Intrinsic kinetics of catalytic hydrogenation of 2-nitro-4-acetylamino anisole to 2-amino-4-acetylamino anisole over Raney nickel catalyst

The catalytic hydrogenation of 2-nitro-4-acetylamino anisole(NMA)is a less-polluting and efficient method to produce 2-amino-4-acetamino anisole(AMA).However,the kinetics of catalytic hydrogenation of NMA to AMA remains obscure.In this work,the kinetic models including power-law model and Langmuir-Hinshelwood-Hougen-Watson(LHHW)model of NMA hydrogenation to AMA catalyzed by Raney nickel catalyst were investigated.All experiments were carried out under the elimination of mass transfer resistance within the temperature range of 70–100°C and the hydrogen pressure of 0.8–1.5 MPa.The reaction was found to follow 0.52-order kinetics with respect to the NMA concentration and 1.10-order kinetics in terms of hydrogen pressure.Based on the LHHW model,the dual-site dissociation adsorption of hydrogen was analyzed to be the rate determining step.The research of intrinsic kinetics of NMA to AMA provides the guidance for the reactor design and inspires the catalyst modification.

RuRh Bimetallic Nanoparticles Stabilized by 15-membered Macrocycles-terminated Poly(propylene imine) Dendrimer:Preparation and Catalytic Hydrogenation of Nitrile–Butadiene Rubber

A new fourth-generation poly(propylene imine) dendrimer(G4-M) containing 32 triolefinic 15-membered macrocycles on the surfaces has been synthesized. The bimetallic Ru Rh dendrimer-stabilized nanoparticles(DSNs) were first prepared within G4-M by a co-complexation route. The new G4-M dendrimer has been characterized by 1H nuclear magnetic resonance, infrared radiation, and elemental analysis.The dendrimer-stabilized bimetallic ions and reduction courses were analyzed by UV-vis spectroscopy. Highresolution transmission electron microscopy and energy dispersive spectrometer were used to characterize the bimetallic nanoparticle size, size distribution, and particle morphology. The Ru Rh bimetallic DSNs showed high catalytic activity for the hydrogenation of nitrile-butadiene rubber.

Catalytic Hydrogenation of Nitrobenzene to Aniline by Ag/γ-Fe_2O_3

The Ag/γ-Fe_2O_3 nanocomposite was synthesized by solvothermal reduction method via using ferric nitrate and silver nitrate as raw materials, and ethylene glycol as the reducing agent. The composite was characterized by X-ray powder diffraction, scanning electron microscope, transmission electron microscope, and energy dispersive X-ray. The prepared Ag/γ-Fe_2O_3 was used for the catalytic hydrogenation of nitrobenzene to aniline by hydrazine hydrate. The factors such as the silver content in the catalyst, reaction time, reaction temperature and the regeneration of catalyst were investigated. The results showed that the yield of aniline reached 100% by utilizing the 1%wt（nitrobenzene） Ag/γ-Fe_2O_3 for the catalytic hydrogenation of nitrobenzene for 3 h to obtain aniline at 78 ℃, hydrazine hydrate as the hydrogen source, while the silver content in the catalyst was 3%mol.

Liquid-Phase Catalytic Hydrogenation of Furfural in Variable Solvent Media

Water is the most abundant compound inherently existing in bio-oils. Thus understanding the role of water within bio-oils upgrading process is essential for future engineering scale-up design. In this study, furfural was chosen as bio-oils model compound, and the catalytic hydrogenation of furfural over commercial 5%, Ru/C catalyst was firstly investigated in a series of gradient variable water/ethanol mixture solvents. Water had a significant effect on the distribution of product yields. The dominant reaction pathways varied with the water contents in the water/ethanol mixture solvents. Typically, when ethanol was used as the solvent, the main products were obtained by the hydrogenation of carbonyl group or furan ring. When pure water was used as the solvent, the rearrangement reaction of furfural to cyclopentanone should be selectively promoted theoretically. However, serious polymerization and resinification were observed herein in catalytic hydrogenation system of pure water. The catalyst surface was modified by the water-insoluble polymers, and consequently, a relative low yield of cyclopentanone was obtained. A plausible multiple competitive reaction mechanism between polymerization reaction and the hydrogenation of furfural was suggested in this study. Characterizations(TG,FT-IR,SEM)were employed to analyze and explain our experiments.

