Design novel inorganic precursors for producing clean fuels by using Fischer-Tropsch synthesis

A new metal-organic framework compound formulated as [Co_0.67Zn_0.83(btc)(H₂O)₆] (1) was prepared and characterized by elemental analysis, and FT-IR spectroscopy. The single crystal analysis was used for determination of its structure. The complex was used for the preparation of two inorganic precursors [Co_0.67Zn_0.83(btc)(H₂O)₆]/SiO₂ and [Co_0.67Zn_0.83(btc)(H₂O)₆]/Al₂O₃, which were thermally decomposed to obtain new Co-Zn alloy catalysts for Fischer-Tropsch synthesis. The same catalysts were prepared by the conventional impregnation method as reference catalysts. The catalysts were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and BET specific surface area, and their catalytic performances were studied in the temperature range 200–300 °C and P = 5 bar. The results show that the Co-Zn synthesized alloy catalysts have acceptable activity in the Fischer-Tropsch (FTS) synthesis and have better selectivity to desired products than reference catalysts. The difference between the Co-Zn alloy catalysts and the reference catalysts is mainly caused by their different particle size.     

Characterization and catalytic behavior of EDTA modified silica nanosprings (NS)-supported cobalt catalyst for Fischer-Tropsch CO-hydrogenation

The effect of ethylene diamine tetraacetic acid(EDTA) modification on the physico-chemical properties and catalytic performance of silica nanosprings(NS) supported cobalt(Co) catalyst was investigated in the conversion of syngas(H~(2+) CO) to hydrocarbons by Fischer-Tropsch synthesis(FTS). The unmodified Co/NS and modified Co/NS-EDTA catalysts were synthesized via an impregnation method. The prepared Co/NS and Co/NS-EDTA catalysts were characterized before the FTS reaction by BET surface area,X-ray diffraction(XRD),transmission electron microscopy(TEM),temperature programmed reduction(TPR),X-ray photoelectron spectroscopy(XPS),differential thermal analysis(DTA) and thermogravimetric analysis(TGA) in order to find correlations between physico-chemical properties of catalysts and catalytic performance. FTS was carried out in a quartz fixedbed microreactor(H_2/CO of 2 ∶1,230 ℃ and atmospheric pressure) and the products trapped and analyzed by GC-TCD and GC-MS to determine CO conversion and reaction selectivity. The experimental results indicated that the modified Co/NS-EDTA catalyst displayed a more-dispersed phase of Co_3O_4 nanoparticles(10.9%) and the Co_3O_4 average crystallite size was about 12.4 nm. The EDTA modified catalyst showed relatively higher CO conversion(70.3%) and selectivity toward C_(6-18)(JP-8,Jet A and diesel) than the Co/NS catalyst(C_(6-14))(JP-4).     

气相色谱法测定费托合成水相产物中的低碳醇、醛、酮化合物

建立了铁基催化剂费托合成反应水相产物中低碳(C₁~C₈)醇、醛、酮的气相色谱测定方法.对色谱分离条件进行了优化,确立了以乙醇为基准物质并结合各组分校正因子的定量方法;考察了方法的精密度和准确度,并对费托合成反应水相产物样品进行了测定.结果表明,乙醇在不同的含量范围内呈现良好的线性关系,相关系数均大于0.99.费托合成水相产物中的加标回收率在93.4%~109.6%之间,准确性可以满足实际分析的需要.实际费托合成水相产物的分析结果表明,费托合成水相产物中主要的低碳醇、醛、酮的总质量分数约为3%~12%,乙醇含量最高(约为1.7%~7.3%),且正构醇、异构醇和醛酮类化合物所占的总比率依次降低.该方法简单、快速,对费托合成水相产物中重要组分的分析有重要意义.     

Synthesis and properties of Na6[Pb(S2O3)4] · 6H2O

Conditions for the synthesis of the water-soluble lead thiosulfate complex Na₆[Pb(S₂O₃)₄] · 6H₂O were determined. The complex synthesized was characterized by UV and IR spectroscopy and X-ray phase and thermal analyses. Thermolysis schemes were proposed on the basis of the IR and mass spectra of the thermal decomposition products.     

Fischer-Tropsch synthesis catalysts as the core of the strategy for obtaining synthetic liquid fuels

The Fischer-Tropsch synthesis is a practically significant reaction catalyzed by Fe and Co, which are active at different H₂: CO ratios of 0.5 and 2, respectively. For this reason, Fe-containing catalysts are preferentially used in coal-to-liquids (CTL) and biomass-to-liquids (BTL) processes, while Co-containing catalysts are preferred for the gas-to-liquids (GTL) technology. With the Fe catalysts, which are remarkable for their high CO₂ formation selectivity, it is appropriate to carry out the carbon dioxide reforming of the feedstock.     

