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In everyday life, superior lithium-ion batteries (LIBs), with fast charging ability, have become valuable assets. The LIB performance of an anode composite copper cobalt tin sulphide (Cu2CoSnS4; CCTS) electrode, which was fabricated using a simple and easy hydrothermal method, was investigated. The electrochemical charge storage performance of the CCTS anode demonstrated sustainability, high-rate capability and efficiency. The CCTS anode exhibited a first discharge capacity of 914.5 mA h g−1 and an average specific capacity of 198.7 mA h g−1 in consecutive cycles at a current density of 0.1 A g−1. It had a capacity retention of ∼62.0% and a coulombic efficiency of more than 83% after over 100 cycles, demonstrating its excellent cycling performance and reversibility. It can be an alternative anode to other established electrode materials for real battery applications. [ABSTRACT FROM AUTHOR]

In order to investigate the enhancement of Zr in FTS performance, a series of Zr-modified 20 wt% Co/Al 2 O 3 catalysts has been prepared by regulating the Zr and Co impregnation order and Zr amount and then the catalytic performance were evaluated in a fixed reactor. The Zr addition leads to a significant increase in activity, olefin/paraffin ratio for C 3 and C 4 at a similar CO conversion, and selectivity to C 5 + compared with the Co/Al 2 O 3 catalysts. The co-impregnation of Zr and Co shows the most attractive catalytic performance. This can be attributed to the higher reducibility of the catalyst as well as the formation of Co–Zr interface. The introduction of Zr can enhance the interaction between C∗ and cobalt active sites and weaken the C O bond, making CO easier to be dissociated and the selectivity of C 5 + is improved. • The addition of Zr leads to a significant increase in activity, olefin/paraffin ratio for C 3 and C 4 at a similar CO conversion. • The introduction of Zr can promote the ability of CO dissociation and then improve the selectivity of C 5 +. • The improvement of Zr-modified Co/Al 2 O 3 catalytic performance is determined by the reducibility of the catalyst and the formed Co–Zr interface. [ABSTRACT FROM AUTHOR]

The low effectiveness factor of catalyst pellet caused by high internal diffusion limitation is a common issue in fixed‐bed reactor. Nevertheless, hierarchical structured catalyst provides a promising solution for the contradiction between reaction activity and diffusion efficiency in large catalyst pellets. Herein, we studied the effect of pore structure parameters of the meso‐macroporous catalyst on Fischer–Tropsch synthesis performances through experiment and pellet scale reaction–diffusion simulation. The pellet simulation firstly elucidated the reason for the significant improvement on activity and product selectivity for the meso‐macroporous catalyst observed in our experiment. Further optimization via pellet simulation indicated the critical influences of wax filling degree and that the perfect matching between reaction and mass transfer rates by increasing macropore size and adjusting porosity within pellet enables the C5+ space–time yield to the maximum. This work could provide a theoretical guideline for the engineering design of the hierarchical structured catalyst pellet. [ABSTRACT FROM AUTHOR]

Whether Co-ZrO 2 interfacial sites have a beneficial effect on Co-based Fischer-Tropsch synthesis is still controversial. In this paper, different quantities of Co-ZrO 2 interfacial sites were fabricated by changing the impregnation sequence of Zr added to Co/SiC catalysts. The effect of the Co-ZrO 2 interfacial sites was investigated by nitrogen adsorption, X-ray diffraction (XRD), hydrogen chemisorption (H 2 -TPD), temperature-programmed reduction (H 2 -TPR) and TEM-EDS- mapping analyses. It was found that when zirconium was on the surface of cobalt, more Co-ZrO 2 interfacial sites were formed, and a higher selectivity of long-chain hydrocarbons was observed. In addition, the formation of Co-ZrO 2 interfacial sites significantly increased the conversion frequency of CO. This work is of great significance for understanding the role of Co-ZrO 2 interfacial sites and guiding the design of related catalysts in Co-based Fischer-Tropsch synthesis. • Different content of Co-ZrO 2 interface active sites in Co/SiC catalysts were created. • Co/SiC catalysts with higher content of Co-ZrO 2 interfacial active sites have higher selectivity of long chain hydrocarbon. • This study provides support for the application of interface theory in catalysts in the future. [ABSTRACT FROM AUTHOR]

