Nickel-kieselguhr Catalyst Research Articles

Commercial nickel-kieselguhr isopropanol dehydrogenation catalysts: Morphology and catalytic and electronic properties

Isopropanol conversion over commercial nickel-kieselguhr catalyst is studied. It is found that using this catalyst allows the single-step production of acetone (in contrast to familiar two-step technologies) with a catalyst not been previously used in this process in a range of moderate temperatures with a feedstock conversion of 97% and a target product yield of 82.4%. Changes that occur in the phase composition, surface structure, and electronic properties of the nickel catalyst under the action of the reaction medium are studied via scanning electron microscopy, thermal analysis, X-ray diffraction, and conductometry. It is shown that the conversion of isopropanol into acetone through the dehydrogenation reaction is accompanied by a loosening of the initial homogeneous globular structure of the catalyst to form nickel nanoclusters. Active sites in the alcohol conversion reactions are nickel ions in different states of oxidation and cationic and anionic vacancies.

Electron properties of the system of Ni on kieselguhr

The electron properties of industrial nickel-kieselguhr catalyst under the action of reaction, oxidation, and reduction media are analyzed. As was determined after in situ conductometric studies of the surface of Ni/kieselguhr industrial catalyst, the electron properties on the Ni/NiO/SiO2 interface change, due to the nature of both phases: the surface of the catalyst and the given medium (C1–C4 aliphatic alcohols, oxygen or hydrogen). The mechanism of the observed changes, which determine the activity of Ni/kieselguhr catalyst in the transformations of aliphatic alcohols, is considered.

Effect of the method of preparation on the activity of nickel—Kieselguhr catalyst for vegetable oil hydrogenation

Nickel—Kieselguhr catalysts have been prepared by four different methods: direct impregnation, room temperature adsorption from basic (pH 11) solution and precipitation—deposition at 80°C from high pH (11) and low pH (6) solutions. The activity of the catalysts reduced at different temperatures has been measured in sunflower-seed oil hydrogenation. The differences found have been related with metal—support interaction. In this interaction, the determining step was the activation or even solution of the biogenic amorphous silica constituting the gel, and the further formation of a mixture of different nickel—hydrosilicate compounds. In this compound, Ni 3(OH) x (Si 2O 4) y , x and y depend on the method of preparation, higher pH resulting in higher y values. As a consequence, reduction temperature must be applied to the precursors according to the intermediate compound formed. XRD, XPS, IR and thermal analysis (T-reduction and T-oxidation) were used to elucidate the nature of the compounds obtained.

Hydrocarbon hydrogenolysis on nickel-tin catalysts

Hydrogenolysis of ethane, n-hexane and cyclohexane has been studied on nickel-kieselguhr catalysts modified by organic and inorganic compounds of tin. Tin additives decrease nickel reactivity with respect to C−C dissociation, which is ascribed to the formation of surface intermetallides on the catalyst.

Cyclohexane dehydrogenation on a nickel catalyst: Kinetics and catalyst fouling

AbstractThe main reaction and deactivation kinetics of cyclohexane dehydrogenation in the presence of hydrogen has been investigated at atmospheric pressure over a nickel kieselguhr catalyst in the temperature range 583–623 K. The rate of reaction for the fresh catalyst increased with increasing temperature, cyclohexane and hydrogen partial pressures whereas it decreased with an increase in the benzene partial pressure. The experimental data could be adequately modelled by a power law rate expression. The catalyst activity decreased with run time due to catalyst fouling by coke deposition. The rate of deactivation was independent of cyclohexane partial pressure, increased with increasing benzene concentration and decreased with increasing hydrogen partial pressure. It is postulated that coke is most likely formed by the successive dehydrogenation of benzene.

Adsorption characteristics of nitric oxide on various adsorbents determined by gas—solid chromatography

The adsorption of nitric oxide on 13X and 5A molecular sieves, alumina (boehmite) and nickel—kieselguhr and copper oxide—zinc oxide catalysts was studied by using a chromatographic technique. Moment analysis was used for determining the adsorption equilibrium constant K A. The nitric oxide is purely physically adsorbed on 13X molecular sieve and alumina in the ranges of temperature between 50 and 100 °C and between −8 and 50 °C respectively. The adsorption capacities of 13X molecular sieve and alumina are 0.5 cm 3 g −1 and 1.0 cm 3 g −1 respectively at 50 °C. The nitric oxide reacts with 5A molecular sieve and changes its adsorption capacity with time from 3.4 cm 3 g −1 for fresh adsorbent at 100 °C. For the nickel—kieselguhr catalyst the adsorption of nitric oxide at 50 °C and 110 °C takes place on two kinds of active sites with slow and fast reversible adsorption respectively. The total equilibrium constant, for fast and slow adsorption, is 0.90 cm 3 g −1 at 50 °C and 0.32 cm 3 g −1 at 110 °C. The nitric oxide reacts with the copper oxide—zinc oxide catalyst between 50 and 200 °C and changes the physical properties of the bed probably as a result of shrinkage of the particles. Therefore, quantitative data could not be obtained for this system.

