Kinetics Of Liquid-phase Hydrogenation Research Articles

HYDROGEN PRESSURE, SOLVENT AND CATALYST NATURE INFLUENCE ON THE 2-CHLORO-4-NITROANILINE HYDROGENATION REGULARITIES

The 2-chloro-4-nitroaniline liquid-phase hydrogenation kinetics on supported palladium and platinum catalysts differing in the nature of the carrier and the active metal content was studied for the first time. The experiment was carried out at elevated hydrogen pressures in the range of 9 - 12 atm and 303 K in solvents 2-propanol-water and ethyl acetate in the reactor such as Vishnevsky autoclave. The main kinetic parameters of the reaction have been determined, and the influence of various parameters on the regularities of the process has been established. It is shown that an increase in the active metal content in the catalyst leads to an increase in the rate of the hydrogenation reaction of 2-chloro-4-nitroaniline. When using platinum supported catalysts, the rate of hydrogenation of 2-chloro-4-nitroaniline is significantly higher than when using supported palladium catalysts. The replacement of the liquid phase of the catalyst system with 2-propanol by ethyl acetate adversely affects the reaction rate. The influence of the catalytic system nature and composition on the target product dehalogenation degree was determined. It was found that when carrying out the reaction at elevated hydrogen pressures, it is preferable to use low-percentage platinum catalysts, rather than palladium catalysts, since the former provide less dehalogenation of the target product.
 For citation:
 Klimushin D.M., Krasnov A.I., Filippov D.V., Sharonov N.Yu. Hydrogen pressure, solvent and catalyst nature influence on 2-chloro-4-nitroaniline hydrogenation regularities. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 9-10. P. 30-35

KINETICS OF HYDROGENATION OF NITROBENZENE, 4-NITROTOLUENE, 4-NITROANILINE AND 2-CHLORO-4-NITROANILINE ON SUPPORTED PALLADIUM CATALYST

A study of the kinetics of liquid phase hydrogenation of nitrobenzene, 4-nitrotoluene, 4-nitroaniline and 2-chloro-4-nitroaniline on supported palladium catalyst in aqueous solutions of 2-propanol of different composition was carried out. The influence of the substituent on the value of the total amount of hydrogen absorbed during the reaction and the kinetics of the hydrogenation of substituted nitrobenzenes was discussed. It was found out that the reaction selectivity to 2-chloro-1,4-phenylenediamine decreases due to by-reaction dehalogenation. The degree of dehalogenation depends on the composition of solvent and may be approximately estimated by the values of the absorbed hydrogen volume during the reaction. Also, the presence of the donor-acceptor substituents is capable of exerting influence on the reaction rate of hydrogenation of the nitro compound.

The kinetics of liquid-phase hydrogenation of sodium maleate by hydrogen adsorbed on the surface of Raney nickel

The kinetics of liquid-phase hydrogenation of sodium maleate by hydrogen adsorbed on the surface of Raney nickel in aqueous solutions was studied by the adsorption-calorimetric method. The kinetic reaction parameters in the surface layer were determined over a broad range of surface coverages. It was proved that a kinetic description in terms of classic kinetic approaches was formal and did not reveal the essence of the process. A description of kinetic reactions in terms of the Elovich equation for uniformly inho-mogeneous surfaces was better grounded physically.

Kinetics of Liquid‐Phase Hydrogenation of Iso‐valeraldehyde to Iso‐amyl Alcohol Over A Ru/Al2O3 Catalyst

AbstractThe liquid‐phase catalytic hydrogenation of iso‐valeraldehyde to iso‐amyl alcohol was studied in a slurry reactor. The kinetics of liquid‐phase hydrogenation of iso‐valeraldehyde over a 5% Ru/Al2O3 catalyst was studied in the range of temperature 373‐393 K and H2 pressure 0.68‐2.72 MPa using 2‐propanol as the solvent. The selectivity to iso‐amyl alcohol was 100%. The kinetic data were analyzed using a simple power law model. A single site Langmuir‐Hinshelwood type model suggesting dissociative adsorption of hydrogen and surface reaction as the rate‐controlling step provided the best fit of the experimental data. The catalyst could be reused thrice without any loss in activity.

