FT Catalysts Research Articles

Fischer-Tropsch synthesis: Platinum promoted Co@HCS catalysts

Hollow carbon sphere (HCS) nanoreactors were used as a catalyst support for Co, with Pt as a promoter. The hollow morphology of the HCSs nanoreactor was exploited to study the influence of the Pt promoter nanoparticle location relative to that of the Co3O4 (Co 10 wt%) nanoparticles (dCo = 3.5 – 12.5). Furthermore, the effect of Pt on the reduction behaviour and activity of the Co FTS catalyst was evaluated. The synthesis and use of Pt nanoparticles supported on/in Co@HCS FT catalysts to give CoPt@HCS and Pt/(Co@HCS) catalysts are reported. Electron microscopy, ex situ PXRD, BET, and TPR studies revealed that the prepared catalysts were successfully synthesized with well dispersed Co nanoparticles. It was observed that the proximity between the Co and Pt influenced the Co hcp/fcc ratios. A secondary hydrogen spillover effect was invoked to account for the reduction of Co3O4 on 1Pt/(10Co@HCS) at 335 °C. The complete reduction of Co3O4 to Co metal on 10Co1Pt@HCS at 350 °C was attributed to a primary hydrogen spillover effect. Following catalyst activation at 350 °C, the primary spillover process resulted in a catalyst exhibiting higher Fischer–Tropsch activity (approximately 2×) compared to both the unpromoted catalyst and catalysts where Pt and Co were separated by the HCS. This enhanced activity was partially attributed to the Co phases formed on the carbon support during reduction and the degree of catalyst reduction, which depended on the type of hydrogen spillover process. A comparison of the reduction ability of Os, Ru and Pt on the reduction of Co supported on/in HCSs and the impact of the promoter on Co hcp/fcc ratios is reported.

Fischer-Tropsch synthesis: Osmium promoted Co@HCS catalysts

Little attention has been given to the use of osmium as a promoter for Fischer-Tropsch Synthesis (FTS). In previous studies, Os has proven to be a poor FT catalyst, but its use as a catalyst promoter has not been studied. In this study, the synthesis and use of Os nanoparticles supported on/in Co@HCS (HCS = hollow carbon sphere) FT catalysts are reported. The hollow morphology of the HCSs was exploited to study the influence of Os promoter nanoparticle location relative to the Co3O4 nanoparticles (dCo = 3.5–12.5 nm) and on the effect of Os on the reduction behaviour and activity of the Co FT catalyst. Os (0.1, 0.5 and 1 wt%) nanoparticles were loaded both inside and outside the HCSs, while the Co3O4 particles (Co 10 wt%) were loaded inside of the HCSs to give CoOs@HCS and Os/(Co@HCS). Electron microscopy, in situ PXRD, PDF, TGA, BET, and TPR studies revealed that both catalysts were successfully synthesized. The use of ex-situ PXRD, PDF and TPR studies provided information on the Co phases and reduction pathways of the Co3O4 metal catalyst and the spillover effect from Os to Co. Co3O4 and CoO phases were observed for the CoOs@HCS and Os/(Co@HCS) catalysts. More interesting was the observation of the Co fcc phase in the OsCo@HCS catalysts, indicating the importance of the Os-Co interaction. The catalyst with Co and Os close together (primary spillover process) gave a higher Fischer-Tropsch activity (38.5–46.4 × 10−6 molCO/gCo.s) and higher C5+ production than both the unpromoted catalyst (27.8 × 10−6 molCO/gCo.s), and the catalysts where Os and Co were separated (25.1–36.4 × 10−6 molCO/gCo.s) by the mesoporous carbon shell (secondary spillover effect). The studies on both CoOs@HCS and Co/(Os@HCS) catalysts have indicated for the first time the effect of Os on Co catalysts, with particular reference to FTS.

