Hydrogenation Of 1-butyne Research Articles

An egg-shell bifunctional CeO2-modified NiPd/Al2O3 catalyst for petrochemical processes involving selective hydrogenation and hydroisomerization

The catalytic performance during the 1-butyne hydrogenation using two reduced Al2O3-supported Pd-based catalysts was carried out in a total recirculation system with an external fixed-bed reactor. The lab-prepared egg-shell NiPd/CeO2-Al2O3 catalyst (NiPdCe) with Pd loading = 0.5 wt%, Ni/Pd atomic ratio = 1 and CeO2 loading = 3 wt% was synthesized and characterized, and it was compared with an egg-shell Al2O3-supported Pd based commercial catalyst (PdCC). The reduced catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. The textural characteristics and ammonia temperature-programmed desorption profiles of the fresh (unreduced) catalysts were also obtained. Both catalysts show high 1-butyne conversion and selectivity to 1-butene, but the catalysts also present important differences between hydroisomerizing and hydrogenating capabilities. NiPdCe catalyst shows higher capability for hydroisomerization reactions, while the PdCC catalyst exhibits higher hydrogenating capability. The observed catalytic performances can be interesting for some industrial processes and can provide a guideline for the development of a Pd-based catalyst with specific catalytic properties.

Application of a catalytic membrane reactor to the selective hydrogenation of 1-Butyne

A catalytic membrane reactor (CMR) was applied in order to enhance the selectivity in the hydrogenation of 1-butyne in the presence of 1-butene. The performance of the CMR was studied in batch-wise operation for the hydrocarbon liquid mixture, while hydrogen was continuously fed to keep a constant partial pressure. The reaction was carried out at 44 °C and partial pressures of hydrogen in the range of 1 to 5 bar. The CMR was prepared by impregnating a commercial alumina membrane disk with Pd. Experimental results were compared with those obtained in a conventional fixed bed reactor (FBR), using a commercial catalyst of egg-shell type in its original size, and in a microreactor (MR) with the same commercial catalyst milled to a size of around 40 μm. The CMR presents high activity and selectivity, comparable to the values of the milled commercial catalyst, but significantly higher than for the commercial catalyst in its original size. Kinetic parameters for the hydrogenation of 1-butyne were obtained from the regression of the experimental data. Also, a simulation of a continuous operation of both, CMR and FBR with the commercial catalyst, was carried out to show the advantage in selectivity of the CMR.

Development of a multi-layer microreactor: Application to the selective hydrogenation of 1-butyne

A multi-layer microreactor (MR) was especially developed to assess the effects of the intensification of liquid-phase selective hydrogenation of 1-butyne (BY). The behavior of the system is described and the results of the regression of experimental data are reported. Various MR configurations, differentiated by the number of catalyst layers were constructed. A commercial Pd/Al2O3 catalyst, crushed and sieved to 37–44μm particle size, has been tested. The reaction was carried out in liquid phase, at three levels of temperature (35, 44 and 60°C), and covering a range of hydrogen partial pressure of 1.2–5bar. The kinetic expression used to analyze the experimental data was based on an elementary step mechanism. Fitting of the kinetic parameters allowed to reproduce the experimental results within an average deviation of 3.7%. The results presented in this study are compared to experimental data obtained previously on the same commercial catalyst, but using the original 2.3mm spherical pellets packed in a conventional fixed bed reactor (FBR). It is concluded from such a comparison that the measurements carried out in the MR are free from diffusion limitations and that the evaluation of such effects in the FBR was satisfactorily performed.