Catalytic Hydrogenation of Diacetyl Monoxime to Tetramethylpyrazine with the Soluble Transition Metal Catalysts

Catalytic hydrogenation of diacetyl monoxime to tetramethylpyrazine, by the homogeneous catalysts generated in situ from some transition metal chlorides with triphenylphosphine in ethanol under H-2 pressure of 0.6 similar to 4.6 MPa at 100 similar to 150 degrees C, has been studied. The optimum H-2 partial pressure was observed at about 1.3 MPa. The maximum conversion of diacetyl monoxime and yield of tetramethylpyrazine were 97% and 90%, respectively.

STUDIES ON THE SYNTHESIS OF BAIMUXINOL BY CATALYTIC HYDROGENATION OF DEHYDROBAIMUXINOL

Baimuxinol, a 4-hydroxymethyl agarofuran isolated from Aquilaria Sinensis, was synthsizd. The stereoselectivity of catalytic hydrogenation of dehydrobaimuxino and its derivatives was studied.

Kinetics insights into size effects of carbon nanotubes'growth and their supported platinum catalysts for 4,6-dinitroresorcinol hydrogenation

Size effects are a well-documented phenomenon in heterogeneous catalysis,typically attributed to alterations in geometric and electronic properties.In this study,we investigate the influence of catalyst size in the preparation of carbon nanotube(CNT)and the hydrogenation of 4,6-dinitroresorcinol(DNR)using Fe_(2)O_(3)and Pt catalysts,respectively.Various Fe_(2)O_(3)/Al_(2)O_(3)catalysts were synthesized for CNT growth through catalytic chemical vapor deposition.Our findings reveal a significant influence of Fe_(2)O_(3)nanoparticle size on the structure and yield of CNT.Specifically,CNT produced with Fe_(2)O_(3)/Al_(2)O_(3)containing 28%(mass)Fe loading exhibits abundant surface defects,an increased area for metal-particle immobilization,and a high carbon yield.This makes it a promising candidate for DNR hydrogenation.Utilizing this catalyst support,we further investigate the size effects of Pt nanoparticles on DNR hydrogenation.Larger Pt catalysts demonstrate a preference for 4,6-diaminoresorcinol generation at(100)sites,whereas smaller Pt catalysts are more susceptible to electronic properties.The kinetics insights obtained from this study have the potential to pave the way for the development of more efficient catalysts for both CNT synthesis and DNR hydrogenation.

Hierarchical ZrO_(2)@N-doped carbon nano-networks anchored ultrafine Pd nanoparticles for highly efficient catalytic hydrogenation

Carbon supported metal catalysts have received considerable interest due to their widespread applications in heterogeneous catalysis.However,the controllable synthesis of carbon support with defined morphology and composition still represents great challenging.Herein,we reported the synthesis of a well-defined hierarchically nanosized H-ZrO_(2)/NC(nitrogen-doped carbon)network via an inheritable carbonization strategy.When immobilizing the palladium clusters into the support,the N-doped sites and oxygen vacancy of the carbon composite can effectively stabilize and activate Pd through strong metal-support interaction which was also confirmed by density functional theory(DFT)calculations.Moreover,the hierarchically nanosized network can contribute to the exposure of active sites and facilitate the mass transfer during the catalytic process.As a result,benefiting from the hierarchical structure,composition and hydrolytic nature,Pd@H-ZrO_(2)/NC exhibited excellent catalytic activity and stability towards the hydrogenation of furfural in mild reaction conditions,as well as good universality toward the hydrogenation of a series of unsaturated hydrocarbons.