MOF-Derived Porous Carbon-Supported Bimetallic Fischer–Tropsch Synthesis Catalysts

Generally, incorporating different metals in a catalyst can provide a synergistic effect for enhancing the catalytic performance. However, the interaction between the two metals and the effect on the catalytic performance seem elusive. In this work, a bimetallic metal–organic framework (MOF) is synthesized, and then, a novel bimetallic catalyst is prepared for Fischer–Tropsch synthesis (FTS). The combination of these different metals and a MOF-derived porous carbon supporter offers a unique active surface structure that may lead to improved catalytic performance. Herein, alloy-type structures were observed in FeCo and FeNi bimetallic MOF-derived catalysts, while a solid solution with a spinel structure were observed in FeMn and FeZn bimetallic MOF-derived catalysts. The bimetallic catalysts supported on MOF-derived porous carbon display stable and excellent catalytic performance during 100 h compared with a single-metal Fe catalyst. X-ray diffraction measurement, X-ray photoelectron spectroscopy, and H2 temperature-programed reduction were employed to study the synergistic effect of bimetallic components on surface composition and electronic and reduction properties accordingly. The relationship between catalytic performance and catalyst composition was deeply studied. These research work results will provide a new approach to design novel bimetallic FT catalysts.

Fischer–Tropsch Synthesis for Light Olefins from Syngas: A Review of Catalyst Development

Light olefins as one the most important building blocks in chemical industry can be produced via Fischer–Tropsch synthesis (FTS) from syngas. FT synthesis conducted at high temperature would lead to light paraffins, carbon dioxide, methane, and C5+ longer chain hydrocarbons. The present work focuses on providing a critical review on the light olefin production using Fischer–Tropsch synthesis. The effects of metals, promoters and supports as the most influential parameters on the catalytic performance of catalysts are discussed meticulously. Fe and Co as the main active metals in FT catalysts are investigated in terms of pore size, crystal size, and crystal phase for obtaining desirable light olefin selectivity. Larger pore size of Fe-based catalysts is suggested to increase olefin selectivity via suppressing 1-olefin readsorption and secondary reactions. Iron carbide as the most probable phase of Fe-based catalysts is proposed for light olefin generation via FTS. Smaller crystal size of Co active metal leads to higher olefin selectivity. Hexagonal close-packed (HCP) structure of Co has higher FTS activity than face-centered cubic (FCC) structure. Transition from Co to Co3C is mainly proposed for formation of light olefins over Co-based catalysts. Moreover, various catalysts’ deactivation routes are reviewed. Additionally, techno-economic assessment of FTS plants in terms of different costs including capital expenditure and minimum fuel selling price are presented based on the most recent literature. Finally, the potential for global environmental impacts associated with FTS plants including atmospheric and toxicological impacts is considered via lifecycle assessment (LCA).

In Situ Active Site for CO Activation in Fe-Catalyzed Fischer-Tropsch Synthesis from Machine Learning.

In situ-formed iron carbides (FeCx) are the key components responsible for Fischer-Tropsch synthesis (FTS, CO + H2 → long-chain hydrocarbons) on Fe-based catalysts in industry. The true active site is, however, highly controversial despite more than a century of study, which is largely due to the combined complexity in both FeCx structures and mechanism of CO hydrogenation. Herein powered by machine learning simulation, millions of structure candidates for FeCx bulk and surfaces are explored under FTS conditions, which leads to resolving the active site for CO activation. This is achieved without a priori input from experiment by first constructing the thermodynamics convex hull of bulk phases, followed by identifying the low surface energy surfaces and evaluating the adsorption ability of CO and H, and finally determining the lowest energy reaction pathway of CO activation. Rich information on FeCx structures and CO hydrogenation pathways is gleaned: (i) Fe5C2, Fe7C3, and Fe2C are the three stable bulk phases under FTS in producing olefins, where Fe7C3 and Fe2C have multiple energetically nearly degenerate bulk crystal phases; (ii) only three low surface energy surfaces of these bulk phases, namely, χ-Fe5C2(510), χ-Fe5C2(111), and η-Fe2C(111), expose the Fe sites that can adsorb H atoms exothermically, where the surface Fe:C ratio is 2, 1.75, and 2, respectively; (iii) CO activation via direct dissociation can occur at the surface C vacancies (e.g., with a barrier of 1.1 eV) that are created dynamically via hydrogenation. These atomic-level understandings facilitate the building of the structure-activity correlation and designing better FT catalysts.