The modification of the equilibrium morphology to expose active facets of cobalt nanoparticles is essential for tailoring and controlling its catalytic performance. Periodic density functional theory (DFT) was applied to systematically investigate the structure and stability of exposed facets of hcp Co nanoparticles induced by Ru promoter in order to clarify the facet‐dependent equilibrium morphology of hcp Co nanoparticles stabilized by Ru promoter. The adsorption and migration of Ru atom can give rise to the change of the surface energy of exposed facets, thus affecting the equilibrium morphology of the hcp Co nanoparticles. Selectively exposed the high Miller index facets, such as Co(10‐12), Co(11‐20) and Co(11‐21) surfaces, can be tuned by adding Ru promoter. Our theoretical calculation results show that Co(11‐21) becomes the predominantly exposed facet accompanied with the decrease of exposed Co(10‐10) and Co(10‐11) with the increase of Ru loading. Further experimental studies suggest that the area of selectively exposed the Co(10‐11) surface for uniform Co nanoplates loaded with 3.0 wt % Ru will be reduced, which is in agreement with the theoretical predicted result. This work is helpful to design the desired Co‐based FTS catalysts rationally with well‐controlled surface structure. [ABSTRACT FROM AUTHOR]

[Display omitted] • A hierarchical micro-meso-macroporous Beta zeolite (HB) was developed by a steam-assisted crystallization method using meso-macroporous silica as the precursor and was employed for cobalt Fischer-Tropsch synthesis，exhibiting excellent catalytic performances. • The hierarchical micro-meso-macroporous Beta zeolite (HB) supported catalyst, on the one hand has a wealth of acidic sites, increasing the selectivity of isoparaffins; on the other hand has a good macroporous structure, which is favour for reducing the internal diffusion limitations, reducing the methane selectivity. • In this paper, we examined the effect of macroporoes on reducing internal diffusion limitations, confirming that macropores have good mass transfer and diffusion effects in large pellet catalysts. Large pellet catalysts were used in the evaluation process, which was very close to industrial production. A hierarchical micro-meso-macroporous Beta zeolite (HB) was developed by a steam-assisted crystallization method and was employed for cobalt Fischer-Tropsch synthesis. Meso-macroporous silica (HS), alumina modified meso-macroporous silica (HAS) and conventional Beta zeolite (CB) were used for comparison. Structural characterization indicated that the as-synthesized HB exhibited nanosized Beta zeolite crystallites and a hierarchical micro-meso-macroporous structure. The HB supported catalyst showed very high isoparaffins selectivity because of the isomerization reaction at the strong acidic sites of the Beta zeolite, while due to its good macroporous structure, which is in favor of reducing the internal diffusion limitations, the methane selectivity was kept as low as HAS supported catalysts. In this paper, we use large particle catalysts for evaluation, which are very close to industrial condition. And the conclusions obtained may be very important for the design of new Fischer-Tropsch catalysts. [ABSTRACT FROM AUTHOR]

In this work, the partial carbonization conversion of hcp-Co was carried out to obtain hcp-Co@Co 2 C compound with strong synergy, which exhibited high selectivity of higher alcohols owing to the obtained interface between hcp-Co and Co 2 C. [Display omitted] • The hcp-Co@Co 2 C catalyst was obtained by partial carbonization of hcp-Co. • There was a strong synergy between hcp-Co and Co 2 C due to the Co-Co 2 C interface. • Ethyne was used as a carbon source to dissociate on the surface of hcp-Co, and then Co was carbonized into Co 2 C. • The degree of carbonation conversion and synergy was easily controlled. • The hcp-Co@Co 2 C exhibited high selectivity of higher alcohols. The hcp-Co@Co 2 C catalysts were prepared by partial carbonization conversion of hcp-Co, which possessed rich Co-Co 2 C interface and strong synergy between hcp-Co and Co 2 C, compared with fcc-Co. The degree of carbonization conversion was easy to control, for ethyne was used as carbon source to dissociate on the surface of cobalt to form carbon species, and then carbonization conversion took place and hcp-Co@Co 2 C formed. The prepared hcp-Co@Co 2 C catalysts exhibited high selectivity of higher alcohols, compared with hcp-Co, owing to the rich interface and strong synergy between hcp-Co and Co 2 C. [ABSTRACT FROM AUTHOR]