Mass- and heat-transfer-enhanced catalyst system for Fischer-Tropsch synthesis in fixed-bed reactors

Fischer-Tropsch synthesis (FTS) was carried out using Al₂O₃-supported Co catalyst coated on metallic monolith. Considering the liberation of a large amont of heat from the highly exothermic FTS reaction, catalytic activity of Co catalyst coated on metallic monolith was tested and compared with that of pellet-type catalysts. The reaction was carried out in a conventional tubular fixed-bed reactor and simulated distillation (SIMDIS) analysis method was used to determine the liquid products distribution. Proper control of degree of reaction, as well as the reaction temperature gave rise to a shift of products selectivity toward higher hydrocarbons, especially C₁₃?C₁₈ diesel range hydrocarbons.     

Effects of promoters on catalytic performance of Fe-Co/SiO2 catalyst for Fischer-Tropsch synthesis

2%Fe-10%Co/SiO₂ catalysts with different potassium or zirconium loadings were prepared by aqueous incipient wetness impregnation and tested for Fischer-Tropsch synthesis in a flow reactor, using H₂/CO = 1.6 (molar ratio) in the feed, under the condition of an overall pressure of 1 MPa, GHSV of 600 h⁻¹ and temperature of 503 K. The zirconium and potassium promoters remarkably influenced hydrocarbon distribution of the products. CO conversion increased on the catalysts with the increase of zirconium loadings, which indicated that zirconium enhanced the activity of iron-cobalt catalysts. Low potassium loadings also enhanced the activity of the catalysts. However, high potassium loading made CO conversion on the catalysts decrease and weakened the secondary hydrogenations. The catalyst was characterized by BET, XRD and TPR. The catalyst characterization revealed that the Co₃O₄ phase was presented on the fresh catalyst, whereas the spinel phase of Fe-Co alloy and CoO existed on the used catalyst.     

Catalytic properties of Ru nanoparticles embedded on ordered mesoporous carbon with different pore size in Fischer-Tropsch synthesis

A series of 3 wt% Ru embedded on ordered mesoporous carbon (OMC) catalysts with different pore sizes were prepared by autoreduction between ruthenium precursors and carbon sources at 1123 K. Ru nanoparticles were embedded on the carbon walls of OMC. Characterization technologies including power X-ray diffraction (XRD), nitrogen adsorption-desorption, transmission electron microscopy (TEM), and hydrogen temperature-programmed reduction (H₂-TPR) were used to scrutinize the catalysts. The catalyst activity for Fischer-Tropsch synthesis (FTS) was measured in a fixed bed reactor. It was revealed that 3 wt% Ru-OMC catalysts exhibited highly ordered mesoporous structure and large surface area. Compared with the catalysts with smaller pores, the catalysts with larger pores were inclined to form larger Ru particles. These 3 wt% Ru-OMC catalysts with different pore sizes were more stable than 3 wt% Ru/AC catalyst during the FTS reactions because Ru particles were embedded on the carbon walls, suppressing particles aggregation, movement and oxidation. The catalytic activity and C₅₊ selectivity were found to increase with the increasing pore size, however, CH₄ selectivity showed the opposite trend. These changes may be explained in terms of the special environment of the active Ru sites and the diffusion of products in the pores of the catalysts, suggesting that the activity and hydrocarbon selectivity are more dependent on the pore size of OMC than on the Ru particle size.     

Formation of Co-Ru/MgO/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalysts for the Fischer-Tropsch synthesis: A magnetic method for the estimation of cobalt particle size

The physicochemical properties of Co-supported catalysts were studied, and the particle size of Co in Co/MgO/Al₂O₃ and Co-0.2% Ru/MgO/Al₂O₃ catalysts for the Fischer-Tropsch synthesis (FTS) was estimated using a magnetic method. It was found that a considerable fraction of superparamagnetic Co particles, which increase selectivity for C₅₊ hydrocarbons and decrease the yield of methane in the FTS, was present in a ruthenium-containing catalyst along with single-domain ferromagnetic particles. In this case, the catalyst activity increased by a factor of 10.     

Some selected chapters from the (butadiene)zirconocene story

(Butadiene)zirconocene was the first mono-nuclear metal complex for which the s-trans-η⁴-conjugated diene coordination mode was established. Meanwhile a variety of additional examples from metals throughout the Periodic Table was found. The (butadiene)zirconocenes have found use as valuable reagents in organic and organometallic synthesis, for which various representative examples are described. They have also found extensive use as precursors for the generation of very active and sometimes very selective homogeneous metallocene Ziegler-Natta olefin polymerization catalysts. The employment of the dipolar zirconocene(butadiene)/B(C₆F₅)₃ addition products in mechanistic studies has revealed important aspects of the reaction course taken in the carbon-carbon coupling reaction sequences at this important class of catalysts. Several specific examples are described in this article.     