Kinetic Evaluation of the Set of Reactions in the Selective Hydrogenation of 1-Butyne and 1,3-Butadiene in Presence of n-Butenes

The selective hydrogenation in the liquid phase of 1-butyne and 1,3-butadiene in the presence of n-butenes over a commercial Pd/Al2O3 egg-shell catalyst has been studied. Although hydrogenation of the n-butenes and their isomerization are normally undesirable, kinetics of these reactions should also be evaluated in order to carry out the process at efficient operating conditions. Here, the effect of temperature, in the range 25–65 °C, on the specific rate coefficients of 1,3-butadiene hydrogenation reactions and 1-butene, cis-2-butene, and trans-2-butene hydrogenation and isomerization reactions was evaluated from measurements in a batch reactor system. Further experiments were conducted for the evaluation of selectivity between 1-butyne and 1,3-butadiene hydrogenations at 44 °C. The present results and previous kinetic characterization allow evaluating the most relevant parameters of a set of kinetic expressions for the 10 overall reactions that govern the system transformation.

Selective Hydrogenation of 1,3‐Butadiene and 1‐Butyne over a Rh/Chitosan Catalyst Investigated by using Parahydrogen‐Induced Polarization

AbstractHydrogenation of 1,3‐butadiene and 1‐butyne over the Rh/chitosan catalyst in gaseous and liquid phases was investigated by using the NMR and parahydrogen‐induced polarization technique. The Rh/chitosan system was a very selective catalyst for the partial hydrogenation of 1,3‐butadiene and 1‐butyne to 1‐ and 2‐butenes. The catalyst demonstrated high activity in the hydrogenation of 1‐butyne after its activation in the hydrogenation of 1,3‐butadiene. Therefore, the Rh/chitosan catalyst was used for the catalytic removal of 1,3‐butadiene and 1‐butyne from gaseous butene streams. Moreover, the syn‐ and anti‐addition of the hydrogen molecule to substrates proceeded in a pairwise manner in the gas phase heterogeneous hydrogenation as was demonstrated by parahydrogen‐induced polarization. However, in the liquid phase hydrogenation of 1‐butyne, both hydrogen atoms from the same hydrogen molecule were added to 1‐butyne only through the syn‐addition route.

Kinetic study of the liquid-phase selective hydrogenation of 1-butyne in presence of 1-butene over a commercial palladium-based catalyst

A kinetic investigation of the liquid-phase selective hydrogenation of 1-butyne in presence of 1-butene was performed over a commercial palladium-based/alumina catalyst of the eggshell type. This investigation is aimed at validating a kinetic expression to describe 1-butyne hydrogenation under experimental conditions around the typical operating conditions of industrial C 4 cuts hydrorefining processes. Seven levels of temperature between 27 °C and 62 °C were explored. 1-Butyne and n-butene initial mole fractions amounted to ca. 8% and 9% and hydrogen partial pressure was set between 0.85 atm and 7.82 atm. Experimental data and data analysis were extended to 1-butyne total conversion. Palladium proved to be quite selective towards 1-butyne hydrogenation. However, the intrinsic palladium selectivity is impaired by the presence in our experiments of severe intracatalyst diffusion limitations. This result turns the attention to the crucial influence of hydrogen partial pressure level on selectivity because unnecessary hydrogen excesses severely lessen selectivity when 1-butyne becomes the limiting reactant inside the catalyst. A kinetic expression of the Langmuir–Hinshelwood–Hougen–Watson type was proposed to describe the hydrogenation of 1-butyne. 1-Butene hydrogenation rate was described by a zero-order and first-order kinetic expression with respect to 1-butene and hydrogen, respectively. The kinetic model predicts experimental data with an average deviation of 17.1%. The relative inference intervals of the kinetic parameter estimates were less than ±14.8%.