Gas phase hydrogenation of benzene on supported nickel catalyst

The kinetics of benzene hydrogenation over a nickel-kieselguhr catalyst was studied in a differential flow microreactor. Temperatures ranged from 392.2 to 468.2 K, benzene partial pressures from 22.66 to 280 Pa, hydrogen partial pressures from 72.39 to 122.79 kPa, and cyclohexane partial pressures from 5.33 to 40 Pa. Cyclohexane was the only product of the reaction. The results were consistent with a mechanism in which all hydrogen addition steps were assumed to have the same rate constant and to form a set of slow steps. This mechanism could predict the maximum in the hydrogenation rate observed at about 458 K. A temperature-programmed desorption study of hydrogen chemisorbed on the catalyst indicated a number of desorption peaks between 358 and 600 K, one of which was coincident with the rate maximum.

Hydrogenation of Maleic Anhydride by Nickel-Kieselguhr Catalyst

A kinetic study of the hydrogenation of maleic anhydride over nickelcatalyst supported on kieselguhr was carried out, in order to elucidate the reaction mechanism and the reason why tetrahydrofuran or r-butyrolactone can not be obtained in high yield. The reactions were carried out batchwise under the following conditions temperature 180.y300C, pressure 120A 150 kg/cm2, and catalyst concentration 10 Wt%. Reactions of suecinic anhydride and succinic acid were alsostudied to con relementary processes.Reactions from maleic anhydride and succinic anhydride appear to proceed through different reaction schemes above 2500C, At low temperatures, the production of succinic acid is thermodynamically favorabie, but succinic acid was not hydrogenated to 7-butyrolactone. On the other hand, at high temperatures, the production of polymeric residue was predominant owing to the double bond of maleic anhydride.When the two-step hydrogenation method was applied, the yield of r-butyrolactone from maleic anhydride becameas high as in the case of the reaction of succinic anhydride. How, .ever, the tetrahydrofuran yield was very low even in this case.

Side-reactions in the Hydrogenation of 2-Ethylhexanal

The liquid phase hydrogenation of 2-ethylhexanal was carried out with the nickel-kieselguhr catalyst under the high pressure of hydrogen to identify the by-products, and to investigate the effects of the reaction conditions and some additives on the side-reaction.It was confirmed that 2-ethylhexanal (di-2-ethylhexyl) acetal was produced during 2-ethylhexanal hydrogenation and the yield of the acetal increased during the hydrogenation up to a maximum value at a point of 60∼70% conversion of aldehyde, and then decreased.The yield of bis-(2-ethylhexyl)ether increased with increase in the reaction temperature, that of the acetal decreasing. This reason was discussed in the paper. This side-reaction was promoted by acids contained in 2-ethylhexanal, but was supressed by water.

Kinetic Studies on Hydrogenation of 2-Ethylhexanal and Its Side Reactions

In the liquid-phase hydrogenation of 2-ethylhexanal over nickel-kieselguhr under pressure, 2-ethylhexanal(di-2-ethylhexyl) acetal is produced in the equilibrium state between 2-ethylhexanal and 2-ethylhexanol, as shown in the following scheme; [2-ethylhexanal] + 2[2-ethylhexanol] [2-ethylhexanal (di-2-ethylhexyl) acetal] + [H2O] Equilibrium constant of the acetal formation was measured at various temperatures and the enthalpy of formation was found to be -10.6 kcal/mol. It was also found that the hydrogenolysis reaction of 2-ethylhexanal(di-2-ethylhexyl)acetal over the nickel-kieselguhr catalyst is of the first order reaction and activation energy of the reaction is about 10.2 kcal/mol. Effect of organic acids and water as additives on the reaction rate of 2-ethylhexanal hydrogenation and on its side reaction was studied.