Ni助剂FeMnK/SiO2费托合成催化剂的结构性质及还原碳化行为研究

研究了Ni助剂对共沉淀型FeMnK/SiO2催化剂的结构性质和还原炭化行为的影响。结果表明，添加少量Ni助剂提高了催化剂的比表面积，降低了平均孔径，促进了催化剂中铁氧化物的分散。在H2-TPR中，Ni助剂降低了催化剂的还原温度；在CO-TPR中，Ni助剂使催化剂的还原和炭化峰前移，提高了氧的移除速率，增加了碳的引入量；在合成气等温还原中，Ni助剂提高了催化剂的活化速率，在相同的还原时间内可获得更高的F-T合成反应活性。     

Fischer-Tropsch synthesis over Ru/Al2O3 catalysts

Fischer-Tropsch syntheses (FTS) were carried out in a slurry phase over Ru/Al₂O₃ catalysts using hexadecane as a solvent. The outcome of the FTS was dependent on the oxide support, calcination temperature, synthesis gas composition and sulfur content. The addition of Mn/Na to Ru/Al₂O₃ was effective in raising the initial activity and C5+ selectivity, but after 20 hours, the performance of the modified catalyst was similar to that of the unmodified catalyst. An additional investigation involving the use of fresh vs used catalysts demonstrated that an agglomeration of the metallic Ru, at least in part, does occur during the reaction.     

Fuzzy model prediction of Co (III)Al2O3 catalytic behavior in Fischer-Tropsch synthesis

The application of Co(Ⅲ)/Al2O3 catalyst in Fischer-Tropsch synthesis(FTS)was studied in a wide range of synthesis gas conversions and compared with Fuzzy Simulation results.Present study applies fuzzy model to predicting the product composition of CH4,CO2 and CO in Fischer-Tropsch process for natural gas synthesis,in which the input vector was 4-dimension including four variables(operating pressure, operating temperature,time and CO/H2 ratio)of 70 different experiments and the output product is a composition of CO2,CO and CH4. The Mamdani algorithm has been applied to the training of the fuzzy system and the test set was used to evaluate the performance of the system including R2,ARE,AARE and SD.The results demonstrated that the predicted values from the model were in good consistency with the experimental data.The work indicates how fuzzy inference system(FIS),as a promising predicting technique,would be effectively used in FTS.     

Nanosized cobalt-based catalyst prepared by supercritical phase condition for Fischer-Tropsch synthesis

A series of nanosized Co/Zn/Mn/K composite catalysts for Fischer-Tropsch synthesis (FTS) were prepared by supercritical fluid drying (SCFD) method and common drying (CD) method. The nanosized cobalt-based catalysts were characterized by XRD, TEM and BET techniques. Their catalytic performances were tested in a slurry-bed reactor under FTS reaction conditions. The drying and crystallization were carried out simultaneously during SCFD, therefore, the catalysts prepared by SCFD method have ideal structure and show the FTS performance superior to the others prepared by CD method. The FTS activity and selectivity were improved via adding Zn, Mn and K promoters, and less CH₄ and CO₂ as well as higher yield of C₅₊ products were achieved. The optimal performance of a 92% CO conversion and a 65% C₅₊ product yield was obtained over a catalyst with the component of Co/Zn/Mn/K = 100/50/10/7. Furthermore, the catalytic performance was studied under the conditions of liquid-phase and supercritical phase slurry-bed, and C₅₊ product yield were 57.4% and 65.4%, respectively. In summary, better catalytic performance was obtained using the nanosized catalyst prepared by SCFD method under supercritical reaction conditions, resulting in higher conversion of CO, less CO₂ byproduct, and higher yield of C₅₊ products.     

Effect of La2O3 on a Precipitated Iron Catalyst for Fischer-Tropsch Synthesis

A series of La₂O₃-promoted precipitated iron catalysts (100Fe/2.8Si/nLa, n = 0, 0.5, 1, 2, and 4, atomic ratio) were prepared and characterized by in situ X-ray diffraction, CO temperature-programmed reduction, and N₂ adsorption-desorption. The catalytic performance for Fischer-Tropsch synthesis was studied in a fixed-bed reactor. It was found that the addition of a small amount of La₂O₃ (La/Fe ≤ 0.01) gave a large decrease in the particle size of Fe₂O₃, which increased the specific surface area and dispersion of the catalysts. This also favored the formation of iron carbides, which gave a high catalytic activity in Fischer-Tropsch synthesis. With increasing La₂O₃ content (La/Fe ≥ 0.02), a high La₂O₃ coverage and the formation of a LaFeO₃ compound decreased the formation of iron carbides, and the reaction activity decreased. The optimum La₂O₃ content was La/Fe = 0.01. The addition of La₂O₃ increased the selectivity for methane and suppressed the formation of C₅₊ hydrocarbons.     

