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• New technology for high temperature three-phase Fischer-Tropsch synthesis. • Light liquid hydrocarbons enriched with α-olefins (up to 50% wt). • CO conversion of about 80% (per pass), selectivity toward liquid products of 85%, and C 5+ productivity of 600 g / h kg Me. TIPS RAS (Russia) has developed a new technology for high temperature three-phase Fischer-Tropsch synthesis. This technology is based on an original nanosized iron catalyst and a new reactor type. Producing light liquid hydrocarbons enriched with α-olefins (up to 50% wt) is the main distinction from industrial slurry-technologies. Yield of these products is about 140 g per 1 cubic meter of syngas. This technology is tested in a pilot plant with capacity of up to 2 liters of liquid hydrocarbons per day. Project indexes are CO conversion of about 80% (per pass), selectivity toward liquid products of 85%, and C 5+ productivity of 600 g / h kg Me. [ABSTRACT FROM AUTHOR]

The effect of process conditions on product selectivity of Fischer–Tropsch synthesis (FTS) over industrial iron-based catalyst (100 Fe/5 Cu/4.2 K/25 SiO 2 ) was studied in a 1-L stirred tank slurry reactor. Experiments were performed over a range of different reaction conditions, including three temperatures ( T = 493, 513 and 533 K), four pressures ( P = 0.8, 1.5, 2.25 and 2.5 MPa), two synthesis gas feed molar ratios (H 2 /CO = 0.67 and 2) and gas space velocity from 0.52 to 23.5 Ndm 3 /g-Fe/h. The effect of process conditions on reaction pathways of FTS and secondary 1-olefin reactions was analyzed by comparing product selectivities, chain growth probabilities and ratios of main products (n-paraffin, 1- and 2-olefin). Reduction of methane production and increase of C 5+ products was achieved by decreasing temperature, inlet H 2 /CO ratio and/or increasing pressure. Overall selectivity toward methane and C 5+ did not show significant changes with variations in residence time. All of the product selectivity variations were shown to be related to changes in chain length dependent growth probabilities. [ABSTRACT FROM AUTHOR]

A series of carbon nanofibres supported Cu/ZrO 2 /Nb 2 O 5 catalyst synthesized by deposition precipitation method were extensively investigated in relation to their performance in hydrogenation of CO 2 to methanol. In order to study the promotion effect of niobium, catalysts were loaded with 0.4, 0.8 and 1.2 wt.% of Nb 2 O 5 . Incorporation of Nb 2 O 5 facilitated copper reduction by exhibiting a shift of highly reduced copper peak to lower temperature. Likewise, surface enrichment of copper was also enhanced by introduction of Nb 2 O 5 to the catalysts. Activity studies of Nb 2 O 5 doped Cu/ZrO 2 catalysts were evaluated in a slurry reactor with a CO 2 /H 2 gas mixture of 1:3 volume ratio, 180 o C temperature and 3.0 MPa total pressure. The highest activity was achieved with the incorporation of 0.8 wt.% of Nb 2 O 5 , illustrating the high degree of CuO crystallization on the surface of catalyst are beneficial for the generation of copper catalyst with enhanced activities. [ABSTRACT FROM AUTHOR]

Nano-iron carbides (NFeC), generated by a plasma spray technique, were used as-produced and promoted with potassium (K) and copper (Cu) in Fischer–Tropsch synthesis (FTS) in a 3-φ continuously stirred tank slurry reactor. NFeC particles were initially encapsulated in a carbon matrix to protect them from air-borne oxidation. This matrix was partially removed under reductive conditions as a pre-treatment of subsequent FTS reactions. Cu and K promoters were added to the catalyst by mixing Cu metallic powder and/or K 2 CO 3 powder with iron–oil suspension fed to the plasma. The reactants simulated the composition of synthesis gas produced by urban biomass gasification. At-line gas chromatography of the more volatile products and global liquid product analyses by micro-distillation provided the necessary data for mass balance, conversion and selectivity estimations. Also, an appropriate algorithm successfully estimated the ratio of FTS over water–gas shift (WGS) reactions extents. The results disclosed that this nano-powder, characterized by very low internal porosity, generated a liquid fuel that was lighter than other commercial catalysts under similar reaction severities but at a significantly lower catalyst load (9% of the mass of liquid). Increased catalyst loading in the slurry above a critical limit led to higher product water hold-up and, consequently, higher rates of catalyst deactivation. Conversion, selectivity and the Anderson–Schulz–Flory distribution probability of chain growth “ α ” were compiled and reported. Tests with Cu- and K-promoted catalysts showed a highly significant decrease of the catalyst deactivation rate, with CO and H 2 conversion increasing respectively to 82% and 44% from 35% and 30% obtained with no-doped catalyst. Moreover, CH 4 yield was reduced to 4.7% from 12%, and the WGS rate tripled. Finally, the absence of internal porosity in the catalyst facilitated the definition of process-operating conditions in which surface reaction kinetics was the controlling step. [ABSTRACT FROM AUTHOR]