Core-shell structure catalysts with adjustable carbon shell thickness and pore size were obtained by dissociating acetylene, leading to new product distribution characteristics: (1) the core–shell catalyst without reduction still showed high activity, and showed high selectivity of C 5 ∼C 12 (48.5%); (2) after reduction, it had the same activity as the uncoated catalyst, and showed high selectivity of C 13 ∼C 20 (41.7%), and high selectivity of C 5 ∼C 20 (66.9%); (3) more than 90% of the products are n-alkanes. [Display omitted] • Carbon coated catalysts were obtained at a low acetylene dissociation temperature. • The thickness of carbon coating can be regulated based on the dissociation temperature. • The carbon coating can determine the FTS products distribution. • More than 90% of the FTS products are n-alkanes. A series of carbon coated core–shell cobalt catalysts with different thickness of shell were easily prepared by C 2 H 2 dissociation. The characterization results showed that dissociation temperature plays an important role in determining the thickness of carbon shell. There were two kinds of carbon species on the surface of coated catalysts: deposited carbon and graphitic carbon. Only deposited carbon could be obtained during lower temperature coating, while both deposited carbon and graphitic carbon were found during higher temperature coating. Deposited carbon blocked the active sites, while graphitic carbon didn't block the active sites but only limited the diffusion of the products. The coated catalyst possessed better dispersion and reduction, and retains more elemental Co after surface passivation. The performance test results of Fischer-Tropsch synthesis (T = 220 °C) indicated that: (1) the core–shell catalyst without reduction still showed high activity, and showed high selectivity of C 5 ∼ C 12 (48.5%); (2) after reduction, it had the same activity as the uncoated catalyst, and showed high selectivity of C 13 ∼ C 20 (41.7%), and high selectivity of C 5 ∼ C 20 (66.9%); (3) more than 90% of the products were n-alkanes. [ABSTRACT FROM AUTHOR]

CeO 2 has obvious crystal selection effects on supported cobalt catalysts, the Co 3 O 4 supported on CeO 2 with nanorods, nanocubes, and nanopolyhedrons dominantly exposed (2 2 0), (1 1 1), and (3 1 1) planes, respectively, and the reduced Co dominantly exposed (10–11), (0001), and (1 1 1) planes, respectively, showing different catalytic performance for FTS. [Display omitted] • Supported Co 3 O 4 with exposing specific planes were obtained by varying CeO 2 planes. • Supported Co with exposing specific planes were obtained by varying CeO 2 planes. • Co(10–11) supported on rod CeO 2 exhibited the optimal catalytic performance for FTS. The exposing planes of carrier play an essential role in determining the exposing planes and catalytic performance of supported metal catalysts. In this work, Co 3 O 4 nanoparticles were supported on the CeO 2 nanorods, nanocubes, and nanopolyhedrons, with dominantly exposing CeO 2 (1 1 0), (1 0 0), and (1 1 1) planes, respectively. High resolution transmission electron microscope graphs clearly confirmed that CeO 2 has obvious crystal selection effects on supported cobalt, the corresponding supported Co 3 O 4 dominantly exposed (2 2 0), (1 1 1), and (3 1 1) planes, respectively, and the reduced Co dominantly exposed (10–11), (0001), and (1 1 1) planes, respectively. Their catalytic behaviors for Fischer–Tropsch synthesis (FTS) were studied in detail, and the optimal catalytic performance was obtained over the cobalt catalyst supported on CeO 2 nanorods, mainly due to its exposed Co (10–11) plane with low reaction barrier (-0.83 eV) after reduction. The laser Raman spectra, X-ray photoemission spectroscopy, temperature-programmed reduction, and in situ CO Fourier transform infrared spectroscopy further confirmed the effects of carriers with exposing different planes on the supported cobalt catalysts, explaining the reason for the significantly differences in FTS catalytic performance. [ABSTRACT FROM AUTHOR]