Fischer–Tropsch Synthesis: Study of Different Carbon Materials as Cobalt Catalyst Support

In this work, cobalt Fischer–Tropsch synthesis (FTS) catalyst supported on various carbon materials, i.e., carbon nanotube (CNT), activated carbon (AC), graphene oxide (GO), reduced graphene oxide (rGO), and carbon nanofiber (CNF), were prepared via impregnation method. Based on TGA, nitrogen physisorption, XRD, Raman spectroscopy, H2-TPR, NH3-TPD, ICP, SEM, and TEM characterization, it is confirmed that Co3O4 particles are dispersed uniformly on the supports of carbon nanotube, activated carbon and carbon nanofiber. Furthermore, the FT catalyst performance for as-prepared catalysts was evaluated in a fixed-bed reactor under the condition of H2:CO = 2:1, 5 SL·h−1·g−1, 2.5 MPa, and 210 °C. Interestingly, the defined three types of carbon materials exhibit superior performance and dispersion compared with graphene oxide and reduced graphene oxide. The thermal stability and pore structure of the five carbon materials vary markedly, and H2-TPR result shows that the metal–support interaction is in the order of Co/GO > Co/CNT > Co/AC > Co/CNF > Co/rGO. In brief, the carbon nanofiber-supported cobalt catalyst showed the best dispersion, the highest CO conversion, and the lowest gas product but the highest heavy hydrocarbons (C5+) selectivity, which can be attributed to the intrinsic property of CNF material that can affect the catalytic performance in a complicated way. This work will open up a new gateway for cobalt support catalysts on various carbon-based materials for Fischer–Tropsch Synthesis.

Relay catalysis in the conversion of syngas

China’s energy resource structure is rich in coal but poor in crude oil. For a long time, China has to rely on importing crude oil to meet the domestic demand for liquid fuels (including gasoline, aviation fuel and diesel fuel) and basic chemicals (such as C2–C4 lower olefins, aromatics, and C2+ oxygenates). In 2019, China’s dependence on oil imports has exceeded 70%, which has a negative impact on the social-economic development and national security. Thus, it is very urgent and important to produce liquid fuels and bulk chemicals based on coal resource. Syngas (a mixture of CO and H2) can be largely produced from the non-oil resources, such as coal, gas (natural gas, shale gas, and coal-bed methane), and biomass. From syngas, various hydrocarbon products can be produced as supplement of oil-derived products. The conversion of syngas to target products with high selectivity is the core of C1 chemistry. However, by the classical Fischer-Tropsch synthesis (FTS) route, the product selectivity is limited by the Anderson-Schulz-Flory (ASF) distribution, which results in the low selectivity of target products. In practice, the yields of liquid fuels and bulk chemicals are increased by a secondary process such as (hydro)cracking, isomerization and aromatization. The direct conversion of syngas to target products with high selectivity is attractive but challenging. Recently, the concept of relay catalysis has been successfully applied to the one-step transformation of syngas to liquid fuels and bulk chemicals with ultrahigh selectivity over bifunctional or multifunctional catalysts. The selectivity of target hydrocarbon products can break the limitation of the ASF distribution. In the conversion of syngas to liquid fuels, the used bifunctional catalysts are composed of FT catalysts and zeolites. FT catalysts, such as Fe (Fe x C y ), Co and Ru, are responsible for the activation of CO and the growth of carbon chain. Zeolites are in charge of the hydrocracking and isomerization. High selectivity of middle-distillates, such as gasoline (C5–C11 hydrocarbons), jet fuel (C8–C16 hydrocarbons) and diesel fuel (C10–C20 hydrocarbons), have been obtained via relay catalysis. It was found that the catalytic performances were strongly influenced by the topology, acidity and mesoporosity of zeolites as well as the metal sizes and promoters. The importance of hydrocracking on acid sites and hydrogenolysis on the metal nanoparticles for the selective C–C cleavage has also been analyzed. The selective synthesis of basic chemicals can also be achieved by relay catalysis, where the bifunctional catalysts consist of metal oxides (such as the solution solid ZnO-ZrO2, and the spinel structure of ZnCr2O4, ZnAl2O4) and zeolites (such as SAPO-34, ZSM-5, MOR). The activation of CO to intermediates (CH3OH/DME or ketene) proceeds on the metal oxides and the selective C–C bond formation proceeds on the zeolites. The reaction mechanism of such kind of bifunctional catalysts differs from that of the conventional FT catalysts, where the CO activation and C–C coupling are conducted over different sites. The selectivity of lower olefins and aromatics could reach up to 85% without the formation of undesired methane. Besides, multifunctional catalysts can offer an 80% selectivity towards C2+ oxygenates such as methyl acetate, acetic acid, and ethanol by coupling CO activation and carbonylation. The product selectivity of oxygenates was significantly impacted by the zeolite acidity and the proximity between the two functional components. The present review not only summarizes the major advantages and disadvantages of the relay catalysis in syngas conversion but also offers prospects for future development of relay catalysis in syngas conversion.