Highlights: [•] Catalyst deactivation in slurry Fischer–Tropsch reactor coincides with carbon deposition. [•] Strongly adsorbed carbon species are constituted by olefins, paraffins, aldehydes, ketones and acids. [•] Aromatic aldehydes were detected under hydrogen poor conditions. [•] Carbon species located on the support are more reluctant to hydrogenation than those on metal particles. [Copyright &y& Elsevier]

Highlights: [•] Detailed kinetic model of FTS over promoted Co catalyst was developed. [•] Model was derived based on the CO-insertion mechanism and LHHW methodology. [•] Chain length dependent desorption of 1-olefins is used to explain the increase in growth probability and decrease in olefin-to-paraffin ratio with increase in carbon number. [•] Physical meaningfulness of the model and its parameters was verified. [•] A good prediction of the product formation rates for C1–15 n-paraffins and C2–15 1-olefins for a range of process conditions was obtained. [Copyright &y& Elsevier]

Highlights: [•] Cobalt catalyst deactivation is modeled in slurry Fischer–Tropsch reactor. [•] Sintering mechanism involves cobalt surface oxidation followed by cobalt particle migration and coalescence. [•] Rate of sintering depends on the ratio of H2O and H2 concentrations in liquid phase. [•] The presence of water in the syngas accelerates cobalt sintering. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a comparative study of Fischer–Tropsch synthesis in single channel milli-fixed bed, conventional centimetric fixed bed and slurry stirred tank reactors. In the three reactors, the catalytic measurements were carried out with the same conventional platinum-promoted alumina supported cobalt catalyst at 493K and 20bar using a stoichiometric syngas ratio (H2/CO=2). The single channel milli-fixed bed reactor displays a higher initial Fischer–Tropsch reaction rate than the conventional centimetric fixed bed reactor. This effect was assigned to a better temperature control and less significant catalyst deactivation during the startup of the single channel milli-fixed bed reactor. The slurry stirred tank reactor shows much lower hydrocarbon productivity than the milli- and centimetric fixed bed reactors, which is probably due to incomplete catalyst reduction. A considerable catalyst deactivation due to the uncontrolled temperature hike can occur during the reactor startup in the conventional centimetric fixed bed reactor. The slurry stirred tank and milli-fixed bed reactors show similar apparent deactivation behavior. [Copyright &y& Elsevier]

Abstract: The photocatalytic inactivation of Escherichia coli bacteria with titanium dioxide immobilised in a fixed-bed reactor has been studied and compared with the results obtained using aqueous titania suspensions. In both cases, the photocatalytic inactivation has been successfully achieved, reaching a 6-log decrease in the concentration of bacteria. The slurry system shows a higher inactivation rate at the beginning of the reaction that decreases progressively, whereas the fixed-bed reactor increases the inactivation rate as the irradiation time increases, leading both catalytic systems to comparable irradiation times for the total inactivation of bacteria, i.e. concentration below the detection limit. This opposite trend seems to be related to differences in the bacteria–TiO2 interaction, being also observed that the fixed-bed catalytic system is less affected by the competition for the oxidant species of byproducts released after the bacterial cell lysis. Epifluorescence microscopy pictures taken after a dual DAPI/PI staining membrane permeability assay provide mechanistic insights into this different behaviour, showing for the fixed-bed experiments an increase in the damaged bacteria from the very beginning of the reaction, whereas for the slurry system they were not observed until longer irradiation exposition is achieved. These results suggest as hypothesis that although in absolute terms the number of hydroxyl radical attacks could be even lower in the immobilised systems, the damages are more concentrated on the area in which the bacteria–TiO2 interaction takes place. Although the fixed-bed reactor requires comparable irradiation time for total inactivation of bacteria than that corresponding to the slurry system, it shows minor deactivation and allows the continuous operation without the need of particles removal, making this immobilised system a good alternative to successfully scale-up the photocatalytic disinfection technology. [Copyright &y& Elsevier]