Novel hollow microsphere with porous carbon shell embedded with Cu/Co bimetal nanoparticles:Facile large-scale preparation and catalytic hydrogenation performance

Non-noble bimetals have attracted extensive attention for their natural aboundance and low cost,but it remains a big challenge to design and synthesize novel supported non-noble bimetal nanocatalyst in a controllable and high-efficient manner.Herein,a novel hollow spherical supported non-noble bimetal nanocatalyst with porous carbon shell as the continuous matrix and Cu/Co bimetal nanoparticles as the dispersion phase is successfully fabricated by a convenient strategy involving spray drying and subsequent heat treatment.The morphology and microstructure depend catalyst activity of the hollow spherical supported catalyst has been studied systematically.It is found that the heating temperature plays a critical role in determining the microstructure and catalytic performance of the products.With an optimal heating temperature of 600°C,the corresponding product exhibits the highest normalized reaction rate constant(k_(n))of 25.4 s^(-1)g^(-1)for catalytic reduction of 4-notrophenol,which can be attributed to the suitable synergism of the well-defined bimetal structure,combined effect of the two metallic phases and the metal-support interaction.This work provides an additional strategy for the simultaneous formation of both the support and the active loading phase of supported non-noble bimetal nanocatalyst,and may shed some light on the high-efficiency synthesis of other supported heterostructure with various compositions and properties.

Catalytic hydrogenation of insoluble organic matter of CS_(2)/Acetone from coal over mesoporous HZSM-5 supported Ni and Ru

Four supported catalysts,nickel and ruthenium on a HZSM-5 support,were prepared by equal volume impregnation and in-situ decomposition of carbonyl nickel.The properties of catalysts were investigated by catalytic hydro-conversion of 2,2′-dinaphthyl ether as the model compound and extraction residue of Naomaohu lignite as the sample under an initial H2 pressure of 5 MPa and temperature at 150℃.According to the catalytic hydroconversion results of the model compound,Ni−Ru/HZSM5 exhibited the best catalytic performance.It not only activated H2 into H…H,but also further heterolytically split H…H into immobile H‒attached on the acidic centers of Ni−Ru/HZSM-5 and relatively mobile H+.Catalytic hydro-conversion of the extraction residue from Naomaohu lignite was further examined over the optimized catalyst,Ni−Ru/HZSM-5.Detailed molecular compositions of products from the extraction residue with and without hydrogenation were characterized by Fourier transform infrared spectroscopy and gas chromatography/mass spectrometry.The analytical results showed that the oxygencontaining functional groups in products of hydrogenated extraction residue were obviously reduced after the catalytic treatment.The relative content of oxygenates in the product with catalytic treatment was 18.57%lower than that in the product without catalytic treatment.

hcp-phased Ni nanoparticles with generic catalytic hydrogenation activities toward different functional groups

Catalytic hydrogenation is a vital industrial means to produce value-added fuels and fine chemicals,however, requiring highly efficient catalysts, especially the nonprecious ones. To date, the majority of high-performance industrial hydrogenation catalysts are made of precious metals-based materials, and any given catalyst could only be used to catalyze one or few specific reactions. Herein, we exemplify a crystal phase engineering approach to empower Ni nanoparticles(NPs) with superb intrinsic catalytic activities toward a wide spectrum of hydrogenation reactions. A facile pyrolysis approach is used to directly convert a Ni-imidazole MOF precursor into hexagonal close-packed(hcp)-phased Ni NPs on carbon support. The as-synthesized hcp-phased Ni NPs exhibit unprecedented hydrogenation catalytic activities in pure water towards nitro-, aldehyde-, ketone-, alkene-and N heterocyclic-compounds, outperforming the face-centered cubic(fcc)-Ni counterpart and the reported transition metalsbased catalysts. The density functional theory calculations unveil that the presence of hcp-Ni boosts the intrinsic catalytic hydrogenation activity by coherently enhancing the substrate adsorption strength and lowering the reaction barrier energy of the rate-determining step. We anticipate that the crystal phase engineering design approach unveiled in this work would be adoptable to other types of reactions.

Catalytic Hydrogenation of α,β-Epoxyketones to β-Hydroxyketones with Two Sulfinyl Analogues of Coenzyme NADH Models

An efficient method for the selective hydrogenation of a series of α,β-epoxyketones to β-hydroxyketones using catalytic amount of two sulfinyl analogues of NAD^＋ model compounds is reported. The lack of any diastereoselectivity for the formation of β-hydroxyketones with optically pure sulfinyl analogue of NAD^＋ model supports the radical mechanism proposed previously.

