Dénes Kalló

Fuel purpose hydrotreating of sunflower oil on CoMo/Al2O3 catalyst

The importance of the economical production and usage of new generation biofuels, the so-called bio gas oil (paraffins from triglycerides) and the results of the investigation for their productability on the CoMo/Al(2)O(3) catalyst, which was activated by reduction, are presented. The conversion of triglycerides, the yield of total organic fractions and the target product, furthermore the type and ratio of deoxygenation reactions were determined as a function of process parameters. The advantageous process parameters were found (380 degrees C, 40-60 bar, 500-600 Nm(3)/m(3) H(2)/sunflower oil ratio, 1.0 h(-1)), where the conversion of triglycerides was 100% and the yield of the target fraction [high paraffin containing (>99%) gas oil boiling range product] was relatively high (73.7-73.9%). The deoxygenation of triglycerides the reduction as well as the decarboxylation/decarbonylation reactions took place. The yield of the target fractions did not achieve the theoretical values (81.4-86.5%). That is why it is necessary to separate the target fraction and recirculate the heavy fraction.

Kinetics of hydroisomerization of C5-C7 alkanes and their mixtures over platinum containing mordenite

The hydroisomerization of n-pentane (n-C5), n-hexane (n-C6), n-heptane (n-C7), cyclohexane (c-C6) and their binary mixtures, n-C5/n-C6, n-C6/n-C7, n-C6/c-C6, was investigated over platinum loaded hydrogen mordenite catalyst at 180–220 ◦ C, 5–40 bar total pressure and hydrogen to hydrocarbon molar ratios 1–20. The apparent activation energies of isomerization are 147, 123, 118 and 114 kJ/mol in case of n-C5, n-C6, n-C7 and c-C6, respectively. The reaction orders in alkane up to 4 bar are 0.33, 0.39, 0.15 and 0.18, as well as the reaction orders in hydrogen up to 36 bar are −0.81, −0.65, −1.08 and −0.57 for n-C5, n-C6, n-C7 and c-C6, respectively. Rate equations were derived and parameters involved determined for the isomerization of pure paraffins. Kinetic results of n-C5, n-C6 and c-C6 in lower pressure range (palkane, pH2 ≤ 4 bar) suggest that the isomerization reaction on acid sites is rate-determining step. But in the case of n-C7 or at higher pressures of n-C6 and c-C6 (pH2 ≥ 20 bar, palkane > 5 bar approximately), the zeolite micropore is getting filled with reactants resulting in diffusional inhibition. Experimental data for binary mixtures showed that the reaction rate of both components decreased on mixing. The component having higher boiling point exerts higher inhibiting effect on the hydroisomerization of more volatile alkane than inversely. Kinetic equations for binary mixtures were also proposed.

Investigation of the production of high quality biogasoil from pre-hydrogenated vegetable oils over Pt/SAPO-11/Al2O3

Abstract A novel field of the catalytic application of Pt/SAPO-11 catalysts for the isomerization of pre-hydrogenated sunflower oils aiming the production of diesel fuel components is presented. Experiments were carried out over 0.2-1.0%Pt/ SAPO-11 catalysts at 280-380°C, 30-80 bar; LHSVs of 1.0-4.0 h –1 , H 2 /feed of 250-400 Nm 3 /m 3 . Results indicated that the yield of biogasoils obtained under favorable process conditions was >88%, the ratio of i -/ n -paraffins was 3.2-6.8, the cetane numbers were 79-85 units and the cold filter plugging point (CFPP) values were between –19– −16°C. These are excellent blend stocks of diesel fuels.

Acidic and catalytic properties of hydrogen sodium mordenite

The acidity of H,Na mordenites prepared from Na mordenite by ion exchange with ammonium to different degrees followed by deammoniation at various temperatures has been studied by microcalorimetry and i.r. spectroscopy. The differential molar adsorption heat and the amount of NH 3 molecules adsorbed were considered as measures of acid strength and the number of acid sites, respectively. Heat of adsorption as a function of coverage shows a stepwise decrease. Sites with adsorption heats of ammonia of 100 and 170–185 kJ mol −1 proved to be Lewis acid centers, and those of 110–160 kJ mol −1 are Bronsted acid centers. Half of the latter are not accessible for m -xylene. The strong Lewis sites are active for m -xylene disproportionation and isomerization, while Bronsted acid sites of medium strength catalyse only m -xylene isomerization.

Para-selectivity of toluene ethylation over ZSM-5 catalysts

The title reaction was studied around 400 °C in an excess of toluene at atmospheric pressure when hydrogen was present in order to avoid coke formation. Space time, reaction temperature, catalyst pretreatment temperature, catalyst aging and poisoning with organic bases, and introduction of inorganic additives containing phosphorus and/or magnesium into the catalyst were varied. The change of yields and selectivities points to the primary formation of p-ethyltoluene in the course of ethylene addition. Secondary reactions are the isomerization to m-ethyltoluene and hydrodeethylation of ethyltoluenes. Disproportionation of toluene is a simultaneous transformation. The para-selectivity increased when the side reactions were suppressed by the reduction of Bronsted acidity. The effects of diffusion control can be disregarded.

