N-decane Dehydrogenation Research Articles

The effect of tin on the formation and properties of Pt/MgAl(Sn)Ox catalysts for dehydrogenation of alkanes

The MgAl(Sn) layered double hydroxides (LDH) with the atomic ratios Mg/(Al + Sn) = 3 and Sn/(Sn + Al) = 0, 0.002, 0.005, 0.01, 0.05, 0.1, 0.3, 0.5, 0.7, 1.0 were synthesized and the ratio Sn/(Sn + Al) ≤ 0.1 was shown to provide the formation of systems with uniform phase composition. Mixed oxides derived from LDH retain the high specific surface area of 150-200 m2/g and the basic properties when some aluminium atoms are replaced with tin. It was found that the Sn-containing mixed oxides are able to restore the layered structure during rehydration and intercalate the anion precursors of platinum into the interlayer space of the formed LDH. The emerging platinum sites initiate the reduction of tin at temperatures below 723 K. TEM, EXAFS and XPS studies demonstrated that tin introduction in the support increases the dispersion of supported platinum. An extreme dependence of the activity of Pt/MgAl(Sn)Ox catalysts in propane and n-decane dehydrogenation on the tin content in the support was revealed. The active catalysts are characterized by the phase and elemental uniformity of the support, highly disperse state of Pt(0), and the absence of a noticeable amount of reduced tin and bimetallic particles.

Effect of the nature of the active-component precursor on the properties of Pt/MgAlO x catalysts in propane and n-decane dehydrogenation

The Pt/MgAlO x catalysts, in which a mixed aluminum–magnesium oxide obtained by the heat treatment of corresponding layered double hydroxides was used as a support, were studied. The effects of the nature of active-component precursors ([PtCl6]2–, [PtCl4]2–, and [Pt3(CO)6] 6 2- ), and the Mg/Al ratio in the support on the anchoring of complexes, the disperse state of platinum, and the properties of the obtained catalysts in the reactions of propane and n-decane dehydrogenation were found.

Study of Pt/MgAlO x catalysts in n-decane dehydrogenation

The properties of Pt/MgAlOx catalysts based on aluminum–magnesium layered hydroxides have been investigated in n-decane dehydrogenation. The n-decene formation selectivity depends on the Mg/Al ratio in the support, on the platinum complex binding conditions, and on the platinum content of the catalyst. Increasing the proportion of magnesium decreases the number of acid cites in the support and changes the properties of supported platinum. As a result, the n-decene formation selectivity under the appropriate conditions reaches 90% without a modifier added.

N-decane dehydrogenation on bimetallic PtSn and PtGe catalysts prepared by dip-coating

The catalytic performance of Pt, PtSn and PtGe supported on γ-Al2O3 (γ-A) deposited by dipcoating of spheres of α-Al2O3 (α-A) was studied in the n-decane dehydrogenation. The effect of Sn and Ge addition to Pt on the activity and selectivity was analyzed. The catalytic characterization was carried out using cyclohexane dehydrogenation (CHD), cyclopentane hydrogenolysis (CPH), temperature-programmed reduction (TPR), hydrogen chemisorption, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and scanning electronic microscopy (SEM). Pt(0.5)Sn/γ-A/α-A catalyst had the best catalytic performance and showed a low electronic interaction between the metals, with a surface segregation of Sn and the presence of oxidized Sn stabilized on the support. PtGe catalysts presented strong interactions with probable alloy formation. The catalytic performance of these catalysts is comparable to that reported in the patents.

N-Decane dehydrogenation on Pt, PtSn and PtGe supported on spinels prepared by different methods of synthesis

The catalytic performance of Pt, PtSn and PtGe supported on ZnAl2O4 obtained by mechanochemical synthesis (MS) or coprecipitation (COPR) is studied in the production of 1-decene from the n-decane dehydrogenation. The effect of preparation methods and Sn and Ge addition to Pt on the activity and selectivity was analyzed. The catalytic characterization was carried out by using XRD, Specific surface area, 2-propanol dehydration reaction, equilibrium pH, cyclohexane dehydrogenation (CHD), cyclopentane hydrogenolysis (CPH), TPR, H2 chemisorption, XPS, TPO, and TEM. Characterization studies indicate that the addition of Sn to the Pt metal phase modifies not only the catalytic properties, but deactivation and stability as well. PtSn catalysts on both spinels were more active, with lower activity fall than PtGe ones and the higher the Sn loading, the more noticeable this effect. Besides, PtSn catalysts supported on ZnAl2O4 MS showed a more stabilizing effect.

Knowledge Based Catalyst Design by High Throughput Screening of Model Reactions and Statistical Modelling

Material design and synthesis are key steps in the development of catalysts. They are usually based on an empiric and/or theoretical approach. The recently developed high-throughput experimentation can accelerate optimisation of new catalytic formulations by systematic screening in a predefined study domain. This work aims at developing a QSAR (Quantitative Structure Activity Relationship) method based on kinetic and mechanistic descriptors for metal and acid catalysis. Physico-chemicalfeatures of approximately sixty bimetallic catalysts have been measured according to their performance in two model reactions: xylene hydrogenation for catalysis on metallic sites and isomerisation of 3,3-dimethyl-l-butene for catalysis on acid sites. These descriptors were finally used to model the performances of around twenty catalysts for a more complex reaction: n-decane dehydrogenation.

