过刊目录

2009, Vol. 18, No. 2　Online: 2009-03-30

上一期    下一期

全全选选:

导出引用 EndNote Ris BibTeX

隐藏/显示图片

Articles

Select

Catalytic Ignition of Light Hydrocarbons K. L. Hohn;C.-C. Huang;C. Cao 2009, 18(2): 115-123.  DOI: 摘要 ( 8612 )   PDF   Catalytic ignition refers to phenomenon where sufficient energy is released from a catalytic reaction to maintain further reaction without additional external heating. This phenomenon is important in the development of catalytic combustion and catalytic partial oxidation processes, both of which have received extensive attention in recent years. In addition, catalytic ignition studies provide experimental data which can be used to test theoretical hydrocarbon oxidation models. For these reasons, catalytic ignition has been frequently studied. This review summarizes the experimental methods used to study catalytic ignition of light hydrocarbons and describes the experimental and theoretical results obtained related to catalytic ignition. The role of catalyst metal, fuel and fuel concentration, and catalyst state in catalytic ignition are examined, and some conclusions are drawn on the mechanism of catalytic ignition.

Select

Transformation of methane to synthesis gas over metal oxides without using catalyst Reza Alizadeh*;Esmail Jamshidi;Guangqing Zhang 2009, 18(2): 124-130.  DOI: 摘要 ( 10805 )   PDF   This article reviews a new developing method in the field of metal oxide reduction in chemical and metallurgical processes, which uses methane as a reducing agent. Commonly, coal is used as the reducing agent in the reduction of metal oxide and other inorganic materials; Metal producing factories are among the most intensive and concentrated source of greenhouse gases and other pollutants such as heavy metals, sulfur dioxide and fly ash. Thermodynamically, methane has a great reducing capability and can be activated to produce synthesis gas over a metal oxide as an oxygen donor. Metal oxide reduction and methane activation, two concurrent thermochemical processes, can be combined as an efficient and energy-saving process; nowadays this kind of technologies is of great importance. This new reduction process could improve energy efficiencies and significantly decrease greenhouse gas emission compared to the conventional process; furthermore, the produced gases are synthesis gas that is more valuable than methane. In this paper, thermodynamic studies and advantages of this promising method were discussed. The major aim of this article is to introduce methane as a best and environmentally friendly reducing agent at low temperature.

Select

La2−xCexCu1−yZnyO4 perovskites for high temperature water-gas shift reaction S. S. Maluf;E. M. Assaf* 2009, 18(2): 131-138.  DOI: 摘要 ( 7224 )   PDF   The performance of La2−xCexCu1−yZnyO4 perovskites as catalysts for the high temperature water-gas shift reaction (HT-WGSR) was investigated. The catalysts were characterized by EDS, XRD, BET surface area, TPR, and XANES. The results showed that all the perovskites exhibited the La2CuO4 orthorhombic structure, so the Pechini method is suitable for the preparation of pure perovskite. However, the La1.90Ce0.10CuO4 perovskite alone, when calcined at 350/700 ◦C, also showed a (La0.935Ce0.065)2CuO4 perovskite with tetragonal structure, which produced a surface area higher than the other perovskites. The perovskites that exhibited the best catalytic performance were those calcined at 350/700 ◦C and, among these, La1.90Ce0.10CuO4 was outstanding, probably because of the high surface area associated with the presence of the (La0.935Ce0.065)2CuO4 perovskite with tetragonal structure and orthorhombic La2CuO4 phase.