Nitrogen-doped ordered mesoporous carbons (OMCs) were prepared by using a post-synthetic method with cyanamide as a nitrogen source; they were used as supports for the fabrication of the cobalt-based Fischer-Tropsch synthesis (FTS) catalysts. The obtained composites were well characterised by using nitrogen physisorption, Raman spectroscopy, high-angle annular dark-field scanning transmission electron microscopy, hydrogen chemisorption, X-photoelectron spectroscopy, thermogravimetry-MS, and in situ XRD to investigate the effects of nitrogen on the dispersion of cobalt species and successive autoreduction behaviour of cobalt oxide as well as the catalytic performance in the FTS. The results indicate that the doped nitrogen atoms, especially the pyridine-like nitrogen, actually serve as the anchoring sites for cobalt species. Consequently, the more uniform cobalt particle size is observed for the catalysts with nitrogen-doped OMCs as supports in comparison with their counterparts based on the pristine OMCs. In contrast, the autoreduction temperature of cobalt oxide in the as-synthesised catalysts lowers considerably after nitrogen doping, although slightly increased autoreduction temperature is observed for the catalysts with relatively high nitrogen content owing to the metal-support interaction. Dictated by the balance between decreasing particle size of cobalt and increasing strength of the metal-support interaction, the cobalt specific activity of the nitrogen-doped catalysts reaches a maximum and then decreases in the FTS with increasing nitrogen content. Notably, under optimum conditions, the cobalt specific activity on the nitrogen-doped sample with medium nitrogen content is 1.5 times higher than its analogue on the pristine OMC without compromising the selectivity to C5+ hydrocarbons. [ABSTRACT FROM AUTHOR]

A series of core-shell-structured catalysts that consist of different-sized Co3O4 nano-particles and silica shells were prepared by an in situ coating method. The reduced catalysts displayed uniform core sizes that ranged from 5.5-12.7 nm as ascertained by TEM, which concurred well with XRD analysis. The BET results revealed the highly mesoporous nature of the silica shell, which contributes to the facile access of the reactant gas to the active sites on the core particles. The degree of reduction of the calcined catalysts studied by H2 temperature-programmed reduction was enhanced with increased Co particle size. In the Fischer-Tropsch synthesis, a volcano-like curve was plotted as the CO conversion and Co-time-yield revealed a rapid growth if the particle size increased from 5.5 to 8.7 nm and then decreased with further increased particle size to 12.7 nm, which is an effect of the combination of Co dispersion and reducibility. However, the turnover frequency remained invariant for catalysts with particle sizes larger than 8.7 nm. If we consider the product selectivity, generally, larger particles led to a longer chain length of hydrocarbons with a larger chain-growth probability. The selectivity towards methane decreased and the corresponding heavy hydrocarbons (C19+) increased continuously with the increase of particle size. The catalyst with a particle size of 8.7 nm exhibited the highest selectivity and the maximum space-time-yield towards middle distillates (C5-C18) because of the modest chain-growth probability. [ABSTRACT FROM AUTHOR]

Highlights: [•] In situ coating method is developed to prepare silica coated core–shell catalysts. [•] An uncoated catalyst with cobalt particles outside silica beads is also obtained. [•] Silica coating leads to diffusion restrictions of reactants, which lowered molecular weight of hydrocarbon products. [•] Silica coating increases product selectivity toward middle distillates and olefins. [ABSTRACT FROM AUTHOR]

Abstract: Different CoZr/H-ZSM-5 hybrid catalysts were prepared by a hydrothermal synthesis method, where H-ZSM-5 was enwrapped onto the Co-ZrO2 Fischer–Tropsch synthesis (FTS) catalyst. The catalysts were characterized by BET, XRD, 27Al NMR, SEM, TEM, XPS, H2-TPR, NH3-TPD and IR techniques. The catalytic performance for the direct conversion of syngas to high-octane gasoline-range (C5–11) hydrocarbons was studied. Coke formation on the spent catalysts was measured by TGA. Compared with the base Co-ZrO2 catalyst or the physically mixed catalyst of Co-ZrO2 with H-ZSM-5, the reducibility of the hybrid catalyst was much lower due to the strong interactions of cobalt phase with zeolite and/or zirconia. The catalytic performance results showed that the as-prepared hybrid catalysts had high selectivity towards gasoline-range isoparaffins and relatively low methane selectivity in spite of the relatively low catalytic activity. The hybrid catalysts could effectively minimize the accumulation of carbonaceous deposits. The catalyst with aluminum isopropoxide as Al source exhibited excellent selectivity on the isoparaffin synthesis and relatively good stability. [Copyright &y& Elsevier]

Modified alumina carriers were obtained by pre-coating cobalt aluminate on the surface of common alumina. Next, supported cobalt catalysts were obtained by incipient wetness impregnation, and their FTS performances were evaluated in a fixed-bed reactor. In situ XRD results suggested that HCP Co was obtained after reducing the aluminate-modified alumina-supported cobalt catalysts, as opposed to FCC Co, which was supported on common alumina. H 2 -TPR results demonstrated that the modified catalysts possessed lower reduction temperatures. CO-TPD and in situ CO-FTIR characterizations indicated that bridged rather than linear CO adsorption occurred on the modified catalysts. The evaluation results indicated that the aluminate-modified catalysts possessed higher CO conversion rates, higher C 5 + selectivity, higher cobalt specific activity, higher C 5 + space-time yields (STYs), and lower methane selectivity than conventional catalysts in the FTS process. [ABSTRACT FROM AUTHOR]

