Partial Hydrogenation Reaction Research Articles

Nanoporous Carbon-Supported Bimetallic (Ni, Cu, and Fe)-Mo Catalysts for Partial Hydrogenation of Biodiesel.

Upgrading biodiesel or hydrogenated fatty acid methyl esters (H-FAMEs) by partial hydrogenation is a second-generation biofuel with high specific fuel characteristics, such as superior cold flow properties, higher oxidative stability, and lower hazardous gas emissions, allowing this biofuel to provide excellent fuel properties, over conventional biodiesel. This study assessed the potential of using nanoporous carbon produced from cattail leaves (CL) as an alternative catalyst support. We synthesized various catalysts including monometallic Mo/NPC, Ni/NPC, Ce/NPC, and Fe/NPC catalysts, as well as bimetallic molybdenum-based catalysts doped with nickel, copper, or iron for the partial hydrogenation of soybean biodiesel. The NPC support demonstrated a surface area (S BET) of approximately 1,323 m2g-1, which greatly increases the catalytic activity through the efficient dispersion of catalyst active sites. The partial hydrogenation reaction of soybean FAME over the MoNi/NPC catalyst obtained the highest catalytic activity with enhanced oxidation stability from 3 to 14 h, and the cloud point and pour point increased from 2 to 13 °C and -1 to 10 °C, respectively. Hence, the selection of catalysts is crucial due to their impact on the feasibility of the process and its economic viability. This article focuses on highlighting the effectiveness of a highly promising catalyst for partial hydrogenation as well as examining the variables that influence the primary reaction pathway.

Unique Possibilities of Dynamic Metal–Polymer Interactions in Selective Hydrogenation

AbstractRationally designed polymers can function as supports or promoters for metal catalysts, imparting distinct catalytic properties in selective hydrogenation. With strongly metal–ligating functional groups, mobile polymer chains can spontaneously decorate the metal catalyst surfaces under mild conditions, forming stable metal–polymer interfaces. We have termed this phenomenon ‘dynamic metal–polymer interaction (DMPI),’ which can be roughly considered as an organic version of the strong metal–support interaction (SMSI) concept. The polymer chains that dynamically interact with the metal surface can control the adsorption of reactants and products through competitive adsorption, significantly improving selectivity and catalyst stability. One of the remarkable advantages of using polymers as catalytic materials is that their molecular structures, such as molecular weight, crystallinity, and chemical functionality, can be tailored using rich organic chemistry. This, in turn, allows us to precisely tune the metal–polymer interactions and catalytic properties. In this Concept, we will discuss how metal–polymer interfaces can be designed and utilized for selective hydrogenation, with a particular emphasis on the industrially relevant acetylene partial hydrogenation reaction.

Hard kinetic modeling of the industrial reaction of hydrogenation of soybean oil optimized by heuristic problem-solving techniques

Partial hydrogenation of vegetable oils is an important process for generating fats with particular characteristics. In this study, the hard kinetic modeling of the nickel-catalyzed soybean oil hydrogenation reaction was optimized by three algorithms considering five reaction mechanisms. In three mechanisms, it was considered to have a formation of half-hydrogenated intermediate compounds, and two did not consider this possibility. The Particle Swarm Optimization (PSO) algorithm allowed for achieving lower errors between the experimental and modeled values compared to the Simulated Annealing (SA) and Sequential Simplex (SP) algorithms for the five evaluated reaction mechanisms. In addition, the optimized apparent rate constants values indicated that in these reactional conditions, the industrial reaction mechanism of hydrogenation follows some preferred reaction pathways, such as a preliminary isomerization of cis to trans fatty acids to be then hydrogenated to other fatty acids less unsaturated. These optimization algorithms proved to be efficient tools for investigating the kinetics of the partial hydrogenation reaction of soybean oil and offer promising perspectives for other industrial processes.

Dynamics of Pd Subsurface Hydride Formation and Their Impact on the Selectivity Control for Selective Butadiene Hydrogenation Reaction.

Structure-sensitive catalyzed reactions can be influenced by a number of parameters. So far, it has been established that the formation of Pd-C species is responsible for the behavior of Pd nanoparticles employed as catalysts in a butadiene partial hydrogenation reaction. In this study, we introduce some experimental evidence indicating that subsurface Pd hydride species are governing the reactivity of this reaction. In particular, we detect that the extent of formation/decomposition of PdHx species is very sensitive to the Pd nanoparticle aggregate dimensions, and this finally controls the selectivity in this process. The main and direct methodology applied to determine this reaction mechanism step is time-resolved high-energy X-ray diffraction (HEXRD).

