M. Herskowitz

Dehydrogenation of propane on modified Pt/θ-alumina Performance in hydrogen and steam environment

Dehydrogenation of propane was carried out on several promoted Pt catalysts. The performance of the catalysts (activity, selectivity and coke formation) was compared in steam and hydrogen environment. Promoting Pt supported on θ-alumina with Sn and K is essential for developing high-performance catalysts. The combination of optimal catalyst composition and steam yields high activity and selectivity at low coke formation. Inferior results were measured with hydrogen as diluent. Characterization of catalysts using XPS, TEM and chemisorption methods supported the results of reaction data.

Medium-severity hydrotreating and hydrocracking of Israeli shale oil. 1. Novel catalyst systems

Abstract Novel catalysts were developed for the hydrodesulfurization, hydrodenitrogenation and hydrocracking of Israeli shale oil. They were designed to operate on feedstock containing a high level of sulfur and nitrogen. Two hydrotreating stages and one hydrocracking stage were performed in a batch reactor. High-activity catalysts with large macropores yielded 97 and 79% conversion of sulfur and nitrogen respectively in the first stage. 1 H and 13 C n.m.r. and nitrogen distribution measurements among the distillation cuts showed that nitrogen remaining after the first hydrotreating stage comprised low-molecular-weight heteroaromatics. A further reduction of the sulfur to 100–200 ppmw and nitrogen to 7–30 ppmw was obtained in the second stage using zeolite-containing catalysts. The major parameters affecting the catalyst performance were tested. A moderate temperature of 380°C and pressure of 15 MPa were used in both stages. A selective dual-zeolite hydrocracking catalyst in a third stage yielded 80% of the product in the naphtha boiling range.

Medium severity hydrotreating and hydrocracking of Israeli shale oil — II. Testing of novel catalyst systems in a trickle bed reactor

Hydrotreating Israeli shale oil at 150 atm, an LHSV of 0.5–1.5 h−1, a temperature of 340–400°C, and a hydrogen to oil ratio of 1500 NL L−1 was studied in a trickle-bed reactor pilot plant packed with two novel catalysts in series. The first catalyst was NiMo supported on wide-pore alumina and the second catalyst was CoMoCr supported on combined zeolite HY-alumina carrier. The desulfurization conversion was higher than 99% over the operating conditions tested while denitrogenation conversion varied over the range 74.3–99.9%. The pseudo-first-order denitrogenation rate constants measured at 380°C increased from 1.9 to 2.9 h−1 with increasing distillation temperatures of shale oil fractions from 380°C. The apparent activation energy decreased from 29.8 to 23.1 kcal mol−1. The effects of LHSV and temperature on the structure of shale oil components and hydrocarbons distribution was studied using 1H and 13C NMR and GC-MS methods. The yields of total liquid product, gasoline, jet and diesel fuels at 380°C and LHSV = 0.5 h−1 were 89.4, 9.3, 22.5 and 65.8 wt% of crude shale oil. The volume yield of liquid product per crude shale oil at those conditions was 106.9%. It contained 160 ppm sulfur and 80 ppm nitrogen. The quality parameters of motor fuels produced from shale oil by hydrotreating with the two-catalyst system meets certain specifications except gasoline, which displayed low Reid vapor pressure and RON 72. A 400 h stability test at 380°C indicated no catalysts deactivation.

Deep desulfurization of heavy atmospheric gas oil with CoMoAl catalysts effect of sulfur adsorption

Abstract The transient sulfur adsorption and reaction on partially sulfided and oxyregenerated Co Mo Al catalysts in the hydrodesulfurization of heavy atmospheric gas oil (HAGO) was studied in batch and trickle-bed reactors. All experiments were carried out at 360°C and 5.5 MPa. The contribution of sulfur adsorption to sulfur removal was significant in cases of 1000–1800 ppm sulfur in the feedstock. The sulfur level in hydrotreated HAGO was lowered by 50–350 ppm due to sulfur adsorption on the catalyst for periods of 20–50 h. The principle of regeneration and adsorption in a trickle bed has been proven. A model that describes the transient adsorption and reaction is proposed.

An algorithm for finding composition, molar volume and isochors of CO2-CH4 fluid inclusions from Th and Tfm (for Th < Tfm)

Abstract A modified Redlich-Kwong equation of state is used to calculate the solubility of CO 2 in methane at various temperatures and pressures. From the solubility of CO 2 in CH 4 at the triple point and at final melting ( T h T fm ), and the molar volume of solid CO 2 , the volume of solid at the triple point, and the molar volume of the inclusion can be calculated using a mass balance. The pressure at the melting point is calculated from the equation of state. The algorithm predicts composition, molar volume, pressure at final melting and the isochor pressure (for a given temperature of trapping) for CO 2 -CH 4 fluid inclusions for the case T h T fm , given T h , T fm and experimental data on P h and d co 2 (solid) at T h .

