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Development of niobium-promoted cobalt catalysts on carbon nanotubes for Fischer-Tropsch synthesis

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Journal of Natural Gas Chemistry 2011年第6期20卷 659-663页

作者： Sardar Ali noor asmawati mohd zabidi Duvvuri Subbarao Department of Chemical Engineering Universiti Teknologi PETRONASBandar Seri Iskandar31750 TronohPerakMalaysia Department of Fundamental and Applied Sciences Universiti Teknologi PETRONASBandar Seri Iskandar31750 TronohPerakMalaysia

Cobalt-based catalysts were prepared by a wet impregnation method on carbon nanotubes （CNTs） support and promoted with *** were characterized by nitrogen adsorption,TEM,XRD,TPR,TPO and *** of niobium increased the dispersion of cobalt but decreased the catalysts ***-Tropsch synthesis （FTS） was carried out in a fixed-bed microreactor at 543 K,1 atm and H2/CO=2 for 5 *** of niobium enhanced the C5＋ hydrocarbons selectivity by 39% and reduced methane selectivity by 59%.These effects were more pronounced for 0.04%Nb/Co/CNTs catalyst,compared with those observed for other niobium compositions.

关键词： CNTs cobalt niobium Fischer-Tropsch synthesis

Synthesis and characterization of niobium-promoted cobalt/iron catalysts supported on carbon nanotubes for the hydrogenation of carbon monoxide

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燃料化学学报 2016年第7期44卷 815-821页

作者： Zahra Gholami noor asmawati mohd zabidi Fatemeh Gholami Mohammadtaghi Vakili Centralized Analytical Laboratory Universiti Teknologi PETRONAS Department of Fundamental and Applied Sciences Universiti Teknologi PETRONAS Department of Mechanical Engineering Faculty of EngineeringUniversity of Malaya School of Industrial Technology Universiti Sains Malaysia

Bimetallic Co /Fe catalysts supported on carbon nanotubes( CNTs) were prepared,and niobium( Nb) was added as promoter to the 70 Co ∶30Fe /CNT catalyst. The physicochemical properties of the catalysts were characterized,and the catalytic performances were analyzed at the same operation conditions( H_2 ∶CO( volume ratio) = 2 ∶1,p = 1 MPa,and t = 260 ℃) in a tubular fixed-bed microreactor system. The addition of Nb to the bimetallic catalyst decreases the average size of the oxide nanoparticles and improves the reducibility of the bimetallic catalyst. Evaluation of the catalyst performance in a Fischer-Tropsch reaction shows that the catalyst results in high selectivity to methane,and the selectivity to C_(5+) increased slightly in the bimetallic catalyst unlike that in the monometallic catalysts. The addition of 1% Nb to the bimetallic catalyst increases CO conversion and selectivity to C_(5+). Meanwhile,a decrease in methane selectivity is observed.

关键词： Fischer-Tropsch synthesis bimetallic catalyst niobium promoter carbon nanotubes

Synthesis and Characterization of Co/Mo Bimetallic Nanocatalysts

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材料科学与工程（中英文A版） 2011年第3X期1卷 390-397页

作者： Sardar Ali noor asmawati mohd zabidi Duvvuri Subbarao Department of Chemical Engineering Universiti Teknologi PETRONAS Bandar Seri lskandar Tronoh 31750 Perak Malaysia Department of Fundamental and Applied Sciences Universiti Teknologi PETRONAS Bandar Seri lskandar Tronoh 31750 Perak Malaysia