Select

CeO2-ZrO2-La2O3-Al2O3 composite oxide and its supported palladium catalyst for the treatment of exhaust of natural gas engined vehicles Xiaoyu Zhang;Enyan Long;Yile Li;Jiaxiu Guo;Lijuan Zhang;Maochu Gong;Minghua Wang;Yaoqiang Chen* 2009, 18(2): 139-144.  DOI: 摘要 ( 12418 )   PDF   Composite supports CeO2-ZrO2-Al2O3 (CZA) and CeO2-ZrO2-Al2O3-La2O3 (CZALa) were prepared by co-precipitation method. Palladium catalysts were prepared by impregnation and their purification ability for CH4, CO and NOx in the mixture gas simulated the exhaust from natural gas vehicles (NGVs) operated under stoichiometric condition was investigated. The effect of La2O3 on the physicochemical properties of supports and catalysts was characterized by various techniques. The characterizations with X-ray diffraction (XRD) and Raman spectroscopy revealed that the doping of La2O3 restrained effectively the sintering of crystallite particles, maintained the crystallite particles in nanoscale and stabilized the crystal phase after calcination at 1000 ℃. The results of N2-adsorption, H2-temperature-programmed reduction (H2-TPR) and oxygen storage capacity (OSC) measurements indicated that La2O3 improved the textural properties, reducibility and OSC of composite supports. Catalytic activity testing results showed that the catalysts exhibit excellent activities for the simultaneous removal of methane, CO and NOx in the simulated exhaust gas. The catalysts supported on CZALa showed remarkable thermal stability and catalytic activity for the three pollutants, especially for NOx. The prepared palladium catalysts have high ability to remove NOx, CH4 and CO, and they can be used as excellent catalysts for the purification of exhaust from NGVs operated under stoichiometric condition. They also have significant potential in industrial application because of their high performance and low cost.

Select

Reduced combustion time model for methane in gas turbine flow fields Mouna Lamnaouer;Robert C. Ryder;Andreja Brankovic;Eric L. Petersen* 2009, 18(2): 145-155.  DOI: 摘要 ( 8020 )   PDF   Computational fluid dynamics modeling of the complex processes that occur within the burner of a gas turbine engine has become a critical step in the design process. However, due to computer limitations, it is very difficult to completely couple the fluid mechanics solver with the full combustion chemistry. Therefore, simplified chemistry models are required, and the topic of this research was to provide reduced chemistry models for CH4/O2 gas turbine flow fields to be integrated into CFD codes for the simulation of flow fields of natural gas-fueled burners. The reduction procedure for the CH4/O2 model utilized a response modeling technique wherein the full mechanism was solved over a range of temperatures, pressures, and mixture ratios to establish the response of a particular variable, namely the chemical reaction time. The conditions covered were between 1000 and 2500 K for temperature, 0.1 and 2 for equivalence ratio in air, and 0.1 and 50 atm for pressure. The kinetic time models in the form of ignition time correlations are given in Arrhenius-type formulas as functions of equivalence ratio, temperature, and pressure; or fuel-to-air ratio, temperature, and pressure. A single ignition time model was obtained for the entire range of conditions, and separate models for the low-temperature and high-temperature regions as well as for fuel-lean and rich cases were also derived. Predictions using the reduced model were verified using results from the full mechanism and empirical correlations from experiments. The models are intended for (but not limited to) use in CFD codes for flow field simulations of gas turbine combustors in which initial conditions and degree of mixedness of the fuel and air are key factors in achieving stable and robust combustion processes and acceptable emission levels. The chemical time model was utilized successfully in CFD simulations of a generic gas turbine combustor with four different cases with various levels of fuel-air premixing.

Select

Effect of acid density of HZSM-5 on the oligomerization of ethylene in FCC dry gas Xue Ding;Shan Geng;Chunyi Li*;Chaohe Yang;Guohui Wang 2009, 18(2): 156-160.  DOI: 摘要 ( 8200 )   PDF   The oligomerization of ethylene in FCC dry gas over HZSM-5 catalyst with different Si/Al2 ratios was studied. The effect of acid density of catalyst on the oligomerization of ethylene was discussed. By increasing the acid density of catalyst, ethylene conversion showed a linear increase, while the yields of olefins decreased when the acid density of catalyst exceeded 0.14 mmolNH3 /g owing to a promotion of hydrogen transfer reaction. Through comparing the average distance between acid sites on catalyst with kinetic diameters of olefins, it was found that the dimerization of ethylene was not restrained by the sparse distribution of acid sites, while the hydrogen transfer reaction of C3 and C4 olefins was limited. On these bases, a conclusion is proposed that the dimerization of ethylene proceeded via Eley-Rideal mechanism, while the hydrogen transfer reaction of C3 and C4 olefins followed the Langmuir-Hinshelwood mechanism.