Partial Hydrogenation of Soybean and Waste Cooking Oil Biodiesel over Recyclable-Polymer-Supported Pd and Ni Nanoparticles

Biodiesel obtained through the transesterification in methanol of vegetable oils, such as soybean oil (SO) and waste cooking oil (WCO), cannot be used as a biofuel for automotive applications due to the presence of polyunsaturated fatty esters, which have a detrimental effect on oxidation stability (OS). A method of upgrading this material is the catalytic partial hydrogenation of the fatty acid methyl ester (FAME) mixture. The target molecule of the partial hydrogenation reaction is monounsaturated methyl oleate (C18:1), which represents a good compromise between OS and the cold filter plugging point (CFPP) value, which becomes too high if the biodiesel consists of unsaturated fatty esters only. In the present work, polymer-supported palladium (Pd-pol) and nickel (Ni-pol) nanoparticles were separately tested as catalysts for upgrading SO and WCO biodiesels under mild conditions (room temperature for Pd-pol and T = 100 °C for Ni-pol) using dihydrogen (p = 10 bar) as the reductant. Both catalysts were obtained through co-polymerization of the metal containing monomer M(AAEMA)2 (M = Pd, Ni; AEEMA− = deprotonated form of 2-(acetoacetoxy)ethyl methacrylate)) with co-monomers (ethyl methacrylate for Pd and N,N-dimethylacrilamide for Ni) and cross-linkers (ethylene glycol dimethacrylate for Pd and N,N’-methylene bis-acrylamide for Ni), followed by reduction. The Pd-pol system became very active in the hydrogenation of C=C double bonds, but poorly selective towards the desirable C18:1 product. The Ni-pol catalyst was less active than Pd-pol, but very selective towards the mono-unsaturated product. Recyclability tests demonstrated that the Ni-based system retained its activity and selectivity with both the SO and WCO substrates for at least five subsequent runs, thus representing an opportunity for waste biomass valorization.

Stitching up the Belt[n]arenes

A synthetic strategy reported recently in the Journal of the American Chemical Society by Wang and coworkers, who used laser irradiation in the final key step of the synthesis, has led to the formation of highly strained belt[8]arene derivatives. This breakthrough could open doors to more controlled and precise syntheses of zigzag carbon nanotubes.

The structures, stabilities and electronic properties of PdnB (n = 1–10) clusters

Recently experiments proved that Pd catalyst modified with subsurface B atoms had ultra selectivity in selected partial hydrogenation reaction. To make clear the effect of interstitial B atom, the structures, stabilities and electronic properties of PdnB (n = 1–10) clusters have been analyzed by density functional theory. B atom takes residence in octahedral positions of the Pdn, which just is interstitial lattice sites of Pd catalyst. B atom is easily incorporated into when Pd:B ≧ 6:1. The magic numbers of PdnB(n = 1–10) clusters is 6. The Pd6B happens to be the unit structure of Pd-B catalyst. Based on the analysis of structure parameters, electronic properties and d-band of Pd6B, we conclude that the improvement of Pd catalyst by interstitial B atom is mainly due to lattice expansion, strong electronic effect and hindering interstitial H atom.

Highly selectivity catalytic hydrogenation of acetylene on Al2O3 supported palladium-imidazolium based ionic liquid phase

Designing the electron-rich palladium active site is of great importance to enhance the selectivity of ethylene in acetylene semi-hydrogenation. In this work, ionic liquids, the effective electronic modifier, were mingled with palladium solution to be immobilized on Al2O3 by incipient impregnation method. X-ray photoelectron spectra characterization was conducted to characterize the structure of catalysts, suggesting that some ionic liquids can form unique carbene structure. The catalytic results showed that those immobilized ionic liquids that can form unique carbene structure exhibited much higher selectivity of ethylene than those cannot. The above results were obtained because carbene can donor the electron to palladium, enriching the electron density of palladium and therefore facilitating the desorption of ethylene. The findings of the unique carbene structure derived from ionic liquids in this work provide an efficient strategy to design the catalyst to improve the selectivity of the intermediate in other partial hydrogenationreactions.