Kinetics of Maleic Acid Hydrogenation over Skeleton Nickel in Aqueous Solutions

The kinetics of liquid-phase hydrogenation of maleic acid to succinic acid was studied over skeleton nickel catalyst in aqueous solution at different values of pH. The dependence of the substrate concentration and the amount of hydrogen absorbed on time were used to determine the reaction orders and rate constants. The effect of external and internal diffusion was evaluated and taken into account. Different reasons for the effect of pH on kinetic parameters are discussed for the reaction occurring in aqueous solutions. The values of the reaction orders found in the pH interval under investigation differed from one and changed in the range of 0.7-0.85 and 0.50-0.85. Activation energies of maleic acid, the hydrogenation reaction in aqueous solution of sodium hydroxide with pH 7.8 and 13.9 equal to 39±2 and 62±5 kJ mol , respectively. Thus maleic acid 1

Kinetics of liquid phase hydrogenation of cottonseed oil with nickel catalysts

AbstractThe hydrogenation of cottonseed oil has been carried out in a batch reactor using both unmodified and chromia modified nickel catalysts. The process variables include chromium to nickel atomic ratio (0.00–0.35), catalyst particle size (200–400 micron), temperature (120–140°C) and pressure (5–10 bar). Chromia was found to suppress the stearate formation completely, although it retarded the overall hydrogenation activity of nickel. Its optimum content in the catalyst was found to be 0.17 Cr/Ni atomic ratio; the data corresponded to 5 hr reaction time. The kinetics of the process was tested and found to follow a first order reaction with respect to linoleate and half order with respect to hydrogen. The activation energy was found to be 11.8 kcal/mole.

Effect of internal diffusion on kinetics of liquid phase hydrogenation and disproportionation of the cyclohexene on palladium catalysts

Kinetics of the side reactions represented by the system involving hydrogenation and disproportionation of cyclohexene on a commercial catalyst CHEROX 41-00 (3%Pd/C) and on a supported palladium catalyst prepared by impregnation of aluminia with aqueous palladium dichloride (2.15% Pd/γ-Al2O3) have been investigated. As follows from the effectiveness factors of internal diffusion for individual reactions, in the region of internal diffusion, cyclohexene hydrogenation is preferred compared to disproportionation. This finding can be related to the fact that while the rate of disproportionation is controlled by cyclohexene diffusion, the rate of hydrogenation is controlled by diffusion of hydrogen.

Hydrogenation activity of homogeneous and heterogenized rhodium(i) complexes containing (ω-triethoxy-silylalkyl)-diphenylphosphines

Abstract Kinetics of liquid phase hydrogenation of alkenes catalysed by homogeneous rhodium(I) complexes prepared in situ from μ, μ′-dichloro-bis-[di(alkene)rhodium] and phosphines of the type RPPh 2 (R = −(CH 2 ) n (OEt) 3 n = 1 − 6 and R = −CH 2 SiMe 3− m (OEt) m ; m − 3) and by their heterogenized analogues anchored to silica have been studied at 1.1 atm hydrogen pressure and 37 − 67 °C. The hydrogenations catalysed by catalysts of both types were found to be first order in the alkenes. The reaction rates are discussed in relation to the deactivation of the rhodium catalysts due to the dimerisation of catalytically active species. It is proposed that the dimerisation takes place also on the surface of the support and depends on the length of the spacer group separating the diphenylphosphino group from the surface.

The activity of homogeneous and heterogenized Rh(I) complexes in hydrogenation of alkenes

Kinetics of liquid phase hydrogenation of alkenes catalysed by homogeneous Rh(I) complexes prepared in situ from di-μ,μ'-chloro-bis/di(cyclooctene)rhodium/ and 3-(triethoxysilyl)propyldiphenylphosphine and by heterogenised analogues anchored to silica have been studied. The reaction was found to be first order in hydrogen, alkene and catalyst. Compared to the soluble complexes, the supported catalyst turned out to be substantially more stable. At 0.3-0.6%Rh concentrations on the support, the activity of the catalyst was not affected by pore size within 4-10 nm region. The supported catalysts prepared by functionalization of the support followed by formation of the Rh complex were more active then their homogeneous analogues.

Kinetics of Liquid Phase Hydrogenation. IV. Hydrogenation of Nitrocompounds Over Raney Nickel and Nickel Powder Catalysts

<b>Kinetics of Liquid Phase Hydrogenation. IV. Hydrogenation of Nitrocompounds Over Raney Nickel and Nickel Powder Catalysts</b>

Kinetics of Liquid Phase Hydrogenation. II. Hydrogenation of Aromatic and Aliphatic Nitrocompounds Over A Colloidal Platinum Catalyst

Kinetics of Liquid Phase Hydrogenation. II. Hydrogenation of Aromatic and Aliphatic Nitrocompounds Over A Colloidal Platinum Catalyst

Kinetics of Liquid Phase Hydrogenation. III. The Nature of Platinum Oxide Catalysts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics of Liquid Phase Hydrogenation. III. The Nature of Platinum Oxide CatalystsHsien Cheng Yao and P. H. EmmettCite this: J. Am. Chem. Soc. 1961, 83, 4, 799–801Publication Date (Print):February 1, 1961Publication History Published online1 May 2002Published inissue 1 February 1961https://doi.org/10.1021/ja01465a012RIGHTS & PERMISSIONSArticle Views149Altmetric-Citations11LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (353 KB) Get e-Alerts Get e-Alerts