Kinetic model of the chemical recycling of waste polyethylene into fuels

Tertiary recycling methods offer potential possibilities for the utilization of waste plastics. Thermal and catalytic degradation of low-density polyethylene wastes were studied in a batch reactor under mild cracking conditions to derive liquid cracking products of olefins and paraffins. Zeolite catalysts with different activities were studied: a commercial equilibrium FCC catalyst, an H form ZSM-5 catalyst, and a natural clinoptilolite containing rhyolite tuff. The catalytic processes could convert waste polymers into valuable hydrocarbons. The properties of products could be modified by the use of catalysts. The olefin content and the position of the olefinic double bonds were investigated with IR spectrometry. In the presence of catalysts the olefin content increased, and the terminal bonds migrated into internal positions. Furthermore the liquid products had lower average molecular weights than those obtained without catalysts. The activation energies of the cracking reactions with or without catalysts were determined. The apparent activation energy was lower in catalytic than that in thermal degradation. The cracking reaction rates were modelled and the reaction rate constant of each hydrocarbon type was calculated. The model gives a good approximation of the experimental results obtained from the degradation of LDPE waste in the presence and absence of catalysts. Under the studied parameters, liquids were formed with suitable properties for further uses (e.g. low sulphur content, low pour point).

Mechanism of 1-butene hydration over acidic zeolite and ion-exchange resin catalysts

Abstract Vapour-phase hydration of 1-butene at atmospheric pressure above 373 K shows similar features on both H-clinoptilolite and sulphonic acid ion-exchange resin: the initial reaction rate linearly increases with the partial pressure of 1 -butene and passes through a maximum as a function of water pressure. Kinetics was evaluated accordingly. A decrease in the 1-butene isomerization rate indicated that under hydration conditions more than 99.9% of the acidic sites are hydrated. For the hydration, however, hydroxonium ions are the active centres where an adsorbed water molecule reacts with gasphase 1-butene in the rate determining step. The equilibrated desorption of secondary butanol ends the reaction. The kinetic inhibition by butanol can be suppressed with water. Above ca. 0.2 bar water pressure inactive polyhydrated hydroxonium ions are formed.

The effect of adamantane addition on the conversion of n-heptane over H- and Pt/H-zeolites

H- and Pt/H-forms of zeolites Y and mordenite were studied in atmospheric n-heptane (n-C7) hydroconversion at 423–443 K. Adamantane (Ad) additive was found to increase the isomerization and suppress the cracking activity of the H-zeolites. It had minor or no influence on the hydroconversion activity of the Pt/H-forms. Species obtained from Ad adsorbed on zeolites were examined by IR spectroscopy. The Ad-saturated samples (Ad/H-zeolites) were boiled with n-C7 and the liquid phase was analyzed by GC–MS. Results suggested that Ad was activated over the H-zeolites for further reactions via protolysis of its C–H bonds. The Ad and the formed adamantyl carbenium ions (Ad + ) participated in hydride transfer processes. In these processes, the Ad remained unconverted and acted as co-catalyst increasing n-C7 isomerization selectivity. Results suggested that under conditions of n-C7 hydroconversion no or minor amount of Ad + was generated on the Pt/H-zeolite catalysts. Over strong acid mordenite bulky carbocations and Ad compounds were rapidly formed contributing to the decay of the activity in n-C7 conversion.

The activation of CD4 for H/D exchange over H-zeolites

The H/D exchange was studied between CD4 and H-zeolites using pulsed a microcatalytic reactor and MS analysis. Methane-d3 was the only exchange product, while a large fraction of the reactant was retained by the zeolite. The apparent activation energies (Ea) were determined for CHD3 production assuming first-order reaction kinetics. The Ea was close to 80 kJ mol-1 over the H-ZSM-5 and H-mordenite, and about 50 kJ mol-1 over H-beta. Results suggested that, at the low methane loading applied, the H/D exchange was initiated predominantly by heterolytic dissociation of CD4 to CD3δ- and Dδ+ over Lewis acid-Lewis base pair sites.

Adsorption of acetylene and water on zeolites resulting in hydration to acetaldehyde

Adsorption of water and acetylene on Cd forms of LTA, X-, and Y,FAU, ERI, CHA, PHI, MOR, MFI, and clinoptilolite active in the catalytic hydration of acetylene at 453 K and the adsorption of acetylene on inactive H, Na, Co, and La forms of Y,FAU were studied with i.r. spectroscopy at 298 K. Acetylene (1) adsorbs on acidic OH groups; (2) is weakly bound to cations (νC=C = 1,958 cm−1); (3) forms cadmium acetylide (νC=C = 1,947 cm−1); and (4) is linked in side-on configuration to Cd2+ (νC=C = 1,930 cm−1). Water dissociated heterolytically was found to react with adsorbed acetylene. Formation of adsorbed acetaldehyde was observed on Cd zeolite catalysts as well as on catalytically inactive forms of faujasite but not on H-F,FAU