Abstract: Silylated Co3O4-mesoporous SiO2 catalysts were prepared by a surface organic modification to understand the influence of a hydrophobic surface on their performance in the Fischer–Tropsch synthesis (FTS). Fourier transform infra-red (FT-IR) spectra showed that the reaction of the surface silanol groups with hexamethyldisilazane (HMDS) took place effectively, and X-ray diffraction (XRD) indicated that such a modification did not affect Co3O4 crystallite size. Furthermore, hydrogen temperature programmed reduction (H2-TPR) illustrated a higher extent of reduction for silylated Co3O4-m-SiO2 catalysts. As a result, such a silylated core–shell structured Co catalyst showed the higher catalytic activity and better selectivity towards C5–C18 fraction than the unsilylated Co3O4-m-SiO2 catalyst in the FTS, which was likely favorable to the internal transportation and their hydrophobic shell. [Copyright &y& Elsevier]

Abstract: Monodispersible Co3O4 nanoparticles were prepared via a facile solvothermal route using polyvinylpyrrolidone (PVP) as the capping agent. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) results, together with the N2 physisorption, indicated that those as-made Co3O4 nanoparticles of about 17nm could be used as cores to prepare core@shell nanocomposites with mesoporous silica shell. Such monodispersible Co3O4 nanoparticles were observed to be coated completely by mesoporous silica shell, and showed the higher catalytic activity and selectivity towards C5–C18 fraction than Co/mesoporous SiO2 (Co/m-SiO2) in the Fischer–Tropsch synthesis (FTS). [ABSTRACT FROM AUTHOR]