Lithium promoted Pt−Sn/Al2O3 catalysts for dehydrogenation ofn-decane: Influence of lithium metal precursors

Four lithium metal precursors (LiNO3, CH3COOLi, LiOH, LiCl) have been used as promoters in Pt−Sn/Al2O3 catalysts to improve activity, selectivity and stability in a modeln-decane dehydrogenation reaction. Acidity, TPR and TPCO measurements have shown that the precursors affect the acid site distribution in the support, modify the reducibility and dispersity of Pt−Sn active species, coke lay-over patterns, stability and also selectivity for formation of monoolefins in the dehydrogenation ofn-decane.

Effect of modification of alumina-platinum catalysts on the composition of arenes formed during dehydrogenation of higher n-paraffins

1. 1. An investigation has been made of the composition of aromatic hydrocarbons and n-olefins formed during dehydrogenation of n-decane on alumina-platinum catalysts modified with elements of the manganese subgroup. The main products of the reaction of aromatization in the studied conditions are in n-butylbenzene and also o-, m-, and p-diethylbenzenes and o- and p-propyl-toluenes. n-Decenes are in a near-equilibrium ratio with all possible isomers. 2. 2. The nature of the modifying additive introduced has a considerable effect on the ratio of the different arene isomers: unlike Tc or Re, the addition of Mn to an alumina-platinum catalyst practically completely suppresses the formation of m- and p-isomers of dialkylbenzenes. 3. 3. It has been established that preliminary skeletal isomerization of aliphatic hydrocarbons plays an important part in the formation of dialkylbenzenes with substituents in the m- and p-position.

Composition of olefins formed in the dehydrogenation of n-decane over aluminum-platinum catalysts

1. The amounts of α-, cis-, and trans-decenes formed by dehydrogenation of n-decane over an aluminum-platinum catalyst corresponded on average to the proportions 1∶8∶11, and they were little affected by changes in catalyst composition and reaction conditions. 2. Decenes with nonterminal double bonds were formed preferentially (∼95 rel.%). 3. The proportions of the different forms of decenes were close to the calculated values.

Dehydrogenation of n-decane on deposited techetium catalysts

1. We were the first to study the catalytic properties of technetium deposited on Al2O3 in the dehydrogenation of n-decane and it was shown that alumina-technetium catalysts have a relatively high activity and selectivity in the formation of monoolefins.

Effect of the conditions of n-decane dehydrogenation on deactivation of the alumina-platinum catalyst

1. Deactivation of the alumina-platinum catalyst in the n-decane dehydrogenation increases with an increase in temperature (430–500°C), and decreases with an increase in either the presence of hydrogen (1·105−2.3·105 Pa) or the molar dilution of the hydrocarbon with hydrogen (4–16). 2. Under all conditions, the degree of deactivation of the catalyst, the accumulation of carbon on the catalyst surface, and combined yield of olefins and diolefins vary in parallel. 3. The degree of deactivation of the catalyst in n-decane dehydrogenation depends on both the amount of coke formed on the catalyst surface, decreasing as the latter increases. 4. Any alteration of parameters (temperature, space velocity, partial pressure of hydrogen, hydrogen dilution) which increases the yield of monoolefins and diolefins in the n-decane dehydrogenation reduces the stability of operation of the catalyst. By varying two of these parameters simultaneously it is possible to increase the yield of unsaturated hydrocarbons and to decrease the degree of deactivation of the catalyst.

Study of alumino-platinum-lithium catalysts during dehydrogenation of n-decane using the pulse method

Considerable practical significance is attached at the present time to catalytic dehydrogenation of C/sub 10/ and higher n-paraffins into mono-olefins, which form a raw material for obtaining surface-active substances (SAS) subjet to bio-decomposition. Alumino-platinum (AP) catalysts with alkali additives, mainly lithium are the most popular, according to data in patent literature. The effect of the latter on the ratio of products formed during this process has been insufficiently investigated. A study is made in this paper of dehydrogenation of n-decane in the presence of AP catalysts containing a varying amount of lithium, in order to establish the relation between the lithium additive and the variation of physico-chemical and catalytic properties of these catalysts and establish the causes of increased selectivity of catalysts in the formation of monoolefins.

Effect of properties of aluminum oxide on selectivity of Pt/Al2O3 in dehydrogenation of n-alkanes

The selectivity of Al-Pt catalysts (0.25% Pt) in the dehydrogenation of n-decane and n-hexane to n-alkenes depends on the properties of the aluminum oxide and increases in the order: Pt/η-Al2O3 Pt/θ-Al2O3.

Oxidative dehydrogenation of n-decane

Oxidative dehydrogenation of n-decane

N-Decane dehydrogenation by a cell-free extract ofCandida rugosa

n-Decane dehydrogenation by a cell-free extract ofCandida rugosa