Optimizing preparations of Co Fischer-Tropsch catalysts for stability against sintering

Catalyst deactivation is of a major concern in industrial applications. Catalyst deactivation in any process can be minimized through: (i) appropriate catalyst design, and (ii) careful process control. In the present review we focus on the design of a Co catalyst to significantly hinder catalyst deactivation via sintering during FT reaction while enhancing catalytic activity and selectivity. First, it is shown how support and promoter physical and chemical properties can affect Co catalyst design. Support physical and chemical properties essential for preparing an optimally active, selective, and stable, commercial Co FT catalysts are recommended. Secondly, it is explained how carefully-controlled deposition of a Co salt via industrially-realistic methods is critical in controlling catalyst precursor-support interactions, nanocrystal size, and spatial distributions vital to sintering resistance. Three catalyst precursor deposition methods are discussed: impregnation, precipitation, and solution combustion; advantages and disadvantages of each method are detailed. Finally, effects of drying, calcination, and reduction on catalyst properties important to activity, selectivity and resistance to sintering are explained, and best practices for conducting each step are recommended.

Phase transfer catalyst-assisted reversed-phase dispersive liquid–liquid microextraction for the rapid determination of organic acids in Fischer-Tropsch oil products

A method prior to using high-performance liquid chromatography (HPLC), named phase transfer catalyst-assisted reversed-phase dispersive liquid–liquid microextraction (PTC-RP-DLLME), was developed for the rapid determination of organic acids in Fischer-Tropsch synthesis (FTS) oil products. This method used sodium hydroxide solution and tetrabutylammonium bromide (TBAB) as an extractant and a disperser respectively, in which the TBAB promoted the dispersion of aqueous NaOH solutions in the organic product, and acted as a hydrogen bond receptor to enhance the extraction of organic acids via hydrogen bond interactions. Under the optimized conditions, the calibration curves in the range of 0.1–30 μg mL−1 showed correlation coefficients (r) of 0.998–0.999. Detection limits (S/N = 3) were ranged from 1.0 to 3.5 ng mL−1. The relative standard deviations of intra-day and inter-day repeatability were in the range of 2.9–5.8 % and 4.1–6.7%, respectively. The recoveries ranged from 85.4% to 105.9%. This developed method was employed for the analysis of organic acids in 6 types of oil products. This work provides an efficient and rapid pretreatment method for acid concentration prior to HPLC, and therefore saves time and cost for the quantitative analysis of FTS oil products. Moreover, precise analysis by application of this method is fairly beneficial to the FT catalyst improvement and industrial equipment material selection, and is rather significant for the proper design of the downstream processing/purification system.