Select

Effect of Mg/Al atom ratio of support on catalytic performance of Co-Mo/MgO-Al2O3 catalyst for water gas shift reaction Yixin Lian;Huifang Wang;Quan-xing Zheng;Weiping Fang;Yiquan Yang* 2009, 18(2): 161-166.  DOI: 摘要 ( 7533 )   PDF   Co-Mo-based catalysts supported on mixed oxide supports MgO-Al2O3 with different Mg/Al atom ratios for water gas shift reaction were prepared and studied by means of TPR, Raman, XPS and ESR. It was found that the octahedral Mo species in oxidic Co-Mo/MgO(x)-Al2O3 catalyst and the contents ofMo5+, Mo4+, S2− and S2−2 species in the functioning catalysts increased with increasing theMg/Al atom ratio of the support under the studied experimental conditions. This is propitious for the formation of the active Co-Mo-S phase of the catalysts. Catalytic performance testing results showed that the catalysts Co-Mo/MgO-Al2O3 with theMg/Al atom ratio of the support in the range of 0.475−0.525 exhibited optimal catalytic activity for the reaction.

Select

Adsorption separation of carbon dioxide, methane and nitrogen on monoethanol amine modified B-zeolite Xiaoliang Xu;Xingxiang Zhao;Linbing Sun;Xiaoqin Liu* 2009, 18(2): 167-172.  DOI: 摘要 ( 9032 )   PDF   A new type of composite adsorbents was synthesized by incorporating monoethanol amine (MEA) into B-zeolite. The parent and MEAfunctionalized B-zeolites were characterized by X-ray diffraction (XRD), N2 adsorption, and thermogravimetric analysis (TGA). The adsorption behavior of carbon dioxide (CO2), methane (CH4), and nitrogen (N2) on these adsorbents was investigated at 303 K. The results show that the structure of zeolite was well preserved after MEA modification. In comparison with CH4 and N2, CO2 was preferentially adsorbed on the adsorbents investigated. The introduction of MEA significantly improved the selectivity of both CO2/CH4 and CO2/N2, the optimal selectivity of CO2/CH4 can reach 7.70 on 40 wt% of MEA-functionalized B-zeolite (MEA(40)-B) at 1 atm. It is worth noticing that a very high selectivity of CO2/N2 of 25.67 was obtained on MEA(40)-B. Steric effect and chemical adsorbate-adsorbent interaction were responsible for such high adsorption selectivity of CO2. The present MEA-functionalized B-zeolite adsorbents may be a good candidate for applications in flue gas separation, as well as natural gas and landfill gas purifications.

Select

Removal of CO from reformed fuels by selective methanation over Ni-B-Zr-O catalysts Qihai Liu;Xinfa Dong*;Yibing Song;Weiming Lin 2009, 18(2): 173-178.  DOI: 摘要 ( 7751 )   PDF   The Ni-B-Oδ andNi-B-Zr-Oδ catalysts were prepared by the method of chemical reduction, and the deep removal of CO by selective methanation from the reformed fuels was performed over the as-prepared catalysts. The results showed that zirconium strongly influenced the activity and selectivity of the Ni-B-Zr-Oδ catalysts. Over the Ni-B-Oδ catalyst, the highest CO conversion obtained was only 24.32% under the experimental conditions studied. However, over the Ni-B-Zr-Oδ catalysts, the CO methanation conversion was higher than 90% when the temperature was increased to 220 oC. Additionally, it was found that the Ni/B mole ratio also affected the performance of the Ni-B-Zr-Oδ catalysts. With the increase of the Ni/B mole ratio from 1.8 to 2.2, the CO methanation activity of the catalyst was improved. But when the Ni/B mole ratio was higher than 2.2, the performance of the catalyst for CO selective methanation decreased instead. Among all the catalysts, the Ni29B13Zr58Oδ catalyst investigated here exhibited the highest catalytic performance for the CO selective methanation, which was capable of reducing the CO outlet concentration to less than 40 ppm from the feed gases stream in the temperature range of 230–250 oC, while the CO2 conversion was kept below 8% all along. Characterization of the Ni-B-Oδ and Ni-B-Zr-Oδ catalysts was provided by XRD, SEM, DSC, and XPS.