Cobalt/Molybdenum bimetallic nanocatalysts were prepared by wet impregnation method on alumina support. Samples 22 adsorption-desorption analyses. Fischer-Tropsch synthesis (FTS) was carried out in a fixed-bed microreactor at 543 K and 1 atm, with H2/CO = 2 v/v and space velocity, SV = 12 L/g·h. The physicochemical properties and the FTS performance of the bimetallic nanocatalysts were analyzed and compared with the monometallic cobalt and molybdenum nanocatalysts. H2-TPR analysis of cobalt nanocatalyst indicated three temperature regions at 490 οC (low temperature), 710 οC (medium temperature) and 820 οC (high temperature). The incorporation of molybdenum into cobalt nanocatalysts increased the percentage of species reduced at low temperature. It also increased the average size of metal nanoparticles and enhanced hydrogen chemisorptions but decreased the degree of reduction of bimetallic nanocatalysts compared to those of the monometallic nanocatalysts. Bimetallic nanocatalysts enhanced the %CO conversion in the FTS. Among the nanocatalysts studied, bimetallic nanocatalyst with the composition of 50Co:50Mo resulted in the highest %CO conversion (42.6%), while the %CO conversion was 28.3% and 24%, respectively for the monometallic cobalt and molybdenum nanocatalysts.

关键词：纳米催化剂双金属金属钴表征合成 H2/CO CO转化率透射电子显微镜

Methanol and DME Co-production from CO2 hydrogenation over hybrid catalysts

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Journal of Chemistry and Chemical Engineering 2009年第12期3卷 37-41,62页

作者： noor asmawati mohd zabidi Muhammad Zahiruddin Ramli Fai Kait Chong Fundamental and Applied Sciences Department Universiti Teknologi PETRONAS Bandar Seri lskandar 31750 Tronoh Perak Da17tl Ridzuan Malaysia

Catalytic hydrogenation of CO2 into methanol and dimethyl ether was carried out over hybrid catalysts consisting of methanol-synthesis catalyst and zeolite. The methanol-synthesis catalyst, Cu/ZnO/Al2O3, was prepared by a co-precipitation method. Then it was physically mixed with HZSM-5 zeolite at weight ratios of 2：1, 1：1 and 1：2. The CO2 hydrogenation reaction was conducted in a fixed-bed microreactor at 250℃ and 40 bar in pre-mixed H2/CO2 feed with H2：CO2 molar ratios of 3：1 and 7：1. Products detected include methanol, dimethyl ether, carbon monoxide and water. Conversion of CO2 and yield of oxygenated products were influenced by the weight ratio of Cu/ZnO/Al2O3：HZSM-5 in the hybrid system and also the feed ratio. The Cu/ZnO/Al2O3： HZSM-5 hybrid at 1：1 resulted in methanol yield of 22.0% and was found to be an efficient hybrid catalyst for the CO2 hydrogenation reaction.

关键词： CO2 methanol dimethyl ether hydrogenation hybrid catalyst

Performance Characterization of Supported Iron Nanocatalysts for Fischer-Tropsch Synthesis

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材料科学与工程（中英文A版） 2011年第1X期1卷 9-15页

作者： Sara Faiz Hanna Tasfy noor asmawati mohd zabidi Duvvuri Subbarao Department of Chemical Engineering Universiti Teknologi PETRONAS Tronoh 31750 Perak Malaysia Department of Fundamental and Applied Sciences Universiti Teknologi PETRONAS Tronoh 31750 Perak Malaysia