Kinetic study of the liquid-phase hydrogenation of 1-butyne over a commercial palladium/alumina catalyst

Abstract Hydrorefining of C4 cuts of unsaturated hydrocarbons involves the selective removal of 1-butyne by catalytic hydrogenation. Due to its technological relevance, we investigated the hydrogenation of 1-butyne over a commercial palladium-based catalyst of the eggshell type. The experimental conditions were selected to reproduce those of industrial hydrorefining reactors: liquid-phase reaction, seven levels of temperature between 27 and 62 °C, initial concentrations of 1-butyne up to 0.6 mol/l and hydrogen partial pressure ranging from 0.8 to 8 atm. Under these conditions, the overall effectiveness factor of 1-butyne hydrogenation was less than 0.15. Provided that hydrogen was the limiting reactant inside the active shell, 1-butene was the only product yielded by 1-butyne hydrogenation. The regression analysis of experimental data corresponding to the hydrogenation of 1-butyne to 1-butene was restricted to experimental compositions in which 1-butyne concentration was higher than 0.07 mol/l. An intrinsic kinetic expression with reaction orders 1 and −1 for hydrogen and 1-butyne, respectively, predicts experimental data with an average deviation of 2.1%. Estimates of the activation energy and kinetic coefficient at 44 °C are (1.55 ± 0.06) 104 cal/mol and (4.6 ± 0.1) mol/(kg s).

Selective hydrogenation of C 4-alkynes over a copper on silica catalyst

The selective gas phase hydrogenation of 1-butyne, 1-butene-3-yne, 1,3-butadiene and of an industrial C 4-feed stream has been examined in a flow system employing a Cu/SiO 2 catalyst. The variations in product distributions with temperature, hydrogen partial pressure and C 4-reactant partial pressure have been determined together with the kinetics and activation energies. No butane formation was observed for all experiments, proving the Cu/SiO 2 catalyst to be highly selective for the formation of alkenes. Butene isomerisation was found to be negligible for all reactions. Catalyst deactivation, as a result of the build-up of oligomeric material on the catalyst surface was particularly pronounced for the C 4-alkynes but could be minimised by applying elevated temperatures and increased hydrogen partial pressures. Orders of reaction with respect to hydrogen (1.1–1.5), 2-butene (zero) and the C 4-reactants (zero) indicate that the strengths of adsorption decrease in the sequence: alkyne > dialkene > alkene ⩾ hydrogen. Apparent activation energies for the formation of 1-butene were measured as 69 kJ/mol (1-butyne), 62 kJ/mol (1-butene-3-yne) and 63 kJ/mol (1,3-butadiene). In competitive hydrogenation reactions the alkynes were selectively hydrogenated while 1,3-butadiene was found to be inert. Thus the catalyst can be used for the selective removal of alkynes from industrial C 4-streams.

Additive effects in the selective hydrogenation of unsaturated hydrocarbons on platinum and rhodium catalysts: I: Influence of nitrogen-containing compounds

Hydrogenation of unsaturated hydrocarbons such as 1-butene, 1,3-butadiene and 1-butyne was studied in the liquid phase on platinum and rhodium catalysts after addition of an electron-donating compound, piperidine. Piperidine decreases the hydrogenation rate of 1-butene and 1,3-butadiene but increases that of 1-butyne on highly dispersed platinum catalysts. The selectivities for the formation of olefins from 1,3-butadiene and 1-butyne are increased. Such positive influences either on selectivity or on both selectivity and activity are interpreted by an electronic effect modifying the adsorption properties of the catalytic sites. This interpretation is substantiated by infrared studies of the coadsorption of carbon monoxide and piperidine on platinum catalysts of various dispersions. For rhodium catalysts, piperidine has a negligible effect on 1-butyne hydrogenation rate but increases the hydrogenation rate of 1,3-butadiene for the highly dispersed catalysts. In contrast to platinum, the effect on selectivities for olefin formation is negligible.