In the present work, CoZr catalysts without support have been prepared to investigate the nature of the Zr promotion. Evidences from multiple techniques shows that Zr prefers to locate on the coordinately unsaturated sites of nano-Co 3 O 4 , then enters the lattice of Co metal after reduction, leading to the lattice expansion. Benefitting from Zr induced structural changes of the Co metal, CO adsorption and dissociation have been enhanced. Besides, due to the strong interaction between Co and Zr, the growth of the Co metal crystal size during reduction and O atoms adsorption on the reduced catalysts surface are inhibited obviously, which makes more Co atoms available during FTS reaction. As a result, the catalytic performances are improved significantly. [Display omitted] • CoZr catalysts without support have been prepared under a wide range of Zr/Co molar ratio. • Zr prefers to locate on the coordinately unsaturated sites of nano-Co 3 O 4 , then enters the lattice of Co metal after reduction, leading to the lattice expansion. • The growth of the Co metal crystal and O atoms adsorption on the reduced catalysts surface are inhibited significantly. • The CoZr catalysts exhibits high activity and C 5 + selectivity. It is reported that Zirconium (Zr) is an effective promoter of cobalt-based catalysts for Fisher-Tropsch synthesis (FTS). Numerous studies have been conducted to explore the nature of the promotion. However, many of these studies focus on oxide-supported cobalt-based catalysts, in which the support effects may have partially enhanced or masked the influences of Zr. In the present work, CoZr catalysts without oxide support have been prepared across a wide range of Zr/Co molar ratio from 0.04 to 0.33 to investigate the nature of the Zr promotion. Comparing with the nano-Co 3 O 4 , the promoted catalysts exhibit excellent performance. The reaction temperature required to convert the same amount of syngas on the same amount of cobalt has decreased by about 40 °C. The selectivity of C 5 + has increased from 70∼81% to over 85% at the same CO conversion, and even higher than 90% on the CoZr catalysts with high Zr/Co ratio. Evidences from multiple techniques, including in situ XPS, CO-DRIFTs, CO-TPD, NH 3 -TPD, Py-IR, HRTEM, Raman and XRD, shows that Zr tends to occupy the coordinately unsaturated sites of nano-Co 3 O 4. After reduction, Zr enters the lattice of Co metal, leading to the lattice expansion. Benefitting from the Zr induced structural changes of the Co metal, CO adsorption and dissociation on the CoZr catalysts have been enhanced. Besides, due to the strong interaction between Co and Zr, the growth of the Co metal crystal during H 2 reduction and O atoms adsorption on the reduced catalysts surface are inhibited significantly, which make more Co atoms available during FTS reaction. As a result, the catalytic performances are improved obviously. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The content of SiO x C y on SiC surface decreased after nitric acid treatment. • SiO x C y had great effect on the electron density and reduction degree of cobalt species. • The decrease of SiO x C y on SiC surface allowed a significant improvement of the C 5+ selectivity of Co/SiC catalysts. Abstract Co/SiC catalysts were prepared to investigate the role of SiO x C y on SiC surface in the catalytic performance for Fischer–Tropsch synthesis. SiC was pretreated by nitric acid with different concentration, and the Co/SiC catalysts were prepared and characterized by N 2 -adsorption, H 2 -chemisorption, XRD, TPR, TPO, XPS, and TEM. It was found that the decrease of SiO x C y caused by nitric acid treatment may be related to the increase of reducibility of Co/SiC catalysts and the decrease of binding energy of cobalt. The catalytic performance revealed that the less the content of SiO x C y was, the higher the selectivity of long chain hydrocarbon was. It was concluded that the strong electronegativity of SiO x C y had great effect on the electron density of cobalt species and then on the catalytic performance of the Co/SiC catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three single types of deposited carbon (atomic carbon, polymeric carbon and graphitic carbon) on Co-based catalyst are successfully constructed. • The Co catalyst with atomic carbon exhibits very high Fischer-Tropsch activity and low methane selectivity. • Polymeric carbon and graphitic carbon are detrimental to the Fischer-Tropsch reaction performance. There is less agreement on the role of carbon deposits during FT reaction. Identifying and characterizing carbon species of cobalt catalyst is highly challenging for the Fischer-Tropsch Synthesis (FTS). Here, a serial of predeposited composite carbon and single carbon are constructed, and their roles in F-T synthesis are investigated on metal cobalt catalyst excluding the texture influence of the promoter and the support. Different carbon deposits are introduced on cobalt-based catalysts under different carbon-containing reducing atmospheres utilizing the pretreatment method. Atomic carbon, polymeric carbon, graphitic carbon, and combinations of them were distinguished by the characterization techniques of TPH, Raman and XPS. A significant difference occurred in both the catalytic activity and selectivity to methane after predeposited carbon on the Co-based catalysts. The p-Co-5 % syn -3 g-24 h-250-RO catalyst with single atomic carbon shows a remarkably low methane selectivity (4.03 %), high C 5+ selectivity (76.38 %), and more importantly, excellent stability (TOS = 144 h) in FTS. Moreover, all of the Co-based catalysts containing the predeposited carbon can be directly used in the FT reaction without reduction procedure. [ABSTRACT FROM AUTHOR]

High thermal conductive Al 2 O 3 @Al composite synthesized via metallic Al powders corrosion method has been applied as support for preparing Co/Al 2 O 3 @Al catalyst for high exothermic Fischer-Tropsch synthesis. The prepared Al 2 O 3 @Al composite is a hierarchical macro-mesoporous structure and consist of two parts, namely the inner metallic Al and the outer Al 2 O 3 with two kinds of morphologies. Increasing the concentration of the corrosive NaOH or extending the corrosion time could increase the specific surface area of the composite. For the prepared Co/Al 2 O 3 @Al, Co 3 O 4 phase is located on the outer plate-like Al 2 O 3 layer. The Co/Al-0.03-20 possesses higher CO conversion and C 5+ selectivity due to the appropriate cobalt reducibility, dispersion and high thermal conductivity. The thermal conductive coefficient of Co/Al 2 O 3 @Al catalysts is 13–98 times of conventional Co/Al 2 O 3 . Compared to Co/Al 2 O 3 , the Co/Al 2 O 3 @Al shows higher CO conversion and C 5+ selectivity as well as lower CH 4 and CO 2 selectivity, which is attributed to the macro-mesoporous structure and high thermal conductivity. In addition, because of the high thermal conductivity, no heat disperser should be used and a homogeneous temperature gradient maintains within the catalyst bed for Co/Al 2 O 3 @Al. [ABSTRACT FROM AUTHOR]