Select

Synthesis and applications of mesoporous Cu-Zn-Al2O3 catalyst for dehydrogenation of 2-butanol Deren Fang;Wanzhong Ren;Zhongmin Liu*;Xiufeng Xu;Lei Xu;Hongying Lv;Weiping Liao;Huimin Zhang 2009, 18(2): 179-182.  DOI: 摘要 ( 7924 )   PDF   A series of mesoporous Cu-Zn-Al2O3 materials have been synthesized at ambient temperature and their structure was characterized by XRD, N2 physical adsorption and TPR techniques. Their catalytic applications for the dehydrogenation of 2-butanol to methyl ethyl ketone (MEK) were evaluated in a fixed-bed flow reactor at atmospheric pressure. It is demonstrated from the XRD patterns that both the as-synthesized samples and calcined samples have the typical XRD patterns of meso-structured materials and the results of N2O chemical adsorption showed that Cu was embedded in the framework of the mesoporous materials and homogeneously dispersed in the mesoporous Cu-Zn-Al2O3 materials. The catalytic activity of 2-butanol dehydrogenation was varied in the order of CZA(10)

Select

Nickel and potassium co-modified -Mo2C catalyst for CO conversion Minglin Xiang;*;Juan Zou;Debao Li;Wenhuai Li;Yuhan Sun*;Xichun She 2009, 18(2): 183-186.  DOI: 摘要 ( 7136 )   PDF   Nickel and potassium co-modified -Mo2C catalysts were prepared and used for CO hydrogenation reaction. The major products over -Mo2C were C1–C4 hydrocarbons, only few alcohols were obtained. Addition of potassium resulted in remarkable selectivity shift from hydrocarbons to alcohols at the expense of CO conversion over -Mo2C. Moreover, it was found that potassium enhanced the ability of chain propagation with a higher C2+OH production. Modified by nickel, -Mo2C showed a relatively high CO conversion, however, the products were similar to those of pure -Mo2C. When co-modified by nickel and potassium, -Mo2C exhibited high activity and selectivity towards mixed alcohols synthesis, and also the whole chain propagation to produce alcohols especially for the stage of C1OH to C2OH was remarkably enhanced. It was concluded that the Ni and K had, to some extent, synergistic effect on CO conversion.

Select

Suppression of methane formation during Fisher-Tropsch synthesis using manganese-cobalt oxide supported on H-5A zeolite as a catalyst Syed Tajammul Hussain;Muhammad Mazhar;Muhammad Arif Nadeem 2009, 18(2): 187-190.  DOI: 摘要 ( 10463 )   PDF   In Fischer-Tropsch synthesis reaction, methane formation is one of the side reactions which must be suppressed in order to get better catalytic dselectivity for light olefins. In the present study, we have modified cobalt based Fischer-Tropsch catalyst and developed a process to minimize methane production, consequently to produce maximum yield of light olefins. Manganese-cobalt oxide supported on H-5A zeolite catalyst was synthesized using modified H-5A zeolite, to increase its surface acid sites. Increased acidity of zeolite plays a major part in the suppression of methane formation during the Fischer-Tropsch reaction. The modified zeolite results in the electronic modification of catalyst surface by creating new active catalytic sites. The results are compared with other supported catalysts along with unmodified zeolite. Appreciable reduction in methane formation is achieved on modified zeolite supported catalyst in comparison with unsupported catalyst.

Select

Hydrogen production via autothermal reforming of ethanol over noble metal catalysts supported on oxides Hongqing Chen;Hao Yu*;Yong Tang;Minqiang Pan;Guangxing Yang;Feng Peng*;Hongjuan Wang;Jian Yang 2009, 18(2): 191-198.  DOI: 摘要 ( 10504 )   PDF   Hydrogen was produced over noble metal (Ir, Ru, Rh, Pd) catalysts supported on various oxides, including -Al2O3, CeO2, ZrO2 and La2O3, via the autothermal reforming reaction of ethanol (ATRE) and oxidative reforming reaction of ethanol (OSRE). The conversion of ethanol and selectivites for hydrogen and byproducts such as methane, ethylene and acetaldehyde were studied. It was found that lanthana alone possessed considerable activity for the ATRE reaction, which could be used as a functional support for ATRE catalysts. It was demonstrated that Ir/La2O3 prevented the formation of methane, and Rh/La2O3 encumbered the production of ethylene and acetaldehyde. ATRE reaction was carried out over La2O3-supported catalysts (Ir/La2O3) with good stability on stream, high conversion, and excellent hydrogen selectivity approaching thermodynamic limit under autothermal condition. Typically, 3.4 H2 molecules can be extracted from a pair of ethanol and water molecules over Ir(5wt%)/La2O3. The results presented in this paper indicate that Ir/La2O3 can be used as a promising catalyst for hydrogen production via ATRE reaction from renewable ethanol.