This study aimed to develop oxide-supported iron-based nanocatalyst and establish the particle-size dependence of the supported iron nanocatalyst in the Fischer-Tropsch synthesis (FTS) reaction. Iron nanocatalyst was synthesized using impregnation method at 3, 6, 10, and 15 wt % on SiO2 and Al2O3-SiO2 supports. Effects of iron loadings and catalyst supports on the physicochemical properties of supported iron nanoparticles were investigated using N2 physical adsorption, temperature-programmed reduction and electron microscopy. The performance of the supported iron nanocatalysts in the Fischer-Tropsch synthesis (FTS) was studied in a fixed-bed microreactor at atmospheric pressure. The average sizes of iron nanoparticles were 5.8 ± 1.2, 8.6 ± 1.1, 12.6 ± 1.3 and 13 ± 1.2 nm for the 3, 6, 10 and 15 wt% Fe on SiO2, respectively. At lower iron loading (3 and 6 wt %) on SiO2, iron nanoparticles were more uniformly distributed compared to those at higher loadings. Using the Al2O3-SiO2 support, the average sizes of iron nanoparticles for the 3, 6, 10, and 15 wt% Fe were 6.2 ± 1.8, 10 ± 2, 14.5 ± 3.3, and 17.8 ± 5.3 nm, respectively. The 3 and 6 wt% Fe/SiO2 resulted in 60% and 54 % CO conversion, respectively at 250 oC, H2/CO = 1.5 v/v and space velocity, SV=3 L/g-Fe/h. The CO conversion decreased to 30% when Fe loading was increased to 15 wt%. The CO conversion trend correlated to the size of the iron nanoparticles. For 6 wt% Fe/SiO2, the average size of iron nanoparticles was 8.6 nm whereas at 15 wt % iron loading, the average size of the iron nanoparticles was 13 nm. As the size of iron nanoparticles increased from 8.6 nm to 13 nm, the C5+ selectivity decreased from 20% to 11% whereas the selectivity for the light hydrocarbons increased from 55 % to 77%.

关键词：铁纳米粒子纳米催化剂费托合成性能表征 CO转化率 SiO2 Al2O3 物理化学性质

Effects of Pressure on the Performance of CNTs-Supported Catalyst in a Fischer-Tropsch Reaction

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材料科学与工程（中英文B版） 2014年第2期4卷 28-33页

作者： noor asmawati mohd zabidi Sardar Ali Duvvuri Subbarao Department of Fundamental and Applied Sciences Universiti Teknologi PETRONAS Bandar Seri Iskandar Tronoh 31750 PerakMalaysia Department of Chemical Engineering Universiti Teknologi PETRONAS Bandar Seri Iskandar Tronoh 31750 Perak Malaysia

Fischer-Tropsch (FT) reaction involves conversion of syngas (a mixture of carbon monoxide and hydrogen) into higher hydrocarbons in the presence of an active catalyst. The syngas can be derived from non-petroleum feedstocks such as coal, biomass and natural gas, thus the FT reaction provides an alternative route for production of clean fuels. The FT process has received growing interest in recent years due to uncertainty in the Middle East, fast depletion of fossil fuel and environmental concern. This paper reports the synthesis, physicochemical properties and catalytic performance of cobalt-based catalyst in the FT reaction. The catalysts comprised metal nanoparticles supported on carbon nanotubes (CNTs) which were synthesized via a wet impregnation method. The catalysts were characterized using transmission electron microscopy (TEM), temperature-programmed reduction/desorption (TPR/TPD) and X-ray photoelectron spectroscopy (XPS). The performance of the cobalt-based catalyts in a FT reaction was evaluated in a fixed bed microreactor equipped with an on-line gas chromatograph for analyses of hydrocarbon products. The catalysts investigated in this work were Co/CNTs, 70Co30Mn/CNTs, 0.06%K/70Co30Fe/CNTs and 0.04%Nb/70Co30Fe/CNTs. TEM analyses revealed that the average sizes of the metal nanoparticles were 4-5 nm. Based on TPD analyses, the dispersion of these nanoparticles on CNTs were greater than 90%. The presence of both Co2+ and Co3+ ions were confirmed by XPS analysis. The 0.04%Nb/70Co30Fe/CNTs catalyst performed better than other catalysts in the FT reaction where it resulted in CO conversion of 35% and 16% C5+ selectivity at pressure of 1 bar, 220 °C and H2: CO of 2:1. Using the same catalyst, the CO conversion and C5+ selectivity increased to 60% and 57%, respectively when the pressure was increased to 20 bar.

关键词：负载型催化剂反应性能碳纳米管压力升高合成气金属纳米颗粒 X射线光电子能谱钴基催化剂