Miron V. Landau

Deep hydrotreating of middle distillates from crude and shale oils

Abstract The potential scientific and technological solutions to the problems that appear as a result of shifting the hydrotreating of crude oil middle distillates and shale oils from the ‘normal’ to the ‘deep’ mode are considered on the basis of the reactivities and transformation routes of the least-reactive sulfur-, nitrogen-, and oxygen-containing compounds. The efficiency of selecting the optimal feedstock, increasing the process severity, improving the catalysts activity, and using alternative catalytic routes are compared, taking into account the specific issues related to deep hydrodesulfurization/hydrodenitrogenation/ hydrodeoxygenation, i.e., chemical aspects, kinetics and catalysts.

Mesoporous alumina catalytic material prepared by grafting wide-pore MCM-41 with an alumina multilayer

Abstract An alumina multilayer grafted on the surface of MCM-41 produced a mesoporous material with the surface chemical functionality of alumina. The starting MCM-41 material (WPMCM) with a wide pore size distribution, a surface area of 858 m 2 /g, an average pore diameter of 8.2 nm and a pore volume of 1.75 cm 3 /g was synthesized by expanding the cetyltrimethylammonium chloride (CTAC) surfactant micelles with mesitylene at a high solubilizant/CTAC ratio of 10. Successive grafting consisting of aluminum butoxide anchoring followed by hydrolysis and calcination steps yielded a gradual increase of the aluminum content in WPMCM. Tetrahedral Al in the silica pore walls and clusters of a separate octahedral Al alumina phase were identified. Four grafting cycles produced a material with a surface area of 542 m 2 /g and a mean pore diameter of 4 nm containing 38 wt.% Al 2 O 3 that displayed chemical surface functionality of pure alumina. The activity of this material in the alkylation of phenol with methanol was 2.3 times higher than the activity of a reference alumina (460 m 2 /g). The highest activity of grafted alumina in cumene cracking and isopropanol dehydration was achieved at 21 wt.% Al 2 O 3 . Independent measurements of surface charging in aqueous solution, of [Mo 7 O 24 ] 6− anions adsorption and of surface acidity indicated that the material grafted with alumina and the reference alumina display similar chemical functionality.

Using Sonochemical Methods for the Preparation of Mesoporous Materials and for the Deposition of Catalysts into the Mesopores

Ultrasound radiation can be used to synthesize a variety of mesporous materials. The reaction time is considerably shorter than the conventional methods. Ultrasonic waves can be further used for the insertion of amorphous nanosized catalysts into the mesopores. A detailed study demonstrates that the nanoparticles are deposited as a monolayer on the inner mesopores walls without blocking them. When the ultrasonically prepared catalyst/mesoporous-subtrate composite is used in catalysis a high conversion into product is obtained.

Structure–Function Relations in Supported Ni–W Sulfide Hydrogenation Catalysts

Ni–W catalysts were prepared by impregnation of commercial γ-alumina and silica supports. The sulfidation, performed directly after drying at 100°C, yielded fully sulfided Ni–W species on both supports (SEM-EDAX, XPS, XRD). At optimal metals loading (∼50 wt% NiO + WO3, Ni/W = 2), the sulfided catalysts had similar texture (N2 adsorption) and displayed similar activity in dibenzothiophene hydrodesulfurization (DBT HDS), while the activity of the Ni–W/SiO2 catalyst in toluene hydrogenation (HYD) was six times higher than that of Ni–W/Al2O3. This is due to the more than two times higher WS2 slabs stacking number in Ni–W/SiO2 compared with Ni–W/Al2O3 (XRD, HR-TEM), yielding stronger adsorption of toluene (TPD).

Selectivity in heterogeneous catalytic processes

Abstract The selectivity of several catalytic systems was studied. Shape selectivity of Pt on carbon-fiber catalysts was demonstrated in the competitive hydrogenation of 1-hexene and cyclohexene and in the parallel dehydrogenation of cyclohexanol to cyclohexanone and phenol. Both reactions were carried out in a gas-phase fixed-bed reactor. Catalysts prepared on carbon fibers, containing pores with small constrictions (5 A) yielded significantly higher rates of hydrogenation of 1-hexene compared to those of cyclohexene and selectively produced cyclohexanone from cyclohexanol. Other catalysts, supported on carbon fibers with large constrictions (7 A) or activated carbon, displayed comparable rates of hydrogenation for both reactants and yielded cyclohexanone as well as phenol from cyclohexanol. Nitration of o -xylene with nitrogen dioxide was carried out in the gas phase over a series of solid acid catalysts packed in a fixed bed. Several zeolites, supported sulfuric acid, and sulfated zirconia were tested. Zeolite H-β was found to be the most active and selective catalyst for the production of 4-nitro- o -xylene. A preliminary kinetic model indicated that the selectivity to 4-nitro- o -xylene increased with decreasing concentration of nitrogen dioxide. Alkylation of phenol with methanol was performed on zeolites, supported sulfuric and phosphoric acids, and sulfated zirconia packed in a fixed-bed. The ratio of o - to c -alkylation, measured at 180°C and methanol to phenol feed molar ratio of unity, ranged from 4 with the supported acids to 2 with zeolite H-β. This ratio decreased with temperature. The ratio of o - to p -cresol changed from about 2 in zeolites in supported sulfuric acid and to 0.5 in phosphoric acid supported on carbon fibers.

Sustainable Production of Green Feed from Carbon Dioxide and Hydrogen

Carbon dioxide hydrogenation to form hydrocarbons was conducted on two iron-based catalysts, prepared according to procedures described in the literature, and on a new iron spinel catalyst. The CO2 conversion measured in a packed-bed reactor was limited to about 60% because of excessive amounts of water produced in this process. Switching to a system of three packed-bed reactors in series with interim removal of water and condensed hydrocarbons increased CO2 conversion to as much as 89%. The pure spinel catalyst displayed a significantly higher activity and selectivity than those of the other iron catalysts. This process produces a product called green feed, which is similar in composition to the product of a high-temperature, iron-based Fischer–Tropsch process from syngas. The green feed can be readily converted into renewable fuels by well-established technologies.

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.

From macroalgae to liquid fuel via waste-water remediation, hydrothermal upgrading, carbon dioxide hydrogenation and hydrotreating

This article showcases a proof-of-concept in the production of high quality renewable biofuel from algae. Here, we introduce a path combining a number of approaches that, when integrated as a whole, create a process that takes algae grown in waste-water through to a liquid fuel containing fractions ready for blending with regular gasoline, jet fuel and diesel. With the overarching goal of reducing the nitrogen content invariably associated with whole algal biomass, we apply a number of approaches including (i) nutrient starvation to reduce the internal nitrogen of the freshwater alga Oedogonium (ii) continuous co-solvent (10 wt% n-heptane) hydrothermal liquefaction (HTL) to produce a non-polar biocrude containing <1 wt% N; (iii) blending the biocrude with green feed produced from the hydrogenation of CO2 to obtain <0.5 wt% N; (iv) hydrogenation and hydro-isomerization of the blend in two stages over nanodisperse silica-supported Ni2P (achieving 630 ppm N) and acidic zeolite-supported Pt catalysts respectively to produce a synthetic paraffinic mixture (SPM) containing 277 ppm N and 0.12% O. With the incorporation of renewable H2 (which can be from gasification of polar organics produced in the solvent HTL, or other renewable sources) and captured CO2 the process demonstrates a new and technically cohesive approach to the production of renewable, high-quality biofuels for demanding transport applications.

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.