Continuous flow catalytic partial hydrogenation of hydrocarbons and alcohols over hybrid Pd/ZrO2/PVA wall reactors

• Wall reactors comprising Pd nanoparticles into an hybrid zirconia / polyvinyl alcohol layer are prepared. • Wall reactors are used in the catalytic partial hydrogenation reaction of unsaturated hydrocarbons in the liquid phase. • Monoenes are obtained with excellent selectivity for dienes and alkynes, respectively, under continuous flow conditions. • Minimal amounts of catalyst and mild reaction conditions are required in hydrophilic solvents. • Neither metal leaching nor need of additives is observed. Catalytic hydrogenation reactions of functionalized hydrocarbons are of utmost interest in the fine-chemicals industry. Current hurdles relate to catalyst selectivity and stability, which often require use of sophisticated catalysts and/or the use of considerable amount of toxic additives. For practical applications, processes intensification would also be needed in terms of reagents/catalyst separation, improved space-time-yield productivity. We have shown that catalytic wall reactors comprising a zirconia/polyvinyl alcohol/Pd hybrids layered onto an inert solid support can be easily engineered and used in the liquid phase continuous flow partial hydrogenation reaction of alkenes and alkynes. Films of typical 0.5–1.5 nm thickness and containing ca. 10% wt palladium nanoparticles of 3.6 ± 0.9 nm size (TEM) provided good conversion and selectivity (88–99%) in the partial hydrogenation of 1,5- cyclooctadiene and 3-hexyn-1-ol over ca. 1 mg hybrid catalyst, under very mild flow conditions, i.e. residence times 150–180 s and room temperature. The catalysts showed remarkable resistance over prolonged time on stream, with neither metal leaching detected nor additives or regeneration steps required for use in hydrophilic solvents.

Synthesis of kemiri sunan (reutealis trisperma (blanco) airy shaw) H-FAME through partially hydrogenation using Ni/C catalyst to increase oxidation stability

Hydrogenated FAME (H-FAME) synthesis of Kemiri Sunan (Reutealis Trisperma (Blanco) Airy Shaw) using Nickel/Carbon catalyst is one of the methods to improve the oxidation stability of Kemiri Sunan biodiesel. The partial hydrogenation reaction breaks the unsaturated bond on FAME (Fatty Acid Methyl Ester), which is a key component of the determination of oxidative properties. Changes in FAME composition by partial hydrogenation reaction are predicted to change the oxidation stability, so it does not cause deposits that can damage the diesel engine injection system, pump system, and storage tank. Partial hydrogenation reaction is under conditions of 120 °C and 6 bars with 100:1, 100:5, 100:10 % wt catalyst in the stirred semi-batch autoclave reactor. H-FAME synthesis with 100:5 % wt Ni/C catalyst can decrease the iodine number which is the empirical measure of the number of unsaturated bonds from 166.77 to 155.64 (g-I2/100 g) with an increase of oxidation stability from 650 to 665 minutes.

Application of modified microwave polyol process method on NiMo/C nanoparticle catalyst preparation for hydrogenated biodiesel production

The development of renewable feedstock-based diesel fuel is start to come up as the solution of national energy problem. However, the thermal and oxidative stability of biodiesel is not good enough. As a result, biodiesel can only be added to commercial diesel fuel as a mixture with concentration under 20%. To get better thermal and oxidation stability, partial hydrogenation process is applied to biodiesel caused the increase of monounsaturated FAME structure. Activated carbon supported NiMo nanocrystal catalyst was used in partial hydrogenation reaction to get high activity, conversion, and selectivity. In this research, NiMo/C catalyst was prepared by modified microwave polyol process method, which is provided a rapid heating and cooling process. This method can produce nano-sized NiMo/C catalyst with short time and low energy consumption. NiMo/C catalyst produced in this research has 285.85 m2/gram surface area and 77.79 nm crystal size, resulting 20.41% conversion and 8.87% selectivity of biodiesel product. Further research should be conducted to obtain optimum condition.