Benzene selective hydrogenation over supported Ni(nano-) particles catalysts: Catalytic and kinetics studies

This report aims to reduce the benzene in a mixture of benzene and toluene as a model reaction using catalytic hydrogenation. In this research, we developed a series of catalysts with different supports such as Ni/HMS, Ni/HZSM-5, Ni/HZSM5-HMS, Ni/Al2O3 and Ni/SiO2. Kinetic of this reaction was investigated under various hydrogen and benzene pressures. For more study, two kinetic models have also been selected and tested to describe the kinetics for this reaction. Both used models, the power law and Langmuir-Hinshelwood, provided a good fit toward the experimental data and allowed to determine the kinetic parameters. Among these catalysts, Ni/Al2O3 showed the maximum benzene conversion （99.19%） at 130℃ for benzene hydrogenation. The lowest toluene conversion was observed for Ni/SiO2. Furthermore, this catalyst presented high selectivity to benzene （75.26%） at 130℃. The catalytic performance （activity, selectivity and stability） and kinetics evaluations were shown that the Ni/SiO2 is an effective catalyst to hydrogenate benzene. It seems that the surface properties particularly pore size are effective parameter compared to other factors such as acidity and metal dispersion in this process.

Asymmetric catalytic hydrogenation of imines and enamines in natural product synthesis

Asymmetric catalytic hydrogenations of imines and enamines with chiral transition-metal complexes bearing chiral ligands are among the most green and powerful approaches for the elaboration of chiral amine structures in organic synthesis.This review focuses on recent applications of asymmetric hydrogenations of imine and enamine substrates in the total syntheses of natural products.These applications include diverse processes involving asymmetric transfer hydrogenation(ATH)and asymmetric hydrogenation(AH)to form key chiral amine motifs in natural products with good efficiency and high-level enantiocontrol.

Selective hydrogenation of glucose to sorbitol with tannic acid-based porous carbon sphere supported Ni-Ru bimetallic catalysts

Ni-Ru bimetallic porous carbon sphere(Ni-Ru@PCS) catalysts were synthesized via formaldehyde-assisted, metal-coordinated crosslinking sol-gel chemistry, in which biomass-derived tannic acid and F127 surfactant were used as carbon precursor and soft template, respectively, and Ni2+and Ru3+were used as cross-linkers. In the developed method, Ni-Ru particles became uniformly dispersed in the carbon skeleton due to strong coordination bonds between metal ions(Ni2+and Ru^(3+)) and tannic acid molecules and bimetal interactions. The as-synthesized Ni-Ru10:1@PCS catalyst with a loading Ni:Ru mole ratio of 10:1 was applied for the selective hydrogenation of glucose to sorbitol, and provided 99% glucose conversion with a sorbitol selectivity of 100% at 140℃ in 150 min reaction time and exhibited good stability and recyclability in which sorbitol yield remained at 98% after 4 cycles with little or no metal agglomeration. The catalyst was applied to glucose solutions as high as 20 wt% with 97% sorbitol yields being obtained at 140℃ in 20 h. The developed bimetallic porous carbon sphere catalysts take advantage of sustainably-derived materials in their structure and are applicable to related biomass conversion reactions.

Effect of hydrogen combustion reaction on the dehydrogenation of ethane in a fixed-bed catalytic membrane reactor

A two-dimensional non-isothermal mathematical model has been developed for the ethane dehydrogenation reaction in a fixed-bed catalytic membrane reactor. Since ethane dehydrogenation is an equilibrium reaction,removal of produced hydrogen by the membrane shifts the thermodynamic equilibrium to ethylene production.For further displacement of the dehydrogenation reaction, oxidative dehydrogenation method has been used.Since ethane dehydrogenation is an endothermic reaction, the energy produced by the oxidative dehydrogenation method is consumed by the dehydrogenation reaction. The results show that the oxidative dehydrogenation method generated a substantial improvement in the reactor performance in terms of high conversions and signi ficant energy saving. It was also established that the sweep gas velocity in the shell side of the reactor is one of the most important factors in the effectiveness of the reactor.