Production of CO2-neutral liquid fuels by integrating Fischer-Tropsch synthesis and hydrocracking in a single micro-structured reactor: Performance evaluation of different configurations by factorial design experiments

Abstract Humankind must drastically reduce CO2 emissions within the next three decades to limit global climate change. Defossilization of the transport sector must contribute to the achievement of this ambitious aim. One promising option is the production of synthetic liquid fuels from CO2, water, and renewable electrical energy. Liquid fuels will also be used in the future, especially for heavy-duty vehicles and aviation. We studied the production of liquid fuels by integration of Fischer-Tropsch Synthesis (FTS) and Hydrocracking (HC) in a single micro-structured reactor. Thereby, we addressed the aspects of process simplification and process intensification. Both are particularly important for flexible small-scale plants for decentralized application in context of the energy transition. In this study, we systematically investigated the performance of the integrated FTS/HC process depending on different operating conditions (pressure, temperature, weight hourly space velocity, H2/CO synthesis gas ratio) and integration configurations by applying a factorial design approach. Beyond the selectivity of the process towards liquid fuels, we especially focus on the product quality affected by the type of produced hydrocarbons. We identified significant influence parameters on process performance, which is essential to know for practical application. We showed that the crude product quality was significantly influenced by the integration pattern. Therefore, we suggested more elaborate integration configurations to overcome the challenge of suboptimal operation conditions for the FT and HC catalyst and improve the product quality.

Exploring the Reaction Paths in the Consecutive Fe-Based FT Catalyst–Zeolite Process for Syngas Conversion

Direct conversion of syngas into aromatics with tandem catalysts containing Fe-based Fischer–Tropsch synthesis (FTS) catalysts and zeolites has been attracting significant attention because of the ...

Accumulation of liquid hydrocarbons during cobalt-catalyzed Fischer–Tropsch synthesis - influence of activity and chain growth probability

It may take over one year in order to fill FT catalyst pores, depending on activity and chain growth probability.

Effect of reduction on Co catalyst active phase highlighted by an original approach coupling ASAXS and electron tomography

Diversification of liquid fuel sources for transportation plays a key role in the energetic transition. High quality and clean diesels can be produced by Fischer-Tropsch synthesis, which interest is renewed in as much it can be performed from syngas (CO + H2) produced by conversion of natural gas or gasification of lignocellulosic biomass, leading, in this latter case, to fuels from renewable resource. Catalytic performance (activity and selectivity) of cobalt-based catalysts are related to the physico-chemical characteristics of the cobalt nanoparticles. The present study proposes a new approach to obtain a detailed and exhaustive description of the cobalt active phase in FT catalysts. We combined Anomalous Small X ray Scattering (ASAXS) and electron tomography, giving complementary insights on the microstructure and size distribution of both cobalt nanoparticles and aggregates. This approach, carried out on a cobalt/alumina-silica catalysts studied first at the oxide state and then at the reduced state, allowed to highlight the mechanisms involved at the nanoscale during the reduction step. Reduction impact is significant on aggregates morphology, causing their fragmentation and increasing their accessibility. As a perspective, a better knowledge of cobalt aggregates morphology will help to understand their impact on the catalyst performance.

Insight into CH4 formation and chain growth mechanism of Fischer−Tropsch synthesis on θ-Fe3C(0 3 1)

θ-Fe3C has been reported to play a key role in C2−C4 olefins production for Fischer−Tropsch synthesis. In this work, (031) is confirmed as the most exposed facet of θ-Fe3C due to its thermodynamic stability. Investigation on CH4 formation and C1−C1 coupling reveals that CH4 formation exhibits a high effective barrier and CH+CH and CH2+CH2 are the dominant chain growth pathways. ΔEeff was employed to quantify the selectivity of CH4 and C2+. The high value of ΔEeff indicates the preference of C2+ formation to CH4. These results will help for the design of selective Fe-based FT catalysts.

