Experimental study and modeling of the liquid phase hydrogenation of acetylene

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...

Catalyst deactivation in liquid- and gas-phase hydrogenation of acetylene using a monolithic catalyst reactor

Selective Hydrogenation of Acetylene over a MoP Catalyst

The liquid-phase catalytic hydrogenation of acetylene into ethylene in the presence of CO over palladium supported on the graphite-like material Sibunit has been investigated. Carbon monoxide is an effective modifier of the selective hydrogenation process, exerting its effect by competing with acetylene and ethylene for chemisorption sites on the palladium surface. Under the optimum conditions (T = 90°C; N-methylpyrrolidone solvent; feed consisting of 2 vol % C2H2, 90 vol % H2, and He balance), the introduction of 2 vol % CO ensures a high ethylene selectivity of 89.6 ± 1.5% at an acetylene conversion of 95.8 ± 1.3%, with the acetylene converted into hydrooligomers taken into account.

The results of studies on selective hydrogenation of acetylene to ethylene over bimetallic palladium-containing catalysts were summarized. Regular and specific features of the catalyst action in gas-phase hydrogenation of traces of acetylene in the acetylene-ethylene mixture produced by pyrolysis of petroleum feedstock, as well as in liquid-phase hydrogenation of mixtures enriched in acetylene and hydrogen were analyzed. The advantages of ethylene production by liquid-phase hydrogenation of acetylene were shown, and ways of increasing the selectivity to ethylene in this process were considered.

В представленном обзоре обобщены результаты исследований, посвященных селективному гидрированию ацетилена в этилен на биметаллических палладиевых катализаторах. Проанализированы общие закономерности и особенности их действия в газофазном гидрировании следов ацетилена в ацетилен-этиленовой смеси, получаемой пиролизом нефтяного сырья, а также в процессе жидкофазного гидрирования смесей, обогащенных ацетиленом и водородом. Показаны преимущества получения этилена путем гидрирования ацетилена в жидкой фазе и рассмотрены способы повышения селективности этого процесса.

Selective hydrogenation of acetylene to ethylene while avoiding over-hydrogenation into ethane is challenging for polymer industry. For highly steerable catalyst design of Metal-MoS2, we reported a few-layer nano-MoS2 supported Pd catalyst, in which the support was prepared by the exfoliation method of bulk molybdenum disulfide (MoS2) in formamide solution. The results from TEM, SAED, AFM and Raman spectra analysis confirmed that the few-layer nano-MoS2 was produced successfully. The XPS result indicates Pd charge transferred to MoS2, proving strong Pd-MoS2 interactions. Pd/nano-MoS2 provided a good catalytic performance for the hydrogenation of acetylene to ethylene, and the ethylene selectivity can reach up to 75% while acetylene conversion can achieve nearly 100%. Comparing with the commercial 5% Pd/C catalyst reported at similar conditions, the Pd/nano-MoS2 synthesized in this study presents better activity and selectivity. In all, this work shows potential application of MoS2 nanosheets used as catalyst support to achieve selective steerable reactions.

The selective hydrogenation of acetylene is usually a gas-phase reaction. In this work, a liquid phase was introduced as a selective solvent to improve the selectivity to ethylene by coupling absorption to the reaction. The catalyst was 0.01% Pd supported on a low surface area silica. N-methyl-2-pyrrolidone (NMP) was used as a selective solvent, and decane was used as a nonselective solvent for comparison. The liquid-phase hydrogenation was carried out in a stirred flat bottom flask operated in gas continuous and liquid batch mode, and the gas-phase hydrogenation was carried out in a fixed bed reactor. The selectivity to ethylene in the gas-phase hydrogenation was 50–70%. In contrast, the highest selectivity to ethylene in the NMP liquid-phase hydrogenation was increased to 96%, while in decane it had the same value as in the gas phase. In NMP, a low reaction temperature below 80 °C did not give a high selectivity to ethylene because the relatively high ethylene solubility in NMP led to deep hydrogenation and the high acetylene solubility caused more oligomerization. Good catalyst stability was obtained under the optimized conditions of a relatively low space velocity, H2:C2H2 ratio above 10, and reaction temperature above 80 °C. Significant deactivation also occurred in NMP under other conditions due to oligomerization.

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

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

The nature of modifying effect of gallium on Pd-Ga/Al2O3 catalyst for liquid-phase selective acetylene hydrogenation

Ligand screening for palladium nanocatalysts towards selective hydrogenation of alkynes

In this research, a heterogeneous Nano-Structured functionalized SBA-15 metformin palladium composite catalyst is reported for the selective hydrogenation of alkynes. In the first place, A series of the heterogeneous mesoporous SBA-15 metformin palladium catalyst were prepared and afterwards the condition and the ratio of used materials were optimized to give rise a suitable high performance catalyst. The final nano-structured catalyst was characterized by X-ray powder diffraction, BET surface area, FT-IR spectrophotometer, Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) and served in partial hydrogenation of different alkynes, with high selectivity and high yield. The liquid phase hydrogenation was conducted under mild condition of room temperature and atmospheric pressure. The reactions were monitored every half an hour by gas chromatography and all of them were completed during 4-6 hours. The products were characterized by 1H-NMR, 13C-NMR, FT-IR, and Mass Spectrometry (MS) that strongly confirmed the (Z)-double bond configuration of produced alkenes. This prepared catalyst is competitive with the best palladium catalysts known for the selective liquid phase hydrogenation of alkynes and can be easily recovered and regenerated with keeping high activity and selectivity over multiple cycles with a simple regeneration procedure.

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

The structure of Ga2O3–Al2O3 supports and Pd/Ga2O3–Al2O3 catalysts and the performance of these catalysts in liquid-phase acetylene hydrogenation have been investigated. The deposition of Ga(NO3)3 onto Al2O3 by impregnation followed by calcination of the impregnated support at 600°C yields γ-Ga2O3–Al2O3 solid solutions containing up to 50 wt % Ga2O3. X-ray diffraction characterization of model palladium catalysts and their temperature-programmed reduction with hydrogen have demonstrated that, while palladium in Pd/Ga2O3 is in the form of a Pd2Ga alloy, in the Pd/γ-Ga2O3–Al2O3 catalyst there is no direct interaction between PdО and Ga2O3 particles and palladium is in the monometallic state. The introduction of 10–20 wt % gallium oxide into Al2O3 lowers the activity of the supported palladium catalyst relative to that of the initial Pd/Al2O3 but increases the ethylene yield by enhancing the ethylene formation selectivity.