Hydrogenolysis of alcohols: III. Effect of supports on reduced nickel oxide for the conversion of alcohols to ethers

Catalysts prepared from nickel oxide deposited on kieselguhr, silica, silicaalumina, and alumina were reduced and studied for the conversion of primary alcohols. The alcohols studied were n-propanol, n-butanol, 2-methylbutanol, and 2,2-dimethylbutanol (neopentyl alcohol). The exepriments were made in a pulse reactor in the presence of a flow of hydrogen, at atmospheric pressure and at about 190 °. Three main reactions occur in the presence of a nickel-kieselguhr catalyst: (1) reductive dehydroxymethylation, (2) reductive dehydroxylation, and (3) ether formation. The last two reactions are related to the intrinsic acidic sites of the catalyst. Nickel-kieselguhr catalyst containing 6–10% of nickel gave in the case of n-butanol 73% conversion, with 72 mole % of di- n-butyl ether in the product. The presence of Na + in the catalyst inhibits the formation of ethers, while the dehydroxymethylation reaction increases. A continuous flow reaction at 190 ° demonstrated that nickel-kieselguhr catalyst containing 6% of nickel shows no deterioration after 16 hr of use. At 170 °, with a hydrogen to alcohol ratio of 10 and LHSV of 2, n-butanol reacted to the extent of 89%, with 91% yield of di- n-butyl ether.

Hydrogenolysis of alcohols: IV. Dehydration of cis- and trans-1,4-cyclohexanediol over nickel-kieselguhr catalyst: Contribution to the mechanism of ether formation

Hydrogenolysis of alcohols: IV. Dehydration of cis- and trans-1,4-cyclohexanediol over nickel-kieselguhr catalyst: Contribution to the mechanism of ether formation

Hydrogenolysis: I. Nickel-kieselguhr as catalyst for the conversion of alcohols to ethers and hydrocarbons

The hydrogenolysis of alcohols in the presence of nickel-kieselguhr catalysts has been investigated in a micropulse reactor at 150–190 ° and at atmospheric pressure. Three main reactions occurred with primary aliphatic alcohols: reductive dehydroxymethylation, dehydroxylation, and the formation of ethers. The nickel-catalyzed conversion of alcohols to ethers is a novel reaction and can be applied even for the synthesis of neopentyl ether. The methods of preparation of nickel-kieselguhr affects the composition of the products. For the preferential formation of ethers the catalyst was prepared by precipitating the nickel from an aqueous nickel nitrate solution with ammonium carbonate. When potassium carbonate was used as the precipitating agent the yield of ether was lower. The intrinsic acidic sites of the catalyst appear to be responsible for the reductive dehydroxylation and for the formation of the ethers. Kieselguhr as such was not a catalyst for these reactions, while a nonsupported nickel under certain conditions could influence the ether formation.

Kinetics of heterogeneous liquid hydrogenation under non-agitation (significance of agitation and the role of gas-liquid interface)

It was confirmed that even when not applying forced agitation, the rate determining step is the catalytic hydrogenation of ester on a nickel-kieselguhr catalyst and not a spontaneous transportation of the reactants, since the reaction is faster, being zero order with respect to the consumption of substrates, and there is preferential hydrogenation of ethyl linoleate to ethyl oleate. A far faster consumption of hydrogen was observed by the use of a platinum catalyst.State of the catalyst in liquid, suspension, or sedimentation, did not give any effect on the rate. No difference was found in the above phenomena under agitation, except for higher hydrogenation rate.Under this transferral equilibrium, the agitation effect is illustrated in terms of the role of liquid surface, where extra high concentration of hydrogen exists as the surface excess.The rotational agitation used in the present experiment may cause closer approach of more catalysts to the enlarged liquid surface region.Hydrogenation of p-nitrophenol over nickel-catalyst was also controlled by catalysis even under non-agitation.

Hydrogen and deuterium exchange of polypropylene

Abstract“Isotactic” and “atactic” polypropylenes in cyclohexane solution have been exchanged with hydrogen and deuterium in the presence of a large‐pore‐size nickel—kieselguhr catalyst. The resulting polymers were freed from catalyst, precipitated, pressed into films, and the density and stiffness determined. If the “isotactic” polymer were actually stereoregular, it would be expected from studies of model compounds that racemization of the tertiary carbon atoms in the chain would occur upon exchange. The racemization of the polymer would lead to a less “isotactic” polymer, and a drop in density and stiffness. The deuterium content of the polymer was determined by the refractive index of the water of combustion. The exchange values were as high as 3.0%. If all this deuterium were in the tertiary positions, about 18% of the tertiary carbons in the chain would be racemized. However, no detectable loss of stiffness or density occurred. This work failed to confirm the theory of isotacticity. The results, although no conclusive, seem to cast doubt on the theory.