Metal-support interaction on cobalt based FT catalysts - a DFT study of model inverse catalysts.

It is challenging to isolate the effect of metal-support interactions on catalyst reaction performance. In order to overcome this problem, inverse catalysts can be prepared in the laboratory and characterized and tested at relevant conditions. Inverse catalysts are catalysts where the precursor to the catalytically active phase is bonded to a support-like ligand. We can then view the metal-support interaction as a ligand interaction with the support acting as a supra-molecular ligand. Importantly, laboratory studies have shown that these ligands are still present after reduction of the catalyst. By varying the quantity of these ligands present on the surface, insight into the positive effect SMSI have during a reaction is gained. Here, we present a theoretical study of mono-dentate alumina support based ligands, adsorbed on cobalt surfaces. We find that the presence of the ligand may significantly affect the morphology of a cobalt crystallite. With Fischer-Tropsch synthesis in mind, the CO dissociation is used as a probe reaction, with the ligand assisting the dissociation, making it feasible to dissociate CO on the dense fcc Co(111) surface. The nature of the interaction between the ligand and the probe molecule is characterized, showing that the support-like ligands' metal centre is directly interacting with the probe molecule.

Co2C nanoprisms with strong facet effect for Fischer-Tropsch to olefins reaction

Lower olefins refer to ethylene, propylene and butylene, which are vital building block in the chemical industry. They are fundamental chemicals of the greatest consumption among the organic chemicals all over the world. Large amount of chemical products, such as packing materials, cosmetics, synthetic rubber, coatings are the derivatives of lower olefins. In traditional petrochemical industry, lower olefins are mainly derived from oil-based feedstocks. With the rapid depletion of the limited petroleum, there is an urgent need for processes that can produce lower olefins from alternative feedstocks. The syngas, which is a promising alternative feedstock as it can be obtained from reforming of natural gas, gasification of coal or biomass, can be transformed into lower olefins through indirect or direct reaction. The indirect process mainly refers to the methanol to olefins (MTO) technology [1]. The direct conversion of syngas to lower olefins is one of the most challenging subjects in the field of C1 chemistry. It is considered as an attractive alternative non-petroleum-based production route due to its process simplicity and low energy consumption [2]. Bifunctional catalysis used composite catalysts, such as OX-ZEO and Fischer-Tropsch to olefins (FTO) reaction are twomain routes for the direct conversion of syngas to lower olefins [3]. Recent work by Bao et al. [4] and Wang et al. [5] reported that oxides-molecular sieve coupling catalysts exhibited very high selectivity toward lower olefins at relative high temperature of ca. 400°C, but this method is not yet in commercial use. As the reaction process for FTO is very similar to that for typical FT synthesis, FT catalysts can be used for production of lower olefins after suitable catalyst modification. De Jong et al. [6] reported that Fe-based catalysts promoted by S andNa and using α-alumina or carbon nanofiber as weakly interactive supports exhibited excellent performance for selective formation of lower olefins (61 C%). They also found the particle size of iron carbide plays a crucial role for direct production of lower olefins via syngas, and they suggested lower olefins are produced at promoted terrace sites [7]. However, these reactions normally need temperatures from 300°C to 350°C, which would cause carbon deposition on the catalyst surface and catalyst sintering, deactivating the catalyst and shortening its lifetime [2]. The primary aims of FTO are to maximize lower olefins selectivity while reduce methane production with high stability. The maximum selectivity toward C2−C4 olefins is achieved with an alpha value of about 0.5 according to the ordinary Anderson–Schulz–Flory (ASF) model [8,9]. One of the most efficient ways of shifting product selectivity to low alpha values is by increasing reaction temperature. However, a decrease on the chain growth probability results in an increase of methane selectivity as indicated by the ASF product distribution. In addition, the produced olefins were prone to be further hydrogenated to paraffins especially at high temperature and resulted in decreased selectivity to lower olefins. Moreover, the particle sintering and coke formation at high temperature would lead to serious deactivation [10]. Due to the above limitation, there was no catalyst suitable for the industrial application of the direct conversion of syngas into lower olefins via the Fischer-Tropsch synthesis. Based on the general analysis, most of the reported FTO catalysts are still a kind of FT catalyst with low alpha value. The product distribution still obeys the ordinary ASF model. Obviously, with the goal of high selectivity to lower olefin, lowmethane selectivity and high stability simultaneously, it is necessary to develop new FTO catalyst which deviates from ASF distribution at mild reaction conditions.