Medium severity hydrotreating and hydrocracking of Israeli shale oil. III. Hydrocracking of hydrotreated shale oil and its atmospheric residue for full conversion to motor fuels

Hydrocracking of hydrotreated Israeli shale oil and its atmospheric residue was studied at 50 atm hydrogen pressure, LHSV 0.5-4.4 h -1 , temperature 350°C and V H2 1500 Nl/l in a fixed bed reactor pilot plant with two Ni-Mo-zeolite catalysts based on mono-(HY + Al 2 O 3 ) and bizeolite (HY + H-ZSM-5 + Al 2 O 3 ) supports. Desulfurization and denitrogenation conversion of the feedstock was higher than 99.7% (sulfur content 134 ppm, nitrogen content 4.4 ppm) and it comprised 14 vol.% atmospheric residue boiling out at 360°C +. Hydrocracking of the whole hydrotreated shale oil yielded full conversion of atmospheric residue at LHSV = 2.75 h -1 with monozeolite catalyst (A) and at LHSV = 3.5 h -1 with biozeolite catalyst (B). The yield of liquid fuel at these conditions was 87.6 wt% with catalyst A versus 82.4 wt% with catalyst B. The contents of light naphtha ( < 100°C). heavy naphtha ( < 200°C) and jet fuel (160-280°C) in the liquid product were 10-15% higher with catalyst B compared with A. Hydrocracking at full residue conversion produced shifts of the hydrocarbon distributions to lighter molecules inside the hydrocarbon groups, decreased n-paraffins concentrations by isomerization and splitting to C 5 -. Hydrocracking of the atmospheric residue with catalyst A yielded full conversion into 360°C-products at LHSV = 0.5 h -1 . The only liquid product obtained in this case at 72.3% yield was naphtha with distillation patterns corresponding to gasoline specification. The nitrogen content in the liquid hydrocracking products at full conversion of atmospheric residue fraction of the shale oil was < 1 ppm and the sulfur content < 15 ppm.

Novel nitrogen containing heterogeneous catalysts for oxidative dehydrogenation of light paraffins

Abstract Novel nitrogen contained catalyst CoNx/Al2O3 yielded high performance in the oxidative dehydrogenation of propane and n-butane. 47.6 and 37.4 wt% yield of olefins at 82% butane and 76.7% propane conversion were measured at 600 °C. Ethylene and propylene were mainly formed at >400 °C via oxidative cracking of paraffins. XRD and XPS studies of the novel catalytic system indicate an essential modification of cobalt by nitrogen.

DESORPTION WITH CHEMICAL REACTION IN CONTACTING DEVICES

Chemical processes where a gas is absorbed into a liquid and reacts to give a product that desorbs back into the gas are quite common in the industry. In this study, the reaction between the absorbed gaseous reactant and a nonvolatile reactant is considered to be slow, fast or instantaneous, while the volatile product may react further in a slow reaction. Effects of various operating parameters such as the liquid and gas flow rates, the gas-liquid interfacial area and the coefficients for mass transfer are examined. Situations can arise where the absorbing gas reacts but the product diffuses completely to the bulk of the liquid, and the rate of desorption is null. The expressions presented here define conditions to avoid this situation and allow the calculation of the optimal design and operation of the gas-liquid contacting device

A comparative study of an MCM-41 anchored quaternary ammonium chloride/SnCl4 catalyst and its silica gel analogue

A novel reusable Lewis acid catalyst has been prepared by the heterogenization of a Lewis acid/tetrapropylammonium adduct; anchoring of tin chloride on quaternary ammonium chloride functionalized MCM-41 yielded a catalyst with higher activity compared to the corresponding silica analogue in terms of turnover rates and product yield in the Prins condensation of isobutene and formaldehyde to isoprenol.

Effects of gaseous and liquid components on rate of deep desulfurization of heavy atmospheric gas oil

Abstract The effects of concentrations of sulfur, nitrogen, bi-(BA) and monoaromatics (MA) in heavy atmospheric gas oil(HAGO), H2S and ammonia in gas phase on HDS rate at deep desulfuriation stage (Sin 1110-60 ppm) were studied with Co-Mo-Al and Ni-W-Si catalysts using HAGO with FBP of 390°C and initial sulfur content of 1.24 wt.%. The complete elimination of hydrogen sulfide, ammonia, polyaromatics and partial elimination of monoaromatics prior to the deep desulfurization stage increases the overall rate of deep HDS by a factor of about six.