CATALYTIC PERFORMANCE OF MIXED-BIMETALLIC RUTHENIUM CARBONYL CLUSTERDERIVED CATALYSTS IN CO HYDROGENATION

The bimetallic catalysts prepared from SiO_2-supported Ru-Co,Ru- Fe and Ru-Mo carbonyl clusters exhibited high yields and selectivities towards oxygenates such as C_1-C_5 from CO+H_2,in contrast to the catalysts prepared from homometallic and bimetallic Ru,Ru-Ni,Ru-Rh,Ru-Mn,and Ru- Cr carbonyl clusters.The FTIR investigation revealed that the 1584 cm^(-1) species plays an important role in the formation of oxygenates in CO hydrogenation,which is possibly assigned to surface formyl species.

Carbon coated LaFe_(0.92)Pd_(0.08)O_(3) composites for catalytic transfer hydrogenation:Balance in the ability of substrates adsorption and conversion

Catalytic transfer hydrogenation(CTH)is a green and efficient pathway for selective hydrogenation of unsaturated aldehydes and ketones.However,managing the abilities of solid catalysts to adsorb substrates and to convert them into desired products is a challenging task.Herein,we report the synthesis of carbon coated LaFe_(0.92)Pd_(0.08)O_(3) composites(LFPO-8@C)for CTH of benzaldehyde(BzH)into benzyl alcohol(BzOH),using isopropanol(IPA)as hydrogen source.The coating with carbon improves the ability to adsorb/transfer reactants from solution to active sites,and the doping of Pd2+at Fe3+site strengthens the ability of LaFeO_(3) to convert BzH into BzOH.A balanced point between them(i.e.,abilities to adsorb BzH and to convert BzH into BzOH)is obtained at LFPO-8@C,which exhibits a BzOH formation rate of 3.88 mmol·gcat^(-1)·h^(-1) at 180℃ for 3 h,which is 1.50 and 2.72 times faster than those of LFPO-8 and LaFeO_(3)@C.A reaction mechanism is proposed,in which the acidic sites(e.g.,Fe^(4+),oxygen vacancy)are used for the activation of C=O bond of BzH and O-H bond of IPA,and the basic sites(e.g.,lattice oxygen)for the activation ofα-H(O-H)bond of IPA.

The Effect of Titania Structure on Ni/TiO_2 Catalysts for p-Nitrophenol Hydrogenation

The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over Ni/TiO2 catalysts prepared by a liquid-phase chemical reduction method. The catalysts were characterized by inductively coupled plasma (ICP), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS) and temperature-programmed reduction (TPR). Results show that the titania structure has favorable influence on physio-chemical and catalytic properties of Ni/TiO2 catalysts. Compared to commercial Raney nickel, the catalytic activity of Ni/TiO2 catalyst is much superior, irrespective of the titania structure. The catalytic activity of anatase titania supported nickel catalyst Ni/TiO2(A) is higher than that of rutile titania supported nickel catalyst Ni/TiO2(R), possibly because the reduction of nickel oxide to metallic nickel for Ni/TiO2(A) is easier than that for Ni/TiO2(R) at similar reaction conditions.

Effect of Alumina Particle Size on Ni/Al2O3 Catalysts for p-Nitrophenol Hydrogenation

The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over Ni/Al2O3 catalyst on alumina support with different particle size. It is found that support particle size has significant influences on physiochemical properties and catalytic activity of the resulting Ni/Al2O3 catalyst, but little influence on the selec-tivity. At a comparable amount of Ni loading, the catalytic activity of Ni/Al2O3 prepared with alumina support of smaller particle size is lower. The reduction behavior of the catalyst is a key factor in determining the catalytic activity of Ni/Al2O3 catalyst. The supported nickel catalyst 10.3Ni/Al2O3-3 improves the life span of the membrane by reducing fouling on the membrane surface compared to nano-sized nickel.