• Structured cobalt-based catalysts for FTS are reviewed. • Carbon and silicon carbide supported cobalt catalysts for FTS are reviewed. • The Al 2 O 3 @Al supported cobalt catalysts for FTS are introduced. • The industrial application of the Co/Al@Al 2 O 3 is prospected. The fixed-bed reactor is a good choice for the cobalt-based Fischer-Tropsch synthesis (FTS) to produce hydrocarbons. However, the heat transfer limitation of the fixed-bed reactor greatly threatens the safe operation of the reactor and modifies the overall products selectivity on account of the strong exothermic property of FTS. Therefore, it is urgent to strengthen the heat transfer for FTS in the fixed-bed reactor. In this review, the utilizations of the structured catalysts as well as the high thermal conductive carbon and silicon carbide supported cobalt catalysts to improve the heat transfer for FTS are summarized. More importantly, the research progress on the utilization of the novel, high thermal conductive Al 2 O 3 @Al as support for the cobalt-based FTS is emphatically introduced. It demonstrates that the heat transfer efficiency value k eff of the reactor bed packed with the Co/Al 2 O 3 @Al catalysts is 2–3 times higher than that of the conventional Co/Al 2 O 3. As a consequence, the heavy hydrocarbon selectivity is significantly increased for Co/Al 2 O 3 @Al, which makes it very promising for industrial application. The possible technical problems in large-scale industrial applications and their solutions over the Co/Al 2 O 3 @Al are also prospected in this review. [ABSTRACT FROM AUTHOR]

Abstract: A series of silylated Co/SBA-15 catalysts were prepared via the reaction of surface Si–OH of SBA-15 with hexamethyldisilazane (HMDS) under anhydrous, vapor-phase conditions, and then characterized by FT-IR, N2 physisorption, TG, XRD, and TPR-MS. The results showed that organic modification led to a silylated SBA-15 surface composed of stable hydrophobic Si–(CH3)3 species even after calcinations and H2 reduction at 673K. Furthermore, the hydrophobic surface strongly influenced both metal dispersion and reducibility. Compared with non-silylated Co/SBA, Co/S-SBA (impregnation after silylation) showed a high activity, due to the better cobalt reducibility on the hydrophobic support. However, S-Co/SBA (silylation after impregnation) had the lowest FT activity among all the catalysts, due to the lower cobalt reducibility along with the steric hindrance of grafted –Si(CH3)3 for the re-adsorption of α-olefins. [Copyright &y& Elsevier]

[Display omitted] • The synergistic effect between Ba and Ru was reported at the first time. • An improved CO conversion and excellent selectivity to high C 5 + selectivity was obtained. • The introduction of Ba induced both site poisoning and electronic effects. • The synergistic effect between Ba and Ru was responsible for the enhanced CO dissociation ability. • Other alkali earth metal promoters had a similar influence on the Co-0.1Ru/Al 2 O 3 catalysts for the FTS reaction. Alkali earth metals and Ru are famous selectivity promoters in cobalt-based Fischer-Tropsch synthesis. Ba has displayed as an effective selectivity promoter, however, the presence of Ba leads to a dropped CO conversion yield. To combine the advantages of Ba and Ru in promoting selectivity, Ba-modified alumina was fabricated and used as the supports for Co and Co-Ru catalysts. Promotion of Co/Al 2 O 3 by a combination of Ru and Ba achieved an increase of CO conversion and a low CH 4 selectivity due to the enhanced CO dissociation than unmodified and a single additive modified catalyst. The influences of other alkali earth metal additives were also investigated, which had a similar impact that of Ba on the Co-Ru catalysts for promoting FTS reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Model FTS catalyst granules with different thermal conductivity were prepared. • Overheating effect was exist within catalyst granule with low thermal conductivity. • Thermal conductivity of FTS catalyst granules could influent the catalytic performance. • Thermal conductivity could affect syngas adsorption, hydrogenation and chain growth. A series of model Fischer-Tropsch synthesis (FTS) catalyst granules with different thermal conductivity were prepared to study the influence of catalyst granule thermal conductivity on FTS performance. A clear correlation was found between catalyst granule thermal conductivity and FTS activity, CH 4 selectivity, C 5+ selectivity, mole ratio of olefin to paraffin and branched hydrocarbon selectivity at high CO conversion. This could be due to that the overheating effect occurred within catalyst granule with low thermal conductivity. On the basis of the widely accepted 'alkyl' mechanism for FTS, the overheating effect was able to affect the adsorption of H 2 and CO molecules, the hydrogenation of carbide species as well as chain growth. In addition, the overheating effect could lead to the catalyst structure reconstruction, sintering and deactivation. [ABSTRACT FROM AUTHOR]