, which is the simulated environment for industrial production. Finally, this atomic exposure strategy was extended to PdAg@BN, where 96.9% ethylene selectivity in a pure acetylene environment and 88.7% ethylene selectivity in an ethylene‐rich environment were obtained.

Ligand screening for palladium nanocatalysts towards selective hydrogenation of alkynes

Experimental study and modeling of the liquid phase hydrogenation of acetylene

Synthesis of novel Ag-modified Pd-supported mesoporous carbon nitride for selective hydrogenation of acetylene with an excellence ethylene selectivity

Selective hydrogenation of acetylene on Pd/SiO2 in bulk liquid phase: A comparison with solid catalyst with ionic liquid layer (SCILL)

Selective hydrogenation of acetylene on carbon-encapsulated Ni-Co-Cu trimetallic nanoparticles: Synergizing electronic effects and spatial confinement

In order to achieve considerable CO2 reductions there is an urgent need to develop alternative sustainable processes based on bio-based feedstock and renewable energy. The energy sector is currently in a transition towards cost competitive energy generation from renewable sources. Where the availability of cheap electricity presents an opportunity to electrify the chemical industry, as it can benefit from the progressive decarbonisation of the energy sector.1 Furthermore, the shift towards bio-based feedstock represents the largest abatement potential for CO2 emissions.2 Valeric acid (pentanoic acid) is currently produced via hydroformylation (oxo-process) of 1-butene followed by oxidation of valeraldehyde to the valeric acid. Levulinic acid, or 4-oxopentanoic acid, is one of the renewable platform chemicals and can be derived from lignocellulosic biomass via acid catalysed hydrolysis. Typically, levulinic acid is reduced in one step to valeric acid utilizing lead electrodes, with γ-valerolactone (gVL) being a minor by-product.3 Recently, we have demonstrated the viability of other cathode materials (indium, cadmium and zinc). Where indium exhibited superior selectivity, as no formation of the side product gVL has been detected.4 Although the electrochemical ketone reduction to the methylene functionality of levulinic acid and similar compounds is known for more than 100 years, no study on the influence of reaction conditions is reported to the best of our knowledge. Therefore, to come towards an optimal electrochemical process design, it is vital to understand the influence of reaction parameters. We therefore focused in our study on the influence of reaction conditions next to the applicability of other cathode materials. Typical high overpotential electrodes (In, Pb, Cd and Hg) exhibited the highest selectivity and activity towards VA, whereas Pt/C showed the highest selectivity and activity towards gVL. The influence of acidity and temperature on conversion and selectivity was studied for In, Pb and Cd together with the influence of anode material on the design of the electrochemical reactor. Interestingly we found that the selectivity is highly dependent of the acidity (pH) and the nature of the cathode material (see Figure). The increasing selectivity towards VA at decreasing pH is remarkable considering that lactonization of 4-hydroxy-pentanoic acid to gVL is catalyzed under acidic conditions. Another interesting aspect is the increasing conversion of LA at decreasing pH and thus increasing suppression of the electrochemical evolution of hydrogen.We tentatively explain these observed phenomena by an increased coverage of the electrode surface by protonated levulinic acid which in turn influences the activity and selectivity of the process.[1] DECHEMA, Low carbon energy and feedstock for the European chemical industry (2017).[2] Stork M., de Beer J., Lintmeijer N., den Ouden B., Chemistry for Climate: Acting on the need for speed Roadmap for the Dutch Chemical Industry towards 2050, February 2018.[3] Tafel J., Emmert B., Zeitschrift für Elektrochemie 17 (1911), 569-572; Chum H. L., Electrochemistry Applied to Biomass, October 1980 – September 1981, SERI, 1982; Nilges P., dos Santos T.R., Harnisch F., Schröder U, Energy Environ. Sci. 5 (2012), 5231-5235; Xin L., Zhang Z., Qi J., Chadderdon D.J., Qiu Y., Warsko K.M. Li W., ChemSusChem 6 (2013), 674- 686; Dos Santos T.R., Nilges P., Sauter W., Harnisch F., Schröder U., RSC Adv. 5 (2015), 26634-26643.[4] Bisselink R.J.M., Crockatt M., Zijlstra M., Bakker I.J., Goetheer E., Slaghek T.M., van Es D.S., ChemElectroChem 6 (2019), 3285-3280. Figure 1

The selective hydrogenation has attracted increasing attention to chemists for the production of value‐added products in chemical industry. Over the past several decades, substantial effort has been devoted to the design of catalyst for the selective hydrogenation of light alkynes and α, β‐unsaturated aldehydes, two classic cases for selective hydrogenation in chemical industry. Despite the great progress, it remains great challenges to achieve the selective hydrogenation because the desired products are generally thermodynamically unfavored. Here, we summarize the recent advances on selective hydrogenation using noble metal nanocrystals, with an emphasis on the surface engineering of noble metal nanocrystals for the selective hydrogenation of light alkynes and α, β‐unsaturated aldehydes. We will highlight the strategies for surface engineering, the advanced techniques for characterizations, as well as mechanism studies. We hope this review will promote chemists to develop efficient and robust catalysts for selective hydrogenation.

Selective hydrogenation of acetylene over Pd/Fiberglass catalysts: Kinetic and isotopic studies

Effect of Ag addition on the properties of Pd–Ag/TiO2 catalysts containing different TiO2 crystalline phases

The selective hydrogenation of acetylene to ethylene in an ethylene-rich gas stream is an important process in the chemical industry. Pd-based catalysts are widely used in this reaction due to their excellent hydrogenation activity, though their selectivity for acetylene hydrogenation and durability need improvement. Herein, the successful synthesis of atomically dispersed Pd single-atom catalysts on nitrogen-doped graphene (Pd1 /N-graphene) by a freeze-drying-assisted method is reported. The Pd1 /N-graphene catalyst exhibits outstanding activity and selectivity for the hydrogenation of C2 H2 with H2 in the presence of excess C2 H4 under photothermal heating (UV and visible-light irradiation from a Xe lamp), achieving 99% conversion of acetylene and 93.5% selectivity to ethylene at 125 °C. This remarkable catalytic performance is attributed to the high concentration of Pd active sites on the catalyst surface and the weak adsorption energy of ethylene on isolated Pd atoms, which prevents C2 H4 hydrogenation. Importantly, the Pd1 /N-graphene catalyst exhibits excellent durability at the optimal reaction temperature of 125 °C, which is explained by the strong local coordination of Pd atoms by nitrogen atoms, which suppresses the Pd aggregation. The results presented here encourage the wider pursuit of solar-driven photothermal catalyst systems based on single-atom active sites for selective hydrogenation reactions.

Five hundred ppm Pd/CeO2 catalyst was prepared and evaluated in selective hydrogenation of acetylene in large excess of ethylene since ceria has been recently found to be a reasonable stand-alone catalyst for this reaction. Pd/CeO2 catalyst could be activated in situ by the feed gas during reactions and the catalyst without reduction showed much better ethylene selectivity than the reduced one in the high temperature range due to the formation of oxygen vacancies by reduction. Excellent ethylene selectivity of ∼100% was obtained in the whole reaction temperature range of 50°C–200°C for samples calcined at temperatures of 600°C and 800°C. This could be ascribed to the formation of PdxCe1−xO2−y or Pd-O-Ce surface species based on the X-ray diffraction and X-ray photoelectron spectroscopy results, indicating the strong interaction between palladium and ceria.