Effectiveness of activated mistalea (Viscum album L.) as a heterogeneous catalyst for biodiesel partial hydrogenation

Abstract In the present work, usage of the carbonized mistalea (viscum album L.) as an eco-friendly, cheap and easy prepeared heterogeneous catalyst is proposed for partial hydrogenation reaction of biodiesel. The catalyst produced by carbonization process was carefully characterized by FTIR, SEM and BET methods and also elemental analysis. Effectiveness of the obtained catalyst was investigated by using for the partial hydrogenation of corn-oil biodiesel. The biodiesel product after partial hydrogenation has been investigated by means of Fatty acid methyl esters, oxidation stability, pour point and cloud point. Even if a small amount of the catalyst was used, it showed high catalytic activity for the partial hydrogenation reaction. As a result it can be reccomended as a potential catalyst for the similar studies in this area.

Unconventional Pd@Sulfonated Silica Monoliths Catalysts for Selective Partial Hydrogenation Reactions under Continuous Flow

AbstractDoubly functionalized, hierarchical‐porosity silica monoliths were synthesized by postgrafting of sulfonic groups and in situ growth of Pd nanoparticles in that order. PdNP of 3.1 nm size located in the mesopores of the material showed to be evenly distributed within 4.6 % wt Pd monoliths. The system was explored in the continuous‐flow, catalytic partial hydrogenation reaction of 3‐halogeno‐nitrobenzenes and 3‐hexyn‐1‐ol in the liquid phase, showing remarkable conversion, selectivity, and resistance under very mild conditions.

When the nature of surface functionalities on modified carbon dominates the dispersion of palladium hydrogenation catalysts

Commercial carbon nanofibers with different graphitic structure and commercial multiwall carbon nanotubes (CNT) were chemically modified in order to introduce specific alkyl ligands on their surface. Palladium catalysts have been prepared using these modified supports and subsequently tested in the partial hydrogenation of 1,3-butadiene under conditions of excess hydrogen. Herein, we used thermogravimetry (TG), temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and nitrogen adsorption at 77K techniques in order to characterize both supports and catalysts. We focus on testing the effects of support surface functionalities either on morphology of supported palladium (Pd) nanoparticles (NPs) or on their catalytic performances. High selectivity to butenes was obtained with the catalysts prepared over supports containing alkyl chains, while over-hydrogenation to butane took place over oxygen-containing functional groups. Nicely the catalysts with modified supports minimize the secondary hydrogenation of butenes even at high conversions. Therefore, Pd NPs on modified nano-carbon catalysts may open up more opportunities to optimize the activity and the selectivity for partial hydrogenation reactions.

Continuous-flow processes for the catalytic partial hydrogenation reaction of alkynes.

The catalytic partial hydrogenation of substituted alkynes to alkenes is a process of high importance in the manufacture of several market chemicals. The present paper shortly reviews the heterogeneous catalytic systems engineered for this reaction under continuous flow and in the liquid phase. The main contributions appeared in the literature from 1997 up to August 2016 are discussed in terms of reactor design. A comparison with batch and industrial processes is provided whenever possible.

Low trans-isomers formation in the aqueous-phase Pt/TPPTS-catalyzed partial hydrogenation of methyl esters of linseed oil

Very low formation of both undesired products namely trans-C18:1 esters and the fully saturated methyl stearate (MS) with high catalytic activities (TOF=6820h−1) under mild reaction conditions have been achieved by water-dispersible platinum(0) nanoparticle catalysts stabilized by TPPTS ligands and the zwitterionic phospholipid surfactant lecithin in the partial hydrogenation of polyunsaturated methyl esters of linseed oil (MELO) into their monounsaturated counterparts in aqueous/organic micellar reactors. The reaction rate was independent of the stirring rate ensuring that mass transfer was not rate determining. The apparent activation energy of the Pt/TPPTS catalyst was calculated and amounts a low value of 17.8kJ/mol. Employing Pt/TPPTS catalysts the starting material MELO possessing an iodine value (IV) of 202 was reduced to IV=85 and contained only 2.4mol% of trans-C18:1 esters. In contrast, in the traditional industrial partial hydrogenation process of soybean oil possessing an IV of 130 reduced over commercial Ni-based catalyst to IV=80 the trans-fats content was∼30mol% whereas with a further reduction to IV=70 to produce all-purpose shortenings the trans-fats level reached a higher value of∼45mol%. In the aqueous-phase catalysis, in the range of 55–70 IVs for the hydrogenated products of MELO the Pt/TPPTS catalysts gave the least amount of trans-C18:1 esters followed by Rh/TPPTS and then by Pd/TPPTS complexes. Interestingly, with Pt/TPPTS catalysts the formation of MS was very low compared with Pd/TPPTS and Rh/TPPTS systems. Over highly active heterogeneous Pt/Al2O3 (5wt.%) catalysts the formation of trans-C18:1 esters was low whereas the content of MS was high (37.7mol%) compared with the very low formation of MS (2.93mol%) with Pt/TPPTS catalysts. Even at a reduction level of IV=72 a sufficient amount of C18:3 esters (2.9mol%) still remained over Pt/Al2O3 catalysts whereas with Pt/TPPTS at IV=70 the conversion of C18:3 esters was quantitative. A recycling experiment at a higher temperature of 80°C showed that the catalytic activity of water-dispersible platinum(0) nanoparticle catalysts stabilized by TPPTS remained high in a consecutive run and possess the potential to be recycled without any loss of catalytic activity. This partial hydrogenation reaction of MELO employing platinum(0) nanoparticle-TPPTS-lecithin-stabilized catalytic systems is an interesting model of a catalytic reaction for studying the selective partial hydrogenation of edible vegetable oils to foodstuffs with very low or zero amounts of both undesired products namely trans-fats and fully saturated fats employing environmentally attractive aqueous/organic two-phase systems.