On the Reduction Process of Nickel Kieselguhr Catalysts

酸化ニッケルケイソウ土触媒を260°～470℃において0.5～8時間水素還元し磁気測定をした。1/I対(1/H)0.87プロットの外挿より飽和磁化を求め, 磁化曲線の実験式中のパラメーターβ を決定した。400℃C,8時間還元したものの飽和磁化を標準とし,他試料の飽和磁化との比を磁気的還元率fとする。fは脱酸素量から求めた還元率と一致する。fと還元温度との間には一定の還元時間においてつぎの関係が得られた。logf=A-1260/T(Aは還元時間による定数)β と-78℃における水素吸着量vとの間にほぼβ∝V3/2の関係が認められβ はニッケル粒子の大きさに関する値と考えられる。β は還元温度ならびに還元時間によって変化し, その時間的変化は対数則によって表わされた。また還元反応の活性化エネルギーとして約18kcal, 粒子成長の活性化エネルギーとして約30kcalを得た。

AN ACCURATE METHOD OF ANALYSIS FOR SMALL QUANTITIES OF ETHYLENE

A procedure is described for the accurate analysis of ethylene in mixtures of ethane and ethylene by hydrogenation over a nickel–kieselguhr catalyst. Samples of ethylene as small as 0.03 cc. in mixtures of the order of 1.5 cc. of gas at N.T.P. can be determined to an accuracy of about one half per cent. Results are reported over a range of mixtures.

Hydrogenation of Furfural and Furfuryl Alcohol. IV. Hydrogenation of Furfural into Furfaryl (Tetrahydrofurfuryl) Alcohol by the Combination of Copper Chromium Oxide Catalyst and Nickel Kieselguhr Catalyst

Abstract 1. Furfural was hydrogenated into furfuryl alcohol by using copper chromium oxide catalyst under high pressure. Then the product was further hydrogenated by adding nickel kieselguhr catalyst, without separation and purification of furfuryl alcohol. The hydrogenation proceeded rapidly and furfaryl alcohol about 83–84% of the theoretical yield was obtained. 2. Furfural was hydrgenated by using copper chromium oxide catalyst and nickel kieselguhr catalyst, which were prepared separately before use. The hydrogenation proceeded rapidly, and furfaryl alcohol, (about 74∼79% of the theoretical yield) was obtained, which is slightly lower than in the above procedure. 3. The mixture of Cu(OH)(NH4)(CrO4) and nickelcarbonate kieselguhr, mixed mechanically or in the state of precipitates, was used for the hydrogenation of furfural, after reducing it with hydrogen or after thermal decomposition without reduction. The results was less satisfactory compared with the above two procedures.

Synthesis and Octane Number of tert-Butyl Cyclohexane and 1,4-Di-tert-butyl Cyclohexane. Alkylation of Benzene with Isobutylene into tert-Butyl Benzene and p-Di-tert-butyl Benzene and their Hydrogenation

Abstract 1. Benzene has been alkylated with isobutylene using sulfuric acid of various concentrations, and some of the results of V. N. Ipatieff, B. B. Corson and H. Pines have been reconfirmed. The alkylation takes place predominantly with 91–96% sulfuric acid. 2. Using 91% sulfuric acid as catalyst, benzene has been alkylated with varied amount of isobutylene against benzene. The increase of the yield of tert-butyl benzene caused by the decrease of the amount of isobutylene against benzene is not remarkable, forming a considerable amount of p-di-tert-butyl benzene fraction. By the increase of the amount of isobutylene against benzene, the yield of p-di-tert-butyl benzene fraction increases to the main reaction product, with the decrease of tert-butyl benzene fraction. The reaction of excess isobutylene with benzene causes the mere polymerisation of isobutylene with 91% sulfuric acid to yield high-boiling olefinic polymer after complete alkylation of benzene. 3. tert-Butyl benzene and p-di-tert-butyl benzene have been readily hydrogenated into tert-butyl cyclohexane and 1,4-di-tert-butyl cyclohexane, respectively, using nickel-kieselguhr catalyst. 1,4-Di-tert-butyl cyclohexane is a mixture of cis and trans isomers, and is partially crystal？ised at room temperature and melts completely at 31°C. 4. Octane numbers. of 1,4-di-tert-butyl cyclohexane, tert-butyl cyclohexane and the high boiling aromatic hydrocarbon CF2R have been measured. 1,4-Di-tert-butyl cyclohexane has high octane numbers as predicted, the 20% blending octane number amounting to 113. It has the flash point of 80.5°C., and is highly soluble in hydrocarbones, and there？ore may be used as a constituent of safety fuels.