Abstract: An evaluative investigation of the Fischer–Tropsch performance of two catalysts (20%Co/Al2O3 and 10%Co:10%Mo/Al2O3) has been carried out in a slurry reactor at 2MPa and 220–260°C. The addition of Mo to the Co-catalyst significantly increased the acid-site strength suggesting strong electron withdrawing character in the Co-Mo catalyst. Analysis of steady-state rate data however, indicates that the FT reaction proceeds via a similar mechanism on both catalysts (carbide mechanism with hydrogenation of surface precursors as the rate-determining step). Although chain growth, α, on both catalysts were comparable (α ≅0.6), stronger CH2 adsorption on the Co-Mo catalyst and lower surface concentration of hydrogen adatoms as a result of increased acid-site strength was responsible for the lower individual hydrocarbons production rate compared to the Co catalyst. The activation energy, E, for Co (96.6kJmol−1), is also smaller than the estimate for the Co-Mo catalyst (112kJmol−1). Transient hydrocarbon rate profiles on each catalyst are indicative of first-order processes, however the associated surface time constants are higher for alkanes than alkenes on individual catalysts. Even so, for each homologous class, surface time constants for paraffins are greater for Co-Mo than Co, indicative that the adsorption of CH2 species on the Co-Mo surface is stronger than on the monometallic Co catalyst. [Copyright &y& Elsevier]

Abstract: Fluidized bed and slurry reactors were employed to increase the CO2 conversion and desirable product selectivity in the direct hydrogenation of CO2 to hydrocarbons over K-promoted iron catalysts, as it is beneficial for the removal of heat generated due to highly exothermic nature of the reaction. The iron catalysts (Fe-K/Al2O3 and Fe-Cu-Al-K) were characterized by BET surface area, CO2 and H2 chemisorption, temperature-programmed reduction (TPR), X-ray diffraction (XRD) and temperature-programmed hydrogenation (TPH). The results of TPR and TPH study clearly indicated that co-precipitated Fe-Cu-Al-K catalyst has much higher reducibility and catalytic activity of CO2 hydrogenation at low temperature than Fe-K/Al2O3. The performance of fluidized bed or slurry reactors was superior to that of fixed bed reactor for the CO2 hydrogenation over Fe-Cu-Al-K catalyst in terms of CO2 conversion and hydrocarbon productivity. Moreover, light olefins and heavy hydrocarbons were selectively synthesized in fluidized bed and slurry reactors, respectively. The optimum operation conditions and the effects of operating variables on the CO2 conversion and its product distribution in these catalytic reactors were also discussed. [Copyright &y& Elsevier]

Abstract: A highly stable and active Fe-Mn catalyst for slurry Fischer–Tropsch synthesis (FTS) was prepared and scaled up for the application in the industrial pilot plant at Institute of Coal Chemistry (ICC), Chinese Academy of Sciences (CAS). One Lab-scale catalyst and one scaled-up catalyst are introduced in the present paper. The particle size of the Lab-scale catalyst is about 5–15μm, while it is increased to 30–90μm for the scaled-up catalyst. Simultaneously, the morphology of the catalyst was greatly improved after the catalyst being scaled up. Both the Lab-scale and scale-up catalysts show high FTS activity. CO conversion of the Lab-scale catalyst and the scaled-up one are over 70.0% (H2/CO=0.67, 275°C, 1.5MPa and 3000h−1) and 55.0% (H2/CO=0.67, 260°C, 1.5MPa and 2000h−1), respectively. The catalysts also possess excellent stability, no obvious deactivation was observed during stable run of 4200h and 1200h on stream for the two catalysts. However, the Lab-scale catalyst produced more methane (about 8–10wt%) and C2–4 (22–30wt%) and less C5+ hydrocarbon (55–70wt%). Meanwhile, the hydrocarbon distribution of the catalyst was greatly improved for after the catalyst being scaled up, and the distribution of hydrocarbon products become much preferable. The selectivity to methane was well controlled at about 5wt%, and the sum of and was increased to 91–93wt%. On the whole, the scaled-up catalyst satisfies the requirements of the application for FTS in the industrial pilot plant of slurry bubble column reactor (SBCR) at ICC, CAS. [Copyright &y& Elsevier]