Select

Carbon nanotubes-Nafion composites as Pt-Ru catalyst support for methanol electro-oxidation in acid media Shengzhou Chen*;Fei Ye;Weiming Lin; 2009, 18(2): 199-204.  DOI: 摘要 ( 7414 )   PDF   Carbon nanotubes-Nafion (CNTs-Nafion) composites were prepared by impregnated CNTs with Nafion in ethanol solution and characterized by FT-IR. Pt-Ru catalysts supported on CNTs-Nafion composites were synthesized by microwave-assisted polyol process. The physical and electrochemical properties of the catalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), CO stripping voltammetry, cyclic voltammetry (CV) and chronoamperometry (CA). The results showed that the Nafion incorporation in CNTs- Nafion composites did not significantly alter the oxygen-containing groups on the CNTs surface. The Pt-Ru catalyst supported on CNTs-Nafion composites with 2 wt% Nafion showed good dispersion and the best CO oxidation and methanol electro-oxidation activities.

Select

Comparison of the water change characteristics between the formation and dissociation of methane hydrate and the freezing and thawing of ice in sand Peng Zhang;Qingbai Wu*;YingmeiWang 2009, 18(2): 205-210.  DOI: 摘要 ( 7212 )   PDF   Hydrate formation and dissociation processes are always accompanied by water migration in porous media, which is similar to the ice. In our study, a novel pF-meter sensor which could detect the changes of water content inside sand was first applied to hydrate formation and dissociation processes, and also can study the water change characteristics in the core scale of a partially saturated silica sand sample and compare the differences of water changes between the processes of formation and dissociation of methane hydrate and freezing and thawing of ice. The experimental results showed that the water changes in the processes of formation and dissociation of methane hydrate were basically similar to that of the freezing and thawing of ice in sand. When methane hydrate or ice was formed, water changes showed the decrease in water content on the whole and the pF values rose following the formation processes. However, there were very obvious differences between the ice thawing and hydrate dissociation.

Select

Catalytic methanol decomposition to carbon monoxide and hydrogen over Pd/CeO2-ZrO2-La2O3 with different Ce/Zr molar ratios Hairong Wang;Yaoqiang Chen;Qiulin Zhang;Qingchao Zhu;Maochu Gong;Ming Zhao* 2009, 18(2): 211-216.  DOI: 摘要 ( 10716 )   PDF   The catalytic behaviors of Pd (1.4 wt%) catalysts supported on CeO2-ZrO2-La2O3 mixed oxides with different Ce/Zr molar ratios were investigated for methanol decomposition. Nitrogen adsorption-desorption (BET), X-ray photoelectron spectroscopy (XPS), H2 temperatureprogrammed reduction (H2-TPR), X-ray diffraction (XRD) and Pd dispersion analysis were used for their characterization. Pd/Ce0.76Zr0.18 La0.06O1.97 catalyst showed the highest BET surface area, best Pd dispersion capability and strongest metal-support interaction. Moreover, XPS showed that there was lattice defect oxygen or mobile oxygen. According to the result of O 1s measurements the lattice defect oxygen or mobile oxygen helped to maintain Pd in a partly oxidized state and increased the activity for methanol decomposition. The Pd/Ce0.76Zr0.18La0.06O1.97 catalyst exhibited the best activity. A 100% conversion of methanol was achieved at around 260 ◦C, which was about 20−40 ◦C lower than other catalysts

Select

Experimental study on geochemical characteristic of methane hydrate formed in porous media Qiang Chen;*;Changling Liu;Yuguang Ye; 2009, 18(2): 217-221.  DOI: 摘要 ( 9753 )   PDF   The natural occurrence of methane hydrates in marine sediments has been intensively studied over the past decades, and geochemical characteristic of hydrate is one of the most attractive research fields. In this paper, we discussed the geochemical anomaly during hydrate formation in porous media. By doing so, we also investigated the temperature influence on hydrate formation under isobaric condition. It turns out that subcooling is an important factor to dominate hydrate formation. Larger subcooling provides more powerful driving force for hydrate formation. During the geochemical anomaly research, six kinds of ions and the total dissolved salt (TDS) were measured before and after the experiment in different porous media. The result is that all kinds of ionic concentration increased after hydrate formation which can be defined as salting out effect mainly affected by gas consumption. But the variation ratio of different ions is not equal. Ca2+ seems to be the most significantly influenced one, and its variation ratio is up to 80%. Finally, we theoretically made a model to calculate the TDS variation, the result is in good accordance with measured one, especially when gas consumption is large.