Hydrogenation of unsaturated hydrocarbons in liquid phase on palladium, platinum and rhodium catalysts: III. Quantitative Selectivity Ranking of Platinum, Palladium and Rhodium in the Hydrogenation of 1-Butene, 1,3-Butadiene and 1-Butyne Using a Single Reaction Scheme

The selectivity of platinum and rhodium in the hydrogenation of 1-butene, 1,3-butadiene and 1-butyne have been determined and compared with that of palladium. The experimental results are rationalized using a single reaction scheme accounting for primary parallel formation of 1-butene, 2-butenes and butane and consecutive formation of 2-butenes and butane from the 1-butene initially produced. Platinum and rhodium behave very similarly and are not very different from palladium for hydrogenations of 1-butyne and 1,3-butadiene except for the initial formation of butane: platinum and rhodium produce a lot of “initial” butane ( S BA pO) unlike palladium which is characterized by a selectivity index S BA p of zero. This particular behaviour of palladium is also apparent in the trans/cis ratio for 2-butenes produced from butadiene hydrogenation, this ratio being 3.5 for platinum and rhodium and 12 for palladium. Results from of our laboratory and from the literature on Group VIII metals, either as heterogeneous or homogeneous catalysts, show that the initial formation of butane increases while the trans/cis ratio decreases. It seems that this correlation is not by chance and we propose that butane is formed via a semi-hydrogenated species, originating from a syn-diadsorbed 1,3-butadiene, from which cis-2-butenes are formed.

Liquid phase hydrogenation of unsaturated hydrocarbons on palladium, platinum and rhodium catalysts. Part I: kinetic study of 1-butene, 1,3-butadiene and 1-butyne hydrogenation on platinum.

A quantitative kinetic study of the liquid phase hydrogenation of 1-butene, 1,3-butadiene and 1-butyne hydrogenation on platinum supported catalysts has been performed. The hydrogenation of 1-butene and 1,3-butadiene is compatible with a simple Langmuir-Hinshelwood kinetic equation, whereas the hydrogenation of 1-butyne is not. The comparative apparent sensitivities to metal dispersion distinguishes similarly the 1-butyne, which is sensitive, from the others, which are not. All the experimental data are well interpreted by a “multicomplexation” mechanism where the surface atoms of low coordination number are reversibly deactivated by the adsorption of two molecules of 1-butyne.

Liquid phase hydrogenation of unsaturated hydrocarbons on palladium, platinum and rhodium catalysts. Part II: kinetic study of 1-butene, 1,3-butadiene and 1-butyne hydrogenation on rhodium; comparison with platinum and palladium

A quantitative kinetic study of the liquid phase hydrogenation of 1-butene, 1,3-butadiene and 1-butyne on rhodium supported catalysts has been performed. Unlike 1-butene hydrogenation, which can be represented by a simple Langmuir-Hinshelwood kinetic equation, the 1,3-butadiene and 1-butyne hydrogenationsfollow a more complex kinetic rate law. Comparable apparent sensitivities to metal dispersion also distinguish the 1,3-butadiene and 1-butyne, which are sensitive, from the 1-butene which is not. As previously shown with 1-butyne on platinum and palladium, the results obtained on rhodium can also be interpretated by a “multicomplexation” mechanism where the active sites, on metallic surfaces constituted by atoms of low coordination number, are reversibly deactivated by the adsorption of two molecules of 1-butyne. The feature for rhodium is that this “multicomplexation” effect is observed not only for 1-butyne but also for 1,3-butadiene. In conclusion, a single kinetic model can account for four systems: Pt-butyne Pd-butyne, Rh-butyne and Rh-butadiene. This kinetic interpretation allows us to determine a “multicomplexation” coefficient K' which depends on the metal dispersion and an intrinsic rate constant k which is independent of the metal dispersion. Finally a quantitative activity classification is obtained for the three metals and the three hydrocarbons studied.

Hydrogenation of highly unsaturated hydrocarbons over highly dispersed palladium catalyst: Part I: behaviour of small metal particles

Hydrogenation of 1-butyne over palladium catalysts with dispersions between 9 and 100% reveals that the reaction is sensitive to metallic dispersion. A similar sensitivity is also exhibited by 1, 3-butadiene and isoprene, whereas 1-butene is insensitive to dispersion. This behaviour of the highly unsaturated hydrocarbons is explained by the formation of a strong complex of these hydrocarbons with very small particles at high dispersion.