Selective Partial Hydrogenation of Methyl Linoleate Using Highly Active Palladium Nanoparticles in Polyethylene Glycol

Partial hydrogenation of carbon–carbon double bonds is among one of the approaches to improve the low oxidative stability of vegetable biodiesel, which is an important drawback in biodiesel technology. In the current work, we developed an efficient two-phase catalytic system utilizing Pd(OAc)2 dissolved in polyethylene glycol (PEG) that in situ generates palladium nanoparticles in order to promote a selective partial hydrogenation reaction of methyl linoleate into mono-hydrogenated compounds while avoiding the generation of saturated compounds. High yield of methyl oleate was also obtained by hydrogenation of sunflower oil biodiesel using the same catalytic system. Through evaluating the palladium nanoparticles by TEM analysis, it is observed that 4 nm palladium nanoparticles generated in situ in PEG4000 showed high selectivity both for the partial hydrogenation of methyl linoleate and sunflower oil biodiesel.

Partial Hydrogenation of Sunflower Oil-derived FAMEs Catalyzed by the Efficient and Recyclable Palladium Nanoparticles in Polyethylene Glycol.

One approach to improve the oxidative stability of biodiesel is the partial hydrogenation of carbon-carbon double bonds. In the current work, an efficient catalytic system using Pd(OAc)2 dissolved in polyethylene glycol (PEG) which in situ generates palladium nanoparticles was developed in order to promote a selective partial hydrogenation reaction of sunflower oil FAMEs into mono-hydrogenated products avoiding the formation of saturated compounds or trans-isomers. High content of methyl oleate (85.0±1.4%) was obtained by hydrogenation of sunflower oil biodiesel with only 7.0±0.2% stearic acid. Through evaluating the palladium nanoparticles by TEM analysis, it is observed that 4 nm palladium nanoparticles generated in situ in PEG4000 are highly selective for the partial hydrogenation of sunflower oil biodiesel. And the Pd-PEG4000 catalyst can be resued for five times without obvious loss of activity or methyl oleate selectivity.

PdNP@Titanate Nanotubes as Effective Catalyst for Continuous‐Flow Partial Hydrogenation Reactions

AbstractPd nanoparticles were easily immobilized onto titanate nanotubes by a straightforward procedure. The material (0.50 wt % Pd) was used as catalyst in the continuous‐flow, liquid‐phase hydrogenation reaction of unsaturated C−C bonds and it showed excellent performance and durability under very mild conditions (room temperature, 1–2 bar H2, residence time 13–36 s). In particular, very high productivity was obtained in the synthesis of the perfumery component cis‐3‐hexen‐1‐ol (40.6 mol gPd−1 h−1) without additives or metal contamination, with clear benefits in terms of process economy and environmental impact compared with conventional catalysts. The catalyst performance is discussed in the light of comparable systems.

Supercritical fluid deposition of Ru nanoparticles onto SiO2 SBA-15 as a sustainable method to prepare selective hydrogenation catalysts

Ru/SiO2 SBA-15 materials prepared using supercritical CO2 (scCO2) are efficient and selective catalysts in partial hydrogenation reactions.