Select

Thermodynamic analysis of metal dusting on iron in CO-H2-H2O atmosphere Na Lei;Changyu Zhou*;Guiming Hu;Cheng Chen 2009, 18(2): 222-224.  DOI: 摘要 ( 7718 )   PDF   This paper provides a calculation method for carbon activity in CO-H2-H2O atmosphere. The thermodynamic parameters (aC) gas (carbon activity in environment) of different compositions at any temperature can be obtained by △Go T. A theoretical analysis has been conducted into the thermodynamic role of iron and the dependence of possible metal-dusting occurrence on temperature, gas composition and total pressure. In CO-H2-H2O gas mixtures, decreasing the molar fraction of H2O and increasing total pressure expands the temperature region for metal dusting. In CO-H2-H2O gas mixture of different compositions at any temperature and pressure for Fe, depending on relative values of (aC) gas , (aC) Fe3C/Fe and aC = 1, three zones were found to exist.

Select

Hydrogen production from simulated hot coke oven gas by catalytic reforming over Ni/Mg(Al)O catalysts Hongwei Cheng;Baohua Yue;Xueguang Wang&#;Xionggang Lu;Weizhong Ding&#; 2009, 18(2): 225-231.  DOI: 摘要 ( 8666 )   PDF   Hydrogen production by catalytic reforming of simulated hot coke oven gas (HCOG) with toluene as a model tar compound was investigated in a fixed bed reactor over Ni/Mg(Al)O catalysts. The catalysts were prepared by a homogeneous precipitation method using urea hydrolysis and characterized by ICP, BET, XRD, TPR, TEM and TG. XRD showed that the hydrotalcite type precursor after calcination formed (Ni, Mg)Al2O4 spinel and Ni-Mg-O solid solution structure. TPR results suggested that the increase in Ni/Mg molar ratio gave rise to the decrease in the reduction temperature of Ni2+ to Ni0 on Ni/Mg(Al)O catalysts. The reaction results indicated that toluene and CH4 could completely be converted to H2 and CO in the catalytic reforming of the simulated HCOG under atmospheric pressure and the amount of H2 in the reaction effluent gas was about 4 times more than that in original HCOG. The catalysts with lower Ni/Mg molar ratio showed better catalytic activity and resistance to coking, which may become promising catalysts in the catalytic reforming of HCOG.

Select

Effects of the ratio of Fe to Co over Fe-CO/SiO2 bimetallic catalysts on their catalytic performance for Fischer-Tropsch synthesis Xiangdong Ma;Qiwen Sun;Weiyong Ying*;Dingye Fang 2009, 18(2): 232-236.  DOI: 摘要 ( 7611 )   PDF   The Fe-Co/SiO2 bimetallic catalysts with different ratios of Fe to Co were prepared by aqueous incipient wetness impregnation. The catalysts of 10%Fe:0%Co/SiO2, 10%Fe:6%Co/SiO2, 10%Fe:2%Co/SiO2, 10%Fe:10%Co/SiO2, 6%Fe:10%Co/SiO2, 2%Fe:10%Co/SiO2 and 0%Fe: 10%Co/SiO2 by mass were tested in a fixed reactor by the Fischer-Tropsch synthesis. Activity and hydrocarbon distribution were found to be determined by the ratio of iron to cobalt of the catalysts. Higher iron content inhibited the activity, whereas higher cobalt content enhanced the activity of the Fe:Co/SiO2 catalysts. On the other hand, for the catalysts of 10%Fe:6%Co/SiO2, 10%Fe:10%Co/SiO2, 6%Fe:10%Co/SiO2, and 2%Fe:10%Co/SiO2, the total C2–C4 fraction increased (from 10.65% to 26.78%) and C5+ fraction decreased (from 75.75% to 57.63%) at 523 K. Temperature programmed reduction revealed that the addition of cobalt enhanced the reducibility of the Fe:Co/SiO2 catalyst. Metal oxides were present in those catalysts as shown by XRD. The Fe-Co alloy phase was found in the 2%Fe:10%Co/SiO2, 6%Fe:10%Co/SiO2, 10%Fe:10%Co/SiO2, 10%Fe:6%Co/SiO2 catalysts and their crystals were perfect.