Effect of the composition and structure of the precursor compound on the catalytic properties of cobalt-aluminum catalysts in the Fischer-Tropsch synthesis

The effect of preparation procedure on the anionic composition and structure of hydroxo compounds as precursors of Co-Al catalysts and on their catalytic properties in the Fischer-Tropsch synthesis was studied. The dynamics of changes in the composition and structure of the hydroxide precursors of Co-Al catalysts during thermal treatment and subsequent activation was studied by thermal analysis, IR spectroscopy, XRD analysis, and in situ XRD analysis with the use of synchrotron radiation. It was found that the precursor compounds prepared by deposition-precipitation of cobalt cations on γ- and δ-Al₂O₃ under urea hydrolysis conditions, which had a hydrotalcite-type structure and contained nitrate, carbonate, and hydroxyl groups, turtned into the oxide compounds Co_{3 ? x} Al _x O₄ (0 < x < 2) with the spinel structure in the course of thermal treatment in an inert atmosphere. The hydrogen activation of an oxide precursor led to the formation of cobalt metal particles through the intermediate formation of a cobalt(II)-aluminum oxide phase. The catalyst was characterized by high activity and selectivity for C₅₊ hydrocarbons in the Fischer-Tropsch synthesis.     

TiO2 supported cobalt-manganese nano catalysts for light olefins production from syngas

Cobalt-manganese nano catalysts were prepared by sol-gel method. This research investigated the effects of different cobalt-manganese (Co/Mn = 1/1) loading, pH and calcination conditions on the catalytic performance of Co-Mn/TiO₂ catalysts for Fischer-Tropsch synthesis (FTS) in a fixed bed reactor. It was found that the catalyst containing 30wt%(Co-Mn)/TiO₂ was an optimal catalyst for the conversion of synthesis gas to light olefins especially propylene. The activity and selectivity of optimal catalyst were studied under different operational conditions. The results showed that the best operational conditions were H₂/CO= 1/1 molar feed ratio at 250 °C and GHSV= 1300 h^?1 under atmospheric pressure. Characterization of catalysts was carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N₂ adsorption-desorption measurements.     

以钴羰基簇合物为前驱体制备的钴基催化剂上F-T反应性能简

以含羧酸配体的钴羰基簇合物Co₂（CO）₆HCCCOOH,Co₃（CO）₉CCH₂COOH,Co₄（CO）₁₀HCCCOOH 为前驱体,γ-Al₂O₃为载体,通过浸渍法制备了一系列催化剂;同时以Co（NO₃）₂作为前驱体制备了参比催化剂. 对制备的催化剂进行了费托反应性能评价,并用透射电子显微镜、氨程序升温脱附和傅里叶变换红外光谱等手段对催化剂进行了表征. 结果发现,不同前驱体制备的催化剂对载体上Co的分布具有明显影响,进而影响催化剂活性. 反应结果表明,不同前驱体制备的催化剂上CO转化率及C₅₊选择性顺序为Co₃（CO）₉CCH₂COOH > Co₂（CO）₆HCCCOOH > Co₄（CO）₁₀HCCCOOH > Co（NO₃）₂.     

Reactions of carbonyl clusters with heterobidentate ligands. Synthesis and structural characterization of H4Ru4(CO)10[k2(P,S)-Ph2P(2-CH3SC6H4)] and Rh6(CO)14[k2(P,S)-Ph2P(2-CH3SC6H4)] clusters

Two new disubstituted derivatives of the clusters Rh₆(CO)₁₆ and H₄Ru₄(CO)₁₂ with the heterobidentate ligand [Ph₂P(2-CH₃SC₆H₄)] were synthesized. Structures of these compounds were completely characterized both in solid phase and solution. The H₄Ru₄(CO)₁₀[k²(P,S)-Ph₂P(2-CH₃SC₆H₄)] cluster is an example of a structure, in which a chelating coordination of a heterobidentate ligand results in the occurrence of a center of asymmetry associated with the substituted metal atom. This type of polynuclear complexes is of interest for obtaining essentially new catalysts for asymmetric synthesis on the basis of cluster compounds.     

Double complex salts [Ni(NH3)6]3[Fe(CN)6]2 and [Ni(NH3)6]3[Cr(CNS)6]2: Synthesis and properties

The double complex salts [Ni(NH₃)₆]₃[Fe(CN)₆]₂ and [Ni(NH₃)₆]₃[Cr(CNS)₆]₂ were synthesized and their thermal decomposition in air was studied. The values of interplanar distances in crystal lattices were determined. The compounds are proposed as precursors for producing homogeneous bimetallic nanodimensional powders.