The effect of SiO2 particle size on iron based F–T synthesis catalysts

The effect of particle size of silica, as catalyst binder, on the chemical and mechanical properties of iron based FT catalyst was studied in this work. The samples were characterized using XRD, BET, TEM, FT-IR, and H2-TPR, respectively. The attrition resistance and the FT activity were tested. Si-8–Si-15 catalysts prepared with 8–15nm silica sol show good attrition resistance (attrition loss<4%), especially Si-13 with an attrition loss of 1.89%. Hematite appeared in XRD patterns when silica sol above 15nm is used. TEM micrographs show that no obvious SiO2 particles appear when silica sol particle with size less than 8nm was used, but SiO2 particles coated with small ferrihydrite particles appear when silica sol above 8nm was used. Si–O–Si vibration peak in FT-IR spectra increases with increasing silica sol size. Samples prepared with silica sol show good stability of FT reactions, and the average molecular weight of FT products increases with the increase of SiO2 particle.

Iron Fischer-Tropsch Catalysts Prepared by Solvent-Deficient Precipitation (SDP): Effects of Washing, Promoter Addition Step, and Drying Temperature

A novel, solvent-deficient precipitation (SDP) method for catalyst preparation in general and for preparation of iron FT catalysts in particular is reported. Eight catalysts using a 23 factorial design of experiments to identify the key preparation variables were prepared. The catalysts were characterized by electron microprobe, N2 adsorption, TEM, XRD, and ICP. Results show that the morphology of the catalysts, i.e., surface area, pore volume, pore size distribution, crystallite sizes, and promoter distribution are significantly influenced by (1) whether or not the precursor catalyst is washed, (2) the promoter addition step, and (3) the drying condition (temperature). Consequently, the activity, selectivity, and stability of the catalysts determined from fixed-bed testing are also affected by these three variables. Unwashed catalysts prepared by a one-step method and dried at 100 °C produced the most active catalysts for FT synthesis. The catalysts of this study prepared by SDP compared favorably in activity, productivity, and stability with Fe FT catalysts reported in the literature. It is believed that this facile SDP approach has promise for development of future FT catalysts, and also offers a potential alternate route for the preparation of other catalysts for various other applications.

Elucidation of reaction network of higher alcohol synthesis over modified FT catalysts by probe molecule experiments

The reaction network of high alcohol synthesis over a CuFe/ZrO2 modified FT catalyst was investigated by the probe molecule technique.

The Conversion of Syngas to Liquid Fuels in a Dual-Bed Single Reactor Process

The effects of HZSM-5 temperature and weight hourly space velocity (WHSV) on conversion of syngas to liquid fuels were investigated in a single reactor process. The temperature of FT catalyst was constant (463 K), whereas the temperature of HZSM-5 varied (523, 573, 623 K). The value of WHSV ranged between 16 and 24 h−1. HZSM-5 addition suppressed the formation of CH4 and remarkably enhanced the formation of iso-C5-C12 paraffins. An increase of HZSM-5 temperature resulted in an enhancement of gaseous hydrocarbons, C18+ paraffins, and olefins. The optimal HZSM-5 temperature and WHSV were identified as 523 K and 16 h−1, respectively.